drm/radeon: implement handler for ACPI event

Set up an handler for ACPI events and respond to brightness change
requests from the system BIOS.
v2: fix notification when using device-specific command codes
(tested by Pali Rohár <pali.rohar@gmail.com>); cache the encoder
controlling the backlight during the initialization to avoid searching
it every time (suggested by Alex Deucher).
v3: whitespace fixes (Alex Deucher).

Signed-off-by: Luca Tettamanti <kronos.it@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/gpu/drm/radeon/radeon_acpi.h b/drivers/gpu/drm/radeon/radeon_acpi.h
index 642aa4719454..be4af76f213d 100644
--- a/drivers/gpu/drm/radeon/radeon_acpi.h
+++ b/drivers/gpu/drm/radeon/radeon_acpi.h
@@ -24,6 +24,12 @@
 #ifndef RADEON_ACPI_H
 #define RADEON_ACPI_H
 
+struct radeon_device;
+struct acpi_bus_event;
+
+int radeon_atif_handler(struct radeon_device *rdev,
+                struct acpi_bus_event *event);
+
 /* AMD hw uses four ACPI control methods:
  * 1. ATIF
  * ARG0: (ACPI_INTEGER) function code