mtd: add an ioctl to query the lock status of a flash sector

This patchs adds a way for user space programs to find out whether a
flash sector is locked. An optional driver method in the mtd_info struct
provides the information.

Signed-off-by: Richard Cochran <richard.cochran@omicron.at>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

drivers/mtd/mtdpart.c

@@ -264,6 +264,14 @@ static int part_unlock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
 	return part->master->unlock(part->master, ofs + part->offset, len);
 }
 
+static int part_is_locked(struct mtd_info *mtd, loff_t ofs, uint64_t len)
+{
+	struct mtd_part *part = PART(mtd);
+	if ((len + ofs) > mtd->size)
+		return -EINVAL;
+	return part->master->is_locked(part->master, ofs + part->offset, len);
+}
+
 static void part_sync(struct mtd_info *mtd)
 {
 	struct mtd_part *part = PART(mtd);
@@ -402,6 +410,8 @@ static struct mtd_part *add_one_partition(struct mtd_info *master,
 		slave->mtd.lock = part_lock;
 	if (master->unlock)
 		slave->mtd.unlock = part_unlock;
+	if (master->is_locked)
+		slave->mtd.is_locked = part_is_locked;
 	if (master->block_isbad)
 		slave->mtd.block_isbad = part_block_isbad;
 	if (master->block_markbad)