acornfb: remove fb_mmap function

The driver's fb_mmap function is essentially the same as a generic fb_mmap
function.  Delete driver's function and use the generic one.

A difference is that generic function marks frame buffer memory as VM_IO |
VM_RESERVED.  The driver's function marks it as VM_IO only.
Signed-off-by: NKrzysztof Helt <krzysztof.h1@wp.pl>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/video/acornfb.c

@@ -859,43 +859,6 @@ acornfb_pan_display(struct fb_var_screeninfo *var, struct fb_info *info)
 	return 0;
 }
 
-/*
- * Note that we are entered with the kernel locked.
- */
-static int
-acornfb_mmap(struct fb_info *info, struct vm_area_struct *vma)
-{
-	unsigned long off, start;
-	u32 len;
-
-	off = vma->vm_pgoff << PAGE_SHIFT;
-
-	start = info->fix.smem_start;
-	len = PAGE_ALIGN(start & ~PAGE_MASK) + info->fix.smem_len;
-	start &= PAGE_MASK;
-	if ((vma->vm_end - vma->vm_start + off) > len)
-		return -EINVAL;
-	off += start;
-	vma->vm_pgoff = off >> PAGE_SHIFT;
-
-	/* This is an IO map - tell maydump to skip this VMA */
-	vma->vm_flags |= VM_IO;
-
-	vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
-
-	/*
-	 * Don't alter the page protection flags; we want to keep the area
-	 * cached for better performance.  This does mean that we may miss
-	 * some updates to the screen occasionally, but process switches
-	 * should cause the caches and buffers to be flushed often enough.
-	 */
-	if (io_remap_pfn_range(vma, vma->vm_start, off >> PAGE_SHIFT,
-				vma->vm_end - vma->vm_start,
-				vma->vm_page_prot))
-		return -EAGAIN;
-	return 0;
-}
-
 static struct fb_ops acornfb_ops = {
 	.owner		= THIS_MODULE,
 	.fb_check_var	= acornfb_check_var,
@@ -905,7 +868,6 @@ static struct fb_ops acornfb_ops = {
 	.fb_fillrect	= cfb_fillrect,
 	.fb_copyarea	= cfb_copyarea,
 	.fb_imageblit	= cfb_imageblit,
-	.fb_mmap	= acornfb_mmap,
 };
 
 /*