mtd: concat: implement _is_locked mtd operation

Add an implementation of the _is_locked operation for concatenated mtd
devices. This doesn't handle getting the lock status of a range that
spans chips, which is consistent with cfi_ppb_is_locked and
cfi_intelext_is_locked which only look at the first block in the range.
Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Signed-off-by: Richard Weinberger <richard@nod.at>

drivers/mtd/mtdconcat.c

@@ -485,6 +485,28 @@ static int concat_unlock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
 	return concat_xxlock(mtd, ofs, len, false);
 }
 
+static int concat_is_locked(struct mtd_info *mtd, loff_t ofs, uint64_t len)
+{
+	struct mtd_concat *concat = CONCAT(mtd);
+	int i, err = -EINVAL;
+
+	for (i = 0; i < concat->num_subdev; i++) {
+		struct mtd_info *subdev = concat->subdev[i];
+
+		if (ofs >= subdev->size) {
+			ofs -= subdev->size;
+			continue;
+		}
+
+		if (ofs + len > subdev->size)
+			break;
+
+		return mtd_is_locked(subdev, ofs, len);
+	}
+
+	return err;
+}
+
 static void concat_sync(struct mtd_info *mtd)
 {
 	struct mtd_concat *concat = CONCAT(mtd);
@@ -684,6 +706,7 @@ struct mtd_info *mtd_concat_create(struct mtd_info *subdev[],	/* subdevices to c
 	concat->mtd._sync = concat_sync;
 	concat->mtd._lock = concat_lock;
 	concat->mtd._unlock = concat_unlock;
+	concat->mtd._is_locked = concat_is_locked;
 	concat->mtd._suspend = concat_suspend;
 	concat->mtd._resume = concat_resume;