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

[mmotm.git] / drivers / staging / poch / poch.c

/*
 * User-space DMA and UIO based Redrapids Pocket Change CardBus driver
 *
 * Copyright 2008 Vijay Kumar <vijaykumar@bravegnu.org>
 *
 * Licensed under GPL version 2 only.
 */

#include <linux/device.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/uio_driver.h>
#include <linux/spinlock.h>
#include <linux/cdev.h>
#include <linux/delay.h>
#include <linux/sysfs.h>
#include <linux/poll.h>
#include <linux/idr.h>
#include <linux/interrupt.h>
#include <linux/init.h>
#include <linux/ioctl.h>
#include <linux/io.h>
#include <linux/sched.h>

#include "poch.h"

#include <asm/cacheflush.h>

#ifndef PCI_VENDOR_ID_RRAPIDS
#define PCI_VENDOR_ID_RRAPIDS 0x17D2
#endif

#ifndef PCI_DEVICE_ID_RRAPIDS_POCKET_CHANGE
#define PCI_DEVICE_ID_RRAPIDS_POCKET_CHANGE 0x0351
#endif

#define POCH_NCHANNELS 2

#define MAX_POCH_CARDS 8
#define MAX_POCH_DEVICES (MAX_POCH_CARDS * POCH_NCHANNELS)

#define DRV_NAME "poch"
#define PFX      DRV_NAME ": "

/*
 * BAR0 Bridge Register Definitions
 */

#define BRIDGE_REV_REG                  0x0
#define BRIDGE_INT_MASK_REG             0x4
#define BRIDGE_INT_STAT_REG             0x8

#define BRIDGE_INT_ACTIVE               (0x1 << 31)
#define BRIDGE_INT_FPGA                 (0x1 << 2)
#define BRIDGE_INT_TEMP_FAIL            (0x1 << 1)
#define BRIDGE_INT_TEMP_WARN            (0x1 << 0)

#define BRIDGE_FPGA_RESET_REG           0xC

#define BRIDGE_CARD_POWER_REG           0x10
#define BRIDGE_CARD_POWER_EN            (0x1 << 0)
#define BRIDGE_CARD_POWER_PROG_DONE     (0x1 << 31)

#define BRIDGE_JTAG_REG                 0x14
#define BRIDGE_DMA_GO_REG               0x18
#define BRIDGE_STAT_0_REG               0x1C
#define BRIDGE_STAT_1_REG               0x20
#define BRIDGE_STAT_2_REG               0x24
#define BRIDGE_STAT_3_REG               0x28
#define BRIDGE_TEMP_STAT_REG            0x2C
#define BRIDGE_TEMP_THRESH_REG          0x30
#define BRIDGE_EEPROM_REVSEL_REG        0x34
#define BRIDGE_CIS_STRUCT_REG           0x100
#define BRIDGE_BOARDREV_REG             0x124

/*
 * BAR1 FPGA Register Definitions
 */

#define FPGA_IFACE_REV_REG              0x0
#define FPGA_RX_BLOCK_SIZE_REG          0x8
#define FPGA_TX_BLOCK_SIZE_REG          0xC
#define FPGA_RX_BLOCK_COUNT_REG         0x10
#define FPGA_TX_BLOCK_COUNT_REG         0x14
#define FPGA_RX_CURR_DMA_BLOCK_REG      0x18
#define FPGA_TX_CURR_DMA_BLOCK_REG      0x1C
#define FPGA_RX_GROUP_COUNT_REG         0x20
#define FPGA_TX_GROUP_COUNT_REG         0x24
#define FPGA_RX_CURR_GROUP_REG          0x28
#define FPGA_TX_CURR_GROUP_REG          0x2C
#define FPGA_RX_CURR_PCI_REG            0x38
#define FPGA_TX_CURR_PCI_REG            0x3C
#define FPGA_RX_GROUP0_START_REG        0x40
#define FPGA_TX_GROUP0_START_REG        0xC0
#define FPGA_DMA_DESC_1_REG             0x140
#define FPGA_DMA_DESC_2_REG             0x144
#define FPGA_DMA_DESC_3_REG             0x148
#define FPGA_DMA_DESC_4_REG             0x14C

#define FPGA_DMA_INT_STAT_REG           0x150
#define FPGA_DMA_INT_MASK_REG           0x154
#define FPGA_DMA_INT_RX         (1 << 0)
#define FPGA_DMA_INT_TX         (1 << 1)

#define FPGA_RX_GROUPS_PER_INT_REG      0x158
#define FPGA_TX_GROUPS_PER_INT_REG      0x15C
#define FPGA_DMA_ADR_PAGE_REG           0x160
#define FPGA_FPGA_REV_REG               0x200

#define FPGA_ADC_CLOCK_CTL_REG          0x204
#define FPGA_ADC_CLOCK_CTL_OSC_EN       (0x1 << 3)
#define FPGA_ADC_CLOCK_LOCAL_CLK        (0x1 | FPGA_ADC_CLOCK_CTL_OSC_EN)
#define FPGA_ADC_CLOCK_EXT_SAMP_CLK     0X0

#define FPGA_ADC_DAC_EN_REG             0x208
#define FPGA_ADC_DAC_EN_DAC_OFF         (0x1 << 1)
#define FPGA_ADC_DAC_EN_ADC_OFF         (0x1 << 0)

#define FPGA_INT_STAT_REG               0x20C
#define FPGA_INT_MASK_REG               0x210
#define FPGA_INT_PLL_UNLOCKED           (0x1 << 9)
#define FPGA_INT_DMA_CORE               (0x1 << 8)
#define FPGA_INT_TX_FF_EMPTY            (0x1 << 7)
#define FPGA_INT_RX_FF_EMPTY            (0x1 << 6)
#define FPGA_INT_TX_FF_OVRFLW           (0x1 << 3)
#define FPGA_INT_RX_FF_OVRFLW           (0x1 << 2)
#define FPGA_INT_TX_ACQ_DONE            (0x1 << 1)
#define FPGA_INT_RX_ACQ_DONE            (0x1)

#define FPGA_RX_CTL_REG                 0x214
#define FPGA_RX_CTL_FIFO_FLUSH          (0x1 << 9)
#define FPGA_RX_CTL_SYNTH_DATA          (0x1 << 8)
#define FPGA_RX_CTL_CONT_CAP            (0x0 << 1)
#define FPGA_RX_CTL_SNAP_CAP            (0x1 << 1)

#define FPGA_RX_ARM_REG                 0x21C

#define FPGA_DOM_REG                    0x224
#define FPGA_DOM_DCM_RESET              (0x1 << 5)
#define FPGA_DOM_SOFT_RESET             (0x1 << 4)
#define FPGA_DOM_DUAL_M_SG_DMA          (0x0)
#define FPGA_DOM_TARGET_ACCESS          (0x1)

#define FPGA_TX_CTL_REG                 0x228
#define FPGA_TX_CTL_FIFO_FLUSH          (0x1 << 9)
#define FPGA_TX_CTL_OUTPUT_ZERO         (0x0 << 2)
#define FPGA_TX_CTL_OUTPUT_CARDBUS      (0x1 << 2)
#define FPGA_TX_CTL_OUTPUT_ADC          (0x2 << 2)
#define FPGA_TX_CTL_OUTPUT_SNAPSHOT     (0x3 << 2)
#define FPGA_TX_CTL_LOOPBACK            (0x1 << 0)

#define FPGA_ENDIAN_MODE_REG            0x22C
#define FPGA_RX_FIFO_COUNT_REG          0x28C
#define FPGA_TX_ENABLE_REG              0x298
#define FPGA_TX_TRIGGER_REG             0x29C
#define FPGA_TX_DATAMEM_COUNT_REG       0x2A8
#define FPGA_CAP_FIFO_REG               0x300
#define FPGA_TX_SNAPSHOT_REG            0x8000

/*
 * Channel Index Definitions
 */

enum {
        CHNO_RX_CHANNEL,
        CHNO_TX_CHANNEL,
};

struct poch_dev;

enum channel_dir {
        CHANNEL_DIR_RX,
        CHANNEL_DIR_TX,
};

struct poch_group_info {
        struct page *pg;
        dma_addr_t dma_addr;
        unsigned long user_offset;
};

struct channel_info {
        unsigned int chno;

        atomic_t sys_block_size;
        atomic_t sys_group_size;
        atomic_t sys_group_count;

        enum channel_dir dir;

        unsigned long block_size;
        unsigned long group_size;
        unsigned long group_count;

        /* Contains the DMA address and VM offset of each group. */
        struct poch_group_info *groups;

        /* Contains the header and circular buffer exported to userspace. */
        spinlock_t group_offsets_lock;
        struct poch_cbuf_header *header;
        struct page *header_pg;
        unsigned long header_size;

        /* Last group indicated as 'complete' to user space. */
        unsigned int transfer;

        wait_queue_head_t wq;

        union {
                unsigned int data_available;
                unsigned int space_available;
        };

        void __iomem *bridge_iomem;
        void __iomem *fpga_iomem;
        spinlock_t *iomem_lock;

        atomic_t free;
        atomic_t inited;

        /* Error counters */
        struct poch_counters counters;
        spinlock_t counters_lock;

        struct device *dev;
};

struct poch_dev {
        struct uio_info uio;
        struct pci_dev *pci_dev;
        unsigned int nchannels;
        struct channel_info channels[POCH_NCHANNELS];
        struct cdev cdev;

        /* Counts the no. of channels that have been opened. On first
         * open, the card is powered on. On last channel close, the
         * card is powered off.
         */
        atomic_t usage;

        void __iomem *bridge_iomem;
        void __iomem *fpga_iomem;
        spinlock_t iomem_lock;

        struct device *dev;
};

static dev_t poch_first_dev;
static struct class *poch_cls;
static DEFINE_IDR(poch_ids);

static ssize_t store_block_size(struct device *dev,
                                struct device_attribute *attr,
                                const char *buf, size_t count)
{
        struct channel_info *channel = dev_get_drvdata(dev);
        unsigned long block_size;

        sscanf(buf, "%lu", &block_size);
        atomic_set(&channel->sys_block_size, block_size);

        return count;
}
static DEVICE_ATTR(block_size, S_IWUSR|S_IWGRP, NULL, store_block_size);

static ssize_t store_group_size(struct device *dev,
                                struct device_attribute *attr,
                                const char *buf, size_t count)
{
        struct channel_info *channel = dev_get_drvdata(dev);
        unsigned long group_size;

        sscanf(buf, "%lu", &group_size);
        atomic_set(&channel->sys_group_size, group_size);

        return count;
}
static DEVICE_ATTR(group_size, S_IWUSR|S_IWGRP, NULL, store_group_size);

static ssize_t store_group_count(struct device *dev,
                                struct device_attribute *attr,
                                 const char *buf, size_t count)
{
        struct channel_info *channel = dev_get_drvdata(dev);
        unsigned long group_count;

        sscanf(buf, "%lu", &group_count);
        atomic_set(&channel->sys_group_count, group_count);

        return count;
}
static DEVICE_ATTR(group_count, S_IWUSR|S_IWGRP, NULL, store_group_count);

static ssize_t show_direction(struct device *dev,
                              struct device_attribute *attr, char *buf)
{
        struct channel_info *channel = dev_get_drvdata(dev);
        int len;

        len = sprintf(buf, "%s\n", (channel->dir ? "tx" : "rx"));
        return len;
}
static DEVICE_ATTR(dir, S_IRUSR|S_IRGRP, show_direction, NULL);

static unsigned long npages(unsigned long bytes)
{
        if (bytes % PAGE_SIZE == 0)
                return bytes / PAGE_SIZE;
        else
                return (bytes / PAGE_SIZE) + 1;
}

static ssize_t show_mmap_size(struct device *dev,
                              struct device_attribute *attr, char *buf)
{
        struct channel_info *channel = dev_get_drvdata(dev);
        int len;
        unsigned long mmap_size;
        unsigned long group_pages;
        unsigned long header_pages;
        unsigned long total_group_pages;

        group_pages = npages(channel->group_size);
        header_pages = npages(channel->header_size);
        total_group_pages = group_pages * channel->group_count;

        mmap_size = (header_pages + total_group_pages) * PAGE_SIZE;
        len = sprintf(buf, "%lu\n", mmap_size);
        return len;
}
static DEVICE_ATTR(mmap_size, S_IRUSR|S_IRGRP, show_mmap_size, NULL);

static struct device_attribute *poch_class_attrs[] = {
        &dev_attr_block_size,
        &dev_attr_group_size,
        &dev_attr_group_count,
        &dev_attr_dir,
        &dev_attr_mmap_size,
};

static void poch_channel_free_groups(struct channel_info *channel)
{
        unsigned long i;

        for (i = 0; i < channel->group_count; i++) {
                struct poch_group_info *group;
                unsigned int order;

                group = &channel->groups[i];
                order = get_order(channel->group_size);
                if (group->pg)
                        __free_pages(group->pg, order);
        }
}

static int poch_channel_alloc_groups(struct channel_info *channel)
{
        unsigned long i;
        unsigned long group_pages;
        unsigned long header_pages;

        group_pages = npages(channel->group_size);
        header_pages = npages(channel->header_size);

        for (i = 0; i < channel->group_count; i++) {
                struct poch_group_info *group;
                unsigned int order;
                gfp_t gfp_mask;

                group = &channel->groups[i];
                order = get_order(channel->group_size);

                /*
                 * __GFP_COMP is required here since we are going to
                 * perform non-linear mapping to userspace. For more
                 * information read the vm_insert_page() function
                 * comments.
                 */

                gfp_mask = GFP_KERNEL | GFP_DMA32 | __GFP_ZERO;
                group->pg = alloc_pages(gfp_mask, order);
                if (!group->pg) {
                        poch_channel_free_groups(channel);
                        return -ENOMEM;
                }

                /* FIXME: This is the physical address not the bus
                 * address!  This won't work in architectures that
                 * have an IOMMU. Can we use pci_map_single() for
                 * this?
                 */
                group->dma_addr = page_to_pfn(group->pg) * PAGE_SIZE;
                group->user_offset =
                        (header_pages + (i * group_pages)) * PAGE_SIZE;

                printk(KERN_INFO PFX "%ld: user_offset: 0x%lx\n", i,
                       group->user_offset);
        }

        return 0;
}

static int channel_latch_attr(struct channel_info *channel)
{
        channel->group_count = atomic_read(&channel->sys_group_count);
        channel->group_size = atomic_read(&channel->sys_group_size);
        channel->block_size = atomic_read(&channel->sys_block_size);

        if (channel->group_count == 0) {
                printk(KERN_ERR PFX "invalid group count %lu",
                       channel->group_count);
                return -EINVAL;
        }

        if (channel->group_size == 0 ||
            channel->group_size < channel->block_size) {
                printk(KERN_ERR PFX "invalid group size %lu",
                       channel->group_size);
                return -EINVAL;
        }

        if (channel->block_size == 0 || (channel->block_size % 8) != 0) {
                printk(KERN_ERR PFX "invalid block size %lu",
                       channel->block_size);
                return -EINVAL;
        }

        if (channel->group_size % channel->block_size != 0) {
                printk(KERN_ERR PFX
                       "group size should be multiple of block size");
                return -EINVAL;
        }

        return 0;
}

/*
 * Configure DMA group registers
 */
static void channel_dma_init(struct channel_info *channel)
{
        void __iomem *fpga = channel->fpga_iomem;
        u32 group_regs_base;
        u32 group_reg;
        unsigned int page;
        unsigned int group_in_page;
        unsigned long i;
        u32 block_size_reg;
        u32 block_count_reg;
        u32 group_count_reg;
        u32 groups_per_int_reg;
        u32 curr_pci_reg;

        if (channel->chno == CHNO_RX_CHANNEL) {
                group_regs_base = FPGA_RX_GROUP0_START_REG;
                block_size_reg = FPGA_RX_BLOCK_SIZE_REG;
                block_count_reg = FPGA_RX_BLOCK_COUNT_REG;
                group_count_reg = FPGA_RX_GROUP_COUNT_REG;
                groups_per_int_reg = FPGA_RX_GROUPS_PER_INT_REG;
                curr_pci_reg = FPGA_RX_CURR_PCI_REG;
        } else {
                group_regs_base = FPGA_TX_GROUP0_START_REG;
                block_size_reg = FPGA_TX_BLOCK_SIZE_REG;
                block_count_reg = FPGA_TX_BLOCK_COUNT_REG;
                group_count_reg = FPGA_TX_GROUP_COUNT_REG;
                groups_per_int_reg = FPGA_TX_GROUPS_PER_INT_REG;
                curr_pci_reg = FPGA_TX_CURR_PCI_REG;
        }

        printk(KERN_WARNING "block_size, group_size, group_count\n");
        /*
         * Block size is represented in no. of 64 bit transfers.
         */
        iowrite32(channel->block_size / 8, fpga + block_size_reg);
        iowrite32(channel->group_size / channel->block_size,
                  fpga + block_count_reg);
        iowrite32(channel->group_count, fpga + group_count_reg);
        /* FIXME: Hardcoded groups per int. Get it from sysfs? */
        iowrite32(1, fpga + groups_per_int_reg);

        /* Unlock PCI address? Not defined in the data sheet, but used
         * in the reference code by Redrapids.
         */
        iowrite32(0x1, fpga + curr_pci_reg);

        /* The DMA address page register is shared between the RX and
         * TX channels, so acquire lock.
         */
        for (i = 0; i < channel->group_count; i++) {
                page = i / 32;
                group_in_page = i % 32;

                group_reg = group_regs_base + (group_in_page * 4);

                spin_lock(channel->iomem_lock);
                iowrite32(page, fpga + FPGA_DMA_ADR_PAGE_REG);
                iowrite32(channel->groups[i].dma_addr, fpga + group_reg);
                spin_unlock(channel->iomem_lock);
        }

        for (i = 0; i < channel->group_count; i++) {
                page = i / 32;
                group_in_page = i % 32;

                group_reg = group_regs_base + (group_in_page * 4);

                spin_lock(channel->iomem_lock);
                iowrite32(page, fpga + FPGA_DMA_ADR_PAGE_REG);
                printk(KERN_INFO PFX "%ld: read dma_addr: 0x%x\n", i,
                       ioread32(fpga + group_reg));
                spin_unlock(channel->iomem_lock);
        }

}

static int poch_channel_alloc_header(struct channel_info *channel)
{
        struct poch_cbuf_header *header = channel->header;
        unsigned long group_offset_size;
        unsigned long tot_group_offsets_size;

        /* Allocate memory to hold header exported userspace */
        group_offset_size = sizeof(header->group_offsets[0]);
        tot_group_offsets_size = group_offset_size * channel->group_count;
        channel->header_size = sizeof(*header) + tot_group_offsets_size;
        channel->header_pg = alloc_pages(GFP_KERNEL | __GFP_ZERO,
                                         get_order(channel->header_size));
        if (!channel->header_pg)
                return -ENOMEM;

        channel->header = page_address(channel->header_pg);

        return 0;
}

static void poch_channel_free_header(struct channel_info *channel)
{
        unsigned int order;

        order = get_order(channel->header_size);
        __free_pages(channel->header_pg, order);
}

static void poch_channel_init_header(struct channel_info *channel)
{
        int i;
        struct poch_group_info *groups;
        s32 *group_offsets;

        channel->header->group_size_bytes = channel->group_size;
        channel->header->group_count = channel->group_count;

        spin_lock_init(&channel->group_offsets_lock);

        group_offsets = channel->header->group_offsets;
        groups = channel->groups;

        for (i = 0; i < channel->group_count; i++) {
                if (channel->dir == CHANNEL_DIR_RX)
                        group_offsets[i] = -1;
                else
                        group_offsets[i] = groups[i].user_offset;
        }
}

static void __poch_channel_clear_counters(struct channel_info *channel)
{
        channel->counters.pll_unlock = 0;
        channel->counters.fifo_empty = 0;
        channel->counters.fifo_overflow = 0;
}

static int poch_channel_init(struct channel_info *channel,
                             struct poch_dev *poch_dev)
{
        struct pci_dev *pdev = poch_dev->pci_dev;
        struct device *dev = &pdev->dev;
        unsigned long alloc_size;
        int ret;

        printk(KERN_WARNING "channel_latch_attr\n");

        ret = channel_latch_attr(channel);
        if (ret != 0)
                goto out;

        channel->transfer = 0;

        /* Allocate memory to hold group information. */
        alloc_size = channel->group_count * sizeof(struct poch_group_info);
        channel->groups = kzalloc(alloc_size, GFP_KERNEL);
        if (!channel->groups) {
                dev_err(dev, "error allocating memory for group info\n");
                ret = -ENOMEM;
                goto out;
        }

        printk(KERN_WARNING "poch_channel_alloc_groups\n");

        ret = poch_channel_alloc_groups(channel);
        if (ret) {
                dev_err(dev, "error allocating groups of order %d\n",
                        get_order(channel->group_size));
                goto out_free_group_info;
        }

        ret = poch_channel_alloc_header(channel);
        if (ret) {
                dev_err(dev, "error allocating user space header\n");
                goto out_free_groups;
        }

        channel->fpga_iomem = poch_dev->fpga_iomem;
        channel->bridge_iomem = poch_dev->bridge_iomem;
        channel->iomem_lock = &poch_dev->iomem_lock;
        spin_lock_init(&channel->counters_lock);

        __poch_channel_clear_counters(channel);

        printk(KERN_WARNING "poch_channel_init_header\n");

        poch_channel_init_header(channel);

        return 0;

 out_free_groups:
        poch_channel_free_groups(channel);
 out_free_group_info:
        kfree(channel->groups);
 out:
        return ret;
}

static int poch_wait_fpga_prog(void __iomem *bridge)
{
        unsigned long total_wait;
        const unsigned long wait_period = 100;
        /* FIXME: Get the actual timeout */
        const unsigned long prog_timeo = 10000; /* 10 Seconds */
        u32 card_power;

        printk(KERN_WARNING "poch_wait_fpg_prog\n");

        printk(KERN_INFO PFX "programming fpga ...\n");
        total_wait = 0;
        while (1) {
                msleep(wait_period);
                total_wait += wait_period;

                card_power = ioread32(bridge + BRIDGE_CARD_POWER_REG);
                if (card_power & BRIDGE_CARD_POWER_PROG_DONE) {
                        printk(KERN_INFO PFX "programming done\n");
                        return 0;
                }
                if (total_wait > prog_timeo) {
                        printk(KERN_ERR PFX
                               "timed out while programming FPGA\n");
                        return -EIO;
                }
        }
}

static void poch_card_power_off(struct poch_dev *poch_dev)
{
        void __iomem *bridge = poch_dev->bridge_iomem;
        u32 card_power;

        iowrite32(0, bridge + BRIDGE_INT_MASK_REG);
        iowrite32(0, bridge + BRIDGE_DMA_GO_REG);

        card_power = ioread32(bridge + BRIDGE_CARD_POWER_REG);
        iowrite32(card_power & ~BRIDGE_CARD_POWER_EN,
                  bridge + BRIDGE_CARD_POWER_REG);
}

enum clk_src {
        CLK_SRC_ON_BOARD,
        CLK_SRC_EXTERNAL
};

static void poch_card_clock_on(void __iomem *fpga)
{
        /* FIXME: Get this data through sysfs? */
        enum clk_src clk_src = CLK_SRC_ON_BOARD;

        if (clk_src == CLK_SRC_ON_BOARD) {
                iowrite32(FPGA_ADC_CLOCK_LOCAL_CLK | FPGA_ADC_CLOCK_CTL_OSC_EN,
                          fpga + FPGA_ADC_CLOCK_CTL_REG);
        } else if (clk_src == CLK_SRC_EXTERNAL) {
                iowrite32(FPGA_ADC_CLOCK_EXT_SAMP_CLK,
                          fpga + FPGA_ADC_CLOCK_CTL_REG);
        }
}

static int poch_card_power_on(struct poch_dev *poch_dev)
{
        void __iomem *bridge = poch_dev->bridge_iomem;
        void __iomem *fpga = poch_dev->fpga_iomem;

        iowrite32(BRIDGE_CARD_POWER_EN, bridge + BRIDGE_CARD_POWER_REG);

        if (poch_wait_fpga_prog(bridge) != 0) {
                poch_card_power_off(poch_dev);
                return -EIO;
        }

        poch_card_clock_on(fpga);

        /* Sync to new clock, reset state machines, set DMA mode. */
        iowrite32(FPGA_DOM_DCM_RESET | FPGA_DOM_SOFT_RESET
                  | FPGA_DOM_DUAL_M_SG_DMA, fpga + FPGA_DOM_REG);

        /* FIXME: The time required for sync. needs to be tuned. */
        msleep(1000);

        return 0;
}

static void poch_channel_analog_on(struct channel_info *channel)
{
        void __iomem *fpga = channel->fpga_iomem;
        u32 adc_dac_en;

        spin_lock(channel->iomem_lock);
        adc_dac_en = ioread32(fpga + FPGA_ADC_DAC_EN_REG);
        switch (channel->chno) {
        case CHNO_RX_CHANNEL:
                iowrite32(adc_dac_en & ~FPGA_ADC_DAC_EN_ADC_OFF,
                          fpga + FPGA_ADC_DAC_EN_REG);
                break;
        case CHNO_TX_CHANNEL:
                iowrite32(adc_dac_en & ~FPGA_ADC_DAC_EN_DAC_OFF,
                          fpga + FPGA_ADC_DAC_EN_REG);
                break;
        }
        spin_unlock(channel->iomem_lock);
}

static int poch_open(struct inode *inode, struct file *filp)
{
        struct poch_dev *poch_dev;
        struct channel_info *channel;
        void __iomem *bridge;
        void __iomem *fpga;
        int chno;
        int usage;
        int ret;

        poch_dev = container_of(inode->i_cdev, struct poch_dev, cdev);
        bridge = poch_dev->bridge_iomem;
        fpga = poch_dev->fpga_iomem;

        chno = iminor(inode) % poch_dev->nchannels;
        channel = &poch_dev->channels[chno];

        if (!atomic_dec_and_test(&channel->free)) {
                atomic_inc(&channel->free);
                ret = -EBUSY;
                goto out;
        }

        usage = atomic_inc_return(&poch_dev->usage);

        printk(KERN_WARNING "poch_card_power_on\n");

        if (usage == 1) {
                ret = poch_card_power_on(poch_dev);
                if (ret)
                        goto out_dec_usage;
        }

        printk(KERN_INFO "CardBus Bridge Revision: %x\n",
               ioread32(bridge + BRIDGE_REV_REG));
        printk(KERN_INFO "CardBus Interface Revision: %x\n",
               ioread32(fpga + FPGA_IFACE_REV_REG));

        channel->chno = chno;
        filp->private_data = channel;

        printk(KERN_WARNING "poch_channel_init\n");

        ret = poch_channel_init(channel, poch_dev);
        if (ret)
                goto out_power_off;

        poch_channel_analog_on(channel);

        printk(KERN_WARNING "channel_dma_init\n");

        channel_dma_init(channel);

        printk(KERN_WARNING "poch_channel_analog_on\n");

        if (usage == 1) {
                printk(KERN_WARNING "setting up DMA\n");

                /* Initialize DMA Controller. */
                iowrite32(FPGA_CAP_FIFO_REG, bridge + BRIDGE_STAT_2_REG);
                iowrite32(FPGA_DMA_DESC_1_REG, bridge + BRIDGE_STAT_3_REG);

                ioread32(fpga + FPGA_DMA_INT_STAT_REG);
                ioread32(fpga + FPGA_INT_STAT_REG);
                ioread32(bridge + BRIDGE_INT_STAT_REG);

                /* Initialize Interrupts. FIXME: Enable temperature
                 * handling We are enabling both Tx and Rx channel
                 * interrupts here. Do we need to enable interrupts
                 * only for the current channel? Anyways we won't get
                 * the interrupt unless the DMA is activated.
                 */
                iowrite32(BRIDGE_INT_FPGA, bridge + BRIDGE_INT_MASK_REG);
                iowrite32(FPGA_INT_DMA_CORE
                          | FPGA_INT_PLL_UNLOCKED
                          | FPGA_INT_TX_FF_EMPTY
                          | FPGA_INT_RX_FF_EMPTY
                          | FPGA_INT_TX_FF_OVRFLW
                          | FPGA_INT_RX_FF_OVRFLW,
                          fpga + FPGA_INT_MASK_REG);
                iowrite32(FPGA_DMA_INT_RX | FPGA_DMA_INT_TX,
                          fpga + FPGA_DMA_INT_MASK_REG);
        }

        if (channel->dir == CHANNEL_DIR_TX) {
                /* Flush TX FIFO and output data from cardbus. */
                iowrite32(FPGA_TX_CTL_FIFO_FLUSH
                          | FPGA_TX_CTL_OUTPUT_CARDBUS,
                          fpga + FPGA_TX_CTL_REG);
        } else {
                /* Flush RX FIFO and output data to cardbus. */
                iowrite32(FPGA_RX_CTL_CONT_CAP
                          | FPGA_RX_CTL_FIFO_FLUSH,
                          fpga + FPGA_RX_CTL_REG);
        }

        atomic_inc(&channel->inited);

        return 0;

 out_power_off:
        if (usage == 1)
                poch_card_power_off(poch_dev);
 out_dec_usage:
        atomic_dec(&poch_dev->usage);
        atomic_inc(&channel->free);
 out:
        return ret;
}

static int poch_release(struct inode *inode, struct file *filp)
{
        struct channel_info *channel = filp->private_data;
        struct poch_dev *poch_dev;
        int usage;

        poch_dev = container_of(inode->i_cdev, struct poch_dev, cdev);

        usage = atomic_dec_return(&poch_dev->usage);
        if (usage == 0) {
                printk(KERN_WARNING "poch_card_power_off\n");
                poch_card_power_off(poch_dev);
        }

        atomic_dec(&channel->inited);
        poch_channel_free_header(channel);
        poch_channel_free_groups(channel);
        kfree(channel->groups);
        atomic_inc(&channel->free);

        return 0;
}

/*
 * Map the header and the group buffers, to user space.
 */
static int poch_mmap(struct file *filp, struct vm_area_struct *vma)
{
        struct channel_info *channel = filp->private_data;

        unsigned long start;
        unsigned long size;

        unsigned long group_pages;
        unsigned long header_pages;
        unsigned long total_group_pages;

        int pg_num;
        struct page *pg;

        int i;
        int ret;

        printk(KERN_WARNING "poch_mmap\n");

        if (vma->vm_pgoff) {
                printk(KERN_WARNING PFX "page offset: %lu\n", vma->vm_pgoff);
                return -EINVAL;
        }

        group_pages = npages(channel->group_size);
        header_pages = npages(channel->header_size);
        total_group_pages = group_pages * channel->group_count;

        size = vma->vm_end - vma->vm_start;
        if (size != (header_pages + total_group_pages) * PAGE_SIZE) {
                printk(KERN_WARNING PFX "required %lu bytes\n", size);
                return -EINVAL;
        }

        start = vma->vm_start;

        /* FIXME: Cleanup required on failure? */
        pg = channel->header_pg;
        for (pg_num = 0; pg_num < header_pages; pg_num++, pg++) {
                printk(KERN_DEBUG PFX "page_count: %d\n", page_count(pg));
                printk(KERN_DEBUG PFX "%d: header: 0x%lx\n", pg_num, start);
                ret = vm_insert_page(vma, start, pg);
                if (ret) {
                        printk(KERN_DEBUG "vm_insert 1 failed at %lx\n", start);
                        return ret;
                }
                start += PAGE_SIZE;
        }

        for (i = 0; i < channel->group_count; i++) {
                pg = channel->groups[i].pg;
                for (pg_num = 0; pg_num < group_pages; pg_num++, pg++) {
                        printk(KERN_DEBUG PFX "%d: group %d: 0x%lx\n",
                               pg_num, i, start);
                        ret = vm_insert_page(vma, start, pg);
                        if (ret) {
                                printk(KERN_DEBUG PFX
                                       "vm_insert 2 failed at %d\n", pg_num);
                                return ret;
                        }
                        start += PAGE_SIZE;
                }
        }

        return 0;
}

/*
 * Check whether there is some group that the user space has not
 * consumed yet. When the user space consumes a group, it sets it to
 * -1. Cosuming could be reading data in case of RX and filling a
 * buffer in case of TX.
 */
static int poch_channel_available(struct channel_info *channel)
{
        int i;

        spin_lock_irq(&channel->group_offsets_lock);

        for (i = 0; i < channel->group_count; i++) {
                if (channel->header->group_offsets[i] != -1) {
                        spin_unlock_irq(&channel->group_offsets_lock);
                        return 1;
                }
        }

        spin_unlock_irq(&channel->group_offsets_lock);

        return 0;
}

static unsigned int poch_poll(struct file *filp, poll_table *pt)
{
        struct channel_info *channel = filp->private_data;
        unsigned int ret = 0;

        poll_wait(filp, &channel->wq, pt);

        if (poch_channel_available(channel)) {
                if (channel->dir == CHANNEL_DIR_RX)
                        ret = POLLIN | POLLRDNORM;
                else
                        ret = POLLOUT | POLLWRNORM;
        }

        return ret;
}

static int poch_ioctl(struct inode *inode, struct file *filp,
                      unsigned int cmd, unsigned long arg)
{
        struct channel_info *channel = filp->private_data;
        void __iomem *fpga = channel->fpga_iomem;
        void __iomem *bridge = channel->bridge_iomem;
        void __user *argp = (void __user *)arg;
        struct vm_area_struct *vms;
        struct poch_counters counters;
        int ret;

        switch (cmd) {
        case POCH_IOC_TRANSFER_START:
                switch (channel->chno) {
                case CHNO_TX_CHANNEL:
                        printk(KERN_INFO PFX "ioctl: Tx start\n");
                        iowrite32(0x1, fpga + FPGA_TX_TRIGGER_REG);
                        iowrite32(0x1, fpga + FPGA_TX_ENABLE_REG);

                        /* FIXME: Does it make sense to do a DMA GO
                         * twice, once in Tx and once in Rx.
                         */
                        iowrite32(0x1, bridge + BRIDGE_DMA_GO_REG);
                        break;
                case CHNO_RX_CHANNEL:
                        printk(KERN_INFO PFX "ioctl: Rx start\n");
                        iowrite32(0x1, fpga + FPGA_RX_ARM_REG);
                        iowrite32(0x1, bridge + BRIDGE_DMA_GO_REG);
                        break;
                }
                break;
        case POCH_IOC_TRANSFER_STOP:
                switch (channel->chno) {
                case CHNO_TX_CHANNEL:
                        printk(KERN_INFO PFX "ioctl: Tx stop\n");
                        iowrite32(0x0, fpga + FPGA_TX_ENABLE_REG);
                        iowrite32(0x0, fpga + FPGA_TX_TRIGGER_REG);
                        iowrite32(0x0, bridge + BRIDGE_DMA_GO_REG);
                        break;
                case CHNO_RX_CHANNEL:
                        printk(KERN_INFO PFX "ioctl: Rx stop\n");
                        iowrite32(0x0, fpga + FPGA_RX_ARM_REG);
                        iowrite32(0x0, bridge + BRIDGE_DMA_GO_REG);
                        break;
                }
                break;
        case POCH_IOC_GET_COUNTERS:
                if (!access_ok(VERIFY_WRITE, argp, sizeof(struct poch_counters)))
                        return -EFAULT;

                spin_lock_irq(&channel->counters_lock);
                counters = channel->counters;
                __poch_channel_clear_counters(channel);
                spin_unlock_irq(&channel->counters_lock);

                ret = copy_to_user(argp, &counters,
                                   sizeof(struct poch_counters));
                if (ret)
                        return ret;

                break;
        case POCH_IOC_SYNC_GROUP_FOR_USER:
        case POCH_IOC_SYNC_GROUP_FOR_DEVICE:
                vms = find_vma(current->mm, arg);
                if (!vms)
                        /* Address not mapped. */
                        return -EINVAL;
                if (vms->vm_file != filp)
                        /* Address mapped from different device/file. */
                        return -EINVAL;

                flush_cache_range(vms, arg, arg + channel->group_size);
                break;
        }
        return 0;
}

static struct file_operations poch_fops = {
        .owner = THIS_MODULE,
        .open = poch_open,
        .release = poch_release,
        .ioctl = poch_ioctl,
        .poll = poch_poll,
        .mmap = poch_mmap
};

static void poch_irq_dma(struct channel_info *channel)
{
        u32 prev_transfer;
        u32 curr_transfer;
        long groups_done;
        unsigned long i, j;
        struct poch_group_info *groups;
        s32 *group_offsets;
        u32 curr_group_reg;

        if (!atomic_read(&channel->inited))
                return;

        prev_transfer = channel->transfer;

        if (channel->chno == CHNO_RX_CHANNEL)
                curr_group_reg = FPGA_RX_CURR_GROUP_REG;
        else
                curr_group_reg = FPGA_TX_CURR_GROUP_REG;

        curr_transfer = ioread32(channel->fpga_iomem + curr_group_reg);

        groups_done = curr_transfer - prev_transfer;
        /* Check wrap over, and handle it. */
        if (groups_done <= 0)
                groups_done += channel->group_count;

        group_offsets = channel->header->group_offsets;
        groups = channel->groups;

        spin_lock(&channel->group_offsets_lock);

        for (i = 0; i < groups_done; i++) {
                j = (prev_transfer + i) % channel->group_count;
                group_offsets[j] = groups[j].user_offset;
        }

        spin_unlock(&channel->group_offsets_lock);

        channel->transfer = curr_transfer;

        wake_up_interruptible(&channel->wq);
}

static irqreturn_t poch_irq_handler(int irq, void *p)
{
        struct poch_dev *poch_dev = p;
        void __iomem *bridge = poch_dev->bridge_iomem;
        void __iomem *fpga = poch_dev->fpga_iomem;
        struct channel_info *channel_rx = &poch_dev->channels[CHNO_RX_CHANNEL];
        struct channel_info *channel_tx = &poch_dev->channels[CHNO_TX_CHANNEL];
        u32 bridge_stat;
        u32 fpga_stat;
        u32 dma_stat;

        bridge_stat = ioread32(bridge + BRIDGE_INT_STAT_REG);
        fpga_stat = ioread32(fpga + FPGA_INT_STAT_REG);
        dma_stat = ioread32(fpga + FPGA_DMA_INT_STAT_REG);

        ioread32(fpga + FPGA_DMA_INT_STAT_REG);
        ioread32(fpga + FPGA_INT_STAT_REG);
        ioread32(bridge + BRIDGE_INT_STAT_REG);

        if (bridge_stat & BRIDGE_INT_FPGA) {
                if (fpga_stat & FPGA_INT_DMA_CORE) {
                        if (dma_stat & FPGA_DMA_INT_RX)
                                poch_irq_dma(channel_rx);
                        if (dma_stat & FPGA_DMA_INT_TX)
                                poch_irq_dma(channel_tx);
                }
                if (fpga_stat & FPGA_INT_PLL_UNLOCKED) {
                        channel_tx->counters.pll_unlock++;
                        channel_rx->counters.pll_unlock++;
                        if (printk_ratelimit())
                                printk(KERN_WARNING PFX "PLL unlocked\n");
                }
                if (fpga_stat & FPGA_INT_TX_FF_EMPTY)
                        channel_tx->counters.fifo_empty++;
                if (fpga_stat & FPGA_INT_TX_FF_OVRFLW)
                        channel_tx->counters.fifo_overflow++;
                if (fpga_stat & FPGA_INT_RX_FF_EMPTY)
                        channel_rx->counters.fifo_empty++;
                if (fpga_stat & FPGA_INT_RX_FF_OVRFLW)
                        channel_rx->counters.fifo_overflow++;

                /*
                 * FIXME: These errors should be notified through the
                 * poll interface as POLLERR.
                 */

                /* Re-enable interrupts. */
                iowrite32(BRIDGE_INT_FPGA, bridge + BRIDGE_INT_MASK_REG);

                return IRQ_HANDLED;
        }

        return IRQ_NONE;
}

static void poch_class_dev_unregister(struct poch_dev *poch_dev, int id)
{
        int i, j;
        int nattrs;
        struct channel_info *channel;
        dev_t devno;

        if (poch_dev->dev == NULL)
                return;

        for (i = 0; i < poch_dev->nchannels; i++) {
                channel = &poch_dev->channels[i];
                devno = poch_first_dev + (id * poch_dev->nchannels) + i;

                if (!channel->dev)
                        continue;

                nattrs = sizeof(poch_class_attrs)/sizeof(poch_class_attrs[0]);
                for (j = 0; j < nattrs; j++)
                        device_remove_file(channel->dev, poch_class_attrs[j]);

                device_unregister(channel->dev);
        }

        device_unregister(poch_dev->dev);
}

static int __devinit poch_class_dev_register(struct poch_dev *poch_dev,
                                             int id)
{
        struct device *dev = &poch_dev->pci_dev->dev;
        int i, j;
        int nattrs;
        int ret;
        struct channel_info *channel;
        dev_t devno;

        poch_dev->dev = device_create(poch_cls, &poch_dev->pci_dev->dev,
                                      MKDEV(0, 0), NULL, "poch%d", id);
        if (IS_ERR(poch_dev->dev)) {
                dev_err(dev, "error creating parent class device");
                ret = PTR_ERR(poch_dev->dev);
                poch_dev->dev = NULL;
                return ret;
        }

        for (i = 0; i < poch_dev->nchannels; i++) {
                channel = &poch_dev->channels[i];

                devno = poch_first_dev + (id * poch_dev->nchannels) + i;
                channel->dev = device_create(poch_cls, poch_dev->dev, devno,
                                             NULL, "ch%d", i);
                if (IS_ERR(channel->dev)) {
                        dev_err(dev, "error creating channel class device");
                        ret = PTR_ERR(channel->dev);
                        channel->dev = NULL;
                        poch_class_dev_unregister(poch_dev, id);
                        return ret;
                }

                dev_set_drvdata(channel->dev, channel);
                nattrs = sizeof(poch_class_attrs)/sizeof(poch_class_attrs[0]);
                for (j = 0; j < nattrs; j++) {
                        ret = device_create_file(channel->dev,
                                                 poch_class_attrs[j]);
                        if (ret) {
                                dev_err(dev, "error creating attribute file");
                                poch_class_dev_unregister(poch_dev, id);
                                return ret;
                        }
                }
        }

        return 0;
}

static int __devinit poch_pci_probe(struct pci_dev *pdev,
                                    const struct pci_device_id *pci_id)
{
        struct device *dev = &pdev->dev;
        struct poch_dev *poch_dev;
        struct uio_info *uio;
        int ret;
        int id;
        int i;

        poch_dev = kzalloc(sizeof(struct poch_dev), GFP_KERNEL);
        if (!poch_dev) {
                dev_err(dev, "error allocating priv. data memory\n");
                return -ENOMEM;
        }

        poch_dev->pci_dev = pdev;
        uio = &poch_dev->uio;

        pci_set_drvdata(pdev, poch_dev);

        spin_lock_init(&poch_dev->iomem_lock);

        poch_dev->nchannels = POCH_NCHANNELS;
        poch_dev->channels[CHNO_RX_CHANNEL].dir = CHANNEL_DIR_RX;
        poch_dev->channels[CHNO_TX_CHANNEL].dir = CHANNEL_DIR_TX;

        for (i = 0; i < poch_dev->nchannels; i++) {
                init_waitqueue_head(&poch_dev->channels[i].wq);
                atomic_set(&poch_dev->channels[i].free, 1);
                atomic_set(&poch_dev->channels[i].inited, 0);
        }

        ret = pci_enable_device(pdev);
        if (ret) {
                dev_err(dev, "error enabling device\n");
                goto out_free;
        }

        ret = pci_request_regions(pdev, "poch");
        if (ret) {
                dev_err(dev, "error requesting resources\n");
                goto out_disable;
        }

        uio->mem[0].addr = pci_resource_start(pdev, 1);
        if (!uio->mem[0].addr) {
                dev_err(dev, "invalid BAR1\n");
                ret = -ENODEV;
                goto out_release;
        }

        uio->mem[0].size = pci_resource_len(pdev, 1);
        uio->mem[0].memtype = UIO_MEM_PHYS;

        uio->name = "poch";
        uio->version = "0.0.1";
        uio->irq = -1;
        ret = uio_register_device(dev, uio);
        if (ret) {
                dev_err(dev, "error register UIO device: %d\n", ret);
                goto out_release;
        }

        poch_dev->bridge_iomem = ioremap(pci_resource_start(pdev, 0),
                                         pci_resource_len(pdev, 0));
        if (poch_dev->bridge_iomem == NULL) {
                dev_err(dev, "error mapping bridge (bar0) registers\n");
                ret = -ENOMEM;
                goto out_uio_unreg;
        }

        poch_dev->fpga_iomem = ioremap(pci_resource_start(pdev, 1),
                                       pci_resource_len(pdev, 1));
        if (poch_dev->fpga_iomem == NULL) {
                dev_err(dev, "error mapping fpga (bar1) registers\n");
                ret = -ENOMEM;
                goto out_bar0_unmap;
        }

        ret = request_irq(pdev->irq, poch_irq_handler, IRQF_SHARED,
                          dev_name(dev), poch_dev);
        if (ret) {
                dev_err(dev, "error requesting IRQ %u\n", pdev->irq);
                ret = -ENOMEM;
                goto out_bar1_unmap;
        }

        if (!idr_pre_get(&poch_ids, GFP_KERNEL)) {
                dev_err(dev, "error allocating memory ids\n");
                ret = -ENOMEM;
                goto out_free_irq;
        }

        idr_get_new(&poch_ids, poch_dev, &id);
        if (id >= MAX_POCH_CARDS) {
                dev_err(dev, "minors exhausted\n");
                ret = -EBUSY;
                goto out_free_irq;
        }

        cdev_init(&poch_dev->cdev, &poch_fops);
        poch_dev->cdev.owner = THIS_MODULE;
        ret = cdev_add(&poch_dev->cdev,
                       poch_first_dev + (id * poch_dev->nchannels),
                       poch_dev->nchannels);
        if (ret) {
                dev_err(dev, "error register character device\n");
                goto out_idr_remove;
        }

        ret = poch_class_dev_register(poch_dev, id);
        if (ret)
                goto out_cdev_del;

        return 0;

 out_cdev_del:
        cdev_del(&poch_dev->cdev);
 out_idr_remove:
        idr_remove(&poch_ids, id);
 out_free_irq:
        free_irq(pdev->irq, poch_dev);
 out_bar1_unmap:
        iounmap(poch_dev->fpga_iomem);
 out_bar0_unmap:
        iounmap(poch_dev->bridge_iomem);
 out_uio_unreg:
        uio_unregister_device(uio);
 out_release:
        pci_release_regions(pdev);
 out_disable:
        pci_disable_device(pdev);
 out_free:
        kfree(poch_dev);
        return ret;
}

/*
 * FIXME: We are yet to handle the hot unplug case.
 */
static void poch_pci_remove(struct pci_dev *pdev)
{
        struct poch_dev *poch_dev = pci_get_drvdata(pdev);
        struct uio_info *uio = &poch_dev->uio;
        unsigned int minor = MINOR(poch_dev->cdev.dev);
        unsigned int id = minor / poch_dev->nchannels;

        poch_class_dev_unregister(poch_dev, id);
        cdev_del(&poch_dev->cdev);
        idr_remove(&poch_ids, id);
        free_irq(pdev->irq, poch_dev);
        iounmap(poch_dev->fpga_iomem);
        iounmap(poch_dev->bridge_iomem);
        uio_unregister_device(uio);
        pci_release_regions(pdev);
        pci_disable_device(pdev);
        pci_set_drvdata(pdev, NULL);
        iounmap(uio->mem[0].internal_addr);

        kfree(poch_dev);
}

static const struct pci_device_id poch_pci_ids[] /* __devinitconst */ = {
        { PCI_DEVICE(PCI_VENDOR_ID_RRAPIDS,
                     PCI_DEVICE_ID_RRAPIDS_POCKET_CHANGE) },
        { 0, }
};

static struct pci_driver poch_pci_driver = {
        .name = DRV_NAME,
        .id_table = poch_pci_ids,
        .probe = poch_pci_probe,
        .remove = poch_pci_remove,
};

static int __init poch_init_module(void)
{
        int ret = 0;

        ret = alloc_chrdev_region(&poch_first_dev, 0,
                                  MAX_POCH_DEVICES, DRV_NAME);
        if (ret) {
                printk(KERN_ERR PFX "error allocating device no.");
                return ret;
        }

        poch_cls = class_create(THIS_MODULE, "pocketchange");
        if (IS_ERR(poch_cls)) {
                ret = PTR_ERR(poch_cls);
                goto out_unreg_chrdev;
        }

        ret = pci_register_driver(&poch_pci_driver);
        if (ret) {
                printk(KERN_ERR PFX "error register PCI device");
                goto out_class_destroy;
        }

        return 0;

 out_class_destroy:
        class_destroy(poch_cls);

 out_unreg_chrdev:
        unregister_chrdev_region(poch_first_dev, MAX_POCH_DEVICES);

        return ret;
}

static void __exit poch_exit_module(void)
{
        pci_unregister_driver(&poch_pci_driver);
        class_destroy(poch_cls);
        unregister_chrdev_region(poch_first_dev, MAX_POCH_DEVICES);
}

module_init(poch_init_module);
module_exit(poch_exit_module);

MODULE_LICENSE("GPL v2");