[PATCH] I2C: S3C2410 I2C Bus driver

Bus driver for the Samsung S3C2410 SoC onboard I2C controller
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>

drivers/i2c/busses/Kconfig

@@ -291,6 +291,13 @@ config I2C_RPXLITE
 	depends on (RPXLITE || RPXCLASSIC) && I2C
 	select I2C_ALGO8XX
 
+config I2C_S3C2410
+	tristate "S3C2410 I2C Driver"
+	depends on I2C && ARCH_S3C2410
+	help
+	  Say Y here to include support for I2C controller in the
+	  Samsung S3C2410 based System-on-Chip devices.
+
 config I2C_SAVAGE4
 	tristate "S3 Savage 4"
 	depends on I2C && PCI && EXPERIMENTAL

drivers/i2c/busses/Makefile

@@ -26,6 +26,7 @@ obj-$(CONFIG_I2C_PCA_ISA)	+= i2c-pca-isa.o
 obj-$(CONFIG_I2C_PIIX4)		+= i2c-piix4.o
 obj-$(CONFIG_I2C_PROSAVAGE)	+= i2c-prosavage.o
 obj-$(CONFIG_I2C_RPXLITE)	+= i2c-rpx.o
+obj-$(CONFIG_I2C_S3C2410)	+= i2c-s3c2410.o
 obj-$(CONFIG_I2C_SAVAGE4)	+= i2c-savage4.o
 obj-$(CONFIG_I2C_SIS5595)	+= i2c-sis5595.o
 obj-$(CONFIG_I2C_SIS630)	+= i2c-sis630.o

drivers/i2c/busses/i2c-s3c2410.c

+/* linux/drivers/i2c/busses/i2c-s3c2410.c
+ *
+ * Copyright (C) 2004 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/sched.h>
+#include <linux/delay.h>
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/device.h>
+
+#include <asm/hardware.h>
+#include <asm/irq.h>
+
+#include <asm/hardware/clock.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 platfrom_device
+*/
+
+static struct s3c2410_platform_i2c s3c24xx_i2c_default_platform = {
+	.flags		= 0,
+	.slave_addr	= 0x10,
+	.bus_freq	= 100*1000,
+	.max_freq	= 400*1000,
+};
+
+
+/* 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;
+
+	stat = readl(i2c->regs + S3C2410_IICSTAT);
+	stat &= ~S3C2410_IICSTAT_MODEMASK;
+	stat |=  S3C2410_IICSTAT_START;
+	stat |=  S3C2410_IICSTAT_TXRXEN;
+
+	if (msg->flags & I2C_M_RD) {
+		stat |= S3C2410_IICSTAT_MASTER_RX;
+		addr |= 1;
+	} else
+		stat |= S3C2410_IICSTAT_MASTER_TX;
+
+	// todo - check for wether ack wanted or not
+	s3c24xx_i2c_enable_ack(i2c);
+
+	dev_dbg(i2c->dev, "START: %08lx to IICSTAT, %02x to DS\n", stat, addr);
+	writeb(addr, i2c->regs + S3C2410_IICDS);
+	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... */
+
+			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 pt_regs *regs)
+{
+	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
+	}
+
+	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
+ * transfering 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;
+}
+
+/* i2c bus registration info */
+
+static struct i2c_algorithm s3c24xx_i2c_algorithm = {
+	.name			= "S3C2410-I2C-Algorithm",
+	.id			= I2C_ALGO_S3C2410,
+	.master_xfer		= s3c24xx_i2c_xfer,
+};
+
+static struct s3c24xx_i2c s3c24xx_i2c = {
+	.lock	= SPIN_LOCK_UNLOCKED,
+	.wait	= __WAIT_QUEUE_HEAD_INITIALIZER(s3c24xx_i2c.wait),
+	.adap	= {
+		.name			= "s3c2410-i2c",
+		.id			= I2C_ALGO_S3C2410,
+		.algo			= &s3c24xx_i2c_algorithm,
+		.retries		= 2,
+	},
+};
+
+/* 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);
+
+	return 0;
+}
+
+static void s3c24xx_i2c_free(struct s3c24xx_i2c *i2c)
+{
+	if (i2c->clk != NULL && !IS_ERR(i2c->clk)) {
+		clk_disable(i2c->clk);
+		clk_unuse(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 device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct s3c24xx_i2c *i2c = &s3c24xx_i2c;
+	struct resource *res;
+	int ret;
+
+	/* find the clock and enable it */
+
+	i2c->dev = dev;
+	i2c->clk = clk_get(dev, "i2c");
+	if (IS_ERR(i2c->clk)) {
+		dev_err(dev, "cannot get clock\n");
+		ret = -ENOENT;
+		goto out;
+	}
+
+	dev_dbg(dev, "clock source %p\n", i2c->clk);
+
+	clk_use(i2c->clk);
+	clk_enable(i2c->clk);
+
+	/* map the registers */
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (res == NULL) {
+		dev_err(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(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(dev, "cannot map IO\n");
+		ret = -ENXIO;
+		goto out;
+	}
+
+	dev_dbg(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 = 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(dev, "cannot find IRQ\n");
+		ret = -ENOENT;
+		goto out;
+	}
+
+	ret = request_irq(res->start, s3c24xx_i2c_irq, SA_INTERRUPT,
+			  pdev->name, i2c);
+
+	if (ret != 0) {
+		dev_err(dev, "cannot claim IRQ\n");
+		goto out;
+	}
+
+	i2c->irq = res;
+		
+	dev_dbg(dev, "irq resource %p (%ld)\n", res, res->start);
+
+	ret = i2c_add_adapter(&i2c->adap);
+	if (ret < 0) {
+		dev_err(dev, "failed to add bus to i2c core\n");
+		goto out;
+	}
+
+	dev_set_drvdata(dev, i2c);
+
+	dev_info(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 device *dev)
+{
+	struct s3c24xx_i2c *i2c = dev_get_drvdata(dev);
+	
+	if (i2c != NULL) {
+		s3c24xx_i2c_free(i2c);
+		dev_set_drvdata(dev, NULL);
+	}
+
+	return 0;
+}
+
+#ifdef CONFIG_PM
+static int s3c24xx_i2c_resume(struct device *dev, u32 level)
+{
+	struct s3c24xx_i2c *i2c = dev_get_drvdata(dev);
+	
+	if (i2c != NULL && level == RESUME_ENABLE) {
+		dev_dbg(dev, "resume: level %d\n", level);
+		s3c24xx_i2c_init(i2c);
+	}
+
+	return 0;
+}
+
+#else
+#define s3c24xx_i2c_resume NULL
+#endif
+
+/* device driver for platform bus bits */
+
+static struct device_driver s3c24xx_i2c_driver = {
+	.name		= "s3c2410-i2c",
+	.bus		= &platform_bus_type,
+	.probe		= s3c24xx_i2c_probe,
+	.remove		= s3c24xx_i2c_remove,
+	.resume		= s3c24xx_i2c_resume,
+};
+
+static int __init i2c_adap_s3c_init(void)
+{
+	return driver_register(&s3c24xx_i2c_driver);
+}
+
+static void i2c_adap_s3c_exit(void)
+{
+	return driver_unregister(&s3c24xx_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");