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lib/boot_device: add RW boot device construct 

The current boot device usage assumes read-only semantics to
the boot device. Any time someone wants to write to the
boot device a device-specific API is invoked such as SPI flash.
Instead, provide a mechanism to retrieve an object that can
be used to perform writes to the boot device. On systems where
the implementations are symmetric these devices can be treated
one-in-the-same. However, for x86 systems with memory mapped SPI
the read-only boot device provides different operations.

BUG=chrome-os-partner:55932

Change-Id: I0af324824f9e1a8e897c2453c36e865b59c4e004
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/16194
Tested-by: build bot (Jenkins)
Reviewed-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
This commit is contained in:
Aaron Durbin 2016-08-10 11:42:42 -05:00 committed by Martin Roth
parent e8e118dd32
commit dcbccd6a1e
2 changed files with 36 additions and 8 deletions
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16
src/include/boot_device.h
View File

@ -18,9 +18,18 @@
#include <commonlib/region.h>
/*
* Please note that the read-only boot device may not be coherent with
* the read-write boot device. Thus, mixing mmap() and writeat() is
* most likely not to work so don't rely on such semantics.
*/
/* Return the region_device for the read-only boot device. */
const struct region_device *boot_device_ro(void);
/* Return the region_device for the read-write boot device. */
const struct region_device *boot_device_rw(void);
/*
* Create a sub-region of the read-only boot device.
* Returns 0 on success, < 0 on error.
@ -28,6 +37,13 @@ const struct region_device *boot_device_ro(void);
int boot_device_ro_subregion(const struct region *sub,
struct region_device *subrd);
/*
* Create a sub-region of the read-write boot device.
* Returns 0 on success, < 0 on error.
*/
int boot_device_rw_subregion(const struct region *sub,
struct region_device *subrd);
/*
* Initialize the boot device. This may be called multiple times within
* a stage so boot device implementations should account for this behavior.

28
src/lib/boot_device.c
View File

@ -20,18 +20,30 @@ void __attribute__((weak)) boot_device_init(void)
/* Provide weak do-nothing init. */
}
static int boot_device_subregion(const struct region *sub,
struct region_device *subrd,
const struct region_device *parent)
{
if (parent == NULL)
return -1;
return rdev_chain(subrd, parent, region_offset(sub), region_sz(sub));
}
int boot_device_ro_subregion(const struct region *sub,
struct region_device *subrd)
{
const struct region_device *boot_dev;
/* Ensure boot device has been initialized at least once. */
boot_device_init();
boot_dev = boot_device_ro();
if (boot_dev == NULL)
return -1;
return rdev_chain(subrd, boot_dev, region_offset(sub), region_sz(sub));
return boot_device_subregion(sub, subrd, boot_device_ro());
}
int boot_device_rw_subregion(const struct region *sub,
struct region_device *subrd)
{
/* Ensure boot device has been initialized at least once. */
boot_device_init();
return boot_device_subregion(sub, subrd, boot_device_rw());
}