[PATCH 1/3 v2] clocksource/drivers/fttmr010: Be stricter on IRQs

[Linus Walleij]

Make sure we check that the right interrupt occurred before
calling the event handler for timer 1. Report spurious IRQs
as IRQ_NONE.

Cc: Cédric Le Goater <clg@xxxxxxxx>
Cc: Joel Stanley <joel@xxxxxxxxx>
Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
---
ChangeLog v1->v2:
- Do not try to detect spurious IRQs on the Aspeed
  2400 and 2500 that miss the IRQ status register.
---
 drivers/clocksource/timer-fttmr010.c | 42 ++++++++++++++++++++++------
 1 file changed, 34 insertions(+), 8 deletions(-)

diff --git a/drivers/clocksource/timer-fttmr010.c b/drivers/clocksource/timer-fttmr010.c
index 126fb1f259b2..f47099dda96b 100644
--- a/drivers/clocksource/timer-fttmr010.c
+++ b/drivers/clocksource/timer-fttmr010.c
@@ -253,20 +253,46 @@ static int fttmr010_timer_set_periodic(struct clock_event_device *evt)
  */
 static irqreturn_t fttmr010_timer_interrupt(int irq, void *dev_id)
 {
-	struct clock_event_device *evt = dev_id;
+	struct fttmr010 *fttmr010 = dev_id;
+	struct clock_event_device *evt = &fttmr010->clkevt;
+	u32 val;
+
+	if (fttmr010->is_aspeed) {
+		/*
+		 * Aspeed versions do not implement the interrupt
+		 * status register and cannot detect spurious
+		 * interrupts.
+		 */
+		evt->event_handler(evt);
+		return IRQ_HANDLED;
+	}
+
+	val = readl(fttmr010->base + TIMER_INTR_STATE);
+	if (val & (TIMER_1_INT_MATCH1 | TIMER_1_INT_OVERFLOW))
+		evt->event_handler(evt);
+	else
+		/* Spurious IRQ */
+		return IRQ_NONE;
 
-	evt->event_handler(evt);
 	return IRQ_HANDLED;
 }
 
 static irqreturn_t ast2600_timer_interrupt(int irq, void *dev_id)
 {
-	struct clock_event_device *evt = dev_id;
-	struct fttmr010 *fttmr010 = to_fttmr010(evt);
+	struct fttmr010 *fttmr010 = dev_id;
+	struct clock_event_device *evt = &fttmr010->clkevt;
+	u32 val;
 
-	writel(0x1, fttmr010->base + TIMER_INTR_STATE);
+	val = readl(fttmr010->base + TIMER_INTR_STATE);
+	if (val & (TIMER_1_INT_MATCH1 | TIMER_1_INT_OVERFLOW)) {
+		writel(TIMER_1_INT_MATCH1, fttmr010->base + TIMER_INTR_STATE);
+		evt->event_handler(evt);
+	} else {
+		/* Just clear any spurious IRQs from the block */
+		writel(val, fttmr010->base + TIMER_INTR_STATE);
+		return IRQ_NONE;
+	}
 
-	evt->event_handler(evt);
 	return IRQ_HANDLED;
 }
 
@@ -384,12 +410,12 @@ static int __init fttmr010_common_init(struct device_node *np,
 		fttmr010->timer_shutdown = ast2600_timer_shutdown;
 		ret = request_irq(irq, ast2600_timer_interrupt,
 				  IRQF_TIMER, "FTTMR010-TIMER1",
-				  &fttmr010->clkevt);
+				  fttmr010);
 	} else {
 		fttmr010->timer_shutdown = fttmr010_timer_shutdown;
 		ret = request_irq(irq, fttmr010_timer_interrupt,
 				  IRQF_TIMER, "FTTMR010-TIMER1",
-				  &fttmr010->clkevt);
+				  fttmr010);
 	}
 	if (ret) {
 		pr_err("FTTMR010-TIMER1 no IRQ\n");
-- 
2.31.1