/*
 * Designware SPI core controller driver (refer pxa2xx_spi.c)
 *
 * Copyright (c) 2009, Intel Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope 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.,
 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include <linux/dma-mapping.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/highmem.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/spi/spi.h>

#include "spi-dw.h"

#ifdef CONFIG_DEBUG_FS
#include <linux/debugfs.h>
#endif

#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

#define MRST_SPI_DEASSERT       0
#define MRST_SPI_ASSERT         1

/* Slave spi_dev related */
struct chip_data {
        u16 cr0;
        u8 cs;                  /* chip select pin */
        u8 n_bytes;             /* current is a 1/2/4 byte op */
        u8 tmode;               /* TR/TO/RO/EEPROM */
        u8 type;                /* SPI/SSP/MicroWire */

        u8 poll_mode;           /* 1 means use poll mode */

        u32 dma_width;
        u32 rx_threshold;
        u32 tx_threshold;
        u8 enable_dma;
        u8 bits_per_word;
        u16 clk_div;            /* baud rate divider */
        u32 speed_hz;           /* baud rate */
        void (*cs_control)(u32 command);
};

#ifdef CONFIG_DEBUG_FS
#define SPI_REGS_BUFSIZE        1024
static ssize_t  spi_show_regs(struct file *file, char __user *user_buf,
                                size_t count, loff_t *ppos)
{
        struct dw_spi *dws;
        char *buf;
        u32 len = 0;
        ssize_t ret;

        dws = file->private_data;

        buf = kzalloc(SPI_REGS_BUFSIZE, GFP_KERNEL);
        if (!buf)
                return 0;

        len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
                        "MRST SPI0 registers:\n");
        len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
                        "=================================\n");
        len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
                        "CTRL0: \t\t0x%08x\n", dw_readl(dws, DW_SPI_CTRL0));
        len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
                        "CTRL1: \t\t0x%08x\n", dw_readl(dws, DW_SPI_CTRL1));
        len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
                        "SSIENR: \t0x%08x\n", dw_readl(dws, DW_SPI_SSIENR));
        len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
                        "SER: \t\t0x%08x\n", dw_readl(dws, DW_SPI_SER));
        len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
                        "BAUDR: \t\t0x%08x\n", dw_readl(dws, DW_SPI_BAUDR));
        len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
                        "TXFTLR: \t0x%08x\n", dw_readl(dws, DW_SPI_TXFLTR));
        len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
                        "RXFTLR: \t0x%08x\n", dw_readl(dws, DW_SPI_RXFLTR));
        len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
                        "TXFLR: \t\t0x%08x\n", dw_readl(dws, DW_SPI_TXFLR));
        len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
                        "RXFLR: \t\t0x%08x\n", dw_readl(dws, DW_SPI_RXFLR));
        len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
                        "SR: \t\t0x%08x\n", dw_readl(dws, DW_SPI_SR));
        len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
                        "IMR: \t\t0x%08x\n", dw_readl(dws, DW_SPI_IMR));
        len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
                        "ISR: \t\t0x%08x\n", dw_readl(dws, DW_SPI_ISR));
        len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
                        "DMACR: \t\t0x%08x\n", dw_readl(dws, DW_SPI_DMACR));
        len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
                        "DMATDLR: \t0x%08x\n", dw_readl(dws, DW_SPI_DMATDLR));
        len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
                        "DMARDLR: \t0x%08x\n", dw_readl(dws, DW_SPI_DMARDLR));
        len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
                        "=================================\n");

        ret =  simple_read_from_buffer(user_buf, count, ppos, buf, len);
        kfree(buf);
        return ret;
}

static const struct file_operations mrst_spi_regs_ops = {
        .owner          = THIS_MODULE,
        .open           = simple_open,
        .read           = spi_show_regs,
        .llseek         = default_llseek,
};

static int mrst_spi_debugfs_init(struct dw_spi *dws)
{
        dws->debugfs = debugfs_create_dir("mrst_spi", NULL);
        if (!dws->debugfs)
                return -ENOMEM;

        debugfs_create_file("registers", S_IFREG | S_IRUGO,
                dws->debugfs, (void *)dws, &mrst_spi_regs_ops);
        return 0;
}

static void mrst_spi_debugfs_remove(struct dw_spi *dws)
{
        if (dws->debugfs)
                debugfs_remove_recursive(dws->debugfs);
}

#else
static inline int mrst_spi_debugfs_init(struct dw_spi *dws)
{
        return 0;
}

static inline void mrst_spi_debugfs_remove(struct dw_spi *dws)
{
}
#endif /* CONFIG_DEBUG_FS */

/* Return the max entries we can fill into tx fifo */
static inline u32 tx_max(struct dw_spi *dws)
{
        u32 tx_left, tx_room, rxtx_gap;

        tx_left = (dws->tx_end - dws->tx) / dws->n_bytes;
        tx_room = dws->fifo_len - dw_readw(dws, DW_SPI_TXFLR);

        /*
         * Another concern is about the tx/rx mismatch, we
         * though to use (dws->fifo_len - rxflr - txflr) as
         * one maximum value for tx, but it doesn't cover the
         * data which is out of tx/rx fifo and inside the
         * shift registers. So a control from sw point of
         * view is taken.
         */
        rxtx_gap =  ((dws->rx_end - dws->rx) - (dws->tx_end - dws->tx))
                        / dws->n_bytes;

        return min3(tx_left, tx_room, (u32) (dws->fifo_len - rxtx_gap));
}

/* Return the max entries we should read out of rx fifo */
static inline u32 rx_max(struct dw_spi *dws)
{
        u32 rx_left = (dws->rx_end - dws->rx) / dws->n_bytes;

        return min(rx_left, (u32)dw_readw(dws, DW_SPI_RXFLR));
}

static void dw_writer(struct dw_spi *dws)
{
        u32 max = tx_max(dws);
        u16 txw = 0;

        while (max--) {
                /* Set the tx word if the transfer's original "tx" is not null */
                if (dws->tx_end - dws->len) {
                        if (dws->n_bytes == 1)
                                txw = *(u8 *)(dws->tx);
                        else
                                txw = *(u16 *)(dws->tx);
                }
                dw_writew(dws, DW_SPI_DR, txw);
                dws->tx += dws->n_bytes;
        }
}

static void dw_reader(struct dw_spi *dws)
{
        u32 max = rx_max(dws);
        u16 rxw;

        while (max--) {
                rxw = dw_readw(dws, DW_SPI_DR);
                /* Care rx only if the transfer's original "rx" is not null */
                if (dws->rx_end - dws->len) {
                        if (dws->n_bytes == 1)
                                *(u8 *)(dws->rx) = rxw;
                        else
                                *(u16 *)(dws->rx) = rxw;
                }
                dws->rx += dws->n_bytes;
        }
}

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

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

/*
 * Note: first step is the protocol driver prepares
 * a dma-capable memory, and this func just need translate
 * the virt addr to physical
 */
static int map_dma_buffers(struct dw_spi *dws)
{
        if (!dws->cur_msg->is_dma_mapped
                || !dws->dma_inited
                || !dws->cur_chip->enable_dma
                || !dws->dma_ops)
                return 0;

        if (dws->cur_transfer->tx_dma)
                dws->tx_dma = dws->cur_transfer->tx_dma;

        if (dws->cur_transfer->rx_dma)
                dws->rx_dma = dws->cur_transfer->rx_dma;

        return 1;
}

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

        spin_lock_irqsave(&dws->lock, flags);
        msg = dws->cur_msg;
        dws->cur_msg = NULL;
        dws->cur_transfer = NULL;
        dws->prev_chip = dws->cur_chip;
        dws->cur_chip = NULL;
        dws->dma_mapped = 0;
        queue_work(dws->workqueue, &dws->pump_messages);
        spin_unlock_irqrestore(&dws->lock, flags);

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

        if (!last_transfer->cs_change && dws->cs_control)
                dws->cs_control(MRST_SPI_DEASSERT);

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

static void int_error_stop(struct dw_spi *dws, const char *msg)
{
        /* Stop the hw */
        spi_enable_chip(dws, 0);

        dev_err(&dws->master->dev, "%s\n", msg);
        dws->cur_msg->state = ERROR_STATE;
        tasklet_schedule(&dws->pump_transfers);
}

void dw_spi_xfer_done(struct dw_spi *dws)
{
        /* Update total byte transferred return count actual bytes read */
        dws->cur_msg->actual_length += dws->len;

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

        /* Handle end of message */
        if (dws->cur_msg->state == DONE_STATE) {
                dws->cur_msg->status = 0;
                giveback(dws);
        } else
                tasklet_schedule(&dws->pump_transfers);
}
EXPORT_SYMBOL_GPL(dw_spi_xfer_done);

static irqreturn_t interrupt_transfer(struct dw_spi *dws)
{
        u16 irq_status = dw_readw(dws, DW_SPI_ISR);

        /* Error handling */
        if (irq_status & (SPI_INT_TXOI | SPI_INT_RXOI | SPI_INT_RXUI)) {
                dw_readw(dws, DW_SPI_TXOICR);
                dw_readw(dws, DW_SPI_RXOICR);
                dw_readw(dws, DW_SPI_RXUICR);
                int_error_stop(dws, "interrupt_transfer: fifo overrun/underrun");
                return IRQ_HANDLED;
        }

        dw_reader(dws);
        if (dws->rx_end == dws->rx) {
                spi_mask_intr(dws, SPI_INT_TXEI);
                dw_spi_xfer_done(dws);
                return IRQ_HANDLED;
        }
        if (irq_status & SPI_INT_TXEI) {
                spi_mask_intr(dws, SPI_INT_TXEI);
                dw_writer(dws);
                /* Enable TX irq always, it will be disabled when RX finished */
                spi_umask_intr(dws, SPI_INT_TXEI);
        }

        return IRQ_HANDLED;
}

static irqreturn_t dw_spi_irq(int irq, void *dev_id)
{
        struct dw_spi *dws = dev_id;
        u16 irq_status = dw_readw(dws, DW_SPI_ISR) & 0x3f;

        if (!irq_status)
                return IRQ_NONE;

        if (!dws->cur_msg) {
                spi_mask_intr(dws, SPI_INT_TXEI);
                return IRQ_HANDLED;
        }

        return dws->transfer_handler(dws);
}

/* Must be called inside pump_transfers() */
static void poll_transfer(struct dw_spi *dws)
{
        do {
                dw_writer(dws);
                dw_reader(dws);
                cpu_relax();
        } while (dws->rx_end > dws->rx);

        dw_spi_xfer_done(dws);
}

static void pump_transfers(unsigned long data)
{
        struct dw_spi *dws = (struct dw_spi *)data;
        struct spi_message *message = NULL;
        struct spi_transfer *transfer = NULL;
        struct spi_transfer *previous = NULL;
        struct spi_device *spi = NULL;
        struct chip_data *chip = NULL;
        u8 bits = 0;
        u8 imask = 0;
        u8 cs_change = 0;
        u16 txint_level = 0;
        u16 clk_div = 0;
        u32 speed = 0;
        u32 cr0 = 0;

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

        if (unlikely(!chip->clk_div))
                chip->clk_div = dws->max_freq / chip->speed_hz;

        if (message->state == ERROR_STATE) {
                message->status = -EIO;
                goto early_exit;
        }

        /* Handle end of message */
        if (message->state == DONE_STATE) {
                message->status = 0;
                goto early_exit;
        }

        /* Delay if requested at end of transfer*/
        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);
        }

        dws->n_bytes = chip->n_bytes;
        dws->dma_width = chip->dma_width;
        dws->cs_control = chip->cs_control;

        dws->rx_dma = transfer->rx_dma;
        dws->tx_dma = transfer->tx_dma;
        dws->tx = (void *)transfer->tx_buf;
        dws->tx_end = dws->tx + transfer->len;
        dws->rx = transfer->rx_buf;
        dws->rx_end = dws->rx + transfer->len;
        dws->cs_change = transfer->cs_change;
        dws->len = dws->cur_transfer->len;
        if (chip != dws->prev_chip)
                cs_change = 1;

        cr0 = chip->cr0;

        /* Handle per transfer options for bpw and speed */
        if (transfer->speed_hz) {
                speed = chip->speed_hz;

                if (transfer->speed_hz != speed) {
                        speed = transfer->speed_hz;
                        if (speed > dws->max_freq) {
                                printk(KERN_ERR "MRST SPI0: unsupported"
                                        "freq: %dHz\n", speed);
                                message->status = -EIO;
                                goto early_exit;
                        }

                        /* clk_div doesn't support odd number */
                        clk_div = dws->max_freq / speed;
                        clk_div = (clk_div + 1) & 0xfffe;

                        chip->speed_hz = speed;
                        chip->clk_div = clk_div;
                }
        }
        if (transfer->bits_per_word) {
                bits = transfer->bits_per_word;

                switch (bits) {
                case 8:
                case 16:
                        dws->n_bytes = dws->dma_width = bits >> 3;
                        break;
                default:
                        printk(KERN_ERR "MRST SPI0: unsupported bits:"
                                "%db\n", bits);
                        message->status = -EIO;
                        goto early_exit;
                }

                cr0 = (bits - 1)
                        | (chip->type << SPI_FRF_OFFSET)
                        | (spi->mode << SPI_MODE_OFFSET)
                        | (chip->tmode << SPI_TMOD_OFFSET);
        }
        message->state = RUNNING_STATE;

        /*
         * Adjust transfer mode if necessary. Requires platform dependent
         * chipselect mechanism.
         */
        if (dws->cs_control) {
                if (dws->rx && dws->tx)
                        chip->tmode = SPI_TMOD_TR;
                else if (dws->rx)
                        chip->tmode = SPI_TMOD_RO;
                else
                        chip->tmode = SPI_TMOD_TO;

                cr0 &= ~SPI_TMOD_MASK;
                cr0 |= (chip->tmode << SPI_TMOD_OFFSET);
        }

        /* Check if current transfer is a DMA transaction */
        dws->dma_mapped = map_dma_buffers(dws);

        /*
         * Interrupt mode
         * we only need set the TXEI IRQ, as TX/RX always happen syncronizely
         */
        if (!dws->dma_mapped && !chip->poll_mode) {
                int templen = dws->len / dws->n_bytes;
                txint_level = dws->fifo_len / 2;
                txint_level = (templen > txint_level) ? txint_level : templen;

                imask |= SPI_INT_TXEI | SPI_INT_TXOI | SPI_INT_RXUI | SPI_INT_RXOI;
                dws->transfer_handler = interrupt_transfer;
        }

        /*
         * Reprogram registers only if
         *      1. chip select changes
         *      2. clk_div is changed
         *      3. control value changes
         */
        if (dw_readw(dws, DW_SPI_CTRL0) != cr0 || cs_change || clk_div || imask) {
                spi_enable_chip(dws, 0);

                if (dw_readw(dws, DW_SPI_CTRL0) != cr0)
                        dw_writew(dws, DW_SPI_CTRL0, cr0);

                spi_set_clk(dws, clk_div ? clk_div : chip->clk_div);
                spi_chip_sel(dws, spi->chip_select);

                /* Set the interrupt mask, for poll mode just disable all int */
                spi_mask_intr(dws, 0xff);
                if (imask)
                        spi_umask_intr(dws, imask);
                if (txint_level)
                        dw_writew(dws, DW_SPI_TXFLTR, txint_level);

                spi_enable_chip(dws, 1);
                if (cs_change)
                        dws->prev_chip = chip;
        }

        if (dws->dma_mapped)
                dws->dma_ops->dma_transfer(dws, cs_change);

        if (chip->poll_mode)
                poll_transfer(dws);

        return;

early_exit:
        giveback(dws);
        return;
}

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

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

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

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

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

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

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

/* spi_device use this to queue in their spi_msg */
static int dw_spi_transfer(struct spi_device *spi, struct spi_message *msg)
{
        struct dw_spi *dws = spi_master_get_devdata(spi->master);
        unsigned long flags;

        spin_lock_irqsave(&dws->lock, flags);

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

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

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

        if (dws->run == QUEUE_RUNNING && !dws->busy) {

                if (dws->cur_transfer || dws->cur_msg)
                        queue_work(dws->workqueue,
                                        &dws->pump_messages);
                else {
                        /* If no other data transaction in air, just go */
                        spin_unlock_irqrestore(&dws->lock, flags);
                        pump_messages(&dws->pump_messages);
                        return 0;
                }
        }

        spin_unlock_irqrestore(&dws->lock, flags);
        return 0;
}

/* This may be called twice for each spi dev */
static int dw_spi_setup(struct spi_device *spi)
{
        struct dw_spi_chip *chip_info = NULL;
        struct chip_data *chip;

        if (spi->bits_per_word != 8 && spi->bits_per_word != 16)
                return -EINVAL;

        /* Only alloc on first setup */
        chip = spi_get_ctldata(spi);
        if (!chip) {
                chip = kzalloc(sizeof(struct chip_data), GFP_KERNEL);
                if (!chip)
                        return -ENOMEM;
        }

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

        /* chip_info doesn't always exist */
        if (chip_info) {
                if (chip_info->cs_control)
                        chip->cs_control = chip_info->cs_control;

                chip->poll_mode = chip_info->poll_mode;
                chip->type = chip_info->type;

                chip->rx_threshold = 0;
                chip->tx_threshold = 0;

                chip->enable_dma = chip_info->enable_dma;
        }

        if (spi->bits_per_word <= 8) {
                chip->n_bytes = 1;
                chip->dma_width = 1;
        } else if (spi->bits_per_word <= 16) {
                chip->n_bytes = 2;
                chip->dma_width = 2;
        } else {
                /* Never take >16b case for MRST SPIC */
                dev_err(&spi->dev, "invalid wordsize\n");
                return -EINVAL;
        }
        chip->bits_per_word = spi->bits_per_word;

        if (!spi->max_speed_hz) {
                dev_err(&spi->dev, "No max speed HZ parameter\n");
                return -EINVAL;
        }
        chip->speed_hz = spi->max_speed_hz;

        chip->tmode = 0; /* Tx & Rx */
        /* Default SPI mode is SCPOL = 0, SCPH = 0 */
        chip->cr0 = (chip->bits_per_word - 1)
                        | (chip->type << SPI_FRF_OFFSET)
                        | (spi->mode  << SPI_MODE_OFFSET)
                        | (chip->tmode << SPI_TMOD_OFFSET);

        spi_set_ctldata(spi, chip);
        return 0;
}

static void dw_spi_cleanup(struct spi_device *spi)
{
        struct chip_data *chip = spi_get_ctldata(spi);
        kfree(chip);
}

static int init_queue(struct dw_spi *dws)
{
        INIT_LIST_HEAD(&dws->queue);
        spin_lock_init(&dws->lock);

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

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

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

        return 0;
}

static int start_queue(struct dw_spi *dws)
{
        unsigned long flags;

        spin_lock_irqsave(&dws->lock, flags);

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

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

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

        return 0;
}

static int stop_queue(struct dw_spi *dws)
{
        unsigned long flags;
        unsigned limit = 50;
        int status = 0;

        spin_lock_irqsave(&dws->lock, flags);
        dws->run = QUEUE_STOPPED;
        while ((!list_empty(&dws->queue) || dws->busy) && limit--) {
                spin_unlock_irqrestore(&dws->lock, flags);
                msleep(10);
                spin_lock_irqsave(&dws->lock, flags);
        }

        if (!list_empty(&dws->queue) || dws->busy)
                status = -EBUSY;
        spin_unlock_irqrestore(&dws->lock, flags);

        return status;
}

static int destroy_queue(struct dw_spi *dws)
{
        int status;

        status = stop_queue(dws);
        if (status != 0)
                return status;
        destroy_workqueue(dws->workqueue);
        return 0;
}

/* Restart the controller, disable all interrupts, clean rx fifo */
static void spi_hw_init(struct dw_spi *dws)
{
        spi_enable_chip(dws, 0);
        spi_mask_intr(dws, 0xff);
        spi_enable_chip(dws, 1);

        /*
         * Try to detect the FIFO depth if not set by interface driver,
         * the depth could be from 2 to 256 from HW spec
         */
        if (!dws->fifo_len) {
                u32 fifo;
                for (fifo = 2; fifo <= 257; fifo++) {
                        dw_writew(dws, DW_SPI_TXFLTR, fifo);
                        if (fifo != dw_readw(dws, DW_SPI_TXFLTR))
                                break;
                }

                dws->fifo_len = (fifo == 257) ? 0 : fifo;
                dw_writew(dws, DW_SPI_TXFLTR, 0);
        }
}

int dw_spi_add_host(struct dw_spi *dws)
{
        struct spi_master *master;
        int ret;

        BUG_ON(dws == NULL);

        master = spi_alloc_master(dws->parent_dev, 0);
        if (!master) {
                ret = -ENOMEM;
                goto exit;
        }

        dws->master = master;
        dws->type = SSI_MOTO_SPI;
        dws->prev_chip = NULL;
        dws->dma_inited = 0;
        dws->dma_addr = (dma_addr_t)(dws->paddr + 0x60);
        snprintf(dws->name, sizeof(dws->name), "dw_spi%d",
                        dws->bus_num);

        ret = request_irq(dws->irq, dw_spi_irq, IRQF_SHARED,
                        dws->name, dws);
        if (ret < 0) {
                dev_err(&master->dev, "can not get IRQ\n");
                goto err_free_master;
        }

        master->mode_bits = SPI_CPOL | SPI_CPHA;
        master->bus_num = dws->bus_num;
        master->num_chipselect = dws->num_cs;
        master->cleanup = dw_spi_cleanup;
        master->setup = dw_spi_setup;
        master->transfer = dw_spi_transfer;

        /* Basic HW init */
        spi_hw_init(dws);

        if (dws->dma_ops && dws->dma_ops->dma_init) {
                ret = dws->dma_ops->dma_init(dws);
                if (ret) {
                        dev_warn(&master->dev, "DMA init failed\n");
                        dws->dma_inited = 0;
                }
        }

        /* Initial and start queue */
        ret = init_queue(dws);
        if (ret) {
                dev_err(&master->dev, "problem initializing queue\n");
                goto err_diable_hw;
        }
        ret = start_queue(dws);
        if (ret) {
                dev_err(&master->dev, "problem starting queue\n");
                goto err_diable_hw;
        }

        spi_master_set_devdata(master, dws);
        ret = spi_register_master(master);
        if (ret) {
                dev_err(&master->dev, "problem registering spi master\n");
                goto err_queue_alloc;
        }

        mrst_spi_debugfs_init(dws);
        return 0;

err_queue_alloc:
        destroy_queue(dws);
        if (dws->dma_ops && dws->dma_ops->dma_exit)
                dws->dma_ops->dma_exit(dws);
err_diable_hw:
        spi_enable_chip(dws, 0);
        free_irq(dws->irq, dws);
err_free_master:
        spi_master_put(master);
exit:
        return ret;
}
EXPORT_SYMBOL_GPL(dw_spi_add_host);

void dw_spi_remove_host(struct dw_spi *dws)
{
        int status = 0;

        if (!dws)
                return;
        mrst_spi_debugfs_remove(dws);

        /* Remove the queue */
        status = destroy_queue(dws);
        if (status != 0)
                dev_err(&dws->master->dev, "dw_spi_remove: workqueue will not "
                        "complete, message memory not freed\n");

        if (dws->dma_ops && dws->dma_ops->dma_exit)
                dws->dma_ops->dma_exit(dws);
        spi_enable_chip(dws, 0);
        /* Disable clk */
        spi_set_clk(dws, 0);
        free_irq(dws->irq, dws);

        /* Disconnect from the SPI framework */
        spi_unregister_master(dws->master);
}
EXPORT_SYMBOL_GPL(dw_spi_remove_host);

int dw_spi_suspend_host(struct dw_spi *dws)
{
        int ret = 0;

        ret = stop_queue(dws);
        if (ret)
                return ret;
        spi_enable_chip(dws, 0);
        spi_set_clk(dws, 0);
        return ret;
}
EXPORT_SYMBOL_GPL(dw_spi_suspend_host);

int dw_spi_resume_host(struct dw_spi *dws)
{
        int ret;

        spi_hw_init(dws);
        ret = start_queue(dws);
        if (ret)
                dev_err(&dws->master->dev, "fail to start queue (%d)\n", ret);
        return ret;
}
EXPORT_SYMBOL_GPL(dw_spi_resume_host);

MODULE_AUTHOR("Feng Tang <feng.tang@intel.com>");
MODULE_DESCRIPTION("Driver for DesignWare SPI controller core");
MODULE_LICENSE("GPL v2");