[S390] cio: obtain mdc value per channel path
Add support to accumulate the number of 64K-bytes blocks all paths
to a device at least support for a transport command.
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/drivers/s390/cio/device_ops.c b/drivers/s390/cio/device_ops.c
index 6da8454..651976b 100644
--- a/drivers/s390/cio/device_ops.c
+++ b/drivers/s390/cio/device_ops.c
@@ -687,6 +687,46 @@
EXPORT_SYMBOL(ccw_device_tm_start_timeout);
/**
+ * ccw_device_get_mdc - accumulate max data count
+ * @cdev: ccw device for which the max data count is accumulated
+ * @mask: mask of paths to use
+ *
+ * Return the number of 64K-bytes blocks all paths at least support
+ * for a transport command. Return values <= 0 indicate failures.
+ */
+int ccw_device_get_mdc(struct ccw_device *cdev, u8 mask)
+{
+ struct subchannel *sch = to_subchannel(cdev->dev.parent);
+ struct channel_path_desc_fmt1 desc;
+ struct chp_id chpid;
+ int mdc = 0, ret, i;
+
+ /* Adjust requested path mask to excluded varied off paths. */
+ if (mask)
+ mask &= sch->lpm;
+ else
+ mask = sch->lpm;
+
+ chp_id_init(&chpid);
+ for (i = 0; i < 8; i++) {
+ if (!(mask & (0x80 >> i)))
+ continue;
+ chpid.id = sch->schib.pmcw.chpid[i];
+ ret = chsc_determine_fmt1_channel_path_desc(chpid, &desc);
+ if (ret)
+ return ret;
+ if (!desc.f)
+ return 0;
+ if (!desc.r)
+ mdc = 1;
+ mdc = mdc ? min(mdc, (int)desc.mdc) : desc.mdc;
+ }
+
+ return mdc;
+}
+EXPORT_SYMBOL(ccw_device_get_mdc);
+
+/**
* ccw_device_tm_intrg - perform interrogate function
* @cdev: ccw device on which to perform the interrogate function
*
