[MTD] driver model updates

Update driver model support in the MTD framework, so it fits
better into the current udev-based hotplug framework:

 - Each mtd_info now has a device node.  MTD drivers should set
   the dev.parent field to point to the physical device, before
   setting up partitions or otherwise declaring MTDs.

 - Those device nodes always map to /sys/class/mtdX device nodes,
   which no longer depend on MTD_CHARDEV.

 - Those mtdX sysfs nodes have a "starter set" of attributes;
   it's not yet sufficient to replace /proc/mtd.

 - Enabling MTD_CHARDEV provides /sys/class/mtdXro/ nodes and the
   /sys/class/mtd*/dev attributes (for udev, mdev, etc).

 - Include a MODULE_ALIAS_CHARDEV_MAJOR macro.  It'll work with
   udev creating the /dev/mtd* nodes, not just a static rootfs.

So the sysfs structure is pretty much what you'd expect, except
that readonly chardev nodes are a bit quirky.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 8 insertions, 1 deletions

diff --git a/drivers/mtd/mtdpart.c b/drivers/mtd/mtdpart.c
index 06d5b9d8853a..02ce38fb1fc3 100644
--- a/drivers/mtd/mtdpart.c
+++ b/drivers/mtd/mtdpart.c
@@ -356,6 +356,11 @@ static struct mtd_part *add_one_partition(struct mtd_info *master,
         slave->mtd.owner = master->owner;
         slave->mtd.backing_dev_info = master->backing_dev_info;
 
+        /* NOTE:  we don't arrange MTDs as a tree; it'd be error-prone
+         * to have the same data be in two different partitions.
+         */
+        slave->mtd.dev.parent = master->dev.parent;
+
         slave->mtd.read = part_read;
         slave->mtd.write = part_write;
 
@@ -508,7 +513,9 @@ out_register:
  * This function, given a master MTD object and a partition table, creates
  * and registers slave MTD objects which are bound to the master according to
  * the partition definitions.
- * (Q: should we register the master MTD object as well?)
+ *
+ * We don't register the master, or expect the caller to have done so,
+ * for reasons of data integrity.
  */
 
 int add_mtd_partitions(struct mtd_info *master,