supervise.c

/*
 * This file is part of the TREZOR project, https://trezor.io/
 *
 * Copyright (C) 2018 Jochen Hoenicke <hoenicke@gmail.com>
 *
 * This library is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This library 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <libopencm3/stm32/flash.h>
#include <stdint.h>
#include "supervise.h"
#include "memory.h"

#if !EMULATOR

static void svhandler_flash_unlock(void) {
	flash_clear_status_flags();
	flash_unlock();
}

static void svhandler_flash_program(uint32_t psize) {
	/* Wait for any write operation to complete. */
	flash_wait_for_last_operation();
	/* check program size argument */
	if (psize != FLASH_CR_PROGRAM_X8
		&& psize != FLASH_CR_PROGRAM_X16
		&& psize != FLASH_CR_PROGRAM_X32
		&& psize != FLASH_CR_PROGRAM_X64)
		return;
	FLASH_CR = (FLASH_CR & ~(FLASH_CR_PROGRAM_MASK << FLASH_CR_PROGRAM_SHIFT))
		| (psize << FLASH_CR_PROGRAM_SHIFT);
	FLASH_CR |= FLASH_CR_PG;
}

static void svhandler_flash_erase_sector(uint16_t sector) {
	/* we only allow erasing meta sectors 2 and 3. */
	if (sector < FLASH_META_SECTOR_FIRST ||
		sector > FLASH_META_SECTOR_LAST) {
		return;
	}
	flash_erase_sector(sector, FLASH_CR_PROGRAM_X32);
}

static uint32_t svhandler_flash_lock(void) {
	/* Wait for any write operation to complete. */
	flash_wait_for_last_operation();
	/* Disable writes to flash. */
	FLASH_CR &= ~FLASH_CR_PG;
	/* lock flash register */
	FLASH_CR |= FLASH_CR_LOCK;
	/* return flash status register */
	return FLASH_SR;
}

extern volatile uint32_t system_millis;

void svc_handler_main(uint32_t *stack) {
	uint8_t svc_number = ((uint8_t*) stack[6])[-2];
	switch (svc_number) {
	case SVC_FLASH_UNLOCK:
		svhandler_flash_unlock();
		break;
	case SVC_FLASH_PROGRAM:
		svhandler_flash_program(stack[0]);
		break;
	case SVC_FLASH_ERASE:
		svhandler_flash_erase_sector(stack[0]);
		break;
	case SVC_FLASH_LOCK:
		stack[0] = svhandler_flash_lock();
		break;
	case SVC_TIMER_MS:
		stack[0] = system_millis;
		break;
	default:
		stack[0] = 0xffffffff;
		break;
	}
}

#endif