i2c_read_reg on phytec-som-am335x returns wrong data from EEPROM

[Martin Hollingsworth <Martin.Hollingsworth@itk-engineering.de>]

Hello folks,
I am having trouble reading from the 4k EEPROM via I2C on the phytec-som-am335x board. What I want to achieve is, that the code in board.c reads a value from EEPROM, evaluates it and then adds the value as globalvar to the userland for scripting. However if I read the data using the function from below, the i2c_read_reg() returns with SUCCESS but the data read to the buffer is incorrect. I use the following snippet of code to read the data within the physom_devices_init() function within the board.c file.

------------
struct i2c_adapter *adapter = i2c_get_adapter(0);
if(adapter)
{
    struct i2c_client client;
    client.adapter = adapter;
    client.addr = 0x52;
	char buff[32] = {0xFF};
    if(i2c_read_reg(&client, 0xFE0, buff, sizeof(buff)) > 0)
    {
		for( ii = 0; ii < 32; ii++ )
		{
			printf( "%02X", buff[ii] );
		}
	[...]
------------

If I compare the EEPROM access in barebox userland, I see similar problems. All access to the EEPROM via I2C commands only work correct, if I set the "-w" (use 16bit word access) flag. In all cases the i2c_read or i2c_write functions return 0 (success) but the read or write was not executed correctly. See the example, where both reads should return the same data:

------------
barebox@Phytec phyCORE AM335x:/ i2c_read -b 0 -a 0x52 -r 0xFE0 -c 32 -w 
0xaa 0xff 0xaa 0xff [...] --> OK, DATA is correct
barebox@Phytec phyCORE AM335x:/ i2c_read -b 0 -a 0x52 -r 0xFE0 -c 32
0xf3 0xfd 0x54 0x23 [...] --> RETURNVALUE = 0 (SUCCESS), BUT READ DATA IS WRONG
------------

However if I access the EEPROM using the device definition /dev/eeprom0, as provided by the DTSI file, the usual memory commands in userland - like memset, mw and md - all work just fine.

What am I overlooking here? How do I configure i2c_read_reg() in C-Code to do WORD access to the EEPROM?

Any suggestion would be appreciated.
Regards, Martin

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