drivers/i2c/busses/i2c-s3c2410.c - android_kernel_htc_msm8960 - Gitiles

 /* linux/drivers/i2c/busses/i2c-s3c2410.c
  *
  * Copyright (C) 2004,2005 Simtec Electronics
  *	Ben Dooks <ben@simtec.co.uk>
  *
  * S3C2410 I2C Controller
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
  * (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

 #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/interrupt.h>
 #include <linux/delay.h>
 #include <linux/errno.h>
 #include <linux/err.h>
 #include <linux/platform_device.h>
 #include <linux/clk.h>

 #include <asm/hardware.h>
 #include <asm/irq.h>
 #include <asm/io.h>

 #include <asm/arch/regs-gpio.h>
 #include <asm/arch/regs-iic.h>
 #include <asm/arch/iic.h>

 /* i2c controller state */

 enum s3c24xx_i2c_state {
 	STATE_IDLE,
 	STATE_START,
 	STATE_READ,
 	STATE_WRITE,
 	STATE_STOP
 };

 struct s3c24xx_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;

 	enum s3c24xx_i2c_state	state;

 	void __iomem		*regs;
 	struct clk		*clk;
 	struct device		*dev;
 	struct resource		*irq;
 	struct resource		*ioarea;
 	struct i2c_adapter	adap;
 };

 /* default platform data to use if not supplied in the platform_device
 */

 static struct s3c2410_platform_i2c s3c24xx_i2c_default_platform = {
 	.flags		= 0,
 	.slave_addr	= 0x10,
 	.bus_freq	= 100*1000,
 	.max_freq	= 400*1000,
 	.sda_delay	= S3C2410_IICLC_SDA_DELAY5 | S3C2410_IICLC_FILTER_ON,
 };

 /* s3c24xx_i2c_is2440()
  *
  * return true is this is an s3c2440
 */

 static inline int s3c24xx_i2c_is2440(struct s3c24xx_i2c *i2c)
 {
 	struct platform_device *pdev = to_platform_device(i2c->dev);

 	return !strcmp(pdev->name, "s3c2440-i2c");
 }


 /* s3c24xx_i2c_get_platformdata
  *
  * get the platform data associated with the given device, or return
  * the default if there is none
 */

 static inline struct s3c2410_platform_i2c *s3c24xx_i2c_get_platformdata(struct device *dev)
 {
 	if (dev->platform_data != NULL)
 		return (struct s3c2410_platform_i2c *)dev->platform_data;

 	return &s3c24xx_i2c_default_platform;
 }

 /* s3c24xx_i2c_master_complete
  *
  * complete the message and wake up the caller, using the given return code,
  * or zero to mean ok.
 */

 static inline void s3c24xx_i2c_master_complete(struct s3c24xx_i2c *i2c, int ret)
 {
 	dev_dbg(i2c->dev, "master_complete %d\n", 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 inline void s3c24xx_i2c_disable_ack(struct s3c24xx_i2c *i2c)
 {
 	unsigned long tmp;

 	tmp = readl(i2c->regs + S3C2410_IICCON);
 	writel(tmp & ~S3C2410_IICCON_ACKEN, i2c->regs + S3C2410_IICCON);

 }

 static inline void s3c24xx_i2c_enable_ack(struct s3c24xx_i2c *i2c)
 {
 	unsigned long tmp;

 	tmp = readl(i2c->regs + S3C2410_IICCON);
 	writel(tmp | S3C2410_IICCON_ACKEN, i2c->regs + S3C2410_IICCON);

 }

 /* irq enable/disable functions */

 static inline void s3c24xx_i2c_disable_irq(struct s3c24xx_i2c *i2c)
 {
 	unsigned long tmp;

 	tmp = readl(i2c->regs + S3C2410_IICCON);
 	writel(tmp & ~S3C2410_IICCON_IRQEN, i2c->regs + S3C2410_IICCON);
 }

 static inline void s3c24xx_i2c_enable_irq(struct s3c24xx_i2c *i2c)
 {
 	unsigned long tmp;

 	tmp = readl(i2c->regs + S3C2410_IICCON);
 	writel(tmp | S3C2410_IICCON_IRQEN, i2c->regs + S3C2410_IICCON);
 }


 /* s3c24xx_i2c_message_start
  *
  * put the start of a message onto the bus
 */

 static void s3c24xx_i2c_message_start(struct s3c24xx_i2c *i2c,
 				      struct i2c_msg *msg)
 {
 	unsigned int addr = (msg->addr & 0x7f) << 1;
 	unsigned long stat;
 	unsigned long iiccon;

 	stat = 0;
 	stat |=  S3C2410_IICSTAT_TXRXEN;

 	if (msg->flags & I2C_M_RD) {
 		stat |= S3C2410_IICSTAT_MASTER_RX;
 		addr |= 1;
 	} else
 		stat |= S3C2410_IICSTAT_MASTER_TX;

 	if (msg->flags & I2C_M_REV_DIR_ADDR)
 		addr ^= 1;

 	// todo - check for wether ack wanted or not
 	s3c24xx_i2c_enable_ack(i2c);

 	iiccon = readl(i2c->regs + S3C2410_IICCON);
 	writel(stat, i2c->regs + S3C2410_IICSTAT);

 	dev_dbg(i2c->dev, "START: %08lx to IICSTAT, %02x to DS\n", stat, addr);
 	writeb(addr, i2c->regs + S3C2410_IICDS);

 	// delay a bit and reset iiccon before setting start (per samsung)
 	udelay(1);
 	dev_dbg(i2c->dev, "iiccon, %08lx\n", iiccon);
 	writel(iiccon, i2c->regs + S3C2410_IICCON);

 	stat |=  S3C2410_IICSTAT_START;
 	writel(stat, i2c->regs + S3C2410_IICSTAT);
 }

 static inline void s3c24xx_i2c_stop(struct s3c24xx_i2c *i2c, int ret)
 {
 	unsigned long iicstat = readl(i2c->regs + S3C2410_IICSTAT);

 	dev_dbg(i2c->dev, "STOP\n");

 	/* stop the transfer */
 	iicstat &= ~ S3C2410_IICSTAT_START;
 	writel(iicstat, i2c->regs + S3C2410_IICSTAT);

 	i2c->state = STATE_STOP;

 	s3c24xx_i2c_master_complete(i2c, ret);
 	s3c24xx_i2c_disable_irq(i2c);
 }

 /* helper functions to determine the current state in the set of
  * messages we are sending */

 /* is_lastmsg()
  *
  * returns TRUE if the current message is the last in the set
 */

 static inline int is_lastmsg(struct s3c24xx_i2c *i2c)
 {
 	return i2c->msg_idx >= (i2c->msg_num - 1);
 }

 /* is_msglast
  *
  * returns TRUE if we this is the last byte in the current message
 */

 static inline int is_msglast(struct s3c24xx_i2c *i2c)
 {
 	return i2c->msg_ptr == i2c->msg->len-1;
 }

 /* is_msgend
  *
  * returns TRUE if we reached the end of the current message
 */

 static inline int is_msgend(struct s3c24xx_i2c *i2c)
 {
 	return i2c->msg_ptr >= i2c->msg->len;
 }

 /* i2s_s3c_irq_nextbyte
  *
  * process an interrupt and work out what to do
  */

 static int i2s_s3c_irq_nextbyte(struct s3c24xx_i2c *i2c, unsigned long iicstat)
 {
 	unsigned long tmp;
 	unsigned char byte;
 	int ret = 0;

 	switch (i2c->state) {

 	case STATE_IDLE:
 		dev_err(i2c->dev, "%s: called in STATE_IDLE\n", __FUNCTION__);
 		goto out;
 		break;

 	case STATE_STOP:
 		dev_err(i2c->dev, "%s: called in STATE_STOP\n", __FUNCTION__);
 		s3c24xx_i2c_disable_irq(i2c);
 		goto out_ack;

 	case STATE_START:
 		/* last thing we did was send a start condition on the
 		 * bus, or started a new i2c message
 		 */

 		if (iicstat  & S3C2410_IICSTAT_LASTBIT &&
 		    !(i2c->msg->flags & I2C_M_IGNORE_NAK)) {
 			/* ack was not received... */

 			dev_dbg(i2c->dev, "ack was not received\n");
 			s3c24xx_i2c_stop(i2c, -EREMOTEIO);
 			goto out_ack;
 		}

 		if (i2c->msg->flags & I2C_M_RD)
 			i2c->state = STATE_READ;
 		else
 			i2c->state = STATE_WRITE;

 		/* terminate the transfer if there is nothing to do
 		 * (used by the i2c probe to find devices */

 		if (is_lastmsg(i2c) && i2c->msg->len == 0) {
 			s3c24xx_i2c_stop(i2c, 0);
 			goto out_ack;
 		}

 		if (i2c->state == STATE_READ)
 			goto prepare_read;

 		/* fall through to the write state, as we will need to
 		 * send a byte as well */

 	case STATE_WRITE:
 		/* we are writing data to the device... check for the
 		 * end of the message, and if so, work out what to do
 		 */

 	retry_write:
 		if (!is_msgend(i2c)) {
 			byte = i2c->msg->buf[i2c->msg_ptr++];
 			writeb(byte, i2c->regs + S3C2410_IICDS);

 		} else if (!is_lastmsg(i2c)) {
 			/* we need to go to the next i2c message */

 			dev_dbg(i2c->dev, "WRITE: Next Message\n");

 			i2c->msg_ptr = 0;
 			i2c->msg_idx ++;
 			i2c->msg++;

 			/* check to see if we need to do another message */
 			if (i2c->msg->flags & I2C_M_NOSTART) {

 				if (i2c->msg->flags & I2C_M_RD) {
 					/* cannot do this, the controller
 					 * forces us to send a new START
 					 * when we change direction */

 					s3c24xx_i2c_stop(i2c, -EINVAL);
 				}

 				goto retry_write;
 			} else {

 				/* send the new start */
 				s3c24xx_i2c_message_start(i2c, i2c->msg);
 				i2c->state = STATE_START;
 			}

 		} else {
 			/* send stop */

 			s3c24xx_i2c_stop(i2c, 0);
 		}
 		break;

 	case STATE_READ:
 		/* we have a byte of data in the data register, do
 		 * something with it, and then work out wether we are
 		 * going to do any more read/write
 		 */

 		if (!(i2c->msg->flags & I2C_M_IGNORE_NAK) &&
 		    !(is_msglast(i2c) && is_lastmsg(i2c))) {

 			if (iicstat & S3C2410_IICSTAT_LASTBIT) {
 				dev_dbg(i2c->dev, "READ: No Ack\n");

 				s3c24xx_i2c_stop(i2c, -ECONNREFUSED);
 				goto out_ack;
 			}
 		}

 		byte = readb(i2c->regs + S3C2410_IICDS);
 		i2c->msg->buf[i2c->msg_ptr++] = byte;

 	prepare_read:
 		if (is_msglast(i2c)) {
 			/* last byte of buffer */

 			if (is_lastmsg(i2c))
 				s3c24xx_i2c_disable_ack(i2c);

 		} else if (is_msgend(i2c)) {
 			/* ok, we've read the entire buffer, see if there
 			 * is anything else we need to do */

 			if (is_lastmsg(i2c)) {
 				/* last message, send stop and complete */
 				dev_dbg(i2c->dev, "READ: Send Stop\n");

 				s3c24xx_i2c_stop(i2c, 0);
 			} else {
 				/* go to the next transfer */
 				dev_dbg(i2c->dev, "READ: Next Transfer\n");

 				i2c->msg_ptr = 0;
 				i2c->msg_idx++;
 				i2c->msg++;
 			}
 		}

 		break;
 	}

 	/* acknowlegde the IRQ and get back on with the work */

  out_ack:
 	tmp = readl(i2c->regs + S3C2410_IICCON);
 	tmp &= ~S3C2410_IICCON_IRQPEND;
 	writel(tmp, i2c->regs + S3C2410_IICCON);
  out:
 	return ret;
 }

 /* s3c24xx_i2c_irq
  *
  * top level IRQ servicing routine
 */

 static irqreturn_t s3c24xx_i2c_irq(int irqno, void *dev_id)
 {
 	struct s3c24xx_i2c *i2c = dev_id;
 	unsigned long status;
 	unsigned long tmp;

 	status = readl(i2c->regs + S3C2410_IICSTAT);

 	if (status & S3C2410_IICSTAT_ARBITR) {
 		// deal with arbitration loss
 		dev_err(i2c->dev, "deal with arbitration loss\n");
 	}

 	if (i2c->state == STATE_IDLE) {
 		dev_dbg(i2c->dev, "IRQ: error i2c->state == IDLE\n");

 		tmp = readl(i2c->regs + S3C2410_IICCON);
 		tmp &= ~S3C2410_IICCON_IRQPEND;
 		writel(tmp, i2c->regs +  S3C2410_IICCON);
 		goto out;
 	}

 	/* pretty much this leaves us with the fact that we've
 	 * transmitted or received whatever byte we last sent */

 	i2s_s3c_irq_nextbyte(i2c, status);

  out:
 	return IRQ_HANDLED;
 }


 /* s3c24xx_i2c_set_master
  *
  * get the i2c bus for a master transaction
 */

 static int s3c24xx_i2c_set_master(struct s3c24xx_i2c *i2c)
 {
 	unsigned long iicstat;
 	int timeout = 400;

 	while (timeout-- > 0) {
 		iicstat = readl(i2c->regs + S3C2410_IICSTAT);

 		if (!(iicstat & S3C2410_IICSTAT_BUSBUSY))
 			return 0;

 		msleep(1);
 	}

 	dev_dbg(i2c->dev, "timeout: GPEDAT is %08x\n",
 		__raw_readl(S3C2410_GPEDAT));

 	return -ETIMEDOUT;
 }

 /* s3c24xx_i2c_doxfer
  *
  * this starts an i2c transfer
 */

 static int s3c24xx_i2c_doxfer(struct s3c24xx_i2c *i2c, struct i2c_msg *msgs, int num)
 {
 	unsigned long timeout;
 	int ret;

 	ret = s3c24xx_i2c_set_master(i2c);
 	if (ret != 0) {
 		dev_err(i2c->dev, "cannot get bus (error %d)\n", ret);
 		ret = -EAGAIN;
 		goto out;
 	}

 	spin_lock_irq(&i2c->lock);

 	i2c->msg     = msgs;
 	i2c->msg_num = num;
 	i2c->msg_ptr = 0;
 	i2c->msg_idx = 0;
 	i2c->state   = STATE_START;

 	s3c24xx_i2c_enable_irq(i2c);
 	s3c24xx_i2c_message_start(i2c, msgs);
 	spin_unlock_irq(&i2c->lock);

 	timeout = wait_event_timeout(i2c->wait, i2c->msg_num == 0, HZ * 5);

 	ret = i2c->msg_idx;

 	/* having these next two as dev_err() makes life very
 	 * noisy when doing an i2cdetect */

 	if (timeout == 0)
 		dev_dbg(i2c->dev, "timeout\n");
 	else if (ret != num)
 		dev_dbg(i2c->dev, "incomplete xfer (%d)\n", ret);

 	/* ensure the stop has been through the bus */

 	msleep(1);

  out:
 	return ret;
 }

 /* s3c24xx_i2c_xfer
  *
  * first port of call from the i2c bus code when an message needs
  * transferring across the i2c bus.
 */

 static int s3c24xx_i2c_xfer(struct i2c_adapter *adap,
 			struct i2c_msg *msgs, int num)
 {
 	struct s3c24xx_i2c *i2c = (struct s3c24xx_i2c *)adap->algo_data;
 	int retry;
 	int ret;

 	for (retry = 0; retry < adap->retries; retry++) {

 		ret = s3c24xx_i2c_doxfer(i2c, msgs, num);

 		if (ret != -EAGAIN)
 			return ret;

 		dev_dbg(i2c->dev, "Retrying transmission (%d)\n", retry);

 		udelay(100);
 	}

 	return -EREMOTEIO;
 }

 /* declare our i2c functionality */
 static u32 s3c24xx_i2c_func(struct i2c_adapter *adap)
 {
 	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_PROTOCOL_MANGLING;
 }

 /* i2c bus registration info */

 static const struct i2c_algorithm s3c24xx_i2c_algorithm = {
 	.master_xfer		= s3c24xx_i2c_xfer,
 	.functionality		= s3c24xx_i2c_func,
 };

 static struct s3c24xx_i2c s3c24xx_i2c = {
 	.lock	= SPIN_LOCK_UNLOCKED,
 	.wait	= __WAIT_QUEUE_HEAD_INITIALIZER(s3c24xx_i2c.wait),
 	.adap	= {
 		.name			= "s3c2410-i2c",
 		.owner			= THIS_MODULE,
 		.algo			= &s3c24xx_i2c_algorithm,
 		.retries		= 2,
 		.class			= I2C_CLASS_HWMON,
 	},
 };

 /* s3c24xx_i2c_calcdivisor
  *
  * return the divisor settings for a given frequency
 */

 static int s3c24xx_i2c_calcdivisor(unsigned long clkin, unsigned int wanted,
 				   unsigned int *div1, unsigned int *divs)
 {
 	unsigned int calc_divs = clkin / wanted;
 	unsigned int calc_div1;

 	if (calc_divs > (16*16))
 		calc_div1 = 512;
 	else
 		calc_div1 = 16;

 	calc_divs += calc_div1-1;
 	calc_divs /= calc_div1;

 	if (calc_divs == 0)
 		calc_divs = 1;
 	if (calc_divs > 17)
 		calc_divs = 17;

 	*divs = calc_divs;
 	*div1 = calc_div1;

 	return clkin / (calc_divs * calc_div1);
 }

 /* freq_acceptable
  *
  * test wether a frequency is within the acceptable range of error
 */

 static inline int freq_acceptable(unsigned int freq, unsigned int wanted)
 {
 	int diff = freq - wanted;

 	return (diff >= -2 && diff <= 2);
 }

 /* s3c24xx_i2c_getdivisor
  *
  * work out a divisor for the user requested frequency setting,
  * either by the requested frequency, or scanning the acceptable
  * range of frequencies until something is found
 */

 static int s3c24xx_i2c_getdivisor(struct s3c24xx_i2c *i2c,
 				  struct s3c2410_platform_i2c *pdata,
 				  unsigned long *iicon,
 				  unsigned int *got)
 {
 	unsigned long clkin = clk_get_rate(i2c->clk);

 	unsigned int divs, div1;
 	int freq;
 	int start, end;

 	clkin /= 1000;		/* clkin now in KHz */

 	dev_dbg(i2c->dev,  "pdata %p, freq %lu %lu..%lu\n",
 		 pdata, pdata->bus_freq, pdata->min_freq, pdata->max_freq);

 	if (pdata->bus_freq != 0) {
 		freq = s3c24xx_i2c_calcdivisor(clkin, pdata->bus_freq/1000,
 					       &div1, &divs);
 		if (freq_acceptable(freq, pdata->bus_freq/1000))
 			goto found;
 	}

 	/* ok, we may have to search for something suitable... */

 	start = (pdata->max_freq == 0) ? pdata->bus_freq : pdata->max_freq;
 	end = pdata->min_freq;

 	start /= 1000;
 	end /= 1000;

 	/* search loop... */

 	for (; start > end; start--) {
 		freq = s3c24xx_i2c_calcdivisor(clkin, start, &div1, &divs);
 		if (freq_acceptable(freq, start))
 			goto found;
 	}

 	/* cannot find frequency spec */

 	return -EINVAL;

  found:
 	*got = freq;
 	*iicon |= (divs-1);
 	*iicon |= (div1 == 512) ? S3C2410_IICCON_TXDIV_512 : 0;
 	return 0;
 }

 /* s3c24xx_i2c_init
  *
  * initialise the controller, set the IO lines and frequency
 */

 static int s3c24xx_i2c_init(struct s3c24xx_i2c *i2c)
 {
 	unsigned long iicon = S3C2410_IICCON_IRQEN | S3C2410_IICCON_ACKEN;
 	struct s3c2410_platform_i2c *pdata;
 	unsigned int freq;

 	/* get the plafrom data */

 	pdata = s3c24xx_i2c_get_platformdata(i2c->adap.dev.parent);

 	/* inititalise the gpio */

 	s3c2410_gpio_cfgpin(S3C2410_GPE15, S3C2410_GPE15_IICSDA);
 	s3c2410_gpio_cfgpin(S3C2410_GPE14, S3C2410_GPE14_IICSCL);

 	/* write slave address */

 	writeb(pdata->slave_addr, i2c->regs + S3C2410_IICADD);

 	dev_info(i2c->dev, "slave address 0x%02x\n", pdata->slave_addr);

 	/* we need to work out the divisors for the clock... */

 	if (s3c24xx_i2c_getdivisor(i2c, pdata, &iicon, &freq) != 0) {
 		dev_err(i2c->dev, "cannot meet bus frequency required\n");
 		return -EINVAL;
 	}

 	/* todo - check that the i2c lines aren't being dragged anywhere */

 	dev_info(i2c->dev, "bus frequency set to %d KHz\n", freq);
 	dev_dbg(i2c->dev, "S3C2410_IICCON=0x%02lx\n", iicon);

 	writel(iicon, i2c->regs + S3C2410_IICCON);

 	/* check for s3c2440 i2c controller  */

 	if (s3c24xx_i2c_is2440(i2c)) {
 		dev_dbg(i2c->dev, "S3C2440_IICLC=%08x\n", pdata->sda_delay);

 		writel(pdata->sda_delay, i2c->regs + S3C2440_IICLC);
 	}

 	return 0;
 }

 static void s3c24xx_i2c_free(struct s3c24xx_i2c *i2c)
 {
 	if (i2c->clk != NULL && !IS_ERR(i2c->clk)) {
 		clk_disable(i2c->clk);
 		clk_put(i2c->clk);
 		i2c->clk = NULL;
 	}

 	if (i2c->regs != NULL) {
 		iounmap(i2c->regs);
 		i2c->regs = NULL;
 	}

 	if (i2c->ioarea != NULL) {
 		release_resource(i2c->ioarea);
 		kfree(i2c->ioarea);
 		i2c->ioarea = NULL;
 	}
 }

 /* s3c24xx_i2c_probe
  *
  * called by the bus driver when a suitable device is found
 */

 static int s3c24xx_i2c_probe(struct platform_device *pdev)
 {
 	struct s3c24xx_i2c *i2c = &s3c24xx_i2c;
 	struct resource *res;
 	int ret;

 	/* find the clock and enable it */

 	i2c->dev = &pdev->dev;
 	i2c->clk = clk_get(&pdev->dev, "i2c");
 	if (IS_ERR(i2c->clk)) {
 		dev_err(&pdev->dev, "cannot get clock\n");
 		ret = -ENOENT;
 		goto out;
 	}

 	dev_dbg(&pdev->dev, "clock source %p\n", i2c->clk);

 	clk_enable(i2c->clk);

 	/* map the registers */

 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	if (res == NULL) {
 		dev_err(&pdev->dev, "cannot find IO resource\n");
 		ret = -ENOENT;
 		goto out;
 	}

 	i2c->ioarea = request_mem_region(res->start, (res->end-res->start)+1,
 					 pdev->name);

 	if (i2c->ioarea == NULL) {
 		dev_err(&pdev->dev, "cannot request IO\n");
 		ret = -ENXIO;
 		goto out;
 	}

 	i2c->regs = ioremap(res->start, (res->end-res->start)+1);

 	if (i2c->regs == NULL) {
 		dev_err(&pdev->dev, "cannot map IO\n");
 		ret = -ENXIO;
 		goto out;
 	}

 	dev_dbg(&pdev->dev, "registers %p (%p, %p)\n", i2c->regs, i2c->ioarea, res);

 	/* setup info block for the i2c core */

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

 	/* initialise the i2c controller */

 	ret = s3c24xx_i2c_init(i2c);
 	if (ret != 0)
 		goto out;

 	/* find the IRQ for this unit (note, this relies on the init call to
 	 * ensure no current IRQs pending
 	 */

 	res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 	if (res == NULL) {
 		dev_err(&pdev->dev, "cannot find IRQ\n");
 		ret = -ENOENT;
 		goto out;
 	}

 	ret = request_irq(res->start, s3c24xx_i2c_irq, IRQF_DISABLED,
 			  pdev->name, i2c);

 	if (ret != 0) {
 		dev_err(&pdev->dev, "cannot claim IRQ\n");
 		goto out;
 	}

 	i2c->irq = res;

 	dev_dbg(&pdev->dev, "irq resource %p (%ld)\n", res, res->start);

 	ret = i2c_add_adapter(&i2c->adap);
 	if (ret < 0) {
 		dev_err(&pdev->dev, "failed to add bus to i2c core\n");
 		goto out;
 	}

 	platform_set_drvdata(pdev, i2c);

 	dev_info(&pdev->dev, "%s: S3C I2C adapter\n", i2c->adap.dev.bus_id);

  out:
 	if (ret < 0)
 		s3c24xx_i2c_free(i2c);

 	return ret;
 }

 /* s3c24xx_i2c_remove
  *
  * called when device is removed from the bus
 */

 static int s3c24xx_i2c_remove(struct platform_device *pdev)
 {
 	struct s3c24xx_i2c *i2c = platform_get_drvdata(pdev);

 	if (i2c != NULL) {
 		s3c24xx_i2c_free(i2c);
 		platform_set_drvdata(pdev, NULL);
 	}

 	return 0;
 }

 #ifdef CONFIG_PM
 static int s3c24xx_i2c_resume(struct platform_device *dev)
 {
 	struct s3c24xx_i2c *i2c = platform_get_drvdata(dev);

 	if (i2c != NULL)
 		s3c24xx_i2c_init(i2c);

 	return 0;
 }

 #else
 #define s3c24xx_i2c_resume NULL
 #endif

 /* device driver for platform bus bits */

 static struct platform_driver s3c2410_i2c_driver = {
 	.probe		= s3c24xx_i2c_probe,
 	.remove		= s3c24xx_i2c_remove,
 	.resume		= s3c24xx_i2c_resume,
 	.driver		= {
 		.owner	= THIS_MODULE,
 		.name	= "s3c2410-i2c",
 	},
 };

 static struct platform_driver s3c2440_i2c_driver = {
 	.probe		= s3c24xx_i2c_probe,
 	.remove		= s3c24xx_i2c_remove,
 	.resume		= s3c24xx_i2c_resume,
 	.driver		= {
 		.owner	= THIS_MODULE,
 		.name	= "s3c2440-i2c",
 	},
 };

 static int __init i2c_adap_s3c_init(void)
 {
 	int ret;

 	ret = platform_driver_register(&s3c2410_i2c_driver);
 	if (ret == 0) {
 		ret = platform_driver_register(&s3c2440_i2c_driver);
 		if (ret)
 			platform_driver_unregister(&s3c2410_i2c_driver);
 	}

 	return ret;
 }

 static void __exit i2c_adap_s3c_exit(void)
 {
 	platform_driver_unregister(&s3c2410_i2c_driver);
 	platform_driver_unregister(&s3c2440_i2c_driver);
 }

 module_init(i2c_adap_s3c_init);
 module_exit(i2c_adap_s3c_exit);

 MODULE_DESCRIPTION("S3C24XX I2C Bus driver");
 MODULE_AUTHOR("Ben Dooks, <ben@simtec.co.uk>");
 MODULE_LICENSE("GPL");
	/* linux/drivers/i2c/busses/i2c-s3c2410.c
	*
	* Copyright (C) 2004,2005 Simtec Electronics
	* Ben Dooks <ben@simtec.co.uk>
	*
	* S3C2410 I2C Controller
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program; if not, write to the Free Software
	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
	*/

	#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/interrupt.h>
	#include <linux/delay.h>
	#include <linux/errno.h>
	#include <linux/err.h>
	#include <linux/platform_device.h>
	#include <linux/clk.h>

	#include <asm/hardware.h>
	#include <asm/irq.h>
	#include <asm/io.h>

	#include <asm/arch/regs-gpio.h>
	#include <asm/arch/regs-iic.h>
	#include <asm/arch/iic.h>

	/* i2c controller state */

	enum s3c24xx_i2c_state {
	STATE_IDLE,
	STATE_START,
	STATE_READ,
	STATE_WRITE,
	STATE_STOP
	};

	struct s3c24xx_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;

	enum s3c24xx_i2c_state state;

	void __iomem *regs;
	struct clk *clk;
	struct device *dev;
	struct resource *irq;
	struct resource *ioarea;
	struct i2c_adapter adap;
	};

	/* default platform data to use if not supplied in the platform_device
	*/

	static struct s3c2410_platform_i2c s3c24xx_i2c_default_platform = {
	.flags = 0,
	.slave_addr = 0x10,
	.bus_freq = 100*1000,
	.max_freq = 400*1000,
	.sda_delay = S3C2410_IICLC_SDA_DELAY5 \| S3C2410_IICLC_FILTER_ON,
	};

	/* s3c24xx_i2c_is2440()
	*
	* return true is this is an s3c2440
	*/

	static inline int s3c24xx_i2c_is2440(struct s3c24xx_i2c *i2c)
	{
	struct platform_device *pdev = to_platform_device(i2c->dev);

	return !strcmp(pdev->name, "s3c2440-i2c");
	}


	/* s3c24xx_i2c_get_platformdata
	*
	* get the platform data associated with the given device, or return
	* the default if there is none
	*/

	static inline struct s3c2410_platform_i2c s3c24xx_i2c_get_platformdata(struct device dev)
	{
	if (dev->platform_data != NULL)
	return (struct s3c2410_platform_i2c *)dev->platform_data;

	return &s3c24xx_i2c_default_platform;
	}

	/* s3c24xx_i2c_master_complete
	*
	* complete the message and wake up the caller, using the given return code,
	* or zero to mean ok.
	*/

	static inline void s3c24xx_i2c_master_complete(struct s3c24xx_i2c *i2c, int ret)
	{
	dev_dbg(i2c->dev, "master_complete %d\n", 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 inline void s3c24xx_i2c_disable_ack(struct s3c24xx_i2c *i2c)
	{
	unsigned long tmp;

	tmp = readl(i2c->regs + S3C2410_IICCON);
	writel(tmp & ~S3C2410_IICCON_ACKEN, i2c->regs + S3C2410_IICCON);

	}

	static inline void s3c24xx_i2c_enable_ack(struct s3c24xx_i2c *i2c)
	{
	unsigned long tmp;

	tmp = readl(i2c->regs + S3C2410_IICCON);
	writel(tmp \| S3C2410_IICCON_ACKEN, i2c->regs + S3C2410_IICCON);

	}

	/* irq enable/disable functions */

	static inline void s3c24xx_i2c_disable_irq(struct s3c24xx_i2c *i2c)
	{
	unsigned long tmp;

	tmp = readl(i2c->regs + S3C2410_IICCON);
	writel(tmp & ~S3C2410_IICCON_IRQEN, i2c->regs + S3C2410_IICCON);
	}

	static inline void s3c24xx_i2c_enable_irq(struct s3c24xx_i2c *i2c)
	{
	unsigned long tmp;

	tmp = readl(i2c->regs + S3C2410_IICCON);
	writel(tmp \| S3C2410_IICCON_IRQEN, i2c->regs + S3C2410_IICCON);
	}


	/* s3c24xx_i2c_message_start
	*
	* put the start of a message onto the bus
	*/

	static void s3c24xx_i2c_message_start(struct s3c24xx_i2c *i2c,
	struct i2c_msg *msg)
	{
	unsigned int addr = (msg->addr & 0x7f) << 1;
	unsigned long stat;
	unsigned long iiccon;

	stat = 0;
	stat \|= S3C2410_IICSTAT_TXRXEN;

	if (msg->flags & I2C_M_RD) {
	stat \|= S3C2410_IICSTAT_MASTER_RX;
	addr \|= 1;
	} else
	stat \|= S3C2410_IICSTAT_MASTER_TX;

	if (msg->flags & I2C_M_REV_DIR_ADDR)
	addr ^= 1;

	// todo - check for wether ack wanted or not
	s3c24xx_i2c_enable_ack(i2c);

	iiccon = readl(i2c->regs + S3C2410_IICCON);
	writel(stat, i2c->regs + S3C2410_IICSTAT);

	dev_dbg(i2c->dev, "START: %08lx to IICSTAT, %02x to DS\n", stat, addr);
	writeb(addr, i2c->regs + S3C2410_IICDS);

	// delay a bit and reset iiccon before setting start (per samsung)
	udelay(1);
	dev_dbg(i2c->dev, "iiccon, %08lx\n", iiccon);
	writel(iiccon, i2c->regs + S3C2410_IICCON);

	stat \|= S3C2410_IICSTAT_START;
	writel(stat, i2c->regs + S3C2410_IICSTAT);
	}

	static inline void s3c24xx_i2c_stop(struct s3c24xx_i2c *i2c, int ret)
	{
	unsigned long iicstat = readl(i2c->regs + S3C2410_IICSTAT);

	dev_dbg(i2c->dev, "STOP\n");

	/* stop the transfer */
	iicstat &= ~ S3C2410_IICSTAT_START;
	writel(iicstat, i2c->regs + S3C2410_IICSTAT);

	i2c->state = STATE_STOP;

	s3c24xx_i2c_master_complete(i2c, ret);
	s3c24xx_i2c_disable_irq(i2c);
	}

	/* helper functions to determine the current state in the set of
	* messages we are sending */

	/* is_lastmsg()
	*
	* returns TRUE if the current message is the last in the set
	*/

	static inline int is_lastmsg(struct s3c24xx_i2c *i2c)
	{
	return i2c->msg_idx >= (i2c->msg_num - 1);
	}

	/* is_msglast
	*
	* returns TRUE if we this is the last byte in the current message
	*/

	static inline int is_msglast(struct s3c24xx_i2c *i2c)
	{
	return i2c->msg_ptr == i2c->msg->len-1;
	}

	/* is_msgend
	*
	* returns TRUE if we reached the end of the current message
	*/

	static inline int is_msgend(struct s3c24xx_i2c *i2c)
	{
	return i2c->msg_ptr >= i2c->msg->len;
	}

	/* i2s_s3c_irq_nextbyte
	*
	* process an interrupt and work out what to do
	*/

	static int i2s_s3c_irq_nextbyte(struct s3c24xx_i2c *i2c, unsigned long iicstat)
	{
	unsigned long tmp;
	unsigned char byte;
	int ret = 0;

	switch (i2c->state) {

	case STATE_IDLE:
	dev_err(i2c->dev, "%s: called in STATE_IDLE\n", __FUNCTION__);
	goto out;
	break;

	case STATE_STOP:
	dev_err(i2c->dev, "%s: called in STATE_STOP\n", __FUNCTION__);
	s3c24xx_i2c_disable_irq(i2c);
	goto out_ack;

	case STATE_START:
	/* last thing we did was send a start condition on the
	* bus, or started a new i2c message
	*/

	if (iicstat & S3C2410_IICSTAT_LASTBIT &&
	!(i2c->msg->flags & I2C_M_IGNORE_NAK)) {
	/* ack was not received... */

	dev_dbg(i2c->dev, "ack was not received\n");
	s3c24xx_i2c_stop(i2c, -EREMOTEIO);
	goto out_ack;
	}

	if (i2c->msg->flags & I2C_M_RD)
	i2c->state = STATE_READ;
	else
	i2c->state = STATE_WRITE;

	/* terminate the transfer if there is nothing to do
	* (used by the i2c probe to find devices */

	if (is_lastmsg(i2c) && i2c->msg->len == 0) {
	s3c24xx_i2c_stop(i2c, 0);
	goto out_ack;
	}

	if (i2c->state == STATE_READ)
	goto prepare_read;

	/* fall through to the write state, as we will need to
	* send a byte as well */

	case STATE_WRITE:
	/* we are writing data to the device... check for the
	* end of the message, and if so, work out what to do
	*/

	retry_write:
	if (!is_msgend(i2c)) {
	byte = i2c->msg->buf[i2c->msg_ptr++];
	writeb(byte, i2c->regs + S3C2410_IICDS);

	} else if (!is_lastmsg(i2c)) {
	/* we need to go to the next i2c message */

	dev_dbg(i2c->dev, "WRITE: Next Message\n");

	i2c->msg_ptr = 0;
	i2c->msg_idx ++;
	i2c->msg++;

	/* check to see if we need to do another message */
	if (i2c->msg->flags & I2C_M_NOSTART) {

	if (i2c->msg->flags & I2C_M_RD) {
	/* cannot do this, the controller
	* forces us to send a new START
	* when we change direction */

	s3c24xx_i2c_stop(i2c, -EINVAL);
	}

	goto retry_write;
	} else {

	/* send the new start */
	s3c24xx_i2c_message_start(i2c, i2c->msg);
	i2c->state = STATE_START;
	}

	} else {
	/* send stop */

	s3c24xx_i2c_stop(i2c, 0);
	}
	break;

	case STATE_READ:
	/* we have a byte of data in the data register, do
	* something with it, and then work out wether we are
	* going to do any more read/write
	*/

	if (!(i2c->msg->flags & I2C_M_IGNORE_NAK) &&
	!(is_msglast(i2c) && is_lastmsg(i2c))) {

	if (iicstat & S3C2410_IICSTAT_LASTBIT) {
	dev_dbg(i2c->dev, "READ: No Ack\n");

	s3c24xx_i2c_stop(i2c, -ECONNREFUSED);
	goto out_ack;
	}
	}

	byte = readb(i2c->regs + S3C2410_IICDS);
	i2c->msg->buf[i2c->msg_ptr++] = byte;

	prepare_read:
	if (is_msglast(i2c)) {
	/* last byte of buffer */

	if (is_lastmsg(i2c))
	s3c24xx_i2c_disable_ack(i2c);

	} else if (is_msgend(i2c)) {
	/* ok, we've read the entire buffer, see if there
	* is anything else we need to do */

	if (is_lastmsg(i2c)) {
	/* last message, send stop and complete */
	dev_dbg(i2c->dev, "READ: Send Stop\n");

	s3c24xx_i2c_stop(i2c, 0);
	} else {
	/* go to the next transfer */
	dev_dbg(i2c->dev, "READ: Next Transfer\n");

	i2c->msg_ptr = 0;
	i2c->msg_idx++;
	i2c->msg++;
	}
	}

	break;
	}

	/* acknowlegde the IRQ and get back on with the work */

	out_ack:
	tmp = readl(i2c->regs + S3C2410_IICCON);
	tmp &= ~S3C2410_IICCON_IRQPEND;
	writel(tmp, i2c->regs + S3C2410_IICCON);
	out:
	return ret;
	}

	/* s3c24xx_i2c_irq
	*
	* top level IRQ servicing routine
	*/

	static irqreturn_t s3c24xx_i2c_irq(int irqno, void *dev_id)
	{
	struct s3c24xx_i2c *i2c = dev_id;
	unsigned long status;
	unsigned long tmp;

	status = readl(i2c->regs + S3C2410_IICSTAT);

	if (status & S3C2410_IICSTAT_ARBITR) {
	// deal with arbitration loss
	dev_err(i2c->dev, "deal with arbitration loss\n");
	}

	if (i2c->state == STATE_IDLE) {
	dev_dbg(i2c->dev, "IRQ: error i2c->state == IDLE\n");

	tmp = readl(i2c->regs + S3C2410_IICCON);
	tmp &= ~S3C2410_IICCON_IRQPEND;
	writel(tmp, i2c->regs + S3C2410_IICCON);
	goto out;
	}

	/* pretty much this leaves us with the fact that we've
	* transmitted or received whatever byte we last sent */

	i2s_s3c_irq_nextbyte(i2c, status);

	out:
	return IRQ_HANDLED;
	}


	/* s3c24xx_i2c_set_master
	*
	* get the i2c bus for a master transaction
	*/

	static int s3c24xx_i2c_set_master(struct s3c24xx_i2c *i2c)
	{
	unsigned long iicstat;
	int timeout = 400;

	while (timeout-- > 0) {
	iicstat = readl(i2c->regs + S3C2410_IICSTAT);

	if (!(iicstat & S3C2410_IICSTAT_BUSBUSY))
	return 0;

	msleep(1);
	}

	dev_dbg(i2c->dev, "timeout: GPEDAT is %08x\n",
	__raw_readl(S3C2410_GPEDAT));

	return -ETIMEDOUT;
	}

	/* s3c24xx_i2c_doxfer
	*
	* this starts an i2c transfer
	*/

	static int s3c24xx_i2c_doxfer(struct s3c24xx_i2c i2c, struct i2c_msg msgs, int num)
	{
	unsigned long timeout;
	int ret;

	ret = s3c24xx_i2c_set_master(i2c);
	if (ret != 0) {
	dev_err(i2c->dev, "cannot get bus (error %d)\n", ret);
	ret = -EAGAIN;
	goto out;
	}

	spin_lock_irq(&i2c->lock);

	i2c->msg = msgs;
	i2c->msg_num = num;
	i2c->msg_ptr = 0;
	i2c->msg_idx = 0;
	i2c->state = STATE_START;

	s3c24xx_i2c_enable_irq(i2c);
	s3c24xx_i2c_message_start(i2c, msgs);
	spin_unlock_irq(&i2c->lock);

	timeout = wait_event_timeout(i2c->wait, i2c->msg_num == 0, HZ * 5);

	ret = i2c->msg_idx;

	/* having these next two as dev_err() makes life very
	* noisy when doing an i2cdetect */

	if (timeout == 0)
	dev_dbg(i2c->dev, "timeout\n");
	else if (ret != num)
	dev_dbg(i2c->dev, "incomplete xfer (%d)\n", ret);

	/* ensure the stop has been through the bus */

	msleep(1);

	out:
	return ret;
	}

	/* s3c24xx_i2c_xfer
	*
	* first port of call from the i2c bus code when an message needs
	* transferring across the i2c bus.
	*/

	static int s3c24xx_i2c_xfer(struct i2c_adapter *adap,
	struct i2c_msg *msgs, int num)
	{
	struct s3c24xx_i2c i2c = (struct s3c24xx_i2c )adap->algo_data;
	int retry;
	int ret;

	for (retry = 0; retry < adap->retries; retry++) {

	ret = s3c24xx_i2c_doxfer(i2c, msgs, num);

	if (ret != -EAGAIN)
	return ret;

	dev_dbg(i2c->dev, "Retrying transmission (%d)\n", retry);

	udelay(100);
	}

	return -EREMOTEIO;
	}

	/* declare our i2c functionality */
	static u32 s3c24xx_i2c_func(struct i2c_adapter *adap)
	{
	return I2C_FUNC_I2C \| I2C_FUNC_SMBUS_EMUL \| I2C_FUNC_PROTOCOL_MANGLING;
	}

	/* i2c bus registration info */

	static const struct i2c_algorithm s3c24xx_i2c_algorithm = {
	.master_xfer = s3c24xx_i2c_xfer,
	.functionality = s3c24xx_i2c_func,
	};

	static struct s3c24xx_i2c s3c24xx_i2c = {
	.lock = SPIN_LOCK_UNLOCKED,
	.wait = __WAIT_QUEUE_HEAD_INITIALIZER(s3c24xx_i2c.wait),
	.adap = {
	.name = "s3c2410-i2c",
	.owner = THIS_MODULE,
	.algo = &s3c24xx_i2c_algorithm,
	.retries = 2,
	.class = I2C_CLASS_HWMON,
	},
	};

	/* s3c24xx_i2c_calcdivisor
	*
	* return the divisor settings for a given frequency
	*/

	static int s3c24xx_i2c_calcdivisor(unsigned long clkin, unsigned int wanted,
	unsigned int div1, unsigned int divs)
	{
	unsigned int calc_divs = clkin / wanted;
	unsigned int calc_div1;

	if (calc_divs > (16*16))
	calc_div1 = 512;
	else
	calc_div1 = 16;

	calc_divs += calc_div1-1;
	calc_divs /= calc_div1;

	if (calc_divs == 0)
	calc_divs = 1;
	if (calc_divs > 17)
	calc_divs = 17;

	*divs = calc_divs;
	*div1 = calc_div1;

	return clkin / (calc_divs * calc_div1);
	}

	/* freq_acceptable
	*
	* test wether a frequency is within the acceptable range of error
	*/

	static inline int freq_acceptable(unsigned int freq, unsigned int wanted)
	{
	int diff = freq - wanted;

	return (diff >= -2 && diff <= 2);
	}

	/* s3c24xx_i2c_getdivisor
	*
	* work out a divisor for the user requested frequency setting,
	* either by the requested frequency, or scanning the acceptable
	* range of frequencies until something is found
	*/

	static int s3c24xx_i2c_getdivisor(struct s3c24xx_i2c *i2c,
	struct s3c2410_platform_i2c *pdata,
	unsigned long *iicon,
	unsigned int *got)
	{
	unsigned long clkin = clk_get_rate(i2c->clk);

	unsigned int divs, div1;
	int freq;
	int start, end;

	clkin /= 1000; /* clkin now in KHz */

	dev_dbg(i2c->dev, "pdata %p, freq %lu %lu..%lu\n",
	pdata, pdata->bus_freq, pdata->min_freq, pdata->max_freq);

	if (pdata->bus_freq != 0) {
	freq = s3c24xx_i2c_calcdivisor(clkin, pdata->bus_freq/1000,
	&div1, &divs);
	if (freq_acceptable(freq, pdata->bus_freq/1000))
	goto found;
	}

	/* ok, we may have to search for something suitable... */

	start = (pdata->max_freq == 0) ? pdata->bus_freq : pdata->max_freq;
	end = pdata->min_freq;

	start /= 1000;
	end /= 1000;

	/* search loop... */

	for (; start > end; start--) {
	freq = s3c24xx_i2c_calcdivisor(clkin, start, &div1, &divs);
	if (freq_acceptable(freq, start))
	goto found;
	}

	/* cannot find frequency spec */

	return -EINVAL;

	found:
	*got = freq;
	*iicon \|= (divs-1);
	*iicon \|= (div1 == 512) ? S3C2410_IICCON_TXDIV_512 : 0;
	return 0;
	}

	/* s3c24xx_i2c_init
	*
	* initialise the controller, set the IO lines and frequency
	*/

	static int s3c24xx_i2c_init(struct s3c24xx_i2c *i2c)
	{
	unsigned long iicon = S3C2410_IICCON_IRQEN \| S3C2410_IICCON_ACKEN;
	struct s3c2410_platform_i2c *pdata;
	unsigned int freq;

	/* get the plafrom data */

	pdata = s3c24xx_i2c_get_platformdata(i2c->adap.dev.parent);

	/* inititalise the gpio */

	s3c2410_gpio_cfgpin(S3C2410_GPE15, S3C2410_GPE15_IICSDA);
	s3c2410_gpio_cfgpin(S3C2410_GPE14, S3C2410_GPE14_IICSCL);

	/* write slave address */

	writeb(pdata->slave_addr, i2c->regs + S3C2410_IICADD);

	dev_info(i2c->dev, "slave address 0x%02x\n", pdata->slave_addr);

	/* we need to work out the divisors for the clock... */

	if (s3c24xx_i2c_getdivisor(i2c, pdata, &iicon, &freq) != 0) {
	dev_err(i2c->dev, "cannot meet bus frequency required\n");
	return -EINVAL;
	}

	/* todo - check that the i2c lines aren't being dragged anywhere */

	dev_info(i2c->dev, "bus frequency set to %d KHz\n", freq);
	dev_dbg(i2c->dev, "S3C2410_IICCON=0x%02lx\n", iicon);

	writel(iicon, i2c->regs + S3C2410_IICCON);

	/* check for s3c2440 i2c controller */

	if (s3c24xx_i2c_is2440(i2c)) {
	dev_dbg(i2c->dev, "S3C2440_IICLC=%08x\n", pdata->sda_delay);

	writel(pdata->sda_delay, i2c->regs + S3C2440_IICLC);
	}

	return 0;
	}

	static void s3c24xx_i2c_free(struct s3c24xx_i2c *i2c)
	{
	if (i2c->clk != NULL && !IS_ERR(i2c->clk)) {
	clk_disable(i2c->clk);
	clk_put(i2c->clk);
	i2c->clk = NULL;
	}

	if (i2c->regs != NULL) {
	iounmap(i2c->regs);
	i2c->regs = NULL;
	}

	if (i2c->ioarea != NULL) {
	release_resource(i2c->ioarea);
	kfree(i2c->ioarea);
	i2c->ioarea = NULL;
	}
	}

	/* s3c24xx_i2c_probe
	*
	* called by the bus driver when a suitable device is found
	*/

	static int s3c24xx_i2c_probe(struct platform_device *pdev)
	{
	struct s3c24xx_i2c *i2c = &s3c24xx_i2c;
	struct resource *res;
	int ret;

	/* find the clock and enable it */

	i2c->dev = &pdev->dev;
	i2c->clk = clk_get(&pdev->dev, "i2c");
	if (IS_ERR(i2c->clk)) {
	dev_err(&pdev->dev, "cannot get clock\n");
	ret = -ENOENT;
	goto out;
	}

	dev_dbg(&pdev->dev, "clock source %p\n", i2c->clk);

	clk_enable(i2c->clk);

	/* map the registers */

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (res == NULL) {
	dev_err(&pdev->dev, "cannot find IO resource\n");
	ret = -ENOENT;
	goto out;
	}

	i2c->ioarea = request_mem_region(res->start, (res->end-res->start)+1,
	pdev->name);

	if (i2c->ioarea == NULL) {
	dev_err(&pdev->dev, "cannot request IO\n");
	ret = -ENXIO;
	goto out;
	}

	i2c->regs = ioremap(res->start, (res->end-res->start)+1);

	if (i2c->regs == NULL) {
	dev_err(&pdev->dev, "cannot map IO\n");
	ret = -ENXIO;
	goto out;
	}

	dev_dbg(&pdev->dev, "registers %p (%p, %p)\n", i2c->regs, i2c->ioarea, res);

	/* setup info block for the i2c core */

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

	/* initialise the i2c controller */

	ret = s3c24xx_i2c_init(i2c);
	if (ret != 0)
	goto out;

	/* find the IRQ for this unit (note, this relies on the init call to
	* ensure no current IRQs pending
	*/

	res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
	if (res == NULL) {
	dev_err(&pdev->dev, "cannot find IRQ\n");
	ret = -ENOENT;
	goto out;
	}

	ret = request_irq(res->start, s3c24xx_i2c_irq, IRQF_DISABLED,
	pdev->name, i2c);

	if (ret != 0) {
	dev_err(&pdev->dev, "cannot claim IRQ\n");
	goto out;
	}

	i2c->irq = res;

	dev_dbg(&pdev->dev, "irq resource %p (%ld)\n", res, res->start);

	ret = i2c_add_adapter(&i2c->adap);
	if (ret < 0) {
	dev_err(&pdev->dev, "failed to add bus to i2c core\n");
	goto out;
	}

	platform_set_drvdata(pdev, i2c);

	dev_info(&pdev->dev, "%s: S3C I2C adapter\n", i2c->adap.dev.bus_id);

	out:
	if (ret < 0)
	s3c24xx_i2c_free(i2c);

	return ret;
	}

	/* s3c24xx_i2c_remove
	*
	* called when device is removed from the bus
	*/

	static int s3c24xx_i2c_remove(struct platform_device *pdev)
	{
	struct s3c24xx_i2c *i2c = platform_get_drvdata(pdev);

	if (i2c != NULL) {
	s3c24xx_i2c_free(i2c);
	platform_set_drvdata(pdev, NULL);
	}

	return 0;
	}

	#ifdef CONFIG_PM
	static int s3c24xx_i2c_resume(struct platform_device *dev)
	{
	struct s3c24xx_i2c *i2c = platform_get_drvdata(dev);

	if (i2c != NULL)
	s3c24xx_i2c_init(i2c);

	return 0;
	}

	#else
	#define s3c24xx_i2c_resume NULL
	#endif

	/* device driver for platform bus bits */

	static struct platform_driver s3c2410_i2c_driver = {
	.probe = s3c24xx_i2c_probe,
	.remove = s3c24xx_i2c_remove,
	.resume = s3c24xx_i2c_resume,
	.driver = {
	.owner = THIS_MODULE,
	.name = "s3c2410-i2c",
	},
	};

	static struct platform_driver s3c2440_i2c_driver = {
	.probe = s3c24xx_i2c_probe,
	.remove = s3c24xx_i2c_remove,
	.resume = s3c24xx_i2c_resume,
	.driver = {
	.owner = THIS_MODULE,
	.name = "s3c2440-i2c",
	},
	};

	static int __init i2c_adap_s3c_init(void)
	{
	int ret;

	ret = platform_driver_register(&s3c2410_i2c_driver);
	if (ret == 0) {
	ret = platform_driver_register(&s3c2440_i2c_driver);
	if (ret)
	platform_driver_unregister(&s3c2410_i2c_driver);
	}

	return ret;
	}

	static void __exit i2c_adap_s3c_exit(void)
	{
	platform_driver_unregister(&s3c2410_i2c_driver);
	platform_driver_unregister(&s3c2440_i2c_driver);
	}

	module_init(i2c_adap_s3c_init);
	module_exit(i2c_adap_s3c_exit);

	MODULE_DESCRIPTION("S3C24XX I2C Bus driver");
	MODULE_AUTHOR("Ben Dooks, <ben@simtec.co.uk>");
	MODULE_LICENSE("GPL");