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 * 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.
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 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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/**
 * @file bl_update.c
 *
 * STM32F4 bootloader update tool.
 */

#include <nuttx/config.h>

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/stat.h>

#include <arch/board/board.h>

#include "systemlib/systemlib.h"
#include "systemlib/err.h"

#define BL_FILE_SIZE_LIMIT	16384

__EXPORT int bl_update_main(int argc, char *argv[]);

static void setopt(void);

int
bl_update_main(int argc, char *argv[])
{
	if (argc != 2)
		errx(1, "missing firmware filename or command");

	if (!strcmp(argv[1], "setopt"))
		setopt();

	int fd = open(argv[1], O_RDONLY);

	if (fd < 0)
		err(1, "open %s", argv[1]);

	struct stat s;

	if (stat(argv[1], &s) != 0)
		err(1, "stat %s", argv[1]);

	/* sanity-check file size */
	if (s.st_size > BL_FILE_SIZE_LIMIT)
		errx(1, "%s: file too large (limit: %u, actual: %d)", argv[1], BL_FILE_SIZE_LIMIT, s.st_size);

	uint8_t *buf = malloc(s.st_size);

	if (buf == NULL)
		errx(1, "failed to allocate %u bytes for firmware buffer", s.st_size);

	if (read(fd, buf, s.st_size) != s.st_size)
		err(1, "firmware read error");

	close(fd);

	uint32_t *hdr = (uint32_t *)buf;

	if ((hdr[0] < 0x20000000) ||			/* stack not below RAM */
	    (hdr[0] > (0x20000000 + (128 * 1024))) ||	/* stack not above RAM */
	    (hdr[1] < 0x08000000) ||			/* entrypoint not below flash */
	    ((hdr[1] - 0x08000000) > 16384)) {		/* entrypoint not outside bootloader */
		free(buf);
		errx(1, "not a bootloader image");
	}

	warnx("image validated, erasing bootloader...");
	usleep(10000);

	/* prevent other tasks from running while we do this */
	sched_lock();

	/* unlock the control register */
	volatile uint32_t *keyr = (volatile uint32_t *)0x40023c04;
	*keyr = 0x45670123U;
	*keyr = 0xcdef89abU;

	volatile uint32_t *sr = (volatile uint32_t *)0x40023c0c;
	volatile uint32_t *cr = (volatile uint32_t *)0x40023c10;
	volatile uint8_t *base = (volatile uint8_t *)0x08000000;

	/* check the control register */
	if (*cr & 0x80000000) {
		warnx("WARNING: flash unlock failed, flash aborted");
		goto flash_end;
	}

	/* erase the bootloader sector */
	*cr = 0x2;
	*cr = 0x10002;

	/* wait for the operation to complete */
	while (*sr & 0x1000) {
	}

	if (*sr & 0xf2) {
		warnx("WARNING: erase error 0x%02x", *sr);
		goto flash_end;
	}

	/* verify the erase */
	for (int i = 0; i < s.st_size; i++) {
		if (base[i] != 0xff) {
			warnx("WARNING: erase failed at %d - retry update, DO NOT reboot", i);
			goto flash_end;
		}
	}

	warnx("flashing...");

	/* now program the bootloader - speed is not critical so use x8 mode */
	for (int i = 0; i < s.st_size; i++) {

		/* program a byte */
		*cr = 1;
		base[i] = buf[i];

		/* wait for the operation to complete */
		while (*sr & 0x1000) {
		}

		if (*sr & 0xf2) {
			warnx("WARNING: program error 0x%02x", *sr);
			goto flash_end;
		}
	}

	/* re-lock the flash control register */
	*cr = 0x80000000;

	warnx("verifying...");

	/* now run a verify pass */
	for (int i = 0; i < s.st_size; i++) {
		if (base[i] != buf[i]) {
			warnx("WARNING: verify failed at %u - retry update, DO NOT reboot", i);
			goto flash_end;
		}
	}

	warnx("bootloader update complete");

flash_end:
	/* unlock the scheduler */
	sched_unlock();

	free(buf);
	exit(0);
}

static void
setopt(void)
{
	volatile uint32_t *optcr = (volatile uint32_t *)0x40023c14;

	const uint16_t opt_mask = (3 << 2);		/* BOR_LEV bitmask */
	const uint16_t opt_bits = (0 << 2);		/* BOR = 0, setting for 2.7-3.6V operation */

	if ((*optcr & opt_mask) == opt_bits)
		errx(0, "option bits are already set as required");

	/* unlock the control register */
	volatile uint32_t *optkeyr = (volatile uint32_t *)0x40023c08;
	*optkeyr = 0x08192a3bU;
	*optkeyr = 0x4c5d6e7fU;

	if (*optcr & 1)
		errx(1, "option control register unlock failed");

	/* program the new option value */
	*optcr = (*optcr & ~opt_mask) | opt_bits | (1 << 1);

	usleep(1000);

	if ((*optcr & opt_mask) == opt_bits)
		errx(0, "option bits set");

	errx(1, "option bits setting failed; readback 0x%04x", *optcr);

}