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
  26 #include "collectd.h"
  27 #include "common.h"
  28 #include "plugin.h"
  29
  30 #include <termios.h>
  31 #include <sys/ioctl.h>
  32 #include <math.h>
  33
  34 #define MODULE_NAME "multimeter"
  35
  36 static char *multimeter_file = "multimeter.rrd";
  37
  38 static char *ds_def[] =
  39 {
  40         "DS:value:GAUGE:"COLLECTD_HEARTBEAT":U:U",
  41         NULL
  42 };
  43 static int ds_num = 1;
  44
  45 static int fd = -1;
  46
  47 static int multimeter_timeval_sub (struct timeval *tv1, struct timeval *tv2,
  48                 struct timeval *res)
  49 {
  50         if ((tv1->tv_sec < tv2->tv_sec) ||
  51             ((tv1->tv_sec == tv2->tv_sec) && (tv1->tv_usec < tv2->tv_usec)))
  52                 return (-1);
  53
  54         res->tv_sec  = tv1->tv_sec  - tv2->tv_sec;
  55         res->tv_usec = tv1->tv_usec - tv2->tv_usec;
  56
  57         assert ((res->tv_sec > 0) || ((res->tv_sec == 0) && (res->tv_usec > 0)));
  58
  59         while (res->tv_usec < 0)
  60         {
  61                 res->tv_usec += 1000000;
  62                 res->tv_sec--;
  63         }
  64         return (0);
  65 }
  66 #define LINE_LENGTH 14
  67 static int multimeter_read_value(double *value)
  68 {
  69         int retry = 3; /* sometimes we receive garbadge */
  70
  71         do
  72         {
  73                 struct timeval time_end;
  74
  75                 tcflush(fd, TCIFLUSH);
  76
  77                 if (gettimeofday (&time_end, NULL) < 0)
  78                 {
  79                         syslog (LOG_ERR, MODULE_NAME": gettimeofday failed: %s",
  80                                 strerror (errno));
  81                         return (-1);
  82                 }
  83                 time_end.tv_sec++;
  84
  85                 while (1)
  86                 {
  87                         char buf[LINE_LENGTH];
  88                         char *range;
  89                         int status;
  90                         fd_set rfds;
  91                         struct timeval timeout;
  92                         struct timeval time_now;
  93
  94                         write(fd, "D", 1);
  95
  96                         FD_ZERO(&rfds);
  97                         FD_SET(fd, &rfds);
  98
  99                         if (gettimeofday (&time_now, NULL) < 0)
 100                         {
 101                                 syslog (LOG_ERR, MODULE_NAME": gettimeofday failed: %s",
 102                                         strerror (errno));
 103                                 return (-1);
 104                         }
 105                         if (multimeter_timeval_sub (&time_end, &time_now, &timeout) == -1)
 106                                 break;
 107
 108                         status = select(fd+1, &rfds, NULL, NULL, &timeout);
 109
 110                         if (status > 0) /* usually we succeed */
 111                         {
 112                                 status = read(fd, buf, LINE_LENGTH);
 113
 114                                 if ((status < 0) && ((errno == EAGAIN) || (errno == EINTR)))
 115                                         continue;
 116
 117                                 /* Format: "DC 00.000mV  \r" */
 118                                 if (status > 0 && status == LINE_LENGTH)
 119                                 {
 120                                         *value = strtod(buf + 2, &range);
 121
 122                                         if ( range > (buf + 6) )
 123                                         {
 124                                                 range = buf + 9;
 125
 126                                                 switch ( *range )
 127                                                 {
 128                                                         case 'p': *value *= 1.0E-12; break;
 129                                                         case 'n': *value *= 1.0E-9; break;
 130                                                         case 'u': *value *= 1.0E-6; break;
 131                                                         case 'm': *value *= 1.0E-3; break;
 132                                                         case 'k': *value *= 1.0E3; break;
 133                                                         case 'M': *value *= 1.0E6; break;
 134                                                         case 'G': *value *= 1.0E9; break;
 135                                                 }
 136                                         }
 137                                         else
 138                                                 return (-1); /* Overflow */
 139
 140                                         return (0); /* value received */
 141                                 }
 142                                 else break;
 143                         }
 144                         else if (!status) /* Timeout */
 145                         {
 146                                 break;
 147                         }
 148                         else if ((status == -1) && ((errno == EAGAIN) || (errno == EINTR)))
 149                         {
 150                                 continue;
 151                         }
 152                         else /* status == -1 */
 153                         {
 154                                 syslog (LOG_ERR, MODULE_NAME": select failed: %s",
 155                                         strerror (errno));
 156                                 break;
 157                         }
 158                 }
 159         } while (--retry);
 160
 161         return (-2);  /* no value received */
 162 }
 163
 164 static void 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                                 syslog (LOG_INFO, MODULE_NAME" found (%s)", device);
 198                                 return;
 199                         }
 200                 }
 201         }
 202         syslog (LOG_ERR, MODULE_NAME" not found");
 203 }
 204 #undef LINE_LENGTH
 205
 206 static void multimeter_write (char *host, char *inst, char *val)
 207 {
 208         rrd_update_file (host, multimeter_file, val, ds_def, ds_num);
 209 }
 210 #define BUFSIZE 128
 211 static void multimeter_submit (double *value)
 212 {
 213         char buf[BUFSIZE];
 214
 215         if (snprintf (buf, BUFSIZE, "%u:%f", (unsigned int) curtime, *value) >= BUFSIZE)
 216                 return;
 217
 218         plugin_submit (MODULE_NAME, "-", buf);
 219 }
 220 #undef BUFSIZE
 221
 222 static void multimeter_read (void)
 223 {
 224         double value;
 225
 226         if (fd > -1 && !(multimeter_read_value(&value)))
 227                 multimeter_submit (&value);
 228 }
 229
 230 void module_register (void)
 231 {
 232         plugin_register (MODULE_NAME, multimeter_init, multimeter_read, multimeter_write);
 233 }
 234
 235 #undef MODULE_NAME