1 // SPDX-License-Identifier: GPL-2.0-only
3 * gpio-hammer - example swiss army knife to shake GPIO lines on a system
5 * Copyright (C) 2016 Linus Walleij
8 * gpio-hammer -n <device-name> -o <offset1> -o <offset2>
21 #include <sys/ioctl.h>
22 #include <linux/gpio.h>
23 #include "gpio-utils.h"
25 int hammer_device(const char *device_name, unsigned int *lines, int nlines,
28 struct gpiohandle_data data;
29 char swirr[] = "-\\|/";
33 unsigned int iteration = 0;
35 memset(&data.values, 0, sizeof(data.values));
36 ret = gpiotools_request_linehandle(device_name, lines, nlines,
37 GPIOHANDLE_REQUEST_OUTPUT, &data,
44 ret = gpiotools_get_values(fd, &data);
46 goto exit_close_error;
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, ", ");
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, ", ");
60 fprintf(stdout, "]\n");
65 /* Invert all lines so we blink */
66 for (i = 0; i < nlines; i++)
67 data.values[i] = !data.values[i];
69 ret = gpiotools_set_values(fd, &data);
71 goto exit_close_error;
73 /* Re-read values to get status */
74 ret = gpiotools_get_values(fd, &data);
76 goto exit_close_error;
78 fprintf(stdout, "[%c] ", swirr[j]);
80 if (j == sizeof(swirr) - 1)
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, ", ");
89 fprintf(stdout, "]\r");
93 if (loops && iteration == loops)
96 fprintf(stdout, "\n");
100 gpiotools_release_linehandle(fd);
105 void print_usage(void)
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"
115 "gpio-hammer -n gpiochip0 -o 4\n"
119 int main(int argc, char **argv)
121 const char *device_name = NULL;
122 unsigned int lines[GPIOHANDLES_MAX];
123 unsigned int loops = 0;
129 while ((c = getopt(argc, argv, "c:n:o:?")) != -1) {
132 loops = strtoul(optarg, NULL, 10);
135 device_name = optarg;
139 * Avoid overflow. Do not immediately error, we want to
140 * be able to accurately report on the amount of times
141 * '-o' was given to give an accurate error message
143 if (i < GPIOHANDLES_MAX)
144 lines[i] = strtoul(optarg, NULL, 10);
154 if (i >= GPIOHANDLES_MAX) {
156 "Only %d occurrences of '-o' are allowed, %d were found\n",
157 GPIOHANDLES_MAX, i + 1);
163 if (!device_name || !nlines) {
167 return hammer_device(device_name, lines, nlines, loops);