boards: seeed: xiao_esp32c6 external antenna support

This PR adds adds The RF switch node and support for
the extenal antenna.

Signed-off-by: Mario Paja <mariopaja@hotmail.com>

Author: mariopaja

boards/seeed/xiao_esp32c6/CMakeLists.txt

@@ -0,0 +1,10 @@
+#
+# Copyright (c) 2025 Mario Paja
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+if(CONFIG_ESP32_EXT_ANTENNA)
+  zephyr_library()
+  zephyr_library_sources(board.c)
+endif()

boards/seeed/xiao_esp32c6/Kconfig

@@ -5,3 +5,8 @@ config HEAP_MEM_POOL_ADD_SIZE_BOARD
 	int
 	default 4096 if BOARD_XIAO_ESP32C6_ESP32C6_HPCORE
 	default 256 if BOARD_XIAO_ESP32C6_ESP32C6_LPCORE
+
+config XIAO_ESP32C6_EXT_ANTENNA
+	bool "XIAO ESP32C6 external antenna configuration"
+	default y if BOARD_XIAO_ESP32C6_ESP32C6_HPCORE && ESP32_EXT_ANTENNA
+	select BOARD_LATE_INIT_HOOK

boards/seeed/xiao_esp32c6/board.c

@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2025 Mario Paja
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr/kernel.h>
+#include <zephyr/drivers/gpio.h>
+#include <zephyr/init.h>
+
+void board_late_init_hook(void)
+{
+#if DT_NODE_HAS_STATUS_OKAY(DT_NODELABEL(rf_switch))
+	const struct gpio_dt_spec rf_switch_en =
+		GPIO_DT_SPEC_GET(DT_NODELABEL(rf_switch), enable_gpios);
+
+	if (gpio_is_ready_dt(&rf_switch_en)) {
+		gpio_pin_configure_dt(&rf_switch_en, GPIO_OUTPUT_ACTIVE);
+	}
+
+	const struct gpio_dt_spec ant_sel = GPIO_DT_SPEC_GET(DT_NODELABEL(rf_switch), select_gpios);
+
+	if (gpio_is_ready_dt(&ant_sel)) {
+#ifdef CONFIG_XIAO_ESP32C6_EXT_ANTENNA
+		gpio_pin_configure_dt(&ant_sel, GPIO_OUTPUT_ACTIVE);
+#else
+		gpio_pin_configure_dt(&ant_sel, GPIO_OUTPUT_INACTIVE);
+#endif /* XIAO_ESP32C6_EXT_ANTENNA */
+	}
+
+#endif /* DT_NODE_HAS_STATUS_OKAY(DT_NODELABEL(rf_switch)) */
+}

boards/seeed/xiao_esp32c6/dts/bindings/seeed,xiao-gpio-rf-switch.yaml

@@ -0,0 +1,20 @@
+# Copyright (c) 2025 Mario Paja
+# SPDX-License-Identifier: Apache-2.0
+
+description: |
+  Group of GPIO-controlled relays used to enable an RF switch and select the active antenna.
+
+compatible: "seeed,xiao-gpio-rf-switch"
+
+properties:
+  enable-gpios:
+    type: phandle-array
+    required: true
+    description: |
+      GPIOs to enable the RF switch module.
+
+  select-gpios:
+    type: phandle-array
+    required: true
+    description: |
+      GPIOs to select the active antenna

boards/seeed/xiao_esp32c6/xiao_esp32c6_hpcore.dts

@@ -38,6 +38,11 @@
 		watchdog0 = &wdt0;
 	};
 
+	rf_switch: rf_switch {
+		compatible = "seeed,xiao-gpio-rf-switch";
+		enable-gpios = <&gpio0 3 GPIO_ACTIVE_LOW>;
+		select-gpios = <&gpio0 14 GPIO_ACTIVE_HIGH>;
+	};
 };
 
 &trng0 {

soc/espressif/common/Kconfig

@@ -58,6 +58,13 @@ config ESP32_SW_COEXIST_ENABLE
 	  If only Bluetooth is used, it is recommended to disable this option to reduce binary file
 	  size.
 
+config ESP32_EXT_ANTENNA
+	bool "ESP32 External Antenna Selector"
+	help
+	  Select the external antenna of custom ESP32 boards.
+	  By default, the onboard antenna is used.
+	  A board late init hook is required to enable and select the external antenna.
+
 endif
 
 rsource "Kconfig.amp"