[PATCH v1 1/4] drm/format-helper: Add XRGB8888 to UYVY conversion

[Ho Jie Feng <hjf3108@gmail.com>]

Add a helper for devices that use packed UYVY but accept XRGB8888
framebuffers.

Signed-off-by: Ho Jie Feng <hjf3108@gmail.com>
---
 drivers/gpu/drm/drm_format_helper.c   | 52 +++++++++++++++++++++++++++
 drivers/gpu/drm/drm_format_internal.h | 19 ++++++++++
 include/drm/drm_format_helper.h       |  4 +++
 3 files changed, 75 insertions(+)

diff --git a/drivers/gpu/drm/drm_format_helper.c b/drivers/gpu/drm/drm_format_helper.c
index 6cddf05c493bd..3cdfb4c68bfbf 100644
--- a/drivers/gpu/drm/drm_format_helper.c
+++ b/drivers/gpu/drm/drm_format_helper.c
@@ -11,6 +11,7 @@
 #include <linux/export.h>
 #include <linux/io.h>
 #include <linux/iosys-map.h>
+#include <linux/math.h>
 #include <linux/module.h>
 #include <linux/slab.h>
 
@@ -1379,3 +1380,54 @@ void drm_fb_xrgb8888_to_gray2(struct iosys_map *dst, const unsigned int *dst_pit
 }
 EXPORT_SYMBOL(drm_fb_xrgb8888_to_gray2);
 
+static void drm_fb_xrgb8888_to_uyvy_line(void *dbuf, const void *sbuf, unsigned int pixels)
+{
+	__le32 *dbuf32 = dbuf;
+	const __le32 *sbuf32 = sbuf;
+	const __le32 *send32 = sbuf32 + round_down(pixels, 2);
+
+	while (sbuf32 < send32) {
+		u32 pix1 = le32_to_cpup(sbuf32);
+		u32 pix2 = le32_to_cpup(sbuf32 + 1);
+		u32 val32 = drm_pixel_xrgb8888_to_uyvy_bt601(pix1, pix2);
+
+		*dbuf32++ = cpu_to_le32(val32);
+		sbuf32 += 2;
+	}
+}
+
+/**
+ * drm_fb_xrgb8888_to_uyvy - Convert XRGB8888 to UYVY clip buffer
+ * @dst: Array of UYVY destination buffers
+ * @dst_pitch: Array of numbers of bytes between the start of two consecutive scanlines
+ *             within @dst; can be NULL if scanlines are stored next to each other.
+ * @src: Array of XRGB8888 source buffers
+ * @fb: DRM framebuffer
+ * @clip: Clip rectangle area to copy; x1 and x2 must be even
+ * @state: Transform and conversion state
+ *
+ * This function copies parts of a framebuffer to display memory and converts the
+ * color format during the process. The parameters @dst, @dst_pitch and @src refer
+ * to arrays. Each array must have at least as many entries as there are planes in
+ * @fb's format. Each entry stores the value for the format's respective color plane
+ * at the same index.
+ *
+ * This function does not apply clipping on @dst (i.e. the destination is at the
+ * top-left corner).
+ *
+ * Drivers can use this function for UYVY devices that don't support XRGB8888
+ * natively. ITU BT.601 is being used for the RGB -> YUV conversion.
+ */
+void drm_fb_xrgb8888_to_uyvy(struct iosys_map *dst, const unsigned int *dst_pitch,
+			     const struct iosys_map *src, const struct drm_framebuffer *fb,
+			     const struct drm_rect *clip, struct drm_format_conv_state *state)
+{
+	static const u8 dst_pixsize[DRM_FORMAT_MAX_PLANES] = {
+		2,
+	};
+
+	drm_fb_xfrm(dst, dst_pitch, dst_pixsize, src, fb, clip, false, state,
+		    drm_fb_xrgb8888_to_uyvy_line);
+}
+EXPORT_SYMBOL(drm_fb_xrgb8888_to_uyvy);
+
diff --git a/drivers/gpu/drm/drm_format_internal.h b/drivers/gpu/drm/drm_format_internal.h
index ce29dd05bcc55..41875656e59e4 100644
--- a/drivers/gpu/drm/drm_format_internal.h
+++ b/drivers/gpu/drm/drm_format_internal.h
@@ -159,6 +159,25 @@ static inline u32 drm_pixel_xrgb8888_to_abgr2101010(u32 pix)
 	       drm_pixel_xrgb8888_to_xbgr2101010(pix);
 }
 
+static inline u32 drm_pixel_xrgb8888_to_uyvy_bt601(u32 pix1, u32 pix2)
+{
+	u32 r1 = (pix1 & 0x00ff0000) >> 16;
+	u32 g1 = (pix1 & 0x0000ff00) >> 8;
+	u32 b1 =  pix1 & 0x000000ff;
+	u32 r2 = (pix2 & 0x00ff0000) >> 16;
+	u32 g2 = (pix2 & 0x0000ff00) >> 8;
+	u32 b2 =  pix2 & 0x000000ff;
+	u32 r = r1 + r2;
+	u32 g = g1 + g2;
+	u32 b = b1 + b2;
+	u32 y1 = ((16U << 16) + 16829 * r1 + 33039 * g1 + 6416 * b1 + 32768) >> 16;
+	u32 y2 = ((16U << 16) + 16829 * r2 + 33039 * g2 + 6416 * b2 + 32768) >> 16;
+	u32 u = ((128U << 17) - 9714 * r - 19071 * g + 28784 * b + 65536) >> 17;
+	u32 v = ((128U << 17) + 28784 * r - 24103 * g - 4681 * b + 65536) >> 17;
+
+	return u | (y1 << 8) | (v << 16) | (y2 << 24);
+}
+
 /*
  * Conversion from ARGB8888
  */
diff --git a/include/drm/drm_format_helper.h b/include/drm/drm_format_helper.h
index 2b5c1aef80b0e..e50f96e07484c 100644
--- a/include/drm/drm_format_helper.h
+++ b/include/drm/drm_format_helper.h
@@ -136,4 +136,8 @@ void drm_fb_xrgb8888_to_gray2(struct iosys_map *dst, const unsigned int *dst_pit
 			      const struct iosys_map *src, const struct drm_framebuffer *fb,
 			      const struct drm_rect *clip, struct drm_format_conv_state *state);
 
+void drm_fb_xrgb8888_to_uyvy(struct iosys_map *dst, const unsigned int *dst_pitch,
+			     const struct iosys_map *src, const struct drm_framebuffer *fb,
+			     const struct drm_rect *clip, struct drm_format_conv_state *state);
+
 #endif /* __LINUX_DRM_FORMAT_HELPER_H */
-- 
2.55.0