1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * gpio-hammer - example swiss army knife to shake GPIO lines on a system
4 *
5 * Copyright (C) 2016 Linus Walleij
6 *
7 * Usage:
8 * gpio-hammer -n <device-name> -o <offset1> -o <offset2>
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 #include "gpio-utils.h"
24
hammer_device(const char * device_name,unsigned int * lines,int nlines,unsigned int loops)25 int hammer_device(const char *device_name, unsigned int *lines, int nlines,
26 unsigned int loops)
27 {
28 struct gpiohandle_data data;
29 char swirr[] = "-\\|/";
30 int fd;
31 int ret;
32 int i, j;
33 unsigned int iteration = 0;
34
35 memset(&data.values, 0, sizeof(data.values));
36 ret = gpiotools_request_linehandle(device_name, lines, nlines,
37 GPIOHANDLE_REQUEST_OUTPUT, &data,
38 "gpio-hammer");
39 if (ret < 0)
40 goto exit_error;
41 else
42 fd = ret;
43
44 ret = gpiotools_get_values(fd, &data);
45 if (ret < 0)
46 goto exit_close_error;
47
48 fprintf(stdout, "Hammer lines [");
49 for (i = 0; i < nlines; i++) {
50 fprintf(stdout, "%d", lines[i]);
51 if (i != (nlines - 1))
52 fprintf(stdout, ", ");
53 }
54 fprintf(stdout, "] on %s, initial states: [", device_name);
55 for (i = 0; i < nlines; i++) {
56 fprintf(stdout, "%d", data.values[i]);
57 if (i != (nlines - 1))
58 fprintf(stdout, ", ");
59 }
60 fprintf(stdout, "]\n");
61
62 /* Hammertime! */
63 j = 0;
64 while (1) {
65 /* Invert all lines so we blink */
66 for (i = 0; i < nlines; i++)
67 data.values[i] = !data.values[i];
68
69 ret = gpiotools_set_values(fd, &data);
70 if (ret < 0)
71 goto exit_close_error;
72
73 /* Re-read values to get status */
74 ret = gpiotools_get_values(fd, &data);
75 if (ret < 0)
76 goto exit_close_error;
77
78 fprintf(stdout, "[%c] ", swirr[j]);
79 j++;
80 if (j == sizeof(swirr)-1)
81 j = 0;
82
83 fprintf(stdout, "[");
84 for (i = 0; i < nlines; i++) {
85 fprintf(stdout, "%d: %d", lines[i], data.values[i]);
86 if (i != (nlines - 1))
87 fprintf(stdout, ", ");
88 }
89 fprintf(stdout, "]\r");
90 fflush(stdout);
91 sleep(1);
92 iteration++;
93 if (loops && iteration == loops)
94 break;
95 }
96 fprintf(stdout, "\n");
97 ret = 0;
98
99 exit_close_error:
100 gpiotools_release_linehandle(fd);
101 exit_error:
102 return ret;
103 }
104
print_usage(void)105 void print_usage(void)
106 {
107 fprintf(stderr, "Usage: gpio-hammer [options]...\n"
108 "Hammer GPIO lines, 0->1->0->1...\n"
109 " -n <name> Hammer GPIOs on a named device (must be stated)\n"
110 " -o <n> Offset[s] to hammer, at least one, several can be stated\n"
111 " [-c <n>] Do <n> loops (optional, infinite loop if not stated)\n"
112 " -? This helptext\n"
113 "\n"
114 "Example:\n"
115 "gpio-hammer -n gpiochip0 -o 4\n"
116 );
117 }
118
main(int argc,char ** argv)119 int main(int argc, char **argv)
120 {
121 const char *device_name = NULL;
122 unsigned int lines[GPIOHANDLES_MAX];
123 unsigned int loops = 0;
124 int nlines;
125 int c;
126 int i;
127
128 i = 0;
129 while ((c = getopt(argc, argv, "c:n:o:?")) != -1) {
130 switch (c) {
131 case 'c':
132 loops = strtoul(optarg, NULL, 10);
133 break;
134 case 'n':
135 device_name = optarg;
136 break;
137 case 'o':
138 lines[i] = strtoul(optarg, NULL, 10);
139 i++;
140 break;
141 case '?':
142 print_usage();
143 return -1;
144 }
145 }
146 nlines = i;
147
148 if (!device_name || !nlines) {
149 print_usage();
150 return -1;
151 }
152 return hammer_device(device_name, lines, nlines, loops);
153 }
154