x86/xen: resume timer irqs early

[linux/fpc-iii.git] / drivers / staging / octeon-usb / cvmx-usb.c

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/**
 * @file
 *
 * "cvmx-usb.c" defines a set of low level USB functions to help
 * developers create Octeon USB drivers for various operating
 * systems. These functions provide a generic API to the Octeon
 * USB blocks, hiding the internal hardware specific
 * operations.
 */
#include <linux/delay.h>
#include <asm/octeon/cvmx.h>
#include <asm/octeon/octeon.h>
#include <asm/octeon/cvmx-sysinfo.h>
#include "cvmx-usbnx-defs.h"
#include "cvmx-usbcx-defs.h"
#include "cvmx-usb.h"
#include <asm/octeon/cvmx-helper.h>
#include <asm/octeon/cvmx-helper-board.h>

#define CVMX_PREFETCH0(address) CVMX_PREFETCH(address, 0)
#define CVMX_PREFETCH128(address) CVMX_PREFETCH(address, 128)
// a normal prefetch
#define CVMX_PREFETCH(address, offset) CVMX_PREFETCH_PREF0(address, offset)
// normal prefetches that use the pref instruction
#define CVMX_PREFETCH_PREFX(X, address, offset) asm volatile ("pref %[type], %[off](%[rbase])" : : [rbase] "d" (address), [off] "I" (offset), [type] "n" (X))
#define CVMX_PREFETCH_PREF0(address, offset) CVMX_PREFETCH_PREFX(0, address, offset)
#define CVMX_CLZ(result, input) asm ("clz %[rd],%[rs]" : [rd] "=d" (result) : [rs] "d" (input))

#define MAX_RETRIES             3               /* Maximum number of times to retry failed transactions */
#define MAX_PIPES               32              /* Maximum number of pipes that can be open at once */
#define MAX_TRANSACTIONS        256             /* Maximum number of outstanding transactions across all pipes */
#define MAX_CHANNELS            8               /* Maximum number of hardware channels supported by the USB block */
#define MAX_USB_ADDRESS         127             /* The highest valid USB device address */
#define MAX_USB_ENDPOINT        15              /* The highest valid USB endpoint number */
#define MAX_USB_HUB_PORT        15              /* The highest valid port number on a hub */
#define MAX_TRANSFER_BYTES      ((1<<19)-1)     /* The low level hardware can transfer a maximum of this number of bytes in each transfer. The field is 19 bits wide */
#define MAX_TRANSFER_PACKETS    ((1<<10)-1)     /* The low level hardware can transfer a maximum of this number of packets in each transfer. The field is 10 bits wide */

/*
 * These defines disable the normal read and write csr. This is so I can add
 * extra debug stuff to the usb specific version and I won't use the normal
 * version by mistake
 */
#define cvmx_read_csr use_cvmx_usb_read_csr64_instead_of_cvmx_read_csr
#define cvmx_write_csr use_cvmx_usb_write_csr64_instead_of_cvmx_write_csr

enum cvmx_usb_transaction_flags {
        __CVMX_USB_TRANSACTION_FLAGS_IN_USE = 1<<16,
};

enum {
        USB_CLOCK_TYPE_REF_12,
        USB_CLOCK_TYPE_REF_24,
        USB_CLOCK_TYPE_REF_48,
        USB_CLOCK_TYPE_CRYSTAL_12,
};

/**
 * Logical transactions may take numerous low level
 * transactions, especially when splits are concerned. This
 * enum represents all of the possible stages a transaction can
 * be in. Note that split completes are always even. This is so
 * the NAK handler can backup to the previous low level
 * transaction with a simple clearing of bit 0.
 */
enum cvmx_usb_stage {
        CVMX_USB_STAGE_NON_CONTROL,
        CVMX_USB_STAGE_NON_CONTROL_SPLIT_COMPLETE,
        CVMX_USB_STAGE_SETUP,
        CVMX_USB_STAGE_SETUP_SPLIT_COMPLETE,
        CVMX_USB_STAGE_DATA,
        CVMX_USB_STAGE_DATA_SPLIT_COMPLETE,
        CVMX_USB_STAGE_STATUS,
        CVMX_USB_STAGE_STATUS_SPLIT_COMPLETE,
};

/**
 * struct cvmx_usb_transaction - describes each pending USB transaction
 *                               regardless of type. These are linked together
 *                               to form a list of pending requests for a pipe.
 *
 * @prev:               Transaction before this one in the pipe.
 * @next:               Transaction after this one in the pipe.
 * @type:               Type of transaction, duplicated of the pipe.
 * @flags:              State flags for this transaction.
 * @buffer:             User's physical buffer address to read/write.
 * @buffer_length:      Size of the user's buffer in bytes.
 * @control_header:     For control transactions, physical address of the 8
 *                      byte standard header.
 * @iso_start_frame:    For ISO transactions, the starting frame number.
 * @iso_number_packets: For ISO transactions, the number of packets in the
 *                      request.
 * @iso_packets:        For ISO transactions, the sub packets in the request.
 * @actual_bytes:       Actual bytes transfer for this transaction.
 * @stage:              For control transactions, the current stage.
 * @callback:           User's callback function when complete.
 * @callback_data:      User's data.
 */
struct cvmx_usb_transaction {
        struct cvmx_usb_transaction *prev;
        struct cvmx_usb_transaction *next;
        enum cvmx_usb_transfer type;
        enum cvmx_usb_transaction_flags flags;
        uint64_t buffer;
        int buffer_length;
        uint64_t control_header;
        int iso_start_frame;
        int iso_number_packets;
        struct cvmx_usb_iso_packet *iso_packets;
        int xfersize;
        int pktcnt;
        int retries;
        int actual_bytes;
        enum cvmx_usb_stage stage;
        cvmx_usb_callback_func_t callback;
        void *callback_data;
};

/**
 * struct cvmx_usb_pipe - a pipe represents a virtual connection between Octeon
 *                        and some USB device. It contains a list of pending
 *                        request to the device.
 *
 * @prev:               Pipe before this one in the list
 * @next:               Pipe after this one in the list
 * @head:               The first pending transaction
 * @tail:               The last pending transaction
 * @interval:           For periodic pipes, the interval between packets in
 *                      frames
 * @next_tx_frame:      The next frame this pipe is allowed to transmit on
 * @flags:              State flags for this pipe
 * @device_speed:       Speed of device connected to this pipe
 * @transfer_type:      Type of transaction supported by this pipe
 * @transfer_dir:       IN or OUT. Ignored for Control
 * @multi_count:        Max packet in a row for the device
 * @max_packet:         The device's maximum packet size in bytes
 * @device_addr:        USB device address at other end of pipe
 * @endpoint_num:       USB endpoint number at other end of pipe
 * @hub_device_addr:    Hub address this device is connected to
 * @hub_port:           Hub port this device is connected to
 * @pid_toggle:         This toggles between 0/1 on every packet send to track
 *                      the data pid needed
 * @channel:            Hardware DMA channel for this pipe
 * @split_sc_frame:     The low order bits of the frame number the split
 *                      complete should be sent on
 */
struct cvmx_usb_pipe {
        struct cvmx_usb_pipe *prev;
        struct cvmx_usb_pipe *next;
        struct cvmx_usb_transaction *head;
        struct cvmx_usb_transaction *tail;
        uint64_t interval;
        uint64_t next_tx_frame;
        enum cvmx_usb_pipe_flags flags;
        enum cvmx_usb_speed device_speed;
        enum cvmx_usb_transfer transfer_type;
        enum cvmx_usb_direction transfer_dir;
        int multi_count;
        uint16_t max_packet;
        uint8_t device_addr;
        uint8_t endpoint_num;
        uint8_t hub_device_addr;
        uint8_t hub_port;
        uint8_t pid_toggle;
        uint8_t channel;
        int8_t split_sc_frame;
};

/**
 * struct cvmx_usb_pipe_list
 *
 * @head: Head of the list, or NULL if empty.
 * @tail: Tail if the list, or NULL if empty.
 */
struct cvmx_usb_pipe_list {
        struct cvmx_usb_pipe *head;
        struct cvmx_usb_pipe *tail;
};

struct cvmx_usb_tx_fifo {
        struct {
                int channel;
                int size;
                uint64_t address;
        } entry[MAX_CHANNELS+1];
        int head;
        int tail;
};

/**
 * struct cvmx_usb_internal_state - the state of the USB block
 *
 * init_flags:             Flags passed to initialize.
 * index:                  Which USB block this is for.
 * idle_hardware_channels: Bit set for every idle hardware channel.
 * usbcx_hprt:             Stored port status so we don't need to read a CSR to
 *                         determine splits.
 * pipe_for_channel:       Map channels to pipes.
 * free_transaction_head:  List of free transactions head.
 * free_transaction_tail:  List of free transactions tail.
 * pipe:                   Storage for pipes.
 * transaction:            Storage for transactions.
 * callback:               User global callbacks.
 * callback_data:          User data for each callback.
 * indent:                 Used by debug output to indent functions.
 * port_status:            Last port status used for change notification.
 * free_pipes:             List of all pipes that are currently closed.
 * idle_pipes:             List of open pipes that have no transactions.
 * active_pipes:           Active pipes indexed by transfer type.
 * frame_number:           Increments every SOF interrupt for time keeping.
 * active_split:           Points to the current active split, or NULL.
 */
struct cvmx_usb_internal_state {
        int init_flags;
        int index;
        int idle_hardware_channels;
        union cvmx_usbcx_hprt usbcx_hprt;
        struct cvmx_usb_pipe *pipe_for_channel[MAX_CHANNELS];
        struct cvmx_usb_transaction *free_transaction_head;
        struct cvmx_usb_transaction *free_transaction_tail;
        struct cvmx_usb_pipe pipe[MAX_PIPES];
        struct cvmx_usb_transaction transaction[MAX_TRANSACTIONS];
        cvmx_usb_callback_func_t callback[__CVMX_USB_CALLBACK_END];
        void *callback_data[__CVMX_USB_CALLBACK_END];
        int indent;
        struct cvmx_usb_port_status port_status;
        struct cvmx_usb_pipe_list free_pipes;
        struct cvmx_usb_pipe_list idle_pipes;
        struct cvmx_usb_pipe_list active_pipes[4];
        uint64_t frame_number;
        struct cvmx_usb_transaction *active_split;
        struct cvmx_usb_tx_fifo periodic;
        struct cvmx_usb_tx_fifo nonperiodic;
};

/* This macro spins on a field waiting for it to reach a value */
#define CVMX_WAIT_FOR_FIELD32(address, type, field, op, value, timeout_usec)\
        ({int result;                                                       \
        do {                                                                \
                uint64_t done = cvmx_get_cycle() + (uint64_t)timeout_usec * \
                        octeon_get_clock_rate() / 1000000;                  \
                type c;                                                     \
                while (1) {                                                 \
                        c.u32 = __cvmx_usb_read_csr32(usb, address);        \
                        if (c.s.field op (value)) {                         \
                                result = 0;                                 \
                                break;                                      \
                        } else if (cvmx_get_cycle() > done) {               \
                                result = -1;                                \
                                break;                                      \
                        } else                                              \
                                cvmx_wait(100);                             \
                }                                                           \
        } while (0);                                                        \
        result; })

/*
 * This macro logically sets a single field in a CSR. It does the sequence
 * read, modify, and write
 */
#define USB_SET_FIELD32(address, type, field, value)            \
        do {                                                    \
                type c;                                         \
                c.u32 = __cvmx_usb_read_csr32(usb, address);    \
                c.s.field = value;                              \
                __cvmx_usb_write_csr32(usb, address, c.u32);    \
        } while (0)

/* Returns the IO address to push/pop stuff data from the FIFOs */
#define USB_FIFO_ADDRESS(channel, usb_index) (CVMX_USBCX_GOTGCTL(usb_index) + ((channel)+1)*0x1000)

static int octeon_usb_get_clock_type(void)
{
        switch (cvmx_sysinfo_get()->board_type) {
        case CVMX_BOARD_TYPE_BBGW_REF:
        case CVMX_BOARD_TYPE_LANAI2_A:
        case CVMX_BOARD_TYPE_LANAI2_U:
        case CVMX_BOARD_TYPE_LANAI2_G:
        case CVMX_BOARD_TYPE_UBNT_E100:
                return USB_CLOCK_TYPE_CRYSTAL_12;
        }
        return USB_CLOCK_TYPE_REF_48;
}

/**
 * Read a USB 32bit CSR. It performs the necessary address swizzle
 * for 32bit CSRs and logs the value in a readable format if
 * debugging is on.
 *
 * @usb:     USB block this access is for
 * @address: 64bit address to read
 *
 * Returns: Result of the read
 */
static inline uint32_t __cvmx_usb_read_csr32(struct cvmx_usb_internal_state *usb,
                                             uint64_t address)
{
        uint32_t result = cvmx_read64_uint32(address ^ 4);
        return result;
}


/**
 * Write a USB 32bit CSR. It performs the necessary address
 * swizzle for 32bit CSRs and logs the value in a readable format
 * if debugging is on.
 *
 * @usb:     USB block this access is for
 * @address: 64bit address to write
 * @value:   Value to write
 */
static inline void __cvmx_usb_write_csr32(struct cvmx_usb_internal_state *usb,
                                          uint64_t address, uint32_t value)
{
        cvmx_write64_uint32(address ^ 4, value);
        cvmx_read64_uint64(CVMX_USBNX_DMA0_INB_CHN0(usb->index));
}


/**
 * Read a USB 64bit CSR. It logs the value in a readable format if
 * debugging is on.
 *
 * @usb:     USB block this access is for
 * @address: 64bit address to read
 *
 * Returns: Result of the read
 */
static inline uint64_t __cvmx_usb_read_csr64(struct cvmx_usb_internal_state *usb,
                                             uint64_t address)
{
        uint64_t result = cvmx_read64_uint64(address);
        return result;
}


/**
 * Write a USB 64bit CSR. It logs the value in a readable format
 * if debugging is on.
 *
 * @usb:     USB block this access is for
 * @address: 64bit address to write
 * @value:   Value to write
 */
static inline void __cvmx_usb_write_csr64(struct cvmx_usb_internal_state *usb,
                                          uint64_t address, uint64_t value)
{
        cvmx_write64_uint64(address, value);
}

/**
 * Return non zero if this pipe connects to a non HIGH speed
 * device through a high speed hub.
 *
 * @usb:    USB block this access is for
 * @pipe:   Pipe to check
 *
 * Returns: Non zero if we need to do split transactions
 */
static inline int __cvmx_usb_pipe_needs_split(struct cvmx_usb_internal_state *usb, struct cvmx_usb_pipe *pipe)
{
        return ((pipe->device_speed != CVMX_USB_SPEED_HIGH) && (usb->usbcx_hprt.s.prtspd == CVMX_USB_SPEED_HIGH));
}


/**
 * Trivial utility function to return the correct PID for a pipe
 *
 * @pipe:   pipe to check
 *
 * Returns: PID for pipe
 */
static inline int __cvmx_usb_get_data_pid(struct cvmx_usb_pipe *pipe)
{
        if (pipe->pid_toggle)
                return 2; /* Data1 */
        else
                return 0; /* Data0 */
}


/**
 * Return the number of USB ports supported by this Octeon
 * chip. If the chip doesn't support USB, or is not supported
 * by this API, a zero will be returned. Most Octeon chips
 * support one usb port, but some support two ports.
 * cvmx_usb_initialize() must be called on independent
 * struct cvmx_usb_state.
 *
 * Returns: Number of port, zero if usb isn't supported
 */
int cvmx_usb_get_num_ports(void)
{
        int arch_ports = 0;

        if (OCTEON_IS_MODEL(OCTEON_CN56XX))
                arch_ports = 1;
        else if (OCTEON_IS_MODEL(OCTEON_CN52XX))
                arch_ports = 2;
        else if (OCTEON_IS_MODEL(OCTEON_CN50XX))
                arch_ports = 1;
        else if (OCTEON_IS_MODEL(OCTEON_CN31XX))
                arch_ports = 1;
        else if (OCTEON_IS_MODEL(OCTEON_CN30XX))
                arch_ports = 1;
        else
                arch_ports = 0;

        return arch_ports;
}


/**
 * Allocate a usb transaction for use
 *
 * @usb:         USB device state populated by
 *               cvmx_usb_initialize().
 *
 * Returns: Transaction or NULL
 */
static inline struct cvmx_usb_transaction *__cvmx_usb_alloc_transaction(struct cvmx_usb_internal_state *usb)
{
        struct cvmx_usb_transaction *t;
        t = usb->free_transaction_head;
        if (t) {
                usb->free_transaction_head = t->next;
                if (!usb->free_transaction_head)
                        usb->free_transaction_tail = NULL;
        }
        if (t) {
                memset(t, 0, sizeof(*t));
                t->flags = __CVMX_USB_TRANSACTION_FLAGS_IN_USE;
        }
        return t;
}


/**
 * Free a usb transaction
 *
 * @usb:         USB device state populated by
 *               cvmx_usb_initialize().
 * @transaction:
 *               Transaction to free
 */
static inline void __cvmx_usb_free_transaction(struct cvmx_usb_internal_state *usb,
                                               struct cvmx_usb_transaction *transaction)
{
        transaction->flags = 0;
        transaction->prev = NULL;
        transaction->next = NULL;
        if (usb->free_transaction_tail)
                usb->free_transaction_tail->next = transaction;
        else
                usb->free_transaction_head = transaction;
        usb->free_transaction_tail = transaction;
}


/**
 * Add a pipe to the tail of a list
 * @list:   List to add pipe to
 * @pipe:   Pipe to add
 */
static inline void __cvmx_usb_append_pipe(struct cvmx_usb_pipe_list *list, struct cvmx_usb_pipe *pipe)
{
        pipe->next = NULL;
        pipe->prev = list->tail;
        if (list->tail)
                list->tail->next = pipe;
        else
                list->head = pipe;
        list->tail = pipe;
}


/**
 * Remove a pipe from a list
 * @list:   List to remove pipe from
 * @pipe:   Pipe to remove
 */
static inline void __cvmx_usb_remove_pipe(struct cvmx_usb_pipe_list *list, struct cvmx_usb_pipe *pipe)
{
        if (list->head == pipe) {
                list->head = pipe->next;
                pipe->next = NULL;
                if (list->head)
                        list->head->prev = NULL;
                else
                        list->tail = NULL;
        } else if (list->tail == pipe) {
                list->tail = pipe->prev;
                list->tail->next = NULL;
                pipe->prev = NULL;
        } else {
                pipe->prev->next = pipe->next;
                pipe->next->prev = pipe->prev;
                pipe->prev = NULL;
                pipe->next = NULL;
        }
}


/**
 * Initialize a USB port for use. This must be called before any
 * other access to the Octeon USB port is made. The port starts
 * off in the disabled state.
 *
 * @state:       Pointer to an empty struct cvmx_usb_state
 *               that will be populated by the initialize call.
 *               This structure is then passed to all other USB
 *               functions.
 * @usb_port_number:
 *               Which Octeon USB port to initialize.
 * @flags:       Flags to control hardware initialization. See
 *               enum cvmx_usb_initialize_flags for the flag
 *               definitions. Some flags are mandatory.
 *
 * Returns: 0 or a negative error code.
 */
int cvmx_usb_initialize(struct cvmx_usb_state *state, int usb_port_number,
                        enum cvmx_usb_initialize_flags flags)
{
        union cvmx_usbnx_clk_ctl usbn_clk_ctl;
        union cvmx_usbnx_usbp_ctl_status usbn_usbp_ctl_status;
        struct cvmx_usb_internal_state *usb = (struct cvmx_usb_internal_state *)state;

        usb->init_flags = flags;

        /* Make sure that state is large enough to store the internal state */
        if (sizeof(*state) < sizeof(*usb))
                return -EINVAL;
        /* At first allow 0-1 for the usb port number */
        if ((usb_port_number < 0) || (usb_port_number > 1))
                return -EINVAL;
        /* For all chips except 52XX there is only one port */
        if (!OCTEON_IS_MODEL(OCTEON_CN52XX) && (usb_port_number > 0))
                return -EINVAL;
        /* Try to determine clock type automatically */
        if ((flags & (CVMX_USB_INITIALIZE_FLAGS_CLOCK_XO_XI |
                      CVMX_USB_INITIALIZE_FLAGS_CLOCK_XO_GND)) == 0) {
                if (octeon_usb_get_clock_type() == USB_CLOCK_TYPE_CRYSTAL_12)
                        flags |= CVMX_USB_INITIALIZE_FLAGS_CLOCK_XO_XI;  /* Only 12 MHZ crystals are supported */
                else
                        flags |= CVMX_USB_INITIALIZE_FLAGS_CLOCK_XO_GND;
        }

        if (flags & CVMX_USB_INITIALIZE_FLAGS_CLOCK_XO_GND) {
                /* Check for auto ref clock frequency */
                if (!(flags & CVMX_USB_INITIALIZE_FLAGS_CLOCK_MHZ_MASK))
                        switch (octeon_usb_get_clock_type()) {
                        case USB_CLOCK_TYPE_REF_12:
                                flags |= CVMX_USB_INITIALIZE_FLAGS_CLOCK_12MHZ;
                                break;
                        case USB_CLOCK_TYPE_REF_24:
                                flags |= CVMX_USB_INITIALIZE_FLAGS_CLOCK_24MHZ;
                                break;
                        case USB_CLOCK_TYPE_REF_48:
                                flags |= CVMX_USB_INITIALIZE_FLAGS_CLOCK_48MHZ;
                                break;
                        default:
                                return -EINVAL;
                                break;
                        }
        }

        memset(usb, 0, sizeof(*usb));
        usb->init_flags = flags;

        /* Initialize the USB state structure */
        {
                int i;
                usb->index = usb_port_number;

                /* Initialize the transaction double linked list */
                usb->free_transaction_head = NULL;
                usb->free_transaction_tail = NULL;
                for (i = 0; i < MAX_TRANSACTIONS; i++)
                        __cvmx_usb_free_transaction(usb, usb->transaction + i);
                for (i = 0; i < MAX_PIPES; i++)
                        __cvmx_usb_append_pipe(&usb->free_pipes, usb->pipe + i);
        }

        /*
         * Power On Reset and PHY Initialization
         *
         * 1. Wait for DCOK to assert (nothing to do)
         *
         * 2a. Write USBN0/1_CLK_CTL[POR] = 1 and
         *     USBN0/1_CLK_CTL[HRST,PRST,HCLK_RST] = 0
         */
        usbn_clk_ctl.u64 = __cvmx_usb_read_csr64(usb, CVMX_USBNX_CLK_CTL(usb->index));
        usbn_clk_ctl.s.por = 1;
        usbn_clk_ctl.s.hrst = 0;
        usbn_clk_ctl.s.prst = 0;
        usbn_clk_ctl.s.hclk_rst = 0;
        usbn_clk_ctl.s.enable = 0;
        /*
         * 2b. Select the USB reference clock/crystal parameters by writing
         *     appropriate values to USBN0/1_CLK_CTL[P_C_SEL, P_RTYPE, P_COM_ON]
         */
        if (usb->init_flags & CVMX_USB_INITIALIZE_FLAGS_CLOCK_XO_GND) {
                /*
                 * The USB port uses 12/24/48MHz 2.5V board clock
                 * source at USB_XO. USB_XI should be tied to GND.
                 * Most Octeon evaluation boards require this setting
                 */
                if (OCTEON_IS_MODEL(OCTEON_CN3XXX)) {
                        usbn_clk_ctl.cn31xx.p_rclk  = 1; /* From CN31XX,CN30XX manual */
                        usbn_clk_ctl.cn31xx.p_xenbn = 0;
                } else if (OCTEON_IS_MODEL(OCTEON_CN56XX) || OCTEON_IS_MODEL(OCTEON_CN50XX))
                        usbn_clk_ctl.cn56xx.p_rtype = 2; /* From CN56XX,CN50XX manual */
                else
                        usbn_clk_ctl.cn52xx.p_rtype = 1; /* From CN52XX manual */

                switch (flags & CVMX_USB_INITIALIZE_FLAGS_CLOCK_MHZ_MASK) {
                case CVMX_USB_INITIALIZE_FLAGS_CLOCK_12MHZ:
                        usbn_clk_ctl.s.p_c_sel = 0;
                        break;
                case CVMX_USB_INITIALIZE_FLAGS_CLOCK_24MHZ:
                        usbn_clk_ctl.s.p_c_sel = 1;
                        break;
                case CVMX_USB_INITIALIZE_FLAGS_CLOCK_48MHZ:
                        usbn_clk_ctl.s.p_c_sel = 2;
                        break;
                }
        } else {
                /*
                 * The USB port uses a 12MHz crystal as clock source
                 * at USB_XO and USB_XI
                 */
                if (OCTEON_IS_MODEL(OCTEON_CN3XXX)) {
                        usbn_clk_ctl.cn31xx.p_rclk  = 1; /* From CN31XX,CN30XX manual */
                        usbn_clk_ctl.cn31xx.p_xenbn = 1;
                } else if (OCTEON_IS_MODEL(OCTEON_CN56XX) || OCTEON_IS_MODEL(OCTEON_CN50XX))
                        usbn_clk_ctl.cn56xx.p_rtype = 0; /* From CN56XX,CN50XX manual */
                else
                        usbn_clk_ctl.cn52xx.p_rtype = 0; /* From CN52XX manual */

                usbn_clk_ctl.s.p_c_sel = 0;
        }
        /*
         * 2c. Select the HCLK via writing USBN0/1_CLK_CTL[DIVIDE, DIVIDE2] and
         *     setting USBN0/1_CLK_CTL[ENABLE] = 1. Divide the core clock down
         *     such that USB is as close as possible to 125Mhz
         */
        {
                int divisor = (octeon_get_clock_rate()+125000000-1)/125000000;
                if (divisor < 4)  /* Lower than 4 doesn't seem to work properly */
                        divisor = 4;
                usbn_clk_ctl.s.divide = divisor;
                usbn_clk_ctl.s.divide2 = 0;
        }
        __cvmx_usb_write_csr64(usb, CVMX_USBNX_CLK_CTL(usb->index),
                               usbn_clk_ctl.u64);
        /* 2d. Write USBN0/1_CLK_CTL[HCLK_RST] = 1 */
        usbn_clk_ctl.s.hclk_rst = 1;
        __cvmx_usb_write_csr64(usb, CVMX_USBNX_CLK_CTL(usb->index),
                               usbn_clk_ctl.u64);
        /* 2e.  Wait 64 core-clock cycles for HCLK to stabilize */
        cvmx_wait(64);
        /*
         * 3. Program the power-on reset field in the USBN clock-control
         *    register:
         *    USBN_CLK_CTL[POR] = 0
         */
        usbn_clk_ctl.s.por = 0;
        __cvmx_usb_write_csr64(usb, CVMX_USBNX_CLK_CTL(usb->index),
                               usbn_clk_ctl.u64);
        /* 4. Wait 1 ms for PHY clock to start */
        mdelay(1);
        /*
         * 5. Program the Reset input from automatic test equipment field in the
         *    USBP control and status register:
         *    USBN_USBP_CTL_STATUS[ATE_RESET] = 1
         */
        usbn_usbp_ctl_status.u64 = __cvmx_usb_read_csr64(usb, CVMX_USBNX_USBP_CTL_STATUS(usb->index));
        usbn_usbp_ctl_status.s.ate_reset = 1;
        __cvmx_usb_write_csr64(usb, CVMX_USBNX_USBP_CTL_STATUS(usb->index),
                               usbn_usbp_ctl_status.u64);
        /* 6. Wait 10 cycles */
        cvmx_wait(10);
        /*
         * 7. Clear ATE_RESET field in the USBN clock-control register:
         *    USBN_USBP_CTL_STATUS[ATE_RESET] = 0
         */
        usbn_usbp_ctl_status.s.ate_reset = 0;
        __cvmx_usb_write_csr64(usb, CVMX_USBNX_USBP_CTL_STATUS(usb->index),
                               usbn_usbp_ctl_status.u64);
        /*
         * 8. Program the PHY reset field in the USBN clock-control register:
         *    USBN_CLK_CTL[PRST] = 1
         */
        usbn_clk_ctl.s.prst = 1;
        __cvmx_usb_write_csr64(usb, CVMX_USBNX_CLK_CTL(usb->index),
                               usbn_clk_ctl.u64);
        /*
         * 9. Program the USBP control and status register to select host or
         *    device mode. USBN_USBP_CTL_STATUS[HST_MODE] = 0 for host, = 1 for
         *    device
         */
        usbn_usbp_ctl_status.s.hst_mode = 0;
        __cvmx_usb_write_csr64(usb, CVMX_USBNX_USBP_CTL_STATUS(usb->index),
                               usbn_usbp_ctl_status.u64);
        /* 10. Wait 1 us */
        udelay(1);
        /*
         * 11. Program the hreset_n field in the USBN clock-control register:
         *     USBN_CLK_CTL[HRST] = 1
         */
        usbn_clk_ctl.s.hrst = 1;
        __cvmx_usb_write_csr64(usb, CVMX_USBNX_CLK_CTL(usb->index),
                               usbn_clk_ctl.u64);
        /* 12. Proceed to USB core initialization */
        usbn_clk_ctl.s.enable = 1;
        __cvmx_usb_write_csr64(usb, CVMX_USBNX_CLK_CTL(usb->index),
                               usbn_clk_ctl.u64);
        udelay(1);

        /*
         * USB Core Initialization
         *
         * 1. Read USBC_GHWCFG1, USBC_GHWCFG2, USBC_GHWCFG3, USBC_GHWCFG4 to
         *    determine USB core configuration parameters.
         *
         *    Nothing needed
         *
         * 2. Program the following fields in the global AHB configuration
         *    register (USBC_GAHBCFG)
         *    DMA mode, USBC_GAHBCFG[DMAEn]: 1 = DMA mode, 0 = slave mode
         *    Burst length, USBC_GAHBCFG[HBSTLEN] = 0
         *    Nonperiodic TxFIFO empty level (slave mode only),
         *    USBC_GAHBCFG[NPTXFEMPLVL]
         *    Periodic TxFIFO empty level (slave mode only),
         *    USBC_GAHBCFG[PTXFEMPLVL]
         *    Global interrupt mask, USBC_GAHBCFG[GLBLINTRMSK] = 1
         */
        {
                union cvmx_usbcx_gahbcfg usbcx_gahbcfg;
                /* Due to an errata, CN31XX doesn't support DMA */
                if (OCTEON_IS_MODEL(OCTEON_CN31XX))
                        usb->init_flags |= CVMX_USB_INITIALIZE_FLAGS_NO_DMA;
                usbcx_gahbcfg.u32 = 0;
                usbcx_gahbcfg.s.dmaen = !(usb->init_flags & CVMX_USB_INITIALIZE_FLAGS_NO_DMA);
                if (usb->init_flags & CVMX_USB_INITIALIZE_FLAGS_NO_DMA)
                        usb->idle_hardware_channels = 0x1;  /* Only use one channel with non DMA */
                else if (OCTEON_IS_MODEL(OCTEON_CN5XXX))
                        usb->idle_hardware_channels = 0xf7; /* CN5XXX have an errata with channel 3 */
                else
                        usb->idle_hardware_channels = 0xff;
                usbcx_gahbcfg.s.hbstlen = 0;
                usbcx_gahbcfg.s.nptxfemplvl = 1;
                usbcx_gahbcfg.s.ptxfemplvl = 1;
                usbcx_gahbcfg.s.glblintrmsk = 1;
                __cvmx_usb_write_csr32(usb, CVMX_USBCX_GAHBCFG(usb->index),
                                       usbcx_gahbcfg.u32);
        }
        /*
         * 3. Program the following fields in USBC_GUSBCFG register.
         *    HS/FS timeout calibration, USBC_GUSBCFG[TOUTCAL] = 0
         *    ULPI DDR select, USBC_GUSBCFG[DDRSEL] = 0
         *    USB turnaround time, USBC_GUSBCFG[USBTRDTIM] = 0x5
         *    PHY low-power clock select, USBC_GUSBCFG[PHYLPWRCLKSEL] = 0
         */
        {
                union cvmx_usbcx_gusbcfg usbcx_gusbcfg;
                usbcx_gusbcfg.u32 = __cvmx_usb_read_csr32(usb, CVMX_USBCX_GUSBCFG(usb->index));
                usbcx_gusbcfg.s.toutcal = 0;
                usbcx_gusbcfg.s.ddrsel = 0;
                usbcx_gusbcfg.s.usbtrdtim = 0x5;
                usbcx_gusbcfg.s.phylpwrclksel = 0;
                __cvmx_usb_write_csr32(usb, CVMX_USBCX_GUSBCFG(usb->index),
                                       usbcx_gusbcfg.u32);
        }
        /*
         * 4. The software must unmask the following bits in the USBC_GINTMSK
         *    register.
         *    OTG interrupt mask, USBC_GINTMSK[OTGINTMSK] = 1
         *    Mode mismatch interrupt mask, USBC_GINTMSK[MODEMISMSK] = 1
         */
        {
                union cvmx_usbcx_gintmsk usbcx_gintmsk;
                int channel;

                usbcx_gintmsk.u32 = __cvmx_usb_read_csr32(usb, CVMX_USBCX_GINTMSK(usb->index));
                usbcx_gintmsk.s.otgintmsk = 1;
                usbcx_gintmsk.s.modemismsk = 1;
                usbcx_gintmsk.s.hchintmsk = 1;
                usbcx_gintmsk.s.sofmsk = 0;
                /* We need RX FIFO interrupts if we don't have DMA */
                if (usb->init_flags & CVMX_USB_INITIALIZE_FLAGS_NO_DMA)
                        usbcx_gintmsk.s.rxflvlmsk = 1;
                __cvmx_usb_write_csr32(usb, CVMX_USBCX_GINTMSK(usb->index),
                                       usbcx_gintmsk.u32);

                /* Disable all channel interrupts. We'll enable them per channel later */
                for (channel = 0; channel < 8; channel++)
                        __cvmx_usb_write_csr32(usb, CVMX_USBCX_HCINTMSKX(channel, usb->index), 0);
        }

        {
                /*
                 * Host Port Initialization
                 *
                 * 1. Program the host-port interrupt-mask field to unmask,
                 *    USBC_GINTMSK[PRTINT] = 1
                 */
                USB_SET_FIELD32(CVMX_USBCX_GINTMSK(usb->index), union cvmx_usbcx_gintmsk,
                                prtintmsk, 1);
                USB_SET_FIELD32(CVMX_USBCX_GINTMSK(usb->index), union cvmx_usbcx_gintmsk,
                                disconnintmsk, 1);
                /*
                 * 2. Program the USBC_HCFG register to select full-speed host
                 *    or high-speed host.
                 */
                {
                        union cvmx_usbcx_hcfg usbcx_hcfg;
                        usbcx_hcfg.u32 = __cvmx_usb_read_csr32(usb, CVMX_USBCX_HCFG(usb->index));
                        usbcx_hcfg.s.fslssupp = 0;
                        usbcx_hcfg.s.fslspclksel = 0;
                        __cvmx_usb_write_csr32(usb, CVMX_USBCX_HCFG(usb->index), usbcx_hcfg.u32);
                }
                /*
                 * 3. Program the port power bit to drive VBUS on the USB,
                 *    USBC_HPRT[PRTPWR] = 1
                 */
                USB_SET_FIELD32(CVMX_USBCX_HPRT(usb->index), union cvmx_usbcx_hprt, prtpwr, 1);

                /*
                 * Steps 4-15 from the manual are done later in the port enable
                 */
        }

        return 0;
}


/**
 * Shutdown a USB port after a call to cvmx_usb_initialize().
 * The port should be disabled with all pipes closed when this
 * function is called.
 *
 * @state: USB device state populated by
 *         cvmx_usb_initialize().
 *
 * Returns: 0 or a negative error code.
 */
int cvmx_usb_shutdown(struct cvmx_usb_state *state)
{
        union cvmx_usbnx_clk_ctl usbn_clk_ctl;
        struct cvmx_usb_internal_state *usb = (struct cvmx_usb_internal_state *)state;

        /* Make sure all pipes are closed */
        if (usb->idle_pipes.head ||
                usb->active_pipes[CVMX_USB_TRANSFER_ISOCHRONOUS].head ||
                usb->active_pipes[CVMX_USB_TRANSFER_INTERRUPT].head ||
                usb->active_pipes[CVMX_USB_TRANSFER_CONTROL].head ||
                usb->active_pipes[CVMX_USB_TRANSFER_BULK].head)
                return -EBUSY;

        /* Disable the clocks and put them in power on reset */
        usbn_clk_ctl.u64 = __cvmx_usb_read_csr64(usb, CVMX_USBNX_CLK_CTL(usb->index));
        usbn_clk_ctl.s.enable = 1;
        usbn_clk_ctl.s.por = 1;
        usbn_clk_ctl.s.hclk_rst = 1;
        usbn_clk_ctl.s.prst = 0;
        usbn_clk_ctl.s.hrst = 0;
        __cvmx_usb_write_csr64(usb, CVMX_USBNX_CLK_CTL(usb->index),
                               usbn_clk_ctl.u64);
        return 0;
}


/**
 * Enable a USB port. After this call succeeds, the USB port is
 * online and servicing requests.
 *
 * @state: USB device state populated by
 *         cvmx_usb_initialize().
 *
 * Returns: 0 or a negative error code.
 */
int cvmx_usb_enable(struct cvmx_usb_state *state)
{
        union cvmx_usbcx_ghwcfg3 usbcx_ghwcfg3;
        struct cvmx_usb_internal_state *usb = (struct cvmx_usb_internal_state *)state;

        usb->usbcx_hprt.u32 = __cvmx_usb_read_csr32(usb, CVMX_USBCX_HPRT(usb->index));

        /*
         * If the port is already enabled the just return. We don't need to do
         * anything
         */
        if (usb->usbcx_hprt.s.prtena)
                return 0;

        /* If there is nothing plugged into the port then fail immediately */
        if (!usb->usbcx_hprt.s.prtconnsts) {
                return -ETIMEDOUT;
        }

        /* Program the port reset bit to start the reset process */
        USB_SET_FIELD32(CVMX_USBCX_HPRT(usb->index), union cvmx_usbcx_hprt, prtrst, 1);

        /*
         * Wait at least 50ms (high speed), or 10ms (full speed) for the reset
         * process to complete.
         */
        mdelay(50);

        /* Program the port reset bit to 0, USBC_HPRT[PRTRST] = 0 */
        USB_SET_FIELD32(CVMX_USBCX_HPRT(usb->index), union cvmx_usbcx_hprt, prtrst, 0);

        /* Wait for the USBC_HPRT[PRTENA]. */
        if (CVMX_WAIT_FOR_FIELD32(CVMX_USBCX_HPRT(usb->index), union cvmx_usbcx_hprt,
                                  prtena, ==, 1, 100000))
                return -ETIMEDOUT;

        /* Read the port speed field to get the enumerated speed, USBC_HPRT[PRTSPD]. */
        usb->usbcx_hprt.u32 = __cvmx_usb_read_csr32(usb, CVMX_USBCX_HPRT(usb->index));
        usbcx_ghwcfg3.u32 = __cvmx_usb_read_csr32(usb, CVMX_USBCX_GHWCFG3(usb->index));

        /*
         * 13. Program the USBC_GRXFSIZ register to select the size of the
         *     receive FIFO (25%).
         */
        USB_SET_FIELD32(CVMX_USBCX_GRXFSIZ(usb->index), union cvmx_usbcx_grxfsiz,
                        rxfdep, usbcx_ghwcfg3.s.dfifodepth / 4);
        /*
         * 14. Program the USBC_GNPTXFSIZ register to select the size and the
         *     start address of the non- periodic transmit FIFO for nonperiodic
         *     transactions (50%).
         */
        {
                union cvmx_usbcx_gnptxfsiz siz;
                siz.u32 = __cvmx_usb_read_csr32(usb, CVMX_USBCX_GNPTXFSIZ(usb->index));
                siz.s.nptxfdep = usbcx_ghwcfg3.s.dfifodepth / 2;
                siz.s.nptxfstaddr = usbcx_ghwcfg3.s.dfifodepth / 4;
                __cvmx_usb_write_csr32(usb, CVMX_USBCX_GNPTXFSIZ(usb->index), siz.u32);
        }
        /*
         * 15. Program the USBC_HPTXFSIZ register to select the size and start
         *     address of the periodic transmit FIFO for periodic transactions
         *     (25%).
         */
        {
                union cvmx_usbcx_hptxfsiz siz;
                siz.u32 = __cvmx_usb_read_csr32(usb, CVMX_USBCX_HPTXFSIZ(usb->index));
                siz.s.ptxfsize = usbcx_ghwcfg3.s.dfifodepth / 4;
                siz.s.ptxfstaddr = 3 * usbcx_ghwcfg3.s.dfifodepth / 4;
                __cvmx_usb_write_csr32(usb, CVMX_USBCX_HPTXFSIZ(usb->index), siz.u32);
        }
        /* Flush all FIFOs */
        USB_SET_FIELD32(CVMX_USBCX_GRSTCTL(usb->index), union cvmx_usbcx_grstctl, txfnum, 0x10);
        USB_SET_FIELD32(CVMX_USBCX_GRSTCTL(usb->index), union cvmx_usbcx_grstctl, txfflsh, 1);
        CVMX_WAIT_FOR_FIELD32(CVMX_USBCX_GRSTCTL(usb->index), union cvmx_usbcx_grstctl,
                              txfflsh, ==, 0, 100);
        USB_SET_FIELD32(CVMX_USBCX_GRSTCTL(usb->index), union cvmx_usbcx_grstctl, rxfflsh, 1);
        CVMX_WAIT_FOR_FIELD32(CVMX_USBCX_GRSTCTL(usb->index), union cvmx_usbcx_grstctl,
                              rxfflsh, ==, 0, 100);

        return 0;
}


/**
 * Disable a USB port. After this call the USB port will not
 * generate data transfers and will not generate events.
 * Transactions in process will fail and call their
 * associated callbacks.
 *
 * @state: USB device state populated by
 *         cvmx_usb_initialize().
 *
 * Returns: 0 or a negative error code.
 */
int cvmx_usb_disable(struct cvmx_usb_state *state)
{
        struct cvmx_usb_internal_state *usb = (struct cvmx_usb_internal_state *)state;

        /* Disable the port */
        USB_SET_FIELD32(CVMX_USBCX_HPRT(usb->index), union cvmx_usbcx_hprt, prtena, 1);
        return 0;
}


/**
 * Get the current state of the USB port. Use this call to
 * determine if the usb port has anything connected, is enabled,
 * or has some sort of error condition. The return value of this
 * call has "changed" bits to signal of the value of some fields
 * have changed between calls. These "changed" fields are based
 * on the last call to cvmx_usb_set_status(). In order to clear
 * them, you must update the status through cvmx_usb_set_status().
 *
 * @state: USB device state populated by
 *         cvmx_usb_initialize().
 *
 * Returns: Port status information
 */
struct cvmx_usb_port_status cvmx_usb_get_status(struct cvmx_usb_state *state)
{
        union cvmx_usbcx_hprt usbc_hprt;
        struct cvmx_usb_port_status result;
        struct cvmx_usb_internal_state *usb = (struct cvmx_usb_internal_state *)state;

        memset(&result, 0, sizeof(result));

        usbc_hprt.u32 = __cvmx_usb_read_csr32(usb, CVMX_USBCX_HPRT(usb->index));
        result.port_enabled = usbc_hprt.s.prtena;
        result.port_over_current = usbc_hprt.s.prtovrcurract;
        result.port_powered = usbc_hprt.s.prtpwr;
        result.port_speed = usbc_hprt.s.prtspd;
        result.connected = usbc_hprt.s.prtconnsts;
        result.connect_change = (result.connected != usb->port_status.connected);

        return result;
}


/**
 * Set the current state of the USB port. The status is used as
 * a reference for the "changed" bits returned by
 * cvmx_usb_get_status(). Other than serving as a reference, the
 * status passed to this function is not used. No fields can be
 * changed through this call.
 *
 * @state:       USB device state populated by
 *               cvmx_usb_initialize().
 * @port_status:
 *               Port status to set, most like returned by cvmx_usb_get_status()
 */
void cvmx_usb_set_status(struct cvmx_usb_state *state, struct cvmx_usb_port_status port_status)
{
        struct cvmx_usb_internal_state *usb = (struct cvmx_usb_internal_state *)state;
        usb->port_status = port_status;
        return;
}


/**
 * Convert a USB transaction into a handle
 *
 * @usb:         USB device state populated by
 *               cvmx_usb_initialize().
 * @transaction:
 *               Transaction to get handle for
 *
 * Returns: Handle
 */
static inline int __cvmx_usb_get_submit_handle(struct cvmx_usb_internal_state *usb,
                                               struct cvmx_usb_transaction *transaction)
{
        return ((unsigned long)transaction - (unsigned long)usb->transaction) /
                        sizeof(*transaction);
}


/**
 * Convert a USB pipe into a handle
 *
 * @usb:         USB device state populated by
 *               cvmx_usb_initialize().
 * @pipe:        Pipe to get handle for
 *
 * Returns: Handle
 */
static inline int __cvmx_usb_get_pipe_handle(struct cvmx_usb_internal_state *usb,
                                             struct cvmx_usb_pipe *pipe)
{
        return ((unsigned long)pipe - (unsigned long)usb->pipe) / sizeof(*pipe);
}


/**
 * Open a virtual pipe between the host and a USB device. A pipe
 * must be opened before data can be transferred between a device
 * and Octeon.
 *
 * @state:           USB device state populated by
 *                   cvmx_usb_initialize().
 * @flags:           Optional pipe flags defined in
 *                   enum cvmx_usb_pipe_flags.
 * @device_addr:
 *                   USB device address to open the pipe to
 *                   (0-127).
 * @endpoint_num:
 *                   USB endpoint number to open the pipe to
 *                   (0-15).
 * @device_speed:
 *                   The speed of the device the pipe is going
 *                   to. This must match the device's speed,
 *                   which may be different than the port speed.
 * @max_packet:      The maximum packet length the device can
 *                   transmit/receive (low speed=0-8, full
 *                   speed=0-1023, high speed=0-1024). This value
 *                   comes from the standard endpoint descriptor
 *                   field wMaxPacketSize bits <10:0>.
 * @transfer_type:
 *                   The type of transfer this pipe is for.
 * @transfer_dir:
 *                   The direction the pipe is in. This is not
 *                   used for control pipes.
 * @interval:        For ISOCHRONOUS and INTERRUPT transfers,
 *                   this is how often the transfer is scheduled
 *                   for. All other transfers should specify
 *                   zero. The units are in frames (8000/sec at
 *                   high speed, 1000/sec for full speed).
 * @multi_count:
 *                   For high speed devices, this is the maximum
 *                   allowed number of packet per microframe.
 *                   Specify zero for non high speed devices. This
 *                   value comes from the standard endpoint descriptor
 *                   field wMaxPacketSize bits <12:11>.
 * @hub_device_addr:
 *                   Hub device address this device is connected
 *                   to. Devices connected directly to Octeon
 *                   use zero. This is only used when the device
 *                   is full/low speed behind a high speed hub.
 *                   The address will be of the high speed hub,
 *                   not and full speed hubs after it.
 * @hub_port:        Which port on the hub the device is
 *                   connected. Use zero for devices connected
 *                   directly to Octeon. Like hub_device_addr,
 *                   this is only used for full/low speed
 *                   devices behind a high speed hub.
 *
 * Returns: A non negative value is a pipe handle. Negative
 *          values are error codes.
 */
int cvmx_usb_open_pipe(struct cvmx_usb_state *state, enum cvmx_usb_pipe_flags flags,
                       int device_addr, int endpoint_num,
                       enum cvmx_usb_speed device_speed, int max_packet,
                       enum cvmx_usb_transfer transfer_type,
                       enum cvmx_usb_direction transfer_dir, int interval,
                       int multi_count, int hub_device_addr, int hub_port)
{
        struct cvmx_usb_pipe *pipe;
        struct cvmx_usb_internal_state *usb = (struct cvmx_usb_internal_state *)state;

        if (unlikely((device_addr < 0) || (device_addr > MAX_USB_ADDRESS)))
                return -EINVAL;
        if (unlikely((endpoint_num < 0) || (endpoint_num > MAX_USB_ENDPOINT)))
                return -EINVAL;
        if (unlikely(device_speed > CVMX_USB_SPEED_LOW))
                return -EINVAL;
        if (unlikely((max_packet <= 0) || (max_packet > 1024)))
                return -EINVAL;
        if (unlikely(transfer_type > CVMX_USB_TRANSFER_INTERRUPT))
                return -EINVAL;
        if (unlikely((transfer_dir != CVMX_USB_DIRECTION_OUT) &&
                (transfer_dir != CVMX_USB_DIRECTION_IN)))
                return -EINVAL;
        if (unlikely(interval < 0))
                return -EINVAL;
        if (unlikely((transfer_type == CVMX_USB_TRANSFER_CONTROL) && interval))
                return -EINVAL;
        if (unlikely(multi_count < 0))
                return -EINVAL;
        if (unlikely((device_speed != CVMX_USB_SPEED_HIGH) &&
                (multi_count != 0)))
                return -EINVAL;
        if (unlikely((hub_device_addr < 0) || (hub_device_addr > MAX_USB_ADDRESS)))
                return -EINVAL;
        if (unlikely((hub_port < 0) || (hub_port > MAX_USB_HUB_PORT)))
                return -EINVAL;

        /* Find a free pipe */
        pipe = usb->free_pipes.head;
        if (!pipe)
                return -ENOMEM;
        __cvmx_usb_remove_pipe(&usb->free_pipes, pipe);
        pipe->flags = flags | __CVMX_USB_PIPE_FLAGS_OPEN;
        if ((device_speed == CVMX_USB_SPEED_HIGH) &&
                (transfer_dir == CVMX_USB_DIRECTION_OUT) &&
                (transfer_type == CVMX_USB_TRANSFER_BULK))
                pipe->flags |= __CVMX_USB_PIPE_FLAGS_NEED_PING;
        pipe->device_addr = device_addr;
        pipe->endpoint_num = endpoint_num;
        pipe->device_speed = device_speed;
        pipe->max_packet = max_packet;
        pipe->transfer_type = transfer_type;
        pipe->transfer_dir = transfer_dir;
        /*
         * All pipes use interval to rate limit NAK processing. Force an
         * interval if one wasn't supplied
         */
        if (!interval)
                interval = 1;
        if (__cvmx_usb_pipe_needs_split(usb, pipe)) {
                pipe->interval = interval*8;
                /* Force start splits to be schedule on uFrame 0 */
                pipe->next_tx_frame = ((usb->frame_number+7)&~7) + pipe->interval;
        } else {
                pipe->interval = interval;
                pipe->next_tx_frame = usb->frame_number + pipe->interval;
        }
        pipe->multi_count = multi_count;
        pipe->hub_device_addr = hub_device_addr;
        pipe->hub_port = hub_port;
        pipe->pid_toggle = 0;
        pipe->split_sc_frame = -1;
        __cvmx_usb_append_pipe(&usb->idle_pipes, pipe);

        /*
         * We don't need to tell the hardware about this pipe yet since
         * it doesn't have any submitted requests
         */

        return __cvmx_usb_get_pipe_handle(usb, pipe);
}


/**
 * Poll the RX FIFOs and remove data as needed. This function is only used
 * in non DMA mode. It is very important that this function be called quickly
 * enough to prevent FIFO overflow.
 *
 * @usb:        USB device state populated by
 *              cvmx_usb_initialize().
 */
static void __cvmx_usb_poll_rx_fifo(struct cvmx_usb_internal_state *usb)
{
        union cvmx_usbcx_grxstsph rx_status;
        int channel;
        int bytes;
        uint64_t address;
        uint32_t *ptr;

        rx_status.u32 = __cvmx_usb_read_csr32(usb, CVMX_USBCX_GRXSTSPH(usb->index));
        /* Only read data if IN data is there */
        if (rx_status.s.pktsts != 2)
                return;
        /* Check if no data is available */
        if (!rx_status.s.bcnt)
                return;

        channel = rx_status.s.chnum;
        bytes = rx_status.s.bcnt;
        if (!bytes)
                return;

        /* Get where the DMA engine would have written this data */
        address = __cvmx_usb_read_csr64(usb, CVMX_USBNX_DMA0_INB_CHN0(usb->index) + channel*8);
        ptr = cvmx_phys_to_ptr(address);
        __cvmx_usb_write_csr64(usb, CVMX_USBNX_DMA0_INB_CHN0(usb->index) + channel*8, address + bytes);

        /* Loop writing the FIFO data for this packet into memory */
        while (bytes > 0) {
                *ptr++ = __cvmx_usb_read_csr32(usb, USB_FIFO_ADDRESS(channel, usb->index));
                bytes -= 4;
        }
        CVMX_SYNCW;

        return;
}


/**
 * Fill the TX hardware fifo with data out of the software
 * fifos
 *
 * @usb:            USB device state populated by
 *                  cvmx_usb_initialize().
 * @fifo:           Software fifo to use
 * @available:      Amount of space in the hardware fifo
 *
 * Returns: Non zero if the hardware fifo was too small and needs
 *          to be serviced again.
 */
static int __cvmx_usb_fill_tx_hw(struct cvmx_usb_internal_state *usb, struct cvmx_usb_tx_fifo *fifo, int available)
{
        /*
         * We're done either when there isn't anymore space or the software FIFO
         * is empty
         */
        while (available && (fifo->head != fifo->tail)) {
                int i = fifo->tail;
                const uint32_t *ptr = cvmx_phys_to_ptr(fifo->entry[i].address);
                uint64_t csr_address = USB_FIFO_ADDRESS(fifo->entry[i].channel, usb->index) ^ 4;
                int words = available;

                /* Limit the amount of data to waht the SW fifo has */
                if (fifo->entry[i].size <= available) {
                        words = fifo->entry[i].size;
                        fifo->tail++;
                        if (fifo->tail > MAX_CHANNELS)
                                fifo->tail = 0;
                }

                /* Update the next locations and counts */
                available -= words;
                fifo->entry[i].address += words * 4;
                fifo->entry[i].size -= words;

                /*
                 * Write the HW fifo data. The read every three writes is due
                 * to an errata on CN3XXX chips
                 */
                while (words > 3) {
                        cvmx_write64_uint32(csr_address, *ptr++);
                        cvmx_write64_uint32(csr_address, *ptr++);
                        cvmx_write64_uint32(csr_address, *ptr++);
                        cvmx_read64_uint64(CVMX_USBNX_DMA0_INB_CHN0(usb->index));
                        words -= 3;
                }
                cvmx_write64_uint32(csr_address, *ptr++);
                if (--words) {
                        cvmx_write64_uint32(csr_address, *ptr++);
                        if (--words)
                                cvmx_write64_uint32(csr_address, *ptr++);
                }
                cvmx_read64_uint64(CVMX_USBNX_DMA0_INB_CHN0(usb->index));
        }
        return fifo->head != fifo->tail;
}


/**
 * Check the hardware FIFOs and fill them as needed
 *
 * @usb:        USB device state populated by
 *              cvmx_usb_initialize().
 */
static void __cvmx_usb_poll_tx_fifo(struct cvmx_usb_internal_state *usb)
{
        if (usb->periodic.head != usb->periodic.tail) {
                union cvmx_usbcx_hptxsts tx_status;
                tx_status.u32 = __cvmx_usb_read_csr32(usb, CVMX_USBCX_HPTXSTS(usb->index));
                if (__cvmx_usb_fill_tx_hw(usb, &usb->periodic, tx_status.s.ptxfspcavail))
                        USB_SET_FIELD32(CVMX_USBCX_GINTMSK(usb->index), union cvmx_usbcx_gintmsk, ptxfempmsk, 1);
                else
                        USB_SET_FIELD32(CVMX_USBCX_GINTMSK(usb->index), union cvmx_usbcx_gintmsk, ptxfempmsk, 0);
        }

        if (usb->nonperiodic.head != usb->nonperiodic.tail) {
                union cvmx_usbcx_gnptxsts tx_status;
                tx_status.u32 = __cvmx_usb_read_csr32(usb, CVMX_USBCX_GNPTXSTS(usb->index));
                if (__cvmx_usb_fill_tx_hw(usb, &usb->nonperiodic, tx_status.s.nptxfspcavail))
                        USB_SET_FIELD32(CVMX_USBCX_GINTMSK(usb->index), union cvmx_usbcx_gintmsk, nptxfempmsk, 1);
                else
                        USB_SET_FIELD32(CVMX_USBCX_GINTMSK(usb->index), union cvmx_usbcx_gintmsk, nptxfempmsk, 0);
        }

        return;
}


/**
 * Fill the TX FIFO with an outgoing packet
 *
 * @usb:          USB device state populated by
 *                cvmx_usb_initialize().
 * @channel:      Channel number to get packet from
 */
static void __cvmx_usb_fill_tx_fifo(struct cvmx_usb_internal_state *usb, int channel)
{
        union cvmx_usbcx_hccharx hcchar;
        union cvmx_usbcx_hcspltx usbc_hcsplt;
        union cvmx_usbcx_hctsizx usbc_hctsiz;
        struct cvmx_usb_tx_fifo *fifo;

        /* We only need to fill data on outbound channels */
        hcchar.u32 = __cvmx_usb_read_csr32(usb, CVMX_USBCX_HCCHARX(channel, usb->index));
        if (hcchar.s.epdir != CVMX_USB_DIRECTION_OUT)
                return;

        /* OUT Splits only have data on the start and not the complete */
        usbc_hcsplt.u32 = __cvmx_usb_read_csr32(usb, CVMX_USBCX_HCSPLTX(channel, usb->index));
        if (usbc_hcsplt.s.spltena && usbc_hcsplt.s.compsplt)
                return;

        /* Find out how many bytes we need to fill and convert it into 32bit words */
        usbc_hctsiz.u32 = __cvmx_usb_read_csr32(usb, CVMX_USBCX_HCTSIZX(channel, usb->index));
        if (!usbc_hctsiz.s.xfersize)
                return;

        if ((hcchar.s.eptype == CVMX_USB_TRANSFER_INTERRUPT) ||
                (hcchar.s.eptype == CVMX_USB_TRANSFER_ISOCHRONOUS))
                fifo = &usb->periodic;
        else
                fifo = &usb->nonperiodic;

        fifo->entry[fifo->head].channel = channel;
        fifo->entry[fifo->head].address = __cvmx_usb_read_csr64(usb, CVMX_USBNX_DMA0_OUTB_CHN0(usb->index) + channel*8);
        fifo->entry[fifo->head].size = (usbc_hctsiz.s.xfersize+3)>>2;
        fifo->head++;
        if (fifo->head > MAX_CHANNELS)
                fifo->head = 0;

        __cvmx_usb_poll_tx_fifo(usb);

        return;
}

/**
 * Perform channel specific setup for Control transactions. All
 * the generic stuff will already have been done in
 * __cvmx_usb_start_channel()
 *
 * @usb:          USB device state populated by
 *                cvmx_usb_initialize().
 * @channel:      Channel to setup
 * @pipe:         Pipe for control transaction
 */
static void __cvmx_usb_start_channel_control(struct cvmx_usb_internal_state *usb,
                                             int channel,
                                             struct cvmx_usb_pipe *pipe)
{
        struct cvmx_usb_transaction *transaction = pipe->head;
        union cvmx_usb_control_header *header =
                cvmx_phys_to_ptr(transaction->control_header);
        int bytes_to_transfer = transaction->buffer_length - transaction->actual_bytes;
        int packets_to_transfer;
        union cvmx_usbcx_hctsizx usbc_hctsiz;

        usbc_hctsiz.u32 = __cvmx_usb_read_csr32(usb, CVMX_USBCX_HCTSIZX(channel, usb->index));

        switch (transaction->stage) {
        case CVMX_USB_STAGE_NON_CONTROL:
        case CVMX_USB_STAGE_NON_CONTROL_SPLIT_COMPLETE:
                cvmx_dprintf("%s: ERROR - Non control stage\n", __FUNCTION__);
                break;
        case CVMX_USB_STAGE_SETUP:
                usbc_hctsiz.s.pid = 3; /* Setup */
                bytes_to_transfer = sizeof(*header);
                /* All Control operations start with a setup going OUT */
                USB_SET_FIELD32(CVMX_USBCX_HCCHARX(channel, usb->index), union cvmx_usbcx_hccharx, epdir, CVMX_USB_DIRECTION_OUT);
                /*
                 * Setup send the control header instead of the buffer data. The
                 * buffer data will be used in the next stage
                 */
                __cvmx_usb_write_csr64(usb, CVMX_USBNX_DMA0_OUTB_CHN0(usb->index) + channel*8, transaction->control_header);
                break;
        case CVMX_USB_STAGE_SETUP_SPLIT_COMPLETE:
                usbc_hctsiz.s.pid = 3; /* Setup */
                bytes_to_transfer = 0;
                /* All Control operations start with a setup going OUT */
                USB_SET_FIELD32(CVMX_USBCX_HCCHARX(channel, usb->index), union cvmx_usbcx_hccharx, epdir, CVMX_USB_DIRECTION_OUT);
                USB_SET_FIELD32(CVMX_USBCX_HCSPLTX(channel, usb->index), union cvmx_usbcx_hcspltx, compsplt, 1);
                break;
        case CVMX_USB_STAGE_DATA:
                usbc_hctsiz.s.pid = __cvmx_usb_get_data_pid(pipe);
                if (__cvmx_usb_pipe_needs_split(usb, pipe)) {
                        if (header->s.request_type & 0x80)
                                bytes_to_transfer = 0;
                        else if (bytes_to_transfer > pipe->max_packet)
                                bytes_to_transfer = pipe->max_packet;
                }
                USB_SET_FIELD32(CVMX_USBCX_HCCHARX(channel, usb->index),
                                union cvmx_usbcx_hccharx, epdir,
                                ((header->s.request_type & 0x80) ?
                                        CVMX_USB_DIRECTION_IN :
                                        CVMX_USB_DIRECTION_OUT));
                break;
        case CVMX_USB_STAGE_DATA_SPLIT_COMPLETE:
                usbc_hctsiz.s.pid = __cvmx_usb_get_data_pid(pipe);
                if (!(header->s.request_type & 0x80))
                        bytes_to_transfer = 0;
                USB_SET_FIELD32(CVMX_USBCX_HCCHARX(channel, usb->index),
                                union cvmx_usbcx_hccharx, epdir,
                                ((header->s.request_type & 0x80) ?
                                        CVMX_USB_DIRECTION_IN :
                                        CVMX_USB_DIRECTION_OUT));
                USB_SET_FIELD32(CVMX_USBCX_HCSPLTX(channel, usb->index), union cvmx_usbcx_hcspltx, compsplt, 1);
                break;
        case CVMX_USB_STAGE_STATUS:
                usbc_hctsiz.s.pid = __cvmx_usb_get_data_pid(pipe);
                bytes_to_transfer = 0;
                USB_SET_FIELD32(CVMX_USBCX_HCCHARX(channel, usb->index), union cvmx_usbcx_hccharx, epdir,
                                ((header->s.request_type & 0x80) ?
                                        CVMX_USB_DIRECTION_OUT :
                                        CVMX_USB_DIRECTION_IN));
                break;
        case CVMX_USB_STAGE_STATUS_SPLIT_COMPLETE:
                usbc_hctsiz.s.pid = __cvmx_usb_get_data_pid(pipe);
                bytes_to_transfer = 0;
                USB_SET_FIELD32(CVMX_USBCX_HCCHARX(channel, usb->index), union cvmx_usbcx_hccharx, epdir,
                                ((header->s.request_type & 0x80) ?
                                        CVMX_USB_DIRECTION_OUT :
                                        CVMX_USB_DIRECTION_IN));
                USB_SET_FIELD32(CVMX_USBCX_HCSPLTX(channel, usb->index), union cvmx_usbcx_hcspltx, compsplt, 1);
                break;
        }

        /*
         * Make sure the transfer never exceeds the byte limit of the hardware.
         * Further bytes will be sent as continued transactions
         */
        if (bytes_to_transfer > MAX_TRANSFER_BYTES) {
                /* Round MAX_TRANSFER_BYTES to a multiple of out packet size */
                bytes_to_transfer = MAX_TRANSFER_BYTES / pipe->max_packet;
                bytes_to_transfer *= pipe->max_packet;
        }

        /*
         * Calculate the number of packets to transfer. If the length is zero
         * we still need to transfer one packet
         */
        packets_to_transfer = (bytes_to_transfer + pipe->max_packet - 1) / pipe->max_packet;
        if (packets_to_transfer == 0)
                packets_to_transfer = 1;
        else if ((packets_to_transfer > 1) && (usb->init_flags & CVMX_USB_INITIALIZE_FLAGS_NO_DMA)) {
                /*
                 * Limit to one packet when not using DMA. Channels must be
                 * restarted between every packet for IN transactions, so there
                 * is no reason to do multiple packets in a row
                 */
                packets_to_transfer = 1;
                bytes_to_transfer = packets_to_transfer * pipe->max_packet;
        } else if (packets_to_transfer > MAX_TRANSFER_PACKETS) {
                /*
                 * Limit the number of packet and data transferred to what the
                 * hardware can handle
                 */
                packets_to_transfer = MAX_TRANSFER_PACKETS;
                bytes_to_transfer = packets_to_transfer * pipe->max_packet;
        }

        usbc_hctsiz.s.xfersize = bytes_to_transfer;
        usbc_hctsiz.s.pktcnt = packets_to_transfer;

        __cvmx_usb_write_csr32(usb, CVMX_USBCX_HCTSIZX(channel, usb->index), usbc_hctsiz.u32);
        return;
}


/**
 * Start a channel to perform the pipe's head transaction
 *
 * @usb:          USB device state populated by
 *                cvmx_usb_initialize().
 * @channel:      Channel to setup
 * @pipe:         Pipe to start
 */
static void __cvmx_usb_start_channel(struct cvmx_usb_internal_state *usb,
                                     int channel,
                                     struct cvmx_usb_pipe *pipe)
{
        struct cvmx_usb_transaction *transaction = pipe->head;

        /* Make sure all writes to the DMA region get flushed */
        CVMX_SYNCW;

        /* Attach the channel to the pipe */
        usb->pipe_for_channel[channel] = pipe;
        pipe->channel = channel;
        pipe->flags |= __CVMX_USB_PIPE_FLAGS_SCHEDULED;

        /* Mark this channel as in use */
        usb->idle_hardware_channels &= ~(1<<channel);

        /* Enable the channel interrupt bits */
        {
                union cvmx_usbcx_hcintx usbc_hcint;
                union cvmx_usbcx_hcintmskx usbc_hcintmsk;
                union cvmx_usbcx_haintmsk usbc_haintmsk;

                /* Clear all channel status bits */
                usbc_hcint.u32 = __cvmx_usb_read_csr32(usb, CVMX_USBCX_HCINTX(channel, usb->index));
                __cvmx_usb_write_csr32(usb, CVMX_USBCX_HCINTX(channel, usb->index), usbc_hcint.u32);

                usbc_hcintmsk.u32 = 0;
                usbc_hcintmsk.s.chhltdmsk = 1;
                if (usb->init_flags & CVMX_USB_INITIALIZE_FLAGS_NO_DMA) {
                        /* Channels need these extra interrupts when we aren't in DMA mode */
                        usbc_hcintmsk.s.datatglerrmsk = 1;
                        usbc_hcintmsk.s.frmovrunmsk = 1;
                        usbc_hcintmsk.s.bblerrmsk = 1;
                        usbc_hcintmsk.s.xacterrmsk = 1;
                        if (__cvmx_usb_pipe_needs_split(usb, pipe)) {
                                /* Splits don't generate xfercompl, so we need ACK and NYET */
                                usbc_hcintmsk.s.nyetmsk = 1;
                                usbc_hcintmsk.s.ackmsk = 1;
                        }
                        usbc_hcintmsk.s.nakmsk = 1;
                        usbc_hcintmsk.s.stallmsk = 1;
                        usbc_hcintmsk.s.xfercomplmsk = 1;
                }
                __cvmx_usb_write_csr32(usb, CVMX_USBCX_HCINTMSKX(channel, usb->index), usbc_hcintmsk.u32);

                /* Enable the channel interrupt to propagate */
                usbc_haintmsk.u32 = __cvmx_usb_read_csr32(usb, CVMX_USBCX_HAINTMSK(usb->index));
                usbc_haintmsk.s.haintmsk |= 1<<channel;
                __cvmx_usb_write_csr32(usb, CVMX_USBCX_HAINTMSK(usb->index), usbc_haintmsk.u32);
        }

        /* Setup the locations the DMA engines use  */
        {
                uint64_t dma_address = transaction->buffer + transaction->actual_bytes;
                if (transaction->type == CVMX_USB_TRANSFER_ISOCHRONOUS)
                        dma_address = transaction->buffer + transaction->iso_packets[0].offset + transaction->actual_bytes;
                __cvmx_usb_write_csr64(usb, CVMX_USBNX_DMA0_OUTB_CHN0(usb->index) + channel*8, dma_address);
                __cvmx_usb_write_csr64(usb, CVMX_USBNX_DMA0_INB_CHN0(usb->index) + channel*8, dma_address);
        }

        /* Setup both the size of the transfer and the SPLIT characteristics */
        {
                union cvmx_usbcx_hcspltx usbc_hcsplt = {.u32 = 0};
                union cvmx_usbcx_hctsizx usbc_hctsiz = {.u32 = 0};
                int packets_to_transfer;
                int bytes_to_transfer = transaction->buffer_length - transaction->actual_bytes;

                /*
                 * ISOCHRONOUS transactions store each individual transfer size
                 * in the packet structure, not the global buffer_length
                 */
                if (transaction->type == CVMX_USB_TRANSFER_ISOCHRONOUS)
                        bytes_to_transfer = transaction->iso_packets[0].length - transaction->actual_bytes;

                /*
                 * We need to do split transactions when we are talking to non
                 * high speed devices that are behind a high speed hub
                 */
                if (__cvmx_usb_pipe_needs_split(usb, pipe)) {
                        /*
                         * On the start split phase (stage is even) record the
                         * frame number we will need to send the split complete.
                         * We only store the lower two bits since the time ahead
                         * can only be two frames
                         */
                        if ((transaction->stage&1) == 0) {
                                if (transaction->type == CVMX_USB_TRANSFER_BULK)
                                        pipe->split_sc_frame = (usb->frame_number + 1) & 0x7f;
                                else
                                        pipe->split_sc_frame = (usb->frame_number + 2) & 0x7f;
                        } else
                                pipe->split_sc_frame = -1;

                        usbc_hcsplt.s.spltena = 1;
                        usbc_hcsplt.s.hubaddr = pipe->hub_device_addr;
                        usbc_hcsplt.s.prtaddr = pipe->hub_port;
                        usbc_hcsplt.s.compsplt = (transaction->stage == CVMX_USB_STAGE_NON_CONTROL_SPLIT_COMPLETE);

                        /*
                         * SPLIT transactions can only ever transmit one data
                         * packet so limit the transfer size to the max packet
                         * size
                         */
                        if (bytes_to_transfer > pipe->max_packet)
                                bytes_to_transfer = pipe->max_packet;

                        /*
                         * ISOCHRONOUS OUT splits are unique in that they limit
                         * data transfers to 188 byte chunks representing the
                         * begin/middle/end of the data or all
                         */
                        if (!usbc_hcsplt.s.compsplt &&
                                (pipe->transfer_dir == CVMX_USB_DIRECTION_OUT) &&
                                (pipe->transfer_type == CVMX_USB_TRANSFER_ISOCHRONOUS)) {
                                /*
                                 * Clear the split complete frame number as
                                 * there isn't going to be a split complete
                                 */
                                pipe->split_sc_frame = -1;
                                /*
                                 * See if we've started this transfer and sent
                                 * data
                                 */
                                if (transaction->actual_bytes == 0) {
                                        /*
                                         * Nothing sent yet, this is either a
                                         * begin or the entire payload
                                         */
                                        if (bytes_to_transfer <= 188)
                                                usbc_hcsplt.s.xactpos = 3; /* Entire payload in one go */
                                        else
                                                usbc_hcsplt.s.xactpos = 2; /* First part of payload */
                                } else {
                                        /*
                                         * Continuing the previous data, we must
                                         * either be in the middle or at the end
                                         */
                                        if (bytes_to_transfer <= 188)
                                                usbc_hcsplt.s.xactpos = 1; /* End of payload */
                                        else
                                                usbc_hcsplt.s.xactpos = 0; /* Middle of payload */
                                }
                                /*
                                 * Again, the transfer size is limited to 188
                                 * bytes
                                 */
                                if (bytes_to_transfer > 188)
                                        bytes_to_transfer = 188;
                        }
                }

                /*
                 * Make sure the transfer never exceeds the byte limit of the
                 * hardware. Further bytes will be sent as continued
                 * transactions
                 */
                if (bytes_to_transfer > MAX_TRANSFER_BYTES) {
                        /*
                         * Round MAX_TRANSFER_BYTES to a multiple of out packet
                         * size
                         */
                        bytes_to_transfer = MAX_TRANSFER_BYTES / pipe->max_packet;
                        bytes_to_transfer *= pipe->max_packet;
                }

                /*
                 * Calculate the number of packets to transfer. If the length is
                 * zero we still need to transfer one packet
                 */
                packets_to_transfer = (bytes_to_transfer + pipe->max_packet - 1) / pipe->max_packet;
                if (packets_to_transfer == 0)
                        packets_to_transfer = 1;
                else if ((packets_to_transfer > 1) && (usb->init_flags & CVMX_USB_INITIALIZE_FLAGS_NO_DMA)) {
                        /*
                         * Limit to one packet when not using DMA. Channels must
                         * be restarted between every packet for IN
                         * transactions, so there is no reason to do multiple
                         * packets in a row
                         */
                        packets_to_transfer = 1;
                        bytes_to_transfer = packets_to_transfer * pipe->max_packet;
                } else if (packets_to_transfer > MAX_TRANSFER_PACKETS) {
                        /*
                         * Limit the number of packet and data transferred to
                         * what the hardware can handle
                         */
                        packets_to_transfer = MAX_TRANSFER_PACKETS;
                        bytes_to_transfer = packets_to_transfer * pipe->max_packet;
                }

                usbc_hctsiz.s.xfersize = bytes_to_transfer;
                usbc_hctsiz.s.pktcnt = packets_to_transfer;

                /* Update the DATA0/DATA1 toggle */
                usbc_hctsiz.s.pid = __cvmx_usb_get_data_pid(pipe);
                /*
                 * High speed pipes may need a hardware ping before they start
                 */
                if (pipe->flags & __CVMX_USB_PIPE_FLAGS_NEED_PING)
                        usbc_hctsiz.s.dopng = 1;

                __cvmx_usb_write_csr32(usb, CVMX_USBCX_HCSPLTX(channel, usb->index), usbc_hcsplt.u32);
                __cvmx_usb_write_csr32(usb, CVMX_USBCX_HCTSIZX(channel, usb->index), usbc_hctsiz.u32);
        }

        /* Setup the Host Channel Characteristics Register */
        {
                union cvmx_usbcx_hccharx usbc_hcchar = {.u32 = 0};

                /*
                 * Set the startframe odd/even properly. This is only used for
                 * periodic
                 */
                usbc_hcchar.s.oddfrm = usb->frame_number&1;

                /*
                 * Set the number of back to back packets allowed by this
                 * endpoint. Split transactions interpret "ec" as the number of
                 * immediate retries of failure. These retries happen too
                 * quickly, so we disable these entirely for splits
                 */
                if (__cvmx_usb_pipe_needs_split(usb, pipe))
                        usbc_hcchar.s.ec = 1;
                else if (pipe->multi_count < 1)
                        usbc_hcchar.s.ec = 1;
                else if (pipe->multi_count > 3)
                        usbc_hcchar.s.ec = 3;
                else
                        usbc_hcchar.s.ec = pipe->multi_count;

                /* Set the rest of the endpoint specific settings */
                usbc_hcchar.s.devaddr = pipe->device_addr;
                usbc_hcchar.s.eptype = transaction->type;
                usbc_hcchar.s.lspddev = (pipe->device_speed == CVMX_USB_SPEED_LOW);
                usbc_hcchar.s.epdir = pipe->transfer_dir;
                usbc_hcchar.s.epnum = pipe->endpoint_num;
                usbc_hcchar.s.mps = pipe->max_packet;
                __cvmx_usb_write_csr32(usb, CVMX_USBCX_HCCHARX(channel, usb->index), usbc_hcchar.u32);
        }

        /* Do transaction type specific fixups as needed */
        switch (transaction->type) {
        case CVMX_USB_TRANSFER_CONTROL:
                __cvmx_usb_start_channel_control(usb, channel, pipe);
                break;
        case CVMX_USB_TRANSFER_BULK:
        case CVMX_USB_TRANSFER_INTERRUPT:
                break;
        case CVMX_USB_TRANSFER_ISOCHRONOUS:
                if (!__cvmx_usb_pipe_needs_split(usb, pipe)) {
                        /*
                         * ISO transactions require different PIDs depending on
                         * direction and how many packets are needed
                         */
                        if (pipe->transfer_dir == CVMX_USB_DIRECTION_OUT) {
                                if (pipe->multi_count < 2) /* Need DATA0 */
                                        USB_SET_FIELD32(CVMX_USBCX_HCTSIZX(channel, usb->index), union cvmx_usbcx_hctsizx, pid, 0);
                                else /* Need MDATA */
                                        USB_SET_FIELD32(CVMX_USBCX_HCTSIZX(channel, usb->index), union cvmx_usbcx_hctsizx, pid, 3);
                        }
                }
                break;
        }
        {
                union cvmx_usbcx_hctsizx usbc_hctsiz = {.u32 = __cvmx_usb_read_csr32(usb, CVMX_USBCX_HCTSIZX(channel, usb->index))};
                transaction->xfersize = usbc_hctsiz.s.xfersize;
                transaction->pktcnt = usbc_hctsiz.s.pktcnt;
        }
        /* Remeber when we start a split transaction */
        if (__cvmx_usb_pipe_needs_split(usb, pipe))
                usb->active_split = transaction;
        USB_SET_FIELD32(CVMX_USBCX_HCCHARX(channel, usb->index), union cvmx_usbcx_hccharx, chena, 1);
        if (usb->init_flags & CVMX_USB_INITIALIZE_FLAGS_NO_DMA)
                __cvmx_usb_fill_tx_fifo(usb, channel);
        return;
}


/**
 * Find a pipe that is ready to be scheduled to hardware.
 * @usb:         USB device state populated by
 *               cvmx_usb_initialize().
 * @list:        Pipe list to search
 * @current_frame:
 *               Frame counter to use as a time reference.
 *
 * Returns: Pipe or NULL if none are ready
 */
static struct cvmx_usb_pipe *__cvmx_usb_find_ready_pipe(struct cvmx_usb_internal_state *usb, struct cvmx_usb_pipe_list *list, uint64_t current_frame)
{
        struct cvmx_usb_pipe *pipe = list->head;
        while (pipe) {
                if (!(pipe->flags & __CVMX_USB_PIPE_FLAGS_SCHEDULED) && pipe->head &&
                        (pipe->next_tx_frame <= current_frame) &&
                        ((pipe->split_sc_frame == -1) || ((((int)current_frame - (int)pipe->split_sc_frame) & 0x7f) < 0x40)) &&
                        (!usb->active_split || (usb->active_split == pipe->head))) {
                        CVMX_PREFETCH(pipe, 128);
                        CVMX_PREFETCH(pipe->head, 0);
                        return pipe;
                }
                pipe = pipe->next;
        }
        return NULL;
}


/**
 * Called whenever a pipe might need to be scheduled to the
 * hardware.
 *
 * @usb:         USB device state populated by
 *               cvmx_usb_initialize().
 * @is_sof:      True if this schedule was called on a SOF interrupt.
 */
static void __cvmx_usb_schedule(struct cvmx_usb_internal_state *usb, int is_sof)
{
        int channel;
        struct cvmx_usb_pipe *pipe;
        int need_sof;
        enum cvmx_usb_transfer ttype;

        if (usb->init_flags & CVMX_USB_INITIALIZE_FLAGS_NO_DMA) {
                /* Without DMA we need to be careful to not schedule something at the end of a frame and cause an overrun */
                union cvmx_usbcx_hfnum hfnum = {.u32 = __cvmx_usb_read_csr32(usb, CVMX_USBCX_HFNUM(usb->index))};
                union cvmx_usbcx_hfir hfir = {.u32 = __cvmx_usb_read_csr32(usb, CVMX_USBCX_HFIR(usb->index))};
                if (hfnum.s.frrem < hfir.s.frint/4)
                        goto done;
        }

        while (usb->idle_hardware_channels) {
                /* Find an idle channel */
                CVMX_CLZ(channel, usb->idle_hardware_channels);
                channel = 31 - channel;
                if (unlikely(channel > 7))
                        break;

                /* Find a pipe needing service */
                pipe = NULL;
                if (is_sof) {
                        /*
                         * Only process periodic pipes on SOF interrupts. This
                         * way we are sure that the periodic data is sent in the
                         * beginning of the frame
                         */
                        pipe = __cvmx_usb_find_ready_pipe(usb, usb->active_pipes + CVMX_USB_TRANSFER_ISOCHRONOUS, usb->frame_number);
                        if (likely(!pipe))
                                pipe = __cvmx_usb_find_ready_pipe(usb, usb->active_pipes + CVMX_USB_TRANSFER_INTERRUPT, usb->frame_number);
                }
                if (likely(!pipe)) {
                        pipe = __cvmx_usb_find_ready_pipe(usb, usb->active_pipes + CVMX_USB_TRANSFER_CONTROL, usb->frame_number);
                        if (likely(!pipe))
                                pipe = __cvmx_usb_find_ready_pipe(usb, usb->active_pipes + CVMX_USB_TRANSFER_BULK, usb->frame_number);
                }
                if (!pipe)
                        break;

                __cvmx_usb_start_channel(usb, channel, pipe);
        }

done:
        /*
         * Only enable SOF interrupts when we have transactions pending in the
         * future that might need to be scheduled
         */
        need_sof = 0;
        for (ttype = CVMX_USB_TRANSFER_CONTROL; ttype <= CVMX_USB_TRANSFER_INTERRUPT; ttype++) {
                pipe = usb->active_pipes[ttype].head;
                while (pipe) {
                        if (pipe->next_tx_frame > usb->frame_number) {
                                need_sof = 1;
                                break;
                        }
                        pipe = pipe->next;
                }
        }
        USB_SET_FIELD32(CVMX_USBCX_GINTMSK(usb->index), union cvmx_usbcx_gintmsk, sofmsk, need_sof);
        return;
}


/**
 * Call a user's callback for a specific reason.
 *
 * @usb:         USB device state populated by
 *               cvmx_usb_initialize().
 * @pipe:        Pipe the callback is for or NULL
 * @transaction:
 *               Transaction the callback is for or NULL
 * @reason:      Reason this callback is being called
 * @complete_code:
 *               Completion code for the transaction, if any
 */
static void __cvmx_usb_perform_callback(struct cvmx_usb_internal_state *usb,
                                        struct cvmx_usb_pipe *pipe,
                                        struct cvmx_usb_transaction *transaction,
                                        enum cvmx_usb_callback reason,
                                        enum cvmx_usb_complete complete_code)
{
        cvmx_usb_callback_func_t callback = usb->callback[reason];
        void *user_data = usb->callback_data[reason];
        int submit_handle = -1;
        int pipe_handle = -1;
        int bytes_transferred = 0;

        if (pipe)
                pipe_handle = __cvmx_usb_get_pipe_handle(usb, pipe);

        if (transaction) {
                submit_handle = __cvmx_usb_get_submit_handle(usb, transaction);
                bytes_transferred = transaction->actual_bytes;
                /* Transactions are allowed to override the default callback */
                if ((reason == CVMX_USB_CALLBACK_TRANSFER_COMPLETE) && transaction->callback) {
                        callback = transaction->callback;
                        user_data = transaction->callback_data;
                }
        }

        if (!callback)
                return;

        callback((struct cvmx_usb_state *)usb, reason, complete_code, pipe_handle, submit_handle,
                 bytes_transferred, user_data);
}


/**
 * Signal the completion of a transaction and free it. The
 * transaction will be removed from the pipe transaction list.
 *
 * @usb:         USB device state populated by
 *               cvmx_usb_initialize().
 * @pipe:        Pipe the transaction is on
 * @transaction:
 *               Transaction that completed
 * @complete_code:
 *               Completion code
 */
static void __cvmx_usb_perform_complete(struct cvmx_usb_internal_state *usb,
                                        struct cvmx_usb_pipe *pipe,
                                        struct cvmx_usb_transaction *transaction,
                                        enum cvmx_usb_complete complete_code)
{
        /* If this was a split then clear our split in progress marker */
        if (usb->active_split == transaction)
                usb->active_split = NULL;

        /*
         * Isochronous transactions need extra processing as they might not be
         * done after a single data transfer
         */
        if (unlikely(transaction->type == CVMX_USB_TRANSFER_ISOCHRONOUS)) {
                /* Update the number of bytes transferred in this ISO packet */
                transaction->iso_packets[0].length = transaction->actual_bytes;
                transaction->iso_packets[0].status = complete_code;

                /*
                 * If there are more ISOs pending and we succeeded, schedule the
                 * next one
                 */
                if ((transaction->iso_number_packets > 1) && (complete_code == CVMX_USB_COMPLETE_SUCCESS)) {
                        transaction->actual_bytes = 0;     /* No bytes transferred for this packet as of yet */
                        transaction->iso_number_packets--; /* One less ISO waiting to transfer */
                        transaction->iso_packets++;        /* Increment to the next location in our packet array */
                        transaction->stage = CVMX_USB_STAGE_NON_CONTROL;
                        goto done;
                }
        }

        /* Remove the transaction from the pipe list */
        if (transaction->next)
                transaction->next->prev = transaction->prev;
        else
                pipe->tail = transaction->prev;
        if (transaction->prev)
                transaction->prev->next = transaction->next;
        else
                pipe->head = transaction->next;
        if (!pipe->head) {
                __cvmx_usb_remove_pipe(usb->active_pipes + pipe->transfer_type, pipe);
                __cvmx_usb_append_pipe(&usb->idle_pipes, pipe);

        }
        __cvmx_usb_perform_callback(usb, pipe, transaction,
                                    CVMX_USB_CALLBACK_TRANSFER_COMPLETE,
                                    complete_code);
        __cvmx_usb_free_transaction(usb, transaction);
done:
        return;
}


/**
 * Submit a usb transaction to a pipe. Called for all types
 * of transactions.
 *
 * @usb:
 * @pipe_handle:
 *                  Which pipe to submit to. Will be validated in this function.
 * @type:           Transaction type
 * @flags:          Flags for the transaction
 * @buffer:         User buffer for the transaction
 * @buffer_length:
 *                  User buffer's length in bytes
 * @control_header:
 *                  For control transactions, the 8 byte standard header
 * @iso_start_frame:
 *                  For ISO transactions, the start frame
 * @iso_number_packets:
 *                  For ISO, the number of packet in the transaction.
 * @iso_packets:
 *                  A description of each ISO packet
 * @callback:       User callback to call when the transaction completes
 * @user_data:      User's data for the callback
 *
 * Returns: Submit handle or negative on failure. Matches the result
 *          in the external API.
 */
static int __cvmx_usb_submit_transaction(struct cvmx_usb_internal_state *usb,
                                         int pipe_handle,
                                         enum cvmx_usb_transfer type,
                                         int flags,
                                         uint64_t buffer,
                                         int buffer_length,
                                         uint64_t control_header,
                                         int iso_start_frame,
                                         int iso_number_packets,
                                         struct cvmx_usb_iso_packet *iso_packets,
                                         cvmx_usb_callback_func_t callback,
                                         void *user_data)
{
        int submit_handle;
        struct cvmx_usb_transaction *transaction;
        struct cvmx_usb_pipe *pipe = usb->pipe + pipe_handle;

        if (unlikely((pipe_handle < 0) || (pipe_handle >= MAX_PIPES)))
                return -EINVAL;
        /* Fail if the pipe isn't open */
        if (unlikely((pipe->flags & __CVMX_USB_PIPE_FLAGS_OPEN) == 0))
                return -EINVAL;
        if (unlikely(pipe->transfer_type != type))
                return -EINVAL;

        transaction = __cvmx_usb_alloc_transaction(usb);
        if (unlikely(!transaction))
                return -ENOMEM;

        transaction->type = type;
        transaction->flags |= flags;
        transaction->buffer = buffer;
        transaction->buffer_length = buffer_length;
        transaction->control_header = control_header;
        transaction->iso_start_frame = iso_start_frame; // FIXME: This is not used, implement it
        transaction->iso_number_packets = iso_number_packets;
        transaction->iso_packets = iso_packets;
        transaction->callback = callback;
        transaction->callback_data = user_data;
        if (transaction->type == CVMX_USB_TRANSFER_CONTROL)
                transaction->stage = CVMX_USB_STAGE_SETUP;
        else
                transaction->stage = CVMX_USB_STAGE_NON_CONTROL;

        transaction->next = NULL;
        if (pipe->tail) {
                transaction->prev = pipe->tail;
                transaction->prev->next = transaction;
        } else {
                if (pipe->next_tx_frame < usb->frame_number)
                        pipe->next_tx_frame = usb->frame_number + pipe->interval -
                                (usb->frame_number - pipe->next_tx_frame) % pipe->interval;
                transaction->prev = NULL;
                pipe->head = transaction;
                __cvmx_usb_remove_pipe(&usb->idle_pipes, pipe);
                __cvmx_usb_append_pipe(usb->active_pipes + pipe->transfer_type, pipe);
        }
        pipe->tail = transaction;

        submit_handle = __cvmx_usb_get_submit_handle(usb, transaction);

        /* We may need to schedule the pipe if this was the head of the pipe */
        if (!transaction->prev)
                __cvmx_usb_schedule(usb, 0);

        return submit_handle;
}


/**
 * Call to submit a USB Bulk transfer to a pipe.
 *
 * @state:          USB device state populated by
 *                  cvmx_usb_initialize().
 * @pipe_handle:
 *                  Handle to the pipe for the transfer.
 * @buffer:         Physical address of the data buffer in
 *                  memory. Note that this is NOT A POINTER, but
 *                  the full 64bit physical address of the
 *                  buffer. This may be zero if buffer_length is
 *                  zero.
 * @buffer_length:
 *                  Length of buffer in bytes.
 * @callback:       Function to call when this transaction
 *                  completes. If the return value of this
 *                  function isn't an error, then this function
 *                  is guaranteed to be called when the
 *                  transaction completes. If this parameter is
 *                  NULL, then the generic callback registered
 *                  through cvmx_usb_register_callback is
 *                  called. If both are NULL, then there is no
 *                  way to know when a transaction completes.
 * @user_data:      User supplied data returned when the
 *                  callback is called. This is only used if
 *                  callback in not NULL.
 *
 * Returns: A submitted transaction handle or negative on
 *          failure. Negative values are error codes.
 */
int cvmx_usb_submit_bulk(struct cvmx_usb_state *state, int pipe_handle,
                         uint64_t buffer, int buffer_length,
                         cvmx_usb_callback_func_t callback,
                         void *user_data)
{
        int submit_handle;
        struct cvmx_usb_internal_state *usb = (struct cvmx_usb_internal_state *)state;

        /* Pipe handle checking is done later in a common place */
        if (unlikely(!buffer))
                return -EINVAL;
        if (unlikely(buffer_length < 0))
                return -EINVAL;

        submit_handle = __cvmx_usb_submit_transaction(usb, pipe_handle,
                                                      CVMX_USB_TRANSFER_BULK,
                                                      0, /* flags */
                                                      buffer,
                                                      buffer_length,
                                                      0, /* control_header */
                                                      0, /* iso_start_frame */
                                                      0, /* iso_number_packets */
                                                      NULL, /* iso_packets */
                                                      callback,
                                                      user_data);
        return submit_handle;
}


/**
 * Call to submit a USB Interrupt transfer to a pipe.
 *
 * @state:          USB device state populated by
 *                  cvmx_usb_initialize().
 * @pipe_handle:
 *                  Handle to the pipe for the transfer.
 * @buffer:         Physical address of the data buffer in
 *                  memory. Note that this is NOT A POINTER, but
 *                  the full 64bit physical address of the
 *                  buffer. This may be zero if buffer_length is
 *                  zero.
 * @buffer_length:
 *                  Length of buffer in bytes.
 * @callback:       Function to call when this transaction
 *                  completes. If the return value of this
 *                  function isn't an error, then this function
 *                  is guaranteed to be called when the
 *                  transaction completes. If this parameter is
 *                  NULL, then the generic callback registered
 *                  through cvmx_usb_register_callback is
 *                  called. If both are NULL, then there is no
 *                  way to know when a transaction completes.
 * @user_data:      User supplied data returned when the
 *                  callback is called. This is only used if
 *                  callback in not NULL.
 *
 * Returns: A submitted transaction handle or negative on
 *          failure. Negative values are error codes.
 */
int cvmx_usb_submit_interrupt(struct cvmx_usb_state *state, int pipe_handle,
                              uint64_t buffer, int buffer_length,
                              cvmx_usb_callback_func_t callback,
                              void *user_data)
{
        int submit_handle;
        struct cvmx_usb_internal_state *usb = (struct cvmx_usb_internal_state *)state;

        /* Pipe handle checking is done later in a common place */
        if (unlikely(!buffer))
                return -EINVAL;
        if (unlikely(buffer_length < 0))
                return -EINVAL;

        submit_handle = __cvmx_usb_submit_transaction(usb, pipe_handle,
                                                      CVMX_USB_TRANSFER_INTERRUPT,
                                                      0, /* flags */
                                                      buffer,
                                                      buffer_length,
                                                      0, /* control_header */
                                                      0, /* iso_start_frame */
                                                      0, /* iso_number_packets */
                                                      NULL, /* iso_packets */
                                                      callback,
                                                      user_data);
        return submit_handle;
}


/**
 * Call to submit a USB Control transfer to a pipe.
 *
 * @state:          USB device state populated by
 *                  cvmx_usb_initialize().
 * @pipe_handle:
 *                  Handle to the pipe for the transfer.
 * @control_header:
 *                  USB 8 byte control header physical address.
 *                  Note that this is NOT A POINTER, but the
 *                  full 64bit physical address of the buffer.
 * @buffer:         Physical address of the data buffer in
 *                  memory. Note that this is NOT A POINTER, but
 *                  the full 64bit physical address of the
 *                  buffer. This may be zero if buffer_length is
 *                  zero.
 * @buffer_length:
 *                  Length of buffer in bytes.
 * @callback:       Function to call when this transaction
 *                  completes. If the return value of this
 *                  function isn't an error, then this function
 *                  is guaranteed to be called when the
 *                  transaction completes. If this parameter is
 *                  NULL, then the generic callback registered
 *                  through cvmx_usb_register_callback is
 *                  called. If both are NULL, then there is no
 *                  way to know when a transaction completes.
 * @user_data:      User supplied data returned when the
 *                  callback is called. This is only used if
 *                  callback in not NULL.
 *
 * Returns: A submitted transaction handle or negative on
 *          failure. Negative values are error codes.
 */
int cvmx_usb_submit_control(struct cvmx_usb_state *state, int pipe_handle,
                            uint64_t control_header,
                            uint64_t buffer, int buffer_length,
                            cvmx_usb_callback_func_t callback,
                            void *user_data)
{
        int submit_handle;
        struct cvmx_usb_internal_state *usb = (struct cvmx_usb_internal_state *)state;
        union cvmx_usb_control_header *header =
                cvmx_phys_to_ptr(control_header);

        /* Pipe handle checking is done later in a common place */
        if (unlikely(!control_header))
                return -EINVAL;
        /* Some drivers send a buffer with a zero length. God only knows why */
        if (unlikely(buffer && (buffer_length < 0)))
                return -EINVAL;
        if (unlikely(!buffer && (buffer_length != 0)))
                return -EINVAL;
        if ((header->s.request_type & 0x80) == 0)
                buffer_length = le16_to_cpu(header->s.length);

        submit_handle = __cvmx_usb_submit_transaction(usb, pipe_handle,
                                                      CVMX_USB_TRANSFER_CONTROL,
                                                      0, /* flags */
                                                      buffer,
                                                      buffer_length,
                                                      control_header,
                                                      0, /* iso_start_frame */
                                                      0, /* iso_number_packets */
                                                      NULL, /* iso_packets */
                                                      callback,
                                                      user_data);
        return submit_handle;
}


/**
 * Call to submit a USB Isochronous transfer to a pipe.
 *
 * @state:          USB device state populated by
 *                  cvmx_usb_initialize().
 * @pipe_handle:
 *                  Handle to the pipe for the transfer.
 * @start_frame:
 *                  Number of frames into the future to schedule
 *                  this transaction.
 * @flags:          Flags to control the transfer. See
 *                  enum cvmx_usb_isochronous_flags for the flag
 *                  definitions.
 * @number_packets:
 *                  Number of sequential packets to transfer.
 *                  "packets" is a pointer to an array of this
 *                  many packet structures.
 * @packets:        Description of each transfer packet as
 *                  defined by struct cvmx_usb_iso_packet. The array
 *                  pointed to here must stay valid until the
 *                  complete callback is called.
 * @buffer:         Physical address of the data buffer in
 *                  memory. Note that this is NOT A POINTER, but
 *                  the full 64bit physical address of the
 *                  buffer. This may be zero if buffer_length is
 *                  zero.
 * @buffer_length:
 *                  Length of buffer in bytes.
 * @callback:       Function to call when this transaction
 *                  completes. If the return value of this
 *                  function isn't an error, then this function
 *                  is guaranteed to be called when the
 *                  transaction completes. If this parameter is
 *                  NULL, then the generic callback registered
 *                  through cvmx_usb_register_callback is
 *                  called. If both are NULL, then there is no
 *                  way to know when a transaction completes.
 * @user_data:      User supplied data returned when the
 *                  callback is called. This is only used if
 *                  callback in not NULL.
 *
 * Returns: A submitted transaction handle or negative on
 *          failure. Negative values are error codes.
 */
int cvmx_usb_submit_isochronous(struct cvmx_usb_state *state, int pipe_handle,
                                int start_frame, int flags,
                                int number_packets,
                                struct cvmx_usb_iso_packet packets[],
                                uint64_t buffer, int buffer_length,
                                cvmx_usb_callback_func_t callback,
                                void *user_data)
{
        int submit_handle;
        struct cvmx_usb_internal_state *usb = (struct cvmx_usb_internal_state *)state;

        /* Pipe handle checking is done later in a common place */
        if (unlikely(start_frame < 0))
                return -EINVAL;
        if (unlikely(flags & ~(CVMX_USB_ISOCHRONOUS_FLAGS_ALLOW_SHORT | CVMX_USB_ISOCHRONOUS_FLAGS_ASAP)))
                return -EINVAL;
        if (unlikely(number_packets < 1))
                return -EINVAL;
        if (unlikely(!packets))
                return -EINVAL;
        if (unlikely(!buffer))
                return -EINVAL;
        if (unlikely(buffer_length < 0))
                return -EINVAL;

        submit_handle = __cvmx_usb_submit_transaction(usb, pipe_handle,
                                                      CVMX_USB_TRANSFER_ISOCHRONOUS,
                                                      flags,
                                                      buffer,
                                                      buffer_length,
                                                      0, /* control_header */
                                                      start_frame,
                                                      number_packets,
                                                      packets,
                                                      callback,
                                                      user_data);
        return submit_handle;
}


/**
 * Cancel one outstanding request in a pipe. Canceling a request
 * can fail if the transaction has already completed before cancel
 * is called. Even after a successful cancel call, it may take
 * a frame or two for the cvmx_usb_poll() function to call the
 * associated callback.
 *
 * @state:       USB device state populated by
 *               cvmx_usb_initialize().
 * @pipe_handle:
 *               Pipe handle to cancel requests in.
 * @submit_handle:
 *               Handle to transaction to cancel, returned by the submit function.
 *
 * Returns: 0 or a negative error code.
 */
int cvmx_usb_cancel(struct cvmx_usb_state *state, int pipe_handle, int submit_handle)
{
        struct cvmx_usb_transaction *transaction;
        struct cvmx_usb_internal_state *usb = (struct cvmx_usb_internal_state *)state;
        struct cvmx_usb_pipe *pipe = usb->pipe + pipe_handle;

        if (unlikely((pipe_handle < 0) || (pipe_handle >= MAX_PIPES)))
                return -EINVAL;
        if (unlikely((submit_handle < 0) || (submit_handle >= MAX_TRANSACTIONS)))
                return -EINVAL;

        /* Fail if the pipe isn't open */
        if (unlikely((pipe->flags & __CVMX_USB_PIPE_FLAGS_OPEN) == 0))
                return -EINVAL;

        transaction = usb->transaction + submit_handle;

        /* Fail if this transaction already completed */
        if (unlikely((transaction->flags & __CVMX_USB_TRANSACTION_FLAGS_IN_USE) == 0))
                return -EINVAL;

        /*
         * If the transaction is the HEAD of the queue and scheduled. We need to
         * treat it special
         */
        if ((pipe->head == transaction) &&
                (pipe->flags & __CVMX_USB_PIPE_FLAGS_SCHEDULED)) {
                union cvmx_usbcx_hccharx usbc_hcchar;

                usb->pipe_for_channel[pipe->channel] = NULL;
                pipe->flags &= ~__CVMX_USB_PIPE_FLAGS_SCHEDULED;

                CVMX_SYNCW;

                usbc_hcchar.u32 = __cvmx_usb_read_csr32(usb, CVMX_USBCX_HCCHARX(pipe->channel, usb->index));
                /* If the channel isn't enabled then the transaction already completed */
                if (usbc_hcchar.s.chena) {
                        usbc_hcchar.s.chdis = 1;
                        __cvmx_usb_write_csr32(usb, CVMX_USBCX_HCCHARX(pipe->channel, usb->index), usbc_hcchar.u32);
                }
        }
        __cvmx_usb_perform_complete(usb, pipe, transaction, CVMX_USB_COMPLETE_CANCEL);
        return 0;
}


/**
 * Cancel all outstanding requests in a pipe. Logically all this
 * does is call cvmx_usb_cancel() in a loop.
 *
 * @state:       USB device state populated by
 *               cvmx_usb_initialize().
 * @pipe_handle:
 *               Pipe handle to cancel requests in.
 *
 * Returns: 0 or a negative error code.
 */
int cvmx_usb_cancel_all(struct cvmx_usb_state *state, int pipe_handle)
{
        struct cvmx_usb_internal_state *usb = (struct cvmx_usb_internal_state *)state;
        struct cvmx_usb_pipe *pipe = usb->pipe + pipe_handle;

        if (unlikely((pipe_handle < 0) || (pipe_handle >= MAX_PIPES)))
                return -EINVAL;

        /* Fail if the pipe isn't open */
        if (unlikely((pipe->flags & __CVMX_USB_PIPE_FLAGS_OPEN) == 0))
                return -EINVAL;

        /* Simply loop through and attempt to cancel each transaction */
        while (pipe->head) {
                int result = cvmx_usb_cancel(state, pipe_handle,
                        __cvmx_usb_get_submit_handle(usb, pipe->head));
                if (unlikely(result != 0))
                        return result;
        }
        return 0;
}


/**
 * Close a pipe created with cvmx_usb_open_pipe().
 *
 * @state:       USB device state populated by
 *               cvmx_usb_initialize().
 * @pipe_handle:
 *               Pipe handle to close.
 *
 * Returns: 0 or a negative error code. EBUSY is returned if the pipe has
 *          outstanding transfers.
 */
int cvmx_usb_close_pipe(struct cvmx_usb_state *state, int pipe_handle)
{
        struct cvmx_usb_internal_state *usb = (struct cvmx_usb_internal_state *)state;
        struct cvmx_usb_pipe *pipe = usb->pipe + pipe_handle;

        if (unlikely((pipe_handle < 0) || (pipe_handle >= MAX_PIPES)))
                return -EINVAL;

        /* Fail if the pipe isn't open */
        if (unlikely((pipe->flags & __CVMX_USB_PIPE_FLAGS_OPEN) == 0))
                return -EINVAL;

        /* Fail if the pipe has pending transactions */
        if (unlikely(pipe->head))
                return -EBUSY;

        pipe->flags = 0;
        __cvmx_usb_remove_pipe(&usb->idle_pipes, pipe);
        __cvmx_usb_append_pipe(&usb->free_pipes, pipe);

        return 0;
}


/**
 * Register a function to be called when various USB events occur.
 *
 * @state:     USB device state populated by
 *             cvmx_usb_initialize().
 * @reason:    Which event to register for.
 * @callback:  Function to call when the event occurs.
 * @user_data: User data parameter to the function.
 *
 * Returns: 0 or a negative error code.
 */
int cvmx_usb_register_callback(struct cvmx_usb_state *state,
                               enum cvmx_usb_callback reason,
                               cvmx_usb_callback_func_t callback,
                               void *user_data)
{
        struct cvmx_usb_internal_state *usb = (struct cvmx_usb_internal_state *)state;

        if (unlikely(reason >= __CVMX_USB_CALLBACK_END))
                return -EINVAL;
        if (unlikely(!callback))
                return -EINVAL;

        usb->callback[reason] = callback;
        usb->callback_data[reason] = user_data;

        return 0;
}


/**
 * Get the current USB protocol level frame number. The frame
 * number is always in the range of 0-0x7ff.
 *
 * @state: USB device state populated by
 *         cvmx_usb_initialize().
 *
 * Returns: USB frame number
 */
int cvmx_usb_get_frame_number(struct cvmx_usb_state *state)
{
        int frame_number;
        struct cvmx_usb_internal_state *usb = (struct cvmx_usb_internal_state *)state;
        union cvmx_usbcx_hfnum usbc_hfnum;

        usbc_hfnum.u32 = __cvmx_usb_read_csr32(usb, CVMX_USBCX_HFNUM(usb->index));
        frame_number = usbc_hfnum.s.frnum;

        return frame_number;
}


/**
 * Poll a channel for status
 *
 * @usb:     USB device
 * @channel: Channel to poll
 *
 * Returns: Zero on success
 */
static int __cvmx_usb_poll_channel(struct cvmx_usb_internal_state *usb, int channel)
{
        union cvmx_usbcx_hcintx usbc_hcint;
        union cvmx_usbcx_hctsizx usbc_hctsiz;
        union cvmx_usbcx_hccharx usbc_hcchar;
        struct cvmx_usb_pipe *pipe;
        struct cvmx_usb_transaction *transaction;
        int bytes_this_transfer;
        int bytes_in_last_packet;
        int packets_processed;
        int buffer_space_left;

        /* Read the interrupt status bits for the channel */
        usbc_hcint.u32 = __cvmx_usb_read_csr32(usb, CVMX_USBCX_HCINTX(channel, usb->index));

        if (usb->init_flags & CVMX_USB_INITIALIZE_FLAGS_NO_DMA) {
                usbc_hcchar.u32 = __cvmx_usb_read_csr32(usb, CVMX_USBCX_HCCHARX(channel, usb->index));

                if (usbc_hcchar.s.chena && usbc_hcchar.s.chdis) {
                        /*
                         * There seems to be a bug in CN31XX which can cause
                         * interrupt IN transfers to get stuck until we do a
                         * write of HCCHARX without changing things
                         */
                        __cvmx_usb_write_csr32(usb, CVMX_USBCX_HCCHARX(channel, usb->index), usbc_hcchar.u32);
                        return 0;
                }

                /*
                 * In non DMA mode the channels don't halt themselves. We need
                 * to manually disable channels that are left running
                 */
                if (!usbc_hcint.s.chhltd) {
                        if (usbc_hcchar.s.chena) {
                                union cvmx_usbcx_hcintmskx hcintmsk;
                                /* Disable all interrupts except CHHLTD */
                                hcintmsk.u32 = 0;
                                hcintmsk.s.chhltdmsk = 1;
                                __cvmx_usb_write_csr32(usb, CVMX_USBCX_HCINTMSKX(channel, usb->index), hcintmsk.u32);
                                usbc_hcchar.s.chdis = 1;
                                __cvmx_usb_write_csr32(usb, CVMX_USBCX_HCCHARX(channel, usb->index), usbc_hcchar.u32);
                                return 0;
                        } else if (usbc_hcint.s.xfercompl) {
                                /* Successful IN/OUT with transfer complete. Channel halt isn't needed */
                        } else {
                                cvmx_dprintf("USB%d: Channel %d interrupt without halt\n", usb->index, channel);
                                return 0;
                        }
                }
        } else {
                /*
                 * There is are no interrupts that we need to process when the
                 * channel is still running
                 */
                if (!usbc_hcint.s.chhltd)
                        return 0;
        }

        /* Disable the channel interrupts now that it is done */
        __cvmx_usb_write_csr32(usb, CVMX_USBCX_HCINTMSKX(channel, usb->index), 0);
        usb->idle_hardware_channels |= (1<<channel);

        /* Make sure this channel is tied to a valid pipe */
        pipe = usb->pipe_for_channel[channel];
        CVMX_PREFETCH(pipe, 0);
        CVMX_PREFETCH(pipe, 128);
        if (!pipe)
                return 0;
        transaction = pipe->head;
        CVMX_PREFETCH0(transaction);

        /*
         * Disconnect this pipe from the HW channel. Later the schedule
         * function will figure out which pipe needs to go
         */
        usb->pipe_for_channel[channel] = NULL;
        pipe->flags &= ~__CVMX_USB_PIPE_FLAGS_SCHEDULED;

        /*
         * Read the channel config info so we can figure out how much data
         * transfered
         */
        usbc_hcchar.u32 = __cvmx_usb_read_csr32(usb, CVMX_USBCX_HCCHARX(channel, usb->index));
        usbc_hctsiz.u32 = __cvmx_usb_read_csr32(usb, CVMX_USBCX_HCTSIZX(channel, usb->index));

        /*
         * Calculating the number of bytes successfully transferred is dependent
         * on the transfer direction
         */
        packets_processed = transaction->pktcnt - usbc_hctsiz.s.pktcnt;
        if (usbc_hcchar.s.epdir) {
                /*
                 * IN transactions are easy. For every byte received the
                 * hardware decrements xfersize. All we need to do is subtract
                 * the current value of xfersize from its starting value and we
                 * know how many bytes were written to the buffer
                 */
                bytes_this_transfer = transaction->xfersize - usbc_hctsiz.s.xfersize;
        } else {
                /*
                 * OUT transaction don't decrement xfersize. Instead pktcnt is
                 * decremented on every successful packet send. The hardware
                 * does this when it receives an ACK, or NYET. If it doesn't
                 * receive one of these responses pktcnt doesn't change
                 */
                bytes_this_transfer = packets_processed * usbc_hcchar.s.mps;
                /*
                 * The last packet may not be a full transfer if we didn't have
                 * enough data
                 */
                if (bytes_this_transfer > transaction->xfersize)
                        bytes_this_transfer = transaction->xfersize;
        }
        /* Figure out how many bytes were in the last packet of the transfer */
        if (packets_processed)
                bytes_in_last_packet = bytes_this_transfer - (packets_processed-1) * usbc_hcchar.s.mps;
        else
                bytes_in_last_packet = bytes_this_transfer;

        /*
         * As a special case, setup transactions output the setup header, not
         * the user's data. For this reason we don't count setup data as bytes
         * transferred
         */
        if ((transaction->stage == CVMX_USB_STAGE_SETUP) ||
                (transaction->stage == CVMX_USB_STAGE_SETUP_SPLIT_COMPLETE))
                bytes_this_transfer = 0;

        /*
         * Add the bytes transferred to the running total. It is important that
         * bytes_this_transfer doesn't count any data that needs to be
         * retransmitted
         */
        transaction->actual_bytes += bytes_this_transfer;
        if (transaction->type == CVMX_USB_TRANSFER_ISOCHRONOUS)
                buffer_space_left = transaction->iso_packets[0].length - transaction->actual_bytes;
        else
                buffer_space_left = transaction->buffer_length - transaction->actual_bytes;

        /*
         * We need to remember the PID toggle state for the next transaction.
         * The hardware already updated it for the next transaction
         */
        pipe->pid_toggle = !(usbc_hctsiz.s.pid == 0);

        /*
         * For high speed bulk out, assume the next transaction will need to do
         * a ping before proceeding. If this isn't true the ACK processing below
         * will clear this flag
         */
        if ((pipe->device_speed == CVMX_USB_SPEED_HIGH) &&
                (pipe->transfer_type == CVMX_USB_TRANSFER_BULK) &&
                (pipe->transfer_dir == CVMX_USB_DIRECTION_OUT))
                pipe->flags |= __CVMX_USB_PIPE_FLAGS_NEED_PING;

        if (usbc_hcint.s.stall) {
                /*
                 * STALL as a response means this transaction cannot be
                 * completed because the device can't process transactions. Tell
                 * the user. Any data that was transferred will be counted on
                 * the actual bytes transferred
                 */
                pipe->pid_toggle = 0;
                __cvmx_usb_perform_complete(usb, pipe, transaction, CVMX_USB_COMPLETE_STALL);
        } else if (usbc_hcint.s.xacterr) {
                /*
                 * We know at least one packet worked if we get a ACK or NAK.
                 * Reset the retry counter
                 */
                if (usbc_hcint.s.nak || usbc_hcint.s.ack)
                        transaction->retries = 0;
                transaction->retries++;
                if (transaction->retries > MAX_RETRIES) {
                        /*
                         * XactErr as a response means the device signaled
                         * something wrong with the transfer. For example, PID
                         * toggle errors cause these
                         */
                        __cvmx_usb_perform_complete(usb, pipe, transaction, CVMX_USB_COMPLETE_XACTERR);
                } else {
                        /*
                         * If this was a split then clear our split in progress
                         * marker
                         */
                        if (usb->active_split == transaction)
                                usb->active_split = NULL;
                        /*
                         * Rewind to the beginning of the transaction by anding
                         * off the split complete bit
                         */
                        transaction->stage &= ~1;
                        pipe->split_sc_frame = -1;
                        pipe->next_tx_frame += pipe->interval;
                        if (pipe->next_tx_frame < usb->frame_number)
                                pipe->next_tx_frame = usb->frame_number + pipe->interval -
                                                      (usb->frame_number - pipe->next_tx_frame) % pipe->interval;
                }
        } else if (usbc_hcint.s.bblerr) {
                /* Babble Error (BblErr) */
                __cvmx_usb_perform_complete(usb, pipe, transaction, CVMX_USB_COMPLETE_BABBLEERR);
        } else if (usbc_hcint.s.datatglerr) {
                /* We'll retry the exact same transaction again */
                transaction->retries++;
        } else if (usbc_hcint.s.nyet) {
                /*
                 * NYET as a response is only allowed in three cases: as a
                 * response to a ping, as a response to a split transaction, and
                 * as a response to a bulk out. The ping case is handled by
                 * hardware, so we only have splits and bulk out
                 */
                if (!__cvmx_usb_pipe_needs_split(usb, pipe)) {
                        transaction->retries = 0;
                        /*
                         * If there is more data to go then we need to try
                         * again. Otherwise this transaction is complete
                         */
                        if ((buffer_space_left == 0) || (bytes_in_last_packet < pipe->max_packet))
                                __cvmx_usb_perform_complete(usb, pipe, transaction, CVMX_USB_COMPLETE_SUCCESS);
                } else {
                        /*
                         * Split transactions retry the split complete 4 times
                         * then rewind to the start split and do the entire
                         * transactions again
                         */
                        transaction->retries++;
                        if ((transaction->retries & 0x3) == 0) {
                                /*
                                 * Rewind to the beginning of the transaction by
                                 * anding off the split complete bit
                                 */
                                transaction->stage &= ~1;
                                pipe->split_sc_frame = -1;
                        }
                }
        } else if (usbc_hcint.s.ack) {
                transaction->retries = 0;
                /*
                 * The ACK bit can only be checked after the other error bits.
                 * This is because a multi packet transfer may succeed in a
                 * number of packets and then get a different response on the
                 * last packet. In this case both ACK and the last response bit
                 * will be set. If none of the other response bits is set, then
                 * the last packet must have been an ACK
                 *
                 * Since we got an ACK, we know we don't need to do a ping on
                 * this pipe
                 */
                pipe->flags &= ~__CVMX_USB_PIPE_FLAGS_NEED_PING;

                switch (transaction->type) {
                case CVMX_USB_TRANSFER_CONTROL:
                        switch (transaction->stage) {
                        case CVMX_USB_STAGE_NON_CONTROL:
                        case CVMX_USB_STAGE_NON_CONTROL_SPLIT_COMPLETE:
                                /* This should be impossible */
                                __cvmx_usb_perform_complete(usb, pipe, transaction, CVMX_USB_COMPLETE_ERROR);
                                break;
                        case CVMX_USB_STAGE_SETUP:
                                pipe->pid_toggle = 1;
                                if (__cvmx_usb_pipe_needs_split(usb, pipe))
                                        transaction->stage = CVMX_USB_STAGE_SETUP_SPLIT_COMPLETE;
                                else {
                                        union cvmx_usb_control_header *header =
                                                cvmx_phys_to_ptr(transaction->control_header);
                                        if (header->s.length)
                                                transaction->stage = CVMX_USB_STAGE_DATA;
                                        else
                                                transaction->stage = CVMX_USB_STAGE_STATUS;
                                }
                                break;
                        case CVMX_USB_STAGE_SETUP_SPLIT_COMPLETE:
                                {
                                        union cvmx_usb_control_header *header =
                                                cvmx_phys_to_ptr(transaction->control_header);
                                        if (header->s.length)
                                                transaction->stage = CVMX_USB_STAGE_DATA;
                                        else
                                                transaction->stage = CVMX_USB_STAGE_STATUS;
                                }
                                break;
                        case CVMX_USB_STAGE_DATA:
                                if (__cvmx_usb_pipe_needs_split(usb, pipe)) {
                                        transaction->stage = CVMX_USB_STAGE_DATA_SPLIT_COMPLETE;
                                        /*
                                         * For setup OUT data that are splits,
                                         * the hardware doesn't appear to count
                                         * transferred data. Here we manually
                                         * update the data transferred
                                         */
                                        if (!usbc_hcchar.s.epdir) {
                                                if (buffer_space_left < pipe->max_packet)
                                                        transaction->actual_bytes += buffer_space_left;
                                                else
                                                        transaction->actual_bytes += pipe->max_packet;
                                        }
                                } else if ((buffer_space_left == 0) || (bytes_in_last_packet < pipe->max_packet)) {
                                        pipe->pid_toggle = 1;
                                        transaction->stage = CVMX_USB_STAGE_STATUS;
                                }
                                break;
                        case CVMX_USB_STAGE_DATA_SPLIT_COMPLETE:
                                if ((buffer_space_left == 0) || (bytes_in_last_packet < pipe->max_packet)) {
                                        pipe->pid_toggle = 1;
                                        transaction->stage = CVMX_USB_STAGE_STATUS;
                                } else {
                                        transaction->stage = CVMX_USB_STAGE_DATA;
                                }
                                break;
                        case CVMX_USB_STAGE_STATUS:
                                if (__cvmx_usb_pipe_needs_split(usb, pipe))
                                        transaction->stage = CVMX_USB_STAGE_STATUS_SPLIT_COMPLETE;
                                else
                                        __cvmx_usb_perform_complete(usb, pipe, transaction, CVMX_USB_COMPLETE_SUCCESS);
                                break;
                        case CVMX_USB_STAGE_STATUS_SPLIT_COMPLETE:
                                __cvmx_usb_perform_complete(usb, pipe, transaction, CVMX_USB_COMPLETE_SUCCESS);
                                break;
                        }
                        break;
                case CVMX_USB_TRANSFER_BULK:
                case CVMX_USB_TRANSFER_INTERRUPT:
                        /*
                         * The only time a bulk transfer isn't complete when it
                         * finishes with an ACK is during a split transaction.
                         * For splits we need to continue the transfer if more
                         * data is needed
                         */
                        if (__cvmx_usb_pipe_needs_split(usb, pipe)) {
                                if (transaction->stage == CVMX_USB_STAGE_NON_CONTROL)
                                        transaction->stage = CVMX_USB_STAGE_NON_CONTROL_SPLIT_COMPLETE;
                                else {
                                        if (buffer_space_left && (bytes_in_last_packet == pipe->max_packet))
                                                transaction->stage = CVMX_USB_STAGE_NON_CONTROL;
                                        else {
                                                if (transaction->type == CVMX_USB_TRANSFER_INTERRUPT)
                                                        pipe->next_tx_frame += pipe->interval;
                                                        __cvmx_usb_perform_complete(usb, pipe, transaction, CVMX_USB_COMPLETE_SUCCESS);
                                        }
                                }
                        } else {
                                if ((pipe->device_speed == CVMX_USB_SPEED_HIGH) &&
                                    (pipe->transfer_type == CVMX_USB_TRANSFER_BULK) &&
                                    (pipe->transfer_dir == CVMX_USB_DIRECTION_OUT) &&
                                    (usbc_hcint.s.nak))
                                        pipe->flags |= __CVMX_USB_PIPE_FLAGS_NEED_PING;
                                if (!buffer_space_left || (bytes_in_last_packet < pipe->max_packet)) {
                                        if (transaction->type == CVMX_USB_TRANSFER_INTERRUPT)
                                                pipe->next_tx_frame += pipe->interval;
                                        __cvmx_usb_perform_complete(usb, pipe, transaction, CVMX_USB_COMPLETE_SUCCESS);
                                }
                        }
                        break;
                case CVMX_USB_TRANSFER_ISOCHRONOUS:
                        if (__cvmx_usb_pipe_needs_split(usb, pipe)) {
                                /*
                                 * ISOCHRONOUS OUT splits don't require a
                                 * complete split stage. Instead they use a
                                 * sequence of begin OUT splits to transfer the
                                 * data 188 bytes at a time. Once the transfer
                                 * is complete, the pipe sleeps until the next
                                 * schedule interval
                                 */
                                if (pipe->transfer_dir == CVMX_USB_DIRECTION_OUT) {
                                        /*
                                         * If no space left or this wasn't a max
                                         * size packet then this transfer is
                                         * complete. Otherwise start it again to
                                         * send the next 188 bytes
                                         */
                                        if (!buffer_space_left || (bytes_this_transfer < 188)) {
                                                pipe->next_tx_frame += pipe->interval;
                                                __cvmx_usb_perform_complete(usb, pipe, transaction, CVMX_USB_COMPLETE_SUCCESS);
                                        }
                                } else {
                                        if (transaction->stage == CVMX_USB_STAGE_NON_CONTROL_SPLIT_COMPLETE) {
                                                /*
                                                 * We are in the incoming data
                                                 * phase. Keep getting data
                                                 * until we run out of space or
                                                 * get a small packet
                                                 */
                                                if ((buffer_space_left == 0) || (bytes_in_last_packet < pipe->max_packet)) {
                                                        pipe->next_tx_frame += pipe->interval;
                                                        __cvmx_usb_perform_complete(usb, pipe, transaction, CVMX_USB_COMPLETE_SUCCESS);
                                                }
                                        } else
                                                transaction->stage = CVMX_USB_STAGE_NON_CONTROL_SPLIT_COMPLETE;
                                }
                        } else {
                                pipe->next_tx_frame += pipe->interval;
                                __cvmx_usb_perform_complete(usb, pipe, transaction, CVMX_USB_COMPLETE_SUCCESS);
                        }
                        break;
                }
        } else if (usbc_hcint.s.nak) {
                /* If this was a split then clear our split in progress marker */
                if (usb->active_split == transaction)
                        usb->active_split = NULL;
                /*
                 * NAK as a response means the device couldn't accept the
                 * transaction, but it should be retried in the future. Rewind
                 * to the beginning of the transaction by anding off the split
                 * complete bit. Retry in the next interval
                 */
                transaction->retries = 0;
                transaction->stage &= ~1;
                pipe->next_tx_frame += pipe->interval;
                if (pipe->next_tx_frame < usb->frame_number)
                        pipe->next_tx_frame = usb->frame_number + pipe->interval -
                                (usb->frame_number - pipe->next_tx_frame) % pipe->interval;
        } else {
                struct cvmx_usb_port_status port;
                port = cvmx_usb_get_status((struct cvmx_usb_state *)usb);
                if (port.port_enabled) {
                        /* We'll retry the exact same transaction again */
                        transaction->retries++;
                } else {
                        /*
                         * We get channel halted interrupts with no result bits
                         * sets when the cable is unplugged
                         */
                        __cvmx_usb_perform_complete(usb, pipe, transaction, CVMX_USB_COMPLETE_ERROR);
                }
        }
        return 0;
}


/**
 * Poll the USB block for status and call all needed callback
 * handlers. This function is meant to be called in the interrupt
 * handler for the USB controller. It can also be called
 * periodically in a loop for non-interrupt based operation.
 *
 * @state:      USB device state populated by
 *              cvmx_usb_initialize().
 *
 * Returns: 0 or a negative error code.
 */
int cvmx_usb_poll(struct cvmx_usb_state *state)
{
        union cvmx_usbcx_hfnum usbc_hfnum;
        union cvmx_usbcx_gintsts usbc_gintsts;
        struct cvmx_usb_internal_state *usb = (struct cvmx_usb_internal_state *)state;

        CVMX_PREFETCH(usb, 0);
        CVMX_PREFETCH(usb, 1*128);
        CVMX_PREFETCH(usb, 2*128);
        CVMX_PREFETCH(usb, 3*128);
        CVMX_PREFETCH(usb, 4*128);

        /* Update the frame counter */
        usbc_hfnum.u32 = __cvmx_usb_read_csr32(usb, CVMX_USBCX_HFNUM(usb->index));
        if ((usb->frame_number&0x3fff) > usbc_hfnum.s.frnum)
                usb->frame_number += 0x4000;
        usb->frame_number &= ~0x3fffull;
        usb->frame_number |= usbc_hfnum.s.frnum;

        /* Read the pending interrupts */
        usbc_gintsts.u32 = __cvmx_usb_read_csr32(usb, CVMX_USBCX_GINTSTS(usb->index));

        /* Clear the interrupts now that we know about them */
        __cvmx_usb_write_csr32(usb, CVMX_USBCX_GINTSTS(usb->index), usbc_gintsts.u32);

        if (usbc_gintsts.s.rxflvl) {
                /*
                 * RxFIFO Non-Empty (RxFLvl)
                 * Indicates that there is at least one packet pending to be
                 * read from the RxFIFO.
                 *
                 * In DMA mode this is handled by hardware
                 */
                if (usb->init_flags & CVMX_USB_INITIALIZE_FLAGS_NO_DMA)
                        __cvmx_usb_poll_rx_fifo(usb);
        }
        if (usbc_gintsts.s.ptxfemp || usbc_gintsts.s.nptxfemp) {
                /* Fill the Tx FIFOs when not in DMA mode */
                if (usb->init_flags & CVMX_USB_INITIALIZE_FLAGS_NO_DMA)
                        __cvmx_usb_poll_tx_fifo(usb);
        }
        if (usbc_gintsts.s.disconnint || usbc_gintsts.s.prtint) {
                union cvmx_usbcx_hprt usbc_hprt;
                /*
                 * Disconnect Detected Interrupt (DisconnInt)
                 * Asserted when a device disconnect is detected.
                 *
                 * Host Port Interrupt (PrtInt)
                 * The core sets this bit to indicate a change in port status of
                 * one of the O2P USB core ports in Host mode. The application
                 * must read the Host Port Control and Status (HPRT) register to
                 * determine the exact event that caused this interrupt. The
                 * application must clear the appropriate status bit in the Host
                 * Port Control and Status register to clear this bit.
                 *
                 * Call the user's port callback
                 */
                __cvmx_usb_perform_callback(usb, NULL, NULL,
                                            CVMX_USB_CALLBACK_PORT_CHANGED,
                                            CVMX_USB_COMPLETE_SUCCESS);
                /* Clear the port change bits */
                usbc_hprt.u32 = __cvmx_usb_read_csr32(usb, CVMX_USBCX_HPRT(usb->index));
                usbc_hprt.s.prtena = 0;
                __cvmx_usb_write_csr32(usb, CVMX_USBCX_HPRT(usb->index), usbc_hprt.u32);
        }
        if (usbc_gintsts.s.hchint) {
                /*
                 * Host Channels Interrupt (HChInt)
                 * The core sets this bit to indicate that an interrupt is
                 * pending on one of the channels of the core (in Host mode).
                 * The application must read the Host All Channels Interrupt
                 * (HAINT) register to determine the exact number of the channel
                 * on which the interrupt occurred, and then read the
                 * corresponding Host Channel-n Interrupt (HCINTn) register to
                 * determine the exact cause of the interrupt. The application
                 * must clear the appropriate status bit in the HCINTn register
                 * to clear this bit.
                 */
                union cvmx_usbcx_haint usbc_haint;
                usbc_haint.u32 = __cvmx_usb_read_csr32(usb, CVMX_USBCX_HAINT(usb->index));
                while (usbc_haint.u32) {
                        int channel;
                        CVMX_CLZ(channel, usbc_haint.u32);
                        channel = 31 - channel;
                        __cvmx_usb_poll_channel(usb, channel);
                        usbc_haint.u32 ^= 1<<channel;
                }
        }

        __cvmx_usb_schedule(usb, usbc_gintsts.s.sof);

        return 0;
}