> Looking at the device tree for this board, it appears U-Boot remaps the > IMMR registers to 0xe0000000. They are no longer accessible at > 0xff400000. > > I would recommend studying arch/powerpc/boot/dts/mpc8377_rdb.dts in the > Linux source code. That describes the device layout on your board after > U-Boot has run. > > A wonderful tool for testing devices from userspace is "busybox devmem". > It allows you to poke any physical address with any value. The output of > "busybox devmem --help" should get you started. As a quick example, > "busybox devmem 0xe0000c00 w 0x1" will write the 32-bit value 0x1 to > address 0xe0000c00. > > I would also recommend using the built-in Linux GPIO API. It works, you > just need to figure out how to use it. It will be much easier to get > your code upstream if you use the provided APIs. > > The Documentation/gpio.txt file should help you in understanding the > in-kernel Linux GPIO API. I'm afraid I don't have much experience other > than accessing it via sysfs from userspace. > > Ira >
Hi Ira, Thanks for another great reply. Now I can also access gpio memory map registers. Thanks and Regards, Ravi Gupta
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