[PATCH 1/5] drm/tinydrm: Add tinydrm_rgb565_buf_copy()

[Noralf Trønnes]

Add tinydrm_rgb565_buf_copy() function that copies buffer rectangle to
destination buffer and also handles XRGB8888 and byte swap conversions.
Useful for displays that only support RGB565 and can do partial updates.

Signed-off-by: Noralf Trønnes <noralf at tronnes.org>
---
 drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c | 56 +++++++++++++++++++++++++-
 include/drm/tinydrm/tinydrm-helpers.h          |  2 +
 2 files changed, 56 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c b/drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c
index d4cda33..e639453 100644
--- a/drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c
+++ b/drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c
@@ -7,13 +7,15 @@
  * (at your option) any later version.
  */
 
-#include <drm/tinydrm/tinydrm.h>
-#include <drm/tinydrm/tinydrm-helpers.h>
 #include <linux/backlight.h>
+#include <linux/dma-buf.h>
 #include <linux/pm.h>
 #include <linux/spi/spi.h>
 #include <linux/swab.h>
 
+#include <drm/tinydrm/tinydrm.h>
+#include <drm/tinydrm/tinydrm-helpers.h>
+
 static unsigned int spi_max;
 module_param(spi_max, uint, 0400);
 MODULE_PARM_DESC(spi_max, "Set a lower SPI max transfer size");
@@ -181,6 +183,56 @@ void tinydrm_xrgb8888_to_rgb565(u16 *dst, void *vaddr,
 EXPORT_SYMBOL(tinydrm_xrgb8888_to_rgb565);
 
 /**
+ * tinydrm_rgb565_buf_copy - Copy RGB565/XRGB8888 to RGB565 clip buffer
+ * @dst: RGB565 destination buffer
+ * @fb: DRM framebuffer
+ * @clip: Clip rectangle area to copy
+ * @swap: Swap bytes
+ *
+ * Returns:
+ * Zero on success, negative error code on failure.
+ */
+int tinydrm_rgb565_buf_copy(void *dst, struct drm_framebuffer *fb,
+			    struct drm_clip_rect *clip, bool swap)
+{
+	struct drm_gem_cma_object *cma_obj = drm_fb_cma_get_gem_obj(fb, 0);
+	struct dma_buf_attachment *import_attach = cma_obj->base.import_attach;
+	struct drm_format_name_buf format_name;
+	void *src = cma_obj->vaddr;
+	int ret = 0;
+
+	if (import_attach) {
+		ret = dma_buf_begin_cpu_access(import_attach->dmabuf,
+					       DMA_FROM_DEVICE);
+		if (ret)
+			return ret;
+	}
+
+	switch (fb->format->format) {
+	case DRM_FORMAT_RGB565:
+		if (swap)
+			tinydrm_swab16(dst, src, fb, clip);
+		else
+			tinydrm_memcpy(dst, src, fb, clip);
+		break;
+	case DRM_FORMAT_XRGB8888:
+		tinydrm_xrgb8888_to_rgb565(dst, src, fb, clip, swap);
+		break;
+	default:
+		dev_err_once(fb->dev->dev, "Format is not supported: %s\n",
+			     drm_get_format_name(fb->format->format,
+						 &format_name));
+		return -EINVAL;
+	}
+
+	if (import_attach)
+		ret = dma_buf_end_cpu_access(import_attach->dmabuf,
+					     DMA_FROM_DEVICE);
+	return ret;
+}
+EXPORT_SYMBOL(tinydrm_rgb565_buf_copy);
+
+/**
  * tinydrm_of_find_backlight - Find backlight device in device-tree
  * @dev: Device
  *
diff --git a/include/drm/tinydrm/tinydrm-helpers.h b/include/drm/tinydrm/tinydrm-helpers.h
index 9b9b6cf..d1f6722 100644
--- a/include/drm/tinydrm/tinydrm-helpers.h
+++ b/include/drm/tinydrm/tinydrm-helpers.h
@@ -43,6 +43,8 @@ void tinydrm_swab16(u16 *dst, void *vaddr, struct drm_framebuffer *fb,
 void tinydrm_xrgb8888_to_rgb565(u16 *dst, void *vaddr,
 				struct drm_framebuffer *fb,
 				struct drm_clip_rect *clip, bool swap);
+int tinydrm_rgb565_buf_copy(void *dst, struct drm_framebuffer *fb,
+			    struct drm_clip_rect *clip, bool swap);
 
 struct backlight_device *tinydrm_of_find_backlight(struct device *dev);
 int tinydrm_enable_backlight(struct backlight_device *backlight);
-- 
2.10.2