/*
 * drivers/i2c/busses/i2c-ibm_iic.c
 *
 * Support for the IIC peripheral on IBM PPC 4xx
 *
 * Copyright (c) 2003, 2004 Zultys Technologies.
 * Eugene Surovegin <eugene.surovegin@zultys.com> or <ebs@ebshome.net>
 *
 * Copyright (c) 2008 PIKA Technologies
 * Sean MacLennan <smaclennan@pikatech.com>
 *
 * Based on original work by
 *      Ian DaSilva  <idasilva@mvista.com>
 *      Armin Kuster <akuster@mvista.com>
 *      Matt Porter  <mporter@mvista.com>
 *
 *      Copyright 2000-2003 MontaVista Software Inc.
 *
 * Original driver version was highly leveraged from i2c-elektor.c
 *
 *      Copyright 1995-97 Simon G. Vogl
 *                1998-99 Hans Berglund
 *
 *      With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi>
 *      and even Frodo Looijaard <frodol@dds.nl>
 *
 * 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.
 *
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/ioport.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/sched/signal.h>

#include <asm/irq.h>
#include <linux/io.h>
#include <linux/i2c.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/of_platform.h>

#include "i2c-ibm_iic.h"

#define DRIVER_VERSION "2.2"

MODULE_DESCRIPTION("IBM IIC driver v" DRIVER_VERSION);
MODULE_LICENSE("GPL");

static bool iic_force_poll;
module_param(iic_force_poll, bool, 0);
MODULE_PARM_DESC(iic_force_poll, "Force polling mode");

static bool iic_force_fast;
module_param(iic_force_fast, bool, 0);
MODULE_PARM_DESC(iic_force_fast, "Force fast mode (400 kHz)");

#define DBG_LEVEL 0

#ifdef DBG
#undef DBG
#endif

#ifdef DBG2
#undef DBG2
#endif

#if DBG_LEVEL > 0
#  define DBG(f,x...)   printk(KERN_DEBUG "ibm-iic" f, ##x)
#else
#  define DBG(f,x...)   ((void)0)
#endif
#if DBG_LEVEL > 1
#  define DBG2(f,x...)  DBG(f, ##x)
#else
#  define DBG2(f,x...)  ((void)0)
#endif
#if DBG_LEVEL > 2
static void dump_iic_regs(const char* header, struct ibm_iic_private* dev)
{
        volatile struct iic_regs __iomem *iic = dev->vaddr;
        printk(KERN_DEBUG "ibm-iic%d: %s\n", dev->idx, header);
        printk(KERN_DEBUG
               "  cntl     = 0x%02x, mdcntl = 0x%02x\n"
               "  sts      = 0x%02x, extsts = 0x%02x\n"
               "  clkdiv   = 0x%02x, xfrcnt = 0x%02x\n"
               "  xtcntlss = 0x%02x, directcntl = 0x%02x\n",
                in_8(&iic->cntl), in_8(&iic->mdcntl), in_8(&iic->sts),
                in_8(&iic->extsts), in_8(&iic->clkdiv), in_8(&iic->xfrcnt),
                in_8(&iic->xtcntlss), in_8(&iic->directcntl));
}
#  define DUMP_REGS(h,dev)      dump_iic_regs((h),(dev))
#else
#  define DUMP_REGS(h,dev)      ((void)0)
#endif

/* Bus timings (in ns) for bit-banging */
static struct ibm_iic_timings {
        unsigned int hd_sta;
        unsigned int su_sto;
        unsigned int low;
        unsigned int high;
        unsigned int buf;
} timings [] = {
/* Standard mode (100 KHz) */
{
        .hd_sta = 4000,
        .su_sto = 4000,
        .low    = 4700,
        .high   = 4000,
        .buf    = 4700,
},
/* Fast mode (400 KHz) */
{
        .hd_sta = 600,
        .su_sto = 600,
        .low    = 1300,
        .high   = 600,
        .buf    = 1300,
}};

/* Enable/disable interrupt generation */
static inline void iic_interrupt_mode(struct ibm_iic_private* dev, int enable)
{
        out_8(&dev->vaddr->intmsk, enable ? INTRMSK_EIMTC : 0);
}

/*
 * Initialize IIC interface.
 */
static void iic_dev_init(struct ibm_iic_private* dev)
{
        volatile struct iic_regs __iomem *iic = dev->vaddr;

        DBG("%d: init\n", dev->idx);

        /* Clear master address */
        out_8(&iic->lmadr, 0);
        out_8(&iic->hmadr, 0);

        /* Clear slave address */
        out_8(&iic->lsadr, 0);
        out_8(&iic->hsadr, 0);

        /* Clear status & extended status */
        out_8(&iic->sts, STS_SCMP | STS_IRQA);
        out_8(&iic->extsts, EXTSTS_IRQP | EXTSTS_IRQD | EXTSTS_LA
                            | EXTSTS_ICT | EXTSTS_XFRA);

        /* Set clock divider */
        out_8(&iic->clkdiv, dev->clckdiv);

        /* Clear transfer count */
        out_8(&iic->xfrcnt, 0);

        /* Clear extended control and status */
        out_8(&iic->xtcntlss, XTCNTLSS_SRC | XTCNTLSS_SRS | XTCNTLSS_SWC
                            | XTCNTLSS_SWS);

        /* Clear control register */
        out_8(&iic->cntl, 0);

        /* Enable interrupts if possible */
        iic_interrupt_mode(dev, dev->irq >= 0);

        /* Set mode control */
        out_8(&iic->mdcntl, MDCNTL_FMDB | MDCNTL_EINT | MDCNTL_EUBS
                            | (dev->fast_mode ? MDCNTL_FSM : 0));

        DUMP_REGS("iic_init", dev);
}

/*
 * Reset IIC interface
 */
static void iic_dev_reset(struct ibm_iic_private* dev)
{
        volatile struct iic_regs __iomem *iic = dev->vaddr;
        int i;
        u8 dc;

        DBG("%d: soft reset\n", dev->idx);
        DUMP_REGS("reset", dev);

        /* Place chip in the reset state */
        out_8(&iic->xtcntlss, XTCNTLSS_SRST);

        /* Check if bus is free */
        dc = in_8(&iic->directcntl);
        if (!DIRCTNL_FREE(dc)){
                DBG("%d: trying to regain bus control\n", dev->idx);

                /* Try to set bus free state */
                out_8(&iic->directcntl, DIRCNTL_SDAC | DIRCNTL_SCC);

                /* Wait until we regain bus control */
                for (i = 0; i < 100; ++i){
                        dc = in_8(&iic->directcntl);
                        if (DIRCTNL_FREE(dc))
                                break;

                        /* Toggle SCL line */
                        dc ^= DIRCNTL_SCC;
                        out_8(&iic->directcntl, dc);
                        udelay(10);
                        dc ^= DIRCNTL_SCC;
                        out_8(&iic->directcntl, dc);

                        /* be nice */
                        cond_resched();
                }
        }

        /* Remove reset */
        out_8(&iic->xtcntlss, 0);

        /* Reinitialize interface */
        iic_dev_init(dev);
}

/*
 * Do 0-length transaction using bit-banging through IIC_DIRECTCNTL register.
 */

/* Wait for SCL and/or SDA to be high */
static int iic_dc_wait(volatile struct iic_regs __iomem *iic, u8 mask)
{
        unsigned long x = jiffies + HZ / 28 + 2;
        while ((in_8(&iic->directcntl) & mask) != mask){
                if (unlikely(time_after(jiffies, x)))
                        return -1;
                cond_resched();
        }
        return 0;
}

static int iic_smbus_quick(struct ibm_iic_private* dev, const struct i2c_msg* p)
{
        volatile struct iic_regs __iomem *iic = dev->vaddr;
        const struct ibm_iic_timings *t = &timings[dev->fast_mode ? 1 : 0];
        u8 mask, v, sda;
        int i, res;

        /* Only 7-bit addresses are supported */
        if (unlikely(p->flags & I2C_M_TEN)){
                DBG("%d: smbus_quick - 10 bit addresses are not supported\n",
                        dev->idx);
                return -EINVAL;
        }

        DBG("%d: smbus_quick(0x%02x)\n", dev->idx, p->addr);

        /* Reset IIC interface */
        out_8(&iic->xtcntlss, XTCNTLSS_SRST);

        /* Wait for bus to become free */
        out_8(&iic->directcntl, DIRCNTL_SDAC | DIRCNTL_SCC);
        if (unlikely(iic_dc_wait(iic, DIRCNTL_MSDA | DIRCNTL_MSC)))
                goto err;
        ndelay(t->buf);

        /* START */
        out_8(&iic->directcntl, DIRCNTL_SCC);
        sda = 0;
        ndelay(t->hd_sta);

        /* Send address */
        v = i2c_8bit_addr_from_msg(p);
        for (i = 0, mask = 0x80; i < 8; ++i, mask >>= 1){
                out_8(&iic->directcntl, sda);
                ndelay(t->low / 2);
                sda = (v & mask) ? DIRCNTL_SDAC : 0;
                out_8(&iic->directcntl, sda);
                ndelay(t->low / 2);

                out_8(&iic->directcntl, DIRCNTL_SCC | sda);
                if (unlikely(iic_dc_wait(iic, DIRCNTL_MSC)))
                        goto err;
                ndelay(t->high);
        }

        /* ACK */
        out_8(&iic->directcntl, sda);
        ndelay(t->low / 2);
        out_8(&iic->directcntl, DIRCNTL_SDAC);
        ndelay(t->low / 2);
        out_8(&iic->directcntl, DIRCNTL_SDAC | DIRCNTL_SCC);
        if (unlikely(iic_dc_wait(iic, DIRCNTL_MSC)))
                goto err;
        res = (in_8(&iic->directcntl) & DIRCNTL_MSDA) ? -EREMOTEIO : 1;
        ndelay(t->high);

        /* STOP */
        out_8(&iic->directcntl, 0);
        ndelay(t->low);
        out_8(&iic->directcntl, DIRCNTL_SCC);
        if (unlikely(iic_dc_wait(iic, DIRCNTL_MSC)))
                goto err;
        ndelay(t->su_sto);
        out_8(&iic->directcntl, DIRCNTL_SDAC | DIRCNTL_SCC);

        ndelay(t->buf);

        DBG("%d: smbus_quick -> %s\n", dev->idx, res ? "NACK" : "ACK");
out:
        /* Remove reset */
        out_8(&iic->xtcntlss, 0);

        /* Reinitialize interface */
        iic_dev_init(dev);

        return res;
err:
        DBG("%d: smbus_quick - bus is stuck\n", dev->idx);
        res = -EREMOTEIO;
        goto out;
}

/*
 * IIC interrupt handler
 */
static irqreturn_t iic_handler(int irq, void *dev_id)
{
        struct ibm_iic_private* dev = (struct ibm_iic_private*)dev_id;
        volatile struct iic_regs __iomem *iic = dev->vaddr;

        DBG2("%d: irq handler, STS = 0x%02x, EXTSTS = 0x%02x\n",
             dev->idx, in_8(&iic->sts), in_8(&iic->extsts));

        /* Acknowledge IRQ and wakeup iic_wait_for_tc */
        out_8(&iic->sts, STS_IRQA | STS_SCMP);
        wake_up_interruptible(&dev->wq);

        return IRQ_HANDLED;
}

/*
 * Get master transfer result and clear errors if any.
 * Returns the number of actually transferred bytes or error (<0)
 */
static int iic_xfer_result(struct ibm_iic_private* dev)
{
        volatile struct iic_regs __iomem *iic = dev->vaddr;

        if (unlikely(in_8(&iic->sts) & STS_ERR)){
                DBG("%d: xfer error, EXTSTS = 0x%02x\n", dev->idx,
                        in_8(&iic->extsts));

                /* Clear errors and possible pending IRQs */
                out_8(&iic->extsts, EXTSTS_IRQP | EXTSTS_IRQD |
                        EXTSTS_LA | EXTSTS_ICT | EXTSTS_XFRA);

                /* Flush master data buffer */
                out_8(&iic->mdcntl, in_8(&iic->mdcntl) | MDCNTL_FMDB);

                /* Is bus free?
                 * If error happened during combined xfer
                 * IIC interface is usually stuck in some strange
                 * state, the only way out - soft reset.
                 */
                if ((in_8(&iic->extsts) & EXTSTS_BCS_MASK) != EXTSTS_BCS_FREE){
                        DBG("%d: bus is stuck, resetting\n", dev->idx);
                        iic_dev_reset(dev);
                }
                return -EREMOTEIO;
        }
        else
                return in_8(&iic->xfrcnt) & XFRCNT_MTC_MASK;
}

/*
 * Try to abort active transfer.
 */
static void iic_abort_xfer(struct ibm_iic_private* dev)
{
        volatile struct iic_regs __iomem *iic = dev->vaddr;
        unsigned long x;

        DBG("%d: iic_abort_xfer\n", dev->idx);

        out_8(&iic->cntl, CNTL_HMT);

        /*
         * Wait for the abort command to complete.
         * It's not worth to be optimized, just poll (timeout >= 1 tick)
         */
        x = jiffies + 2;
        while ((in_8(&iic->extsts) & EXTSTS_BCS_MASK) != EXTSTS_BCS_FREE){
                if (time_after(jiffies, x)){
                        DBG("%d: abort timeout, resetting...\n", dev->idx);
                        iic_dev_reset(dev);
                        return;
                }
                schedule();
        }

        /* Just to clear errors */
        iic_xfer_result(dev);
}

/*
 * Wait for master transfer to complete.
 * It puts current process to sleep until we get interrupt or timeout expires.
 * Returns the number of transferred bytes or error (<0)
 */
static int iic_wait_for_tc(struct ibm_iic_private* dev){

        volatile struct iic_regs __iomem *iic = dev->vaddr;
        int ret = 0;

        if (dev->irq >= 0){
                /* Interrupt mode */
                ret = wait_event_interruptible_timeout(dev->wq,
                        !(in_8(&iic->sts) & STS_PT), dev->adap.timeout);

                if (unlikely(ret < 0))
                        DBG("%d: wait interrupted\n", dev->idx);
                else if (unlikely(in_8(&iic->sts) & STS_PT)){
                        DBG("%d: wait timeout\n", dev->idx);
                        ret = -ETIMEDOUT;
                }
        }
        else {
                /* Polling mode */
                unsigned long x = jiffies + dev->adap.timeout;

                while (in_8(&iic->sts) & STS_PT){
                        if (unlikely(time_after(jiffies, x))){
                                DBG("%d: poll timeout\n", dev->idx);
                                ret = -ETIMEDOUT;
                                break;
                        }

                        if (signal_pending(current)){
                                DBG("%d: poll interrupted\n", dev->idx);
                                ret = -ERESTARTSYS;
                                break;
                        }
                        schedule();
                }
        }

        if (unlikely(ret < 0))
                iic_abort_xfer(dev);
        else
                ret = iic_xfer_result(dev);

        DBG2("%d: iic_wait_for_tc -> %d\n", dev->idx, ret);

        return ret;
}

/*
 * Low level master transfer routine
 */
static int iic_xfer_bytes(struct ibm_iic_private* dev, struct i2c_msg* pm,
                          int combined_xfer)
{
        volatile struct iic_regs __iomem *iic = dev->vaddr;
        char* buf = pm->buf;
        int i, j, loops, ret = 0;
        int len = pm->len;

        u8 cntl = (in_8(&iic->cntl) & CNTL_AMD) | CNTL_PT;
        if (pm->flags & I2C_M_RD)
                cntl |= CNTL_RW;

        loops = (len + 3) / 4;
        for (i = 0; i < loops; ++i, len -= 4){
                int count = len > 4 ? 4 : len;
                u8 cmd = cntl | ((count - 1) << CNTL_TCT_SHIFT);

                if (!(cntl & CNTL_RW))
                        for (j = 0; j < count; ++j)
                                out_8((void __iomem *)&iic->mdbuf, *buf++);

                if (i < loops - 1)
                        cmd |= CNTL_CHT;
                else if (combined_xfer)
                        cmd |= CNTL_RPST;

                DBG2("%d: xfer_bytes, %d, CNTL = 0x%02x\n", dev->idx, count, cmd);

                /* Start transfer */
                out_8(&iic->cntl, cmd);

                /* Wait for completion */
                ret = iic_wait_for_tc(dev);

                if (unlikely(ret < 0))
                        break;
                else if (unlikely(ret != count)){
                        DBG("%d: xfer_bytes, requested %d, transferred %d\n",
                                dev->idx, count, ret);

                        /* If it's not a last part of xfer, abort it */
                        if (combined_xfer || (i < loops - 1))
                                iic_abort_xfer(dev);

                        ret = -EREMOTEIO;
                        break;
                }

                if (cntl & CNTL_RW)
                        for (j = 0; j < count; ++j)
                                *buf++ = in_8((void __iomem *)&iic->mdbuf);
        }

        return ret > 0 ? 0 : ret;
}

/*
 * Set target slave address for master transfer
 */
static inline void iic_address(struct ibm_iic_private* dev, struct i2c_msg* msg)
{
        volatile struct iic_regs __iomem *iic = dev->vaddr;
        u16 addr = msg->addr;

        DBG2("%d: iic_address, 0x%03x (%d-bit)\n", dev->idx,
                addr, msg->flags & I2C_M_TEN ? 10 : 7);

        if (msg->flags & I2C_M_TEN){
            out_8(&iic->cntl, CNTL_AMD);
            out_8(&iic->lmadr, addr);
            out_8(&iic->hmadr, 0xf0 | ((addr >> 7) & 0x06));
        }
        else {
            out_8(&iic->cntl, 0);
            out_8(&iic->lmadr, addr << 1);
        }
}

static inline int iic_invalid_address(const struct i2c_msg* p)
{
        return (p->addr > 0x3ff) || (!(p->flags & I2C_M_TEN) && (p->addr > 0x7f));
}

static inline int iic_address_neq(const struct i2c_msg* p1,
                                  const struct i2c_msg* p2)
{
        return (p1->addr != p2->addr)
                || ((p1->flags & I2C_M_TEN) != (p2->flags & I2C_M_TEN));
}

/*
 * Generic master transfer entrypoint.
 * Returns the number of processed messages or error (<0)
 */
static int iic_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
{
        struct ibm_iic_private* dev = (struct ibm_iic_private*)(i2c_get_adapdata(adap));
        volatile struct iic_regs __iomem *iic = dev->vaddr;
        int i, ret = 0;

        DBG2("%d: iic_xfer, %d msg(s)\n", dev->idx, num);

        /* Check the sanity of the passed messages.
         * Uhh, generic i2c layer is more suitable place for such code...
         */
        if (unlikely(iic_invalid_address(&msgs[0]))){
                DBG("%d: invalid address 0x%03x (%d-bit)\n", dev->idx,
                        msgs[0].addr, msgs[0].flags & I2C_M_TEN ? 10 : 7);
                return -EINVAL;
        }
        for (i = 0; i < num; ++i){
                if (unlikely(msgs[i].len <= 0)){
                        if (num == 1 && !msgs[0].len){
                                /* Special case for I2C_SMBUS_QUICK emulation.
                                 * IBM IIC doesn't support 0-length transactions
                                 * so we have to emulate them using bit-banging.
                                 */
                                return iic_smbus_quick(dev, &msgs[0]);
                        }
                        DBG("%d: invalid len %d in msg[%d]\n", dev->idx,
                                msgs[i].len, i);
                        return -EINVAL;
                }
                if (unlikely(iic_address_neq(&msgs[0], &msgs[i]))){
                        DBG("%d: invalid addr in msg[%d]\n", dev->idx, i);
                        return -EINVAL;
                }
        }

        /* Check bus state */
        if (unlikely((in_8(&iic->extsts) & EXTSTS_BCS_MASK) != EXTSTS_BCS_FREE)){
                DBG("%d: iic_xfer, bus is not free\n", dev->idx);

                /* Usually it means something serious has happened.
                 * We *cannot* have unfinished previous transfer
                 * so it doesn't make any sense to try to stop it.
                 * Probably we were not able to recover from the
                 * previous error.
                 * The only *reasonable* thing I can think of here
                 * is soft reset.  --ebs
                 */
                iic_dev_reset(dev);

                if ((in_8(&iic->extsts) & EXTSTS_BCS_MASK) != EXTSTS_BCS_FREE){
                        DBG("%d: iic_xfer, bus is still not free\n", dev->idx);
                        return -EREMOTEIO;
                }
        }
        else {
                /* Flush master data buffer (just in case) */
                out_8(&iic->mdcntl, in_8(&iic->mdcntl) | MDCNTL_FMDB);
        }

        /* Load slave address */
        iic_address(dev, &msgs[0]);

        /* Do real transfer */
        for (i = 0; i < num && !ret; ++i)
                ret = iic_xfer_bytes(dev, &msgs[i], i < num - 1);

        return ret < 0 ? ret : num;
}

static u32 iic_func(struct i2c_adapter *adap)
{
        return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_10BIT_ADDR;
}

static const struct i2c_algorithm iic_algo = {
        .master_xfer    = iic_xfer,
        .functionality  = iic_func
};

/*
 * Calculates IICx_CLCKDIV value for a specific OPB clock frequency
 */
static inline u8 iic_clckdiv(unsigned int opb)
{
        /* Compatibility kludge, should go away after all cards
         * are fixed to fill correct value for opbfreq.
         * Previous driver version used hardcoded divider value 4,
         * it corresponds to OPB frequency from the range (40, 50] MHz
         */
        if (!opb){
                printk(KERN_WARNING "ibm-iic: using compatibility value for OPB freq,"
                        " fix your board specific setup\n");
                opb = 50000000;
        }

        /* Convert to MHz */
        opb /= 1000000;

        if (opb < 20 || opb > 150){
                printk(KERN_WARNING "ibm-iic: invalid OPB clock frequency %u MHz\n",
                        opb);
                opb = opb < 20 ? 20 : 150;
        }
        return (u8)((opb + 9) / 10 - 1);
}

static int iic_request_irq(struct platform_device *ofdev,
                                     struct ibm_iic_private *dev)
{
        struct device_node *np = ofdev->dev.of_node;
        int irq;

        if (iic_force_poll)
                return 0;

        irq = irq_of_parse_and_map(np, 0);
        if (!irq) {
                dev_err(&ofdev->dev, "irq_of_parse_and_map failed\n");
                return 0;
        }

        /* Disable interrupts until we finish initialization, assumes
         *  level-sensitive IRQ setup...
         */
        iic_interrupt_mode(dev, 0);
        if (request_irq(irq, iic_handler, 0, "IBM IIC", dev)) {
                dev_err(&ofdev->dev, "request_irq %d failed\n", irq);
                /* Fallback to the polling mode */
                return 0;
        }

        return irq;
}

/*
 * Register single IIC interface
 */
static int iic_probe(struct platform_device *ofdev)
{
        struct device_node *np = ofdev->dev.of_node;
        struct ibm_iic_private *dev;
        struct i2c_adapter *adap;
        const u32 *freq;
        int ret;

        dev = kzalloc(sizeof(*dev), GFP_KERNEL);
        if (!dev) {
                dev_err(&ofdev->dev, "failed to allocate device data\n");
                return -ENOMEM;
        }

        platform_set_drvdata(ofdev, dev);

        dev->vaddr = of_iomap(np, 0);
        if (dev->vaddr == NULL) {
                dev_err(&ofdev->dev, "failed to iomap device\n");
                ret = -ENXIO;
                goto error_cleanup;
        }

        init_waitqueue_head(&dev->wq);

        dev->irq = iic_request_irq(ofdev, dev);
        if (!dev->irq)
                dev_warn(&ofdev->dev, "using polling mode\n");

        /* Board specific settings */
        if (iic_force_fast || of_get_property(np, "fast-mode", NULL))
                dev->fast_mode = 1;

        freq = of_get_property(np, "clock-frequency", NULL);
        if (freq == NULL) {
                freq = of_get_property(np->parent, "clock-frequency", NULL);
                if (freq == NULL) {
                        dev_err(&ofdev->dev, "Unable to get bus frequency\n");
                        ret = -EINVAL;
                        goto error_cleanup;
                }
        }

        dev->clckdiv = iic_clckdiv(*freq);
        dev_dbg(&ofdev->dev, "clckdiv = %d\n", dev->clckdiv);

        /* Initialize IIC interface */
        iic_dev_init(dev);

        /* Register it with i2c layer */
        adap = &dev->adap;
        adap->dev.parent = &ofdev->dev;
        adap->dev.of_node = of_node_get(np);
        strlcpy(adap->name, "IBM IIC", sizeof(adap->name));
        i2c_set_adapdata(adap, dev);
        adap->class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
        adap->algo = &iic_algo;
        adap->timeout = HZ;

        ret = i2c_add_adapter(adap);
        if (ret  < 0)
                goto error_cleanup;

        dev_info(&ofdev->dev, "using %s mode\n",
                 dev->fast_mode ? "fast (400 kHz)" : "standard (100 kHz)");

        return 0;

error_cleanup:
        if (dev->irq) {
                iic_interrupt_mode(dev, 0);
                free_irq(dev->irq, dev);
        }

        if (dev->vaddr)
                iounmap(dev->vaddr);

        kfree(dev);
        return ret;
}

/*
 * Cleanup initialized IIC interface
 */
static int iic_remove(struct platform_device *ofdev)
{
        struct ibm_iic_private *dev = platform_get_drvdata(ofdev);

        i2c_del_adapter(&dev->adap);

        if (dev->irq) {
                iic_interrupt_mode(dev, 0);
                free_irq(dev->irq, dev);
        }

        iounmap(dev->vaddr);
        kfree(dev);

        return 0;
}

static const struct of_device_id ibm_iic_match[] = {
        { .compatible = "ibm,iic", },
        {}
};
MODULE_DEVICE_TABLE(of, ibm_iic_match);

static struct platform_driver ibm_iic_driver = {
        .driver = {
                .name = "ibm-iic",
                .of_match_table = ibm_iic_match,
        },
        .probe  = iic_probe,
        .remove = iic_remove,
};

module_platform_driver(ibm_iic_driver);