[PATCH] I2C: Add PXA I2C driver

Add support for the I2C PXA driver.

Signed-off-by: Russell King <rmk@arm.linux.org.uk>

1 files changed, 1031 insertions, 0 deletions

diff --git a/drivers/i2c/busses/i2c-pxa.c b/drivers/i2c/busses/i2c-pxa.c
new file mode 100644
index 000000000000..a72d28365297
--- /dev/null
+++ b/drivers/i2c/busses/i2c-pxa.c
@@ -0,0 +1,1031 @@
+/*
+ *  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 <asm/hardware.h>
+#include <asm/irq.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;
+#ifdef CONFIG_I2C_PXA_SLAVE
+        struct i2c_slave_client *slave;
+#endif
+
+        unsigned int            irqlogidx;
+        u32                     isrlog[32];
+        u32                     icrlog[32];
+};
+
+/*
+ * I2C Slave mode address
+ */
+#define I2C_PXA_SLAVE_ADDR      0x1
+
+/*
+ * Set this to zero to remove all debug statements via dead code elimination.
+ */
+#undef DEBUG
+
+#if 0
+#define DBGLVL KERN_INFO
+#else
+#define DBGLVL KERN_DEBUG
+#endif
+
+#ifdef DEBUG
+
+struct bits {
+        u32     mask;
+        const char *set;
+        const char *unset;
+};
+#define 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[] = {
+        BIT(ISR_RWM,    "RX",           "TX"),
+        BIT(ISR_ACKNAK, "NAK",          "ACK"),
+        BIT(ISR_UB,     "Bsy",          "Rdy"),
+        BIT(ISR_IBB,    "BusBsy",       "BusRdy"),
+        BIT(ISR_SSD,    "SlaveStop",    NULL),
+        BIT(ISR_ALD,    "ALD",          NULL),
+        BIT(ISR_ITE,    "TxEmpty",      NULL),
+        BIT(ISR_IRF,    "RxFull",       NULL),
+        BIT(ISR_GCAD,   "GenCall",      NULL),
+        BIT(ISR_SAD,    "SlaveAddr",    NULL),
+        BIT(ISR_BED,    "BusErr",       NULL),
+};
+
+static void decode_ISR(unsigned int val)
+{
+        decode_bits(DBGLVL "ISR", isr_bits, ARRAY_SIZE(isr_bits), val);
+        printk("\n");
+}
+
+static const struct bits icr_bits[] = {
+        BIT(ICR_START,  "START",        NULL),
+        BIT(ICR_STOP,   "STOP",         NULL),
+        BIT(ICR_ACKNAK, "ACKNAK",       NULL),
+        BIT(ICR_TB,     "TB",           NULL),
+        BIT(ICR_MA,     "MA",           NULL),
+        BIT(ICR_SCLE,   "SCLE",         "scle"),
+        BIT(ICR_IUE,    "IUE",          "iue"),
+        BIT(ICR_GCD,    "GCD",          NULL),
+        BIT(ICR_ITEIE,  "ITEIE",        NULL),
+        BIT(ICR_IRFIE,  "IRFIE",        NULL),
+        BIT(ICR_BEIE,   "BEIE",         NULL),
+        BIT(ICR_SSDIE,  "SSDIE",        NULL),
+        BIT(ICR_ALDIE,  "ALDIE",        NULL),
+        BIT(ICR_SADIE,  "SADIE",        NULL),
+        BIT(ICR_UR,     "UR",           "ur"),
+};
+
+static void decode_ICR(unsigned int val)
+{
+        decode_bits(DBGLVL "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)
+{
+        printk(DBGLVL "state:%s:%d: ISR=%08x, ICR=%08x, IBMR=%02x\n", fname, lno, ISR, ICR, IBMR);
+}
+
+#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(DBGLVL "" 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\ni2c: log: ", ICR, ISR);
+        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 !(ICR & ICR_SCLE);
+}
+
+static void i2c_pxa_abort(struct pxa_i2c *i2c)
+{
+        unsigned long timeout = jiffies + HZ/4;
+
+        if (i2c_pxa_is_slavemode(i2c)) {
+                printk(DBGLVL "i2c_pxa_transfer: called in slave mode\n");
+                return;
+        }
+
+        while (time_before(jiffies, timeout) && (IBMR & 0x1) == 0) {
+                unsigned long icr = ICR;
+
+                icr &= ~ICR_START;
+                icr |= ICR_ACKNAK | ICR_STOP | ICR_TB;
+
+                ICR = icr;
+
+                show_state(i2c);
+
+                msleep(1);
+        }
+
+        ICR &= ~(ICR_MA | ICR_START | ICR_STOP);
+}
+
+static int i2c_pxa_wait_bus_not_busy(struct pxa_i2c *i2c)
+{
+        int timeout = DEF_TIMEOUT;
+
+        while (timeout-- && ISR & (ISR_IBB | ISR_UB)) {
+                if ((ISR & 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)
+                        printk(DBGLVL "i2c_pxa_wait_master: %ld: ISR=%08x, ICR=%08x, IBMR=%02x\n",
+                               (long)jiffies, ISR, ICR, IBMR);
+
+                if (ISR & ISR_SAD) {
+                        if (i2c_debug > 0)
+                                printk(DBGLVL "i2c_pxa_wait_master: Slave detected\n");
+                        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 ((ISR & (ISR_UB | ISR_IBB)) == 0 && IBMR == 3) {
+                        if (i2c_debug > 0)
+                                printk(DBGLVL "i2c_pxa_wait_master: done\n");
+                        return 1;
+                }
+
+                msleep(1);
+        }
+
+        if (i2c_debug > 0)
+                printk(DBGLVL "i2c_pxa_wait_master: did not free\n");
+ out:
+        return 0;
+}
+
+static int i2c_pxa_set_master(struct pxa_i2c *i2c)
+{
+        if (i2c_debug)
+                printk(DBGLVL "I2C: setting to bus master\n");
+
+        if ((ISR & (ISR_UB | ISR_IBB)) != 0) {
+                printk(DBGLVL "set_master: unit is busy\n");
+                if (!i2c_pxa_wait_master(i2c)) {
+                        printk(DBGLVL "set_master: error: unit busy\n");
+                        return I2C_RETRY;
+                }
+        }
+
+        ICR |= ICR_SCLE;
+        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)
+                        printk(DBGLVL "i2c_pxa_wait_slave: %ld: ISR=%08x, ICR=%08x, IBMR=%02x\n",
+                               (long)jiffies, ISR, ICR, IBMR);
+
+                if ((ISR & (ISR_UB|ISR_IBB|ISR_SAD)) == ISR_SAD ||
+                    (ICR & ICR_SCLE) == 0) {
+                        if (i2c_debug > 1)
+                                printk(DBGLVL "i2c_pxa_wait_slave: done\n");
+                        return 1;
+                }
+
+                msleep(1);
+        }
+
+        if (i2c_debug > 0)
+                printk(DBGLVL "i2c_pxa_wait_slave: did not free\n");
+        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 (ICR & ICR_STOP) {
+                        udelay(100);
+                        ICR &= ~ICR_STOP;
+                }
+
+                if (!i2c_pxa_wait_slave(i2c)) {
+                        printk(KERN_ERR "i2c_pxa_set_slave: wait timedout\n");
+                        return;
+                }
+        }
+
+        ICR &= ~(ICR_STOP|ICR_ACKNAK|ICR_MA);
+        ICR &= ~ICR_SCLE;
+
+        if (i2c_debug) {
+                printk(DBGLVL "ICR now %08x, ISR %08x\n", ICR, ISR);
+                decode_ICR(ICR);
+        }
+}
+#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 */
+        ICR = ICR_UR;
+        ISR = I2C_ISR_INIT;
+        ICR &= ~ICR_UR;
+
+        ISAR = i2c->slave_addr;
+
+        /* set control register values */
+        ICR = I2C_ICR_INIT;
+
+#ifdef CONFIG_I2C_PXA_SLAVE
+        printk(KERN_INFO "I2C: Enabling slave mode\n");
+        ICR |= ICR_SADIE | ICR_ALDIE | ICR_SSDIE;
+#endif
+
+        i2c_pxa_set_slave(i2c, 0);
+
+        /* enable unit */
+        ICR |= ICR_IUE;
+        udelay(100);
+}
+
+
+#ifdef CONFIG_I2C_PXA_SLAVE
+/*
+ * I2C EEPROM emulation.
+ */
+static struct i2c_eeprom_emu eeprom = {
+        .size = I2C_EEPROM_EMU_SIZE,
+        .watch = LIST_HEAD_INIT(eeprom.watch),
+};
+
+struct i2c_eeprom_emu *i2c_pxa_get_eeprom(void)
+{
+        return &eeprom;
+}
+
+int i2c_eeprom_emu_addwatcher(struct i2c_eeprom_emu *emu, void *data,
+                              unsigned int addr, unsigned int size,
+                              struct i2c_eeprom_emu_watcher *watcher)
+{
+        struct i2c_eeprom_emu_watch *watch;
+        unsigned long flags;
+
+        if (addr + size > emu->size)
+                return -EINVAL;
+
+        watch = kmalloc(sizeof(struct i2c_eeprom_emu_watch), GFP_KERNEL);
+        if (watch) {
+                watch->start = addr;
+                watch->end = addr + size - 1;
+                watch->ops = watcher;
+                watch->data = data;
+
+                local_irq_save(flags);
+                list_add(&watch->node, &emu->watch);
+                local_irq_restore(flags);
+        }
+
+        return watch ? 0 : -ENOMEM;
+}
+
+void i2c_eeprom_emu_delwatcher(struct i2c_eeprom_emu *emu, void *data,
+                               struct i2c_eeprom_emu_watcher *watcher)
+{
+        struct i2c_eeprom_emu_watch *watch, *n;
+        unsigned long flags;
+
+        list_for_each_entry_safe(watch, n, &emu->watch, node) {
+                if (watch->ops == watcher && watch->data == data) {
+                        local_irq_save(flags);
+                        list_del(&watch->node);
+                        local_irq_restore(flags);
+                        kfree(watch);
+                }
+        }
+}
+
+static void i2c_eeprom_emu_event(void *ptr, i2c_slave_event_t event)
+{
+        struct i2c_eeprom_emu *emu = ptr;
+
+        eedbg(3, "i2c_eeprom_emu_event: %d\n", event);
+
+        switch (event) {
+        case I2C_SLAVE_EVENT_START_WRITE:
+                emu->seen_start = 1;
+                eedbg(2, "i2c_eeprom: write initiated\n");
+                break;
+
+        case I2C_SLAVE_EVENT_START_READ:
+                emu->seen_start = 0;
+                eedbg(2, "i2c_eeprom: read initiated\n");
+                break;
+
+        case I2C_SLAVE_EVENT_STOP:
+                emu->seen_start = 0;
+                eedbg(2, "i2c_eeprom: received stop\n");
+                break;
+
+        default:
+                eedbg(0, "i2c_eeprom: unhandled event\n");
+                break;
+        }
+}
+
+static int i2c_eeprom_emu_read(void *ptr)
+{
+        struct i2c_eeprom_emu *emu = ptr;
+        int ret;
+
+        ret = emu->bytes[emu->ptr];
+        emu->ptr = (emu->ptr + 1) % emu->size;
+
+        return ret;
+}
+
+static void i2c_eeprom_emu_write(void *ptr, unsigned int val)
+{
+        struct i2c_eeprom_emu *emu = ptr;
+        struct i2c_eeprom_emu_watch *watch;
+
+        if (emu->seen_start != 0) {
+                eedbg(2, "i2c_eeprom_emu_write: setting ptr %02x\n", val);
+                emu->ptr = val;
+                emu->seen_start = 0;
+                return;
+        }
+
+        emu->bytes[emu->ptr] = val;
+
+        eedbg(1, "i2c_eeprom_emu_write: ptr=0x%02x, val=0x%02x\n",
+              emu->ptr, val);
+
+        list_for_each_entry(watch, &emu->watch, node) {
+                if (!watch->ops || !watch->ops->write)
+                        continue;
+                if (watch->start <= emu->ptr && watch->end >= emu->ptr)
+                        watch->ops->write(watch->data, emu->ptr, val);
+        }
+
+        emu->ptr = (emu->ptr + 1) % emu->size;
+}
+
+struct i2c_slave_client eeprom_client = {
+        .data   = &eeprom,
+        .event  = i2c_eeprom_emu_event,
+        .read   = i2c_eeprom_emu_read,
+        .write  = i2c_eeprom_emu_write
+};
+
+/*
+ * 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 = i2c->slave->read(i2c->slave->data);
+
+                IDBR = ret;
+                ICR |= ICR_TB;   /* allow next byte */
+        }
+}
+
+static void i2c_pxa_slave_rxfull(struct pxa_i2c *i2c, u32 isr)
+{
+        unsigned int byte = IDBR;
+
+        if (i2c->slave != NULL)
+                i2c->slave->write(i2c->slave->data, byte);
+
+        ICR |= ICR_TB;
+}
+
+static void i2c_pxa_slave_start(struct pxa_i2c *i2c, u32 isr)
+{
+        int timeout;
+
+        if (i2c_debug > 0)
+                printk(DBGLVL "I2C: 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
+         */
+        ICR &= ~(ICR_START|ICR_STOP);
+        ICR |= ICR_TB;
+
+        timeout = 0x10000;
+
+        while (1) {
+                if ((IBMR & 2) == 2)
+                        break;
+
+                timeout--;
+
+                if (timeout <= 0) {
+                        printk(KERN_ERR "timeout waiting for SCL high\n");
+                        break;
+                }
+        }
+
+        ICR &= ~ICR_SCLE;
+}
+
+static void i2c_pxa_slave_stop(struct pxa_i2c *i2c)
+{
+        if (i2c_debug > 2)
+                printk(DBGLVL "ISR: SSD (Slave Stop)\n");
+
+        if (i2c->slave != NULL)
+                i2c->slave->event(i2c->slave->data, I2C_SLAVE_EVENT_STOP);
+
+        if (i2c_debug > 2)
+                printk(DBGLVL "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 {
+                IDBR = 0;
+                ICR |= ICR_TB;
+        }
+}
+
+static void i2c_pxa_slave_rxfull(struct pxa_i2c *i2c, u32 isr)
+{
+        ICR |= ICR_TB | ICR_ACKNAK;
+}
+
+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
+         */
+        ICR &= ~(ICR_START|ICR_STOP);
+        ICR |= ICR_TB | ICR_ACKNAK;
+
+        timeout = 0x10000;
+
+        while (1) {
+                if ((IBMR & 2) == 2)
+                        break;
+
+                timeout--;
+
+                if (timeout <= 0) {
+                        printk(KERN_ERR "timeout waiting for SCL high\n");
+                        break;
+                }
+        }
+
+        ICR &= ~ICR_SCLE;
+}
+
+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
+         */
+        IDBR = i2c_pxa_addr_byte(i2c->msg);
+
+        /*
+         * Step 2: initiate the write.
+         */
+        icr = ICR & ~(ICR_STOP | ICR_ALDIE);
+        ICR = icr | ICR_START | ICR_TB;
+}
+
+/*
+ * We are protected by the adapter bus semaphore.
+ */
+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) {
+                printk(KERN_INFO "i2c_pxa: timeout waiting for bus free\n");
+                goto out;
+        }
+
+        /*
+         * Set master mode.
+         */
+        ret = i2c_pxa_set_master(i2c);
+        if (ret) {
+                printk(KERN_INFO "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);
+
+        /*
+         * 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 = ICR & ~(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.
+                 */
+                IDBR = i2c->msg->buf[i2c->msg_ptr++];
+
+                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.
+                 */
+                IDBR = i2c_pxa_addr_byte(i2c->msg);
+
+                /*
+                 * 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;
+
+        ICR = icr;
+        show_state(i2c);
+}
+
+static void i2c_pxa_irq_rxfull(struct pxa_i2c *i2c, u32 isr)
+{
+        u32 icr = ICR & ~(ICR_START|ICR_STOP|ICR_ACKNAK|ICR_TB);
+
+        /*
+         * Read the byte.
+         */
+        i2c->msg->buf[i2c->msg_ptr++] = IDBR;
+
+        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;
+
+        ICR = icr;
+}
+
+static irqreturn_t i2c_pxa_handler(int this_irq, void *dev_id, struct pt_regs *regs)
+{
+        struct pxa_i2c *i2c = dev_id;
+        u32 isr = ISR;
+
+        if (i2c_debug > 2 && 0) {
+                printk(DBGLVL "i2c_pxa_handler: ISR=%08x, ICR=%08x, IBMR=%02x\n",
+                       isr, ICR, IBMR);
+                decode_ISR(isr);
+        }
+
+        if (i2c->irqlogidx < sizeof(i2c->isrlog)/sizeof(u32))
+                i2c->isrlog[i2c->irqlogidx++] = isr;
+
+        show_state(i2c);
+
+        /*
+         * Always clear all pending IRQs.
+         */
+        ISR = isr & (ISR_SSD|ISR_ALD|ISR_ITE|ISR_IRF|ISR_SAD|ISR_BED);
+
+        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;
+
+        for (i = adap->retries; i >= 0; i--) {
+                ret = i2c_pxa_do_xfer(i2c, msgs, num);
+                if (ret != I2C_RETRY)
+                        goto out;
+
+                if (i2c_debug)
+                        printk(KERN_INFO "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 struct i2c_algorithm i2c_pxa_algorithm = {
+        .name           = "PXA-I2C-Algorithm",
+        .id             = I2C_ALGO_PXA,
+        .master_xfer    = i2c_pxa_xfer,
+};
+
+static struct pxa_i2c i2c_pxa = {
+        .lock   = SPIN_LOCK_UNLOCKED,
+        .wait   = __WAIT_QUEUE_HEAD_INITIALIZER(i2c_pxa.wait),
+        .adap   = {
+                .name           = "pxa2xx-i2c",
+                .id             = I2C_ALGO_PXA,
+                .algo           = &i2c_pxa_algorithm,
+                .retries        = 5,
+        },
+};
+
+static int i2c_pxa_probe(struct device *dev)
+{
+        struct pxa_i2c *i2c = &i2c_pxa;
+        struct i2c_pxa_platform_data *plat = dev->platform_data;
+        int ret;
+
+#ifdef CONFIG_PXA27x
+        pxa_gpio_mode(GPIO117_I2CSCL_MD);
+        pxa_gpio_mode(GPIO118_I2CSDA_MD);
+        udelay(100);
+#endif
+
+        i2c->slave_addr = I2C_PXA_SLAVE_ADDR;
+
+#ifdef CONFIG_I2C_PXA_SLAVE
+        i2c->slave = &eeprom_client;
+        if (plat) {
+                i2c->slave_addr = plat->slave_addr;
+                if (plat->slave)
+                        i2c->slave = plat->slave;
+        }
+#endif
+
+        pxa_set_cken(CKEN14_I2C, 1);
+        ret = request_irq(IRQ_I2C, i2c_pxa_handler, SA_INTERRUPT,
+                          "pxa2xx-i2c", i2c);
+        if (ret)
+                goto out;
+
+        i2c_pxa_reset(i2c);
+
+        i2c->adap.algo_data = i2c;
+        i2c->adap.dev.parent = dev;
+
+        ret = i2c_add_adapter(&i2c->adap);
+        if (ret < 0) {
+                printk(KERN_INFO "I2C: Failed to add bus\n");
+                goto err_irq;
+        }
+
+        dev_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;
+
+ err_irq:
+        free_irq(IRQ_I2C, i2c);
+ out:
+        return ret;
+}
+
+static int i2c_pxa_remove(struct device *dev)
+{
+        struct pxa_i2c *i2c = dev_get_drvdata(dev);
+
+        dev_set_drvdata(dev, NULL);
+
+        i2c_del_adapter(&i2c->adap);
+        free_irq(IRQ_I2C, i2c);
+        pxa_set_cken(CKEN14_I2C, 0);
+
+        return 0;
+}
+
+static struct device_driver i2c_pxa_driver = {
+        .name           = "pxa2xx-i2c",
+        .bus            = &platform_bus_type,
+        .probe          = i2c_pxa_probe,
+        .remove         = i2c_pxa_remove,
+};
+
+static int __init i2c_adap_pxa_init(void)
+{
+        return driver_register(&i2c_pxa_driver);
+}
+
+static void i2c_adap_pxa_exit(void)
+{
+        return driver_unregister(&i2c_pxa_driver);
+}
+
+module_init(i2c_adap_pxa_init);
+module_exit(i2c_adap_pxa_exit);