src/multimeter.c

   1 /**
   2  * collectd - src/multimeter.c
   3  * Copyright (C) 2005,2006  Peter Holik
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License as published by the
   7  * Free Software Foundation; either version 2 of the License, or (at your
   8  * option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
  18  *
  19  * Authors:
  20  *   Peter Holik <peter at holik.at>
  21  *
  22  * Used multimeter: Metex M-4650CR
  23  **/
  24
  25 #include "collectd.h"
  26 #include "common.h"
  27 #include "plugin.h"
  28
  29 #if HAVE_TERMIOS_H && HAVE_SYS_IOCTL_H && HAVE_MATH_H
  30 # include <termios.h>
  31 # include <sys/ioctl.h>
  32 # include <math.h>
  33 #else
  34 # error "No applicable input method."
  35 #endif
  36
  37 static int fd = -1;
  38
  39 static int multimeter_timeval_sub (struct timeval *tv1, struct timeval *tv2,
  40                 struct timeval *res)
  41 {
  42         if ((tv1->tv_sec < tv2->tv_sec) ||
  43             ((tv1->tv_sec == tv2->tv_sec) && (tv1->tv_usec < tv2->tv_usec)))
  44                 return (-1);
  45
  46         res->tv_sec  = tv1->tv_sec  - tv2->tv_sec;
  47         res->tv_usec = tv1->tv_usec - tv2->tv_usec;
  48
  49         assert ((res->tv_sec > 0) || ((res->tv_sec == 0) && (res->tv_usec > 0)));
  50
  51         while (res->tv_usec < 0)
  52         {
  53                 res->tv_usec += 1000000;
  54                 res->tv_sec--;
  55         }
  56         return (0);
  57 }
  58
  59 #define LINE_LENGTH 14
  60 static int multimeter_read_value(double *value)
  61 {
  62         int retry = 3; /* sometimes we receive garbadge */
  63
  64         do
  65         {
  66                 struct timeval time_end;
  67
  68                 tcflush(fd, TCIFLUSH);
  69
  70                 if (gettimeofday (&time_end, NULL) < 0)
  71                 {
  72                         char errbuf[1024];
  73                         ERROR ("multimeter plugin: gettimeofday failed: %s",
  74                                         sstrerror (errno, errbuf,
  75                                                 sizeof (errbuf)));
  76                         return (-1);
  77                 }
  78                 time_end.tv_sec++;
  79
  80                 while (1)
  81                 {
  82                         char buf[LINE_LENGTH];
  83                         char *range;
  84                         int status;
  85                         fd_set rfds;
  86                         struct timeval timeout;
  87                         struct timeval time_now;
  88
  89                         write(fd, "D", 1);
  90
  91                         FD_ZERO(&rfds);
  92                         FD_SET(fd, &rfds);
  93
  94                         if (gettimeofday (&time_now, NULL) < 0)
  95                         {
  96                                 char errbuf[1024];
  97                                 ERROR ("multimeter plugin: "
  98                                                 "gettimeofday failed: %s",
  99                                                 sstrerror (errno, errbuf,
 100                                                         sizeof (errbuf)));
 101                                 return (-1);
 102                         }
 103                         if (multimeter_timeval_sub (&time_end, &time_now, &timeout) == -1)
 104                                 break;
 105
 106                         status = select(fd+1, &rfds, NULL, NULL, &timeout);
 107
 108                         if (status > 0) /* usually we succeed */
 109                         {
 110                                 status = read(fd, buf, LINE_LENGTH);
 111
 112                                 if ((status < 0) && ((errno == EAGAIN) || (errno == EINTR)))
 113                                         continue;
 114
 115                                 /* Format: "DC 00.000mV  \r" */
 116                                 if (status > 0 && status == LINE_LENGTH)
 117                                 {
 118                                         *value = strtod(buf + 2, &range);
 119
 120                                         if ( range > (buf + 6) )
 121                                         {
 122                                                 range = buf + 9;
 123
 124                                                 switch ( *range )
 125                                                 {
 126                                                         case 'p': *value *= 1.0E-12; break;
 127                                                         case 'n': *value *= 1.0E-9; break;
 128                                                         case 'u': *value *= 1.0E-6; break;
 129                                                         case 'm': *value *= 1.0E-3; break;
 130                                                         case 'k': *value *= 1.0E3; break;
 131                                                         case 'M': *value *= 1.0E6; break;
 132                                                         case 'G': *value *= 1.0E9; break;
 133                                                 }
 134                                         }
 135                                         else
 136                                                 return (-1); /* Overflow */
 137
 138                                         return (0); /* value received */
 139                                 }
 140                                 else break;
 141                         }
 142                         else if (!status) /* Timeout */
 143                         {
 144                                 break;
 145                         }
 146                         else if ((status == -1) && ((errno == EAGAIN) || (errno == EINTR)))
 147                         {
 148                                 continue;
 149                         }
 150                         else /* status == -1 */
 151                         {
 152                                 char errbuf[1024];
 153                                 ERROR ("multimeter plugin: "
 154                                                 "select failed: %s",
 155                                                 sstrerror (errno, errbuf, sizeof (errbuf)));
 156                                 break;
 157                         }
 158                 }
 159         } while (--retry);
 160
 161         return (-2);  /* no value received */
 162 } /* int multimeter_read_value */
 163
 164 static int multimeter_init (void)
 165 {
 166         int i;
 167         char device[] = "/dev/ttyS ";
 168
 169         for (i = 0; i < 10; i++)
 170         {
 171                 device[strlen(device)-1] = i + '0';
 172
 173                 if ((fd = open(device, O_RDWR | O_NOCTTY)) > 0)
 174                 {
 175                         struct termios tios;
 176                         int rts = TIOCM_RTS;
 177                         double value;
 178
 179                         tios.c_cflag = B1200 | CS7 | CSTOPB | CREAD | CLOCAL;
 180                         tios.c_iflag = IGNBRK | IGNPAR;
 181                         tios.c_oflag = 0;
 182                         tios.c_lflag = 0;
 183                         tios.c_cc[VTIME] = 3;
 184                         tios.c_cc[VMIN]  = LINE_LENGTH;
 185
 186                         tcflush(fd, TCIFLUSH);
 187                         tcsetattr(fd, TCSANOW, &tios);
 188                         ioctl(fd, TIOCMBIC, &rts);
 189
 190                         if (multimeter_read_value (&value) < -1)
 191                         {
 192                                 close (fd);
 193                                 fd = -1;
 194                         }
 195                         else
 196                         {
 197                                 INFO ("multimeter plugin: Device "
 198                                                 "found at %s", device);
 199                                 return (0);
 200                         }
 201                 }
 202         }
 203
 204         ERROR ("multimeter plugin: No device found");
 205         return (-1);
 206 }
 207 #undef LINE_LENGTH
 208
 209 static void multimeter_submit (double value)
 210 {
 211         value_t values[1];
 212         value_list_t vl = VALUE_LIST_INIT;
 213
 214         values[0].gauge = value;
 215
 216         vl.values = values;
 217         vl.values_len = 1;
 218         vl.time = time (NULL);
 219         sstrncpy (vl.host, hostname_g, sizeof (vl.host));
 220         sstrncpy (vl.plugin, "multimeter", sizeof (vl.plugin));
 221
 222         plugin_dispatch_values ("multimeter", &vl);
 223 }
 224
 225 static int multimeter_read (void)
 226 {
 227         double value;
 228
 229         if (fd < 0)
 230                 return (-1);
 231
 232         if (multimeter_read_value (&value) != 0)
 233                 return (-1);
 234
 235         multimeter_submit (value);
 236         return (0);
 237 } /* int multimeter_read */
 238
 239 static int multimeter_shutdown (void)
 240 {
 241         if (fd >= 0)
 242         {
 243                 close (fd);
 244                 fd = -1;
 245         }
 246
 247         return (0);
 248 }
 249
 250 void module_register (void)
 251 {
 252         plugin_register_init ("multimeter", multimeter_init);
 253         plugin_register_read ("multimeter", multimeter_read);
 254         plugin_register_shutdown ("multimeter", multimeter_shutdown);
 255 } /* void module_register */