arm64: timer: Wait for the GIC to sample timer interrupt state

There is a delay between the timer asserting the interrupt and the GIC
sampling the interrupt state. Let's take that into account when we are
checking if the timer interrupt is pending (or not) at the GIC level.

An interrupt can be pending or active and pending [1,2]. Let's be precise
and check that the interrupt is actually pending, not active and pending.

[1] ARM IHI 0048B.b, section 1.4.1
[2] ARM IHI 0069E, section 1.2.2

Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
Signed-off-by: Andrew Jones <drjones@redhat.com>

2 files changed, 39 insertions, 6 deletions

diff --git a/arm/timer.c b/arm/timer.c
index b6f9dd1..ba7e8c6 100644
--- a/arm/timer.c
+++ b/arm/timer.c
@@ -8,6 +8,7 @@
 #include <libcflat.h>
 #include <devicetree.h>
 #include <errata.h>
+#include <asm/delay.h>
 #include <asm/processor.h>
 #include <asm/gic.h>
 #include <asm/io.h>
@@ -16,6 +17,14 @@
 #define ARCH_TIMER_CTL_IMASK   (1 << 1)
 #define ARCH_TIMER_CTL_ISTATUS (1 << 2)
 
+enum gic_state {
+	GIC_STATE_INACTIVE,
+	GIC_STATE_PENDING,
+	GIC_STATE_ACTIVE,
+	GIC_STATE_ACTIVE_PENDING,
+};
+
+static void *gic_isactiver;
 static void *gic_ispendr;
 static void *gic_isenabler;
 static void *gic_icenabler;
@@ -174,9 +183,28 @@ static void irq_handler(struct pt_regs *regs)
 	info->irq_received = true;
 }
 
-static bool gic_timer_pending(struct timer_info *info)
+static enum gic_state gic_timer_state(struct timer_info *info)
 {
-	return readl(gic_ispendr) & (1 << PPI(info->irq));
+	enum gic_state state = GIC_STATE_INACTIVE;
+	int i;
+	bool pending, active;
+
+	/* Wait for up to 1s for the GIC to sample the interrupt. */
+	for (i = 0; i < 10; i++) {
+		pending = readl(gic_ispendr) & (1 << PPI(info->irq));
+		active = readl(gic_isactiver) & (1 << PPI(info->irq));
+		if (!active && !pending)
+			state = GIC_STATE_INACTIVE;
+		if (pending)
+			state = GIC_STATE_PENDING;
+		if (active)
+			state = GIC_STATE_ACTIVE;
+		if (active && pending)
+			state = GIC_STATE_ACTIVE_PENDING;
+		mdelay(100);
+	}
+
+	return state;
 }
 
 static bool test_cval_10msec(struct timer_info *info)
@@ -225,15 +253,18 @@ static void test_timer(struct timer_info *info)
 	/* Enable the timer, but schedule it for much later */
 	info->write_cval(later);
 	info->write_ctl(ARCH_TIMER_CTL_ENABLE);
-	report(!gic_timer_pending(info), "not pending before");
+	report(gic_timer_state(info) == GIC_STATE_INACTIVE,
+			"not pending before");
 
 	info->write_cval(now - 1);
-	report(gic_timer_pending(info), "interrupt signal pending");
+	report(gic_timer_state(info) == GIC_STATE_PENDING,
+			"interrupt signal pending");
 
 	/* Disable the timer again and prepare to take interrupts */
 	info->write_ctl(0);
 	set_timer_irq_enabled(info, true);
-	report(!gic_timer_pending(info), "interrupt signal no longer pending");
+	report(gic_timer_state(info) == GIC_STATE_INACTIVE,
+			"interrupt signal no longer pending");
 
 	report(test_cval_10msec(info), "latency within 10 ms");
 	report(info->irq_received, "interrupt received");
@@ -307,11 +338,13 @@ static void test_init(void)
 
 	switch (gic_version()) {
 	case 2:
+		gic_isactiver = gicv2_dist_base() + GICD_ISACTIVER;
 		gic_ispendr = gicv2_dist_base() + GICD_ISPENDR;
 		gic_isenabler = gicv2_dist_base() + GICD_ISENABLER;
 		gic_icenabler = gicv2_dist_base() + GICD_ICENABLER;
 		break;
 	case 3:
+		gic_isactiver = gicv3_sgi_base() + GICD_ISACTIVER;
 		gic_ispendr = gicv3_sgi_base() + GICD_ISPENDR;
 		gic_isenabler = gicv3_sgi_base() + GICR_ISENABLER0;
 		gic_icenabler = gicv3_sgi_base() + GICR_ICENABLER0;
diff --git a/arm/unittests.cfg b/arm/unittests.cfg
index daeb5a0..1f1bb24 100644
--- a/arm/unittests.cfg
+++ b/arm/unittests.cfg
@@ -132,7 +132,7 @@ groups = psci
 [timer]
 file = timer.flat
 groups = timer
-timeout = 2s
+timeout = 8s
 arch = arm64
 
 # Exit tests