Add interrupt support for emulator

This provides us a way to inject interrupts during a test. If a test has
interrupt_generator() defined, it will run in a separate thread. The
generator can then trigger interrupts when it decides to. The current
running task is suspended while emulator is executing ISR.

Also fixes a bug that tasks run without scheduler notifying them during
emulator start-up.

BUG=chrome-os-partner:19235
TEST=Repeatedly run all tests.
BRANCH=None

Change-Id: I0f921c47c0f848a9626da6272d9040e2b7c5ac86
Signed-off-by: Vic Yang <victoryang@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/55671

11 files changed, 302 insertions, 25 deletions

diff --git a/chip/host/uart.c b/chip/host/uart.c
index 2a05fb686e..ce8310f171 100644
--- a/chip/host/uart.c
+++ b/chip/host/uart.c
@@ -16,7 +16,7 @@
 #include "uart.h"
 #include "util.h"
 
-static int stopped;
+static int stopped = 1;
 static int int_disabled;
 static int init_done;
 
diff --git a/core/host/task.c b/core/host/task.c
index e945b603a8..23d16bd802 100644
--- a/core/host/task.c
+++ b/core/host/task.c
@@ -6,6 +6,8 @@
 /* Task scheduling / events module for Chrome EC operating system */
 
 #include <pthread.h>
+#include <semaphore.h>
+#include <signal.h>
 #include <stdint.h>
 #include <stdio.h>
 
@@ -21,6 +23,7 @@ struct emu_task_t {
 	pthread_cond_t resume;
 	uint32_t event;
 	timestamp_t wake_time;
+	uint8_t started;
 };
 
 struct task_args {
@@ -31,6 +34,17 @@ struct task_args {
 static struct emu_task_t tasks[TASK_ID_COUNT];
 static pthread_cond_t scheduler_cond;
 static pthread_mutex_t run_lock;
+static task_id_t running_task_id;
+
+static sem_t interrupt_sem;
+static pthread_mutex_t interrupt_lock;
+static pthread_t interrupt_thread;
+static int in_interrupt;
+static int interrupt_disabled;
+static void (*pending_isr)(void);
+static int generator_sleeping;
+static timestamp_t generator_sleep_deadline;
+static int has_interrupt_generator = 1;
 
 static __thread task_id_t my_task_id; /* thread local task id */
 
@@ -76,17 +90,59 @@ void task_pre_init(void)
 
 int in_interrupt_context(void)
 {
-	return 0; /* No interrupt support yet */
+	return !!in_interrupt;
 }
 
 void interrupt_disable(void)
 {
-	/* Not supported yet */
+	interrupt_disabled = 1;
 }
 
 void interrupt_enable(void)
 {
-	/* Not supported yet */
+	interrupt_disabled = 0;
+}
+
+void _task_execute_isr(int sig)
+{
+	in_interrupt = 1;
+	pending_isr();
+	sem_post(&interrupt_sem);
+	in_interrupt = 0;
+}
+
+void task_register_interrupt(void)
+{
+	sem_init(&interrupt_sem, 0, 0);
+	signal(SIGUSR1, _task_execute_isr);
+}
+
+void task_trigger_test_interrupt(void (*isr)(void))
+{
+	if (interrupt_disabled)
+		return;
+	pthread_mutex_lock(&interrupt_lock);
+
+	/* Suspend current task and excute ISR */
+	pending_isr = isr;
+	pthread_kill(tasks[running_task_id].thread, SIGUSR1);
+
+	/* Wait for ISR to complete */
+	sem_wait(&interrupt_sem);
+	while (in_interrupt)
+		;
+	pending_isr = NULL;
+
+	pthread_mutex_unlock(&interrupt_lock);
+}
+
+void interrupt_generator_udelay(unsigned us)
+{
+	generator_sleep_deadline.val = get_time().val + us;
+	generator_sleeping = 1;
+	while (get_time().val < generator_sleep_deadline.val)
+		;
+	generator_sleeping = 0;
 }
 
 uint32_t task_set_event(task_id_t tskid, uint32_t event, int wait)
@@ -101,12 +157,18 @@ uint32_t task_wait_event(int timeout_us)
 {
 	int tid = task_get_current();
 	int ret;
+	pthread_mutex_lock(&interrupt_lock);
 	if (timeout_us > 0)
 		tasks[tid].wake_time.val = get_time().val + timeout_us;
+
+	/* Transfer control to scheduler */
 	pthread_cond_signal(&scheduler_cond);
 	pthread_cond_wait(&tasks[tid].resume, &run_lock);
+
+	/* Resume */
 	ret = tasks[tid].event;
 	tasks[tid].event = 0;
+	pthread_mutex_unlock(&interrupt_lock);
 	return ret;
 }
 
@@ -148,6 +210,23 @@ task_id_t task_get_current(void)
 	return my_task_id;
 }
 
+void wait_for_task_started(void)
+{
+	int i, ok;
+
+	while (1) {
+		ok = 1;
+		for (i = 0; i < TASK_ID_COUNT - 1; ++i)
+			if (!tasks[i].started) {
+				msleep(10);
+				ok = 0;
+				break;
+			}
+		if (ok)
+			return;
+	}
+}
+
 static task_id_t task_get_next_wake(void)
 {
 	int i;
@@ -165,6 +244,42 @@ static task_id_t task_get_next_wake(void)
 	return which_task;
 }
 
+static int fast_forward(void)
+{
+	/*
+	 * No task has event pending, and thus the next time we have an
+	 * event to process must be either of:
+	 *   1. Interrupt generator triggers an interrupt
+	 *   2. The next wake alarm is reached
+	 * So we should check whether an interrupt may happen, and fast
+	 * forward to the nearest among:
+	 *   1. When interrupt generator wakes up
+	 *   2. When the next task wakes up
+	 */
+	int task_id = task_get_next_wake();
+
+	if (!has_interrupt_generator) {
+		if (task_id == TASK_ID_INVALID) {
+			return TASK_ID_IDLE;
+		} else {
+			force_time(tasks[task_id].wake_time);
+			return task_id;
+		}
+	}
+
+	if (!generator_sleeping)
+		return TASK_ID_IDLE;
+
+	if (task_id != TASK_ID_INVALID &&
+	    tasks[task_id].wake_time.val < generator_sleep_deadline.val) {
+		force_time(tasks[task_id].wake_time);
+		return task_id;
+	} else {
+		force_time(generator_sleep_deadline);
+		return TASK_ID_IDLE;
+	}
+}
+
 void task_scheduler(void)
 {
 	int i;
@@ -178,25 +293,12 @@ void task_scheduler(void)
 				break;
 			--i;
 		}
-		if (i < 0) {
-			/*
-			 * No task has event pending, and thus we are only
-			 * waiting for the next wake-up timer to fire. Let's
-			 * just find out which timer is the next and fast
-			 * forward the system time to its deadline.
-			 *
-			 * Note that once we have interrupt support, we need
-			 * to take into account the fact that an interrupt
-			 * might set an event before the next timer fires.
-			 */
-			i = task_get_next_wake();
-			if (i == TASK_ID_INVALID)
-				i = TASK_ID_IDLE;
-			else
-				force_time(tasks[i].wake_time);
-		}
+		if (i < 0)
+			i = fast_forward();
 
 		tasks[i].wake_time.val = ~0ull;
+		running_task_id = i;
+		tasks[i].started = 1;
 		pthread_cond_signal(&tasks[i].resume);
 		pthread_cond_wait(&scheduler_cond, &run_lock);
 	}
@@ -208,17 +310,39 @@ void *_task_start_impl(void *a)
 	struct task_args *arg = task_info + tid;
 	my_task_id = tid;
 	pthread_mutex_lock(&run_lock);
+
+	/* Wait for scheduler */
+	task_wait_event(1);
 	tasks[tid].event = 0;
+
+	/* Start the task routine */
 	(arg->routine)(arg->d);
+
+	/* Catch exited routine */
 	while (1)
 		task_wait_event(-1);
 }
 
+test_mockable void interrupt_generator(void)
+{
+	has_interrupt_generator = 0;
+}
+
+void *_task_int_generator_start(void *d)
+{
+	my_task_id = TASK_ID_INT_GEN;
+	interrupt_generator();
+	return NULL;
+}
+
 int task_start(void)
 {
 	int i;
 
+	task_register_interrupt();
+
 	pthread_mutex_init(&run_lock, NULL);
+	pthread_mutex_init(&interrupt_lock, NULL);
 	pthread_cond_init(&scheduler_cond, NULL);
 
 	pthread_mutex_lock(&run_lock);
@@ -226,12 +350,27 @@ int task_start(void)
 	for (i = 0; i < TASK_ID_COUNT; ++i) {
 		tasks[i].event = TASK_EVENT_WAKE;
 		tasks[i].wake_time.val = ~0ull;
+		tasks[i].started = 0;
 		pthread_cond_init(&tasks[i].resume, NULL);
 		pthread_create(&tasks[i].thread, NULL, _task_start_impl,
 			       (void *)(uintptr_t)i);
 		pthread_cond_wait(&scheduler_cond, &run_lock);
+		/*
+		 * Interrupt lock is grabbed by the task which just started.
+		 * Let's unlock it so the next task can be started.
+		 */
+		pthread_mutex_unlock(&interrupt_lock);
 	}
 
+	/*
+	 * All tasks are now waiting in task_wait_event(). Lock interrupt_lock
+	 * here so the first task chosen sees it locked.
+	 */
+	pthread_mutex_lock(&interrupt_lock);
+
+	pthread_create(&interrupt_thread, NULL,
+		       _task_int_generator_start, NULL);
+
 	task_scheduler();
 
 	return 0;
diff --git a/core/host/timer.c b/core/host/timer.c
index d945a2c4f2..dd8b88dbb4 100644
--- a/core/host/timer.c
+++ b/core/host/timer.c
@@ -10,7 +10,9 @@
 #include <time.h>
 
 #include "task.h"
+#include "test_util.h"
 #include "timer.h"
+#include "util.h"
 
 /*
  * For test that need to test for longer than 10 seconds, adjust
@@ -26,6 +28,8 @@ static int time_set;
 
 void usleep(unsigned us)
 {
+	ASSERT(!in_interrupt_context() &&
+	       task_get_current() != TASK_ID_INT_GEN);
 	task_wait_event(us);
 }
 
@@ -55,8 +59,14 @@ void force_time(timestamp_t ts)
 
 void udelay(unsigned us)
 {
-	timestamp_t deadline = get_time();
-	deadline.val += us;
+	timestamp_t deadline;
+
+	if (!in_interrupt_context() && task_get_current() == TASK_ID_INT_GEN) {
+		interrupt_generator_udelay(us);
+		return;
+	}
+
+	deadline.val = get_time().val + us;
 	while (get_time().val < deadline.val)
 		;
 }
diff --git a/include/task_id.h b/include/task_id.h
index 985c39848c..2f82e83a8b 100644
--- a/include/task_id.h
+++ b/include/task_id.h
@@ -53,7 +53,10 @@ enum {
 	/* Number of tasks */
 	TASK_ID_COUNT,
 	/* Special task identifiers */
-	TASK_ID_INVALID = 0xff  /* unable to find the task */
+#ifdef EMU_BUILD
+	TASK_ID_INT_GEN = 0xfe, /* interrupt generator */
+#endif
+	TASK_ID_INVALID = 0xff, /* unable to find the task */
 };
 #undef TASK
 
diff --git a/include/test_util.h b/include/test_util.h
index a6b110f6d1..182ad9d233 100644
--- a/include/test_util.h
+++ b/include/test_util.h
@@ -109,6 +109,28 @@ int test_get_error_count(void);
 int test_send_host_command(int command, int version, const void *params,
 			   int params_size, void *resp, int resp_size);
 
+/* Optionally defined interrupt generator entry point */
+void interrupt_generator(void);
+
+/*
+ * Trigger an interrupt. This function must only be called by interrupt
+ * generator.
+ */
+void task_trigger_test_interrupt(void (*isr)(void));
+
+/*
+ * Special implementation of udelay() for interrupt generator. Calls
+ * to udelay() from interrupt generator are delegated to this function
+ * automatically.
+ */
+void interrupt_generator_udelay(unsigned us);
+
+#ifdef EMU_BUILD
+void wait_for_task_started(void);
+#else
+static inline void wait_for_task_started(void) { }
+#endif
+
 uint32_t prng(uint32_t seed);
 
 uint32_t prng_no_seed(void);
diff --git a/test/build.mk b/test/build.mk
index 76a6a68d6f..170b0e37b0 100644
--- a/test/build.mk
+++ b/test/build.mk
@@ -22,7 +22,7 @@ test-list-$(BOARD_SAMUS)=
 test-list-host=mutex pingpong utils kb_scan kb_mkbp lid_sw power_button hooks
 test-list-host+=thermal flash queue kb_8042 extpwr_gpio console_edit system
 test-list-host+=sbs_charging adapter host_command thermal_falco led_spring
-test-list-host+=bklight_lid bklight_passthru
+test-list-host+=bklight_lid bklight_passthru interrupt
 
 adapter-y=adapter.o
 bklight_lid-y=bklight_lid.o
@@ -33,6 +33,7 @@ flash-y=flash.o
 hooks-y=hooks.o
 host_command-y=host_command.o
 kb_8042-y=kb_8042.o
+interrupt-y=interrupt.o
 kb_mkbp-y=kb_mkbp.o
 kb_scan-y=kb_scan.o
 led_spring-y=led_spring.o led_spring_impl.o
diff --git a/test/host_command.c b/test/host_command.c
index cd8d57413c..a98ee87ef6 100644
--- a/test/host_command.c
+++ b/test/host_command.c
@@ -169,6 +169,7 @@ static int test_hostcmd_invalid_checksum(void)
 
 void run_test(void)
 {
+	wait_for_task_started();
 	test_reset();
 
 	RUN_TEST(test_hostcmd_ok);
diff --git a/test/interrupt.c b/test/interrupt.c
new file mode 100644
index 0000000000..b7a42d1588
--- /dev/null
+++ b/test/interrupt.c
@@ -0,0 +1,82 @@
+/* Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ *
+ * Test interrupt support of EC emulator.
+ */
+#include <stdio.h>
+
+#include "common.h"
+#include "console.h"
+#include "test_util.h"
+#include "task.h"
+#include "timer.h"
+#include "util.h"
+
+static int main_count;
+static int has_error;
+static int interrupt_count;
+
+/* period between 50us and 3.2ms */
+#define PERIOD_US(num) (((num % 64) + 1) * 50)
+
+void my_isr(void)
+{
+	int i = main_count;
+	udelay(3 * PERIOD_US(prng_no_seed()));
+	if (i != main_count || !in_interrupt_context())
+		has_error = 1;
+	interrupt_count++;
+}
+
+void interrupt_generator(void)
+{
+	while (1) {
+		udelay(3 * PERIOD_US(prng_no_seed()));
+		task_trigger_test_interrupt(my_isr);
+	}
+}
+
+static int interrupt_test(void)
+{
+	timestamp_t deadline = get_time();
+	deadline.val += SECOND / 2;
+	while (!timestamp_expired(deadline, NULL))
+		++main_count;
+
+	ccprintf("Interrupt count: %d\n", interrupt_count);
+	ccprintf("Main thread tick: %d\n", main_count);
+
+	TEST_ASSERT(!has_error);
+	TEST_ASSERT(!in_interrupt_context());
+
+	return EC_SUCCESS;
+}
+
+static int interrupt_disable_test(void)
+{
+	timestamp_t deadline = get_time();
+	int start_int_cnt, end_int_cnt;
+	deadline.val += SECOND / 2;
+
+	interrupt_disable();
+	start_int_cnt = interrupt_count;
+	while (!timestamp_expired(deadline, NULL))
+		;
+	end_int_cnt = interrupt_count;
+	interrupt_enable();
+
+	TEST_ASSERT(start_int_cnt == end_int_cnt);
+
+	return EC_SUCCESS;
+}
+
+void run_test(void)
+{
+	test_reset();
+
+	RUN_TEST(interrupt_test);
+	RUN_TEST(interrupt_disable_test);
+
+	test_print_result();
+}
diff --git a/test/interrupt.tasklist b/test/interrupt.tasklist
new file mode 100644
index 0000000000..26cfc53453
--- /dev/null
+++ b/test/interrupt.tasklist
@@ -0,0 +1,17 @@
+/* Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+/**
+ * List of enabled tasks in the priority order
+ *
+ * The first one has the lowest priority.
+ *
+ * For each task, use the macro TASK_TEST(n, r, d, s) where :
+ * 'n' in the name of the task
+ * 'r' in the main routine of the task
+ * 'd' in an opaque parameter passed to the routine at startup
+ * 's' is the stack size in bytes; must be a multiple of 8
+ */
+#define CONFIG_TEST_TASK_LIST  /* No test task */
diff --git a/test/mutex.c b/test/mutex.c
index 10cf300e22..96bc69feee 100644
--- a/test/mutex.c
+++ b/test/mutex.c
@@ -111,5 +111,6 @@ int mutex_main_task(void *unused)
 
 void run_test(void)
 {
+	wait_for_task_started();
 	task_wake(TASK_ID_MTX1);
 }
diff --git a/test/pingpong.c b/test/pingpong.c
index c11267db74..f08a9554a7 100644
--- a/test/pingpong.c
+++ b/test/pingpong.c
@@ -61,6 +61,7 @@ int task_tick(void *data)
 
 void run_test(void)
 {
+	wait_for_task_started();
 	task_wake(TASK_ID_TICK);
 	task_wake(TASK_ID_TESTA);
 }