drm/radeon/kms: add support for gui idle interrupts (v4)

Useful for certain power management operations.  You
need to wait for the GUI engine (2D, 3D, CP, etc.) to be
idle before changing clocks or adjusting engine parameters.

(v2) Fix gui idle enable on pre-r6xx asics

(v3) The gui idle interrrupt status bit is permanently asserted
on pre-r6xx chips, but the interrrupt is still generated.
workaround it in the driver.

(v4) Add support for evergreen

Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/radeon_pm.c b/drivers/gpu/drm/radeon/radeon_pm.c
index a4b5749..6dfeb9c 100644
--- a/drivers/gpu/drm/radeon/radeon_pm.c
+++ b/drivers/gpu/drm/radeon/radeon_pm.c
@@ -27,6 +27,7 @@
 #define RADEON_IDLE_LOOP_MS 100
 #define RADEON_RECLOCK_DELAY_MS 200
 #define RADEON_WAIT_VBLANK_TIMEOUT 200
+#define RADEON_WAIT_IDLE_TIMEOUT 200
 
 static bool radeon_pm_debug_check_in_vbl(struct radeon_device *rdev, bool finish);
 static void radeon_pm_set_clocks_locked(struct radeon_device *rdev);