tools/iio/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 <stdlib.h>
  23 #include <dirent.h>
  24 #include <fcntl.h>
  25 #include <stdio.h>
  26 #include <errno.h>
  27 #include <sys/stat.h>
  28 #include <sys/dir.h>
  29 #include <linux/types.h>
  30 #include <string.h>
  31 #include <poll.h>
  32 #include <endian.h>
  33 #include <getopt.h>
  34 #include <inttypes.h>
  35 #include "iio_utils.h"
  36
  37 /**
  38  * size_from_channelarray() - calculate the storage size of a scan
  39  * @channels:           the channel info array
  40  * @num_channels:       number of channels
  41  *
  42  * Has the side effect of filling the channels[i].location values used
  43  * in processing the buffer output.
  44  **/
  45 int size_from_channelarray(struct iio_channel_info *channels, int num_channels)
  46 {
  47         int bytes = 0;
  48         int i = 0;
  49
  50         while (i < num_channels) {
  51                 if (bytes % channels[i].bytes == 0)
  52                         channels[i].location = bytes;
  53                 else
  54                         channels[i].location = bytes - bytes%channels[i].bytes
  55                                 + channels[i].bytes;
  56                 bytes = channels[i].location + channels[i].bytes;
  57                 i++;
  58         }
  59         return bytes;
  60 }
  61
  62 void print2byte(int input, struct iio_channel_info *info)
  63 {
  64         /* First swap if incorrect endian */
  65         if (info->be)
  66                 input = be16toh((uint16_t)input);
  67         else
  68                 input = le16toh((uint16_t)input);
  69
  70         /*
  71          * Shift before conversion to avoid sign extension
  72          * of left aligned data
  73          */
  74         input = input >> info->shift;
  75         if (info->is_signed) {
  76                 int16_t val = input;
  77
  78                 val &= (1 << info->bits_used) - 1;
  79                 val = (int16_t)(val << (16 - info->bits_used)) >>
  80                         (16 - info->bits_used);
  81                 printf("%05f ", ((float)val + info->offset)*info->scale);
  82         } else {
  83                 uint16_t val = input;
  84
  85                 val &= (1 << info->bits_used) - 1;
  86                 printf("%05f ", ((float)val + info->offset)*info->scale);
  87         }
  88 }
  89 /**
  90  * process_scan() - print out the values in SI units
  91  * @data:               pointer to the start of the scan
  92  * @channels:           information about the channels. Note
  93  *  size_from_channelarray must have been called first to fill the
  94  *  location offsets.
  95  * @num_channels:       number of channels
  96  **/
  97 void process_scan(char *data,
  98                   struct iio_channel_info *channels,
  99                   int num_channels)
 100 {
 101         int k;
 102
 103         for (k = 0; k < num_channels; k++)
 104                 switch (channels[k].bytes) {
 105                         /* only a few cases implemented so far */
 106                 case 2:
 107                         print2byte(*(uint16_t *)(data + channels[k].location),
 108                                    &channels[k]);
 109                         break;
 110                 case 4:
 111                         if (!channels[k].is_signed) {
 112                                 uint32_t val = *(uint32_t *)
 113                                         (data + channels[k].location);
 114                                 printf("%05f ", ((float)val +
 115                                                  channels[k].offset)*
 116                                        channels[k].scale);
 117
 118                         }
 119                         break;
 120                 case 8:
 121                         if (channels[k].is_signed) {
 122                                 int64_t val = *(int64_t *)
 123                                         (data +
 124                                          channels[k].location);
 125                                 if ((val >> channels[k].bits_used) & 1)
 126                                         val = (val & channels[k].mask) |
 127                                                 ~channels[k].mask;
 128                                 /* special case for timestamp */
 129                                 if (channels[k].scale == 1.0f &&
 130                                     channels[k].offset == 0.0f)
 131                                         printf("%" PRId64 " ", val);
 132                                 else
 133                                         printf("%05f ", ((float)val +
 134                                                          channels[k].offset)*
 135                                                channels[k].scale);
 136                         }
 137                         break;
 138                 default:
 139                         break;
 140                 }
 141         printf("\n");
 142 }
 143
 144 int main(int argc, char **argv)
 145 {
 146         unsigned long num_loops = 2;
 147         unsigned long timedelay = 1000000;
 148         unsigned long buf_len = 128;
 149
 150         int ret, c, i, j, toread;
 151         int fp;
 152
 153         int num_channels;
 154         char *trigger_name = NULL, *device_name = NULL;
 155         char *dev_dir_name, *buf_dir_name;
 156
 157         int datardytrigger = 1;
 158         char *data;
 159         ssize_t read_size;
 160         int dev_num, trig_num;
 161         char *buffer_access;
 162         int scan_size;
 163         int noevents = 0;
 164         int notrigger = 0;
 165         char *dummy;
 166
 167         struct iio_channel_info *channels;
 168
 169         while ((c = getopt(argc, argv, "l:w:c:et:n:g")) != -1) {
 170                 switch (c) {
 171                 case 'n':
 172                         device_name = optarg;
 173                         break;
 174                 case 't':
 175                         trigger_name = optarg;
 176                         datardytrigger = 0;
 177                         break;
 178                 case 'e':
 179                         noevents = 1;
 180                         break;
 181                 case 'c':
 182                         num_loops = strtoul(optarg, &dummy, 10);
 183                         break;
 184                 case 'w':
 185                         timedelay = strtoul(optarg, &dummy, 10);
 186                         break;
 187                 case 'l':
 188                         buf_len = strtoul(optarg, &dummy, 10);
 189                         break;
 190                 case 'g':
 191                         notrigger = 1;
 192                         break;
 193                 case '?':
 194                         return -1;
 195                 }
 196         }
 197
 198         if (device_name == NULL)
 199                 return -1;
 200
 201         /* Find the device requested */
 202         dev_num = find_type_by_name(device_name, "iio:device");
 203         if (dev_num < 0) {
 204                 printf("Failed to find the %s\n", device_name);
 205                 ret = -ENODEV;
 206                 goto error_ret;
 207         }
 208         printf("iio device number being used is %d\n", dev_num);
 209
 210         asprintf(&dev_dir_name, "%siio:device%d", iio_dir, dev_num);
 211
 212         if (!notrigger) {
 213                 if (trigger_name == NULL) {
 214                         /*
 215                          * Build the trigger name. If it is device associated
 216                          * its name is <device_name>_dev[n] where n matches
 217                          * the device number found above.
 218                          */
 219                         ret = asprintf(&trigger_name,
 220                                        "%s-dev%d", device_name, dev_num);
 221                         if (ret < 0) {
 222                                 ret = -ENOMEM;
 223                                 goto error_ret;
 224                         }
 225                 }
 226
 227                 /* Verify the trigger exists */
 228                 trig_num = find_type_by_name(trigger_name, "trigger");
 229                 if (trig_num < 0) {
 230                         printf("Failed to find the trigger %s\n", trigger_name);
 231                         ret = -ENODEV;
 232                         goto error_free_triggername;
 233                 }
 234                 printf("iio trigger number being used is %d\n", trig_num);
 235         } else
 236                 printf("trigger-less mode selected\n");
 237
 238         /*
 239          * Parse the files in scan_elements to identify what channels are
 240          * present
 241          */
 242         ret = build_channel_array(dev_dir_name, &channels, &num_channels);
 243         if (ret) {
 244                 printf("Problem reading scan element information\n");
 245                 printf("diag %s\n", dev_dir_name);
 246                 goto error_free_triggername;
 247         }
 248
 249         /*
 250          * Construct the directory name for the associated buffer.
 251          * As we know that the lis3l02dq has only one buffer this may
 252          * be built rather than found.
 253          */
 254         ret = asprintf(&buf_dir_name,
 255                        "%siio:device%d/buffer", iio_dir, dev_num);
 256         if (ret < 0) {
 257                 ret = -ENOMEM;
 258                 goto error_free_triggername;
 259         }
 260
 261         if (!notrigger) {
 262                 printf("%s %s\n", dev_dir_name, trigger_name);
 263                 /* Set the device trigger to be the data ready trigger found
 264                  * above */
 265                 ret = write_sysfs_string_and_verify("trigger/current_trigger",
 266                                                     dev_dir_name,
 267                                                     trigger_name);
 268                 if (ret < 0) {
 269                         printf("Failed to write current_trigger file\n");
 270                         goto error_free_buf_dir_name;
 271                 }
 272         }
 273
 274         /* Setup ring buffer parameters */
 275         ret = write_sysfs_int("length", buf_dir_name, buf_len);
 276         if (ret < 0)
 277                 goto error_free_buf_dir_name;
 278
 279         /* Enable the buffer */
 280         ret = write_sysfs_int("enable", buf_dir_name, 1);
 281         if (ret < 0)
 282                 goto error_free_buf_dir_name;
 283         scan_size = size_from_channelarray(channels, num_channels);
 284         data = malloc(scan_size*buf_len);
 285         if (!data) {
 286                 ret = -ENOMEM;
 287                 goto error_free_buf_dir_name;
 288         }
 289
 290         ret = asprintf(&buffer_access, "/dev/iio:device%d", dev_num);
 291         if (ret < 0) {
 292                 ret = -ENOMEM;
 293                 goto error_free_data;
 294         }
 295
 296         /* Attempt to open non blocking the access dev */
 297         fp = open(buffer_access, O_RDONLY | O_NONBLOCK);
 298         if (fp == -1) { /* If it isn't there make the node */
 299                 printf("Failed to open %s\n", buffer_access);
 300                 ret = -errno;
 301                 goto error_free_buffer_access;
 302         }
 303
 304         /* Wait for events 10 times */
 305         for (j = 0; j < num_loops; j++) {
 306                 if (!noevents) {
 307                         struct pollfd pfd = {
 308                                 .fd = fp,
 309                                 .events = POLLIN,
 310                         };
 311
 312                         poll(&pfd, 1, -1);
 313                         toread = buf_len;
 314
 315                 } else {
 316                         usleep(timedelay);
 317                         toread = 64;
 318                 }
 319
 320                 read_size = read(fp,
 321                                  data,
 322                                  toread*scan_size);
 323                 if (read_size < 0) {
 324                         if (errno == -EAGAIN) {
 325                                 printf("nothing available\n");
 326                                 continue;
 327                         } else
 328                                 break;
 329                 }
 330                 for (i = 0; i < read_size/scan_size; i++)
 331                         process_scan(data + scan_size*i,
 332                                      channels,
 333                                      num_channels);
 334         }
 335
 336         /* Stop the buffer */
 337         ret = write_sysfs_int("enable", buf_dir_name, 0);
 338         if (ret < 0)
 339                 goto error_close_buffer_access;
 340
 341         if (!notrigger)
 342                 /* Disconnect the trigger - just write a dummy name. */
 343                 write_sysfs_string("trigger/current_trigger",
 344                                    dev_dir_name, "NULL");
 345
 346 error_close_buffer_access:
 347         close(fp);
 348 error_free_data:
 349         free(data);
 350 error_free_buffer_access:
 351         free(buffer_access);
 352 error_free_buf_dir_name:
 353         free(buf_dir_name);
 354 error_free_triggername:
 355         if (datardytrigger)
 356                 free(trigger_name);
 357 error_ret:
 358         return ret;
 359 }