[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]>

include/zephyr/drivers/clock_control/nrf_clock_control.h

@@ -317,6 +317,30 @@ 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.