util/post/post.c

   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
  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
  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
  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 }