/*
 * drivers/spi/amba-pl022.c
 *
 * A driver for the ARM PL022 PrimeCell SSP/SPI bus master.
 *
 * Copyright (C) 2008-2009 ST-Ericsson AB
 * Copyright (C) 2006 STMicroelectronics Pvt. Ltd.
 *
 * Author: Linus Walleij <linus.walleij@stericsson.com>
 *
 * Initial version inspired by:
 *      linux-2.6.17-rc3-mm1/drivers/spi/pxa2xx_spi.c
 * Initial adoption to PL022 by:
 *      Sachin Verma <sachin.verma@st.com>
 *
 * 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.
 */

/*
 * TODO:
 * - add timeout on polled transfers
 * - add generic DMA framework support
 */

#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/spi/spi.h>
#include <linux/workqueue.h>
#include <linux/delay.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/amba/bus.h>
#include <linux/amba/pl022.h>
#include <linux/io.h>

/*
 * This macro is used to define some register default values.
 * reg is masked with mask, the OR:ed with an (again masked)
 * val shifted sb steps to the left.
 */
#define SSP_WRITE_BITS(reg, val, mask, sb) \
 ((reg) = (((reg) & ~(mask)) | (((val)<<(sb)) & (mask))))

/*
 * This macro is also used to define some default values.
 * It will just shift val by sb steps to the left and mask
 * the result with mask.
 */
#define GEN_MASK_BITS(val, mask, sb) \
 (((val)<<(sb)) & (mask))

#define DRIVE_TX                0
#define DO_NOT_DRIVE_TX         1

#define DO_NOT_QUEUE_DMA        0
#define QUEUE_DMA               1

#define RX_TRANSFER             1
#define TX_TRANSFER             2

/*
 * Macros to access SSP Registers with their offsets
 */
#define SSP_CR0(r)      (r + 0x000)
#define SSP_CR1(r)      (r + 0x004)
#define SSP_DR(r)       (r + 0x008)
#define SSP_SR(r)       (r + 0x00C)
#define SSP_CPSR(r)     (r + 0x010)
#define SSP_IMSC(r)     (r + 0x014)
#define SSP_RIS(r)      (r + 0x018)
#define SSP_MIS(r)      (r + 0x01C)
#define SSP_ICR(r)      (r + 0x020)
#define SSP_DMACR(r)    (r + 0x024)
#define SSP_ITCR(r)     (r + 0x080)
#define SSP_ITIP(r)     (r + 0x084)
#define SSP_ITOP(r)     (r + 0x088)
#define SSP_TDR(r)      (r + 0x08C)

#define SSP_PID0(r)     (r + 0xFE0)
#define SSP_PID1(r)     (r + 0xFE4)
#define SSP_PID2(r)     (r + 0xFE8)
#define SSP_PID3(r)     (r + 0xFEC)

#define SSP_CID0(r)     (r + 0xFF0)
#define SSP_CID1(r)     (r + 0xFF4)
#define SSP_CID2(r)     (r + 0xFF8)
#define SSP_CID3(r)     (r + 0xFFC)

/*
 * SSP Control Register 0  - SSP_CR0
 */
#define SSP_CR0_MASK_DSS        (0x1FUL << 0)
#define SSP_CR0_MASK_HALFDUP    (0x1UL << 5)
#define SSP_CR0_MASK_SPO        (0x1UL << 6)
#define SSP_CR0_MASK_SPH        (0x1UL << 7)
#define SSP_CR0_MASK_SCR        (0xFFUL << 8)
#define SSP_CR0_MASK_CSS        (0x1FUL << 16)
#define SSP_CR0_MASK_FRF        (0x3UL << 21)

/*
 * SSP Control Register 0  - SSP_CR1
 */
#define SSP_CR1_MASK_LBM        (0x1UL << 0)
#define SSP_CR1_MASK_SSE        (0x1UL << 1)
#define SSP_CR1_MASK_MS         (0x1UL << 2)
#define SSP_CR1_MASK_SOD        (0x1UL << 3)
#define SSP_CR1_MASK_RENDN      (0x1UL << 4)
#define SSP_CR1_MASK_TENDN      (0x1UL << 5)
#define SSP_CR1_MASK_MWAIT      (0x1UL << 6)
#define SSP_CR1_MASK_RXIFLSEL   (0x7UL << 7)
#define SSP_CR1_MASK_TXIFLSEL   (0x7UL << 10)

/*
 * SSP Data Register - SSP_DR
 */
#define SSP_DR_MASK_DATA        0xFFFFFFFF

/*
 * SSP Status Register - SSP_SR
 */
#define SSP_SR_MASK_TFE         (0x1UL << 0) /* Transmit FIFO empty */
#define SSP_SR_MASK_TNF         (0x1UL << 1) /* Transmit FIFO not full */
#define SSP_SR_MASK_RNE         (0x1UL << 2) /* Receive FIFO not empty */
#define SSP_SR_MASK_RFF         (0x1UL << 3) /* Receive FIFO full */
#define SSP_SR_MASK_BSY         (0x1UL << 4) /* Busy Flag */

/*
 * SSP Clock Prescale Register  - SSP_CPSR
 */
#define SSP_CPSR_MASK_CPSDVSR   (0xFFUL << 0)

/*
 * SSP Interrupt Mask Set/Clear Register - SSP_IMSC
 */
#define SSP_IMSC_MASK_RORIM (0x1UL << 0) /* Receive Overrun Interrupt mask */
#define SSP_IMSC_MASK_RTIM  (0x1UL << 1) /* Receive timeout Interrupt mask */
#define SSP_IMSC_MASK_RXIM  (0x1UL << 2) /* Receive FIFO Interrupt mask */
#define SSP_IMSC_MASK_TXIM  (0x1UL << 3) /* Transmit FIFO Interrupt mask */

/*
 * SSP Raw Interrupt Status Register - SSP_RIS
 */
/* Receive Overrun Raw Interrupt status */
#define SSP_RIS_MASK_RORRIS             (0x1UL << 0)
/* Receive Timeout Raw Interrupt status */
#define SSP_RIS_MASK_RTRIS              (0x1UL << 1)
/* Receive FIFO Raw Interrupt status */
#define SSP_RIS_MASK_RXRIS              (0x1UL << 2)
/* Transmit FIFO Raw Interrupt status */
#define SSP_RIS_MASK_TXRIS              (0x1UL << 3)

/*
 * SSP Masked Interrupt Status Register - SSP_MIS
 */
/* Receive Overrun Masked Interrupt status */
#define SSP_MIS_MASK_RORMIS             (0x1UL << 0)
/* Receive Timeout Masked Interrupt status */
#define SSP_MIS_MASK_RTMIS              (0x1UL << 1)
/* Receive FIFO Masked Interrupt status */
#define SSP_MIS_MASK_RXMIS              (0x1UL << 2)
/* Transmit FIFO Masked Interrupt status */
#define SSP_MIS_MASK_TXMIS              (0x1UL << 3)

/*
 * SSP Interrupt Clear Register - SSP_ICR
 */
/* Receive Overrun Raw Clear Interrupt bit */
#define SSP_ICR_MASK_RORIC              (0x1UL << 0)
/* Receive Timeout Clear Interrupt bit */
#define SSP_ICR_MASK_RTIC               (0x1UL << 1)

/*
 * SSP DMA Control Register - SSP_DMACR
 */
/* Receive DMA Enable bit */
#define SSP_DMACR_MASK_RXDMAE           (0x1UL << 0)
/* Transmit DMA Enable bit */
#define SSP_DMACR_MASK_TXDMAE           (0x1UL << 1)

/*
 * SSP Integration Test control Register - SSP_ITCR
 */
#define SSP_ITCR_MASK_ITEN              (0x1UL << 0)
#define SSP_ITCR_MASK_TESTFIFO          (0x1UL << 1)

/*
 * SSP Integration Test Input Register - SSP_ITIP
 */
#define ITIP_MASK_SSPRXD                 (0x1UL << 0)
#define ITIP_MASK_SSPFSSIN               (0x1UL << 1)
#define ITIP_MASK_SSPCLKIN               (0x1UL << 2)
#define ITIP_MASK_RXDMAC                 (0x1UL << 3)
#define ITIP_MASK_TXDMAC                 (0x1UL << 4)
#define ITIP_MASK_SSPTXDIN               (0x1UL << 5)

/*
 * SSP Integration Test output Register - SSP_ITOP
 */
#define ITOP_MASK_SSPTXD                 (0x1UL << 0)
#define ITOP_MASK_SSPFSSOUT              (0x1UL << 1)
#define ITOP_MASK_SSPCLKOUT              (0x1UL << 2)
#define ITOP_MASK_SSPOEn                 (0x1UL << 3)
#define ITOP_MASK_SSPCTLOEn              (0x1UL << 4)
#define ITOP_MASK_RORINTR                (0x1UL << 5)
#define ITOP_MASK_RTINTR                 (0x1UL << 6)
#define ITOP_MASK_RXINTR                 (0x1UL << 7)
#define ITOP_MASK_TXINTR                 (0x1UL << 8)
#define ITOP_MASK_INTR                   (0x1UL << 9)
#define ITOP_MASK_RXDMABREQ              (0x1UL << 10)
#define ITOP_MASK_RXDMASREQ              (0x1UL << 11)
#define ITOP_MASK_TXDMABREQ              (0x1UL << 12)
#define ITOP_MASK_TXDMASREQ              (0x1UL << 13)

/*
 * SSP Test Data Register - SSP_TDR
 */
#define TDR_MASK_TESTDATA               (0xFFFFFFFF)

/*
 * Message State
 * we use the spi_message.state (void *) pointer to
 * hold a single state value, that's why all this
 * (void *) casting is done here.
 */
#define STATE_START                     ((void *) 0)
#define STATE_RUNNING                   ((void *) 1)
#define STATE_DONE                      ((void *) 2)
#define STATE_ERROR                     ((void *) -1)

/*
 * Queue State
 */
#define QUEUE_RUNNING                   (0)
#define QUEUE_STOPPED                   (1)
/*
 * SSP State - Whether Enabled or Disabled
 */
#define SSP_DISABLED                    (0)
#define SSP_ENABLED                     (1)

/*
 * SSP DMA State - Whether DMA Enabled or Disabled
 */
#define SSP_DMA_DISABLED                (0)
#define SSP_DMA_ENABLED                 (1)

/*
 * SSP Clock Defaults
 */
#define NMDK_SSP_DEFAULT_CLKRATE 0x2
#define NMDK_SSP_DEFAULT_PRESCALE 0x40

/*
 * SSP Clock Parameter ranges
 */
#define CPSDVR_MIN 0x02
#define CPSDVR_MAX 0xFE
#define SCR_MIN 0x00
#define SCR_MAX 0xFF

/*
 * SSP Interrupt related Macros
 */
#define DEFAULT_SSP_REG_IMSC  0x0UL
#define DISABLE_ALL_INTERRUPTS DEFAULT_SSP_REG_IMSC
#define ENABLE_ALL_INTERRUPTS (~DEFAULT_SSP_REG_IMSC)

#define CLEAR_ALL_INTERRUPTS  0x3


/*
 * The type of reading going on on this chip
 */
enum ssp_reading {
        READING_NULL,
        READING_U8,
        READING_U16,
        READING_U32
};

/**
 * The type of writing going on on this chip
 */
enum ssp_writing {
        WRITING_NULL,
        WRITING_U8,
        WRITING_U16,
        WRITING_U32
};

/**
 * struct vendor_data - vendor-specific config parameters
 * for PL022 derivates
 * @fifodepth: depth of FIFOs (both)
 * @max_bpw: maximum number of bits per word
 * @unidir: supports unidirection transfers
 */
struct vendor_data {
        int fifodepth;
        int max_bpw;
        bool unidir;
};

/**
 * struct pl022 - This is the private SSP driver data structure
 * @adev: AMBA device model hookup
 * @phybase: The physical memory where the SSP device resides
 * @virtbase: The virtual memory where the SSP is mapped
 * @master: SPI framework hookup
 * @master_info: controller-specific data from machine setup
 * @regs: SSP controller register's virtual address
 * @pump_messages: Work struct for scheduling work to the workqueue
 * @lock: spinlock to syncronise access to driver data
 * @workqueue: a workqueue on which any spi_message request is queued
 * @busy: workqueue is busy
 * @run: workqueue is running
 * @pump_transfers: Tasklet used in Interrupt Transfer mode
 * @cur_msg: Pointer to current spi_message being processed
 * @cur_transfer: Pointer to current spi_transfer
 * @cur_chip: pointer to current clients chip(assigned from controller_state)
 * @tx: current position in TX buffer to be read
 * @tx_end: end position in TX buffer to be read
 * @rx: current position in RX buffer to be written
 * @rx_end: end position in RX buffer to be written
 * @readingtype: the type of read currently going on
 * @writingtype: the type or write currently going on
 */
struct pl022 {
        struct amba_device              *adev;
        struct vendor_data              *vendor;
        resource_size_t                 phybase;
        void __iomem                    *virtbase;
        struct clk                      *clk;
        struct spi_master               *master;
        struct pl022_ssp_controller     *master_info;
        /* Driver message queue */
        struct workqueue_struct         *workqueue;
        struct work_struct              pump_messages;
        spinlock_t                      queue_lock;
        struct list_head                queue;
        int                             busy;
        int                             run;
        /* Message transfer pump */
        struct tasklet_struct           pump_transfers;
        struct spi_message              *cur_msg;
        struct spi_transfer             *cur_transfer;
        struct chip_data                *cur_chip;
        void                            *tx;
        void                            *tx_end;
        void                            *rx;
        void                            *rx_end;
        enum ssp_reading                read;
        enum ssp_writing                write;
};

/**
 * struct chip_data - To maintain runtime state of SSP for each client chip
 * @cr0: Value of control register CR0 of SSP
 * @cr1: Value of control register CR1 of SSP
 * @dmacr: Value of DMA control Register of SSP
 * @cpsr: Value of Clock prescale register
 * @n_bytes: how many bytes(power of 2) reqd for a given data width of client
 * @enable_dma: Whether to enable DMA or not
 * @write: function ptr to be used to write when doing xfer for this chip
 * @read: function ptr to be used to read when doing xfer for this chip
 * @cs_control: chip select callback provided by chip
 * @xfer_type: polling/interrupt/DMA
 *
 * Runtime state of the SSP controller, maintained per chip,
 * This would be set according to the current message that would be served
 */
struct chip_data {
        u16 cr0;
        u16 cr1;
        u16 dmacr;
        u16 cpsr;
        u8 n_bytes;
        u8 enable_dma:1;
        enum ssp_reading read;
        enum ssp_writing write;
        void (*cs_control) (u32 command);
        int xfer_type;
};

/**
 * null_cs_control - Dummy chip select function
 * @command: select/delect the chip
 *
 * If no chip select function is provided by client this is used as dummy
 * chip select
 */
static void null_cs_control(u32 command)
{
        pr_debug("pl022: dummy chip select control, CS=0x%x\n", command);
}

/**
 * giveback - current spi_message is over, schedule next message and call
 * callback of this message. Assumes that caller already
 * set message->status; dma and pio irqs are blocked
 * @pl022: SSP driver private data structure
 */
static void giveback(struct pl022 *pl022)
{
        struct spi_transfer *last_transfer;
        unsigned long flags;
        struct spi_message *msg;
        void (*curr_cs_control) (u32 command);

        /*
         * This local reference to the chip select function
         * is needed because we set curr_chip to NULL
         * as a step toward termininating the message.
         */
        curr_cs_control = pl022->cur_chip->cs_control;
        spin_lock_irqsave(&pl022->queue_lock, flags);
        msg = pl022->cur_msg;
        pl022->cur_msg = NULL;
        pl022->cur_transfer = NULL;
        pl022->cur_chip = NULL;
        queue_work(pl022->workqueue, &pl022->pump_messages);
        spin_unlock_irqrestore(&pl022->queue_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)
                /*
                 * FIXME: This runs in interrupt context.
                 * Is this really smart?
                 */
                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)
                curr_cs_control(SSP_CHIP_DESELECT);
        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(&pl022->queue_lock, flags);
                if (list_empty(&pl022->queue))
                        next_msg = NULL;
                else
                        next_msg = list_entry(pl022->queue.next,
                                        struct spi_message, queue);
                spin_unlock_irqrestore(&pl022->queue_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 == STATE_ERROR)
                        curr_cs_control(SSP_CHIP_DESELECT);
        }
        msg->state = NULL;
        if (msg->complete)
                msg->complete(msg->context);
        /* This message is completed, so let's turn off the clock! */
        clk_disable(pl022->clk);
}

/**
 * flush - flush the FIFO to reach a clean state
 * @pl022: SSP driver private data structure
 */
static int flush(struct pl022 *pl022)
{
        unsigned long limit = loops_per_jiffy << 1;

        dev_dbg(&pl022->adev->dev, "flush\n");
        do {
                while (readw(SSP_SR(pl022->virtbase)) & SSP_SR_MASK_RNE)
                        readw(SSP_DR(pl022->virtbase));
        } while ((readw(SSP_SR(pl022->virtbase)) & SSP_SR_MASK_BSY) && limit--);
        return limit;
}

/**
 * restore_state - Load configuration of current chip
 * @pl022: SSP driver private data structure
 */
static void restore_state(struct pl022 *pl022)
{
        struct chip_data *chip = pl022->cur_chip;

        writew(chip->cr0, SSP_CR0(pl022->virtbase));
        writew(chip->cr1, SSP_CR1(pl022->virtbase));
        writew(chip->dmacr, SSP_DMACR(pl022->virtbase));
        writew(chip->cpsr, SSP_CPSR(pl022->virtbase));
        writew(DISABLE_ALL_INTERRUPTS, SSP_IMSC(pl022->virtbase));
        writew(CLEAR_ALL_INTERRUPTS, SSP_ICR(pl022->virtbase));
}

/**
 * load_ssp_default_config - Load default configuration for SSP
 * @pl022: SSP driver private data structure
 */

/*
 * Default SSP Register Values
 */
#define DEFAULT_SSP_REG_CR0 ( \
        GEN_MASK_BITS(SSP_DATA_BITS_12, SSP_CR0_MASK_DSS, 0)    | \
        GEN_MASK_BITS(SSP_MICROWIRE_CHANNEL_FULL_DUPLEX, SSP_CR0_MASK_HALFDUP, 5) | \
        GEN_MASK_BITS(SSP_CLK_POL_IDLE_LOW, SSP_CR0_MASK_SPO, 6) | \
        GEN_MASK_BITS(SSP_CLK_SECOND_EDGE, SSP_CR0_MASK_SPH, 7) | \
        GEN_MASK_BITS(NMDK_SSP_DEFAULT_CLKRATE, SSP_CR0_MASK_SCR, 8) | \
        GEN_MASK_BITS(SSP_BITS_8, SSP_CR0_MASK_CSS, 16) | \
        GEN_MASK_BITS(SSP_INTERFACE_MOTOROLA_SPI, SSP_CR0_MASK_FRF, 21) \
)

#define DEFAULT_SSP_REG_CR1 ( \
        GEN_MASK_BITS(LOOPBACK_DISABLED, SSP_CR1_MASK_LBM, 0) | \
        GEN_MASK_BITS(SSP_DISABLED, SSP_CR1_MASK_SSE, 1) | \
        GEN_MASK_BITS(SSP_MASTER, SSP_CR1_MASK_MS, 2) | \
        GEN_MASK_BITS(DO_NOT_DRIVE_TX, SSP_CR1_MASK_SOD, 3) | \
        GEN_MASK_BITS(SSP_RX_MSB, SSP_CR1_MASK_RENDN, 4) | \
        GEN_MASK_BITS(SSP_TX_MSB, SSP_CR1_MASK_TENDN, 5) | \
        GEN_MASK_BITS(SSP_MWIRE_WAIT_ZERO, SSP_CR1_MASK_MWAIT, 6) |\
        GEN_MASK_BITS(SSP_RX_1_OR_MORE_ELEM, SSP_CR1_MASK_RXIFLSEL, 7) | \
        GEN_MASK_BITS(SSP_TX_1_OR_MORE_EMPTY_LOC, SSP_CR1_MASK_TXIFLSEL, 10) \
)

#define DEFAULT_SSP_REG_CPSR ( \
        GEN_MASK_BITS(NMDK_SSP_DEFAULT_PRESCALE, SSP_CPSR_MASK_CPSDVSR, 0) \
)

#define DEFAULT_SSP_REG_DMACR (\
        GEN_MASK_BITS(SSP_DMA_DISABLED, SSP_DMACR_MASK_RXDMAE, 0) | \
        GEN_MASK_BITS(SSP_DMA_DISABLED, SSP_DMACR_MASK_TXDMAE, 1) \
)


static void load_ssp_default_config(struct pl022 *pl022)
{
        writew(DEFAULT_SSP_REG_CR0, SSP_CR0(pl022->virtbase));
        writew(DEFAULT_SSP_REG_CR1, SSP_CR1(pl022->virtbase));
        writew(DEFAULT_SSP_REG_DMACR, SSP_DMACR(pl022->virtbase));
        writew(DEFAULT_SSP_REG_CPSR, SSP_CPSR(pl022->virtbase));
        writew(DISABLE_ALL_INTERRUPTS, SSP_IMSC(pl022->virtbase));
        writew(CLEAR_ALL_INTERRUPTS, SSP_ICR(pl022->virtbase));
}

/**
 * This will write to TX and read from RX according to the parameters
 * set in pl022.
 */
static void readwriter(struct pl022 *pl022)
{

        /*
         * The FIFO depth is different inbetween primecell variants.
         * I believe filling in too much in the FIFO might cause
         * errons in 8bit wide transfers on ARM variants (just 8 words
         * FIFO, means only 8x8 = 64 bits in FIFO) at least.
         *
         * FIXME: currently we have no logic to account for this.
         * perhaps there is even something broken in HW regarding
         * 8bit transfers (it doesn't fail on 16bit) so this needs
         * more investigation...
         */
        dev_dbg(&pl022->adev->dev,
                "%s, rx: %p, rxend: %p, tx: %p, txend: %p\n",
                __func__, pl022->rx, pl022->rx_end, pl022->tx, pl022->tx_end);

        /* Read as much as you can */
        while ((readw(SSP_SR(pl022->virtbase)) & SSP_SR_MASK_RNE)
               && (pl022->rx < pl022->rx_end)) {
                switch (pl022->read) {
                case READING_NULL:
                        readw(SSP_DR(pl022->virtbase));
                        break;
                case READING_U8:
                        *(u8 *) (pl022->rx) =
                                readw(SSP_DR(pl022->virtbase)) & 0xFFU;
                        break;
                case READING_U16:
                        *(u16 *) (pl022->rx) =
                                (u16) readw(SSP_DR(pl022->virtbase));
                        break;
                case READING_U32:
                        *(u32 *) (pl022->rx) =
                                readl(SSP_DR(pl022->virtbase));
                        break;
                }
                pl022->rx += (pl022->cur_chip->n_bytes);
        }
        /*
         * Write as much as you can, while keeping an eye on the RX FIFO!
         */
        while ((readw(SSP_SR(pl022->virtbase)) & SSP_SR_MASK_TNF)
               && (pl022->tx < pl022->tx_end)) {
                switch (pl022->write) {
                case WRITING_NULL:
                        writew(0x0, SSP_DR(pl022->virtbase));
                        break;
                case WRITING_U8:
                        writew(*(u8 *) (pl022->tx), SSP_DR(pl022->virtbase));
                        break;
                case WRITING_U16:
                        writew((*(u16 *) (pl022->tx)), SSP_DR(pl022->virtbase));
                        break;
                case WRITING_U32:
                        writel(*(u32 *) (pl022->tx), SSP_DR(pl022->virtbase));
                        break;
                }
                pl022->tx += (pl022->cur_chip->n_bytes);
                /*
                 * This inner reader takes care of things appearing in the RX
                 * FIFO as we're transmitting. This will happen a lot since the
                 * clock starts running when you put things into the TX FIFO,
                 * and then things are continously clocked into the RX FIFO.
                 */
                while ((readw(SSP_SR(pl022->virtbase)) & SSP_SR_MASK_RNE)
                       && (pl022->rx < pl022->rx_end)) {
                        switch (pl022->read) {
                        case READING_NULL:
                                readw(SSP_DR(pl022->virtbase));
                                break;
                        case READING_U8:
                                *(u8 *) (pl022->rx) =
                                        readw(SSP_DR(pl022->virtbase)) & 0xFFU;
                                break;
                        case READING_U16:
                                *(u16 *) (pl022->rx) =
                                        (u16) readw(SSP_DR(pl022->virtbase));
                                break;
                        case READING_U32:
                                *(u32 *) (pl022->rx) =
                                        readl(SSP_DR(pl022->virtbase));
                                break;
                        }
                        pl022->rx += (pl022->cur_chip->n_bytes);
                }
        }
        /*
         * When we exit here the TX FIFO should be full and the RX FIFO
         * should be empty
         */
}


/**
 * next_transfer - Move to the Next transfer in the current spi message
 * @pl022: SSP driver private data structure
 *
 * This function moves though the linked list of spi transfers in the
 * current spi message and returns with the state of current spi
 * message i.e whether its last transfer is done(STATE_DONE) or
 * Next transfer is ready(STATE_RUNNING)
 */
static void *next_transfer(struct pl022 *pl022)
{
        struct spi_message *msg = pl022->cur_msg;
        struct spi_transfer *trans = pl022->cur_transfer;

        /* Move to next transfer */
        if (trans->transfer_list.next != &msg->transfers) {
                pl022->cur_transfer =
                    list_entry(trans->transfer_list.next,
                               struct spi_transfer, transfer_list);
                return STATE_RUNNING;
        }
        return STATE_DONE;
}
/**
 * pl022_interrupt_handler - Interrupt handler for SSP controller
 *
 * This function handles interrupts generated for an interrupt based transfer.
 * If a receive overrun (ROR) interrupt is there then we disable SSP, flag the
 * current message's state as STATE_ERROR and schedule the tasklet
 * pump_transfers which will do the postprocessing of the current message by
 * calling giveback(). Otherwise it reads data from RX FIFO till there is no
 * more data, and writes data in TX FIFO till it is not full. If we complete
 * the transfer we move to the next transfer and schedule the tasklet.
 */
static irqreturn_t pl022_interrupt_handler(int irq, void *dev_id)
{
        struct pl022 *pl022 = dev_id;
        struct spi_message *msg = pl022->cur_msg;
        u16 irq_status = 0;
        u16 flag = 0;

        if (unlikely(!msg)) {
                dev_err(&pl022->adev->dev,
                        "bad message state in interrupt handler");
                /* Never fail */
                return IRQ_HANDLED;
        }

        /* Read the Interrupt Status Register */
        irq_status = readw(SSP_MIS(pl022->virtbase));

        if (unlikely(!irq_status))
                return IRQ_NONE;

        /* This handles the error code interrupts */
        if (unlikely(irq_status & SSP_MIS_MASK_RORMIS)) {
                /*
                 * Overrun interrupt - bail out since our Data has been
                 * corrupted
                 */
                dev_err(&pl022->adev->dev,
                        "FIFO overrun\n");
                if (readw(SSP_SR(pl022->virtbase)) & SSP_SR_MASK_RFF)
                        dev_err(&pl022->adev->dev,
                                "RXFIFO is full\n");
                if (readw(SSP_SR(pl022->virtbase)) & SSP_SR_MASK_TNF)
                        dev_err(&pl022->adev->dev,
                                "TXFIFO is full\n");

                /*
                 * Disable and clear interrupts, disable SSP,
                 * mark message with bad status so it can be
                 * retried.
                 */
                writew(DISABLE_ALL_INTERRUPTS,
                       SSP_IMSC(pl022->virtbase));
                writew(CLEAR_ALL_INTERRUPTS, SSP_ICR(pl022->virtbase));
                writew((readw(SSP_CR1(pl022->virtbase)) &
                        (~SSP_CR1_MASK_SSE)), SSP_CR1(pl022->virtbase));
                msg->state = STATE_ERROR;

                /* Schedule message queue handler */
                tasklet_schedule(&pl022->pump_transfers);
                return IRQ_HANDLED;
        }

        readwriter(pl022);

        if ((pl022->tx == pl022->tx_end) && (flag == 0)) {
                flag = 1;
                /* Disable Transmit interrupt */
                writew(readw(SSP_IMSC(pl022->virtbase)) &
                       (~SSP_IMSC_MASK_TXIM),
                       SSP_IMSC(pl022->virtbase));
        }

        /*
         * Since all transactions must write as much as shall be read,
         * we can conclude the entire transaction once RX is complete.
         * At this point, all TX will always be finished.
         */
        if (pl022->rx >= pl022->rx_end) {
                writew(DISABLE_ALL_INTERRUPTS,
                       SSP_IMSC(pl022->virtbase));
                writew(CLEAR_ALL_INTERRUPTS, SSP_ICR(pl022->virtbase));
                if (unlikely(pl022->rx > pl022->rx_end)) {
                        dev_warn(&pl022->adev->dev, "read %u surplus "
                                 "bytes (did you request an odd "
                                 "number of bytes on a 16bit bus?)\n",
                                 (u32) (pl022->rx - pl022->rx_end));
                }
                /* Update total bytes transfered */
                msg->actual_length += pl022->cur_transfer->len;
                if (pl022->cur_transfer->cs_change)
                        pl022->cur_chip->
                                cs_control(SSP_CHIP_DESELECT);
                /* Move to next transfer */
                msg->state = next_transfer(pl022);
                tasklet_schedule(&pl022->pump_transfers);
                return IRQ_HANDLED;
        }

        return IRQ_HANDLED;
}

/**
 * This sets up the pointers to memory for the next message to
 * send out on the SPI bus.
 */
static int set_up_next_transfer(struct pl022 *pl022,
                                struct spi_transfer *transfer)
{
        int residue;

        /* Sanity check the message for this bus width */
        residue = pl022->cur_transfer->len % pl022->cur_chip->n_bytes;
        if (unlikely(residue != 0)) {
                dev_err(&pl022->adev->dev,
                        "message of %u bytes to transmit but the current "
                        "chip bus has a data width of %u bytes!\n",
                        pl022->cur_transfer->len,
                        pl022->cur_chip->n_bytes);
                dev_err(&pl022->adev->dev, "skipping this message\n");
                return -EIO;
        }
        pl022->tx = (void *)transfer->tx_buf;
        pl022->tx_end = pl022->tx + pl022->cur_transfer->len;
        pl022->rx = (void *)transfer->rx_buf;
        pl022->rx_end = pl022->rx + pl022->cur_transfer->len;
        pl022->write =
            pl022->tx ? pl022->cur_chip->write : WRITING_NULL;
        pl022->read = pl022->rx ? pl022->cur_chip->read : READING_NULL;
        return 0;
}

/**
 * pump_transfers - Tasklet function which schedules next interrupt transfer
 * when running in interrupt transfer mode.
 * @data: SSP driver private data structure
 *
 */
static void pump_transfers(unsigned long data)
{
        struct pl022 *pl022 = (struct pl022 *) data;
        struct spi_message *message = NULL;
        struct spi_transfer *transfer = NULL;
        struct spi_transfer *previous = NULL;

        /* Get current state information */
        message = pl022->cur_msg;
        transfer = pl022->cur_transfer;

        /* Handle for abort */
        if (message->state == STATE_ERROR) {
                message->status = -EIO;
                giveback(pl022);
                return;
        }

        /* Handle end of message */
        if (message->state == STATE_DONE) {
                message->status = 0;
                giveback(pl022);
                return;
        }

        /* Delay if requested at end of transfer before CS change */
        if (message->state == STATE_RUNNING) {
                previous = list_entry(transfer->transfer_list.prev,
                                        struct spi_transfer,
                                        transfer_list);
                if (previous->delay_usecs)
                        /*
                         * FIXME: This runs in interrupt context.
                         * Is this really smart?
                         */
                        udelay(previous->delay_usecs);

                /* Drop chip select only if cs_change is requested */
                if (previous->cs_change)
                        pl022->cur_chip->cs_control(SSP_CHIP_SELECT);
        } else {
                /* STATE_START */
                message->state = STATE_RUNNING;
        }

        if (set_up_next_transfer(pl022, transfer)) {
                message->state = STATE_ERROR;
                message->status = -EIO;
                giveback(pl022);
                return;
        }
        /* Flush the FIFOs and let's go! */
        flush(pl022);
        writew(ENABLE_ALL_INTERRUPTS, SSP_IMSC(pl022->virtbase));
}

/**
 * NOT IMPLEMENTED
 * configure_dma - It configures the DMA pipes for DMA transfers
 * @data: SSP driver's private data structure
 *
 */
static int configure_dma(void *data)
{
        struct pl022 *pl022 = data;
        dev_dbg(&pl022->adev->dev, "configure DMA\n");
        return -ENOTSUPP;
}

/**
 * do_dma_transfer - It handles transfers of the current message
 * if it is DMA xfer.
 * NOT FULLY IMPLEMENTED
 * @data: SSP driver's private data structure
 */
static void do_dma_transfer(void *data)
{
        struct pl022 *pl022 = data;

        if (configure_dma(data)) {
                dev_dbg(&pl022->adev->dev, "configuration of DMA Failed!\n");
                goto err_config_dma;
        }

        /* TODO: Implememt DMA setup of pipes here */

        /* Enable target chip, set up transfer */
        pl022->cur_chip->cs_control(SSP_CHIP_SELECT);
        if (set_up_next_transfer(pl022, pl022->cur_transfer)) {
                /* Error path */
                pl022->cur_msg->state = STATE_ERROR;
                pl022->cur_msg->status = -EIO;
                giveback(pl022);
                return;
        }
        /* Enable SSP */
        writew((readw(SSP_CR1(pl022->virtbase)) | SSP_CR1_MASK_SSE),
               SSP_CR1(pl022->virtbase));

        /* TODO: Enable the DMA transfer here */
        return;

 err_config_dma:
        pl022->cur_msg->state = STATE_ERROR;
        pl022->cur_msg->status = -EIO;
        giveback(pl022);
        return;
}

static void do_interrupt_transfer(void *data)
{
        struct pl022 *pl022 = data;

        /* Enable target chip */
        pl022->cur_chip->cs_control(SSP_CHIP_SELECT);
        if (set_up_next_transfer(pl022, pl022->cur_transfer)) {
                /* Error path */
                pl022->cur_msg->state = STATE_ERROR;
                pl022->cur_msg->status = -EIO;
                giveback(pl022);
                return;
        }
        /* Enable SSP, turn on interrupts */
        writew((readw(SSP_CR1(pl022->virtbase)) | SSP_CR1_MASK_SSE),
               SSP_CR1(pl022->virtbase));
        writew(ENABLE_ALL_INTERRUPTS, SSP_IMSC(pl022->virtbase));
}

static void do_polling_transfer(void *data)
{
        struct pl022 *pl022 = data;
        struct spi_message *message = NULL;
        struct spi_transfer *transfer = NULL;
        struct spi_transfer *previous = NULL;
        struct chip_data *chip;

        chip = pl022->cur_chip;
        message = pl022->cur_msg;

        while (message->state != STATE_DONE) {
                /* Handle for abort */
                if (message->state == STATE_ERROR)
                        break;
                transfer = pl022->cur_transfer;

                /* Delay if requested at end of transfer */
                if (message->state == STATE_RUNNING) {
                        previous =
                            list_entry(transfer->transfer_list.prev,
                                       struct spi_transfer, transfer_list);
                        if (previous->delay_usecs)
                                udelay(previous->delay_usecs);
                        if (previous->cs_change)
                                pl022->cur_chip->cs_control(SSP_CHIP_SELECT);
                } else {
                        /* STATE_START */
                        message->state = STATE_RUNNING;
                        pl022->cur_chip->cs_control(SSP_CHIP_SELECT);
                }

                /* Configuration Changing Per Transfer */
                if (set_up_next_transfer(pl022, transfer)) {
                        /* Error path */
                        message->state = STATE_ERROR;
                        break;
                }
                /* Flush FIFOs and enable SSP */
                flush(pl022);

                writew((readw(SSP_CR1(pl022->virtbase)) | SSP_CR1_MASK_SSE),
                       SSP_CR1(pl022->virtbase));

                dev_dbg(&pl022->adev->dev, "POLLING TRANSFER ONGOING ... \n");
                /* FIXME: insert a timeout so we don't hang here indefinately */
                while (pl022->tx < pl022->tx_end || pl022->rx < pl022->rx_end)
                        readwriter(pl022);

                /* Update total byte transfered */
                message->actual_length += pl022->cur_transfer->len;
                if (pl022->cur_transfer->cs_change)
                        pl022->cur_chip->cs_control(SSP_CHIP_DESELECT);
                /* Move to next transfer */
                message->state = next_transfer(pl022);
        }

        /* Handle end of message */
        if (message->state == STATE_DONE)
                message->status = 0;
        else
                message->status = -EIO;

        giveback(pl022);
        return;
}

/**
 * pump_messages - Workqueue function which processes spi message queue
 * @data: pointer to private data of SSP driver
 *
 * This function checks if there is any spi message in the queue that
 * needs processing and delegate control to appropriate function
 * do_polling_transfer()/do_interrupt_transfer()/do_dma_transfer()
 * based on the kind of the transfer
 *
 */
static void pump_messages(struct work_struct *work)
{
        struct pl022 *pl022 =
                container_of(work, struct pl022, pump_messages);
        unsigned long flags;

        /* Lock queue and check for queue work */
        spin_lock_irqsave(&pl022->queue_lock, flags);
        if (list_empty(&pl022->queue) || pl022->run == QUEUE_STOPPED) {
                pl022->busy = 0;
                spin_unlock_irqrestore(&pl022->queue_lock, flags);
                return;
        }
        /* Make sure we are not already running a message */
        if (pl022->cur_msg) {
                spin_unlock_irqrestore(&pl022->queue_lock, flags);
                return;
        }
        /* Extract head of queue */
        pl022->cur_msg =
            list_entry(pl022->queue.next, struct spi_message, queue);

        list_del_init(&pl022->cur_msg->queue);
        pl022->busy = 1;
        spin_unlock_irqrestore(&pl022->queue_lock, flags);

        /* Initial message state */
        pl022->cur_msg->state = STATE_START;
        pl022->cur_transfer = list_entry(pl022->cur_msg->transfers.next,
                                            struct spi_transfer,
                                            transfer_list);

        /* Setup the SPI using the per chip configuration */
        pl022->cur_chip = spi_get_ctldata(pl022->cur_msg->spi);
        /*
         * We enable the clock here, then the clock will be disabled when
         * giveback() is called in each method (poll/interrupt/DMA)
         */
        clk_enable(pl022->clk);
        restore_state(pl022);
        flush(pl022);

        if (pl022->cur_chip->xfer_type == POLLING_TRANSFER)
                do_polling_transfer(pl022);
        else if (pl022->cur_chip->xfer_type == INTERRUPT_TRANSFER)
                do_interrupt_transfer(pl022);
        else
                do_dma_transfer(pl022);
}


static int __init init_queue(struct pl022 *pl022)
{
        INIT_LIST_HEAD(&pl022->queue);
        spin_lock_init(&pl022->queue_lock);

        pl022->run = QUEUE_STOPPED;
        pl022->busy = 0;

        tasklet_init(&pl022->pump_transfers,
                        pump_transfers, (unsigned long)pl022);

        INIT_WORK(&pl022->pump_messages, pump_messages);
        pl022->workqueue = create_singlethread_workqueue(
                                        dev_name(pl022->master->dev.parent));
        if (pl022->workqueue == NULL)
                return -EBUSY;

        return 0;
}


static int start_queue(struct pl022 *pl022)
{
        unsigned long flags;

        spin_lock_irqsave(&pl022->queue_lock, flags);

        if (pl022->run == QUEUE_RUNNING || pl022->busy) {
                spin_unlock_irqrestore(&pl022->queue_lock, flags);
                return -EBUSY;
        }

        pl022->run = QUEUE_RUNNING;
        pl022->cur_msg = NULL;
        pl022->cur_transfer = NULL;
        pl022->cur_chip = NULL;
        spin_unlock_irqrestore(&pl022->queue_lock, flags);

        queue_work(pl022->workqueue, &pl022->pump_messages);

        return 0;
}


static int stop_queue(struct pl022 *pl022)
{
        unsigned long flags;
        unsigned limit = 500;
        int status = 0;

        spin_lock_irqsave(&pl022->queue_lock, flags);

        /* This is a bit lame, but is optimized for the common execution path.
         * A wait_queue on the pl022->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 */
        pl022->run = QUEUE_STOPPED;
        while (!list_empty(&pl022->queue) && pl022->busy && limit--) {
                spin_unlock_irqrestore(&pl022->queue_lock, flags);
                msleep(10);
                spin_lock_irqsave(&pl022->queue_lock, flags);
        }

        if (!list_empty(&pl022->queue) || pl022->busy)
                status = -EBUSY;

        spin_unlock_irqrestore(&pl022->queue_lock, flags);

        return status;
}

static int destroy_queue(struct pl022 *pl022)
{
        int status;

        status = stop_queue(pl022);
        /* 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(pl022->workqueue);

        return 0;
}

static int verify_controller_parameters(struct pl022 *pl022,
                                        struct pl022_config_chip *chip_info)
{
        if ((chip_info->lbm != LOOPBACK_ENABLED)
            && (chip_info->lbm != LOOPBACK_DISABLED)) {
                dev_err(chip_info->dev,
                        "loopback Mode is configured incorrectly\n");
                return -EINVAL;
        }
        if ((chip_info->iface < SSP_INTERFACE_MOTOROLA_SPI)
            || (chip_info->iface > SSP_INTERFACE_UNIDIRECTIONAL)) {
                dev_err(chip_info->dev,
                        "interface is configured incorrectly\n");
                return -EINVAL;
        }
        if ((chip_info->iface == SSP_INTERFACE_UNIDIRECTIONAL) &&
            (!pl022->vendor->unidir)) {
                dev_err(chip_info->dev,
                        "unidirectional mode not supported in this "
                        "hardware version\n");
                return -EINVAL;
        }
        if ((chip_info->hierarchy != SSP_MASTER)
            && (chip_info->hierarchy != SSP_SLAVE)) {
                dev_err(chip_info->dev,
                        "hierarchy is configured incorrectly\n");
                return -EINVAL;
        }
        if (((chip_info->clk_freq).cpsdvsr < CPSDVR_MIN)
            || ((chip_info->clk_freq).cpsdvsr > CPSDVR_MAX)) {
                dev_err(chip_info->dev,
                        "cpsdvsr is configured incorrectly\n");
                return -EINVAL;
        }
        if ((chip_info->endian_rx != SSP_RX_MSB)
            && (chip_info->endian_rx != SSP_RX_LSB)) {
                dev_err(chip_info->dev,
                        "RX FIFO endianess is configured incorrectly\n");
                return -EINVAL;
        }
        if ((chip_info->endian_tx != SSP_TX_MSB)
            && (chip_info->endian_tx != SSP_TX_LSB)) {
                dev_err(chip_info->dev,
                        "TX FIFO endianess is configured incorrectly\n");
                return -EINVAL;
        }
        if ((chip_info->data_size < SSP_DATA_BITS_4)
            || (chip_info->data_size > SSP_DATA_BITS_32)) {
                dev_err(chip_info->dev,
                        "DATA Size is configured incorrectly\n");
                return -EINVAL;
        }
        if ((chip_info->com_mode != INTERRUPT_TRANSFER)
            && (chip_info->com_mode != DMA_TRANSFER)
            && (chip_info->com_mode != POLLING_TRANSFER)) {
                dev_err(chip_info->dev,
                        "Communication mode is configured incorrectly\n");
                return -EINVAL;
        }
        if ((chip_info->rx_lev_trig < SSP_RX_1_OR_MORE_ELEM)
            || (chip_info->rx_lev_trig > SSP_RX_32_OR_MORE_ELEM)) {
                dev_err(chip_info->dev,
                        "RX FIFO Trigger Level is configured incorrectly\n");
                return -EINVAL;
        }
        if ((chip_info->tx_lev_trig < SSP_TX_1_OR_MORE_EMPTY_LOC)
            || (chip_info->tx_lev_trig > SSP_TX_32_OR_MORE_EMPTY_LOC)) {
                dev_err(chip_info->dev,
                        "TX FIFO Trigger Level is configured incorrectly\n");
                return -EINVAL;
        }
        if (chip_info->iface == SSP_INTERFACE_MOTOROLA_SPI) {
                if ((chip_info->clk_phase != SSP_CLK_FIRST_EDGE)
                    && (chip_info->clk_phase != SSP_CLK_SECOND_EDGE)) {
                        dev_err(chip_info->dev,
                                "Clock Phase is configured incorrectly\n");
                        return -EINVAL;
                }
                if ((chip_info->clk_pol != SSP_CLK_POL_IDLE_LOW)
                    && (chip_info->clk_pol != SSP_CLK_POL_IDLE_HIGH)) {
                        dev_err(chip_info->dev,
                                "Clock Polarity is configured incorrectly\n");
                        return -EINVAL;
                }
        }
        if (chip_info->iface == SSP_INTERFACE_NATIONAL_MICROWIRE) {
                if ((chip_info->ctrl_len < SSP_BITS_4)
                    || (chip_info->ctrl_len > SSP_BITS_32)) {
                        dev_err(chip_info->dev,
                                "CTRL LEN is configured incorrectly\n");
                        return -EINVAL;
                }
                if ((chip_info->wait_state != SSP_MWIRE_WAIT_ZERO)
                    && (chip_info->wait_state != SSP_MWIRE_WAIT_ONE)) {
                        dev_err(chip_info->dev,
                                "Wait State is configured incorrectly\n");
                        return -EINVAL;
                }
                if ((chip_info->duplex != SSP_MICROWIRE_CHANNEL_FULL_DUPLEX)
                    && (chip_info->duplex !=
                        SSP_MICROWIRE_CHANNEL_HALF_DUPLEX)) {
                        dev_err(chip_info->dev,
                                "DUPLEX is configured incorrectly\n");
                        return -EINVAL;
                }
        }
        if (chip_info->cs_control == NULL) {
                dev_warn(chip_info->dev,
                        "Chip Select Function is NULL for this chip\n");
                chip_info->cs_control = null_cs_control;
        }
        return 0;
}

/**
 * pl022_transfer - transfer function registered to SPI master framework
 * @spi: spi device which is requesting transfer
 * @msg: spi message which is to handled is queued to driver queue
 *
 * This function is registered to the SPI framework for this SPI master
 * controller. It will queue the spi_message in the queue of driver if
 * the queue is not stopped and return.
 */
static int pl022_transfer(struct spi_device *spi, struct spi_message *msg)
{
        struct pl022 *pl022 = spi_master_get_devdata(spi->master);
        unsigned long flags;

        spin_lock_irqsave(&pl022->queue_lock, flags);

        if (pl022->run == QUEUE_STOPPED) {
                spin_unlock_irqrestore(&pl022->queue_lock, flags);
                return -ESHUTDOWN;
        }
        msg->actual_length = 0;
        msg->status = -EINPROGRESS;
        msg->state = STATE_START;

        list_add_tail(&msg->queue, &pl022->queue);
        if (pl022->run == QUEUE_RUNNING && !pl022->busy)
                queue_work(pl022->workqueue, &pl022->pump_messages);

        spin_unlock_irqrestore(&pl022->queue_lock, flags);
        return 0;
}

static int calculate_effective_freq(struct pl022 *pl022,
                                    int freq,
                                    struct ssp_clock_params *clk_freq)
{
        /* Lets calculate the frequency parameters */
        u16 cpsdvsr = 2;
        u16 scr = 0;
        bool freq_found = false;
        u32 rate;
        u32 max_tclk;
        u32 min_tclk;

        rate = clk_get_rate(pl022->clk);
        /* cpsdvscr = 2 & scr 0 */
        max_tclk = (rate / (CPSDVR_MIN * (1 + SCR_MIN)));
        /* cpsdvsr = 254 & scr = 255 */
        min_tclk = (rate / (CPSDVR_MAX * (1 + SCR_MAX)));

        if ((freq <= max_tclk) && (freq >= min_tclk)) {
                while (cpsdvsr <= CPSDVR_MAX && !freq_found) {
                        while (scr <= SCR_MAX && !freq_found) {
                                if ((rate /
                                     (cpsdvsr * (1 + scr))) > freq)
                                        scr += 1;
                                else {
                                        /*
                                         * This bool is made true when
                                         * effective frequency >=
                                         * target frequency is found
                                         */
                                        freq_found = true;
                                        if ((rate /
                                             (cpsdvsr * (1 + scr))) != freq) {
                                                if (scr == SCR_MIN) {
                                                        cpsdvsr -= 2;
                                                        scr = SCR_MAX;
                                                } else
                                                        scr -= 1;
                                        }
                                }
                        }
                        if (!freq_found) {
                                cpsdvsr += 2;
                                scr = SCR_MIN;
                        }
                }
                if (cpsdvsr != 0) {
                        dev_dbg(&pl022->adev->dev,
                                "SSP Effective Frequency is %u\n",
                                (rate / (cpsdvsr * (1 + scr))));
                        clk_freq->cpsdvsr = (u8) (cpsdvsr & 0xFF);
                        clk_freq->scr = (u8) (scr & 0xFF);
                        dev_dbg(&pl022->adev->dev,
                                "SSP cpsdvsr = %d, scr = %d\n",
                                clk_freq->cpsdvsr, clk_freq->scr);
                }
        } else {
                dev_err(&pl022->adev->dev,
                        "controller data is incorrect: out of range frequency");
                return -EINVAL;
        }
        return 0;
}

/**
 * NOT IMPLEMENTED
 * process_dma_info - Processes the DMA info provided by client drivers
 * @chip_info: chip info provided by client device
 * @chip: Runtime state maintained by the SSP controller for each spi device
 *
 * This function processes and stores DMA config provided by client driver
 * into the runtime state maintained by the SSP controller driver
 */
static int process_dma_info(struct pl022_config_chip *chip_info,
                            struct chip_data *chip)
{
        dev_err(chip_info->dev,
                "cannot process DMA info, DMA not implemented!\n");
        return -ENOTSUPP;
}

/**
 * pl022_setup - setup function registered to SPI master framework
 * @spi: spi device which is requesting setup
 *
 * This function is registered to the SPI framework for this SPI master
 * controller. If it is the first time when setup is called by this device,
 * this function will initialize the runtime state for this chip and save
 * the same in the device structure. Else it will update the runtime info
 * with the updated chip info. Nothing is really being written to the
 * controller hardware here, that is not done until the actual transfer
 * commence.
 */

/* FIXME: JUST GUESSING the spi->mode bits understood by this driver */
#define MODEBITS        (SPI_CPOL | SPI_CPHA | SPI_CS_HIGH \
                        | SPI_LSB_FIRST | SPI_LOOP)

static int pl022_setup(struct spi_device *spi)
{
        struct pl022_config_chip *chip_info;
        struct chip_data *chip;
        int status = 0;
        struct pl022 *pl022 = spi_master_get_devdata(spi->master);

        if (spi->mode & ~MODEBITS) {
                dev_dbg(&spi->dev, "unsupported mode bits %x\n",
                        spi->mode & ~MODEBITS);
                return -EINVAL;
        }

        if (!spi->max_speed_hz)
                return -EINVAL;

        /* Get controller_state if one is supplied */
        chip = spi_get_ctldata(spi);

        if (chip == NULL) {
                chip = kzalloc(sizeof(struct chip_data), GFP_KERNEL);
                if (!chip) {
                        dev_err(&spi->dev,
                                "cannot allocate controller state\n");
                        return -ENOMEM;
                }
                dev_dbg(&spi->dev,
                        "allocated memory for controller's runtime state\n");
        }

        /* Get controller data if one is supplied */
        chip_info = spi->controller_data;

        if (chip_info == NULL) {
                /* spi_board_info.controller_data not is supplied */
                dev_dbg(&spi->dev,
                        "using default controller_data settings\n");

                chip_info =
                        kzalloc(sizeof(struct pl022_config_chip), GFP_KERNEL);

                if (!chip_info) {
                        dev_err(&spi->dev,
                                "cannot allocate controller data\n");
                        status = -ENOMEM;
                        goto err_first_setup;
                }

                dev_dbg(&spi->dev, "allocated memory for controller data\n");

                /* Pointer back to the SPI device */
                chip_info->dev = &spi->dev;
                /*
                 * Set controller data default values:
                 * Polling is supported by default
                 */
                chip_info->lbm = LOOPBACK_DISABLED;
                chip_info->com_mode = POLLING_TRANSFER;
                chip_info->iface = SSP_INTERFACE_MOTOROLA_SPI;
                chip_info->hierarchy = SSP_SLAVE;
                chip_info->slave_tx_disable = DO_NOT_DRIVE_TX;
                chip_info->endian_tx = SSP_TX_LSB;
                chip_info->endian_rx = SSP_RX_LSB;
                chip_info->data_size = SSP_DATA_BITS_12;
                chip_info->rx_lev_trig = SSP_RX_1_OR_MORE_ELEM;
                chip_info->tx_lev_trig = SSP_TX_1_OR_MORE_EMPTY_LOC;
                chip_info->clk_phase = SSP_CLK_SECOND_EDGE;
                chip_info->clk_pol = SSP_CLK_POL_IDLE_LOW;
                chip_info->ctrl_len = SSP_BITS_8;
                chip_info->wait_state = SSP_MWIRE_WAIT_ZERO;
                chip_info->duplex = SSP_MICROWIRE_CHANNEL_FULL_DUPLEX;
                chip_info->cs_control = null_cs_control;
        } else {
                dev_dbg(&spi->dev,
                        "using user supplied controller_data settings\n");
        }

        /*
         * We can override with custom divisors, else we use the board
         * frequency setting
         */
        if ((0 == chip_info->clk_freq.cpsdvsr)
            && (0 == chip_info->clk_freq.scr)) {
                status = calculate_effective_freq(pl022,
                                                  spi->max_speed_hz,
                                                  &chip_info->clk_freq);
                if (status < 0)
                        goto err_config_params;
        } else {
                if ((chip_info->clk_freq.cpsdvsr % 2) != 0)
                        chip_info->clk_freq.cpsdvsr =
                                chip_info->clk_freq.cpsdvsr - 1;
        }
        status = verify_controller_parameters(pl022, chip_info);
        if (status) {
                dev_err(&spi->dev, "controller data is incorrect");
                goto err_config_params;
        }
        /* Now set controller state based on controller data */
        chip->xfer_type = chip_info->com_mode;
        chip->cs_control = chip_info->cs_control;

        if (chip_info->data_size <= 8) {
                dev_dbg(&spi->dev, "1 <= n <=8 bits per word\n");
                chip->n_bytes = 1;
                chip->read = READING_U8;
                chip->write = WRITING_U8;
        } else if (chip_info->data_size <= 16) {
                dev_dbg(&spi->dev, "9 <= n <= 16 bits per word\n");
                chip->n_bytes = 2;
                chip->read = READING_U16;
                chip->write = WRITING_U16;
        } else {
                if (pl022->vendor->max_bpw >= 32) {
                        dev_dbg(&spi->dev, "17 <= n <= 32 bits per word\n");
                        chip->n_bytes = 4;
                        chip->read = READING_U32;
                        chip->write = WRITING_U32;
                } else {
                        dev_err(&spi->dev,
                                "illegal data size for this controller!\n");
                        dev_err(&spi->dev,
                                "a standard pl022 can only handle "
                                "1 <= n <= 16 bit words\n");
                        goto err_config_params;
                }
        }

        /* Now Initialize all register settings required for this chip */
        chip->cr0 = 0;
        chip->cr1 = 0;
        chip->dmacr = 0;
        chip->cpsr = 0;
        if ((chip_info->com_mode == DMA_TRANSFER)
            && ((pl022->master_info)->enable_dma)) {
                chip->enable_dma = 1;
                dev_dbg(&spi->dev, "DMA mode set in controller state\n");
                status = process_dma_info(chip_info, chip);
                if (status < 0)
                        goto err_config_params;
                SSP_WRITE_BITS(chip->dmacr, SSP_DMA_ENABLED,
                               SSP_DMACR_MASK_RXDMAE, 0);
                SSP_WRITE_BITS(chip->dmacr, SSP_DMA_ENABLED,
                               SSP_DMACR_MASK_TXDMAE, 1);
        } else {
                chip->enable_dma = 0;
                dev_dbg(&spi->dev, "DMA mode NOT set in controller state\n");
                SSP_WRITE_BITS(chip->dmacr, SSP_DMA_DISABLED,
                               SSP_DMACR_MASK_RXDMAE, 0);
                SSP_WRITE_BITS(chip->dmacr, SSP_DMA_DISABLED,
                               SSP_DMACR_MASK_TXDMAE, 1);
        }

        chip->cpsr = chip_info->clk_freq.cpsdvsr;

        SSP_WRITE_BITS(chip->cr0, chip_info->data_size, SSP_CR0_MASK_DSS, 0);
        SSP_WRITE_BITS(chip->cr0, chip_info->duplex, SSP_CR0_MASK_HALFDUP, 5);
        SSP_WRITE_BITS(chip->cr0, chip_info->clk_pol, SSP_CR0_MASK_SPO, 6);
        SSP_WRITE_BITS(chip->cr0, chip_info->clk_phase, SSP_CR0_MASK_SPH, 7);
        SSP_WRITE_BITS(chip->cr0, chip_info->clk_freq.scr, SSP_CR0_MASK_SCR, 8);
        SSP_WRITE_BITS(chip->cr0, chip_info->ctrl_len, SSP_CR0_MASK_CSS, 16);
        SSP_WRITE_BITS(chip->cr0, chip_info->iface, SSP_CR0_MASK_FRF, 21);
        SSP_WRITE_BITS(chip->cr1, chip_info->lbm, SSP_CR1_MASK_LBM, 0);
        SSP_WRITE_BITS(chip->cr1, SSP_DISABLED, SSP_CR1_MASK_SSE, 1);
        SSP_WRITE_BITS(chip->cr1, chip_info->hierarchy, SSP_CR1_MASK_MS, 2);
        SSP_WRITE_BITS(chip->cr1, chip_info->slave_tx_disable, SSP_CR1_MASK_SOD, 3);
        SSP_WRITE_BITS(chip->cr1, chip_info->endian_rx, SSP_CR1_MASK_RENDN, 4);
        SSP_WRITE_BITS(chip->cr1, chip_info->endian_tx, SSP_CR1_MASK_TENDN, 5);
        SSP_WRITE_BITS(chip->cr1, chip_info->wait_state, SSP_CR1_MASK_MWAIT, 6);
        SSP_WRITE_BITS(chip->cr1, chip_info->rx_lev_trig, SSP_CR1_MASK_RXIFLSEL, 7);
        SSP_WRITE_BITS(chip->cr1, chip_info->tx_lev_trig, SSP_CR1_MASK_TXIFLSEL, 10);

        /* Save controller_state */
        spi_set_ctldata(spi, chip);
        return status;
 err_config_params:
 err_first_setup:
        kfree(chip);
        return status;
}

/**
 * pl022_cleanup - cleanup function registered to SPI master framework
 * @spi: spi device which is requesting cleanup
 *
 * This function is registered to the SPI framework for this SPI master
 * controller. It will free the runtime state of chip.
 */
static void pl022_cleanup(struct spi_device *spi)
{
        struct chip_data *chip = spi_get_ctldata(spi);

        spi_set_ctldata(spi, NULL);
        kfree(chip);
}


static int __init
pl022_probe(struct amba_device *adev, struct amba_id *id)
{
        struct device *dev = &adev->dev;
        struct pl022_ssp_controller *platform_info = adev->dev.platform_data;
        struct spi_master *master;
        struct pl022 *pl022 = NULL;     /*Data for this driver */
        int status = 0;

        dev_info(&adev->dev,
                 "ARM PL022 driver, device ID: 0x%08x\n", adev->periphid);
        if (platform_info == NULL) {
                dev_err(&adev->dev, "probe - no platform data supplied\n");
                status = -ENODEV;
                goto err_no_pdata;
        }

        /* Allocate master with space for data */
        master = spi_alloc_master(dev, sizeof(struct pl022));
        if (master == NULL) {
                dev_err(&adev->dev, "probe - cannot alloc SPI master\n");
                status = -ENOMEM;
                goto err_no_master;
        }

        pl022 = spi_master_get_devdata(master);
        pl022->master = master;
        pl022->master_info = platform_info;
        pl022->adev = adev;
        pl022->vendor = id->data;

        /*
         * Bus Number Which has been Assigned to this SSP controller
         * on this board
         */
        master->bus_num = platform_info->bus_id;
        master->num_chipselect = platform_info->num_chipselect;
        master->cleanup = pl022_cleanup;
        master->setup = pl022_setup;
        master->transfer = pl022_transfer;

        dev_dbg(&adev->dev, "BUSNO: %d\n", master->bus_num);

        status = amba_request_regions(adev, NULL);
        if (status)
                goto err_no_ioregion;

        pl022->virtbase = ioremap(adev->res.start, resource_size(&adev->res));
        if (pl022->virtbase == NULL) {
                status = -ENOMEM;
                goto err_no_ioremap;
        }
        printk(KERN_INFO "pl022: mapped registers from 0x%08x to %p\n",
               adev->res.start, pl022->virtbase);

        pl022->clk = clk_get(&adev->dev, NULL);
        if (IS_ERR(pl022->clk)) {
                status = PTR_ERR(pl022->clk);
                dev_err(&adev->dev, "could not retrieve SSP/SPI bus clock\n");
                goto err_no_clk;
        }

        /* Disable SSP */
        clk_enable(pl022->clk);
        writew((readw(SSP_CR1(pl022->virtbase)) & (~SSP_CR1_MASK_SSE)),
               SSP_CR1(pl022->virtbase));
        load_ssp_default_config(pl022);
        clk_disable(pl022->clk);

        status = request_irq(adev->irq[0], pl022_interrupt_handler, 0, "pl022",
                             pl022);
        if (status < 0) {
                dev_err(&adev->dev, "probe - cannot get IRQ (%d)\n", status);
                goto err_no_irq;
        }
        /* Initialize and start queue */
        status = init_queue(pl022);
        if (status != 0) {
                dev_err(&adev->dev, "probe - problem initializing queue\n");
                goto err_init_queue;
        }
        status = start_queue(pl022);
        if (status != 0) {
                dev_err(&adev->dev, "probe - problem starting queue\n");
                goto err_start_queue;
        }
        /* Register with the SPI framework */
        amba_set_drvdata(adev, pl022);
        status = spi_register_master(master);
        if (status != 0) {
                dev_err(&adev->dev,
                        "probe - problem registering spi master\n");
                goto err_spi_register;
        }
        dev_dbg(dev, "probe succeded\n");
        return 0;

 err_spi_register:
 err_start_queue:
 err_init_queue:
        destroy_queue(pl022);
        free_irq(adev->irq[0], pl022);
 err_no_irq:
        clk_put(pl022->clk);
 err_no_clk:
        iounmap(pl022->virtbase);
 err_no_ioremap:
        amba_release_regions(adev);
 err_no_ioregion:
        spi_master_put(master);
 err_no_master:
 err_no_pdata:
        return status;
}

static int __exit
pl022_remove(struct amba_device *adev)
{
        struct pl022 *pl022 = amba_get_drvdata(adev);
        int status = 0;
        if (!pl022)
                return 0;

        /* Remove the queue */
        status = destroy_queue(pl022);
        if (status != 0) {
                dev_err(&adev->dev,
                        "queue remove failed (%d)\n", status);
                return status;
        }
        load_ssp_default_config(pl022);
        free_irq(adev->irq[0], pl022);
        clk_disable(pl022->clk);
        clk_put(pl022->clk);
        iounmap(pl022->virtbase);
        amba_release_regions(adev);
        tasklet_disable(&pl022->pump_transfers);
        spi_unregister_master(pl022->master);
        spi_master_put(pl022->master);
        amba_set_drvdata(adev, NULL);
        dev_dbg(&adev->dev, "remove succeded\n");
        return 0;
}

#ifdef CONFIG_PM
static int pl022_suspend(struct amba_device *adev, pm_message_t state)
{
        struct pl022 *pl022 = amba_get_drvdata(adev);
        int status = 0;

        status = stop_queue(pl022);
        if (status) {
                dev_warn(&adev->dev, "suspend cannot stop queue\n");
                return status;
        }

        clk_enable(pl022->clk);
        load_ssp_default_config(pl022);
        clk_disable(pl022->clk);
        dev_dbg(&adev->dev, "suspended\n");
        return 0;
}

static int pl022_resume(struct amba_device *adev)
{
        struct pl022 *pl022 = amba_get_drvdata(adev);
        int status = 0;

        /* Start the queue running */
        status = start_queue(pl022);
        if (status)
                dev_err(&adev->dev, "problem starting queue (%d)\n", status);
        else
                dev_dbg(&adev->dev, "resumed\n");

        return status;
}
#else
#define pl022_suspend NULL
#define pl022_resume NULL
#endif  /* CONFIG_PM */

static struct vendor_data vendor_arm = {
        .fifodepth = 8,
        .max_bpw = 16,
        .unidir = false,
};


static struct vendor_data vendor_st = {
        .fifodepth = 32,
        .max_bpw = 32,
        .unidir = false,
};

static struct amba_id pl022_ids[] = {
        {
                /*
                 * ARM PL022 variant, this has a 16bit wide
                 * and 8 locations deep TX/RX FIFO
                 */
                .id     = 0x00041022,
                .mask   = 0x000fffff,
                .data   = &vendor_arm,
        },
        {
                /*
                 * ST Micro derivative, this has 32bit wide
                 * and 32 locations deep TX/RX FIFO
                 */
                .id     = 0x01080022,
                .mask   = 0xffffffff,
                .data   = &vendor_st,
        },
        { 0, 0 },
};

static struct amba_driver pl022_driver = {
        .drv = {
                .name   = "ssp-pl022",
        },
        .id_table       = pl022_ids,
        .probe          = pl022_probe,
        .remove         = __exit_p(pl022_remove),
        .suspend        = pl022_suspend,
        .resume         = pl022_resume,
};


static int __init pl022_init(void)
{
        return amba_driver_register(&pl022_driver);
}

module_init(pl022_init);

static void __exit pl022_exit(void)
{
        amba_driver_unregister(&pl022_driver);
}

module_exit(pl022_exit);

MODULE_AUTHOR("Linus Walleij <linus.walleij@stericsson.com>");
MODULE_DESCRIPTION("PL022 SSP Controller Driver");
MODULE_LICENSE("GPL");