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
 25int 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
 99exit_close_error:
100	gpiotools_release_linehandle(fd);
101exit_error:
102	return ret;
103}
104
105void 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
119int 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			/*
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
142			 */
143			if (i < GPIOHANDLES_MAX)
144				lines[i] = strtoul(optarg, NULL, 10);
145
146			i++;
147			break;
148		case '?':
149			print_usage();
150			return -1;
151		}
152	}
153
154	if (i >= GPIOHANDLES_MAX) {
155		fprintf(stderr,
156			"Only %d occurrences of '-o' are allowed, %d were found\n",
157			GPIOHANDLES_MAX, i + 1);
158		return -1;
159	}
160
161	nlines = i;
162
163	if (!device_name || !nlines) {
164		print_usage();
165		return -1;
166	}
167	return hammer_device(device_name, lines, nlines, loops);
168}