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

[David Hendricks]

Second try, with the patch actually attached this time.

Signed-off-by: David Hendricks <dhendrix at google.com>

On Thu, Apr 21, 2011 at 9:28 PM, David Hendricks <dhendrix at google.com>wrote:

> Hi everyone,
> Lately we've been looking into reverse PCI<http://flashrom.org/trac/flashrom/changeset/1232>and
> MMIO <http://patchwork.coreboot.org/patch/2331/> writes, along with the
> shutdown callback mechanism.
>
> The main usage case for Flashrom makes this a pretty simple matter, since
> most users only worry about a single programmer being used. However, when
> external devices are used which depend on internal programmer settings,
> things can get messy.
>
> Consider the case of a laptop with an x86 southbridge and an EC -- To
> communicate with the EC thru the LPC/FWH interface, some register settings
> in the southbridge might need to be changed. The code flow should be:
> 1. Set up SB, use rpci_* and rmmio_* to register reverse PCI and MMIO
> callbacks wherever necessary.
> 2. Set up EC.
> 3. Run code.
> 4. Call EC shutdown routine.
> 5. Reverse SB PCI/MMIO writes.
>
> However, the current code calls the programmer shutdown routine in step 4
> *after* doing all shutdown callbacks in step 5. This causes southbridge
> registers to be reverted before the EC's shutdown routine is called,
> potentially making the EC unreachable.
>
> The attached patch addresses this by using programmer shutdown functions
> the same as any other shutdown callback. The internal_shutdown function is
> registered early in the internal_init() function so that newly discovered
> external programmers (ie SuperIO/EC LPC -> SPI bridges) can be discovered
> and have their shutdown callbacks added in the correct order.
>
> If this seems useful, we should make necessary changes to other programmers
> as well before committing this patch.
>
> Signed-off-by: David Hendricks <dhendrix at google.com>
>
> --
> David Hendricks (dhendrix)
> Systems Software Engineer, Google Inc.
>



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