Initial pass of F405 support (#14584)

* Initial pass of F405 support

* remove some conf files

* docs

* clang

keyboards/handwired/onekey/stm32f405_feather/config.h

@@ -0,0 +1,25 @@
+/* Copyright 2019
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include "config_common.h"
+
+#define PRODUCT Onekey Adafruit Feather STM32F405
+
+#define MATRIX_COL_PINS { C2 }
+#define MATRIX_ROW_PINS { C3 }
+#define UNUSED_PINS

keyboards/handwired/onekey/stm32f405_feather/readme.md

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+# Adafruit Feather STM32F405 Express onekey
+
+* Supported Hardware: [Adafruit Feather STM32F405 Express](https://www.adafruit.com/product/4382)
+
+To trigger keypress, short together pins *GPIO 12 / PC2* and *GPIO 11 / PC3*.
+
+https://learn.adafruit.com/adafruit-stm32f405-feather-express/dfu-bootloader-details#enabling-dfu-bootloader-mode-3045622-2

keyboards/handwired/onekey/stm32f405_feather/rules.mk

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+# MCU name
+MCU = STM32F405
+
+# Bootloader selection
+BOOTLOADER = stm32-dfu
+
+# Enter lower-power sleep mode when on the ChibiOS idle thread
+OPT_DEFS += -DCORTEX_ENABLE_WFI_IDLE=TRUE