drivers: ieee802154: cc13/26xx_subg: improve CSMA/CA compliance

Switch the driver to the soft CSMA/CA algorithm as an intermediate
compromise for improved standard compliance (namely expontential
backoff) until true hardware support can be implemented by chaining
radio commands.

Signed-off-by: Florian Grandel <fgrandel@code-for-humans.de>

drivers/ieee802154/Kconfig.cc13xx_cc26xx

@@ -90,13 +90,10 @@ config IEEE802154_CC13XX_CC26XX_SUB_GHZ_INIT_PRIO
 	  Set the initialization priority number.
 
 config IEEE802154_CC13XX_CC26XX_SUB_GHZ_RADIO_TX_RETRIES
-	int "Radio Transmission attempts"
-	default NET_L2_IEEE802154_RADIO_TX_RETRIES if NET_L2_IEEE802154
-	default 3
-	range 1 7
+	bool
+	select DEPRECATED
 	help
-	  Number of transmission attempts radio driver should do, before
-	  replying it could not send the packet.
+	  DEPRECATED - use NET_L2_IEEE802154_RADIO_TX_RETRIES instead
 
 config IEEE802154_CC13XX_CC26XX_SUB_GHZ_CUSTOM_RADIO_SETUP
 	bool "Use custom radio setup structures (advanced)"

drivers/ieee802154/ieee802154_cc13xx_cc26xx_subg.c

@@ -358,9 +358,7 @@ static enum ieee802154_hw_caps
 ieee802154_cc13xx_cc26xx_subg_get_capabilities(const struct device *dev)
 {
 	/* TODO: enable IEEE802154_HW_FILTER */
-	/* TODO: remove or actually implement IEEE802154_HW_CSMA */
-	return IEEE802154_HW_FCS | IEEE802154_HW_CSMA
-	       | IEEE802154_HW_SUB_GHZ;
+	return IEEE802154_HW_FCS | IEEE802154_HW_SUB_GHZ;
 }
 
 static int ieee802154_cc13xx_cc26xx_subg_cca(const struct device *dev)
@@ -509,13 +507,12 @@ static int ieee802154_cc13xx_cc26xx_subg_tx(const struct device *dev,
 					    struct net_buf *buf)
 {
 	struct ieee802154_cc13xx_cc26xx_subg_data *drv_data = dev->data;
-	int retry = CONFIG_IEEE802154_CC13XX_CC26XX_SUB_GHZ_RADIO_TX_RETRIES;
 	RF_EventMask events;
 	int ret;
 
-	if (mode != IEEE802154_TX_MODE_CSMA_CA) {
-		NET_ERR("TX mode %d not supported", mode);
-		return -ENOTSUP;
+	if (mode != IEEE802154_TX_MODE_DIRECT) {
+		/* For backwards compatibility we only log an error but do not bail. */
+		NET_ERR("TX mode %d not supported - sending directly instead.", mode);
 	}
 
 	k_mutex_lock(&drv_data->tx_mutex, K_FOREVER);
@@ -530,67 +527,36 @@ static int ieee802154_cc13xx_cc26xx_subg_tx(const struct device *dev,
 	/* TODO: Zero-copy TX, see discussion in #49775. */
 	memcpy(&drv_data->tx_data[IEEE802154_PHY_SUN_FSK_PHR_LEN], buf->data, buf->len);
 
-	/* Chain commands */
-	drv_data->cmd_prop_cs.pNextOp =
-		(rfc_radioOp_t *) &drv_data->cmd_prop_tx_adv;
-	drv_data->cmd_prop_cs.condition.rule = COND_STOP_ON_TRUE;
-
 	/* Set TX data */
 	drv_data->cmd_prop_tx_adv.pktLen = buf->len + IEEE802154_PHY_SUN_FSK_PHR_LEN;
 	drv_data->cmd_prop_tx_adv.pPkt = drv_data->tx_data;
 
+	/* Reset command status */
+	drv_data->cmd_prop_tx_adv.status = IDLE;
+	drv_data->cmd_prop_tx_adv.pNextOp = NULL;
+
 	/* Abort FG and BG processes */
 	ret = ieee802154_cc13xx_cc26xx_subg_stop(dev);
 	if (ret < 0) {
 		ret = -EIO;
 		goto out;
 	}
 
-	do {
-		/* Reset command status */
-		drv_data->cmd_prop_cs.status = IDLE;
-		drv_data->cmd_prop_tx_adv.status = IDLE;
-
-		events = RF_runCmd(drv_data->rf_handle,
-				   (RF_Op *)&drv_data->cmd_prop_cs,
-				   RF_PriorityNormal, cmd_prop_tx_adv_callback,
-				   RF_EventLastCmdDone);
-		if ((events & RF_EventLastCmdDone) == 0) {
-			LOG_DBG("Failed to run command (%" PRIx64 ")", events);
-			ret = -EIO;
-			goto out;
-		}
-
-		if (drv_data->cmd_prop_cs.status != PROP_DONE_IDLE) {
-			LOG_DBG("Channel access failure (0x%x)",
-				drv_data->cmd_prop_cs.status);
-			/* TODO: This is not a compliant CSMA/CA algorithm, use soft CSMA/CA
-			 *       instead as the SubGHz radio of this SoC has no HW CSMA/CA backoff
-			 *       algorithm support as required by IEEE 802.15.4, section 6.2.5.1.
-			 *       Alternatively construct compliant CSMA/CA with a combination
-			 *       of CMD_NOP, CMD_PROP_CS and CMD_COUNT_BRANCH commands, see
-			 *       SimpleLink SDK (rfListenBeforeTalk.c) or calculate proper backoff
-			 *       period as in the SimpleLink WiSUN stack's mac_tx.c.
-			 * Currently, we just wait a random amount of us in the range [0,256).
-			 */
-			k_busy_wait(sys_rand32_get() & 0xff);
-			continue;
-		}
-
-		if (drv_data->cmd_prop_tx_adv.status != PROP_DONE_OK) {
-			LOG_DBG("Transmit failed (0x%x)",
-				drv_data->cmd_prop_tx_adv.status);
-			continue;
-		}
-
-		/* TODO: handle RX acknowledgment */
-		ret = 0;
+	events = RF_runCmd(drv_data->rf_handle, (RF_Op *)&drv_data->cmd_prop_tx_adv,
+			   RF_PriorityNormal, cmd_prop_tx_adv_callback, RF_EventLastCmdDone);
+	if ((events & RF_EventLastCmdDone) == 0) {
+		LOG_DBG("Failed to run command (%" PRIx64 ")", events);
+		ret = -EIO;
 		goto out;
+	}
 
-	} while (retry-- > 0);
+	if (drv_data->cmd_prop_tx_adv.status != PROP_DONE_OK) {
+		LOG_DBG("Transmit failed (0x%x)", drv_data->cmd_prop_tx_adv.status);
+		ret = -EIO;
+		goto out;
+	}
 
-	LOG_DBG("Failed to TX");
-	ret = -EIO;
+	/* TODO: handle RX acknowledgment */
 
 out:
 	(void)ieee802154_cc13xx_cc26xx_subg_rx(dev);