circuitpython/ports/atmel-samd/reset.c

/*
 * This file is part of the MicroPython project, http://micropython.org/
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2017 Scott Shawcroft for Adafruit Industries
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include "reset.h"

#include "include/sam.h"
#include "supervisor/filesystem.h"

// Copied from inc/uf2.h in https://github.com/Microsoft/uf2-samd21
#ifdef SAMD21
#define DBL_TAP_PTR ((volatile uint32_t *)(HMCRAMC0_ADDR + HMCRAMC0_SIZE - 4))
#else
    #ifdef SAMD51
    #define DBL_TAP_PTR ((volatile uint32_t *)(HSRAM_ADDR + HSRAM_SIZE - 4))
    #endif
#endif
#define DBL_TAP_MAGIC 0xf01669ef // Randomly selected, adjusted to have first and last bit set

void reset_to_bootloader(void) {
    filesystem_flush();
    *DBL_TAP_PTR = DBL_TAP_MAGIC;
    NVIC_SystemReset();
}