eCTS: Add nested interrupt test (Low->High)

Add a nested interrupt test to eCTS. Lower priority IRQ is fired,
followed by higher priority IRQ. Handler executions should be nested.

P1                    *-----*
                     /       \
P2             *----*         *----*
              /                     \
task_cts ----*                       *----
               A      B     C      D

BUG=chromium:653195
BRANCH=none
TEST=cts.py -m gpio, interrupt, timer; make buildall

Change-Id: I34dc7b4e819051b9070a11e69d13d6be704f2e5f
Reviewed-on: https://chromium-review.googlesource.com/408797
Commit-Ready: Daisuke Nojiri <dnojiri@chromium.org>
Tested-by: Daisuke Nojiri <dnojiri@chromium.org>
Reviewed-by: Randall Spangler <rspangler@chromium.org>

3 files changed, 81 insertions, 9 deletions

diff --git a/cts/interrupt/cts.testlist b/cts/interrupt/cts.testlist
index 6153c2b52d..01d6c1b06e 100644
--- a/cts/interrupt/cts.testlist
+++ b/cts/interrupt/cts.testlist
@@ -13,6 +13,18 @@ CTS_TEST(test_task_wait_event)
 /* Test task_disable_irq */
 CTS_TEST(test_task_disable_irq)
 
+/* Test nested interrupt. Lower priority IRQ is fired, followed by
+ * higher priority IRQ. Handler executions should be nested.
+ *
+ * P1                    *-----*
+ *                      /       \
+ * P2             *----*         *----*
+ *               /                     \
+ * task_cts ----*                       *----
+ *                A      B     C      D
+ */
+CTS_TEST(test_nested_interrupt_low_high)
+
 /*
  * Other ideas
  *
diff --git a/cts/interrupt/dut.c b/cts/interrupt/dut.c
index 43740147a7..9bf7eabde6 100644
--- a/cts/interrupt/dut.c
+++ b/cts/interrupt/dut.c
@@ -3,6 +3,7 @@
  * found in the LICENSE file.
  */
 
+#include <string.h>
 #include "common.h"
 #include "gpio.h"
 #include "registers.h"
@@ -13,6 +14,8 @@
 
 static int got_interrupt;
 static int wake_me_up;
+static int state_index;
+static char state[4];
 
 /*
  * Raw busy loop. Returns 1 if loop finishes before interrupt is triggered.
@@ -39,14 +42,35 @@ static int busy_loop(void)
 /*
  * Interrupt handler.
  */
-void cts_irq(enum gpio_signal signal)
+void cts_irq1(enum gpio_signal signal)
 {
+	state[state_index++] = 'B';
 	/* test some APIs */
 	got_interrupt = in_interrupt_context();
 
 	/* Wake up the CTS task */
 	if (wake_me_up)
 		task_wake(TASK_ID_CTS);
+	state[state_index++] = 'C';
+}
+
+void cts_irq2(enum gpio_signal signal)
+{
+	state[state_index++] = 'A';
+	busy_loop();
+	state[state_index++] = 'D';
+}
+
+static void clear_state(void)
+{
+	uint32_t *event;
+
+	got_interrupt = 0;
+	wake_me_up = 0;
+	state_index = 0;
+	memset(state, '_', sizeof(state));
+	event = task_get_event_bitmap(TASK_ID_CTS);
+	*event = 0;
 }
 
 enum cts_rc test_task_wait_event(void)
@@ -106,6 +130,27 @@ enum cts_rc test_interrupt_disable(void)
 	return CTS_RC_SUCCESS;
 }
 
+enum cts_rc test_nested_interrupt_low_high(void)
+{
+	uint32_t event;
+
+	event = task_wait_event(CTS_INTERRUPT_TRIGGER_DELAY_US * 4);
+	if (event != TASK_EVENT_TIMER) {
+		CPRINTS("Woke up by 0x%08x", event);
+		return CTS_RC_FAILURE;
+	}
+	if (!got_interrupt) {
+		CPRINTS("Interrupt context not detected");
+		return CTS_RC_TIMEOUT;
+	}
+	if (memcmp(state, "ABCD", sizeof(state))) {
+		CPRINTS("State transition differs from expectation");
+		return CTS_RC_FAILURE;
+	}
+
+	return CTS_RC_SUCCESS;
+}
+
 #include "cts_testlist.h"
 
 void cts_task(void)
@@ -113,11 +158,11 @@ void cts_task(void)
 	enum cts_rc rc;
 	int i;
 
-	gpio_enable_interrupt(GPIO_CTS_IRQ);
+	gpio_enable_interrupt(GPIO_CTS_IRQ1);
+	gpio_enable_interrupt(GPIO_CTS_IRQ2);
 	interrupt_enable();
 	for (i = 0; i < CTS_TEST_ID_COUNT; i++) {
-		got_interrupt = 0;
-		wake_me_up = 0;
+		clear_state();
 		sync();
 		rc = tests[i].run();
 		interrupt_enable();
diff --git a/cts/interrupt/th.c b/cts/interrupt/th.c
index 3bcf2168b6..87582490ed 100644
--- a/cts/interrupt/th.c
+++ b/cts/interrupt/th.c
@@ -9,34 +9,48 @@
 #include "timer.h"
 #include "watchdog.h"
 
-static void trigger_interrupt(void)
+static void trigger_interrupt1(void)
 {
 	usleep(CTS_INTERRUPT_TRIGGER_DELAY_US);
 	gpio_set_level(GPIO_OUTPUT_TEST, 0);
 	usleep(CTS_INTERRUPT_TRIGGER_DELAY_US);
 }
 
+static void trigger_interrupt2(void)
+{
+	usleep(CTS_INTERRUPT_TRIGGER_DELAY_US);
+	gpio_set_level(GPIO_CTS_IRQ2, 0);
+	usleep(CTS_INTERRUPT_TRIGGER_DELAY_US);
+}
+
 enum cts_rc test_task_wait_event(void)
 {
-	trigger_interrupt();
+	trigger_interrupt1();
 	return CTS_RC_SUCCESS;
 }
 
 enum cts_rc test_task_disable_irq(void)
 {
-	trigger_interrupt();
+	trigger_interrupt1();
 	return CTS_RC_SUCCESS;
 }
 
 enum cts_rc test_interrupt_enable(void)
 {
-	trigger_interrupt();
+	trigger_interrupt1();
 	return CTS_RC_SUCCESS;
 }
 
 enum cts_rc test_interrupt_disable(void)
 {
-	trigger_interrupt();
+	trigger_interrupt1();
+	return CTS_RC_SUCCESS;
+}
+
+enum cts_rc test_nested_interrupt_low_high(void)
+{
+	trigger_interrupt2();
+	trigger_interrupt1();
 	return CTS_RC_SUCCESS;
 }
 
@@ -51,6 +65,7 @@ void cts_task(void)
 
 	for (i = 0; i < CTS_TEST_ID_COUNT; i++) {
 		gpio_set_level(GPIO_OUTPUT_TEST, 1);
+		gpio_set_level(GPIO_CTS_IRQ2, 1);
 		sync();
 		rc = tests[i].run();
 		CPRINTF("\n%s %d\n", tests[i].name, rc);