1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2
3 #include <errno.h>
4 #include <limits.h>
5 #include <stdarg.h>
6 #include <stdio.h>
7 #include <stdlib.h>
8 #include <sys/io.h>
9
10 #define POST_DEFAULT_IO_PORT 0x80
11
usage(char * progname,const char * error,...)12 void usage(char *progname, const char *error, ...)
13 {
14 printf("Usage: %s <VALUE> [PORT]\n", progname);
15 printf("The VALUE argument is an integer between 0x00 and 0xff\n");
16 printf("The PORT argument is an integer between 0x00 and 0xffff\n");
17
18 if (error) {
19 va_list args;
20
21 va_start(args, error);
22 vprintf(error, args);
23 va_end(args);
24 };
25 }
26
check_int(long val,int min,int max,int err,char * string,char * endptr,char * progname)27 void check_int(long val, int min, int max, int err, char *string, char *endptr,
28 char *progname)
29 {
30 if (val < min || val > max) {
31 usage(progname,
32 "\nError: The value has to be between 0x%x and 0x%x\n",
33 min, max);
34 exit(EXIT_FAILURE);
35 }
36
37 if (endptr == string || *endptr != '\0') {
38 usage(progname, "\nError: An integer is required\n");
39 exit(EXIT_FAILURE);
40 }
41
42 if ((err) && (!val)) {
43 perror("strtol");
44 exit(EXIT_FAILURE);
45 }
46 }
47
main(int argc,char * argv[])48 int main(int argc, char *argv[])
49 {
50 unsigned long val;
51 unsigned long port = POST_DEFAULT_IO_PORT;
52 char *endptr;
53 int err;
54
55 if (argc != 2 && argc != 3) {
56 usage(argv[0], NULL);
57 exit(EXIT_FAILURE);
58 }
59
60 val = strtol(argv[1], &endptr, 0);
61 err = errno;
62 check_int(val, 0x00, 0xff, err, argv[1], endptr, argv[0]);
63
64 if (argc > 2) {
65 port = strtol(argv[2], &endptr, 0);
66 err = errno;
67 check_int(port, 0x0000, 0xffff, err, argv[2], endptr, argv[0]);
68 }
69
70 err = iopl(3);
71 if (err == -1) {
72 perror("Not root");
73 exit(EXIT_FAILURE);
74 }
75
76 outb(val, port);
77
78 return 0;
79 }
80