drm/format-helper: Support the AB24/XB24 formats

Add a conversion helper for the AB24 and XB24 formats to use in
drm_fb_blit().
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230120173103.4002342-7-thierry.reding@gmail.com

drivers/gpu/drm/drm_format_helper.c

@@ -649,6 +649,66 @@ void drm_fb_xrgb8888_to_argb8888(struct iosys_map *dst, const unsigned int *dst_
 }
 EXPORT_SYMBOL(drm_fb_xrgb8888_to_argb8888);
 
+static void drm_fb_xrgb8888_to_abgr8888_line(void *dbuf, const void *sbuf, unsigned int pixels)
+{
+	__le32 *dbuf32 = dbuf;
+	const __le32 *sbuf32 = sbuf;
+	unsigned int x;
+	u32 pix;
+
+	for (x = 0; x < pixels; x++) {
+		pix = le32_to_cpu(sbuf32[x]);
+		pix = ((pix & 0x00ff0000) >> 16) <<  0 |
+		      ((pix & 0x0000ff00) >>  8) <<  8 |
+		      ((pix & 0x000000ff) >>  0) << 16 |
+		      GENMASK(31, 24); /* fill alpha bits */
+		*dbuf32++ = cpu_to_le32(pix);
+	}
+}
+
+static void drm_fb_xrgb8888_to_abgr8888(struct iosys_map *dst, const unsigned int *dst_pitch,
+					const struct iosys_map *src,
+					const struct drm_framebuffer *fb,
+					const struct drm_rect *clip)
+{
+	static const u8 dst_pixsize[DRM_FORMAT_MAX_PLANES] = {
+		4,
+	};
+
+	drm_fb_xfrm(dst, dst_pitch, dst_pixsize, src, fb, clip, false,
+		    drm_fb_xrgb8888_to_abgr8888_line);
+}
+
+static void drm_fb_xrgb8888_to_xbgr8888_line(void *dbuf, const void *sbuf, unsigned int pixels)
+{
+	__le32 *dbuf32 = dbuf;
+	const __le32 *sbuf32 = sbuf;
+	unsigned int x;
+	u32 pix;
+
+	for (x = 0; x < pixels; x++) {
+		pix = le32_to_cpu(sbuf32[x]);
+		pix = ((pix & 0x00ff0000) >> 16) <<  0 |
+		      ((pix & 0x0000ff00) >>  8) <<  8 |
+		      ((pix & 0x000000ff) >>  0) << 16 |
+		      ((pix & 0xff000000) >> 24) << 24;
+		*dbuf32++ = cpu_to_le32(pix);
+	}
+}
+
+static void drm_fb_xrgb8888_to_xbgr8888(struct iosys_map *dst, const unsigned int *dst_pitch,
+					const struct iosys_map *src,
+					const struct drm_framebuffer *fb,
+					const struct drm_rect *clip)
+{
+	static const u8 dst_pixsize[DRM_FORMAT_MAX_PLANES] = {
+		4,
+	};
+
+	drm_fb_xfrm(dst, dst_pitch, dst_pixsize, src, fb, clip, false,
+		    drm_fb_xrgb8888_to_xbgr8888_line);
+}
+
 static void drm_fb_xrgb8888_to_xrgb2101010_line(void *dbuf, const void *sbuf, unsigned int pixels)
 {
 	__le32 *dbuf32 = dbuf;
@@ -868,6 +928,12 @@ int drm_fb_blit(struct iosys_map *dst, const unsigned int *dst_pitch, uint32_t d
 		} else if (dst_format == DRM_FORMAT_ARGB8888) {
 			drm_fb_xrgb8888_to_argb8888(dst, dst_pitch, src, fb, clip);
 			return 0;
+		} else if (dst_format == DRM_FORMAT_XBGR8888) {
+			drm_fb_xrgb8888_to_xbgr8888(dst, dst_pitch, src, fb, clip);
+			return 0;
+		} else if (dst_format == DRM_FORMAT_ABGR8888) {
+			drm_fb_xrgb8888_to_abgr8888(dst, dst_pitch, src, fb, clip);
+			return 0;
 		} else if (dst_format == DRM_FORMAT_XRGB2101010) {
 			drm_fb_xrgb8888_to_xrgb2101010(dst, dst_pitch, src, fb, clip);
 			return 0;