feat(battery)!: Add chosen node for battery

battery.c now uses the zmk,battery chosen node to select a battery
sensor. Using the node labeled "BATTERY" is maintained for backwards
compatibility but is now deprecated. Custom boards should switch to
using the chosen node.

# Conflicts:
#	app/boards/arm/bluemicro840/bluemicro840_v1.dts
#	app/boards/arm/nice60/nice60.dts
#	app/boards/arm/nrfmicro/nrfmicro_13.dts

# Conflicts:
#	app/boards/arm/bluemicro840/bluemicro840_v1.dts

app/boards/arm/bluemicro840/bluemicro840_v1.dts

@@ -17,6 +17,7 @@
 		zephyr,sram = &sram0;
 		zephyr,flash = &flash0;
 		zephyr,console = &cdc_acm_uart;
+		zmk,battery = &vbatt;
 	};
 
 	leds {
@@ -34,7 +35,7 @@
 		control-gpios = <&gpio0 12 GPIO_ACTIVE_HIGH>;
 	};
 
-	vbatt {
+	vbatt: vbatt {
 		compatible = "zmk,battery-voltage-divider";
 		label = "BATTERY";
 		io-channels = <&adc 7>;

app/boards/arm/bt60/bt60.dtsi

@@ -17,6 +17,7 @@
 		zephyr,sram = &sram0;
 		zephyr,flash = &flash0;
 		zephyr,console = &cdc_acm_uart;
+		zmk,battery = &vbatt;
 		zmk,kscan = &kscan0;
 		zmk,matrix_transform = &default_transform;
 	};
@@ -46,7 +47,7 @@
 		};
 	};
 
-	vbatt {
+	vbatt: vbatt {
 		compatible = "zmk,battery-voltage-divider";
 		label = "BATTERY";
 		io-channels = <&adc 2>;

app/boards/arm/mikoto/mikoto_520.dts

@@ -17,6 +17,7 @@
 		zephyr,sram = &sram0;
 		zephyr,flash = &flash0;
 		zephyr,console = &cdc_acm_uart;
+		zmk,battery = &vbatt;
 	};
 
 	leds {
@@ -34,7 +35,7 @@
 		init-delay-ms = <50>;
 	};
 
-	vbatt {
+	vbatt: vbatt {
 		compatible = "zmk,battery-voltage-divider";
 		label = "BATTERY";
 		io-channels = <&adc 2>;

app/boards/arm/nice60/nice60.dts

@@ -19,6 +19,7 @@
 		zephyr,sram = &sram0;
 		zephyr,flash = &flash0;
 		zephyr,console = &cdc_acm_uart;
+		zmk,battery = &vbatt;
 		zmk,kscan = &kscan0;
 		zmk,matrix_transform = &default_transform;
 		zmk,underglow = &led_strip;
@@ -81,7 +82,7 @@ RC(4,0)   RC(4,1)   RC(4,2)                      RC(4,5)                       R
 		control-gpios = <&gpio0 5 GPIO_ACTIVE_LOW>;
 	};
 
-	vbatt {
+	vbatt: vbatt {
 		compatible = "zmk,battery-voltage-divider";
 		label = "BATTERY";
 		io-channels = <&adc 2>;

app/boards/arm/nice_nano/nice_nano.dts

@@ -8,13 +8,17 @@
 #include "nice_nano.dtsi"
 
 / {
+	chosen {
+		zmk,battery = &vbatt;
+	};
+
 	ext-power {
 		compatible = "zmk,ext-power-generic";
 		label = "EXT_POWER";
 		control-gpios = <&gpio0 13 GPIO_ACTIVE_LOW>;
 	};
 
-	vbatt {
+	vbatt: vbatt {
 		compatible = "zmk,battery-voltage-divider";
 		label = "BATTERY";
 		io-channels = <&adc 2>;

app/boards/arm/nice_nano/nice_nano_v2.dts

@@ -8,6 +8,10 @@
 #include "nice_nano.dtsi"
 
 / {
+	chosen {
+		zmk,battery = &vbatt;
+	};
+
 	ext-power {
 		compatible = "zmk,ext-power-generic";
 		label = "EXT_POWER";
@@ -15,7 +19,7 @@
 		init-delay-ms = <50>;
 	};
 
-	vbatt {
+	vbatt: vbatt {
 		compatible = "zmk,battery-nrf-vddh";
 		label = "BATTERY";
 	};

app/boards/arm/nrfmicro/nrfmicro_13.dts

@@ -17,6 +17,7 @@
 		zephyr,sram = &sram0;
 		zephyr,flash = &flash0;
 		zephyr,console = &cdc_acm_uart;
+		zmk,battery = &vbatt;
 	};
 
 	leds {
@@ -33,7 +34,7 @@
 		control-gpios = <&gpio1 9 GPIO_ACTIVE_LOW>;
 	};
 
-	vbatt {
+	vbatt: vbatt {
 		compatible = "zmk,battery-voltage-divider";
 		label = "BATTERY";
 		io-channels = <&adc 2>;

app/boards/arm/s40nc/s40nc.dts

@@ -17,6 +17,7 @@
 		zephyr,sram = &sram0;
 		zephyr,flash = &flash0;
 		zephyr,console = &cdc_acm_uart;
+		zmk,battery = &vbatt;
 		zmk,kscan = &kscan0;
 		zmk,matrix_transform = &default_transform;
 	};
@@ -69,7 +70,7 @@
 		};
 	};
 
-	vbatt {
+	vbatt: vbatt {
 		compatible = "zmk,battery-voltage-divider";
 		label = "BATTERY";
 		io-channels = <&adc 2>;

app/boards/seeeduino_xiao_ble.overlay

@@ -8,9 +8,10 @@
 / {
 	chosen {
 		zephyr,console = &cdc_acm_uart;
+		zmk,battery = &vbatt;
 	};
 
-	vbatt {
+	vbatt: vbatt {
 		compatible = "zmk,battery-voltage-divider";
 		label = "BATTERY";
 		io-channels = <&adc 7>;

app/src/battery.c

@@ -5,6 +5,7 @@
  */
 
 #include <device.h>
+#include <devicetree.h>
 #include <init.h>
 #include <kernel.h>
 #include <drivers/sensor.h>
@@ -18,12 +19,16 @@ LOG_MODULE_DECLARE(zmk, CONFIG_ZMK_LOG_LEVEL);
 #include <zmk/battery.h>
 #include <zmk/events/battery_state_changed.h>
 
-const struct device *battery;
-
 static uint8_t last_state_of_charge = 0;
 
 uint8_t zmk_battery_state_of_charge() { return last_state_of_charge; }
 
+#if DT_HAS_CHOSEN(zmk_battery)
+static const struct device *const battery = DEVICE_DT_GET(DT_CHOSEN(zmk_battery));
+#else
+static const struct device *battery;
+#endif
+
 static int zmk_battery_update(const struct device *battery) {
     struct sensor_value state_of_charge;
 
@@ -75,10 +80,18 @@ static void zmk_battery_timer(struct k_timer *timer) { k_work_submit(&battery_wo
 K_TIMER_DEFINE(battery_timer, zmk_battery_timer, NULL);
 
 static int zmk_battery_init(const struct device *_arg) {
+#if !DT_HAS_CHOSEN(zmk_battery)
     battery = device_get_binding("BATTERY");
 
     if (battery == NULL) {
-        LOG_DBG("No battery device labelled BATTERY found.");
+        return -ENODEV;
+    }
+
+    LOG_WRN("Finding battery device labeled BATTERY is deprecated. Use zmk,battery chosen node.");
+#endif
+
+    if (!device_is_ready(battery)) {
+        LOG_ERR("Battery device \"%s\" is not ready", battery->name);
         return -ENODEV;
     }