linux-kernel - [Backport for linux-5.10.y PATCH 1/2] clocksource/drivers/timer-ti-dm: Prepare to handle dra7 timer wrap issue

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Message-Id: <20210517082244.17447-1-tony@atomide.com>
Date:   Mon, 17 May 2021 11:22:43 +0300
From:   Tony Lindgren <tony@...mide.com>
To:     stable@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, linux-omap@...r.kernel.org,
        Daniel Lezcano <daniel.lezcano@...aro.org>
Subject: [Backport for linux-5.10.y PATCH 1/2] clocksource/drivers/timer-ti-dm: Prepare to handle dra7 timer wrap issue

Upstream commit 3efe7a878a11c13b5297057bfc1e5639ce1241ce. Updated to
apply to stable linux-5.10.y without need for upstream typo fix commit
4bf07f6562a01a488877e05267808da7147f44a5. Needed to avoid duplicate
code for upstream commit 25de4ce5ed02994aea8bc111d133308f6fd62566.

There is a timer wrap issue on dra7 for the ARM architected timer.
In a typical clock configuration the timer fails to wrap after 388 days.

To work around the issue, we need to use timer-ti-dm timers instead.

Let's prepare for adding support for percpu timers by adding a common
dmtimer_clkevt_init_common() and call it from dmtimer_clockevent_init().
This patch makes no intentional functional changes.

Signed-off-by: Tony Lindgren <tony@...mide.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@...aro.org>
Link: https://lore.kernel.org/r/20210323074326.28302-2-tony@atomide.com
---
 drivers/clocksource/timer-ti-dm-systimer.c | 68 ++++++++++++++--------
 1 file changed, 44 insertions(+), 24 deletions(-)

diff --git a/drivers/clocksource/timer-ti-dm-systimer.c b/drivers/clocksource/timer-ti-dm-systimer.c
--- a/drivers/clocksource/timer-ti-dm-systimer.c
+++ b/drivers/clocksource/timer-ti-dm-systimer.c
@@ -530,17 +530,17 @@ static void omap_clockevent_unidle(struct clock_event_device *evt)
 	writel_relaxed(OMAP_TIMER_INT_OVERFLOW, t->base + t->wakeup);
 }
 
-static int __init dmtimer_clockevent_init(struct device_node *np)
+static int __init dmtimer_clkevt_init_common(struct dmtimer_clockevent *clkevt,
+					     struct device_node *np,
+					     unsigned int features,
+					     const struct cpumask *cpumask,
+					     const char *name,
+					     int rating)
 {
-	struct dmtimer_clockevent *clkevt;
 	struct clock_event_device *dev;
 	struct dmtimer_systimer *t;
 	int error;
 
-	clkevt = kzalloc(sizeof(*clkevt), GFP_KERNEL);
-	if (!clkevt)
-		return -ENOMEM;
-
 	t = &clkevt->t;
 	dev = &clkevt->dev;
 
@@ -548,25 +548,23 @@ static int __init dmtimer_clockevent_init(struct device_node *np)
 	 * We mostly use cpuidle_coupled with ARM local timers for runtime,
 	 * so there's probably no use for CLOCK_EVT_FEAT_DYNIRQ here.
 	 */
-	dev->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
-	dev->rating = 300;
+	dev->features = features;
+	dev->rating = rating;
 	dev->set_next_event = dmtimer_set_next_event;
 	dev->set_state_shutdown = dmtimer_clockevent_shutdown;
 	dev->set_state_periodic = dmtimer_set_periodic;
 	dev->set_state_oneshot = dmtimer_clockevent_shutdown;
 	dev->set_state_oneshot_stopped = dmtimer_clockevent_shutdown;
 	dev->tick_resume = dmtimer_clockevent_shutdown;
-	dev->cpumask = cpu_possible_mask;
+	dev->cpumask = cpumask;
 
 	dev->irq = irq_of_parse_and_map(np, 0);
-	if (!dev->irq) {
-		error = -ENXIO;
-		goto err_out_free;
-	}
+	if (!dev->irq)
+		return -ENXIO;
 
 	error = dmtimer_systimer_setup(np, &clkevt->t);
 	if (error)
-		goto err_out_free;
+		return error;
 
 	clkevt->period = 0xffffffff - DIV_ROUND_CLOSEST(t->rate, HZ);
 
@@ -578,32 +576,54 @@ static int __init dmtimer_clockevent_init(struct device_node *np)
 	writel_relaxed(OMAP_TIMER_CTRL_POSTED, t->base + t->ifctrl);
 
 	error = request_irq(dev->irq, dmtimer_clockevent_interrupt,
-			    IRQF_TIMER, "clockevent", clkevt);
+			    IRQF_TIMER, name, clkevt);
 	if (error)
 		goto err_out_unmap;
 
 	writel_relaxed(OMAP_TIMER_INT_OVERFLOW, t->base + t->irq_ena);
 	writel_relaxed(OMAP_TIMER_INT_OVERFLOW, t->base + t->wakeup);
 
-	pr_info("TI gptimer clockevent: %s%lu Hz at %pOF\n",
-		of_find_property(np, "ti,timer-alwon", NULL) ?
+	pr_info("TI gptimer %s: %s%lu Hz at %pOF\n",
+		name, of_find_property(np, "ti,timer-alwon", NULL) ?
 		"always-on " : "", t->rate, np->parent);
 
-	clockevents_config_and_register(dev, t->rate,
-					3, /* Timer internal resynch latency */
+	return 0;
+
+err_out_unmap:
+	iounmap(t->base);
+
+	return error;
+}
+
+static int __init dmtimer_clockevent_init(struct device_node *np)
+{
+	struct dmtimer_clockevent *clkevt;
+	int error;
+
+	clkevt = kzalloc(sizeof(*clkevt), GFP_KERNEL);
+	if (!clkevt)
+		return -ENOMEM;
+
+	error = dmtimer_clkevt_init_common(clkevt, np,
+					   CLOCK_EVT_FEAT_PERIODIC |
+					   CLOCK_EVT_FEAT_ONESHOT,
+					   cpu_possible_mask, "clockevent",
+					   300);
+	if (error)
+		goto err_out_free;
+
+	clockevents_config_and_register(&clkevt->dev, clkevt->t.rate,
+					3, /* Timer internal resync latency */
 					0xffffffff);
 
 	if (of_machine_is_compatible("ti,am33xx") ||
 	    of_machine_is_compatible("ti,am43")) {
-		dev->suspend = omap_clockevent_idle;
-		dev->resume = omap_clockevent_unidle;
+		clkevt->dev.suspend = omap_clockevent_idle;
+		clkevt->dev.resume = omap_clockevent_unidle;
 	}
 
 	return 0;
 
-err_out_unmap:
-	iounmap(t->base);
-
 err_out_free:
 	kfree(clkevt);
 
-- 
2.31.1