tests: pm: policy_api: test policy behavior

Add a new test to verify the policy API behavior. Test also checks that
custom policies can be implemented.

Signed-off-by: Gerard Marull-Paretas <gerard.marull@nordicsemi.no>

tests/subsys/pm/policy_api/CMakeLists.txt

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+# Copyright (c) 2021 Nordic Semiconductor ASA.
+# SPDX-License-Identifier: Apache-2.0
+
+cmake_minimum_required(VERSION 3.20.0)
+find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
+project(policy_api)
+
+target_sources(app PRIVATE src/main.c)

tests/subsys/pm/policy_api/app.overlay

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+/*
+ * Copyright (c) 2021 Nordic Semiconductor ASA
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/ {
+	cpus {
+		cpu1: cpu@1 {
+			compatible = "zephyr,native-posix-cpu";
+			reg = <1>;
+			cpu-power-states = <&state2>;
+		};
+	};
+
+	power-states {
+		state0: state0 {
+			compatible = "zephyr,power-state";
+			power-state-name = "runtime-idle";
+			min-residency-us = <100000>;
+			exit-latency-us = <10000>;
+		};
+
+		state1: state1 {
+			compatible = "zephyr,power-state";
+			power-state-name = "suspend-to-ram";
+			min-residency-us = <1000000>;
+			exit-latency-us = <100000>;
+		};
+
+		state2: state2 {
+			compatible = "zephyr,power-state";
+			power-state-name = "suspend-to-ram";
+			min-residency-us = <500000>;
+			exit-latency-us = <50000>;
+		};
+	};
+};
+
+&cpu0 {
+	cpu-power-states = <&state0 &state1>;
+};

tests/subsys/pm/policy_api/prj.conf

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+# Copyright (c) 2021 Nordic Semiconductor ASA.
+# SPDX-License-Identifier: Apache-2.0
+
+CONFIG_ZTEST=y
+CONFIG_PM=y

tests/subsys/pm/policy_api/src/main.c

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+/*
+ * Copyright (c) 2021 Nordic Semiconductor ASA.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <pm/policy.h>
+#include <sys/time_units.h>
+#include <sys_clock.h>
+#include <ztest.h>
+
+#ifdef CONFIG_PM_POLICY_RESIDENCY
+/**
+ * @brief Test the behavior of pm_policy_next_state() when
+ * CONFIG_PM_POLICY_RESIDENCY=y.
+ */
+static void test_pm_policy_next_state_residency(void)
+{
+	const struct pm_state_info *next;
+
+	/* cpu 0 */
+	next = pm_policy_next_state(0U, 0);
+	zassert_equal(next, NULL, NULL);
+
+	next = pm_policy_next_state(0U, k_us_to_ticks_floor32(10999));
+	zassert_equal(next, NULL, NULL);
+
+	next = pm_policy_next_state(0U, k_us_to_ticks_floor32(110000));
+	zassert_equal(next->state, PM_STATE_RUNTIME_IDLE, NULL);
+	zassert_equal(next->min_residency_us, 100000, NULL);
+	zassert_equal(next->exit_latency_us, 10000, NULL);
+
+	next = pm_policy_next_state(0U, k_us_to_ticks_floor32(1099999));
+	zassert_equal(next->state, PM_STATE_RUNTIME_IDLE, NULL);
+
+	next = pm_policy_next_state(0U, k_us_to_ticks_floor32(1100000));
+	zassert_equal(next->state, PM_STATE_SUSPEND_TO_RAM, NULL);
+	zassert_equal(next->min_residency_us, 1000000, NULL);
+	zassert_equal(next->exit_latency_us, 100000, NULL);
+
+	next = pm_policy_next_state(0U, K_TICKS_FOREVER);
+	zassert_equal(next->state, PM_STATE_SUSPEND_TO_RAM, NULL);
+
+	/* cpu 1 */
+	next = pm_policy_next_state(1U, 0);
+	zassert_equal(next, NULL, NULL);
+
+	next = pm_policy_next_state(1U, k_us_to_ticks_floor32(549999));
+	zassert_equal(next, NULL, NULL);
+
+	next = pm_policy_next_state(1U, k_us_to_ticks_floor32(550000));
+	zassert_equal(next->state, PM_STATE_SUSPEND_TO_RAM, NULL);
+	zassert_equal(next->min_residency_us, 500000, NULL);
+	zassert_equal(next->exit_latency_us, 50000, NULL);
+
+	next = pm_policy_next_state(1U, K_TICKS_FOREVER);
+	zassert_equal(next->state, PM_STATE_SUSPEND_TO_RAM, NULL);
+}
+#else
+static void test_pm_policy_next_state_residency(void)
+{
+	ztest_test_skip();
+}
+#endif /* CONFIG_PM_POLICY_RESIDENCY */
+
+#ifdef CONFIG_PM_POLICY_APP
+const struct pm_state_info *pm_policy_next_state(uint8_t cpu, int32_t ticks)
+{
+	static const struct pm_state_info state = {.state = PM_STATE_SOFT_OFF};
+
+	ARG_UNUSED(cpu);
+	ARG_UNUSED(ticks);
+
+	return &state;
+}
+
+/**
+ * @brief Test that a custom policy can be implemented when
+ * CONFIG_PM_POLICY_APP=y.
+ */
+static void test_pm_policy_next_state_app(void)
+{
+	const struct pm_state_info *next;
+
+	next = pm_policy_next_state(0U, 0);
+	zassert_equal(next->state, PM_STATE_SOFT_OFF, NULL);
+}
+#else
+static void test_pm_policy_next_state_app(void)
+{
+	ztest_test_skip();
+}
+#endif /* CONFIG_PM_POLICY_APP */
+
+void test_main(void)
+{
+	ztest_test_suite(policy_api,
+			 ztest_unit_test(test_pm_policy_next_state_residency),
+			 ztest_unit_test(test_pm_policy_next_state_app));
+	ztest_run_test_suite(policy_api);
+}

tests/subsys/pm/policy_api/testcase.yaml

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+# Copyright (c) 2021 Nordic Semiconductor ASA.
+# SPDX-License-Identifier: Apache-2.0
+
+common:
+  tags: pm
+  platform_allow: native_posix native_posix_64
+tests:
+  subsys.pm.policy_api: {}
+  subsys.pm.policy_api_app:
+    extra_configs:
+      - CONFIG_PM_POLICY_APP=y