spi-pxa2xx.c

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/*
 * Copyright (C) 2005 Stephen Street / StreetFire Sound Labs
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/ioport.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
#include <linux/spi/pxa2xx_spi.h>
#include <linux/dma-mapping.h>
#include <linux/spi/spi.h>
#include <linux/workqueue.h>
#include <linux/delay.h>
#include <linux/gpio.h>
#include <linux/slab.h>

#include <asm/io.h>
#include <asm/irq.h>
#include <asm/delay.h>


MODULE_AUTHOR("Stephen Street");
MODULE_DESCRIPTION("PXA2xx SSP SPI Controller");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:pxa2xx-spi");

#define MAX_BUSES 3

#define TIMOUT_DFLT     1000

#define DMA_INT_MASK        (DCSR_ENDINTR | DCSR_STARTINTR | DCSR_BUSERR)
#define RESET_DMA_CHANNEL   (DCSR_NODESC | DMA_INT_MASK)
#define IS_DMA_ALIGNED(x)   ((((u32)(x)) & 0x07) == 0)
#define MAX_DMA_LEN     8191
#define DMA_ALIGNMENT       8

/*
 * for testing SSCR1 changes that require SSP restart, basically
 * everything except the service and interrupt enables, the pxa270 developer
 * manual says only SSCR1_SCFR, SSCR1_SPH, SSCR1_SPO need to be in this
 * list, but the PXA255 dev man says all bits without really meaning the
 * service and interrupt enables
 */
#define SSCR1_CHANGE_MASK (SSCR1_TTELP | SSCR1_TTE | SSCR1_SCFR \
                | SSCR1_ECRA | SSCR1_ECRB | SSCR1_SCLKDIR \
                | SSCR1_SFRMDIR | SSCR1_RWOT | SSCR1_TRAIL \
                | SSCR1_IFS | SSCR1_STRF | SSCR1_EFWR \
                | SSCR1_RFT | SSCR1_TFT | SSCR1_MWDS \
                | SSCR1_SPH | SSCR1_SPO | SSCR1_LBM)

#define DEFINE_SSP_REG(reg, off) \
static inline u32 read_##reg(void const __iomem *p) \
{ return __raw_readl(p + (off)); } \
\
static inline void write_##reg(u32 v, void __iomem *p) \
{ __raw_writel(v, p + (off)); }

DEFINE_SSP_REG(SSCR0, 0x00)
DEFINE_SSP_REG(SSCR1, 0x04)
DEFINE_SSP_REG(SSSR, 0x08)
DEFINE_SSP_REG(SSITR, 0x0c)
DEFINE_SSP_REG(SSDR, 0x10)
DEFINE_SSP_REG(SSTO, 0x28)
DEFINE_SSP_REG(SSPSP, 0x2c)

#define START_STATE ((void*)0)
#define RUNNING_STATE ((void*)1)
#define DONE_STATE ((void*)2)
#define ERROR_STATE ((void*)-1)

#define QUEUE_RUNNING 0
#define QUEUE_STOPPED 1

struct driver_data {
    /* Driver model hookup */
    struct platform_device *pdev;

    /* SSP Info */
    struct ssp_device *ssp;

    /* SPI framework hookup */
    enum pxa_ssp_type ssp_type;
    struct spi_master *master;

    /* PXA hookup */
    struct pxa2xx_spi_master *master_info;

    /* DMA setup stuff */
    int rx_channel;
    int tx_channel;
    u32 *null_dma_buf;

    /* SSP register addresses */
    void __iomem *ioaddr;
    u32 ssdr_physical;

    /* SSP masks*/
    u32 dma_cr1;
    u32 int_cr1;
    u32 clear_sr;
    u32 mask_sr;

    /* Driver message queue */
    struct workqueue_struct *workqueue;
    struct work_struct pump_messages;
    spinlock_t lock;
    struct list_head queue;
    int busy;
    int run;

    /* Message Transfer pump */
    struct tasklet_struct pump_transfers;

    /* Current message transfer state info */
    struct spi_message* cur_msg;
    struct spi_transfer* cur_transfer;
    struct chip_data *cur_chip;
    size_t len;
    void *tx;
    void *tx_end;
    void *rx;
    void *rx_end;
    int dma_mapped;
    dma_addr_t rx_dma;
    dma_addr_t tx_dma;
    size_t rx_map_len;
    size_t tx_map_len;
    u8 n_bytes;
    u32 dma_width;
    int (*write)(struct driver_data *drv_data);
    int (*read)(struct driver_data *drv_data);
    irqreturn_t (*transfer_handler)(struct driver_data *drv_data);
    void (*cs_control)(u32 command);
};

struct chip_data {
    u32 cr0;
    u32 cr1;
    u32 psp;
    u32 timeout;
    u8 n_bytes;
    u32 dma_width;
    u32 dma_burst_size;
    u32 threshold;
    u32 dma_threshold;
    u8 enable_dma;
    u8 bits_per_word;
    u32 speed_hz;
    union {
        int gpio_cs;
        unsigned int frm;
    };
    int gpio_cs_inverted;
    int (*write)(struct driver_data *drv_data);
    int (*read)(struct driver_data *drv_data);
    void (*cs_control)(u32 command);
};

static void pump_messages(struct work_struct *work);

static void cs_assert(struct driver_data *drv_data)
{
    struct chip_data *chip = drv_data->cur_chip;

    if (drv_data->ssp_type == CE4100_SSP) {
        write_SSSR(drv_data->cur_chip->frm, drv_data->ioaddr);
        return;
    }

    if (chip->cs_control) {
        chip->cs_control(PXA2XX_CS_ASSERT);
        return;
    }

    if (gpio_is_valid(chip->gpio_cs))
        gpio_set_value(chip->gpio_cs, chip->gpio_cs_inverted);
}

static void cs_deassert(struct driver_data *drv_data)
{
    struct chip_data *chip = drv_data->cur_chip;

    if (drv_data->ssp_type == CE4100_SSP)
        return;

    if (chip->cs_control) {
        chip->cs_control(PXA2XX_CS_DEASSERT);
        return;
    }

    if (gpio_is_valid(chip->gpio_cs))
        gpio_set_value(chip->gpio_cs, !chip->gpio_cs_inverted);
}

static void write_SSSR_CS(struct driver_data *drv_data, u32 val)
{
    void __iomem *reg = drv_data->ioaddr;

    if (drv_data->ssp_type == CE4100_SSP)
        val |= read_SSSR(reg) & SSSR_ALT_FRM_MASK;

    write_SSSR(val, reg);
}

static int pxa25x_ssp_comp(struct driver_data *drv_data)
{
    if (drv_data->ssp_type == PXA25x_SSP)
        return 1;
    if (drv_data->ssp_type == CE4100_SSP)
        return 1;
    return 0;
}

static int flush(struct driver_data *drv_data)
{
    unsigned long limit = loops_per_jiffy << 1;

    void __iomem *reg = drv_data->ioaddr;

    do {
        while (read_SSSR(reg) & SSSR_RNE) {
            read_SSDR(reg);
        }
    } while ((read_SSSR(reg) & SSSR_BSY) && --limit);
    write_SSSR_CS(drv_data, SSSR_ROR);

    return limit;
}

static int null_writer(struct driver_data *drv_data)
{
    void __iomem *reg = drv_data->ioaddr;
    u8 n_bytes = drv_data->n_bytes;

    if (((read_SSSR(reg) & SSSR_TFL_MASK) == SSSR_TFL_MASK)
        || (drv_data->tx == drv_data->tx_end))
        return 0;

    write_SSDR(0, reg);
    drv_data->tx += n_bytes;

    return 1;
}

static int null_reader(struct driver_data *drv_data)
{
    void __iomem *reg = drv_data->ioaddr;
    u8 n_bytes = drv_data->n_bytes;

    while ((read_SSSR(reg) & SSSR_RNE)
        && (drv_data->rx < drv_data->rx_end)) {
        read_SSDR(reg);
        drv_data->rx += n_bytes;
    }

    return drv_data->rx == drv_data->rx_end;
}

static int u8_writer(struct driver_data *drv_data)
{
    void __iomem *reg = drv_data->ioaddr;

    if (((read_SSSR(reg) & SSSR_TFL_MASK) == SSSR_TFL_MASK)
        || (drv_data->tx == drv_data->tx_end))
        return 0;

    write_SSDR(*(u8 *)(drv_data->tx), reg);
    ++drv_data->tx;

    return 1;
}

static int u8_reader(struct driver_data *drv_data)
{
    void __iomem *reg = drv_data->ioaddr;

    while ((read_SSSR(reg) & SSSR_RNE)
        && (drv_data->rx < drv_data->rx_end)) {
        *(u8 *)(drv_data->rx) = read_SSDR(reg);
        ++drv_data->rx;
    }

    return drv_data->rx == drv_data->rx_end;
}

static int u16_writer(struct driver_data *drv_data)
{
    void __iomem *reg = drv_data->ioaddr;

    if (((read_SSSR(reg) & SSSR_TFL_MASK) == SSSR_TFL_MASK)
        || (drv_data->tx == drv_data->tx_end))
        return 0;

    write_SSDR(*(u16 *)(drv_data->tx), reg);
    drv_data->tx += 2;

    return 1;
}

static int u16_reader(struct driver_data *drv_data)
{
    void __iomem *reg = drv_data->ioaddr;

    while ((read_SSSR(reg) & SSSR_RNE)
        && (drv_data->rx < drv_data->rx_end)) {
        *(u16 *)(drv_data->rx) = read_SSDR(reg);
        drv_data->rx += 2;
    }

    return drv_data->rx == drv_data->rx_end;
}

static int u32_writer(struct driver_data *drv_data)
{
    void __iomem *reg = drv_data->ioaddr;

    if (((read_SSSR(reg) & SSSR_TFL_MASK) == SSSR_TFL_MASK)
        || (drv_data->tx == drv_data->tx_end))
        return 0;

    write_SSDR(*(u32 *)(drv_data->tx), reg);
    drv_data->tx += 4;

    return 1;
}

static int u32_reader(struct driver_data *drv_data)
{
    void __iomem *reg = drv_data->ioaddr;

    while ((read_SSSR(reg) & SSSR_RNE)
        && (drv_data->rx < drv_data->rx_end)) {
        *(u32 *)(drv_data->rx) = read_SSDR(reg);
        drv_data->rx += 4;
    }

    return drv_data->rx == drv_data->rx_end;
}

static void *next_transfer(struct driver_data *drv_data)
{
    struct spi_message *msg = drv_data->cur_msg;
    struct spi_transfer *trans = drv_data->cur_transfer;

    /* Move to next transfer */
    if (trans->transfer_list.next != &msg->transfers) {
        drv_data->cur_transfer =
            list_entry(trans->transfer_list.next,
                    struct spi_transfer,
                    transfer_list);
        return RUNNING_STATE;
    } else
        return DONE_STATE;
}

static int map_dma_buffers(struct driver_data *drv_data)
{
    struct spi_message *msg = drv_data->cur_msg;
    struct device *dev = &msg->spi->dev;

    if (!drv_data->cur_chip->enable_dma)
        return 0;

    if (msg->is_dma_mapped)
        return  drv_data->rx_dma && drv_data->tx_dma;

    if (!IS_DMA_ALIGNED(drv_data->rx) || !IS_DMA_ALIGNED(drv_data->tx))
        return 0;

    /* Modify setup if rx buffer is null */
    if (drv_data->rx == NULL) {
        *drv_data->null_dma_buf = 0;
        drv_data->rx = drv_data->null_dma_buf;
        drv_data->rx_map_len = 4;
    } else
        drv_data->rx_map_len = drv_data->len;


    /* Modify setup if tx buffer is null */
    if (drv_data->tx == NULL) {
        *drv_data->null_dma_buf = 0;
        drv_data->tx = drv_data->null_dma_buf;
        drv_data->tx_map_len = 4;
    } else
        drv_data->tx_map_len = drv_data->len;

    /* Stream map the tx buffer. Always do DMA_TO_DEVICE first
     * so we flush the cache *before* invalidating it, in case
     * the tx and rx buffers overlap.
     */
    drv_data->tx_dma = dma_map_single(dev, drv_data->tx,
                    drv_data->tx_map_len, DMA_TO_DEVICE);
    if (dma_mapping_error(dev, drv_data->tx_dma))
        return 0;

    /* Stream map the rx buffer */
    drv_data->rx_dma = dma_map_single(dev, drv_data->rx,
                    drv_data->rx_map_len, DMA_FROM_DEVICE);
    if (dma_mapping_error(dev, drv_data->rx_dma)) {
        dma_unmap_single(dev, drv_data->tx_dma,
                    drv_data->tx_map_len, DMA_TO_DEVICE);
        return 0;
    }

    return 1;
}

static void unmap_dma_buffers(struct driver_data *drv_data)
{
    struct device *dev;

    if (!drv_data->dma_mapped)
        return;

    if (!drv_data->cur_msg->is_dma_mapped) {
        dev = &drv_data->cur_msg->spi->dev;
        dma_unmap_single(dev, drv_data->rx_dma,
                    drv_data->rx_map_len, DMA_FROM_DEVICE);
        dma_unmap_single(dev, drv_data->tx_dma,
                    drv_data->tx_map_len, DMA_TO_DEVICE);
    }

    drv_data->dma_mapped = 0;
}

/* caller already set message->status; dma and pio irqs are blocked */
static void giveback(struct driver_data *drv_data)
{
    struct spi_transfer* last_transfer;
    unsigned long flags;
    struct spi_message *msg;

    spin_lock_irqsave(&drv_data->lock, flags);
    msg = drv_data->cur_msg;
    drv_data->cur_msg = NULL;
    drv_data->cur_transfer = NULL;
    queue_work(drv_data->workqueue, &drv_data->pump_messages);
    spin_unlock_irqrestore(&drv_data->lock, flags);

    last_transfer = list_entry(msg->transfers.prev,
                    struct spi_transfer,
                    transfer_list);

    /* Delay if requested before any change in chip select */
    if (last_transfer->delay_usecs)
        udelay(last_transfer->delay_usecs);

    /* Drop chip select UNLESS cs_change is true or we are returning
     * a message with an error, or next message is for another chip
     */
    if (!last_transfer->cs_change)
        cs_deassert(drv_data);
    else {
        struct spi_message *next_msg;

        /* Holding of cs was hinted, but we need to make sure
         * the next message is for the same chip.  Don't waste
         * time with the following tests unless this was hinted.
         *
         * We cannot postpone this until pump_messages, because
         * after calling msg->complete (below) the driver that
         * sent the current message could be unloaded, which
         * could invalidate the cs_control() callback...
         */

        /* get a pointer to the next message, if any */
        spin_lock_irqsave(&drv_data->lock, flags);
        if (list_empty(&drv_data->queue))
            next_msg = NULL;
        else
            next_msg = list_entry(drv_data->queue.next,
                    struct spi_message, queue);
        spin_unlock_irqrestore(&drv_data->lock, flags);

        /* see if the next and current messages point
         * to the same chip
         */
        if (next_msg && next_msg->spi != msg->spi)
            next_msg = NULL;
        if (!next_msg || msg->state == ERROR_STATE)
            cs_deassert(drv_data);
    }

    msg->state = NULL;
    if (msg->complete)
        msg->complete(msg->context);

    drv_data->cur_chip = NULL;
}

static int wait_ssp_rx_stall(void const __iomem *ioaddr)
{
    unsigned long limit = loops_per_jiffy << 1;

    while ((read_SSSR(ioaddr) & SSSR_BSY) && --limit)
        cpu_relax();

    return limit;
}

static int wait_dma_channel_stop(int channel)
{
    unsigned long limit = loops_per_jiffy << 1;

    while (!(DCSR(channel) & DCSR_STOPSTATE) && --limit)
        cpu_relax();

    return limit;
}

static void dma_error_stop(struct driver_data *drv_data, const char *msg)
{
    void __iomem *reg = drv_data->ioaddr;

    /* Stop and reset */
    DCSR(drv_data->rx_channel) = RESET_DMA_CHANNEL;
    DCSR(drv_data->tx_channel) = RESET_DMA_CHANNEL;
    write_SSSR_CS(drv_data, drv_data->clear_sr);
    write_SSCR1(read_SSCR1(reg) & ~drv_data->dma_cr1, reg);
    if (!pxa25x_ssp_comp(drv_data))
        write_SSTO(0, reg);
    flush(drv_data);
    write_SSCR0(read_SSCR0(reg) & ~SSCR0_SSE, reg);

    unmap_dma_buffers(drv_data);

    dev_err(&drv_data->pdev->dev, "%s\n", msg);

    drv_data->cur_msg->state = ERROR_STATE;
    tasklet_schedule(&drv_data->pump_transfers);
}

static void dma_transfer_complete(struct driver_data *drv_data)
{
    void __iomem *reg = drv_data->ioaddr;
    struct spi_message *msg = drv_data->cur_msg;

    /* Clear and disable interrupts on SSP and DMA channels*/
    write_SSCR1(read_SSCR1(reg) & ~drv_data->dma_cr1, reg);
    write_SSSR_CS(drv_data, drv_data->clear_sr);
    DCSR(drv_data->tx_channel) = RESET_DMA_CHANNEL;
    DCSR(drv_data->rx_channel) = RESET_DMA_CHANNEL;

    if (wait_dma_channel_stop(drv_data->rx_channel) == 0)
        dev_err(&drv_data->pdev->dev,
            "dma_handler: dma rx channel stop failed\n");

    if (wait_ssp_rx_stall(drv_data->ioaddr) == 0)
        dev_err(&drv_data->pdev->dev,
            "dma_transfer: ssp rx stall failed\n");

    unmap_dma_buffers(drv_data);

    /* update the buffer pointer for the amount completed in dma */
    drv_data->rx += drv_data->len -
            (DCMD(drv_data->rx_channel) & DCMD_LENGTH);

    /* read trailing data from fifo, it does not matter how many
     * bytes are in the fifo just read until buffer is full
     * or fifo is empty, which ever occurs first */
    drv_data->read(drv_data);

    /* return count of what was actually read */
    msg->actual_length += drv_data->len -
                (drv_data->rx_end - drv_data->rx);

    /* Transfer delays and chip select release are
     * handled in pump_transfers or giveback
     */

    /* Move to next transfer */
    msg->state = next_transfer(drv_data);

    /* Schedule transfer tasklet */
    tasklet_schedule(&drv_data->pump_transfers);
}

static void dma_handler(int channel, void *data)
{
    struct driver_data *drv_data = data;
    u32 irq_status = DCSR(channel) & DMA_INT_MASK;

    if (irq_status & DCSR_BUSERR) {

        if (channel == drv_data->tx_channel)
            dma_error_stop(drv_data,
                    "dma_handler: "
                    "bad bus address on tx channel");
        else
            dma_error_stop(drv_data,
                    "dma_handler: "
                    "bad bus address on rx channel");
        return;
    }

    /* PXA255x_SSP has no timeout interrupt, wait for tailing bytes */
    if ((channel == drv_data->tx_channel)
        && (irq_status & DCSR_ENDINTR)
        && (drv_data->ssp_type == PXA25x_SSP)) {

        /* Wait for rx to stall */
        if (wait_ssp_rx_stall(drv_data->ioaddr) == 0)
            dev_err(&drv_data->pdev->dev,
                "dma_handler: ssp rx stall failed\n");

        /* finish this transfer, start the next */
        dma_transfer_complete(drv_data);
    }
}

static irqreturn_t dma_transfer(struct driver_data *drv_data)
{
    u32 irq_status;
    void __iomem *reg = drv_data->ioaddr;

    irq_status = read_SSSR(reg) & drv_data->mask_sr;
    if (irq_status & SSSR_ROR) {
        dma_error_stop(drv_data, "dma_transfer: fifo overrun");
        return IRQ_HANDLED;
    }

    /* Check for false positive timeout */
    if ((irq_status & SSSR_TINT)
        && (DCSR(drv_data->tx_channel) & DCSR_RUN)) {
        write_SSSR(SSSR_TINT, reg);
        return IRQ_HANDLED;
    }

    if (irq_status & SSSR_TINT || drv_data->rx == drv_data->rx_end) {

        /* Clear and disable timeout interrupt, do the rest in
         * dma_transfer_complete */
        if (!pxa25x_ssp_comp(drv_data))
            write_SSTO(0, reg);

        /* finish this transfer, start the next */
        dma_transfer_complete(drv_data);

        return IRQ_HANDLED;
    }

    /* Opps problem detected */
    return IRQ_NONE;
}

static void reset_sccr1(struct driver_data *drv_data)
{
    void __iomem *reg = drv_data->ioaddr;
    struct chip_data *chip = drv_data->cur_chip;
    u32 sccr1_reg;

    sccr1_reg = read_SSCR1(reg) & ~drv_data->int_cr1;
    sccr1_reg &= ~SSCR1_RFT;
    sccr1_reg |= chip->threshold;
    write_SSCR1(sccr1_reg, reg);
}

static void int_error_stop(struct driver_data *drv_data, const char* msg)
{
    void __iomem *reg = drv_data->ioaddr;

    /* Stop and reset SSP */
    write_SSSR_CS(drv_data, drv_data->clear_sr);
    reset_sccr1(drv_data);
    if (!pxa25x_ssp_comp(drv_data))
        write_SSTO(0, reg);
    flush(drv_data);
    write_SSCR0(read_SSCR0(reg) & ~SSCR0_SSE, reg);

    dev_err(&drv_data->pdev->dev, "%s\n", msg);

    drv_data->cur_msg->state = ERROR_STATE;
    tasklet_schedule(&drv_data->pump_transfers);
}

static void int_transfer_complete(struct driver_data *drv_data)
{
    void __iomem *reg = drv_data->ioaddr;

    /* Stop SSP */
    write_SSSR_CS(drv_data, drv_data->clear_sr);
    reset_sccr1(drv_data);
    if (!pxa25x_ssp_comp(drv_data))
        write_SSTO(0, reg);

    /* Update total byte transferred return count actual bytes read */
    drv_data->cur_msg->actual_length += drv_data->len -
                (drv_data->rx_end - drv_data->rx);

    /* Transfer delays and chip select release are
     * handled in pump_transfers or giveback
     */

    /* Move to next transfer */
    drv_data->cur_msg->state = next_transfer(drv_data);

    /* Schedule transfer tasklet */
    tasklet_schedule(&drv_data->pump_transfers);
}

static irqreturn_t interrupt_transfer(struct driver_data *drv_data)
{
    void __iomem *reg = drv_data->ioaddr;

    u32 irq_mask = (read_SSCR1(reg) & SSCR1_TIE) ?
            drv_data->mask_sr : drv_data->mask_sr & ~SSSR_TFS;

    u32 irq_status = read_SSSR(reg) & irq_mask;

    if (irq_status & SSSR_ROR) {
        int_error_stop(drv_data, "interrupt_transfer: fifo overrun");
        return IRQ_HANDLED;
    }

    if (irq_status & SSSR_TINT) {
        write_SSSR(SSSR_TINT, reg);
        if (drv_data->read(drv_data)) {
            int_transfer_complete(drv_data);
            return IRQ_HANDLED;
        }
    }

    /* Drain rx fifo, Fill tx fifo and prevent overruns */
    do {
        if (drv_data->read(drv_data)) {
            int_transfer_complete(drv_data);
            return IRQ_HANDLED;
        }
    } while (drv_data->write(drv_data));

    if (drv_data->read(drv_data)) {
        int_transfer_complete(drv_data);
        return IRQ_HANDLED;
    }

    if (drv_data->tx == drv_data->tx_end) {
        u32 bytes_left;
        u32 sccr1_reg;

        sccr1_reg = read_SSCR1(reg);
        sccr1_reg &= ~SSCR1_TIE;

        /*
         * PXA25x_SSP has no timeout, set up rx threshould for the
         * remaining RX bytes.
         */
        if (pxa25x_ssp_comp(drv_data)) {

            sccr1_reg &= ~SSCR1_RFT;

            bytes_left = drv_data->rx_end - drv_data->rx;
            switch (drv_data->n_bytes) {
            case 4:
                bytes_left >>= 1;
            case 2:
                bytes_left >>= 1;
            }

            if (bytes_left > RX_THRESH_DFLT)
                bytes_left = RX_THRESH_DFLT;

            sccr1_reg |= SSCR1_RxTresh(bytes_left);
        }
        write_SSCR1(sccr1_reg, reg);
    }

    /* We did something */
    return IRQ_HANDLED;
}

static irqreturn_t ssp_int(int irq, void *dev_id)
{
    struct driver_data *drv_data = dev_id;
    void __iomem *reg = drv_data->ioaddr;
    u32 sccr1_reg = read_SSCR1(reg);
    u32 mask = drv_data->mask_sr;
    u32 status;

    status = read_SSSR(reg);

    /* Ignore possible writes if we don't need to write */
    if (!(sccr1_reg & SSCR1_TIE))
        mask &= ~SSSR_TFS;

    if (!(status & mask))
        return IRQ_NONE;

    if (!drv_data->cur_msg) {

        write_SSCR0(read_SSCR0(reg) & ~SSCR0_SSE, reg);
        write_SSCR1(read_SSCR1(reg) & ~drv_data->int_cr1, reg);
        if (!pxa25x_ssp_comp(drv_data))
            write_SSTO(0, reg);
        write_SSSR_CS(drv_data, drv_data->clear_sr);

        dev_err(&drv_data->pdev->dev, "bad message state "
            "in interrupt handler\n");

        /* Never fail */
        return IRQ_HANDLED;
    }

    return drv_data->transfer_handler(drv_data);
}

static int set_dma_burst_and_threshold(struct chip_data *chip,
                struct spi_device *spi,
                u8 bits_per_word, u32 *burst_code,
                u32 *threshold)
{
    struct pxa2xx_spi_chip *chip_info =
            (struct pxa2xx_spi_chip *)spi->controller_data;
    int bytes_per_word;
    int burst_bytes;
    int thresh_words;
    int req_burst_size;
    int retval = 0;

    /* Set the threshold (in registers) to equal the same amount of data
     * as represented by burst size (in bytes).  The computation below
     * is (burst_size rounded up to nearest 8 byte, word or long word)
     * divided by (bytes/register); the tx threshold is the inverse of
     * the rx, so that there will always be enough data in the rx fifo
     * to satisfy a burst, and there will always be enough space in the
     * tx fifo to accept a burst (a tx burst will overwrite the fifo if
     * there is not enough space), there must always remain enough empty
     * space in the rx fifo for any data loaded to the tx fifo.
     * Whenever burst_size (in bytes) equals bits/word, the fifo threshold
     * will be 8, or half the fifo;
     * The threshold can only be set to 2, 4 or 8, but not 16, because
     * to burst 16 to the tx fifo, the fifo would have to be empty;
     * however, the minimum fifo trigger level is 1, and the tx will
     * request service when the fifo is at this level, with only 15 spaces.
     */

    /* find bytes/word */
    if (bits_per_word <= 8)
        bytes_per_word = 1;
    else if (bits_per_word <= 16)
        bytes_per_word = 2;
    else
        bytes_per_word = 4;

    /* use struct pxa2xx_spi_chip->dma_burst_size if available */
    if (chip_info)
        req_burst_size = chip_info->dma_burst_size;
    else {
        switch (chip->dma_burst_size) {
        default:
            /* if the default burst size is not set,
             * do it now */
            chip->dma_burst_size = DCMD_BURST8;
        case DCMD_BURST8:
            req_burst_size = 8;
            break;
        case DCMD_BURST16:
            req_burst_size = 16;
            break;
        case DCMD_BURST32:
            req_burst_size = 32;
            break;
        }
    }
    if (req_burst_size <= 8) {
        *burst_code = DCMD_BURST8;
        burst_bytes = 8;
    } else if (req_burst_size <= 16) {
        if (bytes_per_word == 1) {
            /* don't burst more than 1/2 the fifo */
            *burst_code = DCMD_BURST8;
            burst_bytes = 8;
            retval = 1;
        } else {
            *burst_code = DCMD_BURST16;
            burst_bytes = 16;
        }
    } else {
        if (bytes_per_word == 1) {
            /* don't burst more than 1/2 the fifo */
            *burst_code = DCMD_BURST8;
            burst_bytes = 8;
            retval = 1;
        } else if (bytes_per_word == 2) {
            /* don't burst more than 1/2 the fifo */
            *burst_code = DCMD_BURST16;
            burst_bytes = 16;
            retval = 1;
        } else {
            *burst_code = DCMD_BURST32;
            burst_bytes = 32;
        }
    }

    thresh_words = burst_bytes / bytes_per_word;

    /* thresh_words will be between 2 and 8 */
    *threshold = (SSCR1_RxTresh(thresh_words) & SSCR1_RFT)
            | (SSCR1_TxTresh(16-thresh_words) & SSCR1_TFT);

    return retval;
}

static unsigned int ssp_get_clk_div(struct ssp_device *ssp, int rate)
{
    unsigned long ssp_clk = clk_get_rate(ssp->clk);

    if (ssp->type == PXA25x_SSP || ssp->type == CE4100_SSP)
        return ((ssp_clk / (2 * rate) - 1) & 0xff) << 8;
    else
        return ((ssp_clk / rate - 1) & 0xfff) << 8;
}

static void pump_transfers(unsigned long data)
{
    struct driver_data *drv_data = (struct driver_data *)data;
    struct spi_message *message = NULL;
    struct spi_transfer *transfer = NULL;
    struct spi_transfer *previous = NULL;
    struct chip_data *chip = NULL;
    struct ssp_device *ssp = drv_data->ssp;
    void __iomem *reg = drv_data->ioaddr;
    u32 clk_div = 0;
    u8 bits = 0;
    u32 speed = 0;
    u32 cr0;
    u32 cr1;
    u32 dma_thresh = drv_data->cur_chip->dma_threshold;
    u32 dma_burst = drv_data->cur_chip->dma_burst_size;

    /* Get current state information */
    message = drv_data->cur_msg;
    transfer = drv_data->cur_transfer;
    chip = drv_data->cur_chip;

    /* Handle for abort */
    if (message->state == ERROR_STATE) {
        message->status = -EIO;
        giveback(drv_data);
        return;
    }

    /* Handle end of message */
    if (message->state == DONE_STATE) {
        message->status = 0;
        giveback(drv_data);
        return;
    }

    /* Delay if requested at end of transfer before CS change */
    if (message->state == RUNNING_STATE) {
        previous = list_entry(transfer->transfer_list.prev,
                    struct spi_transfer,
                    transfer_list);
        if (previous->delay_usecs)
            udelay(previous->delay_usecs);

        /* Drop chip select only if cs_change is requested */
        if (previous->cs_change)
            cs_deassert(drv_data);
    }

    /* Check for transfers that need multiple DMA segments */
    if (transfer->len > MAX_DMA_LEN && chip->enable_dma) {

        /* reject already-mapped transfers; PIO won't always work */
        if (message->is_dma_mapped
                || transfer->rx_dma || transfer->tx_dma) {
            dev_err(&drv_data->pdev->dev,
                "pump_transfers: mapped transfer length "
                "of %u is greater than %d\n",
                transfer->len, MAX_DMA_LEN);
            message->status = -EINVAL;
            giveback(drv_data);
            return;
        }

        /* warn ... we force this to PIO mode */
        if (printk_ratelimit())
            dev_warn(&message->spi->dev, "pump_transfers: "
                "DMA disabled for transfer length %ld "
                "greater than %d\n",
                (long)drv_data->len, MAX_DMA_LEN);
    }

    /* Setup the transfer state based on the type of transfer */
    if (flush(drv_data) == 0) {
        dev_err(&drv_data->pdev->dev, "pump_transfers: flush failed\n");
        message->status = -EIO;
        giveback(drv_data);
        return;
    }
    drv_data->n_bytes = chip->n_bytes;
    drv_data->dma_width = chip->dma_width;
    drv_data->tx = (void *)transfer->tx_buf;
    drv_data->tx_end = drv_data->tx + transfer->len;
    drv_data->rx = transfer->rx_buf;
    drv_data->rx_end = drv_data->rx + transfer->len;
    drv_data->rx_dma = transfer->rx_dma;
    drv_data->tx_dma = transfer->tx_dma;
    drv_data->len = transfer->len & DCMD_LENGTH;
    drv_data->write = drv_data->tx ? chip->write : null_writer;
    drv_data->read = drv_data->rx ? chip->read : null_reader;

    /* Change speed and bit per word on a per transfer */
    cr0 = chip->cr0;
    if (transfer->speed_hz || transfer->bits_per_word) {

        bits = chip->bits_per_word;
        speed = chip->speed_hz;

        if (transfer->speed_hz)
            speed = transfer->speed_hz;

        if (transfer->bits_per_word)
            bits = transfer->bits_per_word;

        clk_div = ssp_get_clk_div(ssp, speed);

        if (bits <= 8) {
            drv_data->n_bytes = 1;
            drv_data->dma_width = DCMD_WIDTH1;
            drv_data->read = drv_data->read != null_reader ?
                        u8_reader : null_reader;
            drv_data->write = drv_data->write != null_writer ?
                        u8_writer : null_writer;
        } else if (bits <= 16) {
            drv_data->n_bytes = 2;
            drv_data->dma_width = DCMD_WIDTH2;
            drv_data->read = drv_data->read != null_reader ?
                        u16_reader : null_reader;
            drv_data->write = drv_data->write != null_writer ?
                        u16_writer : null_writer;
        } else if (bits <= 32) {
            drv_data->n_bytes = 4;
            drv_data->dma_width = DCMD_WIDTH4;
            drv_data->read = drv_data->read != null_reader ?
                        u32_reader : null_reader;
            drv_data->write = drv_data->write != null_writer ?
                        u32_writer : null_writer;
        }
        /* if bits/word is changed in dma mode, then must check the
         * thresholds and burst also */
        if (chip->enable_dma) {
            if (set_dma_burst_and_threshold(chip, message->spi,
                            bits, &dma_burst,
                            &dma_thresh))
                if (printk_ratelimit())
                    dev_warn(&message->spi->dev,
                        "pump_transfers: "
                        "DMA burst size reduced to "
                        "match bits_per_word\n");
        }

        cr0 = clk_div
            | SSCR0_Motorola
            | SSCR0_DataSize(bits > 16 ? bits - 16 : bits)
            | SSCR0_SSE
            | (bits > 16 ? SSCR0_EDSS : 0);
    }

    message->state = RUNNING_STATE;

    /* Try to map dma buffer and do a dma transfer if successful, but
     * only if the length is non-zero and less than MAX_DMA_LEN.
     *
     * Zero-length non-descriptor DMA is illegal on PXA2xx; force use
     * of PIO instead.  Care is needed above because the transfer may
     * have have been passed with buffers that are already dma mapped.
     * A zero-length transfer in PIO mode will not try to write/read
     * to/from the buffers
     *
     * REVISIT large transfers are exactly where we most want to be
     * using DMA.  If this happens much, split those transfers into
     * multiple DMA segments rather than forcing PIO.
     */
    drv_data->dma_mapped = 0;
    if (drv_data->len > 0 && drv_data->len <= MAX_DMA_LEN)
        drv_data->dma_mapped = map_dma_buffers(drv_data);
    if (drv_data->dma_mapped) {

        /* Ensure we have the correct interrupt handler */
        drv_data->transfer_handler = dma_transfer;

        /* Setup rx DMA Channel */
        DCSR(drv_data->rx_channel) = RESET_DMA_CHANNEL;
        DSADR(drv_data->rx_channel) = drv_data->ssdr_physical;
        DTADR(drv_data->rx_channel) = drv_data->rx_dma;
        if (drv_data->rx == drv_data->null_dma_buf)
            /* No target address increment */
            DCMD(drv_data->rx_channel) = DCMD_FLOWSRC
                            | drv_data->dma_width
                            | dma_burst
                            | drv_data->len;
        else
            DCMD(drv_data->rx_channel) = DCMD_INCTRGADDR
                            | DCMD_FLOWSRC
                            | drv_data->dma_width
                            | dma_burst
                            | drv_data->len;

        /* Setup tx DMA Channel */
        DCSR(drv_data->tx_channel) = RESET_DMA_CHANNEL;
        DSADR(drv_data->tx_channel) = drv_data->tx_dma;
        DTADR(drv_data->tx_channel) = drv_data->ssdr_physical;
        if (drv_data->tx == drv_data->null_dma_buf)
            /* No source address increment */
            DCMD(drv_data->tx_channel) = DCMD_FLOWTRG
                            | drv_data->dma_width
                            | dma_burst
                            | drv_data->len;
        else
            DCMD(drv_data->tx_channel) = DCMD_INCSRCADDR
                            | DCMD_FLOWTRG
                            | drv_data->dma_width
                            | dma_burst
                            | drv_data->len;

        /* Enable dma end irqs on SSP to detect end of transfer */
        if (drv_data->ssp_type == PXA25x_SSP)
            DCMD(drv_data->tx_channel) |= DCMD_ENDIRQEN;

        /* Clear status and start DMA engine */
        cr1 = chip->cr1 | dma_thresh | drv_data->dma_cr1;
        write_SSSR(drv_data->clear_sr, reg);
        DCSR(drv_data->rx_channel) |= DCSR_RUN;
        DCSR(drv_data->tx_channel) |= DCSR_RUN;
    } else {
        /* Ensure we have the correct interrupt handler */
        drv_data->transfer_handler = interrupt_transfer;

        /* Clear status  */
        cr1 = chip->cr1 | chip->threshold | drv_data->int_cr1;
        write_SSSR_CS(drv_data, drv_data->clear_sr);
    }

    /* see if we need to reload the config registers */
    if ((read_SSCR0(reg) != cr0)
        || (read_SSCR1(reg) & SSCR1_CHANGE_MASK) !=
            (cr1 & SSCR1_CHANGE_MASK)) {

        /* stop the SSP, and update the other bits */
        write_SSCR0(cr0 & ~SSCR0_SSE, reg);
        if (!pxa25x_ssp_comp(drv_data))
            write_SSTO(chip->timeout, reg);
        /* first set CR1 without interrupt and service enables */
        write_SSCR1(cr1 & SSCR1_CHANGE_MASK, reg);
        /* restart the SSP */
        write_SSCR0(cr0, reg);

    } else {
        if (!pxa25x_ssp_comp(drv_data))
            write_SSTO(chip->timeout, reg);
    }

    cs_assert(drv_data);

    /* after chip select, release the data by enabling service
     * requests and interrupts, without changing any mode bits */
    write_SSCR1(cr1, reg);
}

static void pump_messages(struct work_struct *work)
{
    struct driver_data *drv_data =
        container_of(work, struct driver_data, pump_messages);
    unsigned long flags;

    /* Lock queue and check for queue work */
    spin_lock_irqsave(&drv_data->lock, flags);
    if (list_empty(&drv_data->queue) || drv_data->run == QUEUE_STOPPED) {
        drv_data->busy = 0;
        spin_unlock_irqrestore(&drv_data->lock, flags);
        return;
    }

    /* Make sure we are not already running a message */
    if (drv_data->cur_msg) {
        spin_unlock_irqrestore(&drv_data->lock, flags);
        return;
    }

    /* Extract head of queue */
    drv_data->cur_msg = list_entry(drv_data->queue.next,
                    struct spi_message, queue);
    list_del_init(&drv_data->cur_msg->queue);

    /* Initial message state*/
    drv_data->cur_msg->state = START_STATE;
    drv_data->cur_transfer = list_entry(drv_data->cur_msg->transfers.next,
                        struct spi_transfer,
                        transfer_list);

    /* prepare to setup the SSP, in pump_transfers, using the per
     * chip configuration */
    drv_data->cur_chip = spi_get_ctldata(drv_data->cur_msg->spi);

    /* Mark as busy and launch transfers */
    tasklet_schedule(&drv_data->pump_transfers);

    drv_data->busy = 1;
    spin_unlock_irqrestore(&drv_data->lock, flags);
}

static int transfer(struct spi_device *spi, struct spi_message *msg)
{
    struct driver_data *drv_data = spi_master_get_devdata(spi->master);
    unsigned long flags;

    spin_lock_irqsave(&drv_data->lock, flags);

    if (drv_data->run == QUEUE_STOPPED) {
        spin_unlock_irqrestore(&drv_data->lock, flags);
        return -ESHUTDOWN;
    }

    msg->actual_length = 0;
    msg->status = -EINPROGRESS;
    msg->state = START_STATE;

    list_add_tail(&msg->queue, &drv_data->queue);

    if (drv_data->run == QUEUE_RUNNING && !drv_data->busy)
        queue_work(drv_data->workqueue, &drv_data->pump_messages);

    spin_unlock_irqrestore(&drv_data->lock, flags);

    return 0;
}

static int setup_cs(struct spi_device *spi, struct chip_data *chip,
            struct pxa2xx_spi_chip *chip_info)
{
    int err = 0;

    if (chip == NULL || chip_info == NULL)
        return 0;

    /* NOTE: setup() can be called multiple times, possibly with
     * different chip_info, release previously requested GPIO
     */
    if (gpio_is_valid(chip->gpio_cs))
        gpio_free(chip->gpio_cs);

    /* If (*cs_control) is provided, ignore GPIO chip select */
    if (chip_info->cs_control) {
        chip->cs_control = chip_info->cs_control;
        return 0;
    }

    if (gpio_is_valid(chip_info->gpio_cs)) {
        err = gpio_request(chip_info->gpio_cs, "SPI_CS");
        if (err) {
            dev_err(&spi->dev, "failed to request chip select "
                    "GPIO%d\n", chip_info->gpio_cs);
            return err;
        }

        chip->gpio_cs = chip_info->gpio_cs;
        chip->gpio_cs_inverted = spi->mode & SPI_CS_HIGH;

        err = gpio_direction_output(chip->gpio_cs,
                    !chip->gpio_cs_inverted);
    }

    return err;
}

static int setup(struct spi_device *spi)
{
    struct pxa2xx_spi_chip *chip_info = NULL;
    struct chip_data *chip;
    struct driver_data *drv_data = spi_master_get_devdata(spi->master);
    struct ssp_device *ssp = drv_data->ssp;
    unsigned int clk_div;
    uint tx_thres = TX_THRESH_DFLT;
    uint rx_thres = RX_THRESH_DFLT;

    if (!pxa25x_ssp_comp(drv_data)
        && (spi->bits_per_word < 4 || spi->bits_per_word > 32)) {
        dev_err(&spi->dev, "failed setup: ssp_type=%d, bits/wrd=%d "
                "b/w not 4-32 for type non-PXA25x_SSP\n",
                drv_data->ssp_type, spi->bits_per_word);
        return -EINVAL;
    } else if (pxa25x_ssp_comp(drv_data)
            && (spi->bits_per_word < 4
                || spi->bits_per_word > 16)) {
        dev_err(&spi->dev, "failed setup: ssp_type=%d, bits/wrd=%d "
                "b/w not 4-16 for type PXA25x_SSP\n",
                drv_data->ssp_type, spi->bits_per_word);
        return -EINVAL;
    }

    /* Only alloc on first setup */
    chip = spi_get_ctldata(spi);
    if (!chip) {
        chip = kzalloc(sizeof(struct chip_data), GFP_KERNEL);
        if (!chip) {
            dev_err(&spi->dev,
                "failed setup: can't allocate chip data\n");
            return -ENOMEM;
        }

        if (drv_data->ssp_type == CE4100_SSP) {
            if (spi->chip_select > 4) {
                dev_err(&spi->dev, "failed setup: "
                "cs number must not be > 4.\n");
                kfree(chip);
                return -EINVAL;
            }

            chip->frm = spi->chip_select;
        } else
            chip->gpio_cs = -1;
        chip->enable_dma = 0;
        chip->timeout = TIMOUT_DFLT;
        chip->dma_burst_size = drv_data->master_info->enable_dma ?
                    DCMD_BURST8 : 0;
    }

    /* protocol drivers may change the chip settings, so...
     * if chip_info exists, use it */
    chip_info = spi->controller_data;

    /* chip_info isn't always needed */
    chip->cr1 = 0;
    if (chip_info) {
        if (chip_info->timeout)
            chip->timeout = chip_info->timeout;
        if (chip_info->tx_threshold)
            tx_thres = chip_info->tx_threshold;
        if (chip_info->rx_threshold)
            rx_thres = chip_info->rx_threshold;
        chip->enable_dma = drv_data->master_info->enable_dma;
        chip->dma_threshold = 0;
        if (chip_info->enable_loopback)
            chip->cr1 = SSCR1_LBM;
    }

    chip->threshold = (SSCR1_RxTresh(rx_thres) & SSCR1_RFT) |
            (SSCR1_TxTresh(tx_thres) & SSCR1_TFT);

    /* set dma burst and threshold outside of chip_info path so that if
     * chip_info goes away after setting chip->enable_dma, the
     * burst and threshold can still respond to changes in bits_per_word */
    if (chip->enable_dma) {
        /* set up legal burst and threshold for dma */
        if (set_dma_burst_and_threshold(chip, spi, spi->bits_per_word,
                        &chip->dma_burst_size,
                        &chip->dma_threshold)) {
            dev_warn(&spi->dev, "in setup: DMA burst size reduced "
                    "to match bits_per_word\n");
        }
    }

    clk_div = ssp_get_clk_div(ssp, spi->max_speed_hz);
    chip->speed_hz = spi->max_speed_hz;

    chip->cr0 = clk_div
            | SSCR0_Motorola
            | SSCR0_DataSize(spi->bits_per_word > 16 ?
                spi->bits_per_word - 16 : spi->bits_per_word)
            | SSCR0_SSE
            | (spi->bits_per_word > 16 ? SSCR0_EDSS : 0);
    chip->cr1 &= ~(SSCR1_SPO | SSCR1_SPH);
    chip->cr1 |= (((spi->mode & SPI_CPHA) != 0) ? SSCR1_SPH : 0)
            | (((spi->mode & SPI_CPOL) != 0) ? SSCR1_SPO : 0);

    /* NOTE:  PXA25x_SSP _could_ use external clocking ... */
    if (!pxa25x_ssp_comp(drv_data))
        dev_dbg(&spi->dev, "%ld Hz actual, %s\n",
            clk_get_rate(ssp->clk)
                / (1 + ((chip->cr0 & SSCR0_SCR(0xfff)) >> 8)),
            chip->enable_dma ? "DMA" : "PIO");
    else
        dev_dbg(&spi->dev, "%ld Hz actual, %s\n",
            clk_get_rate(ssp->clk) / 2
                / (1 + ((chip->cr0 & SSCR0_SCR(0x0ff)) >> 8)),
            chip->enable_dma ? "DMA" : "PIO");

    if (spi->bits_per_word <= 8) {
        chip->n_bytes = 1;
        chip->dma_width = DCMD_WIDTH1;
        chip->read = u8_reader;
        chip->write = u8_writer;
    } else if (spi->bits_per_word <= 16) {
        chip->n_bytes = 2;
        chip->dma_width = DCMD_WIDTH2;
        chip->read = u16_reader;
        chip->write = u16_writer;
    } else if (spi->bits_per_word <= 32) {
        chip->cr0 |= SSCR0_EDSS;
        chip->n_bytes = 4;
        chip->dma_width = DCMD_WIDTH4;
        chip->read = u32_reader;
        chip->write = u32_writer;
    } else {
        dev_err(&spi->dev, "invalid wordsize\n");
        return -ENODEV;
    }
    chip->bits_per_word = spi->bits_per_word;

    spi_set_ctldata(spi, chip);

    if (drv_data->ssp_type == CE4100_SSP)
        return 0;

    return setup_cs(spi, chip, chip_info);
}

static void cleanup(struct spi_device *spi)
{
    struct chip_data *chip = spi_get_ctldata(spi);
    struct driver_data *drv_data = spi_master_get_devdata(spi->master);

    if (!chip)
        return;

    if (drv_data->ssp_type != CE4100_SSP && gpio_is_valid(chip->gpio_cs))
        gpio_free(chip->gpio_cs);

    kfree(chip);
}

static int __devinit init_queue(struct driver_data *drv_data)
{
    INIT_LIST_HEAD(&drv_data->queue);
    spin_lock_init(&drv_data->lock);

    drv_data->run = QUEUE_STOPPED;
    drv_data->busy = 0;

    tasklet_init(&drv_data->pump_transfers,
            pump_transfers, (unsigned long)drv_data);

    INIT_WORK(&drv_data->pump_messages, pump_messages);
    drv_data->workqueue = create_singlethread_workqueue(
                dev_name(drv_data->master->dev.parent));
    if (drv_data->workqueue == NULL)
        return -EBUSY;

    return 0;
}

static int start_queue(struct driver_data *drv_data)
{
    unsigned long flags;

    spin_lock_irqsave(&drv_data->lock, flags);

    if (drv_data->run == QUEUE_RUNNING || drv_data->busy) {
        spin_unlock_irqrestore(&drv_data->lock, flags);
        return -EBUSY;
    }

    drv_data->run = QUEUE_RUNNING;
    drv_data->cur_msg = NULL;
    drv_data->cur_transfer = NULL;
    drv_data->cur_chip = NULL;
    spin_unlock_irqrestore(&drv_data->lock, flags);

    queue_work(drv_data->workqueue, &drv_data->pump_messages);

    return 0;
}

static int stop_queue(struct driver_data *drv_data)
{
    unsigned long flags;
    unsigned limit = 500;
    int status = 0;

    spin_lock_irqsave(&drv_data->lock, flags);

    /* This is a bit lame, but is optimized for the common execution path.
     * A wait_queue on the drv_data->busy could be used, but then the common
     * execution path (pump_messages) would be required to call wake_up or
     * friends on every SPI message. Do this instead */
    drv_data->run = QUEUE_STOPPED;
    while ((!list_empty(&drv_data->queue) || drv_data->busy) && limit--) {
        spin_unlock_irqrestore(&drv_data->lock, flags);
        msleep(10);
        spin_lock_irqsave(&drv_data->lock, flags);
    }

    if (!list_empty(&drv_data->queue) || drv_data->busy)
        status = -EBUSY;

    spin_unlock_irqrestore(&drv_data->lock, flags);

    return status;
}

static int destroy_queue(struct driver_data *drv_data)
{
    int status;

    status = stop_queue(drv_data);
    /* we are unloading the module or failing to load (only two calls
     * to this routine), and neither call can handle a return value.
     * However, destroy_workqueue calls flush_workqueue, and that will
     * block until all work is done.  If the reason that stop_queue
     * timed out is that the work will never finish, then it does no
     * good to call destroy_workqueue, so return anyway. */
    if (status != 0)
        return status;

    destroy_workqueue(drv_data->workqueue);

    return 0;
}

static int __devinit pxa2xx_spi_probe(struct platform_device *pdev)
{
    struct device *dev = &pdev->dev;
    struct pxa2xx_spi_master *platform_info;
    struct spi_master *master;
    struct driver_data *drv_data;
    struct ssp_device *ssp;
    int status;

    platform_info = dev->platform_data;

    ssp = pxa_ssp_request(pdev->id, pdev->name);
    if (ssp == NULL) {
        dev_err(&pdev->dev, "failed to request SSP%d\n", pdev->id);
        return -ENODEV;
    }

    /* Allocate master with space for drv_data and null dma buffer */
    master = spi_alloc_master(dev, sizeof(struct driver_data) + 16);
    if (!master) {
        dev_err(&pdev->dev, "cannot alloc spi_master\n");
        pxa_ssp_free(ssp);
        return -ENOMEM;
    }
    drv_data = spi_master_get_devdata(master);
    drv_data->master = master;
    drv_data->master_info = platform_info;
    drv_data->pdev = pdev;
    drv_data->ssp = ssp;

    master->dev.parent = &pdev->dev;
    master->dev.of_node = pdev->dev.of_node;
    /* the spi->mode bits understood by this driver: */
    master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;

    master->bus_num = pdev->id;
    master->num_chipselect = platform_info->num_chipselect;
    master->dma_alignment = DMA_ALIGNMENT;
    master->cleanup = cleanup;
    master->setup = setup;
    master->transfer = transfer;

    drv_data->ssp_type = ssp->type;
    drv_data->null_dma_buf = (u32 *)ALIGN((u32)(drv_data +
                        sizeof(struct driver_data)), 8);

    drv_data->ioaddr = ssp->mmio_base;
    drv_data->ssdr_physical = ssp->phys_base + SSDR;
    if (pxa25x_ssp_comp(drv_data)) {
        drv_data->int_cr1 = SSCR1_TIE | SSCR1_RIE;
        drv_data->dma_cr1 = 0;
        drv_data->clear_sr = SSSR_ROR;
        drv_data->mask_sr = SSSR_RFS | SSSR_TFS | SSSR_ROR;
    } else {
        drv_data->int_cr1 = SSCR1_TIE | SSCR1_RIE | SSCR1_TINTE;
        drv_data->dma_cr1 = SSCR1_TSRE | SSCR1_RSRE | SSCR1_TINTE;
        drv_data->clear_sr = SSSR_ROR | SSSR_TINT;
        drv_data->mask_sr = SSSR_TINT | SSSR_RFS | SSSR_TFS | SSSR_ROR;
    }

    status = request_irq(ssp->irq, ssp_int, IRQF_SHARED, dev_name(dev),
            drv_data);
    if (status < 0) {
        dev_err(&pdev->dev, "cannot get IRQ %d\n", ssp->irq);
        goto out_error_master_alloc;
    }

    /* Setup DMA if requested */
    drv_data->tx_channel = -1;
    drv_data->rx_channel = -1;
    if (platform_info->enable_dma) {

        /* Get two DMA channels (rx and tx) */
        drv_data->rx_channel = pxa_request_dma("pxa2xx_spi_ssp_rx",
                            DMA_PRIO_HIGH,
                            dma_handler,
                            drv_data);
        if (drv_data->rx_channel < 0) {
            dev_err(dev, "problem (%d) requesting rx channel\n",
                drv_data->rx_channel);
            status = -ENODEV;
            goto out_error_irq_alloc;
        }
        drv_data->tx_channel = pxa_request_dma("pxa2xx_spi_ssp_tx",
                            DMA_PRIO_MEDIUM,
                            dma_handler,
                            drv_data);
        if (drv_data->tx_channel < 0) {
            dev_err(dev, "problem (%d) requesting tx channel\n",
                drv_data->tx_channel);
            status = -ENODEV;
            goto out_error_dma_alloc;
        }

        DRCMR(ssp->drcmr_rx) = DRCMR_MAPVLD | drv_data->rx_channel;
        DRCMR(ssp->drcmr_tx) = DRCMR_MAPVLD | drv_data->tx_channel;
    }

    /* Enable SOC clock */
    clk_enable(ssp->clk);

    /* Load default SSP configuration */
    write_SSCR0(0, drv_data->ioaddr);
    write_SSCR1(SSCR1_RxTresh(RX_THRESH_DFLT) |
                SSCR1_TxTresh(TX_THRESH_DFLT),
                drv_data->ioaddr);
    write_SSCR0(SSCR0_SCR(2)
            | SSCR0_Motorola
            | SSCR0_DataSize(8),
            drv_data->ioaddr);
    if (!pxa25x_ssp_comp(drv_data))
        write_SSTO(0, drv_data->ioaddr);
    write_SSPSP(0, drv_data->ioaddr);

    /* Initial and start queue */
    status = init_queue(drv_data);
    if (status != 0) {
        dev_err(&pdev->dev, "problem initializing queue\n");
        goto out_error_clock_enabled;
    }
    status = start_queue(drv_data);
    if (status != 0) {
        dev_err(&pdev->dev, "problem starting queue\n");
        goto out_error_clock_enabled;
    }

    /* Register with the SPI framework */
    platform_set_drvdata(pdev, drv_data);
    status = spi_register_master(master);
    if (status != 0) {
        dev_err(&pdev->dev, "problem registering spi master\n");
        goto out_error_queue_alloc;
    }

    return status;

out_error_queue_alloc:
    destroy_queue(drv_data);

out_error_clock_enabled:
    clk_disable(ssp->clk);

out_error_dma_alloc:
    if (drv_data->tx_channel != -1)
        pxa_free_dma(drv_data->tx_channel);
    if (drv_data->rx_channel != -1)
        pxa_free_dma(drv_data->rx_channel);

out_error_irq_alloc:
    free_irq(ssp->irq, drv_data);

out_error_master_alloc:
    spi_master_put(master);
    pxa_ssp_free(ssp);
    return status;
}

static int pxa2xx_spi_remove(struct platform_device *pdev)
{
    struct driver_data *drv_data = platform_get_drvdata(pdev);
    struct ssp_device *ssp;
    int status = 0;

    if (!drv_data)
        return 0;
    ssp = drv_data->ssp;

    /* Remove the queue */
    status = destroy_queue(drv_data);
    if (status != 0)
        /* the kernel does not check the return status of this
         * this routine (mod->exit, within the kernel).  Therefore
         * nothing is gained by returning from here, the module is
         * going away regardless, and we should not leave any more
         * resources allocated than necessary.  We cannot free the
         * message memory in drv_data->queue, but we can release the
         * resources below.  I think the kernel should honor -EBUSY
         * returns but... */
        dev_err(&pdev->dev, "pxa2xx_spi_remove: workqueue will not "
            "complete, message memory not freed\n");

    /* Disable the SSP at the peripheral and SOC level */
    write_SSCR0(0, drv_data->ioaddr);
    clk_disable(ssp->clk);

    /* Release DMA */
    if (drv_data->master_info->enable_dma) {
        DRCMR(ssp->drcmr_rx) = 0;
        DRCMR(ssp->drcmr_tx) = 0;
        pxa_free_dma(drv_data->tx_channel);
        pxa_free_dma(drv_data->rx_channel);
    }

    /* Release IRQ */
    free_irq(ssp->irq, drv_data);

    /* Release SSP */
    pxa_ssp_free(ssp);

    /* Disconnect from the SPI framework */
    spi_unregister_master(drv_data->master);

    /* Prevent double remove */
    platform_set_drvdata(pdev, NULL);

    return 0;
}

static void pxa2xx_spi_shutdown(struct platform_device *pdev)
{
    int status = 0;

    if ((status = pxa2xx_spi_remove(pdev)) != 0)
        dev_err(&pdev->dev, "shutdown failed with %d\n", status);
}

#ifdef CONFIG_PM
static int pxa2xx_spi_suspend(struct device *dev)
{
    struct driver_data *drv_data = dev_get_drvdata(dev);
    struct ssp_device *ssp = drv_data->ssp;
    int status = 0;

    status = stop_queue(drv_data);
    if (status != 0)
        return status;
    write_SSCR0(0, drv_data->ioaddr);
    clk_disable(ssp->clk);

    return 0;
}

static int pxa2xx_spi_resume(struct device *dev)
{
    struct driver_data *drv_data = dev_get_drvdata(dev);
    struct ssp_device *ssp = drv_data->ssp;
    int status = 0;

    if (drv_data->rx_channel != -1)
        DRCMR(drv_data->ssp->drcmr_rx) =
            DRCMR_MAPVLD | drv_data->rx_channel;
    if (drv_data->tx_channel != -1)
        DRCMR(drv_data->ssp->drcmr_tx) =
            DRCMR_MAPVLD | drv_data->tx_channel;

    /* Enable the SSP clock */
    clk_enable(ssp->clk);

    /* Start the queue running */
    status = start_queue(drv_data);
    if (status != 0) {
        dev_err(dev, "problem starting queue (%d)\n", status);
        return status;
    }

    return 0;
}

static const struct dev_pm_ops pxa2xx_spi_pm_ops = {
    .suspend    = pxa2xx_spi_suspend,
    .resume     = pxa2xx_spi_resume,
};
#endif

static struct platform_driver driver = {
    .driver = {
        .name   = "pxa2xx-spi",
        .owner  = THIS_MODULE,
#ifdef CONFIG_PM
        .pm = &pxa2xx_spi_pm_ops,
#endif
    },
    .probe = pxa2xx_spi_probe,
    .remove = pxa2xx_spi_remove,
    .shutdown = pxa2xx_spi_shutdown,
};

static int __init pxa2xx_spi_init(void)
{
    return platform_driver_register(&driver);
}
subsys_initcall(pxa2xx_spi_init);

static void __exit pxa2xx_spi_exit(void)
{
    platform_driver_unregister(&driver);
}
module_exit(pxa2xx_spi_exit);