I2C: S3C2410: Add MODULE_ALIAS() for s3c2440 device.

[linux-2.6/kmemtrace.git] / drivers / i2c / busses / i2c-s3c2410.c

/* 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/plat-s3c/regs-iic.h>
#include <asm/plat-s3c/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;

        unsigned int            tx_setup;

        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 here to ensure the data byte has gotten onto the bus
         * before the transaction is started */

        ndelay(i2c->tx_setup);

        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", __func__);
                goto out;
                break;

        case STATE_STOP:
                dev_err(i2c->dev, "%s: called in STATE_STOP\n", __func__);
                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, -ENXIO);
                        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
                 * as this is 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
                 */

                if (!(i2c->msg->flags & I2C_M_IGNORE_NAK)) {
                        if (iicstat & S3C2410_IICSTAT_LASTBIT) {
                                dev_dbg(i2c->dev, "WRITE: No Ack\n");

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

        retry_write:

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

                        /* delay after writing the byte to allow the
                         * data setup time on the bus, as writing the
                         * data to the register causes the first bit
                         * to appear on SDA, and SCL will change as
                         * soon as the interrupt is acknowledged */

                        ndelay(i2c->tx_setup);

                } 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
                 */

                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(s3c24xx_i2c.lock),
        .wait           = __WAIT_QUEUE_HEAD_INITIALIZER(s3c24xx_i2c.wait),
        .tx_setup       = 50,
        .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;
}

/* 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 err_noclk;
        }

        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 err_clk;
        }

        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 err_clk;
        }

        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 err_ioarea;
        }

        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 err_iomap;

        /* 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 err_iomap;
        }

        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 err_iomap;
        }

        i2c->irq = res;
                
        dev_dbg(&pdev->dev, "irq resource %p (%lu)\n", res,
                (unsigned long)res->start);

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

        platform_set_drvdata(pdev, i2c);

        dev_info(&pdev->dev, "%s: S3C I2C adapter\n", i2c->adap.dev.bus_id);
        return 0;

 err_irq:
        free_irq(i2c->irq->start, i2c);

 err_iomap:
        iounmap(i2c->regs);

 err_ioarea:
        release_resource(i2c->ioarea);
        kfree(i2c->ioarea);

 err_clk:
        clk_disable(i2c->clk);
        clk_put(i2c->clk);

 err_noclk:
        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);

        i2c_del_adapter(&i2c->adap);
        free_irq(i2c->irq->start, i2c);

        clk_disable(i2c->clk);
        clk_put(i2c->clk);

        iounmap(i2c->regs);

        release_resource(i2c->ioarea);
        kfree(i2c->ioarea);

        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");
MODULE_ALIAS("platform:s3c2410-i2c");
MODULE_ALIAS("platform:s3c2440-i2c");