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>
diff --git a/drivers/mtd/mtdchar.c b/drivers/mtd/mtdchar.c
index 8b223c0..a8e69dd 100644
--- a/drivers/mtd/mtdchar.c
+++ b/drivers/mtd/mtdchar.c
@@ -676,6 +676,20 @@
 		break;
 	}
 
+	case MEMISLOCKED:
+	{
+		struct erase_info_user einfo;
+
+		if (copy_from_user(&einfo, argp, sizeof(einfo)))
+			return -EFAULT;
+
+		if (!mtd->is_locked)
+			ret = -EOPNOTSUPP;
+		else
+			ret = mtd->is_locked(mtd, einfo.start, einfo.length);
+		break;
+	}
+
 	/* Legacy interface */
 	case MEMGETOOBSEL:
 	{