linux-kernel - [PATCH net v3] net: ti: icssg-prueth: Fix 1 PPS sync

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Message-ID: <20241028111051.1546143-1-m-malladi@ti.com>
Date: Mon, 28 Oct 2024 16:40:52 +0530
From: Meghana Malladi <m-malladi@...com>
To: <vigneshr@...com>, <grygorii.strashko@...com>, <horms@...nel.org>,
        <jan.kiszka@...mens.com>, <diogo.ivo@...mens.com>, <pabeni@...hat.com>,
        <kuba@...nel.org>, <edumazet@...gle.com>, <davem@...emloft.net>,
        <andrew+netdev@...n.ch>
CC: <linux-kernel@...r.kernel.org>, <netdev@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>, <srk@...com>,
        Roger Quadros
	<rogerq@...nel.org>, <danishanwar@...com>,
        <m-malladi@...com>, "Vadim
 Fedorenko" <vadim.fedorenko@...ux.dev>
Subject: [PATCH net v3] net: ti: icssg-prueth: Fix 1 PPS sync

The first PPS latch time needs to be calculated by the driver
(in rounded off seconds) and configured as the start time
offset for the cycle. After synchronizing two PTP clocks
running as master/slave, missing this would cause master
and slave to start immediately with some milliseconds
drift which causes the PPS signal to never synchronize with
the PTP master.

Fixes: 186734c15886 ("net: ti: icssg-prueth: add packet timestamping and ptp support")
Signed-off-by: Meghana Malladi <m-malladi@...com>
Reviewed-by: Vadim Fedorenko <vadim.fedorenko@...ux.dev>
Reviewed-by: MD Danish Anwar <danishanwar@...com>
---

Hello,

This patch is based on net-next tagged next-2024102.
v2:https://lore.kernel.org/all/20241024113140.973928-1-m-malladi@ti.com/
Changes since v2 (v3-v2):
- Use hi_lo_writeq() and hi_lo_readq() instead of own helpers
(icssg_readq() & iccsg_writeq()) as asked by Andrew Lunn <andrew@...n.ch>
- Collected Reviewed-by tags from Vadim and Danish

Regards,
Meghana.

 drivers/net/ethernet/ti/icssg/icssg_prueth.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/ti/icssg/icssg_prueth.c b/drivers/net/ethernet/ti/icssg/icssg_prueth.c
index 0556910938fa..678a99882627 100644
--- a/drivers/net/ethernet/ti/icssg/icssg_prueth.c
+++ b/drivers/net/ethernet/ti/icssg/icssg_prueth.c
@@ -16,6 +16,7 @@
 #include <linux/if_hsr.h>
 #include <linux/if_vlan.h>
 #include <linux/interrupt.h>
+#include <linux/io-64-nonatomic-hi-lo.h>
 #include <linux/kernel.h>
 #include <linux/mfd/syscon.h>
 #include <linux/module.h>
@@ -411,6 +412,8 @@ static int prueth_perout_enable(void *clockops_data,
 	struct prueth_emac *emac = clockops_data;
 	u32 reduction_factor = 0, offset = 0;
 	struct timespec64 ts;
+	u64 current_cycle;
+	u64 start_offset;
 	u64 ns_period;
 
 	if (!on)
@@ -449,8 +452,14 @@ static int prueth_perout_enable(void *clockops_data,
 	writel(reduction_factor, emac->prueth->shram.va +
 		TIMESYNC_FW_WC_SYNCOUT_REDUCTION_FACTOR_OFFSET);
 
-	writel(0, emac->prueth->shram.va +
-		TIMESYNC_FW_WC_SYNCOUT_START_TIME_CYCLECOUNT_OFFSET);
+	current_cycle = hi_lo_readq(emac->prueth->shram.va +
+				    TIMESYNC_FW_WC_CYCLECOUNT_OFFSET);
+
+	/* Rounding of current_cycle count to next second */
+	start_offset = roundup(current_cycle, MSEC_PER_SEC);
+
+	hi_lo_writeq(start_offset, emac->prueth->shram.va +
+		     TIMESYNC_FW_WC_SYNCOUT_START_TIME_CYCLECOUNT_OFFSET);
 
 	return 0;
 }

base-commit: 73840ca5ef361f143b89edd5368a1aa8c2979241
-- 
2.25.1