drivers/staging/iio/Documentation/generic_buffer.c

   1 /* Industrialio buffer test code.
   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  * This program is primarily intended as an example application.
  10  * Reads the current buffer setup from sysfs and starts a short capture
  11  * from the specified device, pretty printing the result after appropriate
  12  * conversion.
  13  *
  14  * Command line parameters
  15  * generic_buffer -n <device_name> -t <trigger_name>
  16  * If trigger name is not specified the program assumes you want a dataready
  17  * trigger associated with the device and goes looking for it.
  18  *
  19  */
  20
  21 #include <unistd.h>
  22 #include <dirent.h>
  23 #include <fcntl.h>
  24 #include <stdio.h>
  25 #include <errno.h>
  26 #include <sys/stat.h>
  27 #include <sys/dir.h>
  28 #include <linux/types.h>
  29 #include <string.h>
  30 #include <poll.h>
  31 #include <endian.h>
  32 #include "iio_utils.h"
  33
  34 /**
  35  * size_from_channelarray() - calculate the storage size of a scan
  36  * @channels: the channel info array
  37  * @num_channels: size of the channel info array
  38  *
  39  * Has the side effect of filling the channels[i].location values used
  40  * in processing the buffer output.
  41  **/
  42 int size_from_channelarray(struct iio_channel_info *channels, int num_channels)
  43 {
  44         int bytes = 0;
  45         int i = 0;
  46         while (i < num_channels) {
  47                 if (bytes % channels[i].bytes == 0)
  48                         channels[i].location = bytes;
  49                 else
  50                         channels[i].location = bytes - bytes%channels[i].bytes
  51                                 + channels[i].bytes;
  52                 bytes = channels[i].location + channels[i].bytes;
  53                 i++;
  54         }
  55         return bytes;
  56 }
  57
  58 void print2byte(int input, struct iio_channel_info *info)
  59 {
  60         /* First swap if incorrect endian */
  61
  62         if (info->be)
  63                 input = be16toh((uint16_t)input);
  64         else
  65                 input = le16toh((uint16_t)input);
  66
  67         /* shift before conversion to avoid sign extension
  68            of left aligned data */
  69         input = input >> info->shift;
  70         if (info->is_signed) {
  71                 int16_t val = input;
  72                 val &= (1 << info->bits_used) - 1;
  73                 val = (int16_t)(val << (16 - info->bits_used)) >>
  74                         (16 - info->bits_used);
  75                 printf("%05f  ", val,
  76                        (float)(val + info->offset)*info->scale);
  77         } else {
  78                 uint16_t val = input;
  79                 val &= (1 << info->bits_used) - 1;
  80                 printf("%05f ", ((float)val + info->offset)*info->scale);
  81         }
  82 }
  83 /**
  84  * process_scan() - print out the values in SI units
  85  * @data:               pointer to the start of the scan
  86  * @infoarray:          information about the channels. Note
  87  *  size_from_channelarray must have been called first to fill the
  88  *  location offsets.
  89  * @num_channels:       the number of active channels
  90  **/
  91 void process_scan(char *data,
  92                   struct iio_channel_info *infoarray,
  93                   int num_channels)
  94 {
  95         int k;
  96         for (k = 0; k < num_channels; k++)
  97                 switch (infoarray[k].bytes) {
  98                         /* only a few cases implemented so far */
  99                 case 2:
 100                         print2byte(*(uint16_t *)(data + infoarray[k].location),
 101                                    &infoarray[k]);
 102                         break;
 103                 case 8:
 104                         if (infoarray[k].is_signed) {
 105                                 int64_t val = *(int64_t *)
 106                                         (data +
 107                                          infoarray[k].location);
 108                                 if ((val >> infoarray[k].bits_used) & 1)
 109                                         val = (val & infoarray[k].mask) |
 110                                                 ~infoarray[k].mask;
 111                                 /* special case for timestamp */
 112                                 if (infoarray[k].scale == 1.0f &&
 113                                     infoarray[k].offset == 0.0f)
 114                                         printf(" %lld", val);
 115                                 else
 116                                         printf("%05f ", ((float)val +
 117                                                          infoarray[k].offset)*
 118                                                infoarray[k].scale);
 119                         }
 120                         break;
 121                 default:
 122                         break;
 123                 }
 124         printf("\n");
 125 }
 126
 127 int main(int argc, char **argv)
 128 {
 129         unsigned long num_loops = 2;
 130         unsigned long timedelay = 1000000;
 131         unsigned long buf_len = 128;
 132
 133
 134         int ret, c, i, j, toread;
 135
 136         FILE *fp_ev;
 137         int fp;
 138
 139         int num_channels;
 140         char *trigger_name = NULL, *device_name = NULL;
 141         char *dev_dir_name, *buf_dir_name;
 142
 143         int datardytrigger = 1;
 144         char *data;
 145         ssize_t read_size;
 146         int dev_num, trig_num;
 147         char *buffer_access;
 148         int scan_size;
 149         int noevents = 0;
 150         char *dummy;
 151
 152         struct iio_channel_info *infoarray;
 153
 154         while ((c = getopt(argc, argv, "l:w:c:et:n:")) != -1) {
 155                 switch (c) {
 156                 case 'n':
 157                         device_name = optarg;
 158                         break;
 159                 case 't':
 160                         trigger_name = optarg;
 161                         datardytrigger = 0;
 162                         break;
 163                 case 'e':
 164                         noevents = 1;
 165                         break;
 166                 case 'c':
 167                         num_loops = strtoul(optarg, &dummy, 10);
 168                         break;
 169                 case 'w':
 170                         timedelay = strtoul(optarg, &dummy, 10);
 171                         break;
 172                 case 'l':
 173                         buf_len = strtoul(optarg, &dummy, 10);
 174                         break;
 175                 case '?':
 176                         return -1;
 177                 }
 178         }
 179
 180         if (device_name == NULL)
 181                 return -1;
 182
 183         /* Find the device requested */
 184         dev_num = find_type_by_name(device_name, "iio:device");
 185         if (dev_num < 0) {
 186                 printf("Failed to find the %s\n", device_name);
 187                 ret = -ENODEV;
 188                 goto error_ret;
 189         }
 190         printf("iio device number being used is %d\n", dev_num);
 191
 192         asprintf(&dev_dir_name, "%siio:device%d", iio_dir, dev_num);
 193         if (trigger_name == NULL) {
 194                 /*
 195                  * Build the trigger name. If it is device associated it's
 196                  * name is <device_name>_dev[n] where n matches the device
 197                  * number found above
 198                  */
 199                 ret = asprintf(&trigger_name,
 200                                "%s-dev%d", device_name, dev_num);
 201                 if (ret < 0) {
 202                         ret = -ENOMEM;
 203                         goto error_ret;
 204                 }
 205         }
 206
 207         /* Verify the trigger exists */
 208         trig_num = find_type_by_name(trigger_name, "trigger");
 209         if (trig_num < 0) {
 210                 printf("Failed to find the trigger %s\n", trigger_name);
 211                 ret = -ENODEV;
 212                 goto error_free_triggername;
 213         }
 214         printf("iio trigger number being used is %d\n", trig_num);
 215
 216         /*
 217          * Parse the files in scan_elements to identify what channels are
 218          * present
 219          */
 220         ret = build_channel_array(dev_dir_name, &infoarray, &num_channels);
 221         if (ret) {
 222                 printf("Problem reading scan element information\n");
 223                 printf("diag %s\n", dev_dir_name);
 224                 goto error_free_triggername;
 225         }
 226
 227         /*
 228          * Construct the directory name for the associated buffer.
 229          * As we know that the lis3l02dq has only one buffer this may
 230          * be built rather than found.
 231          */
 232         ret = asprintf(&buf_dir_name,
 233                        "%siio:device%d/buffer", iio_dir, dev_num);
 234         if (ret < 0) {
 235                 ret = -ENOMEM;
 236                 goto error_free_triggername;
 237         }
 238         printf("%s %s\n", dev_dir_name, trigger_name);
 239         /* Set the device trigger to be the data rdy trigger found above */
 240         ret = write_sysfs_string_and_verify("trigger/current_trigger",
 241                                         dev_dir_name,
 242                                         trigger_name);
 243         if (ret < 0) {
 244                 printf("Failed to write current_trigger file\n");
 245                 goto error_free_buf_dir_name;
 246         }
 247
 248         /* Setup ring buffer parameters */
 249         ret = write_sysfs_int("length", buf_dir_name, buf_len);
 250         if (ret < 0)
 251                 goto error_free_buf_dir_name;
 252
 253         /* Enable the buffer */
 254         ret = write_sysfs_int("enable", buf_dir_name, 1);
 255         if (ret < 0)
 256                 goto error_free_buf_dir_name;
 257         scan_size = size_from_channelarray(infoarray, num_channels);
 258         data = malloc(scan_size*buf_len);
 259         if (!data) {
 260                 ret = -ENOMEM;
 261                 goto error_free_buf_dir_name;
 262         }
 263
 264         ret = asprintf(&buffer_access, "/dev/iio:device%d", dev_num);
 265         if (ret < 0) {
 266                 ret = -ENOMEM;
 267                 goto error_free_data;
 268         }
 269
 270         /* Attempt to open non blocking the access dev */
 271         fp = open(buffer_access, O_RDONLY | O_NONBLOCK);
 272         if (fp == -1) { /*If it isn't there make the node */
 273                 printf("Failed to open %s\n", buffer_access);
 274                 ret = -errno;
 275                 goto error_free_buffer_access;
 276         }
 277
 278         /* Wait for events 10 times */
 279         for (j = 0; j < num_loops; j++) {
 280                 if (!noevents) {
 281                         struct pollfd pfd = {
 282                                 .fd = fp,
 283                                 .events = POLLIN,
 284                         };
 285
 286                         poll(&pfd, 1, -1);
 287                         toread = buf_len;
 288
 289                 } else {
 290                         usleep(timedelay);
 291                         toread = 64;
 292                 }
 293
 294                 read_size = read(fp,
 295                                  data,
 296                                  toread*scan_size);
 297                 if (read_size == -EAGAIN) {
 298                         printf("nothing available\n");
 299                         continue;
 300                 }
 301                 for (i = 0; i < read_size/scan_size; i++)
 302                         process_scan(data + scan_size*i,
 303                                      infoarray,
 304                                      num_channels);
 305         }
 306
 307         /* Stop the ring buffer */
 308         ret = write_sysfs_int("enable", buf_dir_name, 0);
 309         if (ret < 0)
 310                 goto error_close_buffer_access;
 311
 312         /* Disconnect from the trigger - just write a dummy name.*/
 313         write_sysfs_string("trigger/current_trigger",
 314                         dev_dir_name, "NULL");
 315
 316 error_close_buffer_access:
 317         close(fp);
 318 error_free_data:
 319         free(data);
 320 error_free_buffer_access:
 321         free(buffer_access);
 322 error_free_buf_dir_name:
 323         free(buf_dir_name);
 324 error_free_triggername:
 325         if (datardytrigger)
 326                 free(trigger_name);
 327 error_ret:
 328         return ret;
 329 }