Merge pull request #917 from asmirnou/iss45256-sysfs-gpio
Fix permission denied error in linuxgpio programmer
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commit
fe991b8214
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@ -27,6 +27,7 @@
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#include <fcntl.h>
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#include <unistd.h>
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#include <errno.h>
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#include <sys/stat.h>
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#include "avrdude.h"
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#include "libavrdude.h"
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@ -108,7 +109,8 @@ static int linuxgpio_dir(unsigned int gpio, unsigned int dir)
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fd = open(buf, O_WRONLY);
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if (fd < 0) {
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perror("Can't open gpioX/direction");
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snprintf(buf, sizeof(buf), "Can't open gpio%u/direction", gpio);
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perror(buf);
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return fd;
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}
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@ -138,6 +140,11 @@ static int linuxgpio_dir_in(unsigned int gpio)
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#define N_GPIO (PIN_MAX + 1)
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/* Delay between checks for successful GPIO export (100ms) */
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#define GPIO_SYSFS_OPEN_DELAY 100000
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/* Number of retries to check for successful GPIO exports */
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#define GPIO_SYSFS_OPEN_RETRIES 10
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/*
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* an array which holds open FDs to /sys/class/gpio/gpioXX/value for all needed pins
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*/
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@ -235,6 +242,8 @@ static void linuxgpio_powerdown(const PROGRAMMER *pgm) {
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static int linuxgpio_open(PROGRAMMER *pgm, const char *port) {
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int r, i, pin;
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char gpio_path[60];
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struct stat stat_buf;
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if (bitbang_check_prerequisites(pgm) < 0)
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return -1;
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@ -262,13 +271,49 @@ static int linuxgpio_open(PROGRAMMER *pgm, const char *port) {
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pin, strerror(errno));
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return r;
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}
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/* Wait until GPIO directory appears */
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snprintf(gpio_path, sizeof(gpio_path), "/sys/class/gpio/gpio%u", pin);
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unsigned int retry_count;
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for (retry_count = 0; retry_count < GPIO_SYSFS_OPEN_RETRIES; retry_count++) {
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int ret = stat(gpio_path, &stat_buf);
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if (ret == 0) {
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break;
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} else if (ret < 0 && errno != ENOENT) {
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linuxgpio_unexport(pin);
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return ret;
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}
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usleep(GPIO_SYSFS_OPEN_DELAY);
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}
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/* Write direction, looping in case of EACCES errors due to delayed
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* udev permission rule application after export */
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for (retry_count = 0; retry_count < GPIO_SYSFS_OPEN_RETRIES; retry_count++) {
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usleep(GPIO_SYSFS_OPEN_DELAY);
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if (i == PIN_AVR_MISO)
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r=linuxgpio_dir_in(pin);
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else
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r=linuxgpio_dir_out(pin);
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if (r < 0)
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if (r >= 0)
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break;
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if (errno != EACCES) {
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linuxgpio_unexport(pin);
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return r;
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}
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}
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if (retry_count)
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avrdude_message(MSG_NOTICE2, "%s: needed %d retr%s for linuxgpio_dir_%s(%s)\n",
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progname, retry_count, retry_count > 1? "ies": "y",
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i == PIN_AVR_MISO? "in": "out", avr_pin_name(pin));
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if (r < 0) {
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linuxgpio_unexport(pin);
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return r;
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}
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if ((linuxgpio_fds[pin]=linuxgpio_openfd(pin)) < 0)
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return linuxgpio_fds[pin];
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