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avrdude/src/linuxgpio.c

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/*
* avrdude - A Downloader/Uploader for AVR device programmers
* Support for bitbanging GPIO pins using the /sys/class/gpio interface
*
* Copyright (C) 2013 Radoslav Kolev <radoslav@kolev.info>
*
* 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include "ac_cfg.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <sys/stat.h>
#include "avrdude.h"
#include "libavrdude.h"
#include "bitbang.h"
#if HAVE_LINUXGPIO
/*
* GPIO user space helpers
*
* Copyright 2009 Analog Devices Inc.
* Michael Hennerich (hennerich@blackfin.uclinux.org)
*
* Licensed under the GPL-2 or later
*/
/*
* GPIO user space helpers
* The following functions are acting on an "unsigned gpio" argument, which corresponds to the
* gpio numbering scheme in the kernel (starting from 0).
*/
#define GPIO_DIR_IN 0
#define GPIO_DIR_OUT 1
static int linuxgpio_export(unsigned int gpio)
{
int fd, len, r;
char buf[11];
fd = open("/sys/class/gpio/export", O_WRONLY);
if (fd < 0) {
pmsg_ext_error("cannot open /sys/class/gpio/export: %s\n", strerror(errno));
return fd;
}
len = snprintf(buf, sizeof(buf), "%u", gpio);
r = write(fd, buf, len);
close(fd);
return r;
}
static int linuxgpio_unexport(unsigned int gpio)
{
int fd, len, r;
char buf[11];
fd = open("/sys/class/gpio/unexport", O_WRONLY);
if (fd < 0) {
pmsg_ext_error("cannot open /sys/class/gpio/unexport: %s\n", strerror(errno));
return fd;
}
len = snprintf(buf, sizeof(buf), "%u", gpio);
r = write(fd, buf, len);
close(fd);
return r;
}
static int linuxgpio_openfd(unsigned int gpio)
{
char filepath[60];
snprintf(filepath, sizeof(filepath), "/sys/class/gpio/gpio%u/value", gpio);
return (open(filepath, O_RDWR));
}
static int linuxgpio_dir(unsigned int gpio, unsigned int dir)
{
int fd, r;
char buf[60];
snprintf(buf, sizeof(buf), "/sys/class/gpio/gpio%u/direction", gpio);
fd = open(buf, O_WRONLY);
if (fd < 0) {
pmsg_ext_error("cannot open %s: %s\n", buf, strerror(errno));
return fd;
}
if (dir == GPIO_DIR_OUT)
r = write(fd, "out", 4);
else
r = write(fd, "in", 3);
close(fd);
return r;
}
static int linuxgpio_dir_out(unsigned int gpio)
{
return linuxgpio_dir(gpio, GPIO_DIR_OUT);
}
static int linuxgpio_dir_in(unsigned int gpio)
{
return linuxgpio_dir(gpio, GPIO_DIR_IN);
}
/*
* End of GPIO user space helpers
*/
#define N_GPIO (PIN_MAX + 1)
/* Delay between checks for successful GPIO export (100ms) */
#define GPIO_SYSFS_OPEN_DELAY 100000
/* Number of retries to check for successful GPIO exports */
#define GPIO_SYSFS_OPEN_RETRIES 10
/*
* an array which holds open FDs to /sys/class/gpio/gpioXX/value for all needed pins
*/
static int linuxgpio_fds[N_GPIO] ;
static int linuxgpio_setpin(const PROGRAMMER *pgm, int pinfunc, int value) {
if(pinfunc < 0 || pinfunc >= N_PINS)
return -1;
unsigned pin = pgm->pinno[pinfunc];
if (pin & PIN_INVERSE)
value = !value;
pin &= PIN_MASK;
if (pin > PIN_MAX || linuxgpio_fds[pin] < 0)
return -1;
if (write(linuxgpio_fds[pin], value? "1": "0", 1) != 1)
return -1;
if (pgm->ispdelay > 1)
bitbang_delay(pgm->ispdelay);
return 0;
}
static int linuxgpio_getpin(const PROGRAMMER *pgm, int pinfunc) {
if(pinfunc < 0 || pinfunc >= N_PINS)
return -1;
unsigned int pin = pgm->pinno[pinfunc];
int invert = !!(pin & PIN_INVERSE);
pin &= PIN_MASK;
if(pin > PIN_MAX || linuxgpio_fds[pin] < 0)
return -1;
if(lseek(linuxgpio_fds[pin], 0, SEEK_SET) < 0)
return -1;
char c;
if(read(linuxgpio_fds[pin], &c, 1) != 1)
return -1;
return c=='0'? 0+invert: c=='1'? 1-invert: -1;
}
static int linuxgpio_highpulsepin(const PROGRAMMER *pgm, int pinfunc) {
if(pinfunc < 0 || pinfunc >= N_PINS)
return -1;
unsigned int pin = pgm->pinno[pinfunc] & PIN_MASK;
if (pin > PIN_MAX || linuxgpio_fds[pin] < 0 )
return -1;
linuxgpio_setpin(pgm, pinfunc, 1);
linuxgpio_setpin(pgm, pinfunc, 0);
return 0;
}
static void linuxgpio_display(const PROGRAMMER *pgm, const char *p) {
msg_info("%sPin assignment : /sys/class/gpio/gpio{n}\n",p);
pgm_display_generic_mask(pgm, p, SHOW_AVR_PINS);
}
static void linuxgpio_enable(PROGRAMMER *pgm, const AVRPART *p) {
/* nothing */
}
static void linuxgpio_disable(const PROGRAMMER *pgm) {
/* nothing */
}
static void linuxgpio_powerup(const PROGRAMMER *pgm) {
/* nothing */
}
static void linuxgpio_powerdown(const PROGRAMMER *pgm) {
/* nothing */
}
static int linuxgpio_open(PROGRAMMER *pgm, const char *port) {
int r, i, pin;
char gpio_path[60];
struct stat stat_buf;
if (bitbang_check_prerequisites(pgm) < 0)
return -1;
for (i=0; i<N_GPIO; i++)
linuxgpio_fds[i] = -1;
// Avrdude assumes that if a pin number is invalid it means not used/available
for (i = 1; i < N_PINS; i++) { // The pin enumeration in libavrdude.h starts with PPI_AVR_VCC = 1
if ((pgm->pinno[i] & PIN_MASK) <= PIN_MAX) {
pin = pgm->pinno[i] & PIN_MASK;
if ((r=linuxgpio_export(pin)) < 0) {
pmsg_ext_error("cannot export GPIO %d, already exported/busy?: %s",
pin, strerror(errno));
return r;
}
/* Wait until GPIO directory appears */
snprintf(gpio_path, sizeof(gpio_path), "/sys/class/gpio/gpio%u", pin);
unsigned int retry_count;
for (retry_count = 0; retry_count < GPIO_SYSFS_OPEN_RETRIES; retry_count++) {
int ret = stat(gpio_path, &stat_buf);
if (ret == 0) {
break;
} else if (ret < 0 && errno != ENOENT) {
linuxgpio_unexport(pin);
return ret;
}
usleep(GPIO_SYSFS_OPEN_DELAY);
}
/* Write direction, looping in case of EACCES errors due to delayed
* udev permission rule application after export */
for (retry_count = 0; retry_count < GPIO_SYSFS_OPEN_RETRIES; retry_count++) {
usleep(GPIO_SYSFS_OPEN_DELAY);
if (i == PIN_AVR_SDI)
r=linuxgpio_dir_in(pin);
else
r=linuxgpio_dir_out(pin);
if (r >= 0)
break;
if (errno != EACCES) {
linuxgpio_unexport(pin);
return r;
}
}
if (retry_count)
pmsg_notice2("needed %d retr%s for linuxgpio_dir_%s(%s)\n",
retry_count, retry_count > 1? "ies": "y",
i == PIN_AVR_SDI? "in": "out", avr_pin_name(pin));
if (r < 0) {
linuxgpio_unexport(pin);
return r;
}
if ((linuxgpio_fds[pin]=linuxgpio_openfd(pin)) < 0)
return linuxgpio_fds[pin];
}
}
return(0);
}
static void linuxgpio_close(PROGRAMMER *pgm)
{
int i, reset_pin;
reset_pin = pgm->pinno[PIN_AVR_RESET] & PIN_MASK;
//first configure all pins as input, except RESET
//this should avoid possible conflicts when AVR firmware starts
for (i=0; i<N_GPIO; i++) {
if (linuxgpio_fds[i] >= 0 && i != reset_pin) {
close(linuxgpio_fds[i]);
linuxgpio_fds[i] = -1;
linuxgpio_dir_in(i);
linuxgpio_unexport(i);
}
}
//configure RESET as input, if there's external pull up it will go high
if(reset_pin <= PIN_MAX && linuxgpio_fds[reset_pin] >= 0) {
close(linuxgpio_fds[reset_pin]);
linuxgpio_fds[reset_pin] = -1;
linuxgpio_dir_in(reset_pin);
linuxgpio_unexport(reset_pin);
}
}
void linuxgpio_initpgm(PROGRAMMER *pgm) {
strcpy(pgm->type, "linuxgpio");
pgm_fill_old_pins(pgm); // TODO to be removed if old pin data no longer needed
pgm->rdy_led = bitbang_rdy_led;
pgm->err_led = bitbang_err_led;
pgm->pgm_led = bitbang_pgm_led;
pgm->vfy_led = bitbang_vfy_led;
pgm->initialize = bitbang_initialize;
pgm->display = linuxgpio_display;
pgm->enable = linuxgpio_enable;
pgm->disable = linuxgpio_disable;
pgm->powerup = linuxgpio_powerup;
pgm->powerdown = linuxgpio_powerdown;
pgm->program_enable = bitbang_program_enable;
pgm->chip_erase = bitbang_chip_erase;
pgm->cmd = bitbang_cmd;
pgm->cmd_tpi = bitbang_cmd_tpi;
pgm->open = linuxgpio_open;
pgm->close = linuxgpio_close;
pgm->setpin = linuxgpio_setpin;
pgm->getpin = linuxgpio_getpin;
pgm->highpulsepin = linuxgpio_highpulsepin;
pgm->read_byte = avr_read_byte_default;
pgm->write_byte = avr_write_byte_default;
}
const char linuxgpio_desc[] = "GPIO bitbanging using the Linux sysfs interface";
#else /* !HAVE_LINUXGPIO */
void linuxgpio_initpgm(PROGRAMMER *pgm) {
pmsg_error("Linux sysfs GPIO support not available in this configuration\n");
}
const char linuxgpio_desc[] = "GPIO bitbanging using the Linux sysfs interface (not available)";
#endif /* HAVE_LINUXGPIO */
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