On Tue, Nov 06, 2007 at 02:33:53AM -0800, akpm@linux-foundation.org wrote:

[mmotm.git] / drivers / staging / octeon / cvmx-cmd-queue.h

/***********************license start***************
 * Author: Cavium Networks
 *
 * Contact: support@caviumnetworks.com
 * This file is part of the OCTEON SDK
 *
 * Copyright (c) 2003-2008 Cavium Networks
 *
 * This file is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License, Version 2, as
 * published by the Free Software Foundation.
 *
 * This file is distributed in the hope that it will be useful, but
 * AS-IS and WITHOUT ANY WARRANTY; without even the implied warranty
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, TITLE, or
 * NONINFRINGEMENT.  See the GNU General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this file; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 * or visit http://www.gnu.org/licenses/.
 *
 * This file may also be available under a different license from Cavium.
 * Contact Cavium Networks for more information
 ***********************license end**************************************/

/*
 *
 * Support functions for managing command queues used for
 * various hardware blocks.
 *
 * The common command queue infrastructure abstracts out the
 * software necessary for adding to Octeon's chained queue
 * structures. These structures are used for commands to the
 * PKO, ZIP, DFA, RAID, and DMA engine blocks. Although each
 * hardware unit takes commands and CSRs of different types,
 * they all use basic linked command buffers to store the
 * pending request. In general, users of the CVMX API don't
 * call cvmx-cmd-queue functions directly. Instead the hardware
 * unit specific wrapper should be used. The wrappers perform
 * unit specific validation and CSR writes to submit the
 * commands.
 *
 * Even though most software will never directly interact with
 * cvmx-cmd-queue, knowledge of its internal working can help
 * in diagnosing performance problems and help with debugging.
 *
 * Command queue pointers are stored in a global named block
 * called "cvmx_cmd_queues". Except for the PKO queues, each
 * hardware queue is stored in its own cache line to reduce SMP
 * contention on spin locks. The PKO queues are stored such that
 * every 16th queue is next to each other in memory. This scheme
 * allows for queues being in separate cache lines when there
 * are low number of queues per port. With 16 queues per port,
 * the first queue for each port is in the same cache area. The
 * second queues for each port are in another area, etc. This
 * allows software to implement very efficient lockless PKO with
 * 16 queues per port using a minimum of cache lines per core.
 * All queues for a given core will be isolated in the same
 * cache area.
 *
 * In addition to the memory pointer layout, cvmx-cmd-queue
 * provides an optimized fair ll/sc locking mechanism for the
 * queues. The lock uses a "ticket / now serving" model to
 * maintain fair order on contended locks. In addition, it uses
 * predicted locking time to limit cache contention. When a core
 * know it must wait in line for a lock, it spins on the
 * internal cycle counter to completely eliminate any causes of
 * bus traffic.
 *
 */

#ifndef __CVMX_CMD_QUEUE_H__
#define __CVMX_CMD_QUEUE_H__

#include <linux/prefetch.h>

#include "cvmx-fpa.h"
/**
 * By default we disable the max depth support. Most programs
 * don't use it and it slows down the command queue processing
 * significantly.
 */
#ifndef CVMX_CMD_QUEUE_ENABLE_MAX_DEPTH
#define CVMX_CMD_QUEUE_ENABLE_MAX_DEPTH 0
#endif

/**
 * Enumeration representing all hardware blocks that use command
 * queues. Each hardware block has up to 65536 sub identifiers for
 * multiple command queues. Not all chips support all hardware
 * units.
 */
typedef enum {
        CVMX_CMD_QUEUE_PKO_BASE = 0x00000,

#define CVMX_CMD_QUEUE_PKO(queue) \
        ((cvmx_cmd_queue_id_t)(CVMX_CMD_QUEUE_PKO_BASE + (0xffff&(queue))))

        CVMX_CMD_QUEUE_ZIP = 0x10000,
        CVMX_CMD_QUEUE_DFA = 0x20000,
        CVMX_CMD_QUEUE_RAID = 0x30000,
        CVMX_CMD_QUEUE_DMA_BASE = 0x40000,

#define CVMX_CMD_QUEUE_DMA(queue) \
        ((cvmx_cmd_queue_id_t)(CVMX_CMD_QUEUE_DMA_BASE + (0xffff&(queue))))

        CVMX_CMD_QUEUE_END = 0x50000,
} cvmx_cmd_queue_id_t;

/**
 * Command write operations can fail if the comamnd queue needs
 * a new buffer and the associated FPA pool is empty. It can also
 * fail if the number of queued command words reaches the maximum
 * set at initialization.
 */
typedef enum {
        CVMX_CMD_QUEUE_SUCCESS = 0,
        CVMX_CMD_QUEUE_NO_MEMORY = -1,
        CVMX_CMD_QUEUE_FULL = -2,
        CVMX_CMD_QUEUE_INVALID_PARAM = -3,
        CVMX_CMD_QUEUE_ALREADY_SETUP = -4,
} cvmx_cmd_queue_result_t;

typedef struct {
        /* You have lock when this is your ticket */
        uint8_t now_serving;
        uint64_t unused1:24;
        /* Maximum outstanding command words */
        uint32_t max_depth;
        /* FPA pool buffers come from */
        uint64_t fpa_pool:3;
        /* Top of command buffer pointer shifted 7 */
        uint64_t base_ptr_div128:29;
        uint64_t unused2:6;
        /* FPA buffer size in 64bit words minus 1 */
        uint64_t pool_size_m1:13;
        /* Number of comamnds already used in buffer */
        uint64_t index:13;
} __cvmx_cmd_queue_state_t;

/**
 * This structure contains the global state of all comamnd queues.
 * It is stored in a bootmem named block and shared by all
 * applications running on Octeon. Tickets are stored in a differnet
 * cahce line that queue information to reduce the contention on the
 * ll/sc used to get a ticket. If this is not the case, the update
 * of queue state causes the ll/sc to fail quite often.
 */
typedef struct {
        uint64_t ticket[(CVMX_CMD_QUEUE_END >> 16) * 256];
        __cvmx_cmd_queue_state_t state[(CVMX_CMD_QUEUE_END >> 16) * 256];
} __cvmx_cmd_queue_all_state_t;

/**
 * Initialize a command queue for use. The initial FPA buffer is
 * allocated and the hardware unit is configured to point to the
 * new command queue.
 *
 * @queue_id:  Hardware command queue to initialize.
 * @max_depth: Maximum outstanding commands that can be queued.
 * @fpa_pool:  FPA pool the command queues should come from.
 * @pool_size: Size of each buffer in the FPA pool (bytes)
 *
 * Returns CVMX_CMD_QUEUE_SUCCESS or a failure code
 */
cvmx_cmd_queue_result_t cvmx_cmd_queue_initialize(cvmx_cmd_queue_id_t queue_id,
                                                  int max_depth, int fpa_pool,
                                                  int pool_size);

/**
 * Shutdown a queue a free it's command buffers to the FPA. The
 * hardware connected to the queue must be stopped before this
 * function is called.
 *
 * @queue_id: Queue to shutdown
 *
 * Returns CVMX_CMD_QUEUE_SUCCESS or a failure code
 */
cvmx_cmd_queue_result_t cvmx_cmd_queue_shutdown(cvmx_cmd_queue_id_t queue_id);

/**
 * Return the number of command words pending in the queue. This
 * function may be relatively slow for some hardware units.
 *
 * @queue_id: Hardware command queue to query
 *
 * Returns Number of outstanding commands
 */
int cvmx_cmd_queue_length(cvmx_cmd_queue_id_t queue_id);

/**
 * Return the command buffer to be written to. The purpose of this
 * function is to allow CVMX routine access t othe low level buffer
 * for initial hardware setup. User applications should not call this
 * function directly.
 *
 * @queue_id: Command queue to query
 *
 * Returns Command buffer or NULL on failure
 */
void *cvmx_cmd_queue_buffer(cvmx_cmd_queue_id_t queue_id);

/**
 * Get the index into the state arrays for the supplied queue id.
 *
 * @queue_id: Queue ID to get an index for
 *
 * Returns Index into the state arrays
 */
static inline int __cvmx_cmd_queue_get_index(cvmx_cmd_queue_id_t queue_id)
{
        /*
         * Warning: This code currently only works with devices that
         * have 256 queues or less. Devices with more than 16 queues
         * are layed out in memory to allow cores quick access to
         * every 16th queue. This reduces cache thrashing when you are
         * running 16 queues per port to support lockless operation.
         */
        int unit = queue_id >> 16;
        int q = (queue_id >> 4) & 0xf;
        int core = queue_id & 0xf;
        return unit * 256 + core * 16 + q;
}

/**
 * Lock the supplied queue so nobody else is updating it at the same
 * time as us.
 *
 * @queue_id: Queue ID to lock
 * @qptr:     Pointer to the queue's global state
 */
static inline void __cvmx_cmd_queue_lock(cvmx_cmd_queue_id_t queue_id,
                                         __cvmx_cmd_queue_state_t *qptr)
{
        extern __cvmx_cmd_queue_all_state_t
            *__cvmx_cmd_queue_state_ptr;
        int tmp;
        int my_ticket;
        prefetch(qptr);
        asm volatile (
                ".set push\n"
                ".set noreorder\n"
                "1:\n"
                /* Atomic add one to ticket_ptr */
                "ll     %[my_ticket], %[ticket_ptr]\n"
                /* and store the original value */
                "li     %[ticket], 1\n"
                /* in my_ticket */
                "baddu  %[ticket], %[my_ticket]\n"
                "sc     %[ticket], %[ticket_ptr]\n"
                "beqz   %[ticket], 1b\n"
                " nop\n"
                /* Load the current now_serving ticket */
                "lbu    %[ticket], %[now_serving]\n"
                "2:\n"
                /* Jump out if now_serving == my_ticket */
                "beq    %[ticket], %[my_ticket], 4f\n"
                /* Find out how many tickets are in front of me */
                " subu   %[ticket], %[my_ticket], %[ticket]\n"
                /* Use tickets in front of me minus one to delay */
                "subu  %[ticket], 1\n"
                /* Delay will be ((tickets in front)-1)*32 loops */
                "cins   %[ticket], %[ticket], 5, 7\n"
                "3:\n"
                /* Loop here until our ticket might be up */
                "bnez   %[ticket], 3b\n"
                " subu  %[ticket], 1\n"
                /* Jump back up to check out ticket again */
                "b      2b\n"
                /* Load the current now_serving ticket */
                " lbu   %[ticket], %[now_serving]\n"
                "4:\n"
                ".set pop\n" :
                [ticket_ptr] "=m"(__cvmx_cmd_queue_state_ptr->ticket[__cvmx_cmd_queue_get_index(queue_id)]),
                [now_serving] "=m"(qptr->now_serving), [ticket] "=r"(tmp),
                [my_ticket] "=r"(my_ticket)
            );
}

/**
 * Unlock the queue, flushing all writes.
 *
 * @qptr:   Queue to unlock
 */
static inline void __cvmx_cmd_queue_unlock(__cvmx_cmd_queue_state_t *qptr)
{
        qptr->now_serving++;
        CVMX_SYNCWS;
}

/**
 * Get the queue state structure for the given queue id
 *
 * @queue_id: Queue id to get
 *
 * Returns Queue structure or NULL on failure
 */
static inline __cvmx_cmd_queue_state_t
    *__cvmx_cmd_queue_get_state(cvmx_cmd_queue_id_t queue_id)
{
        extern __cvmx_cmd_queue_all_state_t
            *__cvmx_cmd_queue_state_ptr;
        return &__cvmx_cmd_queue_state_ptr->
            state[__cvmx_cmd_queue_get_index(queue_id)];
}

/**
 * Write an arbitrary number of command words to a command queue.
 * This is a generic function; the fixed number of comamnd word
 * functions yield higher performance.
 *
 * @queue_id:  Hardware command queue to write to
 * @use_locking:
 *                  Use internal locking to ensure exclusive access for queue
 *                  updates. If you don't use this locking you must ensure
 *                  exclusivity some other way. Locking is strongly recommended.
 * @cmd_count: Number of command words to write
 * @cmds:      Array of comamnds to write
 *
 * Returns CVMX_CMD_QUEUE_SUCCESS or a failure code
 */
static inline cvmx_cmd_queue_result_t cvmx_cmd_queue_write(cvmx_cmd_queue_id_t
                                                           queue_id,
                                                           int use_locking,
                                                           int cmd_count,
                                                           uint64_t *cmds)
{
        __cvmx_cmd_queue_state_t *qptr = __cvmx_cmd_queue_get_state(queue_id);

        /* Make sure nobody else is updating the same queue */
        if (likely(use_locking))
                __cvmx_cmd_queue_lock(queue_id, qptr);

        /*
         * If a max queue length was specified then make sure we don't
         * exceed it. If any part of the command would be below the
         * limit we allow it.
         */
        if (CVMX_CMD_QUEUE_ENABLE_MAX_DEPTH && unlikely(qptr->max_depth)) {
                if (unlikely
                    (cvmx_cmd_queue_length(queue_id) > (int)qptr->max_depth)) {
                        if (likely(use_locking))
                                __cvmx_cmd_queue_unlock(qptr);
                        return CVMX_CMD_QUEUE_FULL;
                }
        }

        /*
         * Normally there is plenty of room in the current buffer for
         * the command.
         */
        if (likely(qptr->index + cmd_count < qptr->pool_size_m1)) {
                uint64_t *ptr =
                    (uint64_t *) cvmx_phys_to_ptr((uint64_t) qptr->
                                                  base_ptr_div128 << 7);
                ptr += qptr->index;
                qptr->index += cmd_count;
                while (cmd_count--)
                        *ptr++ = *cmds++;
        } else {
                uint64_t *ptr;
                int count;
                /*
                 * We need a new comamnd buffer. Fail if there isn't
                 * one available.
                 */
                uint64_t *new_buffer =
                    (uint64_t *) cvmx_fpa_alloc(qptr->fpa_pool);
                if (unlikely(new_buffer == NULL)) {
                        if (likely(use_locking))
                                __cvmx_cmd_queue_unlock(qptr);
                        return CVMX_CMD_QUEUE_NO_MEMORY;
                }
                ptr =
                    (uint64_t *) cvmx_phys_to_ptr((uint64_t) qptr->
                                                  base_ptr_div128 << 7);
                /*
                 * Figure out how many command words will fit in this
                 * buffer. One location will be needed for the next
                 * buffer pointer.
                 */
                count = qptr->pool_size_m1 - qptr->index;
                ptr += qptr->index;
                cmd_count -= count;
                while (count--)
                        *ptr++ = *cmds++;
                *ptr = cvmx_ptr_to_phys(new_buffer);
                /*
                 * The current buffer is full and has a link to the
                 * next buffer. Time to write the rest of the commands
                 * into the new buffer.
                 */
                qptr->base_ptr_div128 = *ptr >> 7;
                qptr->index = cmd_count;
                ptr = new_buffer;
                while (cmd_count--)
                        *ptr++ = *cmds++;
        }

        /* All updates are complete. Release the lock and return */
        if (likely(use_locking))
                __cvmx_cmd_queue_unlock(qptr);
        return CVMX_CMD_QUEUE_SUCCESS;
}

/**
 * Simple function to write two command words to a command
 * queue.
 *
 * @queue_id: Hardware command queue to write to
 * @use_locking:
 *                 Use internal locking to ensure exclusive access for queue
 *                 updates. If you don't use this locking you must ensure
 *                 exclusivity some other way. Locking is strongly recommended.
 * @cmd1:     Command
 * @cmd2:     Command
 *
 * Returns CVMX_CMD_QUEUE_SUCCESS or a failure code
 */
static inline cvmx_cmd_queue_result_t cvmx_cmd_queue_write2(cvmx_cmd_queue_id_t
                                                            queue_id,
                                                            int use_locking,
                                                            uint64_t cmd1,
                                                            uint64_t cmd2)
{
        __cvmx_cmd_queue_state_t *qptr = __cvmx_cmd_queue_get_state(queue_id);

        /* Make sure nobody else is updating the same queue */
        if (likely(use_locking))
                __cvmx_cmd_queue_lock(queue_id, qptr);

        /*
         * If a max queue length was specified then make sure we don't
         * exceed it. If any part of the command would be below the
         * limit we allow it.
         */
        if (CVMX_CMD_QUEUE_ENABLE_MAX_DEPTH && unlikely(qptr->max_depth)) {
                if (unlikely
                    (cvmx_cmd_queue_length(queue_id) > (int)qptr->max_depth)) {
                        if (likely(use_locking))
                                __cvmx_cmd_queue_unlock(qptr);
                        return CVMX_CMD_QUEUE_FULL;
                }
        }

        /*
         * Normally there is plenty of room in the current buffer for
         * the command.
         */
        if (likely(qptr->index + 2 < qptr->pool_size_m1)) {
                uint64_t *ptr =
                    (uint64_t *) cvmx_phys_to_ptr((uint64_t) qptr->
                                                  base_ptr_div128 << 7);
                ptr += qptr->index;
                qptr->index += 2;
                ptr[0] = cmd1;
                ptr[1] = cmd2;
        } else {
                uint64_t *ptr;
                /*
                 * Figure out how many command words will fit in this
                 * buffer. One location will be needed for the next
                 * buffer pointer.
                 */
                int count = qptr->pool_size_m1 - qptr->index;
                /*
                 * We need a new comamnd buffer. Fail if there isn't
                 * one available.
                 */
                uint64_t *new_buffer =
                    (uint64_t *) cvmx_fpa_alloc(qptr->fpa_pool);
                if (unlikely(new_buffer == NULL)) {
                        if (likely(use_locking))
                                __cvmx_cmd_queue_unlock(qptr);
                        return CVMX_CMD_QUEUE_NO_MEMORY;
                }
                count--;
                ptr =
                    (uint64_t *) cvmx_phys_to_ptr((uint64_t) qptr->
                                                  base_ptr_div128 << 7);
                ptr += qptr->index;
                *ptr++ = cmd1;
                if (likely(count))
                        *ptr++ = cmd2;
                *ptr = cvmx_ptr_to_phys(new_buffer);
                /*
                 * The current buffer is full and has a link to the
                 * next buffer. Time to write the rest of the commands
                 * into the new buffer.
                 */
                qptr->base_ptr_div128 = *ptr >> 7;
                qptr->index = 0;
                if (unlikely(count == 0)) {
                        qptr->index = 1;
                        new_buffer[0] = cmd2;
                }
        }

        /* All updates are complete. Release the lock and return */
        if (likely(use_locking))
                __cvmx_cmd_queue_unlock(qptr);
        return CVMX_CMD_QUEUE_SUCCESS;
}

/**
 * Simple function to write three command words to a command
 * queue.
 *
 * @queue_id: Hardware command queue to write to
 * @use_locking:
 *                 Use internal locking to ensure exclusive access for queue
 *                 updates. If you don't use this locking you must ensure
 *                 exclusivity some other way. Locking is strongly recommended.
 * @cmd1:     Command
 * @cmd2:     Command
 * @cmd3:     Command
 *
 * Returns CVMX_CMD_QUEUE_SUCCESS or a failure code
 */
static inline cvmx_cmd_queue_result_t cvmx_cmd_queue_write3(cvmx_cmd_queue_id_t
                                                            queue_id,
                                                            int use_locking,
                                                            uint64_t cmd1,
                                                            uint64_t cmd2,
                                                            uint64_t cmd3)
{
        __cvmx_cmd_queue_state_t *qptr = __cvmx_cmd_queue_get_state(queue_id);

        /* Make sure nobody else is updating the same queue */
        if (likely(use_locking))
                __cvmx_cmd_queue_lock(queue_id, qptr);

        /*
         * If a max queue length was specified then make sure we don't
         * exceed it. If any part of the command would be below the
         * limit we allow it.
         */
        if (CVMX_CMD_QUEUE_ENABLE_MAX_DEPTH && unlikely(qptr->max_depth)) {
                if (unlikely
                    (cvmx_cmd_queue_length(queue_id) > (int)qptr->max_depth)) {
                        if (likely(use_locking))
                                __cvmx_cmd_queue_unlock(qptr);
                        return CVMX_CMD_QUEUE_FULL;
                }
        }

        /*
         * Normally there is plenty of room in the current buffer for
         * the command.
         */
        if (likely(qptr->index + 3 < qptr->pool_size_m1)) {
                uint64_t *ptr =
                    (uint64_t *) cvmx_phys_to_ptr((uint64_t) qptr->
                                                  base_ptr_div128 << 7);
                ptr += qptr->index;
                qptr->index += 3;
                ptr[0] = cmd1;
                ptr[1] = cmd2;
                ptr[2] = cmd3;
        } else {
                uint64_t *ptr;
                /*
                 * Figure out how many command words will fit in this
                 * buffer. One location will be needed for the next
                 * buffer pointer
                 */
                int count = qptr->pool_size_m1 - qptr->index;
                /*
                 * We need a new comamnd buffer. Fail if there isn't
                 * one available
                 */
                uint64_t *new_buffer =
                    (uint64_t *) cvmx_fpa_alloc(qptr->fpa_pool);
                if (unlikely(new_buffer == NULL)) {
                        if (likely(use_locking))
                                __cvmx_cmd_queue_unlock(qptr);
                        return CVMX_CMD_QUEUE_NO_MEMORY;
                }
                count--;
                ptr =
                    (uint64_t *) cvmx_phys_to_ptr((uint64_t) qptr->
                                                  base_ptr_div128 << 7);
                ptr += qptr->index;
                *ptr++ = cmd1;
                if (count) {
                        *ptr++ = cmd2;
                        if (count > 1)
                                *ptr++ = cmd3;
                }
                *ptr = cvmx_ptr_to_phys(new_buffer);
                /*
                 * The current buffer is full and has a link to the
                 * next buffer. Time to write the rest of the commands
                 * into the new buffer.
                 */
                qptr->base_ptr_div128 = *ptr >> 7;
                qptr->index = 0;
                ptr = new_buffer;
                if (count == 0) {
                        *ptr++ = cmd2;
                        qptr->index++;
                }
                if (count < 2) {
                        *ptr++ = cmd3;
                        qptr->index++;
                }
        }

        /* All updates are complete. Release the lock and return */
        if (likely(use_locking))
                __cvmx_cmd_queue_unlock(qptr);
        return CVMX_CMD_QUEUE_SUCCESS;
}

#endif /* __CVMX_CMD_QUEUE_H__ */