[PATCH 1/3] net: mvpp2: tai: add refcount for ptp worker

[Shmuel Hazan]

In some configurations, a single TAI can be responsible for multiple
mvpp2 interfaces. However, the mvpp2 driver will call mvpp22_tai_stop
and mvpp22_tai_start per interface RX timestamp disable/enable.

As a result, disabling timestamping for one interface would stop the
worker and corrupt the other interface's RX timestamps.

This commit solves the issue by introducing a simpler ref count for each
TAI instance.

Fixes: ce3497e2072e ("net: mvpp2: ptp: add support for receive timestamping")
Signed-off-by: Shmuel Hazan <shmuel.h@xxxxxxxxx>
---
 .../net/ethernet/marvell/mvpp2/mvpp2_tai.c    | 30 +++++++++++++++++--
 1 file changed, 28 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/marvell/mvpp2/mvpp2_tai.c b/drivers/net/ethernet/marvell/mvpp2/mvpp2_tai.c
index 95862aff49f1..9c0d50a924d9 100644
--- a/drivers/net/ethernet/marvell/mvpp2/mvpp2_tai.c
+++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2_tai.c
@@ -61,6 +61,7 @@ struct mvpp2_tai {
 	u64 period;		// nanosecond period in 32.32 fixed point
 	/* This timestamp is updated every two seconds */
 	struct timespec64 stamp;
+	u16 poll_worker_refcount;
 };
 
 static void mvpp2_tai_modify(void __iomem *reg, u32 mask, u32 set)
@@ -368,20 +369,45 @@ void mvpp22_tai_tstamp(struct mvpp2_tai *tai, u32 tstamp,
 	hwtstamp->hwtstamp = timespec64_to_ktime(ts);
 }
 
-void mvpp22_tai_start(struct mvpp2_tai *tai)
+static void mvpp22_tai_start_unlocked(struct mvpp2_tai *tai)
 {
 	long delay;
 
+	tai->poll_worker_refcount++;
+	if (tai->poll_worker_refcount > 1)
+		return;
+
 	delay = mvpp22_tai_aux_work(&tai->caps);
 
 	ptp_schedule_worker(tai->ptp_clock, delay);
 }
 
-void mvpp22_tai_stop(struct mvpp2_tai *tai)
+void mvpp22_tai_start(struct mvpp2_tai *tai)
 {
+	unsigned long flags;
+
+	spin_lock_irqsave(&tai->lock, flags);
+	mvpp22_tai_start_unlocked(tai);
+	spin_unlock_irqrestore(&tai->lock, flags);
+}
+
+static void mvpp22_tai_stop_unlocked(struct mvpp2_tai *tai)
+{
+	tai->poll_worker_refcount--;
+	if (tai->poll_worker_refcount)
+		return;
 	ptp_cancel_worker_sync(tai->ptp_clock);
 }
 
+void mvpp22_tai_stop(struct mvpp2_tai *tai)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&tai->lock, flags);
+	mvpp22_tai_stop_unlocked(tai);
+	spin_unlock_irqrestore(&tai->lock, flags);
+}
+
 static void mvpp22_tai_remove(void *priv)
 {
 	struct mvpp2_tai *tai = priv;
-- 
2.40.0