[U-Boot-Users] SOFT_I2C on at91rm9200

[Nils Gjerdevik]

Hi,
I'm trying to store the u-boot environment in an EEPROM (at24c128) on
a custom at91rm9200 based board. This fails when using the included
HARD_I2C driver, and since there are known problems with the I2C
controller on this uC, I'm trying to set up SOFT_I2C instead, without
success so far...
This is what I've put in my config file:

#define I2C_INIT \
do { \
  *AT91C_PIOA_PER = AT91C_PA25_TWD | AT91C_PA26_TWCK; \
  *AT91C_PIOA_ODR = AT91C_PA25_TWD; \
  *AT91C_PIOA_OER = AT91C_PA26_TWCK; \
}while(0)

#define I2C_ACTIVE (*AT91C_PIOA_OER = AT91C_PA25_TWD)

#define I2C_TRISTATE (*AT91C_PIOA_ODR = AT91C_PA25_TWD)

#define I2C_READ ((*AT91C_PIOA_PDSR & AT91C_PA25_TWD) != 0)

#define I2C_SDA(bit) \
if(bit) { \
  *AT91C_PIOA_SODR = AT91C_PA25_TWD; \
} else { \
  *AT91C_PIOA_CODR = AT91C_PA25_TWD; \
}

#define I2C_SCL(bit) \
if(bit) { \
  *AT91C_PIOA_SODR = AT91C_PA26_TWCK; \
} else { \
  *AT91C_PIOA_CODR = AT91C_PA26_TWCK; \
}

#define I2C_DELAY    udelay(5)

Can anyone see what's wrong with this code?
I can access the EEPROM without problems in Linux, using the
bit-banging driver, so the board design should be OK. The code above
is(loosely) based on the Linux bit-banging driver.

Regards,
Nils