[PATCH v2] mtdchar: allow mmap() on MTD RAM/ROM char devices

[Anatolij Gustschin]

Signed-off-by: Anatolij Gustschin <agust at denx.de>
---
v1 -> v2:
 - Fixed compilation breakage on x86_64 while compiling
   as module, since on x86_64 phys_mem_access_prot() is
   not exported. Sorry for the breakage.

 drivers/mtd/mtdchar.c |   30 +++++++++++++++++++++++++++++-
 1 files changed, 29 insertions(+), 1 deletions(-)

diff --git a/drivers/mtd/mtdchar.c b/drivers/mtd/mtdchar.c
index c355491..db755a4 100644
--- a/drivers/mtd/mtdchar.c
+++ b/drivers/mtd/mtdchar.c
@@ -17,6 +17,7 @@
 #include <linux/compat.h>
 
 #include <linux/mtd/mtd.h>
+#include <linux/mtd/map.h>
 #include <linux/mtd/compatmac.h>
 
 #include <asm/uaccess.h>
@@ -925,9 +926,36 @@ 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) {
+		if (vma->vm_pgoff > (~0UL >> PAGE_SHIFT))
+			return -EINVAL;
+		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;
-- 
1.6.3.3