src/host/layer23/src/mobile/gps.c

   1 /*
   2  * (C) 2010 by Andreas Eversberg <jolly@eversberg.eu>
   3  *
   4  * All Rights Reserved
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License along
  17  * with this program; if not, write to the Free Software Foundation, Inc.,
  18  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  19  *
  20  */
  21
  22 #include <stdio.h>
  23 #include <sys/file.h>
  24 #include <termios.h>
  25 #include <unistd.h>
  26 #include <stdlib.h>
  27 #include <errno.h>
  28
  29 #include <osmocore/utils.h>
  30
  31 #include <osmocom/bb/common/osmocom_data.h>
  32 #include <osmocom/bb/mobile/gps.h>
  33
  34 struct gps gps = {
  35         0,
  36         "/dev/ttyACM0",
  37         0
  38 };
  39
  40 static struct bsc_fd gps_bfd;
  41 static struct termios gps_termios, gps_old_termios;
  42
  43 static int gps_line(char *line)
  44 {
  45         if (!!strncmp(line, "$GPGLL", 6))
  46                 return 0;
  47         line += 7;
  48         if (strlen(line) < 37)
  49                 return 0;
  50         line[37] = '\0';
  51         /* ddmm.mmmm,N,dddmm.mmmm,E,hhmmss.mmm,A */
  52
  53         printf("'%s'\n", line);
  54
  55         return 0;
  56 }
  57
  58 static int nmea_checksum(char *line)
  59 {
  60         uint8_t checksum = 0;
  61
  62         while (*line) {
  63                 if (*line == '$') {
  64                         line++;
  65                         continue;
  66                 }
  67                 if (*line == '*')
  68                         break;
  69                 checksum ^= *line++;
  70         }
  71         return (strtoul(line+1, NULL, 16) == checksum);
  72 }
  73
  74 int gps_cb(struct bsc_fd *bfd, unsigned int what)
  75 {
  76         char buff[128];
  77         static char line[128];
  78         static int lpos = 0;
  79         int i = 0, len;
  80
  81         len = read(bfd->fd, buff, sizeof(buff));
  82         if (len <= 0) {
  83                 fprintf(stderr, "error reading GPS device (errno=%d)\n", errno);
  84                 return len;
  85         }
  86         while(i < len) {
  87                 if (buff[i] == 13) {
  88                         i++;
  89                         continue;
  90                 }
  91                 if (buff[i] == 10) {
  92                         line[lpos] = '\0';
  93                         lpos = 0;
  94                         i++;
  95                         if (!nmea_checksum(line))
  96                                 fprintf(stderr, "NMEA checksum error\n");
  97                         else
  98                                 gps_line(line);
  99                         continue;
 100                 }
 101                 line[lpos++] = buff[i++];
 102                 if (lpos == sizeof(line))
 103                         lpos--;
 104         }
 105
 106         return 0;
 107 }
 108
 109 int gps_open(void)
 110 {
 111         int baud = 0;
 112
 113         if (gps_bfd.fd > 0)
 114                 return 0;
 115         gps_bfd.data = NULL;
 116         gps_bfd.when = BSC_FD_READ;
 117         gps_bfd.cb = gps_cb;
 118         gps_bfd.fd = open(gps.device, O_RDONLY);
 119         if (gps_bfd.fd < 0)
 120                 return gps_bfd.fd;
 121
 122         switch (gps.baud) {
 123         case   4800:
 124                 baud = B4800;      break;
 125         case   9600:
 126                 baud = B9600;      break;
 127         case  19200:
 128                 baud = B19200;     break;
 129         case  38400:
 130                 baud = B38400;     break;
 131         case  57600:
 132                 baud = B57600;     break;
 133         case 115200:
 134                 baud = B115200;    break;
 135         }
 136
 137         if (isatty(gps_bfd.fd))
 138         {
 139                 /* get termios */
 140                 tcgetattr(gps_bfd.fd, &gps_old_termios);
 141                 tcgetattr(gps_bfd.fd, &gps_termios);
 142                 /* set baud */
 143                 if (baud) {
 144                         gps_termios.c_cflag |= baud;
 145                         cfsetispeed(&gps_termios, baud);
 146                         cfsetospeed(&gps_termios, baud);
 147                 }
 148                 if (tcsetattr(gps_bfd.fd, TCSANOW, &gps_termios))
 149                         printf("Failed to set termios for GPS\n");
 150         }
 151
 152         bsc_register_fd(&gps_bfd);
 153
 154         return 0;
 155 }
 156
 157 void gps_close(void)
 158 {
 159         if (gps_bfd.fd <= 0)
 160                 return;
 161
 162         bsc_unregister_fd(&gps_bfd);
 163
 164         if (isatty(gps_bfd.fd))
 165                 tcsetattr(gps_bfd.fd, TCSANOW, &gps_old_termios);
 166
 167         close(gps_bfd.fd);
 168         gps_bfd.fd = -1; /* -1 or 0 indicates: 'close' */
 169 }
 170
 171