/*
 *  i2c_adap_pxa.c
 *
 *  I2C adapter for the PXA I2C bus access.
 *
 *  Copyright (C) 2002 Intrinsyc Software Inc.
 *  Copyright (C) 2004-2005 Deep Blue Solutions Ltd.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2 as
 *  published by the Free Software Foundation.
 *
 *  History:
 *    Apr 2002: Initial version [CS]
 *    Jun 2002: Properly seperated algo/adap [FB]
 *    Jan 2003: Fixed several bugs concerning interrupt handling [Kai-Uwe Bloem]
 *    Jan 2003: added limited signal handling [Kai-Uwe Bloem]
 *    Sep 2004: Major rework to ensure efficient bus handling [RMK]
 *    Dec 2004: Added support for PXA27x and slave device probing [Liam Girdwood]
 *    Feb 2005: Rework slave mode handling [RMK]
 */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/i2c-id.h>
#include <linux/init.h>
#include <linux/time.h>
#include <linux/sched.h>
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/i2c-pxa.h>
#include <linux/platform_device.h>
#include <linux/err.h>
#include <linux/clk.h>

#include <asm/hardware.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <asm/arch/i2c.h>
#include <asm/arch/pxa-regs.h>

struct pxa_i2c {
        spinlock_t              lock;
        wait_queue_head_t       wait;
        struct i2c_msg          *msg;
        unsigned int            msg_num;
        unsigned int            msg_idx;
        unsigned int            msg_ptr;
        unsigned int            slave_addr;

        struct i2c_adapter      adap;
        struct clk              *clk;
#ifdef CONFIG_I2C_PXA_SLAVE
        struct i2c_slave_client *slave;
#endif

        unsigned int            irqlogidx;
        u32                     isrlog[32];
        u32                     icrlog[32];

        void __iomem            *reg_base;

        unsigned long           iobase;
        unsigned long           iosize;

        int                     irq;
};

#define _IBMR(i2c)      ((i2c)->reg_base + 0)
#define _IDBR(i2c)      ((i2c)->reg_base + 8)
#define _ICR(i2c)       ((i2c)->reg_base + 0x10)
#define _ISR(i2c)       ((i2c)->reg_base + 0x18)
#define _ISAR(i2c)      ((i2c)->reg_base + 0x20)

/*
 * I2C Slave mode address
 */
#define I2C_PXA_SLAVE_ADDR      0x1

#ifdef DEBUG

struct bits {
        u32     mask;
        const char *set;
        const char *unset;
};
#define PXA_BIT(m, s, u)        { .mask = m, .set = s, .unset = u }

static inline void
decode_bits(const char *prefix, const struct bits *bits, int num, u32 val)
{
        printk("%s %08x: ", prefix, val);
        while (num--) {
                const char *str = val & bits->mask ? bits->set : bits->unset;
                if (str)
                        printk("%s ", str);
                bits++;
        }
}

static const struct bits isr_bits[] = {
        PXA_BIT(ISR_RWM,        "RX",           "TX"),
        PXA_BIT(ISR_ACKNAK,     "NAK",          "ACK"),
        PXA_BIT(ISR_UB,         "Bsy",          "Rdy"),
        PXA_BIT(ISR_IBB,        "BusBsy",       "BusRdy"),
        PXA_BIT(ISR_SSD,        "SlaveStop",    NULL),
        PXA_BIT(ISR_ALD,        "ALD",          NULL),
        PXA_BIT(ISR_ITE,        "TxEmpty",      NULL),
        PXA_BIT(ISR_IRF,        "RxFull",       NULL),
        PXA_BIT(ISR_GCAD,       "GenCall",      NULL),
        PXA_BIT(ISR_SAD,        "SlaveAddr",    NULL),
        PXA_BIT(ISR_BED,        "BusErr",       NULL),
};

static void decode_ISR(unsigned int val)
{
        decode_bits(KERN_DEBUG "ISR", isr_bits, ARRAY_SIZE(isr_bits), val);
        printk("\n");
}

static const struct bits icr_bits[] = {
        PXA_BIT(ICR_START,  "START",    NULL),
        PXA_BIT(ICR_STOP,   "STOP",     NULL),
        PXA_BIT(ICR_ACKNAK, "ACKNAK",   NULL),
        PXA_BIT(ICR_TB,     "TB",       NULL),
        PXA_BIT(ICR_MA,     "MA",       NULL),
        PXA_BIT(ICR_SCLE,   "SCLE",     "scle"),
        PXA_BIT(ICR_IUE,    "IUE",      "iue"),
        PXA_BIT(ICR_GCD,    "GCD",      NULL),
        PXA_BIT(ICR_ITEIE,  "ITEIE",    NULL),
        PXA_BIT(ICR_IRFIE,  "IRFIE",    NULL),
        PXA_BIT(ICR_BEIE,   "BEIE",     NULL),
        PXA_BIT(ICR_SSDIE,  "SSDIE",    NULL),
        PXA_BIT(ICR_ALDIE,  "ALDIE",    NULL),
        PXA_BIT(ICR_SADIE,  "SADIE",    NULL),
        PXA_BIT(ICR_UR,     "UR",               "ur"),
};

static void decode_ICR(unsigned int val)
{
        decode_bits(KERN_DEBUG "ICR", icr_bits, ARRAY_SIZE(icr_bits), val);
        printk("\n");
}

static unsigned int i2c_debug = DEBUG;

static void i2c_pxa_show_state(struct pxa_i2c *i2c, int lno, const char *fname)
{
        dev_dbg(&i2c->adap.dev, "state:%s:%d: ISR=%08x, ICR=%08x, IBMR=%02x\n", fname, lno,
                readl(_ISR(i2c)), readl(_ICR(i2c)), readl(_IBMR(i2c)));
}

#define show_state(i2c) i2c_pxa_show_state(i2c, __LINE__, __FUNCTION__)
#else
#define i2c_debug       0

#define show_state(i2c) do { } while (0)
#define decode_ISR(val) do { } while (0)
#define decode_ICR(val) do { } while (0)
#endif

#define eedbg(lvl, x...) do { if ((lvl) < 1) { printk(KERN_DEBUG "" x); } } while(0)

static void i2c_pxa_master_complete(struct pxa_i2c *i2c, int ret);

static void i2c_pxa_scream_blue_murder(struct pxa_i2c *i2c, const char *why)
{
        unsigned int i;
        printk("i2c: error: %s\n", why);
        printk("i2c: msg_num: %d msg_idx: %d msg_ptr: %d\n",
                i2c->msg_num, i2c->msg_idx, i2c->msg_ptr);
        printk("i2c: ICR: %08x ISR: %08x\n"
               "i2c: log: ", readl(_ICR(i2c)), readl(_ISR(i2c)));
        for (i = 0; i < i2c->irqlogidx; i++)
                printk("[%08x:%08x] ", i2c->isrlog[i], i2c->icrlog[i]);
        printk("\n");
}

static inline int i2c_pxa_is_slavemode(struct pxa_i2c *i2c)
{
        return !(readl(_ICR(i2c)) & ICR_SCLE);
}

static void i2c_pxa_abort(struct pxa_i2c *i2c)
{
        unsigned long timeout = jiffies + HZ/4;

        if (i2c_pxa_is_slavemode(i2c)) {
                dev_dbg(&i2c->adap.dev, "%s: called in slave mode\n", __func__);
                return;
        }

        while (time_before(jiffies, timeout) && (readl(_IBMR(i2c)) & 0x1) == 0) {
                unsigned long icr = readl(_ICR(i2c));

                icr &= ~ICR_START;
                icr |= ICR_ACKNAK | ICR_STOP | ICR_TB;

                writel(icr, _ICR(i2c));

                show_state(i2c);

                msleep(1);
        }

        writel(readl(_ICR(i2c)) & ~(ICR_MA | ICR_START | ICR_STOP),
               _ICR(i2c));
}

static int i2c_pxa_wait_bus_not_busy(struct pxa_i2c *i2c)
{
        int timeout = DEF_TIMEOUT;

        while (timeout-- && readl(_ISR(i2c)) & (ISR_IBB | ISR_UB)) {
                if ((readl(_ISR(i2c)) & ISR_SAD) != 0)
                        timeout += 4;

                msleep(2);
                show_state(i2c);
        }

        if (timeout <= 0)
                show_state(i2c);

        return timeout <= 0 ? I2C_RETRY : 0;
}

static int i2c_pxa_wait_master(struct pxa_i2c *i2c)
{
        unsigned long timeout = jiffies + HZ*4;

        while (time_before(jiffies, timeout)) {
                if (i2c_debug > 1)
                        dev_dbg(&i2c->adap.dev, "%s: %ld: ISR=%08x, ICR=%08x, IBMR=%02x\n",
                                __func__, (long)jiffies, readl(_ISR(i2c)), readl(_ICR(i2c)), readl(_IBMR(i2c)));

                if (readl(_ISR(i2c)) & ISR_SAD) {
                        if (i2c_debug > 0)
                                dev_dbg(&i2c->adap.dev, "%s: Slave detected\n", __func__);
                        goto out;
                }

                /* wait for unit and bus being not busy, and we also do a
                 * quick check of the i2c lines themselves to ensure they've
                 * gone high...
                 */
                if ((readl(_ISR(i2c)) & (ISR_UB | ISR_IBB)) == 0 && readl(_IBMR(i2c)) == 3) {
                        if (i2c_debug > 0)
                                dev_dbg(&i2c->adap.dev, "%s: done\n", __func__);
                        return 1;
                }

                msleep(1);
        }

        if (i2c_debug > 0)
                dev_dbg(&i2c->adap.dev, "%s: did not free\n", __func__);
 out:
        return 0;
}

static int i2c_pxa_set_master(struct pxa_i2c *i2c)
{
        if (i2c_debug)
                dev_dbg(&i2c->adap.dev, "setting to bus master\n");

        if ((readl(_ISR(i2c)) & (ISR_UB | ISR_IBB)) != 0) {
                dev_dbg(&i2c->adap.dev, "%s: unit is busy\n", __func__);
                if (!i2c_pxa_wait_master(i2c)) {
                        dev_dbg(&i2c->adap.dev, "%s: error: unit busy\n", __func__);
                        return I2C_RETRY;
                }
        }

        writel(readl(_ICR(i2c)) | ICR_SCLE, _ICR(i2c));
        return 0;
}

#ifdef CONFIG_I2C_PXA_SLAVE
static int i2c_pxa_wait_slave(struct pxa_i2c *i2c)
{
        unsigned long timeout = jiffies + HZ*1;

        /* wait for stop */

        show_state(i2c);

        while (time_before(jiffies, timeout)) {
                if (i2c_debug > 1)
                        dev_dbg(&i2c->adap.dev, "%s: %ld: ISR=%08x, ICR=%08x, IBMR=%02x\n",
                                __func__, (long)jiffies, readl(_ISR(i2c)), readl(_ICR(i2c)), readl(_IBMR(i2c)));

                if ((readl(_ISR(i2c)) & (ISR_UB|ISR_IBB)) == 0 ||
                    (readl(_ISR(i2c)) & ISR_SAD) != 0 ||
                    (readl(_ICR(i2c)) & ICR_SCLE) == 0) {
                        if (i2c_debug > 1)
                                dev_dbg(&i2c->adap.dev, "%s: done\n", __func__);
                        return 1;
                }

                msleep(1);
        }

        if (i2c_debug > 0)
                dev_dbg(&i2c->adap.dev, "%s: did not free\n", __func__);
        return 0;
}

/*
 * clear the hold on the bus, and take of anything else
 * that has been configured
 */
static void i2c_pxa_set_slave(struct pxa_i2c *i2c, int errcode)
{
        show_state(i2c);

        if (errcode < 0) {
                udelay(100);   /* simple delay */
        } else {
                /* we need to wait for the stop condition to end */

                /* if we where in stop, then clear... */
                if (readl(_ICR(i2c)) & ICR_STOP) {
                        udelay(100);
                        writel(readl(_ICR(i2c)) & ~ICR_STOP, _ICR(i2c));
                }

                if (!i2c_pxa_wait_slave(i2c)) {
                        dev_err(&i2c->adap.dev, "%s: wait timedout\n",
                                __func__);
                        return;
                }
        }

        writel(readl(_ICR(i2c)) & ~(ICR_STOP|ICR_ACKNAK|ICR_MA), _ICR(i2c));
        writel(readl(_ICR(i2c)) & ~ICR_SCLE, _ICR(i2c));

        if (i2c_debug) {
                dev_dbg(&i2c->adap.dev, "ICR now %08x, ISR %08x\n", readl(_ICR(i2c)), readl(_ISR(i2c)));
                decode_ICR(readl(_ICR(i2c)));
        }
}
#else
#define i2c_pxa_set_slave(i2c, err)     do { } while (0)
#endif

static void i2c_pxa_reset(struct pxa_i2c *i2c)
{
        pr_debug("Resetting I2C Controller Unit\n");

        /* abort any transfer currently under way */
        i2c_pxa_abort(i2c);

        /* reset according to 9.8 */
        writel(ICR_UR, _ICR(i2c));
        writel(I2C_ISR_INIT, _ISR(i2c));
        writel(readl(_ICR(i2c)) & ~ICR_UR, _ICR(i2c));

        writel(i2c->slave_addr, _ISAR(i2c));

        /* set control register values */
        writel(I2C_ICR_INIT, _ICR(i2c));

#ifdef CONFIG_I2C_PXA_SLAVE
        dev_info(&i2c->adap.dev, "Enabling slave mode\n");
        writel(readl(_ICR(i2c)) | ICR_SADIE | ICR_ALDIE | ICR_SSDIE, _ICR(i2c));
#endif

        i2c_pxa_set_slave(i2c, 0);

        /* enable unit */
        writel(readl(_ICR(i2c)) | ICR_IUE, _ICR(i2c));
        udelay(100);
}


#ifdef CONFIG_I2C_PXA_SLAVE
/*
 * PXA I2C Slave mode
 */

static void i2c_pxa_slave_txempty(struct pxa_i2c *i2c, u32 isr)
{
        if (isr & ISR_BED) {
                /* what should we do here? */
        } else {
                int ret = 0;

                if (i2c->slave != NULL)
                        ret = i2c->slave->read(i2c->slave->data);

                writel(ret, _IDBR(i2c));
                writel(readl(_ICR(i2c)) | ICR_TB, _ICR(i2c));   /* allow next byte */
        }
}

static void i2c_pxa_slave_rxfull(struct pxa_i2c *i2c, u32 isr)
{
        unsigned int byte = readl(_IDBR(i2c));

        if (i2c->slave != NULL)
                i2c->slave->write(i2c->slave->data, byte);

        writel(readl(_ICR(i2c)) | ICR_TB, _ICR(i2c));
}

static void i2c_pxa_slave_start(struct pxa_i2c *i2c, u32 isr)
{
        int timeout;

        if (i2c_debug > 0)
                dev_dbg(&i2c->adap.dev, "SAD, mode is slave-%cx\n",
                       (isr & ISR_RWM) ? 'r' : 't');

        if (i2c->slave != NULL)
                i2c->slave->event(i2c->slave->data,
                                 (isr & ISR_RWM) ? I2C_SLAVE_EVENT_START_READ : I2C_SLAVE_EVENT_START_WRITE);

        /*
         * slave could interrupt in the middle of us generating a
         * start condition... if this happens, we'd better back off
         * and stop holding the poor thing up
         */
        writel(readl(_ICR(i2c)) & ~(ICR_START|ICR_STOP), _ICR(i2c));
        writel(readl(_ICR(i2c)) | ICR_TB, _ICR(i2c));

        timeout = 0x10000;

        while (1) {
                if ((readl(_IBMR(i2c)) & 2) == 2)
                        break;

                timeout--;

                if (timeout <= 0) {
                        dev_err(&i2c->adap.dev, "timeout waiting for SCL high\n");
                        break;
                }
        }

        writel(readl(_ICR(i2c)) & ~ICR_SCLE, _ICR(i2c));
}

static void i2c_pxa_slave_stop(struct pxa_i2c *i2c)
{
        if (i2c_debug > 2)
                dev_dbg(&i2c->adap.dev, "ISR: SSD (Slave Stop)\n");

        if (i2c->slave != NULL)
                i2c->slave->event(i2c->slave->data, I2C_SLAVE_EVENT_STOP);

        if (i2c_debug > 2)
                dev_dbg(&i2c->adap.dev, "ISR: SSD (Slave Stop) acked\n");

        /*
         * If we have a master-mode message waiting,
         * kick it off now that the slave has completed.
         */
        if (i2c->msg)
                i2c_pxa_master_complete(i2c, I2C_RETRY);
}
#else
static void i2c_pxa_slave_txempty(struct pxa_i2c *i2c, u32 isr)
{
        if (isr & ISR_BED) {
                /* what should we do here? */
        } else {
                writel(0, _IDBR(i2c));
                writel(readl(_ICR(i2c)) | ICR_TB, _ICR(i2c));
        }
}

static void i2c_pxa_slave_rxfull(struct pxa_i2c *i2c, u32 isr)
{
        writel(readl(_ICR(i2c)) | ICR_TB | ICR_ACKNAK, _ICR(i2c));
}

static void i2c_pxa_slave_start(struct pxa_i2c *i2c, u32 isr)
{
        int timeout;

        /*
         * slave could interrupt in the middle of us generating a
         * start condition... if this happens, we'd better back off
         * and stop holding the poor thing up
         */
        writel(readl(_ICR(i2c)) & ~(ICR_START|ICR_STOP), _ICR(i2c));
        writel(readl(_ICR(i2c)) | ICR_TB | ICR_ACKNAK, _ICR(i2c));

        timeout = 0x10000;

        while (1) {
                if ((readl(_IBMR(i2c)) & 2) == 2)
                        break;

                timeout--;

                if (timeout <= 0) {
                        dev_err(&i2c->adap.dev, "timeout waiting for SCL high\n");
                        break;
                }
        }

        writel(readl(_ICR(i2c)) & ~ICR_SCLE, _ICR(i2c));
}

static void i2c_pxa_slave_stop(struct pxa_i2c *i2c)
{
        if (i2c->msg)
                i2c_pxa_master_complete(i2c, I2C_RETRY);
}
#endif

/*
 * PXA I2C Master mode
 */

static inline unsigned int i2c_pxa_addr_byte(struct i2c_msg *msg)
{
        unsigned int addr = (msg->addr & 0x7f) << 1;

        if (msg->flags & I2C_M_RD)
                addr |= 1;

        return addr;
}

static inline void i2c_pxa_start_message(struct pxa_i2c *i2c)
{
        u32 icr;

        /*
         * Step 1: target slave address into IDBR
         */
        writel(i2c_pxa_addr_byte(i2c->msg), _IDBR(i2c));

        /*
         * Step 2: initiate the write.
         */
        icr = readl(_ICR(i2c)) & ~(ICR_STOP | ICR_ALDIE);
        writel(icr | ICR_START | ICR_TB, _ICR(i2c));
}

static inline void i2c_pxa_stop_message(struct pxa_i2c *i2c)
{
        u32 icr;

        /*
         * Clear the STOP and ACK flags
         */
        icr = readl(_ICR(i2c));
        icr &= ~(ICR_STOP | ICR_ACKNAK);
        writel(icr, _ICR(i2c));
}

/*
 * We are protected by the adapter bus mutex.
 */
static int i2c_pxa_do_xfer(struct pxa_i2c *i2c, struct i2c_msg *msg, int num)
{
        long timeout;
        int ret;

        /*
         * Wait for the bus to become free.
         */
        ret = i2c_pxa_wait_bus_not_busy(i2c);
        if (ret) {
                dev_err(&i2c->adap.dev, "i2c_pxa: timeout waiting for bus free\n");
                goto out;
        }

        /*
         * Set master mode.
         */
        ret = i2c_pxa_set_master(i2c);
        if (ret) {
                dev_err(&i2c->adap.dev, "i2c_pxa_set_master: error %d\n", ret);
                goto out;
        }

        spin_lock_irq(&i2c->lock);

        i2c->msg = msg;
        i2c->msg_num = num;
        i2c->msg_idx = 0;
        i2c->msg_ptr = 0;
        i2c->irqlogidx = 0;

        i2c_pxa_start_message(i2c);

        spin_unlock_irq(&i2c->lock);

        /*
         * The rest of the processing occurs in the interrupt handler.
         */
        timeout = wait_event_timeout(i2c->wait, i2c->msg_num == 0, HZ * 5);
        i2c_pxa_stop_message(i2c);

        /*
         * We place the return code in i2c->msg_idx.
         */
        ret = i2c->msg_idx;

        if (timeout == 0)
                i2c_pxa_scream_blue_murder(i2c, "timeout");

 out:
        return ret;
}

/*
 * i2c_pxa_master_complete - complete the message and wake up.
 */
static void i2c_pxa_master_complete(struct pxa_i2c *i2c, int ret)
{
        i2c->msg_ptr = 0;
        i2c->msg = NULL;
        i2c->msg_idx ++;
        i2c->msg_num = 0;
        if (ret)
                i2c->msg_idx = ret;
        wake_up(&i2c->wait);
}

static void i2c_pxa_irq_txempty(struct pxa_i2c *i2c, u32 isr)
{
        u32 icr = readl(_ICR(i2c)) & ~(ICR_START|ICR_STOP|ICR_ACKNAK|ICR_TB);

 again:
        /*
         * If ISR_ALD is set, we lost arbitration.
         */
        if (isr & ISR_ALD) {
                /*
                 * Do we need to do anything here?  The PXA docs
                 * are vague about what happens.
                 */
                i2c_pxa_scream_blue_murder(i2c, "ALD set");

                /*
                 * We ignore this error.  We seem to see spurious ALDs
                 * for seemingly no reason.  If we handle them as I think
                 * they should, we end up causing an I2C error, which
                 * is painful for some systems.
                 */
                return; /* ignore */
        }

        if (isr & ISR_BED) {
                int ret = BUS_ERROR;

                /*
                 * I2C bus error - either the device NAK'd us, or
                 * something more serious happened.  If we were NAK'd
                 * on the initial address phase, we can retry.
                 */
                if (isr & ISR_ACKNAK) {
                        if (i2c->msg_ptr == 0 && i2c->msg_idx == 0)
                                ret = I2C_RETRY;
                        else
                                ret = XFER_NAKED;
                }
                i2c_pxa_master_complete(i2c, ret);
        } else if (isr & ISR_RWM) {
                /*
                 * Read mode.  We have just sent the address byte, and
                 * now we must initiate the transfer.
                 */
                if (i2c->msg_ptr == i2c->msg->len - 1 &&
                    i2c->msg_idx == i2c->msg_num - 1)
                        icr |= ICR_STOP | ICR_ACKNAK;

                icr |= ICR_ALDIE | ICR_TB;
        } else if (i2c->msg_ptr < i2c->msg->len) {
                /*
                 * Write mode.  Write the next data byte.
                 */
                writel(i2c->msg->buf[i2c->msg_ptr++], _IDBR(i2c));

                icr |= ICR_ALDIE | ICR_TB;

                /*
                 * If this is the last byte of the last message, send
                 * a STOP.
                 */
                if (i2c->msg_ptr == i2c->msg->len &&
                    i2c->msg_idx == i2c->msg_num - 1)
                        icr |= ICR_STOP;
        } else if (i2c->msg_idx < i2c->msg_num - 1) {
                /*
                 * Next segment of the message.
                 */
                i2c->msg_ptr = 0;
                i2c->msg_idx ++;
                i2c->msg++;

                /*
                 * If we aren't doing a repeated start and address,
                 * go back and try to send the next byte.  Note that
                 * we do not support switching the R/W direction here.
                 */
                if (i2c->msg->flags & I2C_M_NOSTART)
                        goto again;

                /*
                 * Write the next address.
                 */
                writel(i2c_pxa_addr_byte(i2c->msg), _IDBR(i2c));

                /*
                 * And trigger a repeated start, and send the byte.
                 */
                icr &= ~ICR_ALDIE;
                icr |= ICR_START | ICR_TB;
        } else {
                if (i2c->msg->len == 0) {
                        /*
                         * Device probes have a message length of zero
                         * and need the bus to be reset before it can
                         * be used again.
                         */
                        i2c_pxa_reset(i2c);
                }
                i2c_pxa_master_complete(i2c, 0);
        }

        i2c->icrlog[i2c->irqlogidx-1] = icr;

        writel(icr, _ICR(i2c));
        show_state(i2c);
}

static void i2c_pxa_irq_rxfull(struct pxa_i2c *i2c, u32 isr)
{
        u32 icr = readl(_ICR(i2c)) & ~(ICR_START|ICR_STOP|ICR_ACKNAK|ICR_TB);

        /*
         * Read the byte.
         */
        i2c->msg->buf[i2c->msg_ptr++] = readl(_IDBR(i2c));

        if (i2c->msg_ptr < i2c->msg->len) {
                /*
                 * If this is the last byte of the last
                 * message, send a STOP.
                 */
                if (i2c->msg_ptr == i2c->msg->len - 1)
                        icr |= ICR_STOP | ICR_ACKNAK;

                icr |= ICR_ALDIE | ICR_TB;
        } else {
                i2c_pxa_master_complete(i2c, 0);
        }

        i2c->icrlog[i2c->irqlogidx-1] = icr;

        writel(icr, _ICR(i2c));
}

static irqreturn_t i2c_pxa_handler(int this_irq, void *dev_id)
{
        struct pxa_i2c *i2c = dev_id;
        u32 isr = readl(_ISR(i2c));

        if (i2c_debug > 2 && 0) {
                dev_dbg(&i2c->adap.dev, "%s: ISR=%08x, ICR=%08x, IBMR=%02x\n",
                        __func__, isr, readl(_ICR(i2c)), readl(_IBMR(i2c)));
                decode_ISR(isr);
        }

        if (i2c->irqlogidx < ARRAY_SIZE(i2c->isrlog))
                i2c->isrlog[i2c->irqlogidx++] = isr;

        show_state(i2c);

        /*
         * Always clear all pending IRQs.
         */
        writel(isr & (ISR_SSD|ISR_ALD|ISR_ITE|ISR_IRF|ISR_SAD|ISR_BED), _ISR(i2c));

        if (isr & ISR_SAD)
                i2c_pxa_slave_start(i2c, isr);
        if (isr & ISR_SSD)
                i2c_pxa_slave_stop(i2c);

        if (i2c_pxa_is_slavemode(i2c)) {
                if (isr & ISR_ITE)
                        i2c_pxa_slave_txempty(i2c, isr);
                if (isr & ISR_IRF)
                        i2c_pxa_slave_rxfull(i2c, isr);
        } else if (i2c->msg) {
                if (isr & ISR_ITE)
                        i2c_pxa_irq_txempty(i2c, isr);
                if (isr & ISR_IRF)
                        i2c_pxa_irq_rxfull(i2c, isr);
        } else {
                i2c_pxa_scream_blue_murder(i2c, "spurious irq");
        }

        return IRQ_HANDLED;
}


static int i2c_pxa_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
{
        struct pxa_i2c *i2c = adap->algo_data;
        int ret, i;

        /* If the I2C controller is disabled we need to reset it (probably due
           to a suspend/resume destroying state). We do this here as we can then
           avoid worrying about resuming the controller before its users. */
        if (!(readl(_ICR(i2c)) & ICR_IUE))
                i2c_pxa_reset(i2c);

        for (i = adap->retries; i >= 0; i--) {
                ret = i2c_pxa_do_xfer(i2c, msgs, num);
                if (ret != I2C_RETRY)
                        goto out;

                if (i2c_debug)
                        dev_dbg(&adap->dev, "Retrying transmission\n");
                udelay(100);
        }
        i2c_pxa_scream_blue_murder(i2c, "exhausted retries");
        ret = -EREMOTEIO;
 out:
        i2c_pxa_set_slave(i2c, ret);
        return ret;
}

static u32 i2c_pxa_functionality(struct i2c_adapter *adap)
{
        return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
}

static const struct i2c_algorithm i2c_pxa_algorithm = {
        .master_xfer    = i2c_pxa_xfer,
        .functionality  = i2c_pxa_functionality,
};

#define res_len(r)              ((r)->end - (r)->start + 1)
static int i2c_pxa_probe(struct platform_device *dev)
{
        struct pxa_i2c *i2c;
        struct resource *res;
        struct i2c_pxa_platform_data *plat = dev->dev.platform_data;
        int ret;
        int irq;

        res = platform_get_resource(dev, IORESOURCE_MEM, 0);
        irq = platform_get_irq(dev, 0);
        if (res == NULL || irq < 0)
                return -ENODEV;

        if (!request_mem_region(res->start, res_len(res), res->name))
                return -ENOMEM;

        i2c = kzalloc(sizeof(struct pxa_i2c), GFP_KERNEL);
        if (!i2c) {
                ret = -ENOMEM;
                goto emalloc;
        }

        i2c->adap.owner   = THIS_MODULE;
        i2c->adap.algo    = &i2c_pxa_algorithm;
        i2c->adap.retries = 5;

        spin_lock_init(&i2c->lock);
        init_waitqueue_head(&i2c->wait);

        sprintf(i2c->adap.name, "pxa_i2c-i2c.%u", dev->id);

        i2c->clk = clk_get(&dev->dev, "I2CCLK");
        if (IS_ERR(i2c->clk)) {
                ret = PTR_ERR(i2c->clk);
                goto eclk;
        }

        i2c->reg_base = ioremap(res->start, res_len(res));
        if (!i2c->reg_base) {
                ret = -EIO;
                goto eremap;
        }

        i2c->iobase = res->start;
        i2c->iosize = res_len(res);

        i2c->irq = irq;

        i2c->slave_addr = I2C_PXA_SLAVE_ADDR;

#ifdef CONFIG_I2C_PXA_SLAVE
        if (plat) {
                i2c->slave_addr = plat->slave_addr;
                i2c->slave = plat->slave;
        }
#endif

        clk_enable(i2c->clk);
#ifdef CONFIG_PXA27x
        switch (dev->id) {
        case 0:
                pxa_gpio_mode(GPIO117_I2CSCL_MD);
                pxa_gpio_mode(GPIO118_I2CSDA_MD);
                break;
        case 1:
                local_irq_disable();
                PCFR |= PCFR_PI2CEN;
                local_irq_enable();
        }
#endif

        ret = request_irq(irq, i2c_pxa_handler, IRQF_DISABLED,
                          i2c->adap.name, i2c);
        if (ret)
                goto ereqirq;


        i2c_pxa_reset(i2c);

        i2c->adap.algo_data = i2c;
        i2c->adap.dev.parent = &dev->dev;

        if (plat) {
                i2c->adap.class = plat->class;
        }

        /*
         * If "dev->id" is negative we consider it as zero.
         * The reason to do so is to avoid sysfs names that only make
         * sense when there are multiple adapters.
         */
        i2c->adap.nr = dev->id != -1 ? dev->id : 0;

        ret = i2c_add_numbered_adapter(&i2c->adap);
        if (ret < 0) {
                printk(KERN_INFO "I2C: Failed to add bus\n");
                goto eadapt;
        }

        platform_set_drvdata(dev, i2c);

#ifdef CONFIG_I2C_PXA_SLAVE
        printk(KERN_INFO "I2C: %s: PXA I2C adapter, slave address %d\n",
               i2c->adap.dev.bus_id, i2c->slave_addr);
#else
        printk(KERN_INFO "I2C: %s: PXA I2C adapter\n",
               i2c->adap.dev.bus_id);
#endif
        return 0;

eadapt:
        free_irq(irq, i2c);
ereqirq:
        clk_disable(i2c->clk);

#ifdef CONFIG_PXA27x
        if (dev->id == 1) {
                local_irq_disable();
                PCFR &= ~PCFR_PI2CEN;
                local_irq_enable();
        }
#endif
eremap:
        clk_put(i2c->clk);
eclk:
        kfree(i2c);
emalloc:
        release_mem_region(res->start, res_len(res));
        return ret;
}

static int i2c_pxa_remove(struct platform_device *dev)
{
        struct pxa_i2c *i2c = platform_get_drvdata(dev);

        platform_set_drvdata(dev, NULL);

        i2c_del_adapter(&i2c->adap);
        free_irq(i2c->irq, i2c);

        clk_disable(i2c->clk);
        clk_put(i2c->clk);

#ifdef CONFIG_PXA27x
        if (dev->id == 1) {
                local_irq_disable();
                PCFR &= ~PCFR_PI2CEN;
                local_irq_enable();
        }
#endif

        release_mem_region(i2c->iobase, i2c->iosize);
        kfree(i2c);

        return 0;
}

static struct platform_driver i2c_pxa_driver = {
        .probe          = i2c_pxa_probe,
        .remove         = i2c_pxa_remove,
        .driver         = {
                .name   = "pxa2xx-i2c",
        },
};

static int __init i2c_adap_pxa_init(void)
{
        return platform_driver_register(&i2c_pxa_driver);
}

static void i2c_adap_pxa_exit(void)
{
        return platform_driver_unregister(&i2c_pxa_driver);
}

MODULE_LICENSE("GPL");

module_init(i2c_adap_pxa_init);
module_exit(i2c_adap_pxa_exit);