subsys/dfu/boot/mcuboot.c

/*
 * Copyright (c) 2017 Nordic Semiconductor ASA
 * Copyright (c) 2016-2017 Linaro Limited
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#include <stddef.h>
#include <errno.h>
#include <string.h>
#include <flash.h>
#include <zephyr.h>
#include <init.h>

#include <misc/__assert.h>
#include <misc/byteorder.h>
#include <board.h>
#include <dfu/mcuboot.h>

/*
 * Helpers for image headers and trailers, as defined by mcuboot.
 */

/*
 * Strict defines: the definitions in the following block contain
 * values which are MCUboot implementation requirements.
 */

/* Header: */
#define BOOT_HEADER_MAGIC_V1 0x96f3b83d
#define BOOT_HEADER_SIZE_V1 32

/* Trailer: */
#define BOOT_MAX_ALIGN 8
#define BOOT_MAGIC_SZ  16
#define BOOT_FLAG_SET 0x01
#define BOOT_FLAG_UNSET 0xff

/*
 * Raw (on-flash) representation of the v1 image header.
 */
struct mcuboot_v1_raw_header {
	u32_t header_magic;
	u32_t image_load_address;
	u16_t header_size;
	u16_t pad;
	u32_t image_size;
	u32_t image_flags;
	struct {
		u8_t major;
		u8_t minor;
		u16_t revision;
		u32_t build_num;
	} version;
	u32_t pad2;
} __packed;

/*
 * End of strict defines
 */

#define BOOT_MAGIC_GOOD  1
#define BOOT_MAGIC_BAD   2
#define BOOT_MAGIC_UNSET 3

#define BOOT_FLAG_IMAGE_OK 0
#define BOOT_FLAG_COPY_DONE 1

#define FLASH_MIN_WRITE_SIZE FLASH_WRITE_BLOCK_SIZE
#define FLASH_BANK0_OFFSET FLASH_AREA_IMAGE_0_OFFSET

/* FLASH_AREA_IMAGE_XX_YY values used below are auto-generated thanks to DT */
#define FLASH_BANK_SIZE FLASH_AREA_IMAGE_0_SIZE
#define FLASH_BANK1_OFFSET FLASH_AREA_IMAGE_1_OFFSET
#define FLASH_STATE_OFFSET (FLASH_AREA_IMAGE_SCRATCH_OFFSET +\
			    FLASH_AREA_IMAGE_SCRATCH_SIZE)

#define COPY_DONE_OFFS(bank_offs) (bank_offs + FLASH_BANK_SIZE -\
				   BOOT_MAGIC_SZ - BOOT_MAX_ALIGN * 2)

#define IMAGE_OK_OFFS(bank_offs) (bank_offs + FLASH_BANK_SIZE - BOOT_MAGIC_SZ -\
				  BOOT_MAX_ALIGN)
#define MAGIC_OFFS(bank_offs) (bank_offs + FLASH_BANK_SIZE - BOOT_MAGIC_SZ)

const u32_t boot_img_magic[4] = {
	0xf395c277,
	0x7fefd260,
	0x0f505235,
	0x8079b62c,
};

static struct device *flash_dev;

static int boot_flag_offs(int flag, u32_t bank_offs, u32_t *offs)
{
	switch (flag) {
	case BOOT_FLAG_COPY_DONE:
		*offs = COPY_DONE_OFFS(bank_offs);
		return 0;
	case BOOT_FLAG_IMAGE_OK:
		*offs = IMAGE_OK_OFFS(bank_offs);
		return 0;
	default:
		return -ENOTSUP;
	}
}


static int boot_flash_write(off_t offs, const void *data, size_t len)
{
	int rc;

	rc = flash_write_protection_set(flash_dev, false);
	if (rc) {
		return rc;
	}

	rc = flash_write(flash_dev, offs, data, len);
	if (rc) {
		return rc;
	}

	rc = flash_write_protection_set(flash_dev, true);

	return rc;
}

static int boot_flag_write(int flag, u32_t bank_offs)
{
	u8_t buf[FLASH_MIN_WRITE_SIZE];
	u32_t offs;
	int rc;

	rc = boot_flag_offs(flag, bank_offs, &offs);
	if (rc != 0) {
		return rc;
	}

	memset(buf, BOOT_FLAG_UNSET, sizeof(buf));
	buf[0] = BOOT_FLAG_SET;

	rc = boot_flash_write(offs, buf, sizeof(buf));

	return rc;
}

static int boot_flag_read(int flag, u32_t bank_offs)
{
	u32_t offs;
	int rc;
	u8_t flag_val;

	rc = boot_flag_offs(flag, bank_offs, &offs);
	if (rc != 0) {
		return rc;
	}

	rc = flash_read(flash_dev, offs, &flag_val, sizeof(flag_val));
	if (rc != 0) {
		return rc;
	}

	return flag_val;
}

static int boot_image_ok_read(u32_t bank_offs)
{
	return boot_flag_read(BOOT_FLAG_IMAGE_OK, bank_offs);
}

static int boot_image_ok_write(u32_t bank_offs)
{
	return boot_flag_write(BOOT_FLAG_IMAGE_OK, bank_offs);
}

static int boot_magic_write(u32_t bank_offs)
{
	u32_t offs;
	int rc;

	offs = MAGIC_OFFS(bank_offs);

	rc = boot_flash_write(offs, boot_img_magic, BOOT_MAGIC_SZ);

	return rc;
}

static int boot_read_v1_header(u32_t bank_offset,
			       struct mcuboot_v1_raw_header *v1_raw)
{
	int rc;

	/*
	 * Read and sanity-check the raw header.
	 */
	rc = flash_read(flash_dev, bank_offset, v1_raw, sizeof(*v1_raw));
	if (rc) {
		return rc;
	}

	v1_raw->header_magic = sys_le32_to_cpu(v1_raw->header_magic);
	v1_raw->image_load_address =
		sys_le32_to_cpu(v1_raw->image_load_address);
	v1_raw->header_size = sys_le16_to_cpu(v1_raw->header_size);
	v1_raw->image_size = sys_le32_to_cpu(v1_raw->image_size);
	v1_raw->image_flags = sys_le32_to_cpu(v1_raw->image_flags);
	v1_raw->version.revision =
		sys_le16_to_cpu(v1_raw->version.revision);
	v1_raw->version.build_num =
		sys_le32_to_cpu(v1_raw->version.build_num);

	/*
	 * Sanity checks.
	 *
	 * Larger values in header_size than BOOT_HEADER_SIZE_V1 are
	 * possible, e.g. if Zephyr was linked with
	 * CONFIG_TEXT_SECTION_OFFSET > BOOT_HEADER_SIZE_V1.
	 */
	if ((v1_raw->header_magic != BOOT_HEADER_MAGIC_V1) ||
	    (v1_raw->header_size < BOOT_HEADER_SIZE_V1)) {
		return -EIO;
	}

	return 0;
}

int boot_read_bank_header(u32_t bank_offset,
			  struct mcuboot_img_header *header,
			  size_t header_size)
{
	int rc;
	struct mcuboot_v1_raw_header v1_raw;
	struct mcuboot_img_sem_ver *sem_ver;
	size_t v1_min_size = (sizeof(u32_t) +
			      sizeof(struct mcuboot_img_header_v1));

	/*
	 * Only version 1 image headers are supported.
	 */
	if (header_size < v1_min_size) {
		return -ENOMEM;
	}
	rc = boot_read_v1_header(bank_offset, &v1_raw);
	if (rc) {
		return rc;
	}

	/*
	 * Copy just the fields we care about into the return parameter.
	 *
	 * - header_magic:       skip (only used to check format)
	 * - image_load_address: skip (only matters for PIC code)
	 * - header_size:        skip (only used to check format)
	 * - image_size:         include
	 * - image_flags:        skip (all unsupported or not relevant)
	 * - version:            include
	 */
	header->mcuboot_version = 1;
	header->h.v1.image_size = v1_raw.image_size;
	sem_ver = &header->h.v1.sem_ver;
	sem_ver->major = v1_raw.version.major;
	sem_ver->minor = v1_raw.version.minor;
	sem_ver->revision = v1_raw.version.revision;
	sem_ver->build_num = v1_raw.version.build_num;
	return 0;
}

int boot_request_upgrade(int permanent)
{
	int rc;

	rc = boot_magic_write(FLASH_BANK1_OFFSET);
	if (rc == 0 && permanent) {
		rc = boot_image_ok_write(FLASH_BANK1_OFFSET);
	}

	return rc;
}

bool boot_is_img_confirmed(void)
{
	return boot_image_ok_read(FLASH_BANK0_OFFSET) == BOOT_FLAG_SET;
}

int boot_write_img_confirmed(void)
{
	int rc;

	if (boot_image_ok_read(FLASH_BANK0_OFFSET) != BOOT_FLAG_UNSET) {
		/* Already confirmed. */
		return 0;
	}

	rc = boot_image_ok_write(FLASH_BANK0_OFFSET);

	return rc;
}

int boot_erase_img_bank(u32_t bank_offset)
{
	int rc;

	rc = flash_write_protection_set(flash_dev, false);
	if (rc) {
		return rc;
	}

	rc = flash_erase(flash_dev, bank_offset, FLASH_BANK_SIZE);
	if (rc) {
		return rc;
	}

	rc = flash_write_protection_set(flash_dev, true);

	return rc;
}

static int boot_init(struct device *dev)
{
	ARG_UNUSED(dev);
	flash_dev = device_get_binding(FLASH_DEV_NAME);
	if (!flash_dev) {
		return -ENODEV;
	}
	return 0;
}

SYS_INIT(boot_init, APPLICATION, CONFIG_APPLICATION_INIT_PRIORITY);