mpsl: Use nrf2 cloc ctrl resolve API to get LFCLK accuracy

When MPSL uses nrf2 clock control e.g. on nRF54h20, is should
call nrf_clock_control_resolve to get information about the
LFCLK source accuracy. The LFCLK souce is unknown to the MPSL
so it asks for the worst alowed LFCLK accuracy, which is 500PPM.
The API should provide the most accurate and the most power
efficient clock source.

Signed-off-by: Piotr Pryga <[email protected]>

Author: ppryga-nordic

subsys/mpsl/clock_ctrl/mpsl_clock_ctrl.c

@@ -293,20 +293,15 @@ static int32_t m_lfclk_release(void)
 
 #elif defined(CONFIG_CLOCK_CONTROL_NRF2)
 
-/* Temporary macro because there is no system level configuration of LFCLK source and its accuracy
- * for nRF54H SoC series. What more, there is no API to retrieve the information about accuracy of
- * available LFCLK.
+/* Minimum accuracy of LFCLK that is required by Bluetooth Core Specification Version 6.1, Vol 6,
+ * Part B, Section 4.2.2.
  */
 #define MPSL_LFCLK_ACCURACY_PPM 500
-
-static const struct nrf_clock_spec m_lfclk_specs = {
-	.frequency = 32768,
-	.accuracy = MPSL_LFCLK_ACCURACY_PPM,
-	/* This affects selected LFCLK source. It doesn't switch to higher accuracy but selects more
-	 * precise but current hungry lfclk source.
-	 */
-	.precision = NRF_CLOCK_CONTROL_PRECISION_DEFAULT,
-};
+/* The variable holds actual LFCLK specification that is use in the system.
+ * Enabled LFCLK at least matches the minimum Bluetooth sleep clock accuracy,
+ * but it might be better.
+ */
+static struct nrf_clock_spec m_lfclk_specs;
 
 #define HFCLK_LABEL DT_NODELABEL(hfxo)
 
@@ -515,6 +510,33 @@ static mpsl_clock_hfclk_ctrl_source_t m_nrf_hfclk_ctrl_data = {
 	.hfclk_is_running = m_hfclk_is_running,
 };
 
+#if defined(CONFIG_CLOCK_CONTROL_NRF2)
+static int m_lfclk_accuracy_get(void)
+{
+	int err;
+	static const struct nrf_clock_spec lfclk_specs_req = {
+		/* LFCLK frequency [Hz] */
+		.frequency = 32768,
+		.accuracy = MPSL_LFCLK_ACCURACY_PPM,
+		/* This affects selected LFCLK source. It doesn't switch to higher accuracy
+		 * but selects more precise but current hungry lfclk source.
+		 */
+		.precision = NRF_CLOCK_CONTROL_PRECISION_DEFAULT,
+	};
+
+	err = nrf_clock_control_resolve(DEVICE_DT_GET(DT_NODELABEL(lfclk)), &lfclk_specs_req,
+					&m_lfclk_specs);
+	if (err < 0) {
+		LOG_ERR("Failed to resolve LFCLK spec: %d", err);
+		return err;
+	}
+
+	LOG_DBG("LF Clock accuracy: %d", m_lfclk_specs.accuracy);
+
+	return m_lfclk_specs.accuracy;
+}
+#endif /* CONFIG_CLOCK_CONTROL_NRF2 */
+
 int32_t mpsl_clock_ctrl_init(void)
 {
 #if defined(CONFIG_MPSL_EXT_CLK_CTRL_NVM_CLOCK_REQUEST)
@@ -558,6 +580,10 @@ int32_t mpsl_clock_ctrl_init(void)
 #error "Unsupported HFCLK statup time get operation"
 #endif /* CONFIG_CLOCK_CONTROL_NRF */
 
+#if defined(CONFIG_CLOCK_CONTROL_NRF2)
+	m_nrf_lfclk_ctrl_data.accuracy_ppm = m_lfclk_accuracy_get();
+#endif /* CONFIG_CLOCK_CONTROL_NRF2 */
+
 	return mpsl_clock_ctrl_source_register(&m_nrf_lfclk_ctrl_data, &m_nrf_hfclk_ctrl_data);
 }