scsi: qla2xxx: Honor status qualifier in FCP_RSP per spec

FCP-4 (referred FCP-4 rev-2b) identifies the earlier known "retry delay
timer" field as "status qualifier", which is described in SAM-5 and later
specs. This fix makes appropriate driver side modifications to honor the
new definition. The SAM document referred was SAM-6 rev-5.

Link: https://lore.kernel.org/r/20200904045128.23631-5-njavali@marvell.com
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Arun Easi <aeasi@marvell.com>
Signed-off-by: Himanshu Madhani <hmadhani@marvell.com>
Signed-off-by: Nilesh Javali <njavali@marvell.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/qla2xxx/qla_fw.h

@@ -619,7 +619,7 @@ struct sts_entry_24xx {
 #define SF_NVME_ERSP            BIT_6
 #define SF_FCP_RSP_DMA		BIT_0
 
-	__le16	retry_delay;
+	__le16	status_qualifier;
 	__le16	scsi_status;		/* SCSI status. */
 #define SS_CONFIRMATION_REQ		BIT_12
 

drivers/scsi/qla2xxx/qla_inline.h

@@ -271,11 +271,41 @@ qla2x00_handle_mbx_completion(struct qla_hw_data *ha, int status)
 }
 
 static inline void
-qla2x00_set_retry_delay_timestamp(fc_port_t *fcport, uint16_t retry_delay)
+qla2x00_set_retry_delay_timestamp(fc_port_t *fcport, uint16_t sts_qual)
 {
-	if (retry_delay)
-		fcport->retry_delay_timestamp = jiffies +
-		    (retry_delay * HZ / 10);
+	u8 scope;
+	u16 qual;
+#define SQ_SCOPE_MASK		0xc000 /* SAM-6 rev5 5.3.2 */
+#define SQ_SCOPE_SHIFT		14
+#define SQ_QUAL_MASK		0x3fff
+
+#define SQ_MAX_WAIT_SEC		60 /* Max I/O hold off time in seconds. */
+#define SQ_MAX_WAIT_TIME	(SQ_MAX_WAIT_SEC * 10) /* in 100ms. */
+
+	if (!sts_qual) /* Common case. */
+		return;
+
+	scope = (sts_qual & SQ_SCOPE_MASK) >> SQ_SCOPE_SHIFT;
+	/* Handle only scope 1 or 2, which is for I-T nexus. */
+	if (scope != 1 && scope != 2)
+		return;
+
+	/* Skip processing, if retry delay timer is already in effect. */
+	if (fcport->retry_delay_timestamp &&
+	    time_before(jiffies, fcport->retry_delay_timestamp))
+		return;
+
+	qual = sts_qual & SQ_QUAL_MASK;
+	if (qual < 1 || qual > 0x3fef)
+		return;
+	qual = min(qual, (u16)SQ_MAX_WAIT_TIME);
+
+	/* qual is expressed in 100ms increments. */
+	fcport->retry_delay_timestamp = jiffies + (qual * HZ / 10);
+
+	ql_log(ql_log_warn, fcport->vha, 0x5101,
+	       "%8phC: I/O throttling requested (status qualifier = %04xh), holding off I/Os for %ums.\n",
+	       fcport->port_name, sts_qual, qual * 100);
 }
 
 static inline bool

drivers/scsi/qla2xxx/qla_isr.c

@@ -2855,7 +2855,7 @@ qla2x00_status_entry(scsi_qla_host_t *vha, struct rsp_que *rsp, void *pkt)
 	int logit = 1;
 	int res = 0;
 	uint16_t state_flags = 0;
-	uint16_t retry_delay = 0;
+	uint16_t sts_qual = 0;
 
 	if (IS_FWI2_CAPABLE(ha)) {
 		comp_status = le16_to_cpu(sts24->comp_status);
@@ -2953,8 +2953,6 @@ qla2x00_status_entry(scsi_qla_host_t *vha, struct rsp_que *rsp, void *pkt)
 	sense_len = par_sense_len = rsp_info_len = resid_len =
 	    fw_resid_len = 0;
 	if (IS_FWI2_CAPABLE(ha)) {
-		u16 sts24_retry_delay = le16_to_cpu(sts24->retry_delay);
-
 		if (scsi_status & SS_SENSE_LEN_VALID)
 			sense_len = le32_to_cpu(sts24->sense_len);
 		if (scsi_status & SS_RESPONSE_INFO_LEN_VALID)
@@ -2968,13 +2966,7 @@ qla2x00_status_entry(scsi_qla_host_t *vha, struct rsp_que *rsp, void *pkt)
 		host_to_fcp_swap(sts24->data, sizeof(sts24->data));
 		ox_id = le16_to_cpu(sts24->ox_id);
 		par_sense_len = sizeof(sts24->data);
-		/* Valid values of the retry delay timer are 0x1-0xffef */
-		if (sts24_retry_delay > 0 && sts24_retry_delay < 0xfff1) {
-			retry_delay = sts24_retry_delay & 0x3fff;
-			ql_dbg(ql_dbg_io, sp->vha, 0x3033,
-			    "%s: scope=%#x retry_delay=%#x\n", __func__,
-			    sts24_retry_delay >> 14, retry_delay);
-		}
+		sts_qual = le16_to_cpu(sts24->status_qualifier);
 	} else {
 		if (scsi_status & SS_SENSE_LEN_VALID)
 			sense_len = le16_to_cpu(sts->req_sense_length);
@@ -3012,9 +3004,9 @@ qla2x00_status_entry(scsi_qla_host_t *vha, struct rsp_que *rsp, void *pkt)
 	 * Check retry_delay_timer value if we receive a busy or
 	 * queue full.
 	 */
-	if (lscsi_status == SAM_STAT_TASK_SET_FULL ||
-	    lscsi_status == SAM_STAT_BUSY)
-		qla2x00_set_retry_delay_timestamp(fcport, retry_delay);
+	if (unlikely(lscsi_status == SAM_STAT_TASK_SET_FULL ||
+		     lscsi_status == SAM_STAT_BUSY))
+		qla2x00_set_retry_delay_timestamp(fcport, sts_qual);
 
 	/*
 	 * Based on Host and scsi status generate status code for Linux