modules: hal_nordic: nrf_802154: de-escalate to non-ZLI isr

Both the nrf_802154_clock_hfclk_start() and
nrf_802154_clock_hfclk_stop() can potentially be called form ZLI and
non-ZLI contexts and consecutive calls are not guaranteed to be
alternating.

Added an implementation that uses the EGU to de-escalate to a non-ZLI
context from which it is safe to use the Zephyr API that
enables/disables the HFXO.

Signed-off-by: Rafał Kuźnia <[email protected]>

Author: e-rk

modules/hal_nordic/nrf_802154/sl_opensource/platform/nrf_802154_clock_zephyr.c

@@ -13,8 +13,35 @@
 #include <zephyr/kernel.h>
 #include <zephyr/drivers/clock_control/nrf_clock_control.h>
 #include <nrf_sys_event.h>
+#include <hal/nrf_egu.h>
 
-static bool hfclk_is_running;
+/**
+ * The implementation uses EGU to de-escalate execution context from ZLI to a regular interrupt
+ * to ensure that Zephyr APIs can be used safely.
+ *
+ * Both the nrf_802154_clock_hfclk_start() and nrf_802154_clock_hfclk_stop() can potentially be
+ * called from ZLI and non-ZLI contexts and consecutive calls are not guaranteed to be alternating.
+ *
+ * For example, it is possible that _stop() may be called multiple times in succession and the
+ * same thing applies to _start(). What is known however is that the last call always takes
+ * the precedence.
+ */
+
+#define NTF_INT NRFX_CONCAT_2(NRF_EGU_INT_TRIGGERED, NRF_802154_SL_EGU_CLOCK_CHANNEL_NO)
+#define NTF_TASK NRFX_CONCAT_2(NRF_EGU_TASK_TRIGGER, NRF_802154_SL_EGU_CLOCK_CHANNEL_NO)
+#define NTF_EVENT NRFX_CONCAT_2(NRF_EGU_EVENT_TRIGGERED, NRF_802154_SL_EGU_CLOCK_CHANNEL_NO)
+
+#define CLOCK_NONE    0u
+#define CLOCK_REQUEST 1u
+#define CLOCK_RELEASE 2u
+
+static bool hfclk_is_running = false;
+static bool enabled = false;
+static atomic_t request = CLOCK_NONE;
+
+/* Forward declarations. */
+static void hfclk_start(void);
+static void hfclk_stop(void);
 
 void nrf_802154_clock_init(void)
 {
@@ -23,11 +50,13 @@ void nrf_802154_clock_init(void)
 
 	nrf_802154_clock_hfclk_latency_set(clock_latency_us);
 #endif
+
+	nrf_egu_int_enable(NRF_802154_EGU_INSTANCE, NTF_INT);
 }
 
 void nrf_802154_clock_deinit(void)
 {
-	/* Intentionally empty. */
+	nrf_egu_int_disable(NRF_802154_EGU_INSTANCE, NTF_INT);
 }
 
 bool nrf_802154_clock_hfclk_is_running(void)
@@ -47,8 +76,44 @@ static void hfclk_on_callback(struct onoff_manager *mgr,
 	nrf_802154_clock_hfclk_ready();
 }
 
-#if defined(CONFIG_CLOCK_CONTROL_NRF)
+void nrf_802154_sl_clock_swi_irq_handler(void)
+{
+    if (nrf_egu_event_check(NRF_802154_EGU_INSTANCE, NTF_EVENT))
+    {
+        nrf_egu_event_clear(NRF_802154_EGU_INSTANCE, NTF_EVENT);
+
+	atomic_val_t previous = atomic_set(&request, CLOCK_NONE);
+
+	switch (previous) {
+		case CLOCK_REQUEST:
+			hfclk_start();
+			break;
+
+		case CLOCK_RELEASE:
+			hfclk_stop();
+			break;
+
+		default:
+			__ASSERT_NO_MSG(false);
+			break;
+	}
+    }
+}
+
 void nrf_802154_clock_hfclk_start(void)
+{
+	atomic_set(&request, CLOCK_REQUEST);
+	nrf_egu_task_trigger(NRF_802154_EGU_INSTANCE, NTF_TASK);
+}
+
+void nrf_802154_clock_hfclk_stop(void)
+{
+	atomic_set(&request, CLOCK_RELEASE);
+	nrf_egu_task_trigger(NRF_802154_EGU_INSTANCE, NTF_TASK);
+}
+
+#if defined(CONFIG_CLOCK_CONTROL_NRF)
+static void hfclk_start(void)
 {
 	struct onoff_manager *mgr =
 		z_nrf_clock_control_get_onoff(CLOCK_CONTROL_NRF_SUBSYS_HF);
@@ -57,56 +122,88 @@ void nrf_802154_clock_hfclk_start(void)
 
 	sys_notify_init_callback(&hfclk_cli.notify, hfclk_on_callback);
 
-	/*
-	 * todo: replace constlat request with PM policy API when
-	 * controlling the event latency becomes possible.
-	 */
-	if (IS_ENABLED(CONFIG_NRF_802154_CONSTLAT_CONTROL)) {
-		nrf_sys_event_request_global_constlat();
+	if (!enabled) {
+		unsigned int key = irq_lock();
+
+		/*
+		* todo: replace constlat request with PM policy API when
+		* controlling the event latency becomes possible.
+		*/
+		if (IS_ENABLED(CONFIG_NRF_802154_CONSTLAT_CONTROL)) {
+			nrf_sys_event_request_global_constlat();
+		}
+
+		int ret = onoff_request(mgr, &hfclk_cli);
+		__ASSERT_NO_MSG(ret >= 0);
+		(void)ret;
+
+		irq_unlock(key);
 	}
 
-	int ret = onoff_request(mgr, &hfclk_cli);
-	__ASSERT_NO_MSG(ret >= 0);
-	(void)ret;
+	enabled = true;
 }
 
-void nrf_802154_clock_hfclk_stop(void)
+static void hfclk_stop(void)
 {
 	struct onoff_manager *mgr =
-		z_nrf_clock_control_get_onoff(CLOCK_CONTROL_NRF_SUBSYS_HF);
+	z_nrf_clock_control_get_onoff(CLOCK_CONTROL_NRF_SUBSYS_HF);
 
 	__ASSERT_NO_MSG(mgr != NULL);
 
-	int ret = onoff_cancel_or_release(mgr, &hfclk_cli);
-	__ASSERT_NO_MSG(ret >= 0);
-	(void)ret;
+	if (enabled) {
+		unsigned int key = irq_lock();
+
+		int ret = onoff_cancel_or_release(mgr, &hfclk_cli);
+		__ASSERT_NO_MSG(ret >= 0);
+		(void)ret;
+
+		if (IS_ENABLED(CONFIG_NRF_802154_CONSTLAT_CONTROL)) {
+			nrf_sys_event_release_global_constlat();
+		}
+
+		hfclk_is_running = false;
 
-	if (IS_ENABLED(CONFIG_NRF_802154_CONSTLAT_CONTROL)) {
-		nrf_sys_event_release_global_constlat();
+		irq_unlock(key);
 	}
 
-	hfclk_is_running = false;
+	enabled = false;
 }
 
 #elif DT_NODE_HAS_STATUS(DT_NODELABEL(hfxo), okay) && \
 	DT_NODE_HAS_COMPAT(DT_NODELABEL(hfxo), nordic_nrf54h_hfxo)
 
-void nrf_802154_clock_hfclk_start(void)
+static void hfclk_start(void)
 {
-	sys_notify_init_callback(&hfclk_cli.notify, hfclk_on_callback);
-	int ret = nrf_clock_control_request(DEVICE_DT_GET(DT_NODELABEL(hfxo)), NULL, &hfclk_cli);
+	if (!enabled) {
+		unsigned int key = irq_lock();
+
+		sys_notify_init_callback(&hfclk_cli.notify, hfclk_on_callback);
+		int ret = nrf_clock_control_request(DEVICE_DT_GET(DT_NODELABEL(hfxo)), NULL, &hfclk_cli);
+
+		__ASSERT_NO_MSG(ret >= 0);
+		(void)ret;
+
+		irq_unlock(key);
+	}
 
-	__ASSERT_NO_MSG(ret >= 0);
-	(void)ret;
+	enabled = true;
 }
 
-void nrf_802154_clock_hfclk_stop(void)
+static void hfclk_stop(void)
 {
-	int ret = nrf_clock_control_cancel_or_release(DEVICE_DT_GET(DT_NODELABEL(hfxo)),
-						      NULL, &hfclk_cli);
+	if (enabled) {
+		unsigned int key = irq_lock();
+
+		int ret = nrf_clock_control_cancel_or_release(DEVICE_DT_GET(DT_NODELABEL(hfxo)),
+							NULL, &hfclk_cli);
+
+		__ASSERT_NO_MSG(ret >= 0);
+		(void)ret;
+
+		irq_unlock(key);
+	}
 
-	__ASSERT_NO_MSG(ret >= 0);
-	(void)ret;
+	enabled = false;
 }
 
 #endif