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authorBen Dooks <ben-linux@fluff.org>2007-05-01 23:26:35 +0200
committerJean Delvare <khali@hyperion.delvare>2007-05-01 23:26:35 +0200
commite00a8cdf325346c531c841ee85c803792db60157 (patch)
treecd77aa2a2f94e8577f73ec3e2e4073ad94c184b9 /drivers/i2c
parente8c76eed2ecdb8e9ca5339761d2c076d32b7cbca (diff)
i2c-s3c2410: Fix I2C SDA to SCL setup time
Fix the setup time for SDA to SCL due to the way the S3C24XX I2C controller works. Signed-off-by: Ben Dooks <ben-linux@fluff.org> Signed-off-by: Jean Delvare <khali@linux-fr.org>
Diffstat (limited to 'drivers/i2c')
-rw-r--r--drivers/i2c/busses/i2c-s3c2410.c26
1 files changed, 20 insertions, 6 deletions
diff --git a/drivers/i2c/busses/i2c-s3c2410.c b/drivers/i2c/busses/i2c-s3c2410.c
index 3eb5958f347..e8395be0d92 100644
--- a/drivers/i2c/busses/i2c-s3c2410.c
+++ b/drivers/i2c/busses/i2c-s3c2410.c
@@ -61,6 +61,8 @@ struct s3c24xx_i2c {
unsigned int msg_idx;
unsigned int msg_ptr;
+ unsigned int tx_setup;
+
enum s3c24xx_i2c_state state;
void __iomem *regs;
@@ -199,8 +201,11 @@ static void s3c24xx_i2c_message_start(struct s3c24xx_i2c *i2c,
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);
+ /* 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);
@@ -322,7 +327,15 @@ static int i2s_s3c_irq_nextbyte(struct s3c24xx_i2c *i2c, unsigned long iicstat)
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 */
@@ -570,9 +583,10 @@ static const struct i2c_algorithm s3c24xx_i2c_algorithm = {
};
static struct s3c24xx_i2c s3c24xx_i2c = {
- .lock = __SPIN_LOCK_UNLOCKED(s3c24xx_i2c.lock),
- .wait = __WAIT_QUEUE_HEAD_INITIALIZER(s3c24xx_i2c.wait),
- .adap = {
+ .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,