Move board reset and entering bootloader to to board_common api

Define modes of reset and way to tell the system to enter
  the bootloader via an api defined in board_common.h

  If hardware or simulation deo not support the reset or
  bootloader API and can define BOARD_HAS_NO_RESET and
  BOARD_HAS_NO_BOOTLOADER respectivly.

src/drivers/boards/common/board_common.h

@@ -185,6 +185,14 @@
 #endif
 
 
+/************************************************************************************
+ * Public Data
+ ************************************************************************************/
+typedef enum board_reset_e {
+	board_reset_normal     = 0,
+	board_reset_extended     = 1,
+	board_reset_enter_bootloader = 2
+} board_reset_e;
 /************************************************************************************
  * Private Functions
  ************************************************************************************/
@@ -241,3 +249,30 @@ __EXPORT int board_get_dma_usage(uint16_t *dma_total, uint16_t *dma_used, uint16
 __EXPORT void board_rc_input(bool invert_on);
 #  endif
 #endif
+
+/************************************************************************************
+ * Name: board_reset
+ *
+ * Description:
+ *   All boards my optionally provide this API to reset the board
+ *
+ ************************************************************************************/
+#if defined(BOARD_HAS_NO_RESET)
+#  define board_system_reset(status)
+#else
+__EXPORT void board_system_reset(int status) noreturn_function;
+#endif
+/************************************************************************************
+ * Name: board_set_bootload_mode
+ *
+ * Description:
+ *   All boards my optionally provide this API to enter configure the entry to
+ *   boot loade mode on the next system reset.
+ *
+ ************************************************************************************/
+
+#if defined(BOARD_HAS_NO_BOOTLOADER)
+#  define board_set_bootload_mode(mode)
+#else
+__EXPORT int board_set_bootload_mode(board_reset_e mode);
+#endif

src/drivers/boards/common/stm32/board_reset.c

@@ -0,0 +1,75 @@
+/****************************************************************************
+ *
+ *   Copyright (C) 2017 PX4 Development Team. All rights reserved.
+ *   Author: @author David Sidrane <david_s5@nscdg.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/**
+ * @file board_reset.c
+ * Implementation of STM32 based Board RESET API
+ */
+
+#include <px4_config.h>
+#include <errno.h>
+#include <stm32_pwr.h>
+#include <nuttx/board.h>
+
+
+int board_set_bootload_mode(board_reset_e mode)
+{
+	uint32_t regvalue = 0;
+
+	switch (mode) {
+	case board_reset_normal:
+	case board_reset_extended:
+		break;
+
+	case board_reset_enter_bootloader:
+		regvalue = 0xb007b007;
+		break;
+
+	default:
+		return -EINVAL;
+	}
+
+	stm32_pwr_enablebkp(true);
+	*(uint32_t *)STM32_BKP_BASE = regvalue;
+	stm32_pwr_enablebkp(false);
+	return OK;
+}
+
+
+void board_system_reset(int status)
+{
+	board_reset(status);
+
+	while (1);
+}