Hi all,I have some probably dumb questions regarding the definition of i2c slaves in the of device tree file...
My test system is a lite5200b board to which I attached two pca8575 io expander chips at i2c addresses 0x20 and 0x21. Using the stock kernel 2.6.29, I added the driver from the GPIO section, but I couldn't figure out how to add them to the dts file. I tried e.g.
<snip>
i...@3d40 {
[...]
compatible = "fsl,mpc5200b-i2c","fsl,mpc5200-i2c","fsl-i2c";
[...]
g...@20 {
compatible = "pcf857x";
device_type = "gpio";
reg = <0x20 1>;
};
};
</snip>
and some other like "gpio-controller" instead of "gpio" but (surprise)
it doesn't work - dmesg says that the driver is registered, but nothing
else shows up. Unfortunately, I couldn't find documentation about the
naming conventions of the i2c child nodes.
As I actually want to use the chips as parallel io (not separate gpio's) and thus would need to write my own driver I wonder if I really have to declare it in the device tree? Would the simple way -just load the kernel module as with arm/intel- also work? Would it be possible to use additional resources like an interrupt pin on the '5200 without the device tree?
Any information about a proper approach would be really helpful! Thanks in advance, Albrecht.
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