scsi: lpfc: Add EDC ELS support

When congestion management is enabled, issue EDC ELS to register congestion
signaling capabilities with the fabric. The response handling will process
the fabric parameters and set the reporting parameters.

Similarly, add support for receiving an EDC request from the fabric
generating a corresponding response.

Implement handlers for congestion signals from the fabric and maintain
statistics for them.

Link: https://lore.kernel.org/r/20210816162901.121235-6-jsmart2021@gmail.com
Co-developed-by: Justin Tee <justin.tee@broadcom.com>
Signed-off-by: Justin Tee <justin.tee@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

1 files changed, 633 insertions, 4 deletions

diff --git a/drivers/scsi/lpfc/lpfc_els.c b/drivers/scsi/lpfc/lpfc_els.c
index 097f132fc35b..3b1b0d3ff0d9 100644
--- a/drivers/scsi/lpfc/lpfc_els.c
+++ b/drivers/scsi/lpfc/lpfc_els.c
@@ -56,6 +56,9 @@ static int lpfc_issue_els_fdisc(struct lpfc_vport *vport,
 				struct lpfc_nodelist *ndlp, uint8_t retry);
 static int lpfc_issue_fabric_iocb(struct lpfc_hba *phba,
 				  struct lpfc_iocbq *iocb);
+static void lpfc_cmpl_els_edc(struct lpfc_hba *phba,
+			      struct lpfc_iocbq *cmdiocb,
+			      struct lpfc_iocbq *rspiocb);
 static void lpfc_cmpl_els_uvem(struct lpfc_hba *, struct lpfc_iocbq *,
 			       struct lpfc_iocbq *);
 
@@ -3286,6 +3289,9 @@ lpfc_cmpl_els_disc_cmd(struct lpfc_hba *phba, struct lpfc_iocbq *cmdiocb,
 			case ELS_CMD_SCR:
 				lpfc_issue_els_scr(vport, cmdiocb->retry);
 				break;
+			case ELS_CMD_EDC:
+				lpfc_issue_els_edc(vport, cmdiocb->retry);
+				break;
 			case ELS_CMD_RDF:
 				cmdiocb->context1 = NULL; /* save ndlp refcnt */
 				lpfc_issue_els_rdf(vport, cmdiocb->retry);
@@ -3295,6 +3301,11 @@ lpfc_cmpl_els_disc_cmd(struct lpfc_hba *phba, struct lpfc_iocbq *cmdiocb,
 		}
 		phba->fc_stat.elsRetryExceeded++;
 	}
+	if (cmd == ELS_CMD_EDC) {
+		/* must be called before checking uplStatus and returning */
+		lpfc_cmpl_els_edc(phba, cmdiocb, rspiocb);
+		return;
+	}
 	if (irsp->ulpStatus) {
 		/* ELS discovery cmd completes with error */
 		lpfc_printf_vlog(vport, KERN_WARNING, LOG_ELS,
@@ -3752,6 +3763,425 @@ lpfc_els_rcv_rdf(struct lpfc_vport *vport, struct lpfc_iocbq *cmdiocb,
 }
 
 /**
+ * lpfc_least_capable_settings - helper function for EDC rsp processing
+ * @phba: pointer to lpfc hba data structure.
+ * @pcgd: pointer to congestion detection descriptor in EDC rsp.
+ *
+ * This helper routine determines the least capable setting for
+ * congestion signals, signal freq, including scale, from the
+ * congestion detection descriptor in the EDC rsp.  The routine
+ * sets @phba values in preparation for a set_featues mailbox.
+ **/
+static void
+lpfc_least_capable_settings(struct lpfc_hba *phba,
+			    struct fc_diag_cg_sig_desc *pcgd)
+{
+	u32 rsp_sig_cap = 0, drv_sig_cap = 0;
+	u32 rsp_sig_freq_cyc = 0, rsp_sig_freq_scale = 0;
+
+	/* Get rsp signal and frequency capabilities.  */
+	rsp_sig_cap = be32_to_cpu(pcgd->xmt_signal_capability);
+	rsp_sig_freq_cyc = be16_to_cpu(pcgd->xmt_signal_frequency.count);
+	rsp_sig_freq_scale = be16_to_cpu(pcgd->xmt_signal_frequency.units);
+
+	/* If the Fport does not support signals. Set FPIN only */
+	if (rsp_sig_cap == EDC_CG_SIG_NOTSUPPORTED)
+		goto out_no_support;
+
+	/* Apply the xmt scale to the xmt cycle to get the correct frequency.
+	 * Adapter default is 100 millisSeconds.  Convert all xmt cycle values
+	 * to milliSeconds.
+	 */
+	switch (rsp_sig_freq_scale) {
+	case EDC_CG_SIGFREQ_SEC:
+		rsp_sig_freq_cyc *= MSEC_PER_SEC;
+		break;
+	case EDC_CG_SIGFREQ_MSEC:
+		rsp_sig_freq_cyc = 1;
+		break;
+	default:
+		goto out_no_support;
+	}
+
+	/* Convenient shorthand. */
+	drv_sig_cap = phba->cgn_reg_signal;
+
+	/* Choose the least capable frequency. */
+	if (rsp_sig_freq_cyc > phba->cgn_sig_freq)
+		phba->cgn_sig_freq = rsp_sig_freq_cyc;
+
+	/* Should be some common signals support. Settle on least capable
+	 * signal and adjust FPIN values. Initialize defaults to ease the
+	 * decision.
+	 */
+	phba->cgn_reg_fpin = LPFC_CGN_FPIN_WARN | LPFC_CGN_FPIN_ALARM;
+	phba->cgn_reg_signal = EDC_CG_SIG_NOTSUPPORTED;
+	if (rsp_sig_cap == EDC_CG_SIG_WARN_ONLY &&
+	    (drv_sig_cap == EDC_CG_SIG_WARN_ONLY ||
+	     drv_sig_cap == EDC_CG_SIG_WARN_ALARM)) {
+		phba->cgn_reg_signal = EDC_CG_SIG_WARN_ONLY;
+		phba->cgn_reg_fpin &= ~LPFC_CGN_FPIN_WARN;
+	}
+	if (rsp_sig_cap == EDC_CG_SIG_WARN_ALARM) {
+		if (drv_sig_cap == EDC_CG_SIG_WARN_ALARM) {
+			phba->cgn_reg_signal = EDC_CG_SIG_WARN_ALARM;
+			phba->cgn_reg_fpin = LPFC_CGN_FPIN_NONE;
+		}
+		if (drv_sig_cap == EDC_CG_SIG_WARN_ONLY) {
+			phba->cgn_reg_signal = EDC_CG_SIG_WARN_ONLY;
+			phba->cgn_reg_fpin &= ~LPFC_CGN_FPIN_WARN;
+		}
+	}
+	return;
+
+out_no_support:
+	phba->cgn_reg_signal = EDC_CG_SIG_NOTSUPPORTED;
+	phba->cgn_sig_freq = 0;
+	phba->cgn_reg_fpin = LPFC_CGN_FPIN_ALARM | LPFC_CGN_FPIN_WARN;
+}
+
+DECLARE_ENUM2STR_LOOKUP(lpfc_get_tlv_dtag_nm, fc_ls_tlv_dtag,
+			FC_LS_TLV_DTAG_INIT);
+
+/**
+ * lpfc_cmpl_els_edc - Completion callback function for EDC
+ * @phba: pointer to lpfc hba data structure.
+ * @cmdiocb: pointer to lpfc command iocb data structure.
+ * @rspiocb: pointer to lpfc response iocb data structure.
+ *
+ * This routine is the completion callback function for issuing the Exchange
+ * Diagnostic Capabilities (EDC) command. The driver issues an EDC to
+ * notify the FPort of its Congestion and Link Fault capabilities.  This
+ * routine parses the FPort's response and decides on the least common
+ * values applicable to both FPort and NPort for Warnings and Alarms that
+ * are communicated via hardware signals.
+ **/
+static void
+lpfc_cmpl_els_edc(struct lpfc_hba *phba, struct lpfc_iocbq *cmdiocb,
+		  struct lpfc_iocbq *rspiocb)
+{
+	IOCB_t *irsp;
+	struct fc_els_edc_resp *edc_rsp;
+	struct fc_tlv_desc *tlv;
+	struct fc_diag_cg_sig_desc *pcgd;
+	struct fc_diag_lnkflt_desc *plnkflt;
+	struct lpfc_dmabuf *pcmd, *prsp;
+	const char *dtag_nm;
+	u32 *pdata, dtag;
+	int desc_cnt = 0, bytes_remain;
+	bool rcv_cap_desc = false;
+	struct lpfc_nodelist *ndlp;
+
+	irsp = &rspiocb->iocb;
+	ndlp = cmdiocb->context1;
+
+	lpfc_debugfs_disc_trc(phba->pport, LPFC_DISC_TRC_ELS_CMD,
+			      "EDC cmpl:    status:x%x/x%x did:x%x",
+			      irsp->ulpStatus, irsp->un.ulpWord[4],
+			      irsp->un.elsreq64.remoteID);
+
+	/* ELS cmd tag <ulpIoTag> completes */
+	lpfc_printf_log(phba, KERN_INFO, LOG_ELS | LOG_CGN_MGMT,
+			"4201 EDC cmd tag x%x completes Data: x%x x%x x%x\n",
+			irsp->ulpIoTag, irsp->ulpStatus,
+			irsp->un.ulpWord[4], irsp->ulpTimeout);
+
+	pcmd = (struct lpfc_dmabuf *)cmdiocb->context2;
+	if (!pcmd)
+		goto out;
+
+	pdata = (u32 *)pcmd->virt;
+	if (!pdata)
+		goto out;
+
+	/* Need to clear signal values, send features MB and RDF with FPIN. */
+	if (irsp->ulpStatus)
+		goto out;
+
+	prsp = list_get_first(&pcmd->list, struct lpfc_dmabuf, list);
+	if (!prsp)
+		goto out;
+
+	edc_rsp = prsp->virt;
+	if (!edc_rsp)
+		goto out;
+
+	/* ELS cmd tag <ulpIoTag> completes */
+	lpfc_printf_log(phba, KERN_INFO, LOG_ELS | LOG_CGN_MGMT,
+			"4676 Fabric EDC Rsp: "
+			"0x%02x, 0x%08x\n",
+			edc_rsp->acc_hdr.la_cmd,
+			be32_to_cpu(edc_rsp->desc_list_len));
+
+	/*
+	 * Payload length in bytes is the response descriptor list
+	 * length minus the 12 bytes of Link Service Request
+	 * Information descriptor in the reply.
+	 */
+	bytes_remain = be32_to_cpu(edc_rsp->desc_list_len) -
+				   sizeof(struct fc_els_lsri_desc);
+	if (bytes_remain <= 0)
+		goto out;
+
+	tlv = edc_rsp->desc;
+
+	/*
+	 * cycle through EDC diagnostic descriptors to find the
+	 * congestion signaling capability descriptor
+	 */
+	while (bytes_remain) {
+		if (bytes_remain < FC_TLV_DESC_HDR_SZ) {
+			lpfc_printf_log(phba, KERN_WARNING, LOG_CGN_MGMT,
+					"6461 Truncated TLV hdr on "
+					"Diagnostic descriptor[%d]\n",
+					desc_cnt);
+			goto out;
+		}
+
+		dtag = be32_to_cpu(tlv->desc_tag);
+		switch (dtag) {
+		case ELS_DTAG_LNK_FAULT_CAP:
+			if (bytes_remain < FC_TLV_DESC_SZ_FROM_LENGTH(tlv) ||
+			    FC_TLV_DESC_SZ_FROM_LENGTH(tlv) !=
+					sizeof(struct fc_diag_lnkflt_desc)) {
+				lpfc_printf_log(
+					phba, KERN_WARNING, LOG_CGN_MGMT,
+					"6462 Truncated Link Fault Diagnostic "
+					"descriptor[%d]: %d vs 0x%zx 0x%zx\n",
+					desc_cnt, bytes_remain,
+					FC_TLV_DESC_SZ_FROM_LENGTH(tlv),
+					sizeof(struct fc_diag_cg_sig_desc));
+				goto out;
+			}
+			plnkflt = (struct fc_diag_lnkflt_desc *)tlv;
+			lpfc_printf_log(
+				phba, KERN_INFO, LOG_ELS | LOG_CGN_MGMT,
+				"4617 Link Fault Desc Data: 0x%08x 0x%08x "
+				"0x%08x 0x%08x 0x%08x\n",
+				be32_to_cpu(plnkflt->desc_tag),
+				be32_to_cpu(plnkflt->desc_len),
+				be32_to_cpu(
+					plnkflt->degrade_activate_threshold),
+				be32_to_cpu(
+					plnkflt->degrade_deactivate_threshold),
+				be32_to_cpu(plnkflt->fec_degrade_interval));
+			break;
+		case ELS_DTAG_CG_SIGNAL_CAP:
+			if (bytes_remain < FC_TLV_DESC_SZ_FROM_LENGTH(tlv) ||
+			    FC_TLV_DESC_SZ_FROM_LENGTH(tlv) !=
+					sizeof(struct fc_diag_cg_sig_desc)) {
+				lpfc_printf_log(
+					phba, KERN_WARNING, LOG_CGN_MGMT,
+					"6463 Truncated Cgn Signal Diagnostic "
+					"descriptor[%d]: %d vs 0x%zx 0x%zx\n",
+					desc_cnt, bytes_remain,
+					FC_TLV_DESC_SZ_FROM_LENGTH(tlv),
+					sizeof(struct fc_diag_cg_sig_desc));
+				goto out;
+			}
+
+			pcgd = (struct fc_diag_cg_sig_desc *)tlv;
+			lpfc_printf_log(
+				phba, KERN_INFO, LOG_ELS | LOG_CGN_MGMT,
+				"4616 CGN Desc Data: 0x%08x 0x%08x "
+				"0x%08x 0x%04x 0x%04x 0x%08x 0x%04x 0x%04x\n",
+				be32_to_cpu(pcgd->desc_tag),
+				be32_to_cpu(pcgd->desc_len),
+				be32_to_cpu(pcgd->xmt_signal_capability),
+				be32_to_cpu(pcgd->xmt_signal_frequency.count),
+				be32_to_cpu(pcgd->xmt_signal_frequency.units),
+				be32_to_cpu(pcgd->rcv_signal_capability),
+				be32_to_cpu(pcgd->rcv_signal_frequency.count),
+				be32_to_cpu(pcgd->rcv_signal_frequency.units));
+
+			/* Compare driver and Fport capabilities and choose
+			 * least common.
+			 */
+			lpfc_least_capable_settings(phba, pcgd);
+			rcv_cap_desc = true;
+			break;
+		default:
+			dtag_nm = lpfc_get_tlv_dtag_nm(dtag);
+			lpfc_printf_log(phba, KERN_WARNING, LOG_CGN_MGMT,
+					"4919 unknown Diagnostic "
+					"Descriptor[%d]: tag x%x (%s)\n",
+					desc_cnt, dtag, dtag_nm);
+		}
+
+		bytes_remain -= FC_TLV_DESC_SZ_FROM_LENGTH(tlv);
+		tlv = fc_tlv_next_desc(tlv);
+		desc_cnt++;
+	}
+
+out:
+	if (!rcv_cap_desc) {
+		phba->cgn_reg_fpin = LPFC_CGN_FPIN_ALARM | LPFC_CGN_FPIN_WARN;
+		phba->cgn_reg_signal = EDC_CG_SIG_NOTSUPPORTED;
+		phba->cgn_sig_freq = 0;
+		lpfc_printf_log(phba, KERN_WARNING, LOG_ELS | LOG_CGN_MGMT,
+				"4202 EDC rsp error - sending RDF "
+				"for FPIN only.\n");
+	}
+
+	lpfc_config_cgn_signal(phba);
+
+	/* Check to see if link went down during discovery */
+	lpfc_els_chk_latt(phba->pport);
+	lpfc_debugfs_disc_trc(phba->pport, LPFC_DISC_TRC_ELS_CMD,
+			      "EDC Cmpl:     did:x%x refcnt %d",
+			      ndlp->nlp_DID, kref_read(&ndlp->kref), 0);
+	lpfc_els_free_iocb(phba, cmdiocb);
+	lpfc_nlp_put(ndlp);
+}
+
+static void
+lpfc_format_edc_cgn_desc(struct lpfc_hba *phba, struct fc_diag_cg_sig_desc *cgd)
+{
+	/* We are assuming cgd was zero'ed before calling this routine */
+
+	/* Configure the congestion detection capability */
+	cgd->desc_tag = cpu_to_be32(ELS_DTAG_CG_SIGNAL_CAP);
+
+	/* Descriptor len doesn't include the tag or len fields. */
+	cgd->desc_len = cpu_to_be32(
+		FC_TLV_DESC_LENGTH_FROM_SZ(struct fc_diag_cg_sig_desc));
+
+	/* xmt_signal_capability already set to EDC_CG_SIG_NOTSUPPORTED.
+	 * xmt_signal_frequency.count already set to 0.
+	 * xmt_signal_frequency.units already set to 0.
+	 */
+
+	if (phba->cmf_active_mode == LPFC_CFG_OFF) {
+		/* rcv_signal_capability already set to EDC_CG_SIG_NOTSUPPORTED.
+		 * rcv_signal_frequency.count already set to 0.
+		 * rcv_signal_frequency.units already set to 0.
+		 */
+		phba->cgn_sig_freq = 0;
+		return;
+	}
+	switch (phba->cgn_reg_signal) {
+	case EDC_CG_SIG_WARN_ONLY:
+		cgd->rcv_signal_capability = cpu_to_be32(EDC_CG_SIG_WARN_ONLY);
+		break;
+	case EDC_CG_SIG_WARN_ALARM:
+		cgd->rcv_signal_capability = cpu_to_be32(EDC_CG_SIG_WARN_ALARM);
+		break;
+	default:
+		/* rcv_signal_capability left 0 thus no support */
+		break;
+	}
+
+	/* We start negotiation with lpfc_fabric_cgn_frequency, after
+	 * the completion we settle on the higher frequency.
+	 */
+	cgd->rcv_signal_frequency.count =
+		cpu_to_be16(lpfc_fabric_cgn_frequency);
+	cgd->rcv_signal_frequency.units =
+		cpu_to_be16(EDC_CG_SIGFREQ_MSEC);
+}
+
+ /**
+  * lpfc_issue_els_edc - Exchange Diagnostic Capabilities with the fabric.
+  * @vport: pointer to a host virtual N_Port data structure.
+  * @retry: retry counter for the command iocb.
+  *
+  * This routine issues an ELS EDC to the F-Port Controller to communicate
+  * this N_Port's support of hardware signals in its Congestion
+  * Capabilities Descriptor.
+  *
+  * Note: This routine does not check if one or more signals are
+  * set in the cgn_reg_signal parameter.  The caller makes the
+  * decision to enforce cgn_reg_signal as nonzero or zero depending
+  * on the conditions.  During Fabric requests, the driver
+  * requires cgn_reg_signals to be nonzero.  But a dynamic request
+  * to set the congestion mode to OFF from Monitor or Manage
+  * would correctly issue an EDC with no signals enabled to
+  * turn off switch functionality and then update the FW.
+  *
+  * Return code
+  *   0 - Successfully issued edc command
+  *   1 - Failed to issue edc command
+  **/
+int
+lpfc_issue_els_edc(struct lpfc_vport *vport, uint8_t retry)
+{
+	struct lpfc_hba  *phba = vport->phba;
+	struct lpfc_iocbq *elsiocb;
+	struct lpfc_els_edc_req *edc_req;
+	struct fc_diag_cg_sig_desc *cgn_desc;
+	u16 cmdsize;
+	struct lpfc_nodelist *ndlp;
+	u8 *pcmd = NULL;
+	u32 edc_req_size, cgn_desc_size;
+	int rc;
+
+	if (vport->port_type == LPFC_NPIV_PORT)
+		return -EACCES;
+
+	ndlp = lpfc_findnode_did(vport, Fabric_DID);
+	if (!ndlp || ndlp->nlp_state != NLP_STE_UNMAPPED_NODE)
+		return -ENODEV;
+
+	/* If HBA doesn't support signals, drop into RDF */
+	if (!phba->cgn_init_reg_signal)
+		goto try_rdf;
+
+	edc_req_size = sizeof(struct fc_els_edc);
+	cgn_desc_size = sizeof(struct fc_diag_cg_sig_desc);
+	cmdsize = edc_req_size + cgn_desc_size;
+	elsiocb = lpfc_prep_els_iocb(vport, 1, cmdsize, retry, ndlp,
+				     ndlp->nlp_DID, ELS_CMD_EDC);
+	if (!elsiocb)
+		goto try_rdf;
+
+	/* Configure the payload for the supported Diagnostics capabilities. */
+	pcmd = (u8 *)(((struct lpfc_dmabuf *)elsiocb->context2)->virt);
+	memset(pcmd, 0, cmdsize);
+	edc_req = (struct lpfc_els_edc_req *)pcmd;
+	edc_req->edc.desc_len = cpu_to_be32(cgn_desc_size);
+	edc_req->edc.edc_cmd = ELS_EDC;
+
+	cgn_desc = &edc_req->cgn_desc;
+
+	lpfc_format_edc_cgn_desc(phba, cgn_desc);
+
+	phba->cgn_sig_freq = lpfc_fabric_cgn_frequency;
+
+	lpfc_printf_vlog(vport, KERN_INFO, LOG_CGN_MGMT,
+			 "4623 Xmit EDC to remote "
+			 "NPORT x%x reg_sig x%x reg_fpin:x%x\n",
+			 ndlp->nlp_DID, phba->cgn_reg_signal,
+			 phba->cgn_reg_fpin);
+
+	elsiocb->iocb_cmpl = lpfc_cmpl_els_disc_cmd;
+	elsiocb->context1 = lpfc_nlp_get(ndlp);
+	if (!elsiocb->context1) {
+		lpfc_els_free_iocb(phba, elsiocb);
+		return -EIO;
+	}
+
+	lpfc_debugfs_disc_trc(vport, LPFC_DISC_TRC_ELS_CMD,
+			      "Issue EDC:     did:x%x refcnt %d",
+			      ndlp->nlp_DID, kref_read(&ndlp->kref), 0);
+	rc = lpfc_sli_issue_iocb(phba, LPFC_ELS_RING, elsiocb, 0);
+	if (rc == IOCB_ERROR) {
+		/* The additional lpfc_nlp_put will cause the following
+		 * lpfc_els_free_iocb routine to trigger the rlease of
+		 * the node.
+		 */
+		lpfc_els_free_iocb(phba, elsiocb);
+		lpfc_nlp_put(ndlp);
+		goto try_rdf;
+	}
+	return 0;
+try_rdf:
+	phba->cgn_reg_fpin = LPFC_CGN_FPIN_WARN | LPFC_CGN_FPIN_ALARM;
+	phba->cgn_reg_signal = EDC_CG_SIG_NOTSUPPORTED;
+	rc = lpfc_issue_els_rdf(vport, 0);
+	return rc;
+}
+
+/**
  * lpfc_cancel_retry_delay_tmo - Cancel the timer with delayed iocb-cmd retry
  * @vport: pointer to a host virtual N_Port data structure.
  * @nlp: pointer to a node-list data structure.
@@ -4515,7 +4945,7 @@ lpfc_els_free_iocb(struct lpfc_hba *phba, struct lpfc_iocbq *elsiocb)
 {
 	struct lpfc_dmabuf *buf_ptr, *buf_ptr1;
 
-	/* The I/O job is complete.  Clear the context1 data. */
+	/* The I/O iocb is complete.  Clear the context1 data. */
 	elsiocb->context1 = NULL;
 
 	/* context2  = cmd,  context2->next = rsp, context3 = bpl */
@@ -5162,6 +5592,86 @@ lpfc_els_rsp_reject(struct lpfc_vport *vport, uint32_t rejectError,
 	return 0;
 }
 
+ /**
+  * lpfc_issue_els_edc_rsp - Exchange Diagnostic Capabilities with the fabric.
+  * @vport: pointer to a host virtual N_Port data structure.
+  * @cmdiocb: pointer to the original lpfc command iocb data structure.
+  * @ndlp: NPort to where rsp is directed
+  *
+  * This routine issues an EDC ACC RSP to the F-Port Controller to communicate
+  * this N_Port's support of hardware signals in its Congestion
+  * Capabilities Descriptor.
+  *
+  * Return code
+  *   0 - Successfully issued edc rsp command
+  *   1 - Failed to issue edc rsp command
+  **/
+static int
+lpfc_issue_els_edc_rsp(struct lpfc_vport *vport, struct lpfc_iocbq *cmdiocb,
+		       struct lpfc_nodelist *ndlp)
+{
+	struct lpfc_hba  *phba = vport->phba;
+	struct lpfc_els_edc_rsp *edc_rsp;
+	struct lpfc_iocbq *elsiocb;
+	IOCB_t *icmd, *cmd;
+	uint8_t *pcmd;
+	int cmdsize, rc;
+
+	cmdsize = sizeof(struct lpfc_els_edc_rsp);
+	elsiocb = lpfc_prep_els_iocb(vport, 0, cmdsize, cmdiocb->retry,
+				     ndlp, ndlp->nlp_DID, ELS_CMD_ACC);
+	if (!elsiocb)
+		return 1;
+
+	icmd = &elsiocb->iocb;
+	cmd = &cmdiocb->iocb;
+	icmd->ulpContext = cmd->ulpContext;     /* Xri / rx_id */
+	icmd->unsli3.rcvsli3.ox_id = cmd->unsli3.rcvsli3.ox_id;
+	pcmd = (((struct lpfc_dmabuf *)elsiocb->context2)->virt);
+	memset(pcmd, 0, cmdsize);
+
+	edc_rsp = (struct lpfc_els_edc_rsp *)pcmd;
+	edc_rsp->edc_rsp.acc_hdr.la_cmd = ELS_LS_ACC;
+	edc_rsp->edc_rsp.desc_list_len = cpu_to_be32(
+		FC_TLV_DESC_LENGTH_FROM_SZ(struct lpfc_els_edc_rsp));
+	edc_rsp->edc_rsp.lsri.desc_tag = cpu_to_be32(ELS_DTAG_LS_REQ_INFO);
+	edc_rsp->edc_rsp.lsri.desc_len = cpu_to_be32(
+		FC_TLV_DESC_LENGTH_FROM_SZ(struct fc_els_lsri_desc));
+	edc_rsp->edc_rsp.lsri.rqst_w0.cmd = ELS_EDC;
+	lpfc_format_edc_cgn_desc(phba, &edc_rsp->cgn_desc);
+
+	lpfc_debugfs_disc_trc(vport, LPFC_DISC_TRC_ELS_RSP,
+			      "Issue EDC ACC:      did:x%x flg:x%x refcnt %d",
+			      ndlp->nlp_DID, ndlp->nlp_flag,
+			      kref_read(&ndlp->kref));
+	elsiocb->iocb_cmpl = lpfc_cmpl_els_rsp;
+
+	phba->fc_stat.elsXmitACC++;
+	elsiocb->context1 = lpfc_nlp_get(ndlp);
+	if (!elsiocb->context1) {
+		lpfc_els_free_iocb(phba, elsiocb);
+		return 1;
+	}
+
+	rc = lpfc_sli_issue_iocb(phba, LPFC_ELS_RING, elsiocb, 0);
+	if (rc == IOCB_ERROR) {
+		lpfc_els_free_iocb(phba, elsiocb);
+		lpfc_nlp_put(ndlp);
+		return 1;
+	}
+
+	/* Xmit ELS ACC response tag <ulpIoTag> */
+	lpfc_printf_vlog(vport, KERN_INFO, LOG_ELS,
+			 "0152 Xmit EDC ACC response Status: x%x, IoTag: x%x, "
+			 "XRI: x%x, DID: x%x, nlp_flag: x%x nlp_state: x%x "
+			 "RPI: x%x, fc_flag x%x\n",
+			 rc, elsiocb->iotag, elsiocb->sli4_xritag,
+			 ndlp->nlp_DID, ndlp->nlp_flag, ndlp->nlp_state,
+			 ndlp->nlp_rpi, vport->fc_flag);
+
+	return 0;
+}
+
 /**
  * lpfc_els_rsp_adisc_acc - Prepare and issue acc response to adisc iocb cmd
  * @vport: pointer to a virtual N_Port data structure.
@@ -8232,6 +8742,125 @@ lpfc_els_rcv_fan(struct lpfc_vport *vport, struct lpfc_iocbq *cmdiocb,
 }
 
 /**
+ * lpfc_els_rcv_edc - Process an unsolicited EDC iocb
+ * @vport: pointer to a host virtual N_Port data structure.
+ * @cmdiocb: pointer to lpfc command iocb data structure.
+ * @ndlp: pointer to a node-list data structure.
+ *
+ * Return code
+ *   0 - Successfully processed echo iocb (currently always return 0)
+ **/
+static int
+lpfc_els_rcv_edc(struct lpfc_vport *vport, struct lpfc_iocbq *cmdiocb,
+		 struct lpfc_nodelist *ndlp)
+{
+	struct lpfc_hba  *phba = vport->phba;
+	struct fc_els_edc *edc_req;
+	struct fc_tlv_desc *tlv;
+	uint8_t *payload;
+	uint32_t *ptr, dtag;
+	const char *dtag_nm;
+	int desc_cnt = 0, bytes_remain;
+	bool rcv_cap_desc = false;
+
+	payload = ((struct lpfc_dmabuf *)cmdiocb->context2)->virt;
+
+	edc_req = (struct fc_els_edc *)payload;
+	bytes_remain = be32_to_cpu(edc_req->desc_len);
+
+	ptr = (uint32_t *)payload;
+	lpfc_printf_vlog(vport, KERN_INFO, LOG_ELS | LOG_CGN_MGMT,
+			 "3319 Rcv EDC payload len %d: x%x x%x x%x\n",
+			 bytes_remain, be32_to_cpu(*ptr),
+			 be32_to_cpu(*(ptr + 1)), be32_to_cpu(*(ptr + 2)));
+
+	/* No signal support unless there is a congestion descriptor */
+	phba->cgn_reg_signal = EDC_CG_SIG_NOTSUPPORTED;
+	phba->cgn_sig_freq = 0;
+	phba->cgn_reg_fpin = LPFC_CGN_FPIN_ALARM | LPFC_CGN_FPIN_WARN;
+
+	if (bytes_remain <= 0)
+		goto out;
+
+	tlv = edc_req->desc;
+
+	/*
+	 * cycle through EDC diagnostic descriptors to find the
+	 * congestion signaling capability descriptor
+	 */
+	while (bytes_remain && !rcv_cap_desc) {
+		if (bytes_remain < FC_TLV_DESC_HDR_SZ) {
+			lpfc_printf_log(phba, KERN_WARNING, LOG_CGN_MGMT,
+					"6464 Truncated TLV hdr on "
+					"Diagnostic descriptor[%d]\n",
+					desc_cnt);
+			goto out;
+		}
+
+		dtag = be32_to_cpu(tlv->desc_tag);
+		switch (dtag) {
+		case ELS_DTAG_LNK_FAULT_CAP:
+			if (bytes_remain < FC_TLV_DESC_SZ_FROM_LENGTH(tlv) ||
+			    FC_TLV_DESC_SZ_FROM_LENGTH(tlv) !=
+				sizeof(struct fc_diag_lnkflt_desc)) {
+				lpfc_printf_log(
+					phba, KERN_WARNING, LOG_CGN_MGMT,
+					"6465 Truncated Link Fault Diagnostic "
+					"descriptor[%d]: %d vs 0x%zx 0x%zx\n",
+					desc_cnt, bytes_remain,
+					FC_TLV_DESC_SZ_FROM_LENGTH(tlv),
+					sizeof(struct fc_diag_cg_sig_desc));
+				goto out;
+			}
+			/* No action for Link Fault descriptor for now */
+			break;
+		case ELS_DTAG_CG_SIGNAL_CAP:
+			if (bytes_remain < FC_TLV_DESC_SZ_FROM_LENGTH(tlv) ||
+			    FC_TLV_DESC_SZ_FROM_LENGTH(tlv) !=
+				sizeof(struct fc_diag_cg_sig_desc)) {
+				lpfc_printf_log(
+					phba, KERN_WARNING, LOG_CGN_MGMT,
+					"6466 Truncated cgn signal Diagnostic "
+					"descriptor[%d]: %d vs 0x%zx 0x%zx\n",
+					desc_cnt, bytes_remain,
+					FC_TLV_DESC_SZ_FROM_LENGTH(tlv),
+					sizeof(struct fc_diag_cg_sig_desc));
+				goto out;
+			}
+
+			phba->cgn_reg_fpin = phba->cgn_init_reg_fpin;
+			phba->cgn_reg_signal = phba->cgn_init_reg_signal;
+
+			/* We start negotiation with lpfc_fabric_cgn_frequency.
+			 * When we process the EDC, we will settle on the
+			 * higher frequency.
+			 */
+			phba->cgn_sig_freq = lpfc_fabric_cgn_frequency;
+
+			lpfc_least_capable_settings(
+				phba, (struct fc_diag_cg_sig_desc *)tlv);
+			rcv_cap_desc = true;
+			break;
+		default:
+			dtag_nm = lpfc_get_tlv_dtag_nm(dtag);
+			lpfc_printf_log(phba, KERN_WARNING, LOG_CGN_MGMT,
+					"6467 unknown Diagnostic "
+					"Descriptor[%d]: tag x%x (%s)\n",
+					desc_cnt, dtag, dtag_nm);
+		}
+		bytes_remain -= FC_TLV_DESC_SZ_FROM_LENGTH(tlv);
+		tlv = fc_tlv_next_desc(tlv);
+		desc_cnt++;
+	}
+out:
+	/* Need to send back an ACC */
+	lpfc_issue_els_edc_rsp(vport, cmdiocb, ndlp);
+
+	lpfc_config_cgn_signal(phba);
+	return 0;
+}
+
+/**
  * lpfc_els_timeout - Handler funciton to the els timer
  * @t: timer context used to obtain the vport.
  *
@@ -8688,9 +9317,6 @@ lpfc_send_els_event(struct lpfc_vport *vport,
 }
 
 
-DECLARE_ENUM2STR_LOOKUP(lpfc_get_tlv_dtag_nm, fc_ls_tlv_dtag,
-			FC_LS_TLV_DTAG_INIT);
-
 DECLARE_ENUM2STR_LOOKUP(lpfc_get_fpin_li_event_nm, fc_fpin_li_event_types,
 			FC_FPIN_LI_EVT_TYPES_INIT);
 
@@ -9426,6 +10052,9 @@ lpfc_els_unsol_buffer(struct lpfc_hba *phba, struct lpfc_sli_ring *pring,
 
 		/* There are no replies, so no rjt codes */
 		break;
+	case ELS_CMD_EDC:
+		lpfc_els_rcv_edc(vport, elsiocb, ndlp);
+		break;
 	case ELS_CMD_RDF:
 		phba->fc_stat.elsRcvRDF++;
 		/* Accept RDF only from fabric controller */