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 #define _GNU_SOURCE
  22
  23 #include <unistd.h>
  24 #include <dirent.h>
  25 #include <fcntl.h>
  26 #include <stdio.h>
  27 #include <errno.h>
  28 #include <sys/stat.h>
  29 #include <sys/dir.h>
  30 #include <linux/types.h>
  31 #include <string.h>
  32 #include <poll.h>
  33 #include <endian.h>
  34 #include <getopt.h>
  35 #include <inttypes.h>
  36 #include "iio_utils.h"
  37
  38 /**
  39  * size_from_channelarray() - calculate the storage size of a scan
  40  * @channels:           the channel info array
  41  * @num_channels:       number of channels
  42  *
  43  * Has the side effect of filling the channels[i].location values used
  44  * in processing the buffer output.
  45  **/
  46 int size_from_channelarray(struct iio_channel_info *channels, int num_channels)
  47 {
  48         int bytes = 0;
  49         int i = 0;
  50
  51         while (i < num_channels) {
  52                 if (bytes % channels[i].bytes == 0)
  53                         channels[i].location = bytes;
  54                 else
  55                         channels[i].location = bytes - bytes%channels[i].bytes
  56                                 + channels[i].bytes;
  57                 bytes = channels[i].location + channels[i].bytes;
  58                 i++;
  59         }
  60         return bytes;
  61 }
  62
  63 void print2byte(int input, struct iio_channel_info *info)
  64 {
  65         /* First swap if incorrect endian */
  66         if (info->be)
  67                 input = be16toh((uint16_t)input);
  68         else
  69                 input = le16toh((uint16_t)input);
  70
  71         /*
  72          * Shift before conversion to avoid sign extension
  73          * of left aligned data
  74          */
  75         input = input >> info->shift;
  76         if (info->is_signed) {
  77                 int16_t val = input;
  78
  79                 val &= (1 << info->bits_used) - 1;
  80                 val = (int16_t)(val << (16 - info->bits_used)) >>
  81                         (16 - info->bits_used);
  82                 printf("%05f ", ((float)val + info->offset)*info->scale);
  83         } else {
  84                 uint16_t val = input;
  85
  86                 val &= (1 << info->bits_used) - 1;
  87                 printf("%05f ", ((float)val + info->offset)*info->scale);
  88         }
  89 }
  90 /**
  91  * process_scan() - print out the values in SI units
  92  * @data:               pointer to the start of the scan
  93  * @channels:           information about the channels. Note
  94  *  size_from_channelarray must have been called first to fill the
  95  *  location offsets.
  96  * @num_channels:       number of channels
  97  **/
  98 void process_scan(char *data,
  99                   struct iio_channel_info *channels,
 100                   int num_channels)
 101 {
 102         int k;
 103
 104         for (k = 0; k < num_channels; k++)
 105                 switch (channels[k].bytes) {
 106                         /* only a few cases implemented so far */
 107                 case 2:
 108                         print2byte(*(uint16_t *)(data + channels[k].location),
 109                                    &channels[k]);
 110                         break;
 111                 case 4:
 112                         if (!channels[k].is_signed) {
 113                                 uint32_t val = *(uint32_t *)
 114                                         (data + channels[k].location);
 115                                 printf("%05f ", ((float)val +
 116                                                  channels[k].offset)*
 117                                        channels[k].scale);
 118
 119                         }
 120                         break;
 121                 case 8:
 122                         if (channels[k].is_signed) {
 123                                 int64_t val = *(int64_t *)
 124                                         (data +
 125                                          channels[k].location);
 126                                 if ((val >> channels[k].bits_used) & 1)
 127                                         val = (val & channels[k].mask) |
 128                                                 ~channels[k].mask;
 129                                 /* special case for timestamp */
 130                                 if (channels[k].scale == 1.0f &&
 131                                     channels[k].offset == 0.0f)
 132                                         printf("%" PRId64 " ", val);
 133                                 else
 134                                         printf("%05f ", ((float)val +
 135                                                          channels[k].offset)*
 136                                                channels[k].scale);
 137                         }
 138                         break;
 139                 default:
 140                         break;
 141                 }
 142         printf("\n");
 143 }
 144
 145 int main(int argc, char **argv)
 146 {
 147         unsigned long num_loops = 2;
 148         unsigned long timedelay = 1000000;
 149         unsigned long buf_len = 128;
 150
 151         int ret, c, i, j, toread;
 152         int fp;
 153
 154         int num_channels;
 155         char *trigger_name = NULL, *device_name = NULL;
 156         char *dev_dir_name, *buf_dir_name;
 157
 158         int datardytrigger = 1;
 159         char *data;
 160         ssize_t read_size;
 161         int dev_num, trig_num;
 162         char *buffer_access;
 163         int scan_size;
 164         int noevents = 0;
 165         int notrigger = 0;
 166         char *dummy;
 167
 168         struct iio_channel_info *channels;
 169
 170         while ((c = getopt(argc, argv, "l:w:c:et:n:g")) != -1) {
 171                 switch (c) {
 172                 case 'n':
 173                         device_name = optarg;
 174                         break;
 175                 case 't':
 176                         trigger_name = optarg;
 177                         datardytrigger = 0;
 178                         break;
 179                 case 'e':
 180                         noevents = 1;
 181                         break;
 182                 case 'c':
 183                         num_loops = strtoul(optarg, &dummy, 10);
 184                         break;
 185                 case 'w':
 186                         timedelay = strtoul(optarg, &dummy, 10);
 187                         break;
 188                 case 'l':
 189                         buf_len = strtoul(optarg, &dummy, 10);
 190                         break;
 191                 case 'g':
 192                         notrigger = 1;
 193                         break;
 194                 case '?':
 195                         return -1;
 196                 }
 197         }
 198
 199         if (device_name == NULL)
 200                 return -1;
 201
 202         /* Find the device requested */
 203         dev_num = find_type_by_name(device_name, "iio:device");
 204         if (dev_num < 0) {
 205                 printf("Failed to find the %s\n", device_name);
 206                 ret = -ENODEV;
 207                 goto error_ret;
 208         }
 209         printf("iio device number being used is %d\n", dev_num);
 210
 211         asprintf(&dev_dir_name, "%siio:device%d", iio_dir, dev_num);
 212
 213         if (!notrigger) {
 214                 if (trigger_name == NULL) {
 215                         /*
 216                          * Build the trigger name. If it is device associated
 217                          * its name is <device_name>_dev[n] where n matches
 218                          * the device number found above.
 219                          */
 220                         ret = asprintf(&trigger_name,
 221                                        "%s-dev%d", device_name, dev_num);
 222                         if (ret < 0) {
 223                                 ret = -ENOMEM;
 224                                 goto error_ret;
 225                         }
 226                 }
 227
 228                 /* Verify the trigger exists */
 229                 trig_num = find_type_by_name(trigger_name, "trigger");
 230                 if (trig_num < 0) {
 231                         printf("Failed to find the trigger %s\n", trigger_name);
 232                         ret = -ENODEV;
 233                         goto error_free_triggername;
 234                 }
 235                 printf("iio trigger number being used is %d\n", trig_num);
 236         } else
 237                 printf("trigger-less mode selected\n");
 238
 239         /*
 240          * Parse the files in scan_elements to identify what channels are
 241          * present
 242          */
 243         ret = build_channel_array(dev_dir_name, &channels, &num_channels);
 244         if (ret) {
 245                 printf("Problem reading scan element information\n");
 246                 printf("diag %s\n", dev_dir_name);
 247                 goto error_free_triggername;
 248         }
 249
 250         /*
 251          * Construct the directory name for the associated buffer.
 252          * As we know that the lis3l02dq has only one buffer this may
 253          * be built rather than found.
 254          */
 255         ret = asprintf(&buf_dir_name,
 256                        "%siio:device%d/buffer", iio_dir, dev_num);
 257         if (ret < 0) {
 258                 ret = -ENOMEM;
 259                 goto error_free_triggername;
 260         }
 261
 262         if (!notrigger) {
 263                 printf("%s %s\n", dev_dir_name, trigger_name);
 264                 /* Set the device trigger to be the data ready trigger found
 265                  * above */
 266                 ret = write_sysfs_string_and_verify("trigger/current_trigger",
 267                                                     dev_dir_name,
 268                                                     trigger_name);
 269                 if (ret < 0) {
 270                         printf("Failed to write current_trigger file\n");
 271                         goto error_free_buf_dir_name;
 272                 }
 273         }
 274
 275         /* Setup ring buffer parameters */
 276         ret = write_sysfs_int("length", buf_dir_name, buf_len);
 277         if (ret < 0)
 278                 goto error_free_buf_dir_name;
 279
 280         /* Enable the buffer */
 281         ret = write_sysfs_int("enable", buf_dir_name, 1);
 282         if (ret < 0)
 283                 goto error_free_buf_dir_name;
 284         scan_size = size_from_channelarray(channels, num_channels);
 285         data = malloc(scan_size*buf_len);
 286         if (!data) {
 287                 ret = -ENOMEM;
 288                 goto error_free_buf_dir_name;
 289         }
 290
 291         ret = asprintf(&buffer_access, "/dev/iio:device%d", dev_num);
 292         if (ret < 0) {
 293                 ret = -ENOMEM;
 294                 goto error_free_data;
 295         }
 296
 297         /* Attempt to open non blocking the access dev */
 298         fp = open(buffer_access, O_RDONLY | O_NONBLOCK);
 299         if (fp == -1) { /* If it isn't there make the node */
 300                 printf("Failed to open %s\n", buffer_access);
 301                 ret = -errno;
 302                 goto error_free_buffer_access;
 303         }
 304
 305         /* Wait for events 10 times */
 306         for (j = 0; j < num_loops; j++) {
 307                 if (!noevents) {
 308                         struct pollfd pfd = {
 309                                 .fd = fp,
 310                                 .events = POLLIN,
 311                         };
 312
 313                         poll(&pfd, 1, -1);
 314                         toread = buf_len;
 315
 316                 } else {
 317                         usleep(timedelay);
 318                         toread = 64;
 319                 }
 320
 321                 read_size = read(fp,
 322                                  data,
 323                                  toread*scan_size);
 324                 if (read_size < 0) {
 325                         if (errno == -EAGAIN) {
 326                                 printf("nothing available\n");
 327                                 continue;
 328                         } else
 329                                 break;
 330                 }
 331                 for (i = 0; i < read_size/scan_size; i++)
 332                         process_scan(data + scan_size*i,
 333                                      channels,
 334                                      num_channels);
 335         }
 336
 337         /* Stop the buffer */
 338         ret = write_sysfs_int("enable", buf_dir_name, 0);
 339         if (ret < 0)
 340                 goto error_close_buffer_access;
 341
 342         if (!notrigger)
 343                 /* Disconnect the trigger - just write a dummy name. */
 344                 write_sysfs_string("trigger/current_trigger",
 345                                    dev_dir_name, "NULL");
 346
 347 error_close_buffer_access:
 348         close(fp);
 349 error_free_data:
 350         free(data);
 351 error_free_buffer_access:
 352         free(buffer_access);
 353 error_free_buf_dir_name:
 354         free(buf_dir_name);
 355 error_free_triggername:
 356         if (datardytrigger)
 357                 free(trigger_name);
 358 error_ret:
 359         return ret;
 360 }