Ayman El-Khashab wrote:

Ok, here is what I used.  I see the nodes created in /sys/bus/i2c/... 
but I see four of them at address 0x50,0x51,0x52,0x53.  That surprised
me since I only have 3 of them in the device tree.  However, in any case
I did not see a way to read or write them.  In one case I was able to
cat the file "eeprom", but it was only 256 bytes and did not exist for
the other 3 devices.  Here is the section of my device tree ... I do 
see the controller being initialized in dmesg, it is just the read and
write that is eluding me.

One question I did have was within another sample device tree, there was
a comment that "this makes address 0x50 and 0x51"?  Does that mean that
large eeproms are spread over several nodes?  I searched around but
could
not find an example of how to use this at24 to access my E2 from
userspace.

Thanks
Ayman


                        IIC0: i2c@ef600700 {
                                compatible = "ibm,iic-460ex", "ibm,iic";
                                reg = <0xef600700 0x00000014>;
                                interrupt-parent = <&UIC0>;
                                interrupts = <0x2 0x4>;
                                #address-cells = <1>;
                                #size-cells = <0>;

                                at24@50 {
                                        compatible = "at24,at24c128";
                                        reg = <0x50>;
                                };
                                at24@52 {
                                        compatible = "at24,at24c128";
                                        reg = <0x52>;
                                };
                                at24@53 {
                                        compatible = "at24,at24c128";
                                        reg = <0x53>;
                                };
				}


  

If you're using Denx kernel, you should add your  at24 device to 
i2c_devices[]
in drivers/i2c/busses/i2c-ibm_of.c This will pass your device tree data 
to at24 driver.

Felix.