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baytrail: Switch from ACPI mode to PCI mode for legacy support

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Most Baytrail based devices MMIO registers are reported in ACPI
space and the device's PCI config space is disabled. The PCI config
space is required for many "legacy" OSs that don't have the ACPI
driver loading mechanism. Depthcharge signals the legacy boot
path via the SMI 0xCC and the coreboot SMI handler can switch the
device specific registers to re-enable PCI config space.

BUG=chrome-os-partner:30836
BRANCH=None
TEST=Build and boot Rambi SeaBIOS.

Change-Id: Ia5e54f4330eda10a01ce3de5aa4d86779d6e1bf9
Signed-off-by: Marc Jones <marc.jones@se-eng.com>
Reviewed-on: https://chromium-review.googlesource.com/219801
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Mike Loptien <mike.loptien@se-eng.com>
Tested-by: Mike Loptien <mike.loptien@se-eng.com>
This commit is contained in:
Marc Jones 2014-09-24 10:53:48 -06:00 • committed by chrome-internal-fetch
commit dbb9205ee2
3 changed files with 61 additions and 0 deletions
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1
src/include/cpu/x86/smm.h
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@ -459,6 +459,7 @@ typedef struct {
#define APM_CNT_MBI_UPDATE 0xeb
#define APM_CNT_GNVS_UPDATE 0xea
#define APM_CNT_FINALIZE 0xcb
#define APM_CNT_LEGACY 0xcc
#define APM_STS 0xb3
/* SMI handler function prototypes */