drm/vc4: Add CTM support

The hardware has a single block for applying a CTM prior to gamma lut.
It can be fed with pixels from one of our CRTC at a time and uses a
matrix with S0.9 scalars. Use private atomic state to reject attempts
from userland to apply CTM for more than one CRTC at a time and reject
matrices with scalars that we can't approximate without integer bits.

Signed-off-by: Stefan Schake <stschake@gmail.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Eric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/218067/

drivers/gpu/drm/vc4/vc4_drv.h

@@ -10,6 +10,7 @@
 #include <drm/drmP.h>
 #include <drm/drm_encoder.h>
 #include <drm/drm_gem_cma_helper.h>
+#include <drm/drm_atomic.h>
 
 #include "uapi/drm/vc4_drm.h"
 
@@ -193,6 +194,9 @@ struct vc4_dev {
 	} hangcheck;
 
 	struct semaphore async_modeset;
+
+	struct drm_modeset_lock ctm_state_lock;
+	struct drm_private_obj ctm_manager;
 };
 
 static inline struct vc4_dev *