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