This patch adds slave support to i2c. The dt entry i2c-mode
decides at probe time if the controller needs to work in
slave mode and the controller is accordingly programmed.

Signed-off-by: Giridhar Maruthy <redacted>
---
 drivers/i2c/busses/i2c-s3c2410.c |  100
++++++++++++++++++++++++++------------
 1 file changed, 68 insertions(+), 32 deletions(-)

diff --git a/drivers/i2c/busses/i2c-s3c2410.c

b/drivers/i2c/busses/i2c-s3c2410.c
index e93e7d6..d83a6d7 100644

--- a/drivers/i2c/busses/i2c-s3c2410.c
+++ b/drivers/i2c/busses/i2c-s3c2410.c

@@ -53,6 +53,9 @@
 /* Max time to wait for bus to become idle after a xfer (in us) */
 #define S3C2410_IDLE_TIMEOUT   5000

+/* To find the master/slave mode of current controller */
+#define is_master(i2c) (!i2c->i2c_mode)
+
 /* i2c controller state */
 enum s3c24xx_i2c_state {
        STATE_IDLE,

@@ -89,6 +92,8 @@ struct s3c24xx_i2c {
 #ifdef CONFIG_CPU_FREQ
        struct notifier_block   freq_transition;
 #endif
+       /* i2c_mode: 0 is for master; and 1 is for slave */
+       unsigned int            i2c_mode;
 };

 static struct platform_device_id s3c24xx_driver_ids[] = {

@@ -202,11 +207,21 @@ static void s3c24xx_i2c_message_start(struct

s3c24xx_i2c *i2c,
        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 (is_master(i2c)) {
+               /* Master mode */
+               if (msg->flags & I2C_M_RD) {
+                       stat |= S3C2410_IICSTAT_MASTER_RX;
+                       addr |= 1;
+               } else
+                       stat |= S3C2410_IICSTAT_MASTER_TX;
+       } else {
+               /* Slave mode */
+               if (msg->flags & I2C_M_RD) {
+                       stat |= S3C2410_IICSTAT_SLAVE_RX;
+                       addr |= 1;
+               } else
+                       stat |= S3C2410_IICSTAT_SLAVE_TX;
+       }

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

@@ -228,8 +243,10 @@ static void s3c24xx_i2c_message_start(struct

s3c24xx_i2c *i2c,
        dev_dbg(i2c->dev, "iiccon, %08lx\n", iiccon);
        writel(iiccon, i2c->regs + S3C2410_IICCON);

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

 static inline void s3c24xx_i2c_stop(struct s3c24xx_i2c *i2c, int ret)

@@ -272,14 +289,19 @@ static inline void s3c24xx_i2c_stop(struct

s3c24xx_i2c *i2c, int ret)
         * devices, the host as Master and the HDMIPHY device as the slave.
         * Skipping the STOP condition has been tested on this bus and
works.
         */
-       if (i2c->quirks & QUIRK_HDMIPHY) {
-               /* Stop driving the I2C pins */
-               iicstat &= ~S3C2410_IICSTAT_TXRXEN;
-       } else {
-               /* stop the transfer */
-               iicstat &= ~S3C2410_IICSTAT_START;
+       if (is_master(i2c)) {
+               if (i2c->quirks & QUIRK_HDMIPHY) {
+                       /* Stop driving the I2C pins */
+                       iicstat &= ~S3C2410_IICSTAT_TXRXEN;
+               } else {
+                       /* stop the transfer */
+                       if (is_master(i2c)) {
+                               /* Start/Stop required only for master */
+                               iicstat &= ~S3C2410_IICSTAT_START;
+                       }
+               }
+               writel(iicstat, i2c->regs + S3C2410_IICSTAT);
        }
-       writel(iicstat, i2c->regs + S3C2410_IICSTAT);

        i2c->state = STATE_STOP;

@@ -348,7 +370,8 @@ static int i2c_s3c_irq_nextbyte(struct s3c24xx_i2c

*i2c, unsigned long iicstat)
                 */

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

                        dev_dbg(i2c->dev, "ack was not received\n");

@@ -380,7 +403,7 @@ static int i2c_s3c_irq_nextbyte(struct s3c24xx_i2c

*i2c, unsigned long iicstat)
                 * end of the message, and if so, work out what to do
                 */

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

@@ -432,7 +455,6 @@ static int i2c_s3c_irq_nextbyte(struct s3c24xx_i2c

*i2c, unsigned long iicstat)

                } else {
                        /* send stop */
-
                        s3c24xx_i2c_stop(i2c, 0);
                }
                break;

@@ -447,7 +469,7 @@ static int i2c_s3c_irq_nextbyte(struct s3c24xx_i2c

*i2c, unsigned long iicstat)
                i2c->msg->buf[i2c->msg_ptr++] = byte;

  prepare_read:
-               if (is_msglast(i2c)) {
+               if (is_msglast(i2c) && is_master(i2c)) {
                        /* last byte of buffer */

                        if (is_lastmsg(i2c))

@@ -612,11 +634,13 @@ static int s3c24xx_i2c_doxfer(struct s3c24xx_i2c *i2c,
        if (i2c->suspended)
                return -EIO;

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

ret);
+                       ret = -EAGAIN;
+                       goto out;
+               }
        }

        i2c->msg     = msgs;

@@ -628,23 +652,29 @@ static int s3c24xx_i2c_doxfer(struct s3c24xx_i2c *i2c,
        s3c24xx_i2c_enable_irq(i2c);
        s3c24xx_i2c_message_start(i2c, msgs);

-       timeout = wait_event_timeout(i2c->wait, i2c->msg_num == 0, HZ * 5);
+       if (is_master(i2c))
+               timeout = wait_event_timeout(i2c->wait,\
+                               i2c->msg_num == 0, HZ * 5);
+       else
+               wait_event_interruptible(i2c->wait, i2c->msg_num == 0);

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

-       /* For QUIRK_HDMIPHY, bus is already disabled */
-       if (i2c->quirks & QUIRK_HDMIPHY)
-               goto out;
+               /* For QUIRK_HDMIPHY, bus is already disabled */
+               if (i2c->quirks & QUIRK_HDMIPHY)
+                       goto out;

-       s3c24xx_i2c_wait_idle(i2c);
+               s3c24xx_i2c_wait_idle(i2c);
+       }

  out:
        return ret;

@@ -963,6 +993,7 @@ s3c24xx_i2c_parse_dt(struct device_node *np, struct

s3c24xx_i2c *i2c)
        of_property_read_u32(np, "samsung,i2c-slave-addr",
&pdata->slave_addr);
        of_property_read_u32(np, "samsung,i2c-max-bus-freq",
                                (u32 *)&pdata->frequency);
+       of_property_read_u32(np, "samsung,i2c-mode", &i2c->i2c_mode);
 }
 #else
 static void

@@ -1004,6 +1035,10 @@ static int s3c24xx_i2c_probe(struct platform_device

*pdev)
                goto err_noclk;
        }

+       /* By default, i2c works in master mode */
+       /* This currently will be updated using DT */
+       i2c->i2c_mode   = 0;
+
        i2c->quirks = s3c24xx_get_device_quirks(pdev);
        if (pdata)
                memcpy(i2c->pdata, pdata, sizeof(*pdata));

@@ -1017,6 +1052,7 @@ static int s3c24xx_i2c_probe(struct platform_device

*pdev)
        i2c->adap.class   = I2C_CLASS_HWMON | I2C_CLASS_SPD;
        i2c->tx_setup     = 50;

+
        init_waitqueue_head(&i2c->wait);

        /* find the clock and enable it */
--
1.7.9.5
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.infradead.org/pipermail/linux-arm-kernel/attachments/20121203/a4a4ec03/attachment-0001.html>