net: ethernet: ti: icss_iep: fix pps irq race vs pps disable

When PPS is disabled the PPS IRQ can be running and PPS timer started which
could left IEP HW in undefined, partially configured state.

Add spin_lock to protect PPS disabling vs PPS IRQ and ensure PPS timer
canceled.

Signed-off-by: Grygorii Strashko <[email protected]>
Signed-off-by: Vignesh Raghavendra <[email protected]>

drivers/net/ethernet/ti/icss_iep.c

@@ -111,6 +111,7 @@ struct icss_iep {
 	struct ptp_clock_info ptp_info;
 	struct ptp_clock *ptp_clock;
 	struct mutex ptp_clk_mutex;	/* PHC access serializer */
+	spinlock_t irq_lock; /* CMP IRQ vs icss_iep_ptp_enable access */
 	u32 def_inc;
 	s16 slow_cmp_inc;
 	u32 slow_cmp_count;
@@ -497,6 +498,7 @@ static int icss_iep_perout_enable_hw(struct icss_iep *iep,
 static int icss_iep_perout_enable(struct icss_iep *iep,
 				  struct ptp_perout_request *req, int on)
 {
+	unsigned long flags;
 	int ret = 0;
 
 	mutex_lock(&iep->ptp_clk_mutex);
@@ -509,9 +511,12 @@ static int icss_iep_perout_enable(struct icss_iep *iep,
 	if (iep->perout_enabled == !!on)
 		goto exit;
 
+	spin_lock_irqsave(&iep->irq_lock, flags);
+	hrtimer_cancel(&iep->sync_timer);
 	ret = icss_iep_perout_enable_hw(iep, req, on);
 	if (!ret)
 		iep->perout_enabled = !!on;
+	spin_unlock_irqrestore(&iep->irq_lock, flags);
 
 exit:
 	mutex_unlock(&iep->ptp_clk_mutex);
@@ -525,11 +530,18 @@ static irqreturn_t icss_iep_cap_cmp_handler(int irq, void *dev_id)
 	unsigned int val, index = 0, i, sts;
 	struct ptp_clock_event pevent;
 	irqreturn_t ret = IRQ_NONE;
+	unsigned long flags;
 	u64 ns;
 
+	spin_lock_irqsave(&iep->irq_lock, flags);
+
 	regmap_read(iep->map, ICSS_IEP_CMP_STAT_REG, &val);
 	if (val & BIT(CMP_INDEX(index))) {
 		regmap_write(iep->map, ICSS_IEP_CMP_STAT_REG, BIT(CMP_INDEX(index)));
+
+		if (!iep->pps_enabled && !iep->perout_enabled)
+			goto do_latch;
+
 		regmap_read(iep->map, ICSS_IEP_CMP1_REG0, &val);
 		ns = val;
 		if (iep->plat_data->flags & ICSS_IEP_64BIT_COUNTER_SUPPORT) {
@@ -550,9 +562,10 @@ static irqreturn_t icss_iep_cap_cmp_handler(int irq, void *dev_id)
 		ret = IRQ_HANDLED;
 	}
 
+do_latch:
 	regmap_read(iep->map, ICSS_IEP_CAPTURE_STAT_REG, &sts);
 	if (!sts)
-		return ret;
+		goto cap_cmp_exit;
 
 	for (i = 0; i < iep->ptp_info.n_ext_ts; i++) {
 		if (sts & IEP_CAP_CFG_CAPNR_1ST_EVENT_EN(i * 2)) {
@@ -571,6 +584,8 @@ static irqreturn_t icss_iep_cap_cmp_handler(int irq, void *dev_id)
 		}
 	}
 
+cap_cmp_exit:
+	spin_unlock_irqrestore(&iep->irq_lock, flags);
 	return ret;
 }
 
@@ -579,6 +594,7 @@ static int icss_iep_pps_enable(struct icss_iep *iep, int on)
 	int ret = 0;
 	struct timespec64 ts;
 	struct ptp_clock_request rq;
+	unsigned long flags;
 	u64 ns;
 
 	mutex_lock(&iep->ptp_clk_mutex);
@@ -591,6 +607,8 @@ static int icss_iep_pps_enable(struct icss_iep *iep, int on)
 	if (iep->pps_enabled == !!on)
 		goto exit;
 
+	spin_lock_irqsave(&iep->irq_lock, flags);
+
 	rq.perout.index = 0;
 	if (on) {
 		ns = icss_iep_gettime(iep);
@@ -601,12 +619,15 @@ static int icss_iep_pps_enable(struct icss_iep *iep, int on)
 		rq.perout.start.nsec = 0;
 		ret = icss_iep_perout_enable_hw(iep, &rq.perout, on);
 	} else {
+		hrtimer_cancel(&iep->sync_timer);
 		ret = icss_iep_perout_enable_hw(iep, &rq.perout, on);
 	}
 
 	if (!ret)
 		iep->pps_enabled = !!on;
 
+	spin_unlock_irqrestore(&iep->irq_lock, flags);
+
 exit:
 	mutex_unlock(&iep->ptp_clk_mutex);