drm/exynos: Support multi buffers

These formats(NV12M, NV12MT and YUV420M) have non contiguous  multi
planes, so each plane uses different buffer. The exynos drm should
support multi buffer for them.

Signed-off-by: Seung-Woo Kim <sw0312.kim@samsung.com>
Signed-off-by: Joonyoung Shim <jy0922.shim@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
diff --git a/drivers/gpu/drm/exynos/exynos_drm_fb.h b/drivers/gpu/drm/exynos/exynos_drm_fb.h
index 8b3e12f..3ecb30d 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_fb.h
+++ b/drivers/gpu/drm/exynos/exynos_drm_fb.h
@@ -28,11 +28,28 @@
 #ifndef _EXYNOS_DRM_FB_H_
 #define _EXYNOS_DRM_FB_H
 
+static inline int exynos_drm_format_num_buffers(uint32_t format)
+{
+	switch (format) {
+	case DRM_FORMAT_NV12M:
+	case DRM_FORMAT_NV12MT:
+		return 2;
+	case DRM_FORMAT_YUV420M:
+		return 3;
+	default:
+		return 1;
+	}
+}
+
 struct drm_framebuffer *
 exynos_drm_framebuffer_init(struct drm_device *dev,
 			    struct drm_mode_fb_cmd2 *mode_cmd,
 			    struct drm_gem_object *obj);
 
+/* get memory information of a drm framebuffer */
+struct exynos_drm_gem_buf *exynos_drm_fb_buffer(struct drm_framebuffer *fb,
+						 int index);
+
 void exynos_drm_mode_config_init(struct drm_device *dev);
 
 #endif