[PATCH] I2C: EXYNOS: Add slave support to i2c
Giridhar Maruthy
giridhar.maruthy at linaro.org
Mon Dec 3 07:16:22 EST 2012
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 <giridhar.maruthy at linaro.org>
---
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
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