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 num_lines,unsigned int loops)25 int hammer_device(const char *device_name, unsigned int *lines, int num_lines,
26 unsigned int loops)
27 {
28 struct gpio_v2_line_values values;
29 struct gpio_v2_line_config config;
30 char swirr[] = "-\\|/";
31 int fd;
32 int ret;
33 int i, j;
34 unsigned int iteration = 0;
35
36 memset(&config, 0, sizeof(config));
37 config.flags = GPIO_V2_LINE_FLAG_OUTPUT;
38
39 ret = gpiotools_request_line(device_name, lines, num_lines,
40 &config, "gpio-hammer");
41 if (ret < 0)
42 goto exit_error;
43 else
44 fd = ret;
45
46 values.mask = 0;
47 values.bits = 0;
48 for (i = 0; i < num_lines; i++)
49 gpiotools_set_bit(&values.mask, i);
50
51 ret = gpiotools_get_values(fd, &values);
52 if (ret < 0)
53 goto exit_close_error;
54
55 fprintf(stdout, "Hammer lines [");
56 for (i = 0; i < num_lines; i++) {
57 fprintf(stdout, "%d", lines[i]);
58 if (i != (num_lines - 1))
59 fprintf(stdout, ", ");
60 }
61 fprintf(stdout, "] on %s, initial states: [", device_name);
62 for (i = 0; i < num_lines; i++) {
63 fprintf(stdout, "%d", gpiotools_test_bit(values.bits, i));
64 if (i != (num_lines - 1))
65 fprintf(stdout, ", ");
66 }
67 fprintf(stdout, "]\n");
68
69 /* Hammertime! */
70 j = 0;
71 while (1) {
72 /* Invert all lines so we blink */
73 for (i = 0; i < num_lines; i++)
74 gpiotools_change_bit(&values.bits, i);
75
76 ret = gpiotools_set_values(fd, &values);
77 if (ret < 0)
78 goto exit_close_error;
79
80 /* Re-read values to get status */
81 ret = gpiotools_get_values(fd, &values);
82 if (ret < 0)
83 goto exit_close_error;
84
85 fprintf(stdout, "[%c] ", swirr[j]);
86 j++;
87 if (j == sizeof(swirr) - 1)
88 j = 0;
89
90 fprintf(stdout, "[");
91 for (i = 0; i < num_lines; i++) {
92 fprintf(stdout, "%d: %d", lines[i],
93 gpiotools_test_bit(values.bits, i));
94 if (i != (num_lines - 1))
95 fprintf(stdout, ", ");
96 }
97 fprintf(stdout, "]\r");
98 fflush(stdout);
99 sleep(1);
100 iteration++;
101 if (loops && iteration == loops)
102 break;
103 }
104 fprintf(stdout, "\n");
105 ret = 0;
106
107 exit_close_error:
108 gpiotools_release_line(fd);
109 exit_error:
110 return ret;
111 }
112
print_usage(void)113 void print_usage(void)
114 {
115 fprintf(stderr, "Usage: gpio-hammer [options]...\n"
116 "Hammer GPIO lines, 0->1->0->1...\n"
117 " -n <name> Hammer GPIOs on a named device (must be stated)\n"
118 " -o <n> Offset[s] to hammer, at least one, several can be stated\n"
119 " [-c <n>] Do <n> loops (optional, infinite loop if not stated)\n"
120 " -? This helptext\n"
121 "\n"
122 "Example:\n"
123 "gpio-hammer -n gpiochip0 -o 4\n"
124 );
125 }
126
main(int argc,char ** argv)127 int main(int argc, char **argv)
128 {
129 const char *device_name = NULL;
130 unsigned int lines[GPIOHANDLES_MAX];
131 unsigned int loops = 0;
132 int num_lines;
133 int c;
134 int i;
135
136 i = 0;
137 while ((c = getopt(argc, argv, "c:n:o:?")) != -1) {
138 switch (c) {
139 case 'c':
140 loops = strtoul(optarg, NULL, 10);
141 break;
142 case 'n':
143 device_name = optarg;
144 break;
145 case 'o':
146 /*
147 * Avoid overflow. Do not immediately error, we want to
148 * be able to accurately report on the amount of times
149 * '-o' was given to give an accurate error message
150 */
151 if (i < GPIOHANDLES_MAX)
152 lines[i] = strtoul(optarg, NULL, 10);
153
154 i++;
155 break;
156 case '?':
157 print_usage();
158 return -1;
159 }
160 }
161
162 if (i >= GPIOHANDLES_MAX) {
163 fprintf(stderr,
164 "Only %d occurrences of '-o' are allowed, %d were found\n",
165 GPIOHANDLES_MAX, i + 1);
166 return -1;
167 }
168
169 num_lines = i;
170
171 if (!device_name || !num_lines) {
172 print_usage();
173 return -1;
174 }
175 return hammer_device(device_name, lines, num_lines, loops);
176 }
177