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