drm/fb_helper: Create wrappers for fb_sys_read/write funcs

Some drm drivers populate their fb_ops with fb_sys_read/write fb sysfs
ops.

Create a drm_fb_helper function that wraps around these calls.

This is part of an effort to prevent drm drivers from calling fbdev
functions directly, in order to make fbdev emulation a top level drm
option.

v3:
- Fix kerneldoc errors

v2:
- Added kerneldocs
- Follow the drm way of aligning of arguments in func definitions
- Remove unnecessary checks for non NULL fb_info

Signed-off-by: Archit Taneja <architt@codeaurora.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/drm_fb_helper.c

@@ -761,6 +761,38 @@ void drm_fb_helper_unlink_fbi(struct drm_fb_helper *fb_helper)
 }
 EXPORT_SYMBOL(drm_fb_helper_unlink_fbi);
 
+/**
+ * drm_fb_helper_sys_read - wrapper around fb_sys_read
+ * @info: fb_info struct pointer
+ * @buf: userspace buffer to read from framebuffer memory
+ * @count: number of bytes to read from framebuffer memory
+ * @ppos: read offset within framebuffer memory
+ *
+ * A wrapper around fb_sys_read implemented by fbdev core
+ */
+ssize_t drm_fb_helper_sys_read(struct fb_info *info, char __user *buf,
+			       size_t count, loff_t *ppos)
+{
+	return fb_sys_read(info, buf, count, ppos);
+}
+EXPORT_SYMBOL(drm_fb_helper_sys_read);
+
+/**
+ * drm_fb_helper_sys_write - wrapper around fb_sys_write
+ * @info: fb_info struct pointer
+ * @buf: userspace buffer to write to framebuffer memory
+ * @count: number of bytes to write to framebuffer memory
+ * @ppos: write offset within framebuffer memory
+ *
+ * A wrapper around fb_sys_write implemented by fbdev core
+ */
+ssize_t drm_fb_helper_sys_write(struct fb_info *info, const char __user *buf,
+				size_t count, loff_t *ppos)
+{
+	return fb_sys_write(info, buf, count, ppos);
+}
+EXPORT_SYMBOL(drm_fb_helper_sys_write);
+
 static int setcolreg(struct drm_crtc *crtc, u16 red, u16 green,
 		     u16 blue, u16 regno, struct fb_info *info)
 {