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 <stdlib.h>
  25 #include <dirent.h>
  26 #include <fcntl.h>
  27 #include <stdio.h>
  28 #include <errno.h>
  29 #include <sys/stat.h>
  30 #include <sys/dir.h>
  31 #include <linux/types.h>
  32 #include <string.h>
  33 #include <poll.h>
  34 #include <endian.h>
  35 #include <getopt.h>
  36 #include <inttypes.h>
  37 #include "iio_utils.h"
  38
  39 /**
  40  * size_from_channelarray() - calculate the storage size of a scan
  41  * @channels:           the channel info array
  42  * @num_channels:       number of channels
  43  *
  44  * Has the side effect of filling the channels[i].location values used
  45  * in processing the buffer output.
  46  **/
  47 int size_from_channelarray(struct iio_channel_info *channels, int num_channels)
  48 {
  49         int bytes = 0;
  50         int i = 0;
  51
  52         while (i < num_channels) {
  53                 if (bytes % channels[i].bytes == 0)
  54                         channels[i].location = bytes;
  55                 else
  56                         channels[i].location = bytes - bytes%channels[i].bytes
  57                                 + channels[i].bytes;
  58                 bytes = channels[i].location + channels[i].bytes;
  59                 i++;
  60         }
  61         return bytes;
  62 }
  63
  64 void print2byte(int input, struct iio_channel_info *info)
  65 {
  66         /* First swap if incorrect endian */
  67         if (info->be)
  68                 input = be16toh((uint16_t)input);
  69         else
  70                 input = le16toh((uint16_t)input);
  71
  72         /*
  73          * Shift before conversion to avoid sign extension
  74          * of left aligned data
  75          */
  76         input = input >> info->shift;
  77         if (info->is_signed) {
  78                 int16_t val = input;
  79
  80                 val &= (1 << info->bits_used) - 1;
  81                 val = (int16_t)(val << (16 - info->bits_used)) >>
  82                         (16 - info->bits_used);
  83                 printf("%05f ", ((float)val + info->offset)*info->scale);
  84         } else {
  85                 uint16_t val = input;
  86
  87                 val &= (1 << info->bits_used) - 1;
  88                 printf("%05f ", ((float)val + info->offset)*info->scale);
  89         }
  90 }
  91 /**
  92  * process_scan() - print out the values in SI units
  93  * @data:               pointer to the start of the scan
  94  * @channels:           information about the channels. Note
  95  *  size_from_channelarray must have been called first to fill the
  96  *  location offsets.
  97  * @num_channels:       number of channels
  98  **/
  99 void process_scan(char *data,
 100                   struct iio_channel_info *channels,
 101                   int num_channels)
 102 {
 103         int k;
 104
 105         for (k = 0; k < num_channels; k++)
 106                 switch (channels[k].bytes) {
 107                         /* only a few cases implemented so far */
 108                 case 2:
 109                         print2byte(*(uint16_t *)(data + channels[k].location),
 110                                    &channels[k]);
 111                         break;
 112                 case 4:
 113                         if (!channels[k].is_signed) {
 114                                 uint32_t val = *(uint32_t *)
 115                                         (data + channels[k].location);
 116                                 printf("%05f ", ((float)val +
 117                                                  channels[k].offset)*
 118                                        channels[k].scale);
 119
 120                         }
 121                         break;
 122                 case 8:
 123                         if (channels[k].is_signed) {
 124                                 int64_t val = *(int64_t *)
 125                                         (data +
 126                                          channels[k].location);
 127                                 if ((val >> channels[k].bits_used) & 1)
 128                                         val = (val & channels[k].mask) |
 129                                                 ~channels[k].mask;
 130                                 /* special case for timestamp */
 131                                 if (channels[k].scale == 1.0f &&
 132                                     channels[k].offset == 0.0f)
 133                                         printf("%" PRId64 " ", val);
 134                                 else
 135                                         printf("%05f ", ((float)val +
 136                                                          channels[k].offset)*
 137                                                channels[k].scale);
 138                         }
 139                         break;
 140                 default:
 141                         break;
 142                 }
 143         printf("\n");
 144 }
 145
 146 int main(int argc, char **argv)
 147 {
 148         unsigned long num_loops = 2;
 149         unsigned long timedelay = 1000000;
 150         unsigned long buf_len = 128;
 151
 152         int ret, c, i, j, toread;
 153         int fp;
 154
 155         int num_channels;
 156         char *trigger_name = NULL, *device_name = NULL;
 157         char *dev_dir_name, *buf_dir_name;
 158
 159         int datardytrigger = 1;
 160         char *data;
 161         ssize_t read_size;
 162         int dev_num, trig_num;
 163         char *buffer_access;
 164         int scan_size;
 165         int noevents = 0;
 166         int notrigger = 0;
 167         char *dummy;
 168
 169         struct iio_channel_info *channels;
 170
 171         while ((c = getopt(argc, argv, "l:w:c:et:n:g")) != -1) {
 172                 switch (c) {
 173                 case 'n':
 174                         device_name = optarg;
 175                         break;
 176                 case 't':
 177                         trigger_name = optarg;
 178                         datardytrigger = 0;
 179                         break;
 180                 case 'e':
 181                         noevents = 1;
 182                         break;
 183                 case 'c':
 184                         num_loops = strtoul(optarg, &dummy, 10);
 185                         break;
 186                 case 'w':
 187                         timedelay = strtoul(optarg, &dummy, 10);
 188                         break;
 189                 case 'l':
 190                         buf_len = strtoul(optarg, &dummy, 10);
 191                         break;
 192                 case 'g':
 193                         notrigger = 1;
 194                         break;
 195                 case '?':
 196                         return -1;
 197                 }
 198         }
 199
 200         if (device_name == NULL)
 201                 return -1;
 202
 203         /* Find the device requested */
 204         dev_num = find_type_by_name(device_name, "iio:device");
 205         if (dev_num < 0) {
 206                 printf("Failed to find the %s\n", device_name);
 207                 ret = -ENODEV;
 208                 goto error_ret;
 209         }
 210         printf("iio device number being used is %d\n", dev_num);
 211
 212         asprintf(&dev_dir_name, "%siio:device%d", iio_dir, dev_num);
 213
 214         if (!notrigger) {
 215                 if (trigger_name == NULL) {
 216                         /*
 217                          * Build the trigger name. If it is device associated
 218                          * its name is <device_name>_dev[n] where n matches
 219                          * the device number found above.
 220                          */
 221                         ret = asprintf(&trigger_name,
 222                                        "%s-dev%d", device_name, dev_num);
 223                         if (ret < 0) {
 224                                 ret = -ENOMEM;
 225                                 goto error_ret;
 226                         }
 227                 }
 228
 229                 /* Verify the trigger exists */
 230                 trig_num = find_type_by_name(trigger_name, "trigger");
 231                 if (trig_num < 0) {
 232                         printf("Failed to find the trigger %s\n", trigger_name);
 233                         ret = -ENODEV;
 234                         goto error_free_triggername;
 235                 }
 236                 printf("iio trigger number being used is %d\n", trig_num);
 237         } else
 238                 printf("trigger-less mode selected\n");
 239
 240         /*
 241          * Parse the files in scan_elements to identify what channels are
 242          * present
 243          */
 244         ret = build_channel_array(dev_dir_name, &channels, &num_channels);
 245         if (ret) {
 246                 printf("Problem reading scan element information\n");
 247                 printf("diag %s\n", dev_dir_name);
 248                 goto error_free_triggername;
 249         }
 250
 251         /*
 252          * Construct the directory name for the associated buffer.
 253          * As we know that the lis3l02dq has only one buffer this may
 254          * be built rather than found.
 255          */
 256         ret = asprintf(&buf_dir_name,
 257                        "%siio:device%d/buffer", iio_dir, dev_num);
 258         if (ret < 0) {
 259                 ret = -ENOMEM;
 260                 goto error_free_triggername;
 261         }
 262
 263         if (!notrigger) {
 264                 printf("%s %s\n", dev_dir_name, trigger_name);
 265                 /* Set the device trigger to be the data ready trigger found
 266                  * above */
 267                 ret = write_sysfs_string_and_verify("trigger/current_trigger",
 268                                                     dev_dir_name,
 269                                                     trigger_name);
 270                 if (ret < 0) {
 271                         printf("Failed to write current_trigger file\n");
 272                         goto error_free_buf_dir_name;
 273                 }
 274         }
 275
 276         /* Setup ring buffer parameters */
 277         ret = write_sysfs_int("length", buf_dir_name, buf_len);
 278         if (ret < 0)
 279                 goto error_free_buf_dir_name;
 280
 281         /* Enable the buffer */
 282         ret = write_sysfs_int("enable", buf_dir_name, 1);
 283         if (ret < 0)
 284                 goto error_free_buf_dir_name;
 285         scan_size = size_from_channelarray(channels, num_channels);
 286         data = malloc(scan_size*buf_len);
 287         if (!data) {
 288                 ret = -ENOMEM;
 289                 goto error_free_buf_dir_name;
 290         }
 291
 292         ret = asprintf(&buffer_access, "/dev/iio:device%d", dev_num);
 293         if (ret < 0) {
 294                 ret = -ENOMEM;
 295                 goto error_free_data;
 296         }
 297
 298         /* Attempt to open non blocking the access dev */
 299         fp = open(buffer_access, O_RDONLY | O_NONBLOCK);
 300         if (fp == -1) { /* If it isn't there make the node */
 301                 printf("Failed to open %s\n", buffer_access);
 302                 ret = -errno;
 303                 goto error_free_buffer_access;
 304         }
 305
 306         /* Wait for events 10 times */
 307         for (j = 0; j < num_loops; j++) {
 308                 if (!noevents) {
 309                         struct pollfd pfd = {
 310                                 .fd = fp,
 311                                 .events = POLLIN,
 312                         };
 313
 314                         poll(&pfd, 1, -1);
 315                         toread = buf_len;
 316
 317                 } else {
 318                         usleep(timedelay);
 319                         toread = 64;
 320                 }
 321
 322                 read_size = read(fp,
 323                                  data,
 324                                  toread*scan_size);
 325                 if (read_size < 0) {
 326                         if (errno == -EAGAIN) {
 327                                 printf("nothing available\n");
 328                                 continue;
 329                         } else
 330                                 break;
 331                 }
 332                 for (i = 0; i < read_size/scan_size; i++)
 333                         process_scan(data + scan_size*i,
 334                                      channels,
 335                                      num_channels);
 336         }
 337
 338         /* Stop the buffer */
 339         ret = write_sysfs_int("enable", buf_dir_name, 0);
 340         if (ret < 0)
 341                 goto error_close_buffer_access;
 342
 343         if (!notrigger)
 344                 /* Disconnect the trigger - just write a dummy name. */
 345                 write_sysfs_string("trigger/current_trigger",
 346                                    dev_dir_name, "NULL");
 347
 348 error_close_buffer_access:
 349         close(fp);
 350 error_free_data:
 351         free(data);
 352 error_free_buffer_access:
 353         free(buffer_access);
 354 error_free_buf_dir_name:
 355         free(buf_dir_name);
 356 error_free_triggername:
 357         if (datardytrigger)
 358                 free(trigger_name);
 359 error_ret:
 360         return ret;
 361 }