[flashrom] [Patch] + RFC: Use shutdown callback mechanism to shutdown programmers

[David Hendricks]

Finally got a chance to revise this. There are a lot of small, tedious
changes to all the programmer .c files and some interesting changes to
flashrom.c. Otherwise it's a pretty simple patch.

To recap from earlier discussion, this version does the following:
- Registers a shutdown callback during initialization for each programmer.
See notes below.
- Kills the .shutdown function pointer from programmer_entry struct
- Updates all programmer shutdown functions to return an int and take a void
*data arg. Also, make them static.
- programmer_shutdown() checks the return code of all shutdown callbacks.

A few minor questions:
- If programmer_init() fails when called in cli_classic(), should we call
programmer_shutdown()? As Carl-Daniel noted earlier, this could potentially
be used to do stuff like release_io_perms(), or perhaps free resources
allocated by an init routine that fails.
- nicintel_spi -- Looks like flash write enable/disable should be done using
rpci?
- drkaiser - shutdown function missing a physunmap?

Additional notes:
- Most programmers have a simple init routines with no failure condition, so
placement of register_shutdown() doesn't really matter.
- serialport_shutdown non-static since it's used by buspirate.
- There were cases where the programmer's init routine would do something
less simple, like open a file or map physical memory, and the shutdown
callback would undo it. In those cases, placement took a little more
thought. Someone more familiar with those should double-check that this
patch does the right thing for buspirate, serprog, and satamv.

I did a quick test using an NM10/ICH7 platform and callbacks were shown in
verbose mode output as expected.
Signed-off-by: David Hendricks <dhendrix at google.com>

-- 
David Hendricks (dhendrix)
Systems Software Engineer, Google Inc.
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