mtd: mtdchar: fix mmap for MTD RAM/ROM char devices

For no-mmu systems mmap() on RAM/ROM devices already works
but for systems with mmu it probably was not tested and
doesn't work.

This patch allows using mmap() on MTD RAM/ROM devices on systems
with MMU. It has been tested on mpc5121e based platform with
MR0A16A MRAM device attached over LocalBus.

Signed-off-by: Anatolij Gustschin <agust@denx.de>
Acked-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 27 insertions, 1 deletions

diff --git a/drivers/mtd/mtdchar.c b/drivers/mtd/mtdchar.c
index a8e69dd2b2e4..c27e65e3e291 100644
--- a/drivers/mtd/mtdchar.c
+++ b/drivers/mtd/mtdchar.c
@@ -18,6 +18,7 @@
 #include <linux/mount.h>
 
 #include <linux/mtd/mtd.h>
+#include <linux/mtd/map.h>
 #include <linux/mtd/compatmac.h>
 
 #include <asm/uaccess.h>
@@ -955,9 +956,34 @@ static int mtd_mmap(struct file *file, struct vm_area_struct *vma)
 #ifdef CONFIG_MMU
         struct mtd_file_info *mfi = file->private_data;
         struct mtd_info *mtd = mfi->mtd;
+        struct map_info *map = mtd->priv;
+        unsigned long start;
+        unsigned long off;
+        u32 len;
+
+        if (mtd->type == MTD_RAM || mtd->type == MTD_ROM) {
+                off = vma->vm_pgoff << PAGE_SHIFT;
+                start = map->phys;
+                len = PAGE_ALIGN((start & ~PAGE_MASK) + map->size);
+                start &= PAGE_MASK;
+                if ((vma->vm_end - vma->vm_start + off) > len)
+                        return -EINVAL;
+
+                off += start;
+                vma->vm_pgoff = off >> PAGE_SHIFT;
+                vma->vm_flags |= VM_IO | VM_RESERVED;
+
+#ifdef pgprot_noncached
+                if (file->f_flags & O_DSYNC || off >= __pa(high_memory))
+                        vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+#endif
+                if (io_remap_pfn_range(vma, vma->vm_start, off >> PAGE_SHIFT,
+                                       vma->vm_end - vma->vm_start,
+                                       vma->vm_page_prot))
+                        return -EAGAIN;
 
-        if (mtd->type == MTD_RAM || mtd->type == MTD_ROM)
                 return 0;
+        }
         return -ENOSYS;
 #else
         return vma->vm_flags & VM_SHARED ? 0 : -ENOSYS;