tests: drivers: clock_control: Add initial DVFS polling

Add a setup routine that waits until DVFS finishes its initialization
and during that time tries to constantly make requests that involve
DVFS. This polling ensures that the clock control driver can properly
recover after an unsuccessful request.

Signed-off-by: Andrzej Głąbek <andrzej.glabek@nordicsemi.no>

Author: anangl

tests/drivers/clock_control/nrf_clock_control/src/main.c

@@ -215,8 +215,6 @@ static void test_clock_control_request(const struct test_clk_context *clk_contex
 ZTEST(nrf2_clock_control, test_cpuapp_hsfll_control)
 {
 	TC_PRINT("APPLICATION DOMAIN HSFLL test\n");
-	/* Wait for the DVFS init to complete */
-	k_msleep(3000);
 	test_clock_control_request(cpuapp_hsfll_test_clk_contexts,
 				   ARRAY_SIZE(cpuapp_hsfll_test_clk_contexts));
 }
@@ -311,4 +309,56 @@ ZTEST(nrf2_clock_control, test_safe_request_cancellation)
 	zassert_between_inclusive(ret, ONOFF_STATE_ON, ONOFF_STATE_TO_ON);
 }
 
-ZTEST_SUITE(nrf2_clock_control, NULL, NULL, NULL, NULL, NULL);
+static void *setup(void)
+{
+#if defined(CONFIG_BOARD_NRF54H20DK_NRF54H20_CPUAPP)
+	const struct device *clk_dev = DEVICE_DT_GET(DT_NODELABEL(cpuapp_hsfll));
+	const struct nrf_clock_spec clk_spec = {
+		.frequency = MHZ(64),
+	};
+	struct onoff_client cli;
+	uint32_t start_uptime;
+	const uint32_t timeout_ms = 3000;
+
+	zassert_true(device_is_ready(clk_dev),
+		     "%s is not ready", clk_dev->name);
+
+	/* Constantly make requests to DVFS until one is successful (what also
+	 * means that the service has finished its initialization). This loop
+	 * also verifies that the clock control driver is able to recover after
+	 * an unsuccesful attempt to start a clock (at least one initial request
+	 * is expected to fail here due to DFVS not being initialized yet).
+	 */
+	TC_PRINT("Polling DVFS until it is ready\n");
+	start_uptime = k_uptime_get_32();
+	while (1) {
+		int status;
+		int ret;
+
+		sys_notify_init_spinwait(&cli.notify);
+		ret = nrf_clock_control_request(clk_dev, &clk_spec, &cli);
+		/* The on-off manager for this clock controller is expected to
+		 * always be in the off state when a request is done (its error
+		 * state is expected to be cleared by the clock control driver).
+		 */
+		zassert_equal(ret, ONOFF_STATE_OFF, "request result: %d", ret);
+		do {
+			ret = sys_notify_fetch_result(&cli.notify, &status);
+			k_yield();
+		} while (ret == -EAGAIN);
+
+		if (status == 0) {
+			TC_PRINT("DVFS is ready\n");
+			break;
+		} else if ((k_uptime_get_32() - start_uptime) >= timeout_ms) {
+			TC_PRINT("DVFS is not ready after %u ms\n", timeout_ms);
+			ztest_test_fail();
+			break;
+		}
+	}
+#endif
+
+	return NULL;
+}
+
+ZTEST_SUITE(nrf2_clock_control, NULL, setup, NULL, NULL, NULL);