summaryrefslogtreecommitdiff
path: root/drivers/clocksource
diff options
context:
space:
mode:
authorChen-Yu Tsai <wens@csie.org>2016-08-25 14:26:59 +0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-09-24 10:07:35 +0200
commit5fa42205ab60c43c021983e6e27301dde103e3c3 (patch)
tree6fe54ae5646c6534d38832524b0840023db7d114 /drivers/clocksource
parent8d693a2e67b5793ee58d106fded28902b7fd0f72 (diff)
clocksource/drivers/sun4i: Clear interrupts after stopping timer in probe function
commit b53e7d000d9e6e9fd2c6eb6b82d2783c67fd599e upstream. The bootloader (U-boot) sometimes uses this timer for various delays. It uses it as a ongoing counter, and does comparisons on the current counter value. The timer counter is never stopped. In some cases when the user interacts with the bootloader, or lets it idle for some time before loading Linux, the timer may expire, and an interrupt will be pending. This results in an unexpected interrupt when the timer interrupt is enabled by the kernel, at which point the event_handler isn't set yet. This results in a NULL pointer dereference exception, panic, and no way to reboot. Clear any pending interrupts after we stop the timer in the probe function to avoid this. Signed-off-by: Chen-Yu Tsai <wens@csie.org> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org> Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/clocksource')
-rw-r--r--drivers/clocksource/sun4i_timer.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/drivers/clocksource/sun4i_timer.c b/drivers/clocksource/sun4i_timer.c
index 6f3719d73390..e84877a2cacc 100644
--- a/drivers/clocksource/sun4i_timer.c
+++ b/drivers/clocksource/sun4i_timer.c
@@ -123,12 +123,16 @@ static struct clock_event_device sun4i_clockevent = {
.set_next_event = sun4i_clkevt_next_event,
};
+static void sun4i_timer_clear_interrupt(void)
+{
+ writel(TIMER_IRQ_EN(0), timer_base + TIMER_IRQ_ST_REG);
+}
static irqreturn_t sun4i_timer_interrupt(int irq, void *dev_id)
{
struct clock_event_device *evt = (struct clock_event_device *)dev_id;
- writel(0x1, timer_base + TIMER_IRQ_ST_REG);
+ sun4i_timer_clear_interrupt();
evt->event_handler(evt);
return IRQ_HANDLED;
@@ -193,6 +197,9 @@ static void __init sun4i_timer_init(struct device_node *node)
/* Make sure timer is stopped before playing with interrupts */
sun4i_clkevt_time_stop(0);
+ /* clear timer0 interrupt */
+ sun4i_timer_clear_interrupt();
+
sun4i_clockevent.cpumask = cpu_possible_mask;
sun4i_clockevent.irq = irq;