ACPI: Add support for exposing BGRT data

ACPI 5.0 adds the BGRT, a table that contains a pointer to the firmware
boot splash and associated metadata. This simple driver exposes it via
/sys/firmware/acpi in order to allow bootsplash applications to draw their
splash around the firmware image and reduce the number of jarring graphical
transitions during boot.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-firmware-acpi b/Documentation/ABI/testing/sysfs-firmware-acpi
index 4f9ba3c2fca7..dd930c8db41f 100644
--- a/Documentation/ABI/testing/sysfs-firmware-acpi
+++ b/Documentation/ABI/testing/sysfs-firmware-acpi
@@ -1,3 +1,23 @@
+What:           /sys/firmware/acpi/bgrt/
+Date:           January 2012
+Contact:        Matthew Garrett <mjg@redhat.com>
+Description:
+                The BGRT is an ACPI 5.0 feature that allows the OS
+                to obtain a copy of the firmware boot splash and
+                some associated metadata. This is intended to be used
+                by boot splash applications in order to interact with
+                the firmware boot splash in order to avoid jarring
+                transitions.
+
+                image: The image bitmap. Currently a 32-bit BMP.
+                status: 1 if the image is valid, 0 if firmware invalidated it.
+                type: 0 indicates image is in BMP format.
+                version: The version of the BGRT. Currently 1.
+                xoffset: The number of pixels between the left of the screen
+                         and the left edge of the image.
+                yoffset: The number of pixels between the top of the screen
+                         and the top edge of the image.
+
 What:           /sys/firmware/acpi/interrupts/
 Date:           February 2008
 Contact:        Len Brown <lenb@kernel.org>