[PATCH v3 1/9] drm/format-helper: Export drm_fb_clip_offset()

[Thomas Zimmermann]

Provide a function that computes the offset into a blit destination
buffer. This will allow to move destination-buffer clipping into the
format-helper callers.

v2:
	* provide documentation (Sam)
	* return 'unsigned int' (Sam, Noralf)

Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
Reviewed-by: Noralf Trønnes <noralf at tronnes.org>
---
 drivers/gpu/drm/drm_format_helper.c | 19 +++++++++++++++++--
 include/drm/drm_format_helper.h     |  4 ++++
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_format_helper.c b/drivers/gpu/drm/drm_format_helper.c
index 69fde60e36b3..677e62e39f72 100644
--- a/drivers/gpu/drm/drm_format_helper.c
+++ b/drivers/gpu/drm/drm_format_helper.c
@@ -17,12 +17,27 @@
 #include <drm/drm_fourcc.h>
 #include <drm/drm_rect.h>
 
-static unsigned int clip_offset(struct drm_rect *clip,
-				unsigned int pitch, unsigned int cpp)
+static unsigned int clip_offset(const struct drm_rect *clip, unsigned int pitch, unsigned int cpp)
 {
 	return clip->y1 * pitch + clip->x1 * cpp;
 }
 
+/**
+ * drm_fb_clip_offset - Returns the clipping rectangles byte-offset in a frambuffer
+ * pitch: Frambuffer line pitch in byte
+ * format: Frambuffer format
+ * clip: Clip rectangle
+ *
+ * Returns:
+ * The byte offset of the clip rectangle's top-left corner within the framebuffer.
+ */
+unsigned int drm_fb_clip_offset(unsigned int pitch, const struct drm_format_info *format,
+				const struct drm_rect *clip)
+{
+	return clip_offset(clip, pitch, format->cpp[0]);
+}
+EXPORT_SYMBOL(drm_fb_clip_offset);
+
 /**
  * drm_fb_memcpy - Copy clip buffer
  * @dst: Destination buffer
diff --git a/include/drm/drm_format_helper.h b/include/drm/drm_format_helper.h
index e86925cf07b9..f5a8b334b18d 100644
--- a/include/drm/drm_format_helper.h
+++ b/include/drm/drm_format_helper.h
@@ -6,9 +6,13 @@
 #ifndef __LINUX_DRM_FORMAT_HELPER_H
 #define __LINUX_DRM_FORMAT_HELPER_H
 
+struct drm_format_info;
 struct drm_framebuffer;
 struct drm_rect;
 
+unsigned int drm_fb_clip_offset(unsigned int pitch, const struct drm_format_info *format,
+				const struct drm_rect *clip);
+
 void drm_fb_memcpy(void *dst, void *vaddr, struct drm_framebuffer *fb,
 		   struct drm_rect *clip);
 void drm_fb_memcpy_dstclip(void __iomem *dst, unsigned int dst_pitch, void *vaddr,
-- 
2.33.1