drm: sti: add cursor plane

stih407 SoC have a dedicated hardware cursor plane,
this patch enable it.
The hardware have a color look up table, fix it to
be able to use ARGB8888.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>

drivers/gpu/drm/sti/sti_mixer.c

@@ -45,6 +45,7 @@ static const u32 mixerColorSpaceMatIdentity[] = {
 #define GAM_CTL_GDP1_MASK  BIT(4)
 #define GAM_CTL_GDP2_MASK  BIT(5)
 #define GAM_CTL_GDP3_MASK  BIT(6)
+#define GAM_CTL_CURSOR_MASK BIT(9)
 
 const char *sti_mixer_to_str(struct sti_mixer *mixer)
 {
@@ -127,6 +128,9 @@ int sti_mixer_set_layer_depth(struct sti_mixer *mixer, struct sti_layer *layer)
 	case STI_VID_1:
 		layer_id = GAM_DEPTH_VID1_ID;
 		break;
+	case STI_CURSOR:
+		/* no need to set depth for cursor */
+		return 0;
 	default:
 		DRM_ERROR("Unknown layer %d\n", layer->desc);
 		return 1;
@@ -188,6 +192,8 @@ static u32 sti_mixer_get_layer_mask(struct sti_layer *layer)
 		return GAM_CTL_VID0_MASK;
 	case STI_VID_1:
 		return GAM_CTL_VID1_MASK;
+	case STI_CURSOR:
+		return GAM_CTL_CURSOR_MASK;
 	default:
 		return 0;
 	}