[ECOS] Question about writing IO mapped device driver?

[HuangQiang]

Hi all:
   I am using ARM E7T, I would like to have some external IO mapped device
like: LCD, Keypad, CAN controller...  Is it resonable (worthy of doing so)
to write the device driver for such ext devices? I can control the ext
device via the memory access directly, but I would like to do it in a more
standard way. so I plan to make the device driver. I also knew that quite a
lot deivce driver in eCOS use two layer design, one for logical layer and
one for the physical layer (hardware). I wondered that is there any
available general logical layer device driver for such mapped IO devices? So
I can concentrate on the (hardware ) physical layer device driver. Or any
standard way for the writing the logical layer for the memory mapped IO
devices?

Thanks for your help!

james