On 9/5/06, David Howells <[email protected]> wrote:
Make it possible to mmap MTD chardevs directly or by copy on a NOMMU system.
Why would you want to do this? I'm just curious.
+/*
+ * Allow NOMMU mmap() to directly map the device (if not NULL)
+ * - return the address to which the offset maps
+ * - return -ENOSYS to indicate refusal to do the mapping
Where do you actually do the -ENOSYS part? I think that comment
belongs to the actual mtd_get_unmapped_area call in mtdchar.c, no?
+/*
+ * try to determine where a shared mapping can be made
+ * - only supported for NOMMU at the moment (MMU can't doesn't copy private
+ * mappings)
+ */
+#ifndef CONFIG_MMU
+static unsigned long mtd_get_unmapped_area(struct file *file,
+ unsigned long addr,
+ unsigned long len,
+ unsigned long pgoff,
+ unsigned long flags)
+{
+ struct mtd_file_info *mfi = file->private_data;
+ struct mtd_info *mtd = mfi->mtd;
+
+ if (mtd->get_unmapped_area) {
+ unsigned long offset;
+
+ if (addr != 0)
+ return (unsigned long) -EINVAL;
+
+ if (len > mtd->size || pgoff >= (mtd->size >> PAGE_SHIFT))
+ return (unsigned long) -EINVAL;
+
+ offset = pgoff << PAGE_SHIFT;
+ if (offset > mtd->size - len)
+ return (unsigned long) -EINVAL;
+
+ return mtd->get_unmapped_area(mtd, len, offset, flags);
+ }
+
+ /* can't map directly */
+ return (unsigned long) -ENOSYS;
+}
+#endif
Could we do something like:
#else
#define mtd_get_unmapped_area (NULL);
which would prevent the ugly ifdef in the mtd_fops structure?
static struct file_operations mtd_fops = {
.owner = THIS_MODULE,
.llseek = mtd_lseek,
@@ -771,6 +864,10 @@ static struct file_operations mtd_fops =
.ioctl = mtd_ioctl,
.open = mtd_open,
.release = mtd_close,
+ .mmap = mtd_mmap,
+#ifndef CONFIG_MMU
+ .get_unmapped_area = mtd_get_unmapped_area,
+#endif
See above.
josh
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
