mutex: add unit testing

Exercise all basic use cases on mutexes.

Signed-off-by: Vincent Palatin <vpalatin@chromium.org>

BUG=None
TEST=make qemu-tests

Change-Id: I40de3ae59862db96b40a067c9ad54a978f5646b8

1 files changed, 112 insertions, 0 deletions

diff --git a/test/mutex.c b/test/mutex.c
new file mode 100644
index 0000000000..a5b7244e36
--- /dev/null
+++ b/test/mutex.c
@@ -0,0 +1,112 @@
+/* Copyright (c) 2011 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.
+ * Copyright 2011 Google Inc.
+ *
+ * Tasks for mutexes basic tests.
+ */
+
+#include "common.h"
+#include "uart.h"
+#include "task.h"
+#include "timer.h"
+
+static struct mutex mtx;
+
+/* Linear congruential pseudo random number generator*/
+static uint32_t prng(uint32_t x)
+{
+	return 22695477 * x + 1;
+}
+
+/* period between 50us and 12.8ms */
+#define PERIOD_US(num) (((num % 256) + 1) * 50)
+/* one of the 3 MTX3x tasks */
+#define RANDOM_TASK(num) (TASK_ID_MTX3C + (num % 3))
+
+int mutex_random_task(void *unused)
+{
+	char letter = 'A'+(TASK_ID_MTX3A - task_get_current());
+	/* wait to be activated */
+
+	while (1) {
+		task_wait_msg(0);
+		uart_printf("%c+\n", letter);
+		mutex_lock(&mtx);
+		uart_printf("%c=\n", letter);
+		task_wait_msg(0);
+		uart_printf("%c-\n", letter);
+		mutex_unlock(&mtx);
+	}
+
+	task_wait_msg(0);
+
+	return EC_SUCCESS;
+}
+
+int mutex_second_task(void *unused)
+{
+	task_id_t id = task_get_current();
+
+	uart_printf("\n[Mutex second task %d]\n", id);
+
+	task_wait_msg(0);
+	uart_printf("MTX2: locking...");
+	mutex_lock(&mtx);
+	uart_printf("done\n");
+	task_send_msg(TASK_ID_MTX1, 1, 0);
+	uart_printf("MTX2: unlocking...\n");
+	mutex_unlock(&mtx);
+
+	task_wait_msg(0);
+
+	return EC_SUCCESS;
+}
+
+int mutex_main_task(void *unused)
+{
+	task_id_t id = task_get_current();
+	uint32_t rdelay = (uint32_t)0x0bad1dea;
+	uint32_t rtask = (uint32_t)0x1a4e1dea;
+	int i;
+
+	uart_printf("\n[Mutex main task %d]\n", id);
+
+	/* --- Lock/Unlock without contention --- */
+	uart_printf("No contention :");
+	mutex_lock(&mtx);
+	mutex_unlock(&mtx);
+	mutex_lock(&mtx);
+	mutex_unlock(&mtx);
+	mutex_lock(&mtx);
+	mutex_unlock(&mtx);
+	uart_printf("done.\n");
+
+	/* --- Serialization to test simple contention --- */
+	uart_printf("Simple contention :\n");
+	/* lock the mutex from the other task */
+	task_send_msg(TASK_ID_MTX2, 1, 1);
+	/* block on the mutex */
+	uart_printf("MTX1: blocking...\n");
+	mutex_lock(&mtx);
+	uart_printf("MTX1: get lock\n");
+	mutex_unlock(&mtx);
+
+	/* --- mass lock-unlocking from several tasks --- */
+	uart_printf("Massive locking/unlocking :\n");
+	for (i = 0; i < 500; i++) {
+		/* Wake up a random task */
+		task_send_msg(RANDOM_TASK(rtask), 1, 0);
+		/* next pseudo random delay */
+		rtask = prng(rtask);
+		/* Wait for a "random" period */
+		task_wait_msg(PERIOD_US(rdelay));
+		/* next pseudo random delay */
+		rdelay = prng(rdelay);
+	}
+
+	uart_printf("Test done.\n");
+	task_wait_msg(0);
+
+	return EC_SUCCESS;
+}