bnxt_en: Add a non-real time mode to access NIC clock

When using a PHC that is shared between multiple hosts,
in order to achieve consistent timestamps across all hosts,
we need to isolate the PHC from any host making frequency
adjustments.

This patch adds a non-real time mode for this purpose.
The implementation is based on a free running NIC hardware timer
which is used as the timestamper time-base. Each host implements
individual adjustments to a local timecounter based on the NIC free
running timer.

Cc: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Reviewed-by: Andy Gospodarek <andrew.gospodarek@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

1 files changed, 33 insertions, 12 deletions

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt_ptp.c b/drivers/net/ethernet/broadcom/bnxt/bnxt_ptp.c
index 2132ce63193c..460cb20599f6 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt_ptp.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt_ptp.c
@@ -14,6 +14,7 @@
 #include <linux/net_tstamp.h>
 #include <linux/timekeeping.h>
 #include <linux/ptp_classify.h>
+#include <linux/clocksource.h>
 #include "bnxt_hsi.h"
 #include "bnxt.h"
 #include "bnxt_hwrm.h"
@@ -210,18 +211,37 @@ static int bnxt_ptp_adjfreq(struct ptp_clock_info *ptp_info, s32 ppb)
 						ptp_info);
 	struct hwrm_port_mac_cfg_input *req;
 	struct bnxt *bp = ptp->bp;
-	int rc;
+	int rc = 0;
 
-	rc = hwrm_req_init(bp, req, HWRM_PORT_MAC_CFG);
-	if (rc)
-		return rc;
+	if (!(ptp->bp->fw_cap & BNXT_FW_CAP_PTP_RTC)) {
+		int neg_adj = 0;
+		u32 diff;
+		u64 adj;
 
-	req->ptp_freq_adj_ppb = cpu_to_le32(ppb);
-	req->enables = cpu_to_le32(PORT_MAC_CFG_REQ_ENABLES_PTP_FREQ_ADJ_PPB);
-	rc = hwrm_req_send(ptp->bp, req);
-	if (rc)
-		netdev_err(ptp->bp->dev,
-			   "ptp adjfreq failed. rc = %d\n", rc);
+		if (ppb < 0) {
+			neg_adj = 1;
+			ppb = -ppb;
+		}
+		adj = ptp->cmult;
+		adj *= ppb;
+		diff = div_u64(adj, 1000000000ULL);
+
+		spin_lock_bh(&ptp->ptp_lock);
+		timecounter_read(&ptp->tc);
+		ptp->cc.mult = neg_adj ? ptp->cmult - diff : ptp->cmult + diff;
+		spin_unlock_bh(&ptp->ptp_lock);
+	} else {
+		rc = hwrm_req_init(bp, req, HWRM_PORT_MAC_CFG);
+		if (rc)
+			return rc;
+
+		req->ptp_freq_adj_ppb = cpu_to_le32(ppb);
+		req->enables = cpu_to_le32(PORT_MAC_CFG_REQ_ENABLES_PTP_FREQ_ADJ_PPB);
+		rc = hwrm_req_send(ptp->bp, req);
+		if (rc)
+			netdev_err(ptp->bp->dev,
+				   "ptp adjfreq failed. rc = %d\n", rc);
+	}
 	return rc;
 }
 
@@ -846,8 +866,9 @@ static void bnxt_ptp_timecounter_init(struct bnxt *bp, bool init_tc)
 		memset(&ptp->cc, 0, sizeof(ptp->cc));
 		ptp->cc.read = bnxt_cc_read;
 		ptp->cc.mask = CYCLECOUNTER_MASK(48);
-		ptp->cc.shift = 0;
-		ptp->cc.mult = 1;
+		ptp->cc.shift = BNXT_CYCLES_SHIFT;
+		ptp->cc.mult = clocksource_khz2mult(BNXT_DEVCLK_FREQ, ptp->cc.shift);
+		ptp->cmult = ptp->cc.mult;
 		ptp->next_overflow_check = jiffies + BNXT_PHC_OVERFLOW_PERIOD;
 	}
 	if (init_tc)