drivers: ieee802154: b9x: Update cca features and function.

- Update the CCA threshold.
- Improve the CCA calculation method.

Co-authored-by: Liang Zhong <liang.zhong@telink-semi.com>
Signed-off-by: Zhenghuan Zhang <zhenghuan.zhang@telink-semi.com>

Author: 2 people

drivers/ieee802154/Kconfig.b9x

@@ -25,7 +25,7 @@ config IEEE802154_B9X_SET_TXRX_DELAY_US
 
 config IEEE802154_B9X_CCA_RSSI_THRESHOLD
 	int "CCA procedure RSSI threshold"
-	default -50
+	default -70
 	help
 	  CCA procedure returns true if the current RSSI value is less than
 	  this parameter.

drivers/ieee802154/ieee802154_b9x.c

@@ -914,13 +914,29 @@ static enum ieee802154_hw_caps b9x_get_capabilities(const struct device *dev)
 static int b9x_cca(const struct device *dev)
 {
 	ARG_UNUSED(dev);
-
+	signed char rssi_peak = -110;
+	signed char rssi_cur = -110;
+	signed int rssiSum = 0;
+	signed int cnt = 1;
 	unsigned int t1 = stimer_get_tick();
 
+	rf_set_rxmode();
+	rssi_cur = rf_get_rssi();
+	rssiSum += rssi_cur;
+
 	while (!clock_time_exceed(t1, B9X_CCA_TIME_MAX_US)) {
-		if (rf_get_rssi() < CONFIG_IEEE802154_B9X_CCA_RSSI_THRESHOLD) {
-			return 0;
-		}
+		rssi_cur = rf_get_rssi();
+		rssiSum += rssi_cur;
+		cnt++;
+	}
+
+	rssi_peak = rssiSum/cnt;
+	rf_set_tx_rx_off();
+
+	if (rssi_peak > CONFIG_IEEE802154_B9X_CCA_RSSI_THRESHOLD) {
+		return -EBUSY;
+	} else {
+		return 0;
 	}
 
 	return -EBUSY;

drivers/ieee802154/ieee802154_b9x.h

@@ -34,7 +34,7 @@
 #define B9X_TRX_LENGTH                      (256)
 #define B9X_RSSI_TO_LQI_SCALE               (3)
 #define B9X_RSSI_TO_LQI_MIN                 (-87)
-#define B9X_CCA_TIME_MAX_US                 (200)
+#define B9X_CCA_TIME_MAX_US                 (120)
 #define B9X_LOGIC_CHANNEL_TO_PHYSICAL(p)    (((p) - 10) * 5)
 #define B9X_MAC_KEYS_ITEMS                  (3)
 #ifndef IEEE802154_CRYPTO_LENGTH_AES_BLOCK