[nrf fromtree] drivers: clock_control: nrf: add zero-latency-isr safe APIs

Add zero latency interrupt safe APIs to allow requesting and
releasing HFXO. These will be used from components running
in zero latency interrupt context, like the bluetooth stack.

Co-authored-by: Piotr Pryga <[email protected]>

Signed-off-by: Bjarki Arge Andreasen <[email protected]>
Signed-off-by: Piotr Pryga <[email protected]>
(cherry picked from commit 2aec438)
Signed-off-by: Piotr Pryga <[email protected]>

Author: bjarki-andreasen

include/zephyr/drivers/clock_control/nrf_clock_control.h

@@ -309,6 +309,30 @@ int nrf_clock_control_cancel_or_release(const struct device *dev,
 	return api->cancel_or_release(dev, spec, cli);
 }
 
+/** @brief Request the HFXO from Zero Latency Interrupt context.
+ *
+ * Function is optimized for use in Zero Latency Interrupt context.
+ * It does not give notification when the HFXO is ready, so each
+ * user must put the request early enough to make sure the HFXO
+ * ramp-up has finished on time.
+ *
+ * This function uses reference counting so the caller must ensure
+ * that every nrf_clock_control_hfxo_request() call has a matching
+ * nrf_clock_control_hfxo_release() call.
+ */
+void nrf_clock_control_hfxo_request(void);
+
+/** @brief Release the HFXO from Zero Latency Interrupt context.
+ *
+ * Function is optimized for use in Zero Latency Interrupt context.
+ *
+ * Calls to this function must be coupled with prior calls
+ * to nrf_clock_control_hfxo_request(), because it uses basic
+ * reference counting to make sure the HFXO is released when
+ * there are no more pending requests.
+ */
+void nrf_clock_control_hfxo_release(void);
+
 #endif /* defined(CONFIG_CLOCK_CONTROL_NRF2) */
 
 /** @brief Get clock frequency that is used for the given node.