main.c

/*
  stm32flash - Open Source ST STM32 flash program for *nix
  Copyright 2010 Geoffrey McRae <geoff@spacevs.com>
  Copyright 2011 Steve Markgraf <steve@steve-m.de>
  Copyright 2012-2016 Tormod Volden <debian.tormod@gmail.com>
  Copyright 2013-2016 Antonio Borneo <borneo.antonio@gmail.com>

  This program is free software; you can redistribute it and/or
  modify it under the terms of the GNU General Public License
  as published by the Free Software Foundation; either version 2
  of the License, or (at your option) any later version.

  This program 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 General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
*/

#include <sys/types.h>
#include <sys/stat.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <signal.h>

#include "init.h"
#include "utils.h"
#include "serial.h"
#include "stm32.h"
#include "parsers/parser.h"
#include "port.h"

#include "parsers/binary.h"
#include "parsers/hex.h"

#if defined(__WIN32__) || defined(__CYGWIN__)
#include <windows.h>
#endif

#define VERSION "STM32duino_0.5.1"

/* device globals */
stm32_t		*stm		= NULL;
void		*p_st		= NULL;
parser_t	*parser		= NULL;
struct port_interface *port = NULL;

/* settings */
struct port_options port_opts = {
	.device			= NULL,
	.baudRate		= SERIAL_BAUD_57600,
	.serial_mode		= "8e1",
	.bus_addr		= 0,
	.rx_frame_max		= STM32_MAX_RX_FRAME,
	.tx_frame_max		= STM32_MAX_TX_FRAME,
};

enum actions {
	ACT_NONE,
	ACT_READ,
	ACT_WRITE,
	ACT_WRITE_UNPROTECT,
	ACT_READ_PROTECT,
	ACT_READ_UNPROTECT,
	ACT_ERASE_ONLY,
	ACT_CRC
};

enum actions	action		= ACT_NONE;
int		npages		= 0;
int             spage           = 0;
int             no_erase        = 0;
char		verify		= 0;
int		retry		= 10;
char		exec_flag	= 0;
uint32_t	execute		= 0;
char		init_flag	= 1;
int		use_stdinout	= 0;
char		force_binary	= 0;
FILE		*diag;
char		reset_flag	= 0;
char		*filename;
char		*gpio_seq	= NULL;
uint32_t	start_addr	= 0;
uint32_t	readwrite_len	= 0;

/* functions */
int  parse_options(int argc, char *argv[]);
void show_help(char *name);

static const char *action2str(enum actions act)
{
	switch (act) {
		case ACT_READ:
			return "memory read";
		case ACT_WRITE:
			return "memory write";
		case ACT_WRITE_UNPROTECT:
			return "write unprotect";
		case ACT_READ_PROTECT:
			return "read protect";
		case ACT_READ_UNPROTECT:
			return "read unprotect";
		case ACT_ERASE_ONLY:
			return "flash erase";
		case ACT_CRC:
			return "memory crc";
		default:
			return "";
	};
}

static void err_multi_action(enum actions new)
{
	fprintf(stderr,
		"ERROR: Invalid options !\n"
		"\tCan't execute \"%s\" and \"%s\" at the same time.\n",
		action2str(action), action2str(new));
}

static int is_addr_in_ram(uint32_t addr)
{
	return addr >= stm->dev->ram_start && addr < stm->dev->ram_end;
}

static int is_addr_in_flash(uint32_t addr)
{
	return addr >= stm->dev->fl_start && addr < stm->dev->fl_end;
}

static int is_addr_in_opt_bytes(uint32_t addr)
{
	/* option bytes upper range is inclusive in our device table */
	return addr >= stm->dev->opt_start && addr <= stm->dev->opt_end;
}

static int is_addr_in_sysmem(uint32_t addr)
{
	return addr >= stm->dev->mem_start && addr < stm->dev->mem_end;
}

/* returns the page that contains address "addr" */
static int flash_addr_to_page_floor(uint32_t addr)
{
	int page;
	uint32_t *psize;

	if (!is_addr_in_flash(addr))
		return 0;

	page = 0;
	addr -= stm->dev->fl_start;
	psize = stm->dev->fl_ps;

	while (addr >= psize[0]) {
		addr -= psize[0];
		page++;
		if (psize[1])
			psize++;
	}

	return page;
}

/* returns the first page whose start addr is >= "addr" */
int flash_addr_to_page_ceil(uint32_t addr)
{
	int page;
	uint32_t *psize;

	if (!(addr >= stm->dev->fl_start && addr <= stm->dev->fl_end))
		return 0;

	page = 0;
	addr -= stm->dev->fl_start;
	psize = stm->dev->fl_ps;

	while (addr >= psize[0]) {
		addr -= psize[0];
		page++;
		if (psize[1])
			psize++;
	}

	return addr ? page + 1 : page;
}

/* returns the lower address of flash page "page" */
static uint32_t flash_page_to_addr(int page)
{
	int i;
	uint32_t addr, *psize;

	addr = stm->dev->fl_start;
	psize = stm->dev->fl_ps;

	for (i = 0; i < page; i++) {
		addr += psize[0];
		if (psize[1])
			psize++;
	}

	return addr;
}


#if defined(__WIN32__) || defined(__CYGWIN__)
BOOL CtrlHandler( DWORD fdwCtrlType )
{
	fprintf(stderr, "\nCaught signal %lu\n",fdwCtrlType);
	if (p_st &&  parser ) parser->close(p_st);
	if (stm  ) stm32_close  (stm);
	if (port) port->close(port);
	exit(1);
}
#else
void sighandler(int s){
	fprintf(stderr, "\nCaught signal %d\n",s);
	if (p_st &&  parser ) parser->close(p_st);
	if (stm  ) stm32_close  (stm);
	if (port) port->close(port);
	exit(1);
}
#endif

int main(int argc, char* argv[]) {
	int ret = 1;
	stm32_err_t s_err;
	parser_err_t perr;
	diag = stdout;

	if (parse_options(argc, argv) != 0)
		goto close;

	if (action == ACT_READ && use_stdinout) {
		diag = stderr;
	}

	fprintf(diag, "stm32flash " VERSION "\n\n");
	fprintf(diag, "https://github.com/stm32duino/stm32flash\n\n");

#if defined(__WIN32__) || defined(__CYGWIN__)
	SetConsoleCtrlHandler( (PHANDLER_ROUTINE) CtrlHandler, TRUE );
#else
	struct sigaction sigIntHandler;

	sigIntHandler.sa_handler = sighandler;
	sigemptyset(&sigIntHandler.sa_mask);
	sigIntHandler.sa_flags = 0;

	sigaction(SIGINT, &sigIntHandler, NULL);
#endif

	if (action == ACT_WRITE) {
		/* first try hex */
		if (!force_binary) {
			parser = &PARSER_HEX;
			p_st = parser->init();
			if (!p_st) {
				fprintf(stderr, "%s Parser failed to initialize\n", parser->name);
				goto close;
			}
		}

		if (force_binary || (perr = parser->open(p_st, filename, 0)) != PARSER_ERR_OK) {
			if (force_binary || perr == PARSER_ERR_INVALID_FILE) {
				if (!force_binary) {
					parser->close(p_st);
					p_st = NULL;
				}

				/* now try binary */
				parser = &PARSER_BINARY;
				p_st = parser->init();
				if (!p_st) {
					fprintf(stderr, "%s Parser failed to initialize\n", parser->name);
					goto close;
				}
				perr = parser->open(p_st, filename, 0);
			}

			/* if still have an error, fail */
			if (perr != PARSER_ERR_OK) {
				fprintf(stderr, "%s ERROR: %s\n", parser->name, parser_errstr(perr));
				if (perr == PARSER_ERR_SYSTEM) perror(filename);
				goto close;
			}
		}

		fprintf(diag, "Using Parser : %s\n", parser->name);
	} else {
		parser = &PARSER_BINARY;
		p_st = parser->init();
		if (!p_st) {
			fprintf(stderr, "%s Parser failed to initialize\n", parser->name);
			goto close;
		}
	}

	if (port_open(&port_opts, &port) != PORT_ERR_OK) {
		fprintf(stderr, "Failed to open port: %s\n", port_opts.device);
		goto close;
	}

	fprintf(diag, "Interface %s: %s\n", port->name, port->get_cfg_str(port));
	if (init_flag && init_bl_entry(port, gpio_seq)){
		ret = 1;
		fprintf(stderr, "Failed to send boot enter sequence\n");
		goto close;
	}

	port->flush(port);

	stm = stm32_init(port, init_flag);
	if (!stm)
		goto close;

	fprintf(diag, "Version      : 0x%02x\n", stm->bl_version);
	if (port->flags & PORT_GVR_ETX) {
		fprintf(diag, "Option 1     : 0x%02x\n", stm->option1);
		fprintf(diag, "Option 2     : 0x%02x\n", stm->option2);
	}
	fprintf(diag, "Device ID    : 0x%04x (%s)\n", stm->pid, stm->dev->name);
	fprintf(diag, "- RAM        : Up to %dKiB  (%db reserved by bootloader)\n", (stm->dev->ram_end - 0x20000000) / 1024, stm->dev->ram_start - 0x20000000);
	fprintf(diag, "- Flash      : Up to %dKiB (size first sector: %dx%d)\n", (stm->dev->fl_end - stm->dev->fl_start ) / 1024, stm->dev->fl_pps, stm->dev->fl_ps[0]);
	fprintf(diag, "- Option RAM : %db\n", stm->dev->opt_end - stm->dev->opt_start + 1);
	fprintf(diag, "- System RAM : %dKiB\n", (stm->dev->mem_end - stm->dev->mem_start) / 1024);

	uint8_t		buffer[256];
	uint32_t	addr, start, end;
	unsigned int	len;
	int		failed = 0;
	int		first_page, num_pages;

	/*
	 * Cleanup addresses:
	 *
	 * Starting from options
	 *	start_addr, readwrite_len, spage, npages
	 * and using device memory size, compute
	 *	start, end, first_page, num_pages
	 */
	if (start_addr || readwrite_len) {
		start = start_addr;

		if (is_addr_in_flash(start))
			end = stm->dev->fl_end;
		else {
			no_erase = 1;
			if (is_addr_in_ram(start))
				end = stm->dev->ram_end;
			else if (is_addr_in_opt_bytes(start))
				end = stm->dev->opt_end + 1;
			else if (is_addr_in_sysmem(start))
				end = stm->dev->mem_end;
			else {
				/* Unknown territory */
				if (readwrite_len)
					end = start + readwrite_len;
				else
					end = start + sizeof(uint32_t);
			}
		}

		if (readwrite_len && (end > start + readwrite_len))
			end = start + readwrite_len;

		first_page = flash_addr_to_page_floor(start);
		if (!first_page && end == stm->dev->fl_end)
			num_pages = STM32_MASS_ERASE;
		else
			num_pages = flash_addr_to_page_ceil(end) - first_page;
	} else if (!spage && !npages) {
		start = stm->dev->fl_start;
		end = stm->dev->fl_end;
		first_page = 0;
		num_pages = STM32_MASS_ERASE;
	} else {
		first_page = spage;
		start = flash_page_to_addr(first_page);
		if (start > stm->dev->fl_end) {
			fprintf(stderr, "Address range exceeds flash size.\n");
			goto close;
		}

		if (npages) {
			num_pages = npages;
			end = flash_page_to_addr(first_page + num_pages);
			if (end > stm->dev->fl_end)
				end = stm->dev->fl_end;
		} else {
			end = stm->dev->fl_end;
			num_pages = flash_addr_to_page_ceil(end) - first_page;
		}

		if (!first_page && end == stm->dev->fl_end)
			num_pages = STM32_MASS_ERASE;
	}

	if (action == ACT_READ) {
		unsigned int max_len = port_opts.rx_frame_max;

		fprintf(diag, "Memory read\n");

		perr = parser->open(p_st, filename, 1);
		if (perr != PARSER_ERR_OK) {
			fprintf(stderr, "%s ERROR: %s\n", parser->name, parser_errstr(perr));
			if (perr == PARSER_ERR_SYSTEM)
				perror(filename);
			goto close;
		}

		fflush(diag);
		addr = start;
		while(addr < end) {
			uint32_t left	= end - addr;
			len		= max_len > left ? left : max_len;
			s_err = stm32_read_memory(stm, addr, buffer, len);
			if (s_err != STM32_ERR_OK) {
				fprintf(stderr, "Failed to read memory at address 0x%08x, target write-protected?\n", addr);
				goto close;
			}
			if (parser->write(p_st, buffer, len) != PARSER_ERR_OK)
			{
				fprintf(stderr, "Failed to write data to file\n");
				goto close;
			}
			addr += len;

			fprintf(diag,
				"\rRead address 0x%08x (%.2f%%) ",
				addr,
				(100.0f / (float)(end - start)) * (float)(addr - start)
			);
			fflush(diag);
		}
		fprintf(diag,	"Done.\n");
		ret = 0;
		goto close;
	} else if (action == ACT_READ_PROTECT) {
		fprintf(diag, "Read-Protecting flash\n");
		/* the device automatically performs a reset after the sending the ACK */
		reset_flag = 0;
		s_err = stm32_readprot_memory(stm);
		if (s_err != STM32_ERR_OK) {
			fprintf(stderr, "Failed to read-protect flash\n");
			goto close;
		}
		fprintf(diag,	"Done.\n");
		ret = 0;
	} else if (action == ACT_READ_UNPROTECT) {
		fprintf(diag, "Read-UnProtecting flash\n");
		/* the device automatically performs a reset after the sending the ACK */
		reset_flag = 0;
		s_err = stm32_runprot_memory(stm);
		if (s_err != STM32_ERR_OK) {
			fprintf(stderr, "Failed to read-unprotect flash\n");
			goto close;
		}
		fprintf(diag,	"Done.\n");
		ret = 0;
	} else if (action == ACT_ERASE_ONLY) {
		ret = 0;
		fprintf(diag, "Erasing flash\n");

		if (num_pages != STM32_MASS_ERASE &&
		    (start != flash_page_to_addr(first_page)
		     || end != flash_page_to_addr(first_page + num_pages))) {
			fprintf(stderr, "Specified start & length are invalid (must be page aligned)\n");
			ret = 1;
			goto close;
		}

		s_err = stm32_erase_memory(stm, first_page, num_pages);
		if (s_err != STM32_ERR_OK) {
			fprintf(stderr, "Failed to erase memory\n");
			ret = 1;
			goto close;
		}
		ret = 0;
	} else if (action == ACT_WRITE_UNPROTECT) {
		fprintf(diag, "Write-unprotecting flash\n");
		/* the device automatically performs a reset after the sending the ACK */
		reset_flag = 0;
		s_err = stm32_wunprot_memory(stm);
		if (s_err != STM32_ERR_OK) {
			fprintf(stderr, "Failed to write-unprotect flash\n");
			goto close;
		}
		fprintf(diag,	"Done.\n");
		ret = 0;
	} else if (action == ACT_WRITE) {
		fprintf(diag, "Write to memory\n");

		unsigned int offset = 0;
		unsigned int r;
		unsigned int size;
		unsigned int max_wlen, max_rlen;

		max_wlen = port_opts.tx_frame_max - 2;	/* skip len and crc */
		max_wlen &= ~3;	/* 32 bit aligned */

		max_rlen = port_opts.rx_frame_max;
		max_rlen = max_rlen < max_wlen ? max_rlen : max_wlen;

		/* Assume data from stdin is whole device */
		if (use_stdinout)
			size = end - start;
		else
			size = parser->size(p_st);

		// TODO: It is possible to write to non-page boundaries, by reading out flash
		//       from partial pages and combining with the input data
		// if ((start % stm->dev->fl_ps[i]) != 0 || (end % stm->dev->fl_ps[i]) != 0) {
		//	fprintf(stderr, "Specified start & length are invalid (must be page aligned)\n");
		//	goto close;
		// }

		// TODO: If writes are not page aligned, we should probably read out existing flash
		//       contents first, so it can be preserved and combined with new data
		if (!no_erase && num_pages) {
			fprintf(diag, "Erasing memory\n");
			s_err = stm32_erase_memory(stm, first_page, num_pages);
			if (s_err != STM32_ERR_OK) {
				fprintf(stderr, "Failed to erase memory\n");
				goto close;
			}
		}

		fflush(diag);
		addr = start;
		while(addr < end && offset < size) {
			uint32_t left	= end - addr;
			len		= max_wlen > left ? left : max_wlen;
			len		= len > size - offset ? size - offset : len;

			if (parser->read(p_st, buffer, &len) != PARSER_ERR_OK)
				goto close;

			if (len == 0) {
				if (use_stdinout) {
					break;
				} else {
					fprintf(stderr, "Failed to read input file\n");
					goto close;
				}
			}

			again:
			s_err = stm32_write_memory(stm, addr, buffer, len);
			if (s_err != STM32_ERR_OK) {
				fprintf(stderr, "Failed to write memory at address 0x%08x\n", addr);
				goto close;
			}

			if (verify) {
				uint8_t compare[len];
				unsigned int offset, rlen;

				offset = 0;
				while (offset < len) {
					rlen = len - offset;
					rlen = rlen < max_rlen ? rlen : max_rlen;
					s_err = stm32_read_memory(stm, addr + offset, compare + offset, rlen);
					if (s_err != STM32_ERR_OK) {
						fprintf(stderr, "Failed to read memory at address 0x%08x\n", addr + offset);
						goto close;
					}
					offset += rlen;
				}

				for(r = 0; r < len; ++r)
					if (buffer[r] != compare[r]) {
						if (failed == retry) {
							fprintf(stderr, "Failed to verify at address 0x%08x, expected 0x%02x and found 0x%02x\n",
								(uint32_t)(addr + r),
								buffer [r],
								compare[r]
							);
							goto close;
						}
						++failed;
						goto again;
					}

				failed = 0;
			}

			addr	+= len;
			offset	+= len;

			fprintf(diag,
				"\rWrote %saddress 0x%08x (%.2f%%) ",
				verify ? "and verified " : "",
				addr,
				(100.0f / size) * offset
			);
			fflush(diag);

		}

		fprintf(diag,	"Done.\n");
		ret = 0;
		goto close;
	} else if (action == ACT_CRC) {
		uint32_t crc_val = 0;

		fprintf(diag, "CRC computation\n");

		s_err = stm32_crc_wrapper(stm, start, end - start, &crc_val);
		if (s_err != STM32_ERR_OK) {
			fprintf(stderr, "Failed to read CRC\n");
			goto close;
		}
		fprintf(diag, "CRC(0x%08x-0x%08x) = 0x%08x\n", start, end,
			crc_val);
		ret = 0;
		goto close;
	} else
		ret = 0;

close:
	if (stm && exec_flag && ret == 0) {
		if (execute == 0)
			execute = stm->dev->fl_start;

		fprintf(diag, "\nStarting execution at address 0x%08x... ", execute);
		fflush(diag);
		if (stm32_go(stm, execute) == STM32_ERR_OK) {
			reset_flag = 0;
			fprintf(diag, "done.\n");
		} else
			fprintf(diag, "failed.\n");
	}

	if (stm && reset_flag) {
		fprintf(diag, "\nResetting device... \n");
		fflush(diag);
		if (init_bl_exit(stm, port, gpio_seq)) {
			ret = 1;
			fprintf(diag, "Reset failed.\n");
		} else
			fprintf(diag, "Reset done.\n");
	} else if (port) {
		/* Always run exit sequence if present */
		if (gpio_seq && strchr(gpio_seq, ':'))
			ret = gpio_bl_exit(port, gpio_seq) || ret;
	}

	if (p_st  ) parser->close(p_st);
	if (stm   ) stm32_close  (stm);
	if (port)
		port->close(port);

	fprintf(diag, "\n");
	return ret;
}

int parse_options(int argc, char *argv[])
{
	int c;
	char *pLen;

	while ((c = getopt(argc, argv, "a:b:m:r:w:e:vn:g:jkfcChuos:S:F:i:R")) != -1) {
		switch(c) {
			case 'a':
				port_opts.bus_addr = strtoul(optarg, NULL, 0);
				break;

			case 'b':
				port_opts.baudRate = serial_get_baud(strtoul(optarg, NULL, 0));
				if (port_opts.baudRate == SERIAL_BAUD_INVALID) {
					serial_baud_t baudrate;
					fprintf(stderr,	"Invalid baud rate, valid options are:\n");
					for (baudrate = SERIAL_BAUD_1200; baudrate != SERIAL_BAUD_INVALID; ++baudrate)
						fprintf(stderr, " %d\n", serial_get_baud_int(baudrate));
					return 1;
				}
				break;

			case 'm':
				if (strlen(optarg) != 3
					|| serial_get_bits(optarg) == SERIAL_BITS_INVALID
					|| serial_get_parity(optarg) == SERIAL_PARITY_INVALID
					|| serial_get_stopbit(optarg) == SERIAL_STOPBIT_INVALID) {
					fprintf(stderr, "Invalid serial mode\n");
					return 1;
				}
				port_opts.serial_mode = optarg;
				break;

			case 'r':
			case 'w':
				if (action != ACT_NONE) {
					err_multi_action((c == 'r') ? ACT_READ : ACT_WRITE);
					return 1;
				}
				action = (c == 'r') ? ACT_READ : ACT_WRITE;
				filename = optarg;
				if (filename[0] == '-' && filename[1] == '\0') {
					use_stdinout = 1;
					force_binary = 1;
				}
				break;
			case 'e':
				if (readwrite_len || start_addr) {
					fprintf(stderr, "ERROR: Invalid options, can't specify start page / num pages and start address/length\n");
					return 1;
				}
				npages = strtoul(optarg, NULL, 0);
				if (npages > STM32_MAX_PAGES || npages < 0) {
					fprintf(stderr, "ERROR: You need to specify a page count between 0 and 255");
					return 1;
				}
				if (!npages)
					no_erase = 1;
				break;
			case 'u':
				if (action != ACT_NONE) {
					err_multi_action(ACT_WRITE_UNPROTECT);
					return 1;
				}
				action = ACT_WRITE_UNPROTECT;
				break;

			case 'j':
				if (action != ACT_NONE) {
					err_multi_action(ACT_READ_PROTECT);
					return 1;
				}
				action = ACT_READ_PROTECT;
				break;

			case 'k':
				if (action != ACT_NONE) {
					err_multi_action(ACT_READ_UNPROTECT);
					return 1;
				}
				action = ACT_READ_UNPROTECT;
				break;

			case 'o':
				if (action != ACT_NONE) {
					err_multi_action(ACT_ERASE_ONLY);
					return 1;
				}
				action = ACT_ERASE_ONLY;
				break;

			case 'v':
				verify = 1;
				break;

			case 'n':
				retry = strtoul(optarg, NULL, 0);
				break;

			case 'g':
				exec_flag = 1;
				execute   = strtoul(optarg, NULL, 0);
				if (execute % 4 != 0) {
					fprintf(stderr, "ERROR: Execution address must be word-aligned\n");
					return 1;
				}
				break;
			case 's':
				if (readwrite_len || start_addr) {
					fprintf(stderr, "ERROR: Invalid options, can't specify start page / num pages and start address/length\n");
					return 1;
				}
				spage    = strtoul(optarg, NULL, 0);
				break;
			case 'S':
				if (spage || npages) {
					fprintf(stderr, "ERROR: Invalid options, can't specify start page / num pages and start address/length\n");
					return 1;
				} else {
					start_addr = strtoul(optarg, &pLen, 0);
					if (*pLen == ':') {
						pLen++;
						readwrite_len = strtoul(pLen, NULL, 0);
						if (readwrite_len == 0) {
							fprintf(stderr, "ERROR: Invalid options, can't specify zero length\n");
							return 1;
						}
					}
				}
				break;
			case 'F':
				port_opts.rx_frame_max = strtoul(optarg, &pLen, 0);
				if (*pLen == ':') {
					pLen++;
					port_opts.tx_frame_max = strtoul(pLen, NULL, 0);
				}
				if (port_opts.rx_frame_max < 0
				    || port_opts.tx_frame_max < 0) {
					fprintf(stderr, "ERROR: Invalid negative value for option -F\n");
					return 1;
				}
				if (port_opts.rx_frame_max == 0)
					port_opts.rx_frame_max = STM32_MAX_RX_FRAME;
				if (port_opts.tx_frame_max == 0)
					port_opts.tx_frame_max = STM32_MAX_TX_FRAME;
				if (port_opts.rx_frame_max < 20
				    || port_opts.tx_frame_max < 6) {
					fprintf(stderr, "ERROR: current code cannot work with small frames.\n");
					fprintf(stderr, "min(RX) = 20, min(TX) = 6\n");
					return 1;
				}
				if (port_opts.rx_frame_max > STM32_MAX_RX_FRAME) {
					fprintf(stderr, "WARNING: Ignore RX length in option -F\n");
					port_opts.rx_frame_max = STM32_MAX_RX_FRAME;
				}
				if (port_opts.tx_frame_max > STM32_MAX_TX_FRAME) {
					fprintf(stderr, "WARNING: Ignore TX length in option -F\n");
					port_opts.tx_frame_max = STM32_MAX_TX_FRAME;
				}
				break;
			case 'f':
				force_binary = 1;
				break;

			case 'c':
				init_flag = 0;
				break;

			case 'h':
				show_help(argv[0]);
				exit(0);

			case 'i':
				gpio_seq = optarg;
				break;

			case 'R':
				reset_flag = 1;
				break;

			case 'C':
				if (action != ACT_NONE) {
					err_multi_action(ACT_CRC);
					return 1;
				}
				action = ACT_CRC;
				break;
		}
	}

	for (c = optind; c < argc; ++c) {
		if (port_opts.device) {
			fprintf(stderr, "ERROR: Invalid parameter specified\n");
			show_help(argv[0]);
			return 1;
		}
		port_opts.device = argv[c];
	}

	if (port_opts.device == NULL) {
		fprintf(stderr, "ERROR: Device not specified\n");
		show_help(argv[0]);
		return 1;
	}

	if ((action != ACT_WRITE) && verify) {
		fprintf(stderr, "ERROR: Invalid usage, -v is only valid when writing\n");
		show_help(argv[0]);
		return 1;
	}

	return 0;
}

void show_help(char *name) {
	fprintf(stderr,
		"Usage: %s [-bvngfhc] [-[rw] filename] [tty_device | i2c_device]\n"
		"	-a bus_address	Bus address (e.g. for I2C port)\n"
		"	-b rate		Baud rate (default 57600)\n"
		"	-m mode		Serial port mode (default 8e1)\n"
		"	-r filename	Read flash to file (or - stdout)\n"
		"	-w filename	Write flash from file (or - stdout)\n"
		"	-C		Compute CRC of flash content\n"
		"	-u		Disable the flash write-protection\n"
		"	-j		Enable the flash read-protection\n"
		"	-k		Disable the flash read-protection\n"
		"	-o		Erase only\n"
		"	-e n		Only erase n pages before writing the flash\n"
		"	-v		Verify writes\n"
		"	-n count	Retry failed writes up to count times (default 10)\n"
		"	-g address	Start execution at specified address (0 = flash start)\n"
		"	-S address[:length]	Specify start address and optionally length for\n"
		"	                   	read/write/erase operations\n"
		"	-F RX_length[:TX_length]  Specify the max length of RX and TX frame\n"
		"	-s start_page	Flash at specified page (0 = flash start)\n"
		"	-f		Force binary parser\n"
		"	-h		Show this help\n"
		"	-c		Resume the connection (don't send initial INIT)\n"
		"			*Baud rate must be kept the same as the first init*\n"
		"			This is useful if the reset fails\n"
		"	-R		Reset device at exit.\n"
		"	-i GPIO_string	GPIO sequence to enter/exit bootloader mode\n"
		"			GPIO_string=[entry_seq][:[exit_seq]]\n"
		"			sequence=[[-]signal]&|,[sequence]\n"
		"\n"
		"GPIO sequence:\n"
		"	The following signals can appear in a sequence:\n"
		"	  Integer number representing GPIO pin\n"
		"	  'dtr', 'rts' or 'brk' representing serial port signal\n"
		"	The sequence can use the following delimiters:\n"
		"	  ',' adds 100 ms delay between signals\n"
		"	  '&' adds no delay between signals\n"
		"	The following modifiers can be prepended to a signal:\n"
		"	  '-' reset signal (low) instead of setting it (high)\n"
		"\n"
		"Examples:\n"
		"	Get device information:\n"
		"		%s /dev/ttyS0\n"
		"	  or:\n"
		"		%s /dev/i2c-0\n"
		"\n"
		"	Write with verify and then start execution:\n"
		"		%s -w filename -v -g 0x0 /dev/ttyS0\n"
		"\n"
		"	Read flash to file:\n"
		"		%s -r filename /dev/ttyS0\n"
		"\n"
		"	Read 100 bytes of flash from 0x1000 to stdout:\n"
		"		%s -r - -S 0x1000:100 /dev/ttyS0\n"
		"\n"
		"	Start execution:\n"
		"		%s -g 0x0 /dev/ttyS0\n"
		"\n"
		"	GPIO sequence:\n"
		"	- entry sequence: GPIO_3=low, GPIO_2=low, 100ms delay, GPIO_2=high\n"
		"	- exit sequence: GPIO_3=high, GPIO_2=low, 300ms delay, GPIO_2=high\n"
		"		%s -i '-3&-2,2:3&-2,,,2' /dev/ttyS0\n"
		"	GPIO sequence adding delay after port opening:\n"
		"	- entry sequence: delay 500ms\n"
		"	- exit sequence: rts=high, dtr=low, 300ms delay, GPIO_2=high\n"
		"		%s -R -i ',,,,,:rts&-dtr,,,2' /dev/ttyS0\n",
		name,
		name,
		name,
		name,
		name,
		name,
		name,
		name,
		name
	);
}