drivers/staging/iio/Documentation/lis3l02dqbuffersimple.c

   1 /* Industrialio test ring buffer with a lis3l02dq acceleromter
   2  *
   3  * Copyright (c) 2008 Jonathan Cameron
   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 version 2 as published by
   7  * the Free Software Foundation.
   8  *
   9  * Assumes suitable udev rules are used to create the dev nodes as named here.
  10  */
  11
  12 #include <dirent.h>
  13 #include <fcntl.h>
  14 #include <stdio.h>
  15 #include <errno.h>
  16 #include <stdint.h>
  17 #include <sys/types.h>
  18 #include <sys/stat.h>
  19 #include <sys/dir.h>
  20
  21 #include <linux/types.h>
  22 #include <dirent.h>
  23 #include "iio_util.h"
  24
  25 static const char *ring_access = "/dev/iio/lis3l02dq_ring_access";
  26 static const char *ring_event = "/dev/iio/lis3l02dq_ring_event";
  27 static const char *device_name = "lis3l02dq";
  28 static const char *trigger_name = "lis3l02dq-dev0";
  29 static int NumVals = 3;
  30 static int scan_ts = 1;
  31 static int RingLength = 128;
  32
  33 /*
  34  * Could get this from ring bps, but only after starting the ring
  35  * which is a bit late for it to be useful
  36  */
  37 int size_from_scanmode(int numVals, int timestamp)
  38 {
  39         if (numVals && timestamp)
  40                 return 16;
  41         else if (timestamp)
  42                 return 8;
  43         else
  44                 return numVals*2;
  45 }
  46
  47 int main(int argc, char **argv)
  48 {
  49         int i, j, k, toread;
  50         FILE *fp_ev;
  51         int fp;
  52         char *data;
  53         size_t read_size;
  54         struct iio_event_data dat;
  55
  56         char    *BaseDirectoryName,
  57                 *TriggerDirectoryName,
  58                 *RingBufferDirectoryName;
  59
  60         BaseDirectoryName = find_type_by_name(device_name, "device");
  61         if (BaseDirectoryName == NULL) {
  62                 printf("Failed to find the %s \n", device_name);
  63                 return -1;
  64         }
  65         TriggerDirectoryName = find_type_by_name(trigger_name, "trigger");
  66         if (TriggerDirectoryName == NULL) {
  67                 printf("Failed to find the %s\n", trigger_name);
  68                 return -1;
  69         }
  70         RingBufferDirectoryName = find_ring_subelement(BaseDirectoryName,
  71                                                        "ring_buffer");
  72         if (RingBufferDirectoryName == NULL) {
  73                 printf("Failed to find ring buffer\n");
  74                 return -1;
  75         }
  76
  77         if (write_sysfs_string_and_verify("trigger/current_trigger",
  78                                           BaseDirectoryName,
  79                                           (char *)trigger_name) < 0) {
  80                 printf("Failed to write current_trigger file \n");
  81                 return -1;
  82         }
  83
  84         /* Setup ring buffer parameters */
  85         if (write_sysfs_int("length", RingBufferDirectoryName,
  86                             RingLength) < 0) {
  87                 printf("Failed to open the ring buffer length file \n");
  88                 return -1;
  89         }
  90
  91         /* Enable the ring buffer */
  92         if (write_sysfs_int("ring_enable", RingBufferDirectoryName, 1) < 0) {
  93                 printf("Failed to open the ring buffer control file \n");
  94                 return -1;
  95         };
  96
  97         data = malloc(size_from_scanmode(NumVals, scan_ts)*RingLength);
  98         if (!data) {
  99                 printf("Could not allocate space for usespace data store\n");
 100                 return -1;
 101         }
 102
 103         /* Attempt to open non blocking the access dev */
 104         fp = open(ring_access, O_RDONLY | O_NONBLOCK);
 105         if (fp == -1) { /*If it isn't there make the node */
 106                 printf("Failed to open %s\n", ring_access);
 107                 return -1;
 108         }
 109         /* Attempt to open the event access dev (blocking this time) */
 110         fp_ev = fopen(ring_event, "rb");
 111         if (fp_ev == NULL) {
 112                 printf("Failed to open %s\n", ring_event);
 113                 return -1;
 114         }
 115
 116         /* Wait for events 10 times */
 117         for (j = 0; j < 10; j++) {
 118                 read_size = fread(&dat, 1, sizeof(struct iio_event_data),
 119                                   fp_ev);
 120                 switch (dat.id) {
 121                 case IIO_EVENT_CODE_RING_100_FULL:
 122                         toread = RingLength;
 123                         break;
 124                 case IIO_EVENT_CODE_RING_75_FULL:
 125                         toread = RingLength*3/4;
 126                         break;
 127                 case IIO_EVENT_CODE_RING_50_FULL:
 128                         toread = RingLength/2;
 129                         break;
 130                 default:
 131                         printf("Unexpecteded event code\n");
 132                         continue;
 133                 }
 134                 read_size = read(fp,
 135                                  data,
 136                                  toread*size_from_scanmode(NumVals, scan_ts));
 137                 if (read_size == -EAGAIN) {
 138                         printf("nothing available \n");
 139                         continue;
 140                 }
 141
 142                 for (i = 0;
 143                      i < read_size/size_from_scanmode(NumVals, scan_ts);
 144                      i++) {
 145                         for (k = 0; k < NumVals; k++) {
 146                                 __s16 val = *(__s16 *)(&data[i*size_from_scanmode(NumVals, scan_ts)
 147                                                              + (k)*2]);
 148                                 printf("%05d ", val);
 149                         }
 150                         printf(" %lld\n",
 151                                *(__s64 *)(&data[(i+1)*size_from_scanmode(NumVals, scan_ts)
 152                                                 - sizeof(__s64)]));
 153                 }
 154         }
 155
 156         /* Stop the ring buffer */
 157         if (write_sysfs_int("ring_enable", RingBufferDirectoryName, 0) < 0) {
 158                 printf("Failed to open the ring buffer control file \n");
 159                 return -1;
 160         };
 161
 162         /* Disconnect from the trigger - writing something that doesn't exist.*/
 163         write_sysfs_string_and_verify("trigger/current_trigger",
 164                                       BaseDirectoryName, "NULL");
 165         free(BaseDirectoryName);
 166         free(TriggerDirectoryName);
 167         free(RingBufferDirectoryName);
 168         free(data);
 169
 170         return 0;
 171 }