[SCSI] usb-storage: add support for write cache quirk

Add support for write cache quirk on usb hdd. scsi driver will be set to wce
by detecting write cache quirk in quirk list when plugging usb hdd.

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Pankaj Kumar <pankaj.km@samsung.com>
Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/include/linux/usb_usual.h b/include/linux/usb_usual.h
index 17df3600bcef..e84e769aaddc 100644
--- a/include/linux/usb_usual.h
+++ b/include/linux/usb_usual.h
@@ -64,7 +64,9 @@
         US_FLAG(NO_READ_CAPACITY_16,    0x00080000)             \
                 /* cannot handle READ_CAPACITY_16 */            \
         US_FLAG(INITIAL_READ10, 0x00100000)                     \
-                /* Initial READ(10) (and others) must be retried */
+                /* Initial READ(10) (and others) must be retried */     \
+        US_FLAG(WRITE_CACHE,    0x00200000)                     \
+                /* Write Cache status is not available */
 
 #define US_FLAG(name, value)    US_FL_##name = value ,
 enum { US_DO_ALL_FLAGS };