Rework the timeout code to use actual time rather than a DELAY() loop and
to use both typical and maximum to allow logging of timeout failures.
Also correct the erase timeout, it is specified in milliseconds not
microseconds like the other timeouts. Do not invoke DELAY() between
status queries as this adds significant latency which in turn reduced
write performance substantially.
Sanity check timeout values from the hardware.
Implement support for buffered writes (only enabled on Intel/Sharp parts
for now). This yields an order of magnitude speedup on the 64MB Intel
StrataFlash parts we use.
When making a copy of the block to modify, also keep a clean copy around
until we are ready to commit the block and use it to avoid unnecessary
erases. In the non-buffer write case, also use it to avoid
unnecessary writes when the block has not been erased. This yields a
significant speedup when doing things like zeroing a block.
Sponsored by: DARPA, AFRL
Reviewed by: imp (previous version)
Intel and Sharp flash power on with their blocks in a "locked" state.
Unlocked them before attempting to perform an erase or write action and
relock when the action is complete.
o add CFI_SUPPORT_STRATAFLASH compile option to enable support
o add new ioctls to get/set the factory and user/oem segments of the PR
and to get/set Protection Lock Register that fuses the user segment
o add #defines for bits in the status register
o update cfi_wait_ready to take an offset so it can be used to wait for
PR write completion and replace constants w/ symbolic names
Note: writing the user segment isn't correct; committing now to get review.
Sponsored by: Carlson Wireless
Reviewed by: imp, Chris Anderson
Memory Interface (CFI). The flash memory can be read and written
to through /dev/cfi# and an ioctl() exists so processes can read
the query information.
The driver supports the AMD and Intel command set, though only
the AMD command has been tested.
Obtained from: Juniper Networks, Inc.
