slicemk: add 1551USB3 MS88SFA board (TODO TODO TODO)

This should be squashed into "add boards" once mature.

app/boards/arm/slicemk_1551usb3_ms88sfa_blue/Kconfig

@@ -0,0 +1,4 @@
+config BOARD_ENABLE_DCDC
+	bool "Enable DCDC mode"
+	select SOC_DCDC_NRF52X
+	default y

app/boards/arm/slicemk_1551usb3_ms88sfa_blue/Kconfig.board

@@ -0,0 +1,3 @@
+config BOARD_SLICEMK_1551USB3_MS88SFA_BLUE
+	bool "SliceMK 1551USB3 MS88SFA Blue"
+	depends on SOC_NRF52840_QIAA

app/boards/arm/slicemk_1551usb3_ms88sfa_blue/Kconfig.defconfig

@@ -0,0 +1,19 @@
+if BOARD_SLICEMK_1551USB3_MS88SFA_BLUE
+
+config BOARD
+	default "SliceMK 1551USB3 MS88SFA Blue"
+
+if USB
+
+config USB_NRFX
+	default y
+
+config USB_DEVICE_STACK
+	default y
+
+endif # USB
+
+config BT_CTLR
+	default BT
+
+endif # BOARD_SLICEMK_1551USB3_MS88SFA_BLUE

app/boards/arm/slicemk_1551usb3_ms88sfa_blue/slicemk_1551usb3_ms88sfa_blue.dts

@@ -0,0 +1,94 @@
+/dts-v1/;
+#include <nordic/nrf52840_qiaa.dtsi>
+
+/ {
+	model = "SliceMK 1551USB3 MS88SFA Blue";
+
+	chosen {
+		zephyr,code-partition = &code_partition;
+		zephyr,sram = &sram0;
+		zephyr,flash = &flash0;
+		zephyr,console = &cdc_acm_uart;
+
+		zmk,backlight = &backlight;
+	};
+
+	// The dongle doesn't have a button beside the reset button but ZMK needs
+	// something to be defined for kscan. A pin that is not broken out is
+	// specified here to avoid conflicting with custom user integration using
+	// the breakout pins.
+	slicemk_button: slicemk_button {
+		compatible = "slicemk-button";
+		#gpio-cells = <2>;
+		gpio-map-mask = <0xffffffff 0xffffffc0>;
+		gpio-map-pass-thru = <0 0x3f>;
+		gpio-map = <0 0 &gpio1 1 0>;
+	};
+
+	// Use backlight to control TP4056 charger.
+	backlight: gpioleds {
+		compatible = "gpio-leds";
+		gpio_led_0 {
+			gpios = <&gpio0 8 GPIO_ACTIVE_HIGH>;
+		};
+	};
+
+	// Define PA/LNA.
+	nrf_radio_fem: fem {
+		compatible = "generic-fem-two-ctrl-pins";
+		ctx-gpios = <&gpio1 6 0>;
+		ctx-settle-time-us = <1>;
+		crx-gpios = <&gpio1 4 0>;
+		crx-settle-time-us = <1>;
+	};
+};
+
+&radio {
+	fem = <&nrf_radio_fem>;
+};
+
+&adc {
+	status = "okay";
+};
+
+&gpiote {
+	status = "okay";
+};
+
+&gpio0 {
+	status = "okay";
+};
+
+&gpio1 {
+	status = "okay";
+};
+
+&usbd {
+	status = "okay";
+	cdc_acm_uart: cdc_acm_uart {
+		compatible = "zephyr,cdc-acm-uart";
+		label = "CDC_ACM_0";
+	};
+};
+
+&flash0 {
+	partitions {
+		compatible = "fixed-partitions";
+		#address-cells = <1>;
+		#size-cells = <1>;
+
+		// Application starts at 0x1000 after the MBR.
+		code_partition: partition@1000 {
+			label = "code_partition";
+			reg = <0x00001000 0x000e9000>;
+		};
+
+		// Define storage partition before the bootloader, which starts at
+		// 0xf4000. The storage partition has been 10 pages since Adafruit
+		// bootloader version 0.6.0.
+		storage_partition: partition@ea000 {
+			label = "storage";
+			reg = <0x000ea000 0x0000a000>;
+		};
+	};
+};

app/boards/arm/slicemk_1551usb3_ms88sfa_blue/slicemk_1551usb3_ms88sfa_blue_defconfig

@@ -0,0 +1,39 @@
+CONFIG_SOC_SERIES_NRF52X=y
+CONFIG_SOC_NRF52840_QIAA=y
+CONFIG_BOARD_SLICEMK_1551USB3_MS88SFA_BLUE=y
+
+# Follow DeviceTree partition.
+CONFIG_USE_DT_CODE_PARTITION=y
+
+# Build UF2 firmware.
+CONFIG_BUILD_OUTPUT_UF2=y
+
+# Enable MPU.
+CONFIG_ARM_MPU=y
+
+# Enable hardware stack protection.
+CONFIG_HW_STACK_PROTECTION=y
+
+# Enable basic functionality.
+CONFIG_ADC=y
+CONFIG_GPIO=y
+
+# Use NVS for settings.
+CONFIG_MPU_ALLOW_FLASH_WRITE=y
+CONFIG_NVS=y
+CONFIG_SETTINGS_NVS=y
+CONFIG_FLASH=y
+CONFIG_FLASH_PAGE_LAYOUT=y
+CONFIG_FLASH_MAP=y
+
+# Set NVS sector count to reflect storage partition size.
+CONFIG_SETTINGS_NVS_SECTOR_COUNT=10
+
+# Include support for Coded PHY.
+CONFIG_BT_CTLR_PHY_CODED=y
+
+# Use backlight to control TP4056 charger.
+CONFIG_ZMK_BACKLIGHT=y
+CONFIG_ZMK_BACKLIGHT_BRT_STEP=100
+CONFIG_ZMK_BACKLIGHT_BRT_START=100
+CONFIG_ZMK_BACKLIGHT_ON_START=y