boards: arm: add QEMU support for Cortex-M0

This commit defines qemu_cortex_m0 board, adding
support for Cortex-M0 in QEMU. The added platform
is based on the (nRF51) bbc_microbit board.

Signed-off-by: Ioannis Glaropoulos <Ioannis.Glaropoulos@nordicsemi.no>

boards/arm/qemu_cortex_m0/Kconfig.board

@@ -0,0 +1,10 @@
+# Kconfig - QEMU Cortex-M0 board configuration
+#
+# Copyright (c) 2019 Nordic Semiconductor ASA.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+config BOARD_QEMU_CORTEX_M0
+	bool "Cortex-M0 Emulation (QEMU)"
+	depends on SOC_NRF51822_QFAA
+	select QEMU_TARGET

boards/arm/qemu_cortex_m0/Kconfig.defconfig

@@ -0,0 +1,12 @@
+# Kconfig - QEMU Cortex-M0 board configuration
+#
+# Copyright (c) 2019 Nordic Semiconductor ASA.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+if BOARD_QEMU_CORTEX_M0
+
+config BOARD
+	default "qemu_cortex_m0"
+
+endif # BOARD_QEMU_CORTEX_M0

boards/arm/qemu_cortex_m0/board.cmake

@@ -0,0 +1,16 @@
+#
+# Copyright (c) 2019, Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: Apache-2.0
+
+set(EMU_PLATFORM qemu)
+
+set(QEMU_CPU_TYPE_${ARCH} cortex-m0)
+set(QEMU_FLAGS_${ARCH}
+  -cpu ${QEMU_CPU_TYPE_${ARCH}}
+  -machine microbit
+  -nographic
+  -vga none
+  )
+
+board_set_debugger_ifnset(qemu)

boards/arm/qemu_cortex_m0/qemu_cortex_m0.dts

@@ -0,0 +1,72 @@
+/*
+ * Copyright (c) 2019 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/dts-v1/;
+
+#include <nordic/nrf51822_qfaa.dtsi>
+
+/ {
+	model = "QEMU Cortex-M0";
+	compatible = "nordic,nrf51822-qfaa", "nordic,nrf51822";
+
+	chosen {
+		zephyr,console = &uart0;
+		zephyr,shell-uart = &uart0;
+		zephyr,bt-mon-uart = &uart0;
+		zephyr,bt-c2h-uart = &uart0;
+		zephyr,sram = &sram0;
+		zephyr,flash = &flash0;
+		zephyr,code-partition = &slot0_partition;
+	};
+};
+
+&gpiote {
+	status = "okay";
+};
+
+&gpio0 {
+	status = "okay";
+};
+
+&uart0 {
+	status = "okay";
+	current-speed = <115200>;
+	tx-pin = <24>;
+	rx-pin = <25>;
+};
+
+&flash0 {
+	/*
+	 * For more information, see:
+	 * http://docs.zephyrproject.org/latest/guides/dts/index.html#flash-partitions
+	 */
+	partitions {
+		compatible = "fixed-partitions";
+		#address-cells = <1>;
+		#size-cells = <1>;
+
+		boot_partition: partition@0 {
+			label = "mcuboot";
+			reg = <0x00000000 0x8000>;
+		};
+		slot0_partition: partition@8000 {
+			label = "image-0";
+			reg = <0x00008000 0x1a000>;
+		};
+		slot1_partition: partition@22000 {
+			label = "image-1";
+			reg = <0x00022000 0x1a000>;
+		};
+		scratch_partition: partition@3c000 {
+			label = "image-scratch";
+			reg = <0x0003c000 0x2000>;
+		};
+		storage_partition: partition@3e000 {
+			label = "storage";
+			reg = <0x0003e000 0x00002000>;
+		};
+	};
+};

boards/arm/qemu_cortex_m0/qemu_cortex_m0.yaml

@@ -0,0 +1,16 @@
+identifier: qemu_cortex_m0
+name: QEMU Emulation for Cortex-M0
+type: qemu
+simulation: qemu
+arch: arm
+toolchain:
+  - zephyr
+  - gnuarmemb
+  - xtools
+ram: 16
+flash: 256
+testing:
+  default: true
+  ignore_tags:
+    - net
+    - bluetooth

boards/arm/qemu_cortex_m0/qemu_cortex_m0_defconfig

@@ -0,0 +1,25 @@
+# SPDX-License-Identifier: Apache-2.0
+
+CONFIG_ARM=y
+CONFIG_SOC_FAMILY_NRF=y
+CONFIG_SOC_SERIES_NRF51X=y
+CONFIG_SOC_NRF51822_QFAA=y
+CONFIG_BOARD_QEMU_CORTEX_M0=y
+
+# enable GPIO
+CONFIG_GPIO=y
+
+# clock control
+CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC=y
+CONFIG_CLOCK_CONTROL_NRF_K32SRC_250PPM=y
+
+# enable uart driver
+CONFIG_SERIAL=y
+CONFIG_UART_0_NRF_UART=y
+
+# enable console
+CONFIG_CONSOLE=y
+CONFIG_UART_CONSOLE=y
+
+# logging
+CONFIG_LOG_BUFFER_SIZE=128