s390/dasd: add device ping attribute
Add a function to check if a device is accessible.
This makes mostly sense for copy pair secondary devices but it will work
for all devices.
The sysfs attribute ping is a write only attribute and will issue a NOP
CCW to the device.
In case of success it will return zero. If the device is not accessible
it will return an error code.
Signed-off-by: Stefan Haberland <sth@linux.ibm.com>
Reviewed-by: Jan Hoeppner <hoeppner@linux.ibm.com>
Link: https://lore.kernel.org/r/20220920192616.808070-8-sth@linux.ibm.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/drivers/s390/block/dasd_eckd.h b/drivers/s390/block/dasd_eckd.h
index 4da9d03..f9299bd 100644
--- a/drivers/s390/block/dasd_eckd.h
+++ b/drivers/s390/block/dasd_eckd.h
@@ -13,6 +13,7 @@
/*****************************************************************************
* SECTION: CCW Definitions
****************************************************************************/
+#define DASD_ECKD_CCW_NOP 0x03
#define DASD_ECKD_CCW_WRITE 0x05
#define DASD_ECKD_CCW_READ 0x06
#define DASD_ECKD_CCW_WRITE_HOME_ADDRESS 0x09
