octeontx2-af: Add PTP PPS Errata workaround on CN10K silicon

Errata:
The ptp_clock_hi rollsover to zero one clock cycle before it
reaches one second boundary. As a result, the pps threshold
comparison fails after one second and the pps output signal
won't toggle further.

This patch workarounds the issue by programming the pps_lo_incr
register to 500msec minus one clock cycle period, ensuring that
the pps threshold comparison succeeds at one second rollover
boundary and pps edge toggles. After that point, the driver will
have enough time (~500msec) to reset the pps threshold value.
After each one second boundary, hrtimer is invoked which resets
the pps threshold value.
Signed-off-by: Naveen Mamindlapalli <naveenm@marvell.com>
Signed-off-by: Rakesh Babu Saladi <rsaladi2@marvell.com>
Signed-off-by: Sunil Kovvuri Goutham <sgoutham@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/marvell/octeontx2/af/mbox.h

@@ -1471,6 +1471,7 @@ enum ptp_op {
 	PTP_OP_GET_CLOCK = 1,
 	PTP_OP_GET_TSTMP = 2,
 	PTP_OP_SET_THRESH = 3,
+	PTP_OP_EXTTS_ON = 4,
 };
 
 struct ptp_req {
@@ -1478,6 +1479,7 @@ struct ptp_req {
 	u8 op;
 	s64 scaled_ppm;
 	u64 thresh;
+	int extts_on;
 };
 
 struct ptp_rsp {

drivers/net/ethernet/marvell/octeontx2/af/ptp.c

@@ -9,6 +9,8 @@
 #include <linux/device.h>
 #include <linux/module.h>
 #include <linux/pci.h>
+#include <linux/hrtimer.h>
+#include <linux/ktime.h>
 
 #include "ptp.h"
 #include "mbox.h"
@@ -77,6 +79,43 @@ static bool is_ptp_tsfmt_sec_nsec(struct ptp *ptp)
 	return false;
 }
 
+static enum hrtimer_restart ptp_reset_thresh(struct hrtimer *hrtimer)
+{
+	struct ptp *ptp = container_of(hrtimer, struct ptp, hrtimer);
+	ktime_t curr_ts = ktime_get();
+	ktime_t delta_ns, period_ns;
+	u64 ptp_clock_hi;
+
+	/* calculate the elapsed time since last restart */
+	delta_ns = ktime_to_ns(ktime_sub(curr_ts, ptp->last_ts));
+
+	/* if the ptp clock value has crossed 0.5 seconds,
+	 * its too late to update pps threshold value, so
+	 * update threshold after 1 second.
+	 */
+	ptp_clock_hi = readq(ptp->reg_base + PTP_CLOCK_HI);
+	if (ptp_clock_hi > 500000000) {
+		period_ns = ktime_set(0, (NSEC_PER_SEC + 100 - ptp_clock_hi));
+	} else {
+		writeq(500000000, ptp->reg_base + PTP_PPS_THRESH_HI);
+		period_ns = ktime_set(0, (NSEC_PER_SEC + 100 - delta_ns));
+	}
+
+	hrtimer_forward_now(hrtimer, period_ns);
+	ptp->last_ts = curr_ts;
+
+	return HRTIMER_RESTART;
+}
+
+static void ptp_hrtimer_start(struct ptp *ptp, ktime_t start_ns)
+{
+	ktime_t period_ns;
+
+	period_ns = ktime_set(0, (NSEC_PER_SEC + 100 - start_ns));
+	hrtimer_start(&ptp->hrtimer, period_ns, HRTIMER_MODE_REL);
+	ptp->last_ts = ktime_get();
+}
+
 static u64 read_ptp_tstmp_sec_nsec(struct ptp *ptp)
 {
 	u64 sec, sec1, nsec;
@@ -275,6 +314,18 @@ void ptp_start(struct ptp *ptp, u64 sclk, u32 ext_clk_freq, u32 extts)
 	/* Set 50% duty cycle for 1Hz output */
 	writeq(0x1dcd650000000000, ptp->reg_base + PTP_PPS_HI_INCR);
 	writeq(0x1dcd650000000000, ptp->reg_base + PTP_PPS_LO_INCR);
+	if (cn10k_ptp_errata(ptp)) {
+		/* The ptp_clock_hi rollsover to zero once clock cycle before it
+		 * reaches one second boundary. so, program the pps_lo_incr in
+		 * such a way that the pps threshold value comparison at one
+		 * second boundary will succeed and pps edge changes. After each
+		 * one second boundary, the hrtimer handler will be invoked and
+		 * reprograms the pps threshold value.
+		 */
+		ptp->clock_period = NSEC_PER_SEC / ptp->clock_rate;
+		writeq((0x1dcd6500ULL - ptp->clock_period) << 32,
+		       ptp->reg_base + PTP_PPS_LO_INCR);
+	}
 
 	if (cn10k_ptp_errata(ptp))
 		clock_comp = ptp_calc_adjusted_comp(ptp->clock_rate);
@@ -301,7 +352,25 @@ static int ptp_get_tstmp(struct ptp *ptp, u64 *clk)
 
 static int ptp_set_thresh(struct ptp *ptp, u64 thresh)
 {
-	writeq(thresh, ptp->reg_base + PTP_PPS_THRESH_HI);
+	if (!cn10k_ptp_errata(ptp))
+		writeq(thresh, ptp->reg_base + PTP_PPS_THRESH_HI);
+
+	return 0;
+}
+
+static int ptp_extts_on(struct ptp *ptp, int on)
+{
+	u64 ptp_clock_hi;
+
+	if (cn10k_ptp_errata(ptp)) {
+		if (on) {
+			ptp_clock_hi = readq(ptp->reg_base + PTP_CLOCK_HI);
+			ptp_hrtimer_start(ptp, (ktime_t)ptp_clock_hi);
+		} else {
+			if (hrtimer_active(&ptp->hrtimer))
+				hrtimer_cancel(&ptp->hrtimer);
+		}
+	}
 
 	return 0;
 }
@@ -341,6 +410,11 @@ static int ptp_probe(struct pci_dev *pdev,
 	else
 		ptp->read_ptp_tstmp = &read_ptp_tstmp_nsec;
 
+	if (cn10k_ptp_errata(ptp)) {
+		hrtimer_init(&ptp->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+		ptp->hrtimer.function = ptp_reset_thresh;
+	}
+
 	return 0;
 
 error_free:
@@ -365,6 +439,9 @@ static void ptp_remove(struct pci_dev *pdev)
 	struct ptp *ptp = pci_get_drvdata(pdev);
 	u64 clock_cfg;
 
+	if (cn10k_ptp_errata(ptp) && hrtimer_active(&ptp->hrtimer))
+		hrtimer_cancel(&ptp->hrtimer);
+
 	if (IS_ERR_OR_NULL(ptp))
 		return;
 
@@ -432,6 +509,9 @@ int rvu_mbox_handler_ptp_op(struct rvu *rvu, struct ptp_req *req,
 	case PTP_OP_SET_THRESH:
 		err = ptp_set_thresh(rvu->ptp, req->thresh);
 		break;
+	case PTP_OP_EXTTS_ON:
+		err = ptp_extts_on(rvu->ptp, req->extts_on);
+		break;
 	default:
 		err = -EINVAL;
 		break;

drivers/net/ethernet/marvell/octeontx2/af/ptp.h

@@ -17,7 +17,10 @@ struct ptp {
 	void __iomem *reg_base;
 	u64 (*read_ptp_tstmp)(struct ptp *ptp);
 	spinlock_t ptp_lock; /* lock */
+	struct hrtimer hrtimer;
+	ktime_t last_ts;
 	u32 clock_rate;
+	u32 clock_period;
 };
 
 struct ptp *ptp_get(void);

drivers/net/ethernet/marvell/octeontx2/nic/otx2_ptp.c

@@ -73,6 +73,23 @@ static int ptp_set_thresh(struct otx2_ptp *ptp, u64 thresh)
 	return otx2_sync_mbox_msg(&ptp->nic->mbox);
 }
 
+static int ptp_extts_on(struct otx2_ptp *ptp, int on)
+{
+	struct ptp_req *req;
+
+	if (!ptp->nic)
+		return -ENODEV;
+
+	req = otx2_mbox_alloc_msg_ptp_op(&ptp->nic->mbox);
+	if (!req)
+		return -ENOMEM;
+
+	req->op = PTP_OP_EXTTS_ON;
+	req->extts_on = on;
+
+	return otx2_sync_mbox_msg(&ptp->nic->mbox);
+}
+
 static u64 ptp_cc_read(const struct cyclecounter *cc)
 {
 	struct otx2_ptp *ptp = container_of(cc, struct otx2_ptp, cycle_counter);
@@ -189,8 +206,6 @@ static void otx2_ptp_extts_check(struct work_struct *work)
 		event.index = 0;
 		event.timestamp = timecounter_cyc2time(&ptp->time_counter, tstmp);
 		ptp_clock_event(ptp->ptp_clock, &event);
-		ptp->last_extts = tstmp;
-
 		new_thresh = tstmp % 500000000;
 		if (ptp->thresh != new_thresh) {
 			mutex_lock(&ptp->nic->mbox.lock);
@@ -198,6 +213,7 @@ static void otx2_ptp_extts_check(struct work_struct *work)
 			mutex_unlock(&ptp->nic->mbox.lock);
 			ptp->thresh = new_thresh;
 		}
+		ptp->last_extts = tstmp;
 	}
 	schedule_delayed_work(&ptp->extts_work, msecs_to_jiffies(200));
 }
@@ -235,10 +251,13 @@ static int otx2_ptp_enable(struct ptp_clock_info *ptp_info,
 				   rq->extts.index);
 		if (pin < 0)
 			return -EBUSY;
-		if (on)
+		if (on) {
+			ptp_extts_on(ptp, on);
 			schedule_delayed_work(&ptp->extts_work, msecs_to_jiffies(200));
-		else
+		} else {
+			ptp_extts_on(ptp, on);
 			cancel_delayed_work_sync(&ptp->extts_work);
+		}
 		return 0;
 	default:
 		break;