drivers: ieee802154: nrf5: new RX window cancels previous RX

According to the documentation of IEEE802154_CONFIG_RX_SLOT,
if the previous RX slot hasn't begun yet, but a new one is scheduled,
then the previous RX slot must be cancelled. The new RX slot effectively
replaces the old one.

If the previous slot is currently ongoing, then it is not affected. The
new RX slot can be scheduled while the previous slot is still ongoing.

Signed-off-by: Rafał Kuźnia <rafal.kuznia@nordicsemi.no>

Author: e-rk

drivers/ieee802154/ieee802154_nrf5.c

@@ -67,7 +67,8 @@ static struct nrf5_802154_data nrf5_data;
 static const struct device *nrf5_dev;
 #endif
 
-#define DRX_SLOT_RX 0 /* Delayed reception window ID */
+#define DRX_SLOT_RX_PRIMARY 0 /* Primary delayed reception window ID */
+#define DRX_SLOT_RX_SECONDARY 1 /* Secondary delayed reception window ID */
 
 #define NSEC_PER_TEN_SYMBOLS (10 * IEEE802154_PHY_OQPSK_780_TO_2450MHZ_SYMBOL_PERIOD_NS)
 
@@ -855,6 +856,38 @@ static void nrf5_config_mac_keys(struct ieee802154_key *mac_keys)
 }
 #endif /* CONFIG_NRF_802154_ENCRYPTION */
 
+#if defined(CONFIG_IEEE802154_CSL_ENDPOINT)
+
+static void nrf5_receive_at(const struct ieee802154_config *config)
+{
+	bool primary_cancel = nrf_802154_receive_at_scheduled_cancel(DRX_SLOT_RX_PRIMARY);
+	bool secondary_cancel = nrf_802154_receive_at_scheduled_cancel(DRX_SLOT_RX_SECONDARY);
+
+	if (!primary_cancel && !secondary_cancel) {
+		/* Edge case: In between the primary and secondary slot cancellation
+		 *            the secondary RX slot might have started. Due to ordering
+		 *            of the above two cancellations we can assume that the primary
+		 *            slot is already free.
+		 */
+		primary_cancel = true;
+	}
+
+	uint32_t slot_id = primary_cancel ? DRX_SLOT_RX_PRIMARY : DRX_SLOT_RX_SECONDARY;
+
+	/* Note that even if the nrf_802154_receive_at function is not called in time
+	 * (for example due to the call being blocked by higher priority threads) and
+	 * the delayed reception window is not scheduled, the CSL phase will still be
+	 * calculated as if the following reception windows were at times
+	 * anchor_time + n * csl_period. The previously set
+	 * anchor_time will be used for calculations.
+	 */
+	nrf_802154_receive_at(config->rx_slot.start / NSEC_PER_USEC,
+			      config->rx_slot.duration / NSEC_PER_USEC,
+			      config->rx_slot.channel, slot_id);
+}
+
+#endif /* CONFIG_IEEE802154_CSL_ENDPOINT */
+
 static int nrf5_configure(const struct device *dev,
 			  enum ieee802154_config_type type,
 			  const struct ieee802154_config *config)
@@ -1011,16 +1044,7 @@ static int nrf5_configure(const struct device *dev,
 	} break;
 
 	case IEEE802154_CONFIG_RX_SLOT: {
-		/* Note that even if the nrf_802154_receive_at function is not called in time
-		 * (for example due to the call being blocked by higher priority threads) and
-		 * the delayed reception window is not scheduled, the CSL phase will still be
-		 * calculated as if the following reception windows were at times
-		 * anchor_time + n * csl_period. The previously set
-		 * anchor_time will be used for calculations.
-		 */
-		nrf_802154_receive_at(config->rx_slot.start / NSEC_PER_USEC,
-				      config->rx_slot.duration / NSEC_PER_USEC,
-				      config->rx_slot.channel, DRX_SLOT_RX);
+		nrf5_receive_at(config);
 	} break;
 
 	case IEEE802154_CONFIG_CSL_PERIOD: {
@@ -1136,7 +1160,8 @@ void nrf_802154_receive_failed(nrf_802154_rx_error_t error, uint32_t id)
 	const struct device *dev = nrf5_get_device();
 
 #if defined(CONFIG_IEEE802154_CSL_ENDPOINT)
-	if (id == DRX_SLOT_RX && error == NRF_802154_RX_ERROR_DELAYED_TIMEOUT) {
+	if ((id == DRX_SLOT_RX_PRIMARY || id == DRX_SLOT_RX_SECONDARY)
+	    && error == NRF_802154_RX_ERROR_DELAYED_TIMEOUT) {
 		if (!nrf5_data.rx_on_when_idle) {
 			/* Transition to RxOff done automatically by the driver */
 			return;