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                         status = swrite (fd, "D", 1);
  90                         if (status < 0)
  91                         {
  92                                 ERROR ("multimeter plugin: swrite failed.");
  93                                 return (-1);
  94                         }
  95
  96                         FD_ZERO(&rfds);
  97                         FD_SET(fd, &rfds);
  98
  99                         if (gettimeofday (&time_now, NULL) < 0)
 100                         {
 101                                 char errbuf[1024];
 102                                 ERROR ("multimeter plugin: "
 103                                                 "gettimeofday failed: %s",
 104                                                 sstrerror (errno, errbuf,
 105                                                         sizeof (errbuf)));
 106                                 return (-1);
 107                         }
 108                         if (multimeter_timeval_sub (&time_end, &time_now, &timeout) == -1)
 109                                 break;
 110
 111                         status = select(fd+1, &rfds, NULL, NULL, &timeout);
 112
 113                         if (status > 0) /* usually we succeed */
 114                         {
 115                                 status = read(fd, buf, LINE_LENGTH);
 116
 117                                 if ((status < 0) && ((errno == EAGAIN) || (errno == EINTR)))
 118                                         continue;
 119
 120                                 /* Format: "DC 00.000mV  \r" */
 121                                 if (status > 0 && status == LINE_LENGTH)
 122                                 {
 123                                         *value = strtod(buf + 2, &range);
 124
 125                                         if ( range > (buf + 6) )
 126                                         {
 127                                                 range = buf + 9;
 128
 129                                                 switch ( *range )
 130                                                 {
 131                                                         case 'p': *value *= 1.0E-12; break;
 132                                                         case 'n': *value *= 1.0E-9; break;
 133                                                         case 'u': *value *= 1.0E-6; break;
 134                                                         case 'm': *value *= 1.0E-3; break;
 135                                                         case 'k': *value *= 1.0E3; break;
 136                                                         case 'M': *value *= 1.0E6; break;
 137                                                         case 'G': *value *= 1.0E9; break;
 138                                                 }
 139                                         }
 140                                         else
 141                                                 return (-1); /* Overflow */
 142
 143                                         return (0); /* value received */
 144                                 }
 145                                 else break;
 146                         }
 147                         else if (!status) /* Timeout */
 148                         {
 149                                 break;
 150                         }
 151                         else if ((status == -1) && ((errno == EAGAIN) || (errno == EINTR)))
 152                         {
 153                                 continue;
 154                         }
 155                         else /* status == -1 */
 156                         {
 157                                 char errbuf[1024];
 158                                 ERROR ("multimeter plugin: "
 159                                                 "select failed: %s",
 160                                                 sstrerror (errno, errbuf, sizeof (errbuf)));
 161                                 break;
 162                         }
 163                 }
 164         } while (--retry);
 165
 166         return (-2);  /* no value received */
 167 } /* int multimeter_read_value */
 168
 169 static int multimeter_init (void)
 170 {
 171         int i;
 172         char device[] = "/dev/ttyS ";
 173
 174         for (i = 0; i < 10; i++)
 175         {
 176                 device[strlen(device)-1] = i + '0';
 177
 178                 if ((fd = open(device, O_RDWR | O_NOCTTY)) > 0)
 179                 {
 180                         struct termios tios;
 181                         int rts = TIOCM_RTS;
 182                         double value;
 183
 184                         tios.c_cflag = B1200 | CS7 | CSTOPB | CREAD | CLOCAL;
 185                         tios.c_iflag = IGNBRK | IGNPAR;
 186                         tios.c_oflag = 0;
 187                         tios.c_lflag = 0;
 188                         tios.c_cc[VTIME] = 3;
 189                         tios.c_cc[VMIN]  = LINE_LENGTH;
 190
 191                         tcflush(fd, TCIFLUSH);
 192                         tcsetattr(fd, TCSANOW, &tios);
 193                         ioctl(fd, TIOCMBIC, &rts);
 194
 195                         if (multimeter_read_value (&value) < -1)
 196                         {
 197                                 close (fd);
 198                                 fd = -1;
 199                         }
 200                         else
 201                         {
 202                                 INFO ("multimeter plugin: Device "
 203                                                 "found at %s", device);
 204                                 return (0);
 205                         }
 206                 }
 207         }
 208
 209         ERROR ("multimeter plugin: No device found");
 210         return (-1);
 211 }
 212 #undef LINE_LENGTH
 213
 214 static void multimeter_submit (double value)
 215 {
 216         value_t values[1];
 217         value_list_t vl = VALUE_LIST_INIT;
 218
 219         values[0].gauge = value;
 220
 221         vl.values = values;
 222         vl.values_len = 1;
 223         vl.time = time (NULL);
 224         sstrncpy (vl.host, hostname_g, sizeof (vl.host));
 225         sstrncpy (vl.plugin, "multimeter", sizeof (vl.plugin));
 226         sstrncpy (vl.type, "multimeter", sizeof (vl.type));
 227
 228         plugin_dispatch_values (&vl);
 229 }
 230
 231 static int multimeter_read (void)
 232 {
 233         double value;
 234
 235         if (fd < 0)
 236                 return (-1);
 237
 238         if (multimeter_read_value (&value) != 0)
 239                 return (-1);
 240
 241         multimeter_submit (value);
 242         return (0);
 243 } /* int multimeter_read */
 244
 245 static int multimeter_shutdown (void)
 246 {
 247         if (fd >= 0)
 248         {
 249                 close (fd);
 250                 fd = -1;
 251         }
 252
 253         return (0);
 254 }
 255
 256 void module_register (void)
 257 {
 258         plugin_register_init ("multimeter", multimeter_init);
 259         plugin_register_read ("multimeter", multimeter_read);
 260         plugin_register_shutdown ("multimeter", multimeter_shutdown);
 261 } /* void module_register */