[U-Boot] [PATCH 1/3] fsl_i2c: Wait for STOP condition to propagate

Joakim Tjernlund
2009-09-17T09:07:15Z

After issuing a STOP one must wait until the STOP has completed
on the bus before doing something new to the controller.

Also add an extra read of SR as the manual mentions doing that
is a good idea.

Remove surplus write of CR just before a write, isn't required and
could potentially disturb the I2C bus.

Signed-off-by: Joakim Tjernlund <Joakim.Tjernlund@transmode.se>
---
drivers/i2c/fsl_i2c.c | 12 ++++++++----
1 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/i2c/fsl_i2c.c b/drivers/i2c/fsl_i2c.c
index 47bbf79..56f9680 100644
--- a/drivers/i2c/fsl_i2c.c
+++ b/drivers/i2c/fsl_i2c.c
@@ -223,7 +223,7 @@ i2c_init(int speed, int slaveadd)
#endif
}

-static __inline__ int
+static int
i2c_wait4bus(void)
{
unsigned long long timeval = get_ticks();
@@ -248,6 +248,8 @@ i2c_wait(int write)
csr = readb(&i2c_dev[i2c_bus_num]->sr);
if (!(csr & I2C_SR_MIF))
continue;
+ /* Read again to allow register to stabilise */
+ csr = readb(&i2c_dev[i2c_bus_num]->sr);

writeb(0x0, &i2c_dev[i2c_bus_num]->sr);

@@ -293,9 +295,6 @@ __i2c_write(u8 *data, int length)
{
int i;

- writeb(I2C_CR_MEN | I2C_CR_MSTA | I2C_CR_MTX,
- &i2c_dev[i2c_bus_num]->cr);
-
for (i = 0; i < length; i++) {
writeb(data[i], &i2c_dev[i2c_bus_num]->dr);

@@ -351,6 +350,9 @@ i2c_read(u8 dev, uint addr, int alen, u8 *data, int length)
&& i2c_write_addr(dev, I2C_READ_BIT, 1) != 0)
i = __i2c_read(data, length);

+ if (length && i2c_wait4bus()) /* Wait until STOP */
+ debug("i2c_read: wait4bus timed out\n");
+
writeb(I2C_CR_MEN, &i2c_dev[i2c_bus_num]->cr);

if (i == length)
@@ -372,6 +374,8 @@ i2c_write(u8 dev, uint addr, int alen, u8 *data, int length)
}

writeb(I2C_CR_MEN, &i2c_dev[i2c_bus_num]->cr);
+ if (i2c_wait4bus()) /* Wait until STOP */
+ debug("i2c_write: wait4bus timed out\n");

if (i == length)
return 0;
--
1.6.4.3