fbdev: add fb_read/fb_write functions for framebuffers in system RAM

The functions fb_read() and fb_write in fbmem.c assume that the framebuffer
is in IO memory.  However, we have 3 drivers (hecubafb, arcfb, and vfb)
where the framebuffer is allocated from system RAM (via vmalloc). Using
__raw_read/__raw_write (fb_readl/fb_writel) for these drivers is
illegal, especially in other platforms.

Create file read and write methods for these types of drivers.  These are
named fb_sys_read() and fb_sys_write().

Signed-off-by: Antonino Daplas <adaplas@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/include/linux/fb.h b/include/linux/fb.h
index acb6ddb68fa2..70d154a02c5c 100644
--- a/include/linux/fb.h
+++ b/include/linux/fb.h
@@ -903,6 +903,10 @@ extern void cfb_imageblit(struct fb_info *info, const struct fb_image *image);
 extern void sys_fillrect(struct fb_info *info, const struct fb_fillrect *rect);
 extern void sys_copyarea(struct fb_info *info, const struct fb_copyarea *area);
 extern void sys_imageblit(struct fb_info *info, const struct fb_image *image);
+extern ssize_t fb_sys_read(struct fb_info *info, char __user *buf,
+                           size_t count, loff_t *ppos);
+extern ssize_t fb_sys_write(struct fb_info *info, const char __user *buf,
+                            size_t count, loff_t *ppos);
 
 /* drivers/video/fbmem.c */
 extern int register_framebuffer(struct fb_info *fb_info);