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
26 struct gpio_flag {
27 char *name;
28 unsigned long long mask;
29 };
30
31 struct gpio_flag flagnames[] = {
32 {
33 .name = "used",
34 .mask = GPIO_V2_LINE_FLAG_USED,
35 },
36 {
37 .name = "input",
38 .mask = GPIO_V2_LINE_FLAG_INPUT,
39 },
40 {
41 .name = "output",
42 .mask = GPIO_V2_LINE_FLAG_OUTPUT,
43 },
44 {
45 .name = "active-low",
46 .mask = GPIO_V2_LINE_FLAG_ACTIVE_LOW,
47 },
48 {
49 .name = "open-drain",
50 .mask = GPIO_V2_LINE_FLAG_OPEN_DRAIN,
51 },
52 {
53 .name = "open-source",
54 .mask = GPIO_V2_LINE_FLAG_OPEN_SOURCE,
55 },
56 {
57 .name = "pull-up",
58 .mask = GPIO_V2_LINE_FLAG_BIAS_PULL_UP,
59 },
60 {
61 .name = "pull-down",
62 .mask = GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN,
63 },
64 {
65 .name = "bias-disabled",
66 .mask = GPIO_V2_LINE_FLAG_BIAS_DISABLED,
67 },
68 };
69
print_attributes(struct gpio_v2_line_info * info)70 static void print_attributes(struct gpio_v2_line_info *info)
71 {
72 int i;
73 const char *field_format = "%s";
74
75 for (i = 0; i < ARRAY_SIZE(flagnames); i++) {
76 if (info->flags & flagnames[i].mask) {
77 fprintf(stdout, field_format, flagnames[i].name);
78 field_format = ", %s";
79 }
80 }
81
82 if ((info->flags & GPIO_V2_LINE_FLAG_EDGE_RISING) &&
83 (info->flags & GPIO_V2_LINE_FLAG_EDGE_FALLING))
84 fprintf(stdout, field_format, "both-edges");
85 else if (info->flags & GPIO_V2_LINE_FLAG_EDGE_RISING)
86 fprintf(stdout, field_format, "rising-edge");
87 else if (info->flags & GPIO_V2_LINE_FLAG_EDGE_FALLING)
88 fprintf(stdout, field_format, "falling-edge");
89
90 for (i = 0; i < info->num_attrs; i++) {
91 if (info->attrs[i].id == GPIO_V2_LINE_ATTR_ID_DEBOUNCE)
92 fprintf(stdout, ", debounce_period=%dusec",
93 info->attrs[i].debounce_period_us);
94 }
95 }
96
list_device(const char * device_name)97 int list_device(const char *device_name)
98 {
99 struct gpiochip_info cinfo;
100 char *chrdev_name;
101 int fd;
102 int ret;
103 int i;
104
105 ret = asprintf(&chrdev_name, "/dev/%s", device_name);
106 if (ret < 0)
107 return -ENOMEM;
108
109 fd = open(chrdev_name, 0);
110 if (fd == -1) {
111 ret = -errno;
112 fprintf(stderr, "Failed to open %s\n", chrdev_name);
113 goto exit_free_name;
114 }
115
116 /* Inspect this GPIO chip */
117 ret = ioctl(fd, GPIO_GET_CHIPINFO_IOCTL, &cinfo);
118 if (ret == -1) {
119 ret = -errno;
120 perror("Failed to issue CHIPINFO IOCTL\n");
121 goto exit_close_error;
122 }
123 fprintf(stdout, "GPIO chip: %s, \"%s\", %u GPIO lines\n",
124 cinfo.name, cinfo.label, cinfo.lines);
125
126 /* Loop over the lines and print info */
127 for (i = 0; i < cinfo.lines; i++) {
128 struct gpio_v2_line_info linfo;
129
130 memset(&linfo, 0, sizeof(linfo));
131 linfo.offset = i;
132
133 ret = ioctl(fd, GPIO_V2_GET_LINEINFO_IOCTL, &linfo);
134 if (ret == -1) {
135 ret = -errno;
136 perror("Failed to issue LINEINFO IOCTL\n");
137 goto exit_close_error;
138 }
139 fprintf(stdout, "\tline %2d:", linfo.offset);
140 if (linfo.name[0])
141 fprintf(stdout, " \"%s\"", linfo.name);
142 else
143 fprintf(stdout, " unnamed");
144 if (linfo.consumer[0])
145 fprintf(stdout, " \"%s\"", linfo.consumer);
146 else
147 fprintf(stdout, " unused");
148 if (linfo.flags) {
149 fprintf(stdout, " [");
150 print_attributes(&linfo);
151 fprintf(stdout, "]");
152 }
153 fprintf(stdout, "\n");
154
155 }
156
157 exit_close_error:
158 if (close(fd) == -1)
159 perror("Failed to close GPIO character device file");
160 exit_free_name:
161 free(chrdev_name);
162 return ret;
163 }
164
print_usage(void)165 void print_usage(void)
166 {
167 fprintf(stderr, "Usage: lsgpio [options]...\n"
168 "List GPIO chips, lines and states\n"
169 " -n <name> List GPIOs on a named device\n"
170 " -? This helptext\n"
171 );
172 }
173
main(int argc,char ** argv)174 int main(int argc, char **argv)
175 {
176 const char *device_name = NULL;
177 int ret;
178 int c;
179
180 while ((c = getopt(argc, argv, "n:")) != -1) {
181 switch (c) {
182 case 'n':
183 device_name = optarg;
184 break;
185 case '?':
186 print_usage();
187 return -1;
188 }
189 }
190
191 if (device_name)
192 ret = list_device(device_name);
193 else {
194 const struct dirent *ent;
195 DIR *dp;
196
197 /* List all GPIO devices one at a time */
198 dp = opendir("/dev");
199 if (!dp) {
200 ret = -errno;
201 goto error_out;
202 }
203
204 ret = -ENOENT;
205 while (ent = readdir(dp), ent) {
206 if (check_prefix(ent->d_name, "gpiochip")) {
207 ret = list_device(ent->d_name);
208 if (ret)
209 break;
210 }
211 }
212
213 ret = 0;
214 if (closedir(dp) == -1) {
215 perror("scanning devices: Failed to close directory");
216 ret = -errno;
217 }
218 }
219 error_out:
220 return ret;
221 }
222