drm/format-helper: Add blitter functions

The blitter functions copy a framebuffer to I/O memory using one of
the existing conversion functions.

Signed-off-by: Thomas Zimmermann <[e-mail]>
Reviewed-by: Daniel Vetter <[e-mail]>
Acked-by: Maxime Ripard <[e-mail]>
Tested-by: nerdopolis <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/drm_format_helper.c

···
 }
 EXPORT_SYMBOL(drm_fb_xrgb8888_to_gray8);
 
+/**
+ * drm_fb_blit_rect_dstclip - Copy parts of a framebuffer to display memory
+ * @dst:	The display memory to copy to
+ * @dst_pitch:	Number of bytes between two consecutive scanlines within dst
+ * @dst_format:	FOURCC code of the display's color format
+ * @vmap:	The framebuffer memory to copy from
+ * @fb:		The framebuffer to copy from
+ * @clip:	Clip rectangle area to copy
+ *
+ * This function copies parts of a framebuffer to display memory. If the
+ * formats of the display and the framebuffer mismatch, the blit function
+ * will attempt to convert between them.
+ *
+ * Use drm_fb_blit_dstclip() to copy the full framebuffer.
+ *
+ * Returns:
+ * 0 on success, or
+ * -EINVAL if the color-format conversion failed, or
+ * a negative error code otherwise.
+ */
+int drm_fb_blit_rect_dstclip(void __iomem *dst, unsigned int dst_pitch,
+			     uint32_t dst_format, void *vmap,
+			     struct drm_framebuffer *fb,
+			     struct drm_rect *clip)
+{
+	uint32_t fb_format = fb->format->format;
+
+	/* treat alpha channel like filler bits */
+	if (fb_format == DRM_FORMAT_ARGB8888)
+		fb_format = DRM_FORMAT_XRGB8888;
+	if (dst_format == DRM_FORMAT_ARGB8888)
+		dst_format = DRM_FORMAT_XRGB8888;
+
+	if (dst_format == fb_format) {
+		drm_fb_memcpy_dstclip(dst, dst_pitch, vmap, fb, clip);
+		return 0;
+
+	} else if (dst_format == DRM_FORMAT_RGB565) {
+		if (fb_format == DRM_FORMAT_XRGB8888) {
+			drm_fb_xrgb8888_to_rgb565_dstclip(dst, dst_pitch,
+							  vmap, fb, clip,
+							  false);
+			return 0;
+		}
+	} else if (dst_format == DRM_FORMAT_RGB888) {
+		if (fb_format == DRM_FORMAT_XRGB8888) {
+			drm_fb_xrgb8888_to_rgb888_dstclip(dst, dst_pitch,
+							  vmap, fb, clip);
+			return 0;
+		}
+	}
+
+	return -EINVAL;
+}
+EXPORT_SYMBOL(drm_fb_blit_rect_dstclip);
+
+/**
+ * drm_fb_blit_dstclip - Copy framebuffer to display memory
+ * @dst:	The display memory to copy to
+ * @dst_pitch:	Number of bytes between two consecutive scanlines within dst
+ * @dst_format:	FOURCC code of the display's color format
+ * @vmap:	The framebuffer memory to copy from
+ * @fb:		The framebuffer to copy from
+ *
+ * This function copies a full framebuffer to display memory. If the formats
+ * of the display and the framebuffer mismatch, the copy function will
+ * attempt to convert between them.
+ *
+ * See drm_fb_blit_rect_dstclip() for more inforamtion.
+ *
+ * Returns:
+ * 0 on success, or a negative error code otherwise.
+ */
+int drm_fb_blit_dstclip(void __iomem *dst, unsigned int dst_pitch,
+			uint32_t dst_format, void *vmap,
+			struct drm_framebuffer *fb)
+{
+	struct drm_rect fullscreen = {
+		.x1 = 0,
+		.x2 = fb->width,
+		.y1 = 0,
+		.y2 = fb->height,
+	};
+	return drm_fb_blit_rect_dstclip(dst, dst_pitch, dst_format, vmap, fb,
+					&fullscreen);
+}
+EXPORT_SYMBOL(drm_fb_blit_dstclip);

include/drm/drm_format_helper.h

···
 void drm_fb_xrgb8888_to_gray8(u8 *dst, void *vaddr, struct drm_framebuffer *fb,
 			      struct drm_rect *clip);
 
+int drm_fb_blit_rect_dstclip(void __iomem *dst, unsigned int dst_pitch,
+			     uint32_t dst_format, void *vmap,
+			     struct drm_framebuffer *fb,
+			     struct drm_rect *rect);
+int drm_fb_blit_dstclip(void __iomem *dst, unsigned int dst_pitch,
+			uint32_t dst_format, void *vmap,
+			struct drm_framebuffer *fb);
+
 #endif /* __LINUX_DRM_FORMAT_HELPER_H */