tests: driver: nrf_clock_control: Verify that clocks are ready

Ensure that a given clock controller is ready before making requests
to it. Otherwise, if for some reason the clock controller fails to
initialize (for example, when BICR turns out to be not populated with
required values), the test may end up with an enigmatic bus fault.

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

Author: anangl

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

@@ -199,6 +199,9 @@ static void test_clock_control_request(const struct test_clk_context *clk_contex
 			clk_dev = clk_context->clk_dev;
 			clk_spec = &clk_context->clk_specs[u];
 
+			zassert_true(device_is_ready(clk_dev),
+				     "%s is not ready", clk_dev->name);
+
 			TC_PRINT("Applying clock (%s) spec: frequency %d, accuracy %d, precision "
 				 "%d\n",
 				 clk_dev->name, clk_spec->frequency, clk_spec->accuracy,
@@ -211,7 +214,6 @@ static void test_clock_control_request(const struct test_clk_context *clk_contex
 #if CONFIG_BOARD_NRF54H20DK_NRF54H20_CPUAPP
 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);
@@ -245,6 +247,9 @@ ZTEST(nrf2_clock_control, test_invalid_fll16m_clock_spec_response)
 			clk_dev = clk_context->clk_dev;
 			clk_spec = &clk_context->clk_specs[u];
 
+			zassert_true(device_is_ready(clk_dev),
+				     "%s is not ready", clk_dev->name);
+
 			TC_PRINT("Applying clock (%s) spec: frequency %d, accuracy %d, precision "
 				 "%d\n",
 				 clk_dev->name, clk_spec->frequency, clk_spec->accuracy,
@@ -290,6 +295,9 @@ ZTEST(nrf2_clock_control, test_safe_request_cancellation)
 	const struct device *clk_dev = clk_context->clk_dev;
 	const struct nrf_clock_spec *clk_spec = &test_clk_specs_lfclk[0];
 
+	zassert_true(device_is_ready(clk_dev),
+		     "%s is not ready", clk_dev->name);
+
 	TC_PRINT("Safe clock request cancellation\n");
 	TC_PRINT("Clock under test: %s\n", clk_dev->name);
 	sys_notify_init_spinwait(&cli.notify);