boards/common/qn908x: Define a common qn908x board

Boards based on the qn908x CPU will share the same OpenOCD configuration
regarding the image offset and OpenOCD commands needed to flash the
image directly with "make flash".

boards/common/qn908x/Kconfig

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+# Copyright (c) 2020 iosabi
+#
+# This file is subject to the terms and conditions of the GNU Lesser
+# General Public License v2.1. See the file LICENSE in the top level
+# directory for more details.
+
+config BOARD_COMMON_QN908X
+    bool
+    depends on CPU_FAM_QN908X
+    # Add common board support here.

boards/common/qn908x/Makefile

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+MODULE = boards_common_qn908x
+
+include $(RIOTBASE)/Makefile.base

boards/common/qn908x/Makefile.features

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+CPU ?= qn908x
+
+# Put defined MCU peripherals here (in alphabetical order)

boards/common/qn908x/Makefile.include

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+# Using dap or jlink depends on which firmware the OpenSDA debugger is running
+#DEBUG_ADAPTER ?= dap
+DEBUG_ADAPTER ?= jlink
+
+# Use the shared OpenOCD configuration
+OPENOCD_CONFIG ?= $(RIOTBOARD)/common/qn908x/dist/openocd.cfg
+
+# Disable the watchdog when flashing. OpenOCD runs a CRC program in RAM to
+# verify the image, which needs to have the WDT disabled but it is normally
+# enabled after a 'reset halt' command.
+OPENOCD_PRE_FLASH_CMDS += "-c qn908x disable_wdog"
+
+# Set default port depending on operating system
+PORT_LINUX ?= /dev/ttyACM0
+PORT_DARWIN ?= $(firstword $(sort $(wildcard /dev/tty.usbmodem*)))
+
+# OpenOCD is able to handle .elf files and is the preferred way.
+FLASHFILE ?= $(ELFFILE)
+
+# Setup serial terminal
+include $(RIOTMAKE)/tools/serial.inc.mk
+
+# This board uses OpenOCD. Note that support for QN908x in OpenOCD at the time
+# of writing has not been merged in the tree and is only available at
+# http://openocd.zylin.com/#/c/5584/ .
+include $(RIOTMAKE)/tools/openocd.inc.mk

boards/common/qn908x/dist/openocd.cfg

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+# Generic configuration for a qn908x-based board.
+
+# QN908X only supports SWD
+transport select swd
+
+# NXP QN908x.
+source [find target/qn908x.cfg]
+
+$TARGETNAME configure -event gdb-attach {
+  halt
+}
+$TARGETNAME configure -rtos auto