drivers: lora: Add support for setting sync-word and iq-inverted

Add support for setting sync-word and iq-inverted in lora_modem_config. By
being able to set the sync-word it's possible to send "raw" public-network
packets using lora_send and using iq-inverted both uplink and downlink
messages can be sent.

Signed-off-by: Tim Cooijmans <timcooijmans@gmail.com>

drivers/lora/sx12xx_common.c

@@ -316,15 +316,17 @@ int sx12xx_lora_config(const struct device *dev,
 		Radio.SetTxConfig(MODEM_LORA, config->tx_power, 0,
 				  config->bandwidth, config->datarate,
 				  config->coding_rate, config->preamble_len,
-				  false, true, 0, 0, false, 4000);
+				  false, true, 0, 0, config->iq_inverted, 4000);
 	} else {
 		/* TODO: Get symbol timeout value from config parameters */
 		Radio.SetRxConfig(MODEM_LORA, config->bandwidth,
 				  config->datarate, config->coding_rate,
 				  0, config->preamble_len, 10, false, 0,
-				  false, 0, 0, false, true);
+				  false, 0, 0, config->iq_inverted, true);
 	}
 
+	Radio.SetPublicNetwork(config->public_network);
+
 	modem_release(&dev_data);
 	return 0;
 }

include/zephyr/drivers/lora.h

@@ -66,6 +66,26 @@ struct lora_modem_config {
 
 	/* Set to true for transmission, false for receiving */
 	bool tx;
+
+	/**
+	 * Invert the In-Phase and Quadrature (IQ) signals. Normally this
+	 * should be set to false. In advanced use-cases where a
+	 * differentation is needed between "uplink" and "downlink" traffic,
+	 * the IQ can be inverted to create two different channels on the
+	 * same frequency
+	 */
+	bool iq_inverted;
+
+	/**
+	 * Sets the sync-byte to use:
+	 *  - false: for using the private network sync-byte
+	 *  - true:  for using the public network sync-byte
+	 * The public network sync-byte is only intended for advanced usage.
+	 * Normally the private network sync-byte should be used for peer
+	 * to peer communications and the LoRaWAN APIs should be used for
+	 * interacting with a public network.
+	 */
+	bool public_network;
 };
 
 /**