1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * GPIO character device helper for reading chip information. 4 * 5 * Copyright (C) 2021 Bartosz Golaszewski <brgl@bgdev.pl> 6 */ 7 8 #include <fcntl.h> 9 #include <linux/gpio.h> 10 #include <stdio.h> 11 #include <stdlib.h> 12 #include <string.h> 13 #include <sys/ioctl.h> 14 #include <sys/types.h> 15 16 static void print_usage(void) 17 { 18 printf("usage:\n"); 19 printf(" gpio-chip-info <chip path> [name|label|num-lines]\n"); 20 } 21 22 int main(int argc, char **argv) 23 { 24 struct gpiochip_info info; 25 int fd, ret; 26 27 if (argc != 3) { 28 print_usage(); 29 return EXIT_FAILURE; 30 } 31 32 fd = open(argv[1], O_RDWR); 33 if (fd < 0) { 34 perror("unable to open the GPIO chip"); 35 return EXIT_FAILURE; 36 } 37 38 memset(&info, 0, sizeof(info)); 39 ret = ioctl(fd, GPIO_GET_CHIPINFO_IOCTL, &info); 40 if (ret) { 41 perror("chip info ioctl failed"); 42 return EXIT_FAILURE; 43 } 44 45 if (strcmp(argv[2], "name") == 0) { 46 printf("%s\n", info.name); 47 } else if (strcmp(argv[2], "label") == 0) { 48 printf("%s\n", info.label); 49 } else if (strcmp(argv[2], "num-lines") == 0) { 50 printf("%u\n", info.lines); 51 } else { 52 fprintf(stderr, "unknown command: %s\n", argv[2]); 53 return EXIT_FAILURE; 54 } 55 56 return EXIT_SUCCESS; 57 } 58