cfi_cmdset_0002: reading and writing one time programmable memory

Hello,

I would like to extend the AMD command set for reading/writing/locking of one time programmable (OTP) memory areas (called secure silicon in Spansion device, called extended memory region in Micron devices...). In particular I would like to support the 256 byte extended memory region of Micron M29EW devices. Currently the code in drivers/mtd/chips/cfi_cmdset_0002.c only supports reading of the first 8 bytes of this memory area.

I have already implemented this support partially, but before posting a first patchset, I have a few questions regarding the current code in do_read_secsi_onechip() in drivers/mtd/chips/cfi_cmdset_0002.c.

This function first waits for the chip to get into FL_READY state? Could the get_chip() function be used instead here?

After sending the 0xaa/0x55/0x88 command to the device, the OTP/SecSi/... memory is mapped to addresses 0x00 - 0xff of the device. Does this require putting xip_disable/xip_enable around this code? Should the cache get invalidated before reading? Should the function get marked __xipram?

Thanks for your help!
Christian