mpc83xx: Fix empty i2c reads/writes in fsl_i2c.c
Fix empty i2c reads/writes, i2c_write(0x50, 0x00, 0, NULL, 0)
which is used to se if an slave will ACK after receiving its address.
Correct i2c probing to use this method as the old method could upset
a slave as it wrote a data byte to it.
Add a small delay in i2c_init() to let the controller
shutdown any ongoing I2C activity.
Signed-off-by: Joakim Tjernlund <Joakim.Tjernlund@transmode.se>
diff --git a/drivers/fsl_i2c.c b/drivers/fsl_i2c.c
index c929096..ebae5af 100644
--- a/drivers/fsl_i2c.c
+++ b/drivers/fsl_i2c.c
@@ -58,6 +58,7 @@
dev = (struct fsl_i2c *) (CFG_IMMR + CFG_I2C_OFFSET);
writeb(0, &dev->cr); /* stop I2C controller */
+ udelay(5); /* let it shutdown in peace */
writeb(0x3F, &dev->fdr); /* set bus speed */
writeb(0x3F, &dev->dfsrr); /* set default filter */
writeb(slaveadd << 1, &dev->adr); /* write slave address */
@@ -191,15 +192,17 @@
int
i2c_read(u8 dev, uint addr, int alen, u8 *data, int length)
{
- int i = 0;
+ int i = -1; /* signal error */
u8 *a = (u8*)&addr;
if (i2c_wait4bus() >= 0
&& i2c_write_addr(dev, I2C_WRITE_BIT, 0) != 0
- && __i2c_write(&a[4 - alen], alen) == alen
- && i2c_write_addr(dev, I2C_READ_BIT, 1) != 0) {
+ && __i2c_write(&a[4 - alen], alen) == alen)
+ i = 0; /* No error so far */
+
+ if (length
+ && i2c_write_addr(dev, I2C_READ_BIT, 1) != 0)
i = __i2c_read(data, length);
- }
writeb(I2C_CR_MEN, &i2c_dev[i2c_bus_num]->cr);
@@ -212,7 +215,7 @@
int
i2c_write(u8 dev, uint addr, int alen, u8 *data, int length)
{
- int i = 0;
+ int i = -1; /* signal error */
u8 *a = (u8*)&addr;
if (i2c_wait4bus() >= 0
@@ -232,16 +235,14 @@
int
i2c_probe(uchar chip)
{
- int tmp;
-
- /*
- * Try to read the first location of the chip. The underlying
- * driver doesn't appear to support sending just the chip address
- * and looking for an <ACK> back.
+ /* For unknow reason the controller will ACK when
+ * probing for a slave with the same address, so skip
+ * it.
*/
- udelay(10000);
+ if (chip == (readb(&i2c_dev[i2c_bus_num]->adr) >> 1))
+ return -1;
- return i2c_read(chip, 0, 1, (uchar *)&tmp, 1);
+ return i2c_read(chip, 0, 0, NULL, 0);
}
uchar