drivers/i2c/busses/i2c-ibm_iic.c

/*
 * 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/init.h>
#include <linux/interrupt.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <linux/i2c.h>
#include <linux/i2c-id.h>

#ifdef CONFIG_IBM_OCP
#include <asm/ocp.h>
#include <asm/ibm4xx.h>
#else
#include <linux/of_platform.h>
#endif

#include "i2c-ibm_iic.h"

#define DRIVER_VERSION "2.2"

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

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

static int 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"
	       KERN_DEBUG "  sts      = 0x%02x, extsts = 0x%02x\n"
	       KERN_DEBUG "  clkdiv   = 0x%02x, xfrcnt = 0x%02x\n"
	       KERN_DEBUG "  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 i2c_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 i2c_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 = (u8)((p->addr << 1) | ((p->flags & I2C_M_RD) ? 1 : 0));
	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 * HZ);

		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 * HZ;

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

			if (unlikely(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, transfered %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);

	if (!num)
		return 0;

	/* 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 happend.
		 * 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);
}

#ifdef CONFIG_IBM_OCP
/*
 * Register single IIC interface
 */
static int __devinit iic_probe(struct ocp_device *ocp){

	struct ibm_iic_private* dev;
	struct i2c_adapter* adap;
	struct ocp_func_iic_data* iic_data = ocp->def->additions;
	int ret;

	if (!iic_data)
		printk(KERN_WARNING"ibm-iic%d: missing additional data!\n",
			ocp->def->index);

	if (!(dev = kzalloc(sizeof(*dev), GFP_KERNEL))) {
		printk(KERN_ERR "ibm-iic%d: failed to allocate device data\n",
			ocp->def->index);
		return -ENOMEM;
	}

	dev->idx = ocp->def->index;
	ocp_set_drvdata(ocp, dev);

	if (!request_mem_region(ocp->def->paddr, sizeof(struct iic_regs),
				"ibm_iic")) {
		ret = -EBUSY;
		goto fail1;
	}

	if (!(dev->vaddr = ioremap(ocp->def->paddr, sizeof(struct iic_regs)))){
		printk(KERN_ERR "ibm-iic%d: failed to ioremap device registers\n",
			dev->idx);
		ret = -ENXIO;
		goto fail2;
	}

	init_waitqueue_head(&dev->wq);

	dev->irq = iic_force_poll ? -1 : ocp->def->irq;
	if (dev->irq >= 0){
		/* Disable interrupts until we finish initialization,
		   assumes level-sensitive IRQ setup...
		 */
		iic_interrupt_mode(dev, 0);
		if (request_irq(dev->irq, iic_handler, 0, "IBM IIC", dev)){
			printk(KERN_ERR "ibm-iic%d: request_irq %d failed\n",
				dev->idx, dev->irq);
			/* Fallback to the polling mode */
			dev->irq = -1;
		}
	}

	if (dev->irq < 0)
		printk(KERN_WARNING "ibm-iic%d: using polling mode\n",
			dev->idx);

	/* Board specific settings */
	dev->fast_mode = iic_force_fast ? 1 : (iic_data ? iic_data->fast_mode : 0);

	/* clckdiv is the same for *all* IIC interfaces,
	 * but I'd rather make a copy than introduce another global. --ebs
	 */
	dev->clckdiv = iic_clckdiv(ocp_sys_info.opb_bus_freq);
	DBG("%d: clckdiv = %d\n", dev->idx, dev->clckdiv);

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

	/* Register it with i2c layer */
	adap = &dev->adap;
	adap->dev.parent = &ocp->dev;
	strcpy(adap->name, "IBM IIC");
	i2c_set_adapdata(adap, dev);
	adap->id = I2C_HW_OCP;
	adap->class = I2C_CLASS_HWMON;
	adap->algo = &iic_algo;
	adap->client_register = NULL;
	adap->client_unregister = NULL;
	adap->timeout = 1;

	/*
	 * If "dev->idx" 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.
	 */
	adap->nr = dev->idx >= 0 ? dev->idx : 0;

	if ((ret = i2c_add_numbered_adapter(adap)) < 0) {
		printk(KERN_ERR "ibm-iic%d: failed to register i2c adapter\n",
			dev->idx);
		goto fail;
	}

	printk(KERN_INFO "ibm-iic%d: using %s mode\n", dev->idx,
		dev->fast_mode ? "fast (400 kHz)" : "standard (100 kHz)");

	return 0;

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

	iounmap(dev->vaddr);
fail2:
	release_mem_region(ocp->def->paddr, sizeof(struct iic_regs));
fail1:
	ocp_set_drvdata(ocp, NULL);
	kfree(dev);
	return ret;
}

/*
 * Cleanup initialized IIC interface
 */
static void __devexit iic_remove(struct ocp_device *ocp)
{
	struct ibm_iic_private* dev = (struct ibm_iic_private*)ocp_get_drvdata(ocp);
	BUG_ON(dev == NULL);
	if (i2c_del_adapter(&dev->adap)){
		printk(KERN_ERR "ibm-iic%d: failed to delete i2c adapter :(\n",
			dev->idx);
		/* That's *very* bad, just shutdown IRQ ... */
		if (dev->irq >= 0){
		    iic_interrupt_mode(dev, 0);
		    free_irq(dev->irq, dev);
		    dev->irq = -1;
		}
	} else {
		if (dev->irq >= 0){
		    iic_interrupt_mode(dev, 0);
		    free_irq(dev->irq, dev);
		}
		iounmap(dev->vaddr);
		release_mem_region(ocp->def->paddr, sizeof(struct iic_regs));
		kfree(dev);
	}
}

static struct ocp_device_id ibm_iic_ids[] __devinitdata =
{
	{ .vendor = OCP_VENDOR_IBM, .function = OCP_FUNC_IIC },
	{ .vendor = OCP_VENDOR_INVALID }
};

MODULE_DEVICE_TABLE(ocp, ibm_iic_ids);

static struct ocp_driver ibm_iic_driver =
{
	.name 		= "iic",
	.id_table	= ibm_iic_ids,
	.probe		= iic_probe,
	.remove		= __devexit_p(iic_remove),
#if defined(CONFIG_PM)
	.suspend	= NULL,
	.resume		= NULL,
#endif
};

static int __init iic_init(void)
{
	printk(KERN_INFO "IBM IIC driver v" DRIVER_VERSION "\n");
	return ocp_register_driver(&ibm_iic_driver);
}

static void __exit iic_exit(void)
{
	ocp_unregister_driver(&ibm_iic_driver);
}

#else  /* !CONFIG_IBM_OCP */

static int __devinit iic_request_irq(struct of_device *ofdev,
				     struct ibm_iic_private *dev)
{
	struct device_node *np = ofdev->node;
	int irq;

	if (iic_force_poll)
		return NO_IRQ;

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

	/* 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 NO_IRQ;
	}

	return irq;
}

/*
 * Register single IIC interface
 */
static int __devinit iic_probe(struct of_device *ofdev,
			       const struct of_device_id *match)
{
	struct device_node *np = ofdev->node;
	struct ibm_iic_private *dev;
	struct i2c_adapter *adap;
	const u32 *indexp, *freq;
	int ret;

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

	dev_set_drvdata(&ofdev->dev, dev);

	indexp = of_get_property(np, "index", NULL);
	if (!indexp) {
		dev_err(&ofdev->dev, "no index specified\n");
		ret = -EINVAL;
		goto error_cleanup;
	}
	dev->idx = *indexp;

	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 == NO_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;
	strlcpy(adap->name, "IBM IIC", sizeof(adap->name));
	i2c_set_adapdata(adap, dev);
	adap->id = I2C_HW_OCP;
	adap->class = I2C_CLASS_HWMON;
	adap->algo = &iic_algo;
	adap->timeout = 1;
	adap->nr = dev->idx;

	ret = i2c_add_numbered_adapter(adap);
	if (ret  < 0) {
		dev_err(&ofdev->dev, "failed to register i2c adapter\n");
		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 != NO_IRQ) {
		iic_interrupt_mode(dev, 0);
		free_irq(dev->irq, dev);
	}

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

	dev_set_drvdata(&ofdev->dev, NULL);
	kfree(dev);
	return ret;
}

/*
 * Cleanup initialized IIC interface
 */
static int __devexit iic_remove(struct of_device *ofdev)
{
	struct ibm_iic_private *dev = dev_get_drvdata(&ofdev->dev);

	dev_set_drvdata(&ofdev->dev, NULL);

	i2c_del_adapter(&dev->adap);

	if (dev->irq != NO_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-405ex", },
	{ .compatible = "ibm,iic-405gp", },
	{ .compatible = "ibm,iic-440gp", },
	{ .compatible = "ibm,iic-440gpx", },
	{ .compatible = "ibm,iic-440grx", },
	{}
};

static struct of_platform_driver ibm_iic_driver = {
	.name	= "ibm-iic",
	.match_table = ibm_iic_match,
	.probe	= iic_probe,
	.remove	= __devexit_p(iic_remove),
};

static int __init iic_init(void)
{
	return of_register_platform_driver(&ibm_iic_driver);
}

static void __exit iic_exit(void)
{
	of_unregister_platform_driver(&ibm_iic_driver);
}
#endif /* CONFIG_IBM_OCP */

module_init(iic_init);
module_exit(iic_exit);