scsi: ibmvfc: Add helper for testing capability flags

Testing the NPIV Login response capabilities is a long winded process of
dereferencing the vhost->login_buf->resp.capabilities field, then byte
swapping that value to host endian, and performing the bitwise test.
Currently we only ever check this in ibmvfc_cancel_all(), but follow-up
patches will need to regularly check for targetWWPN and channelization
support.

Add a helper to simplify checking various VIOS capabilities, namely
ibmvfc_check_caps().

Link: https://lore.kernel.org/r/20201118011104.296999-4-tyreld@linux.ibm.comAcked-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: Tyrel Datwyler <tyreld@linux.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/ibmvscsi/ibmvfc.c

@@ -138,6 +138,13 @@ static void ibmvfc_tgt_move_login(struct ibmvfc_target *);
 
 static const char *unknown_error = "unknown error";
 
+static int ibmvfc_check_caps(struct ibmvfc_host *vhost, unsigned long cap_flags)
+{
+	u64 host_caps = be64_to_cpu(vhost->login_buf->resp.capabilities);
+
+	return (host_caps & cap_flags) ? 1 : 0;
+}
+
 #ifdef CONFIG_SCSI_IBMVFC_TRACE
 /**
  * ibmvfc_trc_start - Log a start trace entry
@@ -2240,7 +2247,7 @@ static int ibmvfc_cancel_all(struct scsi_device *sdev, int type)
 		tmf->common.length = cpu_to_be16(sizeof(*tmf));
 		tmf->scsi_id = cpu_to_be64(rport->port_id);
 		int_to_scsilun(sdev->lun, &tmf->lun);
-		if (!(be64_to_cpu(vhost->login_buf->resp.capabilities) & IBMVFC_CAN_SUPPRESS_ABTS))
+		if (!ibmvfc_check_caps(vhost, IBMVFC_CAN_SUPPRESS_ABTS))
 			type &= ~IBMVFC_TMF_SUPPRESS_ABTS;
 		if (vhost->state == IBMVFC_ACTIVE)
 			tmf->flags = cpu_to_be32((type | IBMVFC_TMF_LUA_VALID));