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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * lsgpio - example on how to list the GPIO lines on a system
4 *
5 * Copyright (C) 2015 Linus Walleij
6 *
7 * Usage:
8 * lsgpio <-n device-name>
9 */
10
11#include <unistd.h>
12#include <stdlib.h>
13#include <stdbool.h>
14#include <stdio.h>
15#include <dirent.h>
16#include <errno.h>
17#include <string.h>
18#include <poll.h>
19#include <fcntl.h>
20#include <getopt.h>
21#include <sys/ioctl.h>
22#include <linux/gpio.h>
23
24#include "gpio-utils.h"
25
26struct gpio_flag {
27 char *name;
28 unsigned long mask;
29};
30
31struct gpio_flag flagnames[] = {
32 {
33 .name = "kernel",
34 .mask = GPIOLINE_FLAG_KERNEL,
35 },
36 {
37 .name = "output",
38 .mask = GPIOLINE_FLAG_IS_OUT,
39 },
40 {
41 .name = "active-low",
42 .mask = GPIOLINE_FLAG_ACTIVE_LOW,
43 },
44 {
45 .name = "open-drain",
46 .mask = GPIOLINE_FLAG_OPEN_DRAIN,
47 },
48 {
49 .name = "open-source",
50 .mask = GPIOLINE_FLAG_OPEN_SOURCE,
51 },
52 {
53 .name = "pull-up",
54 .mask = GPIOLINE_FLAG_BIAS_PULL_UP,
55 },
56 {
57 .name = "pull-down",
58 .mask = GPIOLINE_FLAG_BIAS_PULL_DOWN,
59 },
60 {
61 .name = "bias-disabled",
62 .mask = GPIOLINE_FLAG_BIAS_DISABLE,
63 },
64};
65
66void print_flags(unsigned long flags)
67{
68 int i;
69 int printed = 0;
70
71 for (i = 0; i < ARRAY_SIZE(flagnames); i++) {
72 if (flags & flagnames[i].mask) {
73 if (printed)
74 fprintf(stdout, " ");
75 fprintf(stdout, "%s", flagnames[i].name);
76 printed++;
77 }
78 }
79}
80
81int list_device(const char *device_name)
82{
83 struct gpiochip_info cinfo;
84 char *chrdev_name;
85 int fd;
86 int ret;
87 int i;
88
89 ret = asprintf(&chrdev_name, "/dev/%s", device_name);
90 if (ret < 0)
91 return -ENOMEM;
92
93 fd = open(chrdev_name, 0);
94 if (fd == -1) {
95 ret = -errno;
96 fprintf(stderr, "Failed to open %s\n", chrdev_name);
97 goto exit_free_name;
98 }
99
100 /* Inspect this GPIO chip */
101 ret = ioctl(fd, GPIO_GET_CHIPINFO_IOCTL, &cinfo);
102 if (ret == -1) {
103 ret = -errno;
104 perror("Failed to issue CHIPINFO IOCTL\n");
105 goto exit_close_error;
106 }
107 fprintf(stdout, "GPIO chip: %s, \"%s\", %u GPIO lines\n",
108 cinfo.name, cinfo.label, cinfo.lines);
109
110 /* Loop over the lines and print info */
111 for (i = 0; i < cinfo.lines; i++) {
112 struct gpioline_info linfo;
113
114 memset(&linfo, 0, sizeof(linfo));
115 linfo.line_offset = i;
116
117 ret = ioctl(fd, GPIO_GET_LINEINFO_IOCTL, &linfo);
118 if (ret == -1) {
119 ret = -errno;
120 perror("Failed to issue LINEINFO IOCTL\n");
121 goto exit_close_error;
122 }
123 fprintf(stdout, "\tline %2d:", linfo.line_offset);
124 if (linfo.name[0])
125 fprintf(stdout, " \"%s\"", linfo.name);
126 else
127 fprintf(stdout, " unnamed");
128 if (linfo.consumer[0])
129 fprintf(stdout, " \"%s\"", linfo.consumer);
130 else
131 fprintf(stdout, " unused");
132 if (linfo.flags) {
133 fprintf(stdout, " [");
134 print_flags(linfo.flags);
135 fprintf(stdout, "]");
136 }
137 fprintf(stdout, "\n");
138
139 }
140
141exit_close_error:
142 if (close(fd) == -1)
143 perror("Failed to close GPIO character device file");
144exit_free_name:
145 free(chrdev_name);
146 return ret;
147}
148
149void print_usage(void)
150{
151 fprintf(stderr, "Usage: lsgpio [options]...\n"
152 "List GPIO chips, lines and states\n"
153 " -n <name> List GPIOs on a named device\n"
154 " -? This helptext\n"
155 );
156}
157
158int main(int argc, char **argv)
159{
160 const char *device_name = NULL;
161 int ret;
162 int c;
163
164 while ((c = getopt(argc, argv, "n:")) != -1) {
165 switch (c) {
166 case 'n':
167 device_name = optarg;
168 break;
169 case '?':
170 print_usage();
171 return -1;
172 }
173 }
174
175 if (device_name)
176 ret = list_device(device_name);
177 else {
178 const struct dirent *ent;
179 DIR *dp;
180
181 /* List all GPIO devices one at a time */
182 dp = opendir("/dev");
183 if (!dp) {
184 ret = -errno;
185 goto error_out;
186 }
187
188 ret = -ENOENT;
189 while (ent = readdir(dp), ent) {
190 if (check_prefix(ent->d_name, "gpiochip")) {
191 ret = list_device(ent->d_name);
192 if (ret)
193 break;
194 }
195 }
196
197 ret = 0;
198 if (closedir(dp) == -1) {
199 perror("scanning devices: Failed to close directory");
200 ret = -errno;
201 }
202 }
203error_out:
204 return ret;
205}