PM / QoS: Initial kunit test

The pm_qos family of APIs are used in relatively difficult to reproduce
scenarios such as thermal throttling so they benefit from unit testing.

Start by adding basic tests from the the freq_qos APIs. It includes
tests for issues that were brought up on mailing lists:

https://patchwork.kernel.org/patch/11252425/#23017005
https://patchwork.kernel.org/patch/11253421/Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/base/Kconfig

@@ -148,6 +148,10 @@ config DEBUG_TEST_DRIVER_REMOVE
 	  unusable. You should say N here unless you are explicitly looking to
 	  test this functionality.
 
+config PM_QOS_KUNIT_TEST
+	bool "KUnit Test for PM QoS features"
+	depends on KUNIT
+
 config HMEM_REPORTING
 	bool
 	default n

drivers/base/power/Makefile

@@ -4,5 +4,6 @@ obj-$(CONFIG_PM_SLEEP)	+= main.o wakeup.o wakeup_stats.o
 obj-$(CONFIG_PM_TRACE_RTC)	+= trace.o
 obj-$(CONFIG_PM_GENERIC_DOMAINS)	+=  domain.o domain_governor.o
 obj-$(CONFIG_HAVE_CLK)	+= clock_ops.o
+obj-$(CONFIG_PM_QOS_KUNIT_TEST) += qos-test.o
 
 ccflags-$(CONFIG_DEBUG_DRIVER) := -DDEBUG

drivers/base/power/qos-test.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2019 NXP
+ */
+#include <kunit/test.h>
+#include <linux/pm_qos.h>
+
+/* Basic test for aggregating two "min" requests */
+static void freq_qos_test_min(struct kunit *test)
+{
+	struct freq_constraints	qos;
+	struct freq_qos_request	req1, req2;
+	int ret;
+
+	freq_constraints_init(&qos);
+	memset(&req1, 0, sizeof(req1));
+	memset(&req2, 0, sizeof(req2));
+
+	ret = freq_qos_add_request(&qos, &req1, FREQ_QOS_MIN, 1000);
+	KUNIT_EXPECT_EQ(test, ret, 1);
+	ret = freq_qos_add_request(&qos, &req2, FREQ_QOS_MIN, 2000);
+	KUNIT_EXPECT_EQ(test, ret, 1);
+
+	KUNIT_EXPECT_EQ(test, freq_qos_read_value(&qos, FREQ_QOS_MIN), 2000);
+
+	ret = freq_qos_remove_request(&req2);
+	KUNIT_EXPECT_EQ(test, ret, 1);
+	KUNIT_EXPECT_EQ(test, freq_qos_read_value(&qos, FREQ_QOS_MIN), 1000);
+
+	ret = freq_qos_remove_request(&req1);
+	KUNIT_EXPECT_EQ(test, ret, 1);
+	KUNIT_EXPECT_EQ(test, freq_qos_read_value(&qos, FREQ_QOS_MIN),
+			FREQ_QOS_MIN_DEFAULT_VALUE);
+}
+
+/* Test that requests for MAX_DEFAULT_VALUE have no effect */
+static void freq_qos_test_maxdef(struct kunit *test)
+{
+	struct freq_constraints	qos;
+	struct freq_qos_request	req1, req2;
+	int ret;
+
+	freq_constraints_init(&qos);
+	memset(&req1, 0, sizeof(req1));
+	memset(&req2, 0, sizeof(req2));
+	KUNIT_EXPECT_EQ(test, freq_qos_read_value(&qos, FREQ_QOS_MAX),
+			FREQ_QOS_MAX_DEFAULT_VALUE);
+
+	ret = freq_qos_add_request(&qos, &req1, FREQ_QOS_MAX,
+			FREQ_QOS_MAX_DEFAULT_VALUE);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+	ret = freq_qos_add_request(&qos, &req2, FREQ_QOS_MAX,
+			FREQ_QOS_MAX_DEFAULT_VALUE);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+
+	/* Add max 1000 */
+	ret = freq_qos_update_request(&req1, 1000);
+	KUNIT_EXPECT_EQ(test, ret, 1);
+	KUNIT_EXPECT_EQ(test, freq_qos_read_value(&qos, FREQ_QOS_MAX), 1000);
+
+	/* Add max 2000, no impact */
+	ret = freq_qos_update_request(&req2, 2000);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+	KUNIT_EXPECT_EQ(test, freq_qos_read_value(&qos, FREQ_QOS_MAX), 1000);
+
+	/* Remove max 1000, new max 2000 */
+	ret = freq_qos_remove_request(&req1);
+	KUNIT_EXPECT_EQ(test, ret, 1);
+	KUNIT_EXPECT_EQ(test, freq_qos_read_value(&qos, FREQ_QOS_MAX), 2000);
+}
+
+/*
+ * Test that a freq_qos_request can be added again after removal
+ *
+ * This issue was solved by commit 05ff1ba412fd ("PM: QoS: Invalidate frequency
+ * QoS requests after removal")
+ */
+static void freq_qos_test_readd(struct kunit *test)
+{
+	struct freq_constraints	qos;
+	struct freq_qos_request	req;
+	int ret;
+
+	freq_constraints_init(&qos);
+	memset(&req, 0, sizeof(req));
+	KUNIT_EXPECT_EQ(test, freq_qos_read_value(&qos, FREQ_QOS_MIN),
+			FREQ_QOS_MIN_DEFAULT_VALUE);
+
+	/* Add */
+	ret = freq_qos_add_request(&qos, &req, FREQ_QOS_MIN, 1000);
+	KUNIT_EXPECT_EQ(test, ret, 1);
+	KUNIT_EXPECT_EQ(test, freq_qos_read_value(&qos, FREQ_QOS_MIN), 1000);
+
+	/* Remove */
+	ret = freq_qos_remove_request(&req);
+	KUNIT_EXPECT_EQ(test, ret, 1);
+	KUNIT_EXPECT_EQ(test, freq_qos_read_value(&qos, FREQ_QOS_MIN),
+			FREQ_QOS_MIN_DEFAULT_VALUE);
+
+	/* Add again */
+	ret = freq_qos_add_request(&qos, &req, FREQ_QOS_MIN, 2000);
+	KUNIT_EXPECT_EQ(test, ret, 1);
+	KUNIT_EXPECT_EQ(test, freq_qos_read_value(&qos, FREQ_QOS_MIN), 2000);
+}
+
+static struct kunit_case pm_qos_test_cases[] = {
+	KUNIT_CASE(freq_qos_test_min),
+	KUNIT_CASE(freq_qos_test_maxdef),
+	KUNIT_CASE(freq_qos_test_readd),
+	{},
+};
+
+static struct kunit_suite pm_qos_test_module = {
+	.name = "qos-kunit-test",
+	.test_cases = pm_qos_test_cases,
+};
+kunit_test_suite(pm_qos_test_module);