control.c

   1 /*
   2  * Copyright (C) 2014 Intel Corporation.
   3  */
   4
   5 #include <stdlib.h>
   6 #include <ctype.h>
   7 #include <fcntl.h>
   8 #include <pthread.h>
   9 #include <time.h>
  10 #include <sys/epoll.h>
  11 #include <sys/socket.h>
  12 #include <utils/Log.h>
  13 #include <hardware/sensors.h>
  14 #include "control.h"
  15 #include "enumeration.h"
  16 #include "utils.h"
  17 #include "transform.h"
  18 #include "calibration.h"
  19 #include "description.h"
  20
  21 /* Currently active sensors count, per device */
  22 static int poll_sensors_per_dev[MAX_DEVICES];   /* poll-mode sensors */
  23 static int trig_sensors_per_dev[MAX_DEVICES];   /* trigger, event based */
  24
  25 static int device_fd[MAX_DEVICES];   /* fd on the /dev/iio:deviceX file */
  26
  27 static int poll_fd; /* epoll instance covering all enabled sensors */
  28
  29 static int active_poll_sensors; /* Number of enabled poll-mode sensors */
  30
  31 int64_t ts_delta; /* delta between SystemClock.getNanos and our timestamp */
  32
  33 /* We use pthread condition variables to get worker threads out of sleep */
  34 static pthread_condattr_t thread_cond_attr      [MAX_SENSORS];
  35 static pthread_cond_t     thread_release_cond   [MAX_SENSORS];
  36 static pthread_mutex_t    thread_release_mutex  [MAX_SENSORS];
  37
  38 /*
  39  * We associate tags to each of our poll set entries. These tags have the
  40  * following values:
  41  * - a iio device number if the fd is a iio character device fd
  42  * - THREAD_REPORT_TAG_BASE + sensor handle if the fd is the receiving end of a
  43  *   pipe used by a sysfs data acquisition thread
  44  *  */
  45 #define THREAD_REPORT_TAG_BASE  0x00010000
  46
  47 #define ENABLE_BUFFER_RETRIES 10
  48 #define ENABLE_BUFFER_RETRY_DELAY_MS 10
  49
  50 static int enable_buffer(int dev_num, int enabled)
  51 {
  52         char sysfs_path[PATH_MAX];
  53         int ret, retries, millisec;
  54         struct timespec req = {0};
  55
  56         retries = ENABLE_BUFFER_RETRIES;
  57         millisec = ENABLE_BUFFER_RETRY_DELAY_MS;
  58         req.tv_sec = 0;
  59         req.tv_nsec = millisec * 1000000L;
  60
  61         sprintf(sysfs_path, ENABLE_PATH, dev_num);
  62
  63         while (retries--) {
  64                 /* Low level, non-multiplexed, enable/disable routine */
  65                 ret = sysfs_write_int(sysfs_path, enabled);
  66                 if (ret > 0)
  67                         break;
  68
  69                 ALOGE("Failed enabling buffer, retrying");
  70                 nanosleep(&req, (struct timespec *)NULL);
  71         }
  72
  73         if (ret < 0) {
  74                 ALOGE("Could not enable buffer\n");
  75                 return -EIO;
  76         }
  77
  78         return 0;
  79 }
  80
  81
  82 static int setup_trigger (int s, const char* trigger_val)
  83 {
  84         char sysfs_path[PATH_MAX];
  85         int ret = -1, attempts = 5;
  86
  87         sprintf(sysfs_path, TRIGGER_PATH, sensor_info[s].dev_num);
  88
  89         if (trigger_val[0] != '\n')
  90                 ALOGI("Setting S%d (%s) trigger to %s\n", s,
  91                         sensor_info[s].friendly_name, trigger_val);
  92
  93         while (ret == -1 && attempts) {
  94                 ret = sysfs_write_str(sysfs_path, trigger_val);
  95                 attempts--;
  96         }
  97
  98         if (ret != -1)
  99                 sensor_info[s].selected_trigger = trigger_val;
 100         else
 101                 ALOGE("Setting S%d (%s) trigger to %s FAILED.\n", s,
 102                         sensor_info[s].friendly_name, trigger_val);
 103         return ret;
 104 }
 105
 106
 107 void build_sensor_report_maps(int dev_num)
 108 {
 109         /*
 110          * Read sysfs files from a iio device's scan_element directory, and
 111          * build a couple of tables from that data. These tables will tell, for
 112          * each sensor, where to gather relevant data in a device report, i.e.
 113          * the structure that we read from the /dev/iio:deviceX file in order to
 114          * sensor report, itself being the data that we return to Android when a
 115          * sensor poll completes. The mapping should be straightforward in the
 116          * case where we have a single sensor active per iio device but, this is
 117          * not the general case. In general several sensors can be handled
 118          * through a single iio device, and the _en, _index and _type syfs
 119          * entries all concur to paint a picture of what the structure of the
 120          * device report is.
 121          */
 122
 123         int s;
 124         int c;
 125         int n;
 126         int i;
 127         int ch_index;
 128         char* ch_spec;
 129         char spec_buf[MAX_TYPE_SPEC_LEN];
 130         struct datum_info_t* ch_info;
 131         int size;
 132         char sysfs_path[PATH_MAX];
 133         int known_channels;
 134         int offset;
 135         int channel_size_from_index[MAX_SENSORS * MAX_CHANNELS] = { 0 };
 136         int sensor_handle_from_index[MAX_SENSORS * MAX_CHANNELS] = { 0 };
 137         int channel_number_from_index[MAX_SENSORS * MAX_CHANNELS] = { 0 };
 138
 139         known_channels = 0;
 140
 141         /* For each sensor that is linked to this device */
 142         for (s=0; s<sensor_count; s++) {
 143                 if (sensor_info[s].dev_num != dev_num)
 144                         continue;
 145
 146                 i = sensor_info[s].catalog_index;
 147
 148                 /* Read channel details through sysfs attributes */
 149                 for (c=0; c<sensor_info[s].num_channels; c++) {
 150
 151                         /* Read _type file */
 152                         sprintf(sysfs_path, CHANNEL_PATH "%s",
 153                                 sensor_info[s].dev_num,
 154                                 sensor_catalog[i].channel[c].type_path);
 155
 156                         n = sysfs_read_str(sysfs_path, spec_buf,
 157                                                 sizeof(spec_buf));
 158
 159                         if (n == -1) {
 160                                         ALOGW(  "Failed to read type: %s\n",
 161                                         sysfs_path);
 162                                         continue;
 163                                 }
 164
 165                         ch_spec = sensor_info[s].channel[c].type_spec;
 166
 167                         memcpy(ch_spec, spec_buf, sizeof(spec_buf));
 168
 169                         ch_info = &sensor_info[s].channel[c].type_info;
 170
 171                         size = decode_type_spec(ch_spec, ch_info);
 172
 173                         /* Read _index file */
 174                         sprintf(sysfs_path, CHANNEL_PATH "%s",
 175                                 sensor_info[s].dev_num,
 176                                 sensor_catalog[i].channel[c].index_path);
 177
 178                         n = sysfs_read_int(sysfs_path, &ch_index);
 179
 180                         if (n == -1) {
 181                                         ALOGW(  "Failed to read index: %s\n",
 182                                                 sysfs_path);
 183                                         continue;
 184                                 }
 185
 186                         if (ch_index >= MAX_SENSORS) {
 187                                 ALOGE("Index out of bounds!: %s\n", sysfs_path);
 188                                 continue;
 189                         }
 190
 191                         /* Record what this index is about */
 192
 193                         sensor_handle_from_index [ch_index] = s;
 194                         channel_number_from_index[ch_index] = c;
 195                         channel_size_from_index  [ch_index] = size;
 196
 197                         known_channels++;
 198                 }
 199
 200                 /* Stop sampling - if we are recovering from hal restart */
 201                 enable_buffer(dev_num, 0);
 202                 setup_trigger(s, "\n");
 203
 204                 /* Turn on channels we're aware of */
 205                 for (c=0;c<sensor_info[s].num_channels; c++) {
 206                         sprintf(sysfs_path, CHANNEL_PATH "%s",
 207                                 sensor_info[s].dev_num,
 208                                 sensor_catalog[i].channel[c].en_path);
 209                         sysfs_write_int(sysfs_path, 1);
 210                 }
 211         }
 212
 213         ALOGI("Found %d channels on iio device %d\n", known_channels, dev_num);
 214
 215         /*
 216          * Now that we know which channels are defined, their sizes and their
 217          * ordering, update channels offsets within device report. Note: there
 218          * is a possibility that several sensors share the same index, with
 219          * their data fields being isolated by masking and shifting as specified
 220          * through the real bits and shift values in type attributes. This case
 221          * is not currently supported. Also, the code below assumes no hole in
 222          * the sequence of indices, so it is dependent on discovery of all
 223          * sensors.
 224          */
 225          offset = 0;
 226          for (i=0; i<MAX_SENSORS * MAX_CHANNELS; i++) {
 227                 s =     sensor_handle_from_index[i];
 228                 c =     channel_number_from_index[i];
 229                 size =  channel_size_from_index[i];
 230
 231                 if (!size)
 232                         continue;
 233
 234                 ALOGI("S%d C%d : offset %d, size %d, type %s\n",
 235                       s, c, offset, size, sensor_info[s].channel[c].type_spec);
 236
 237                 sensor_info[s].channel[c].offset        = offset;
 238                 sensor_info[s].channel[c].size          = size;
 239
 240                 offset += size;
 241          }
 242 }
 243
 244
 245 int adjust_counters (int s, int enabled)
 246 {
 247         /*
 248          * Adjust counters based on sensor enable action. Return values are:
 249          * -1 if there's an inconsistency: abort action in this case
 250          *  0 if the operation was completed and we're all set
 251          *  1 if we toggled the state of the sensor and there's work left
 252          */
 253
 254         int dev_num = sensor_info[s].dev_num;
 255
 256         /* Refcount per sensor, in terms of enable count */
 257         if (enabled) {
 258                 ALOGI("Enabling sensor %d (iio device %d: %s)\n",
 259                         s, dev_num, sensor_info[s].friendly_name);
 260
 261                 sensor_info[s].enable_count++;
 262
 263                 if (sensor_info[s].enable_count > 1)
 264                         return 0; /* The sensor was, and remains, in use */
 265
 266                 switch (sensor_info[s].type) {
 267                         case SENSOR_TYPE_MAGNETIC_FIELD:
 268                                 compass_read_data(&sensor_info[s]);
 269                                 break;
 270
 271                         case SENSOR_TYPE_GYROSCOPE:
 272                         case SENSOR_TYPE_GYROSCOPE_UNCALIBRATED:
 273                                 gyro_cal_init(&sensor_info[s]);
 274                                 break;
 275                 }
 276         } else {
 277                 if (sensor_info[s].enable_count == 0)
 278                         return -1; /* Spurious disable call */
 279
 280                 ALOGI("Disabling sensor %d (iio device %d: %s)\n", s, dev_num,
 281                       sensor_info[s].friendly_name);
 282
 283                 sensor_info[s].enable_count--;
 284
 285                 if (sensor_info[s].enable_count > 0)
 286                         return 0; /* The sensor was, and remains, in use */
 287
 288                 /* Sensor disabled, lower report available flag */
 289                 sensor_info[s].report_pending = 0;
 290
 291                 if (sensor_info[s].type == SENSOR_TYPE_MAGNETIC_FIELD)
 292                         compass_store_data(&sensor_info[s]);
 293
 294                 if(sensor_info[s].type == SENSOR_TYPE_GYROSCOPE ||
 295                         sensor_info[s].type == SENSOR_TYPE_GYROSCOPE_UNCALIBRATED)
 296                         gyro_store_data(&sensor_info[s]);
 297         }
 298
 299
 300         /* If uncalibrated type and pair is already active don't adjust counters */
 301         if (sensor_info[s].type == SENSOR_TYPE_GYROSCOPE_UNCALIBRATED &&
 302                 sensor_info[sensor_info[s].pair_idx].enable_count != 0)
 303                         return 0;
 304
 305         /* We changed the state of a sensor - adjust per iio device counters */
 306
 307         /* If this is a regular event-driven sensor */
 308         if (sensor_info[s].num_channels) {
 309
 310                         if (enabled)
 311                                 trig_sensors_per_dev[dev_num]++;
 312                         else
 313                                 trig_sensors_per_dev[dev_num]--;
 314
 315                         return 1;
 316                 }
 317
 318         if (enabled) {
 319                 active_poll_sensors++;
 320                 poll_sensors_per_dev[dev_num]++;
 321                 return 1;
 322         }
 323
 324         active_poll_sensors--;
 325         poll_sensors_per_dev[dev_num]--;
 326         return 1;
 327 }
 328
 329
 330 static int get_field_count (int s)
 331 {
 332         switch (sensor_info[s].type) {
 333                 case SENSOR_TYPE_ACCELEROMETER:         /* m/s^2        */
 334                 case SENSOR_TYPE_MAGNETIC_FIELD:        /* micro-tesla  */
 335                 case SENSOR_TYPE_ORIENTATION:           /* degrees      */
 336                 case SENSOR_TYPE_GYROSCOPE_UNCALIBRATED:
 337                 case SENSOR_TYPE_GYROSCOPE:             /* radians/s    */
 338                         return 3;
 339
 340                 case SENSOR_TYPE_LIGHT:                 /* SI lux units */
 341                 case SENSOR_TYPE_AMBIENT_TEMPERATURE:   /* °C          */
 342                 case SENSOR_TYPE_TEMPERATURE:           /* °C          */
 343                 case SENSOR_TYPE_PROXIMITY:             /* centimeters  */
 344                 case SENSOR_TYPE_PRESSURE:              /* hecto-pascal */
 345                 case SENSOR_TYPE_RELATIVE_HUMIDITY:     /* percent */
 346                         return 1;
 347
 348                 case SENSOR_TYPE_ROTATION_VECTOR:
 349                         return  4;
 350
 351                 default:
 352                         ALOGE("Unknown sensor type!\n");
 353                         return 0;                       /* Drop sample */
 354         }
 355 }
 356
 357
 358 static void* acquisition_routine (void* param)
 359 {
 360         /*
 361          * Data acquisition routine run in a dedicated thread, covering a single
 362          * sensor. This loop will periodically retrieve sampling data through
 363          * sysfs, then package it as a sample and transfer it to our master poll
 364          * loop through a report fd. Checks for a cancellation signal quite
 365          * frequently, as the thread may be disposed of at any time. Note that
 366          * Bionic does not provide pthread_cancel / pthread_testcancel...
 367          */
 368
 369         int s = (int) (size_t) param;
 370         int num_fields, sample_size;
 371         struct sensors_event_t data = {0};
 372         int c;
 373         int ret;
 374         struct timespec target_time;
 375         int64_t timestamp, period;
 376
 377         if (s < 0 || s >= sensor_count) {
 378                 ALOGE("Invalid sensor handle!\n");
 379                 return NULL;
 380         }
 381
 382         ALOGI("Entering data acquisition thread S%d (%s): rate(%f), ts(%lld)\n", s,
 383                 sensor_info[s].friendly_name, sensor_info[s].sampling_rate, sensor_info[s].report_ts);
 384
 385         if (sensor_info[s].sampling_rate <= 0) {
 386                 ALOGE("Non-positive rate in acquisition routine for sensor %d: %f\n",
 387                         s, sensor_info[s].sampling_rate);
 388                 return NULL;
 389         }
 390
 391         num_fields = get_field_count(s);
 392         sample_size = num_fields * sizeof(float);
 393
 394         /*
 395          * Each condition variable is associated to a mutex that has to be
 396          * locked by the thread that's waiting on it. We use these condition
 397          * variables to get the acquisition threads out of sleep quickly after
 398          * the sampling rate is adjusted, or the sensor is disabled.
 399          */
 400         pthread_mutex_lock(&thread_release_mutex[s]);
 401
 402         /* Pinpoint the moment we start sampling */
 403         timestamp = get_timestamp_monotonic();
 404
 405         /* Check and honor termination requests */
 406         while (sensor_info[s].thread_data_fd[1] != -1) {
 407
 408                 /* Read values through sysfs */
 409                 for (c=0; c<num_fields; c++) {
 410                         data.data[c] = acquire_immediate_value(s, c);
 411                         /* Check and honor termination requests */
 412                         if (sensor_info[s].thread_data_fd[1] == -1)
 413                                 goto exit;
 414                 }
 415
 416                 /* If the sample looks good */
 417                 if (sensor_info[s].ops.finalize(s, &data)) {
 418
 419                         /* Pipe it for transmission to poll loop */
 420                         ret = write(    sensor_info[s].thread_data_fd[1],
 421                                         data.data, sample_size);
 422                         if (ret != sample_size)
 423                                 ALOGE("S%d acquisition thread: tried to write %d, ret: %d\n",
 424                                         s, sample_size, ret);
 425                 }
 426
 427                 /* Check and honor termination requests */
 428                 if (sensor_info[s].thread_data_fd[1] == -1)
 429                         goto exit;
 430
 431                 /* Recalculate period asumming sensor_info[s].sampling_rate
 432                  * can be changed dynamically during the thread run */
 433                 if (sensor_info[s].sampling_rate <= 0) {
 434                         ALOGE("Non-positive rate in acquisition routine for sensor %d: %f\n",
 435                                 s, sensor_info[s].sampling_rate);
 436                         goto exit;
 437                 }
 438
 439                 period = (int64_t) (1000000000LL / sensor_info[s].sampling_rate);
 440                 timestamp += period;
 441                 set_timestamp(&target_time, timestamp);
 442
 443                 /*
 444                  * Wait until the sampling time elapses, or a rate change is
 445                  * signaled, or a thread exit is requested.
 446                  */
 447                 ret = pthread_cond_timedwait(   &thread_release_cond[s],
 448                                                 &thread_release_mutex[s],
 449                                                 &target_time);
 450         }
 451
 452 exit:
 453         ALOGV("Acquisition thread for S%d exiting\n", s);
 454         pthread_mutex_unlock(&thread_release_mutex[s]);
 455         pthread_exit(0);
 456         return NULL;
 457 }
 458
 459
 460 static void start_acquisition_thread (int s)
 461 {
 462         int incoming_data_fd;
 463         int ret;
 464
 465         struct epoll_event ev = {0};
 466
 467         ALOGV("Initializing acquisition context for sensor %d\n", s);
 468
 469         /* Create condition variable and mutex for quick thread release */
 470         ret = pthread_condattr_init(&thread_cond_attr[s]);
 471         ret = pthread_condattr_setclock(&thread_cond_attr[s], CLOCK_MONOTONIC);
 472         ret = pthread_cond_init(&thread_release_cond[s], &thread_cond_attr[s]);
 473         ret = pthread_mutex_init(&thread_release_mutex[s], NULL);
 474
 475         /* Create a pipe for inter thread communication */
 476         ret = pipe(sensor_info[s].thread_data_fd);
 477
 478         incoming_data_fd = sensor_info[s].thread_data_fd[0];
 479
 480         ev.events = EPOLLIN;
 481         ev.data.u32 = THREAD_REPORT_TAG_BASE + s;
 482
 483         /* Add incoming side of pipe to our poll set, with a suitable tag */
 484         ret = epoll_ctl(poll_fd, EPOLL_CTL_ADD, incoming_data_fd , &ev);
 485
 486         /* Create and start worker thread */
 487         ret = pthread_create(   &sensor_info[s].acquisition_thread,
 488                                 NULL,
 489                                 acquisition_routine,
 490                                 (void*) (size_t) s);
 491 }
 492
 493
 494 static void stop_acquisition_thread (int s)
 495 {
 496         int incoming_data_fd = sensor_info[s].thread_data_fd[0];
 497         int outgoing_data_fd = sensor_info[s].thread_data_fd[1];
 498
 499         ALOGV("Tearing down acquisition context for sensor %d\n", s);
 500
 501         /* Delete the incoming side of the pipe from our poll set */
 502         epoll_ctl(poll_fd, EPOLL_CTL_DEL, incoming_data_fd, NULL);
 503
 504         /* Mark the pipe ends as invalid ; that's a cheap exit flag */
 505         sensor_info[s].thread_data_fd[0] = -1;
 506         sensor_info[s].thread_data_fd[1] = -1;
 507
 508         /* Close both sides of our pipe */
 509         close(incoming_data_fd);
 510         close(outgoing_data_fd);
 511
 512         /* Stop acquisition thread and clean up thread handle */
 513         pthread_cond_signal(&thread_release_cond[s]);
 514         pthread_join(sensor_info[s].acquisition_thread, NULL);
 515
 516         /* Clean up our sensor descriptor */
 517         sensor_info[s].acquisition_thread = -1;
 518
 519         /* Delete condition variable and mutex */
 520         pthread_cond_destroy(&thread_release_cond[s]);
 521         pthread_mutex_destroy(&thread_release_mutex[s]);
 522 }
 523
 524
 525 int sensor_activate(int s, int enabled)
 526 {
 527         char device_name[PATH_MAX];
 528         struct epoll_event ev = {0};
 529         int dev_fd;
 530         int ret;
 531         int dev_num = sensor_info[s].dev_num;
 532         int is_poll_sensor = !sensor_info[s].num_channels;
 533
 534         /* Prepare the report timestamp field for the first event, see set_report_ts method */
 535         sensor_info[s].report_ts = 0;
 536         ts_delta = load_timestamp_sys_clock() - get_timestamp_monotonic();
 537
 538
 539         /* If we want to activate gyro calibrated and gyro uncalibrated is activated
 540          * Deactivate gyro uncalibrated - Uncalibrated releases handler
 541          * Activate gyro calibrated     - Calibrated has handler
 542          * Reactivate gyro uncalibrated - Uncalibrated gets data from calibrated */
 543
 544         /* If we want to deactivate gyro calibrated and gyro uncalibrated is active
 545          * Deactivate gyro uncalibrated - Uncalibrated no longer gets data from handler
 546          * Deactivate gyro calibrated   - Calibrated releases handler
 547          * Reactivate gyro uncalibrated - Uncalibrated has handler */
 548
 549         if (sensor_info[s].type == SENSOR_TYPE_GYROSCOPE &&
 550                 sensor_info[s].pair_idx && sensor_info[sensor_info[s].pair_idx].enable_count != 0) {
 551
 552                                 sensor_activate(sensor_info[s].pair_idx, 0);
 553                                 ret = sensor_activate(s, enabled);
 554                                 sensor_activate(sensor_info[s].pair_idx, 1);
 555                                 return ret;
 556         }
 557
 558         ret = adjust_counters(s, enabled);
 559
 560         /* If the operation was neutral in terms of state, we're done */
 561         if (ret <= 0)
 562                 return ret;
 563
 564         sensor_info[s].event_count = 0;
 565         sensor_info[s].meta_data_pending = 0;
 566
 567         if (!is_poll_sensor) {
 568
 569                 /* Stop sampling */
 570                 enable_buffer(dev_num, 0);
 571                 setup_trigger(s, "\n");
 572
 573                 /* If there's at least one sensor enabled on this iio device */
 574                 if (trig_sensors_per_dev[dev_num]) {
 575
 576                         /* Start sampling */
 577                         setup_trigger(s, sensor_info[s].init_trigger_name);
 578                         enable_buffer(dev_num, 1);
 579                 }
 580         }
 581
 582         /*
 583          * Make sure we have a fd on the character device ; conversely, close
 584          * the fd if no one is using associated sensors anymore. The assumption
 585          * here is that the underlying driver will power on the relevant
 586          * hardware block while someone holds a fd on the device.
 587          */
 588         dev_fd = device_fd[dev_num];
 589
 590         if (!enabled) {
 591                 if (is_poll_sensor)
 592                         stop_acquisition_thread(s);
 593
 594                 if (dev_fd != -1 && !poll_sensors_per_dev[dev_num] &&
 595                         !trig_sensors_per_dev[dev_num]) {
 596                                 /*
 597                                  * Stop watching this fd. This should be a no-op
 598                                  * in case this fd was not in the poll set.
 599                                  */
 600                                 epoll_ctl(poll_fd, EPOLL_CTL_DEL, dev_fd, NULL);
 601
 602                                 close(dev_fd);
 603                                 device_fd[dev_num] = -1;
 604                         }
 605
 606                 /* If we recorded a trail of samples for filtering, delete it */
 607                 if (sensor_info[s].history) {
 608                         free(sensor_info[s].history);
 609                         sensor_info[s].history = NULL;
 610                         sensor_info[s].history_size = 0;
 611                         if (sensor_info[s].history_sum) {
 612                                 free(sensor_info[s].history_sum);
 613                                 sensor_info[s].history_sum = NULL;
 614                         }
 615                 }
 616
 617                 return 0;
 618         }
 619
 620         if (dev_fd == -1) {
 621                 /* First enabled sensor on this iio device */
 622                 sprintf(device_name, DEV_FILE_PATH, dev_num);
 623                 dev_fd = open(device_name, O_RDONLY | O_NONBLOCK);
 624
 625                 device_fd[dev_num] = dev_fd;
 626
 627                 if (dev_fd == -1) {
 628                         ALOGE("Could not open fd on %s (%s)\n",
 629                               device_name, strerror(errno));
 630                         adjust_counters(s, 0);
 631                         return -1;
 632                 }
 633
 634                 ALOGV("Opened %s: fd=%d\n", device_name, dev_fd);
 635
 636                 if (!is_poll_sensor) {
 637
 638                         /* Add this iio device fd to the set of watched fds */
 639                         ev.events = EPOLLIN;
 640                         ev.data.u32 = dev_num;
 641
 642                         ret = epoll_ctl(poll_fd, EPOLL_CTL_ADD, dev_fd, &ev);
 643
 644                         if (ret == -1) {
 645                                 ALOGE(  "Failed adding %d to poll set (%s)\n",
 646                                         dev_fd, strerror(errno));
 647                                 return -1;
 648                         }
 649
 650                         /* Note: poll-mode fds are not readable */
 651                 }
 652         }
 653
 654         /* Ensure that on-change sensors send at least one event after enable */
 655         sensor_info[s].prev_val = -1;
 656
 657         if (is_poll_sensor)
 658                 start_acquisition_thread(s);
 659
 660         return 0;
 661 }
 662
 663
 664 static int is_fast_accelerometer (int s)
 665 {
 666         /*
 667          * Some games don't react well to accelerometers using any-motion
 668          * triggers. Even very low thresholds seem to trip them, and they tend
 669          * to request fairly high event rates. Favor continuous triggers if the
 670          * sensor is an accelerometer and uses a sampling rate of at least 25.
 671          */
 672
 673         if (sensor_info[s].type != SENSOR_TYPE_ACCELEROMETER)
 674                 return 0;
 675
 676         if (sensor_info[s].sampling_rate < 25)
 677                 return 0;
 678
 679         return 1;
 680 }
 681
 682
 683 static void enable_motion_trigger (int dev_num)
 684 {
 685         /*
 686          * In the ideal case, we enumerate two triggers per iio device ; the
 687          * default (periodically firing) trigger, and another one (the motion
 688          * trigger) that only fires up when motion is detected. This second one
 689          * allows for lesser energy consumption, but requires periodic sample
 690          * duplication at the HAL level for sensors that Android defines as
 691          * continuous. This "duplicate last sample" logic can only be engaged
 692          * once we got a first sample for the driver, so we start with the
 693          * default trigger when an iio device is first opened, then adjust the
 694          * trigger when we got events for all active sensors. Unfortunately in
 695          * the general case several sensors can be associated to a given iio
 696          * device, they can independently be controlled, and we have to adjust
 697          * the trigger in use at the iio device level depending on whether or
 698          * not appropriate conditions are met at the sensor level.
 699          */
 700
 701         int s;
 702         int i;
 703         int active_sensors = trig_sensors_per_dev[dev_num];
 704         int candidate[MAX_SENSORS];
 705         int candidate_count = 0;
 706
 707         if  (!active_sensors)
 708                 return;
 709
 710         /* Check that all active sensors are ready to switch */
 711
 712         for (s=0; s<MAX_SENSORS; s++)
 713                 if (sensor_info[s].dev_num == dev_num &&
 714                     sensor_info[s].enable_count &&
 715                     sensor_info[s].num_channels &&
 716                     (!sensor_info[s].motion_trigger_name[0] ||
 717                      !sensor_info[s].report_initialized ||
 718                      is_fast_accelerometer(s) ||
 719                      (sensor_info[s].quirks & QUIRK_FORCE_CONTINUOUS))
 720                     )
 721                         return; /* Nope */
 722
 723         /* Record which particular sensors need to switch */
 724
 725         for (s=0; s<MAX_SENSORS; s++)
 726                 if (sensor_info[s].dev_num == dev_num &&
 727                     sensor_info[s].enable_count &&
 728                     sensor_info[s].num_channels &&
 729                     sensor_info[s].selected_trigger !=
 730                         sensor_info[s].motion_trigger_name)
 731                                 candidate[candidate_count++] = s;
 732
 733         if (!candidate_count)
 734                 return;
 735
 736         /* Now engage the motion trigger for sensors which aren't using it */
 737
 738         enable_buffer(dev_num, 0);
 739
 740         for (i=0; i<candidate_count; i++) {
 741                 s = candidate[i];
 742                 setup_trigger(s, sensor_info[s].motion_trigger_name);
 743         }
 744
 745         enable_buffer(dev_num, 1);
 746 }
 747
 748 /* CTS acceptable thresholds:
 749  *      EventGapVerification.java: (th <= 1.8)
 750  *      FrequencyVerification.java: (0.9)*(expected freq) => (th <= 1.1111)
 751  */
 752 #define THRESHOLD 1.10
 753 void set_report_ts(int s, int64_t ts)
 754 {
 755         int64_t maxTs, period;
 756         int catalog_index = sensor_info[s].catalog_index;
 757         int is_accel      = (sensor_catalog[catalog_index].type == SENSOR_TYPE_ACCELEROMETER);
 758
 759         /*
 760         *  A bit of a hack to please a bunch of cts tests. They
 761         *  expect the timestamp to be exacly according to the set-up
 762         *  frequency but if we're simply getting the timestamp at hal level
 763         *  this may not be the case. Perhaps we'll get rid of this when
 764         *  we'll be reading the timestamp from the iio channel for all sensors
 765         */
 766         if (sensor_info[s].report_ts && sensor_info[s].sampling_rate &&
 767                 REPORTING_MODE(sensor_desc[s].flags) == SENSOR_FLAG_CONTINUOUS_MODE)
 768         {
 769                 period = (int64_t) (1000000000LL / sensor_info[s].sampling_rate);
 770                 maxTs = sensor_info[s].report_ts + (is_accel ? 1 : THRESHOLD) * period;
 771                 sensor_info[s].report_ts = (ts < maxTs ? ts : maxTs);
 772         } else {
 773                 sensor_info[s].report_ts = ts;
 774         }
 775 }
 776
 777 static int integrate_device_report (int dev_num)
 778 {
 779         int len;
 780         int s,c;
 781         unsigned char buf[MAX_SENSOR_REPORT_SIZE] = { 0 };
 782         int sr_offset;
 783         unsigned char *target;
 784         unsigned char *source;
 785         int size;
 786
 787         /* There's an incoming report on the specified iio device char dev fd */
 788
 789         if (dev_num < 0 || dev_num >= MAX_DEVICES) {
 790                 ALOGE("Event reported on unexpected iio device %d\n", dev_num);
 791                 return -1;
 792         }
 793
 794         if (device_fd[dev_num] == -1) {
 795                 ALOGE("Ignoring stale report on iio device %d\n", dev_num);
 796                 return -1;
 797         }
 798
 799
 800
 801         len = read(device_fd[dev_num], buf, MAX_SENSOR_REPORT_SIZE);
 802
 803         if (len == -1) {
 804                 ALOGE("Could not read report from iio device %d (%s)\n",
 805                       dev_num, strerror(errno));
 806                 return -1;
 807         }
 808
 809         ALOGV("Read %d bytes from iio device %d\n", len, dev_num);
 810
 811         /* Map device report to sensor reports */
 812
 813         for (s=0; s<MAX_SENSORS; s++)
 814                 if (sensor_info[s].dev_num == dev_num &&
 815                     sensor_info[s].enable_count) {
 816
 817                         sr_offset = 0;
 818
 819                         /* Copy data from device to sensor report buffer */
 820                         for (c=0; c<sensor_info[s].num_channels; c++) {
 821
 822                                 target = sensor_info[s].report_buffer +
 823                                         sr_offset;
 824
 825                                 source = buf + sensor_info[s].channel[c].offset;
 826
 827                                 size = sensor_info[s].channel[c].size;
 828
 829                                 memcpy(target, source, size);
 830
 831                                 sr_offset += size;
 832                         }
 833
 834                         ALOGV("Sensor %d report available (%d bytes)\n", s,
 835                               sr_offset);
 836
 837                         set_report_ts(s, get_timestamp());
 838                         sensor_info[s].report_pending = DATA_TRIGGER;
 839                         sensor_info[s].report_initialized = 1;
 840                 }
 841
 842         /* Tentatively switch to an any-motion trigger if conditions are met */
 843         enable_motion_trigger(dev_num);
 844
 845         return 0;
 846 }
 847
 848
 849 static int propagate_sensor_report (int s, struct sensors_event_t  *data)
 850 {
 851         /* There's a sensor report pending for this sensor ; transmit it */
 852
 853         int num_fields    = get_field_count(s);
 854         int c;
 855         unsigned char* current_sample;
 856
 857         /* If there's nothing to return... we're done */
 858         if (!num_fields)
 859                 return 0;
 860
 861
 862         /* Only return uncalibrated event if also gyro active */
 863         if (sensor_info[s].type == SENSOR_TYPE_GYROSCOPE_UNCALIBRATED &&
 864                 sensor_info[sensor_info[s].pair_idx].enable_count != 0)
 865                         return 0;
 866
 867         memset(data, 0, sizeof(sensors_event_t));
 868
 869         data->version   = sizeof(sensors_event_t);
 870         data->sensor    = s;
 871         data->type      = sensor_info[s].type;
 872         data->timestamp = sensor_info[s].report_ts;
 873
 874         ALOGV("Sample on sensor %d (type %d):\n", s, sensor_info[s].type);
 875
 876         current_sample = sensor_info[s].report_buffer;
 877
 878         /* If this is a poll sensor */
 879         if (!sensor_info[s].num_channels) {
 880                 /* Use the data provided by the acquisition thread */
 881                 ALOGV("Reporting data from worker thread for S%d\n", s);
 882                 memcpy(data->data, current_sample, num_fields * sizeof(float));
 883                 return 1;
 884         }
 885
 886         /* Convert the data into the expected Android-level format */
 887         for (c=0; c<num_fields; c++) {
 888
 889                 data->data[c] = sensor_info[s].ops.transform
 890                                                         (s, c, current_sample);
 891
 892                 ALOGV("\tfield %d: %f\n", c, data->data[c]);
 893                 current_sample += sensor_info[s].channel[c].size;
 894         }
 895
 896         /*
 897          * The finalize routine, in addition to its late sample processing duty,
 898          * has the final say on whether or not the sample gets sent to Android.
 899          */
 900         return sensor_info[s].ops.finalize(s, data);
 901 }
 902
 903
 904 static void synthetize_duplicate_samples (void)
 905 {
 906         /*
 907          * Some sensor types (ex: gyroscope) are defined as continuously firing
 908          * by Android, despite the fact that we can be dealing with iio drivers
 909          * that only report events for new samples. For these we generate
 910          * reports periodically, duplicating the last data we got from the
 911          * driver. This is not necessary for polling sensors.
 912          */
 913
 914         int s;
 915         int64_t current_ts;
 916         int64_t target_ts;
 917         int64_t period;
 918
 919         for (s=0; s<sensor_count; s++) {
 920
 921                 /* Ignore disabled sensors */
 922                 if (!sensor_info[s].enable_count)
 923                         continue;
 924
 925                 /* If the sensor is continuously firing, leave it alone */
 926                 if (sensor_info[s].selected_trigger !=
 927                     sensor_info[s].motion_trigger_name)
 928                         continue;
 929
 930                 /* If we haven't seen a sample, there's nothing to duplicate */
 931                 if (!sensor_info[s].report_initialized)
 932                         continue;
 933
 934                 /* If a sample was recently buffered, leave it alone too */
 935                 if (sensor_info[s].report_pending)
 936                         continue;
 937
 938                 /* We also need a valid sampling rate to be configured */
 939                 if (!sensor_info[s].sampling_rate)
 940                         continue;
 941
 942                 period = (int64_t) (1000000000.0/ sensor_info[s].sampling_rate);
 943
 944                 current_ts = get_timestamp();
 945                 target_ts = sensor_info[s].report_ts + period;
 946
 947                 if (target_ts <= current_ts) {
 948                         /* Mark the sensor for event generation */
 949                         set_report_ts(s, current_ts);
 950                         sensor_info[s].report_pending = DATA_DUPLICATE;
 951                 }
 952         }
 953 }
 954
 955
 956 static void integrate_thread_report (uint32_t tag)
 957 {
 958         int s = tag - THREAD_REPORT_TAG_BASE;
 959         int len;
 960         int expected_len;
 961
 962         expected_len = get_field_count(s) * sizeof(float);
 963
 964         len = read(sensor_info[s].thread_data_fd[0],
 965                    sensor_info[s].report_buffer,
 966                    expected_len);
 967
 968         if (len == expected_len) {
 969                 set_report_ts(s, get_timestamp());
 970                 sensor_info[s].report_pending = DATA_SYSFS;
 971         }
 972 }
 973
 974
 975 static int get_poll_wait_timeout (void)
 976 {
 977         /*
 978          * Compute an appropriate timeout value, in ms, for the epoll_wait
 979          * call that's going to await for iio device reports and incoming
 980          * reports from our sensor sysfs data reader threads.
 981          */
 982
 983         int s;
 984         int64_t target_ts = INT64_MAX;
 985         int64_t ms_to_wait;
 986         int64_t period;
 987
 988         /*
 989          * Check if we're dealing with a driver that only send events when
 990          * there is motion, despite the fact that the associated Android sensor
 991          * type is continuous rather than on-change. In that case we have to
 992          * duplicate events. Check deadline for the nearest upcoming event.
 993          */
 994         for (s=0; s<sensor_count; s++)
 995                 if (sensor_info[s].enable_count &&
 996                     sensor_info[s].selected_trigger ==
 997                     sensor_info[s].motion_trigger_name &&
 998                     sensor_info[s].sampling_rate) {
 999                         period = (int64_t) (1000000000.0 /
1000                                                 sensor_info[s].sampling_rate);
1001
1002                         if (sensor_info[s].report_ts + period < target_ts)
1003                                 target_ts = sensor_info[s].report_ts + period;
1004                 }
1005
1006         /* If we don't have such a driver to deal with */
1007         if (target_ts == INT64_MAX)
1008                 return -1; /* Infinite wait */
1009
1010         ms_to_wait = (target_ts - get_timestamp()) / 1000000;
1011
1012         /* If the target timestamp is already behind us, don't wait */
1013         if (ms_to_wait < 1)
1014                 return 0;
1015
1016         return ms_to_wait;
1017 }
1018
1019
1020 int sensor_poll(struct sensors_event_t* data, int count)
1021 {
1022         int s;
1023         int i;
1024         int nfds;
1025         struct epoll_event ev[MAX_DEVICES];
1026         int returned_events;
1027         int event_count;
1028         int uncal_start;
1029
1030         /* Get one or more events from our collection of sensors */
1031
1032 return_available_sensor_reports:
1033
1034         /* Synthetize duplicate samples if needed */
1035         synthetize_duplicate_samples();
1036
1037         returned_events = 0;
1038
1039         /* Check our sensor collection for available reports */
1040         for (s=0; s<sensor_count && returned_events < count; s++) {
1041                 if (sensor_info[s].report_pending) {
1042                         event_count = 0;
1043
1044                         /* Report this event if it looks OK */
1045                         event_count = propagate_sensor_report(s, &data[returned_events]);
1046
1047                         /* Lower flag */
1048                         sensor_info[s].report_pending = 0;
1049
1050                         /* Duplicate only if both cal & uncal are active */
1051                         if (sensor_info[s].type == SENSOR_TYPE_GYROSCOPE &&
1052                                         sensor_info[s].pair_idx && sensor_info[sensor_info[s].pair_idx].enable_count != 0) {
1053                                         struct gyro_cal* gyro_data = (struct gyro_cal*) sensor_info[s].cal_data;
1054
1055                                         memcpy(&data[returned_events + event_count], &data[returned_events],
1056                                                         sizeof(struct sensors_event_t) * event_count);
1057
1058                                         uncal_start = returned_events + event_count;
1059                                         for (i = 0; i < event_count; i++) {
1060                                                 data[uncal_start + i].type = SENSOR_TYPE_GYROSCOPE_UNCALIBRATED;
1061                                                 data[uncal_start + i].sensor = sensor_info[s].pair_idx;
1062
1063                                                 data[uncal_start + i].data[0] = data[returned_events + i].data[0] + gyro_data->bias_x;
1064                                                 data[uncal_start + i].data[1] = data[returned_events + i].data[1] + gyro_data->bias_y;
1065                                                 data[uncal_start + i].data[2] = data[returned_events + i].data[2] + gyro_data->bias_z;
1066
1067                                                 data[uncal_start + i].uncalibrated_gyro.bias[0] = gyro_data->bias_x;
1068                                                 data[uncal_start + i].uncalibrated_gyro.bias[1] = gyro_data->bias_y;
1069                                                 data[uncal_start + i].uncalibrated_gyro.bias[2] = gyro_data->bias_z;
1070                                         }
1071                                         event_count <<= 1;
1072                         }
1073                         sensor_info[sensor_info[s].pair_idx].report_pending = 0;
1074                         returned_events += event_count;
1075                         /*
1076                          * If the sample was deemed invalid or unreportable,
1077                          * e.g. had the same value as the previously reported
1078                          * value for a 'on change' sensor, silently drop it.
1079                          */
1080                 }
1081                 while (sensor_info[s].meta_data_pending) {
1082                         /* See sensors.h on these */
1083                         data[returned_events].version = META_DATA_VERSION;
1084                         data[returned_events].sensor = 0;
1085                         data[returned_events].type = SENSOR_TYPE_META_DATA;
1086                         data[returned_events].reserved0 = 0;
1087                         data[returned_events].timestamp = 0;
1088                         data[returned_events].meta_data.sensor = s;
1089                         data[returned_events].meta_data.what = META_DATA_FLUSH_COMPLETE;
1090                         returned_events++;
1091                         sensor_info[s].meta_data_pending--;
1092                 }
1093         }
1094         if (returned_events)
1095                 return returned_events;
1096
1097 await_event:
1098
1099         ALOGV("Awaiting sensor data\n");
1100
1101         nfds = epoll_wait(poll_fd, ev, MAX_DEVICES, get_poll_wait_timeout());
1102
1103         if (nfds == -1) {
1104                 ALOGE("epoll_wait returned -1 (%s)\n", strerror(errno));
1105                 goto await_event;
1106         }
1107
1108         ALOGV("%d fds signalled\n", nfds);
1109
1110         /* For each of the signalled sources */
1111         for (i=0; i<nfds; i++)
1112                 if (ev[i].events == EPOLLIN)
1113                         switch (ev[i].data.u32) {
1114                                 case 0 ... MAX_DEVICES-1:
1115                                         /* Read report from iio char dev fd */
1116                                         integrate_device_report(ev[i].data.u32);
1117                                         break;
1118
1119                                 case THREAD_REPORT_TAG_BASE ...
1120                                      THREAD_REPORT_TAG_BASE + MAX_SENSORS-1:
1121                                         /* Get report from acquisition thread */
1122                                         integrate_thread_report(ev[i].data.u32);
1123                                         break;
1124
1125                                 default:
1126                                         ALOGW("Unexpected event source!\n");
1127                                         break;
1128                         }
1129
1130         goto return_available_sensor_reports;
1131 }
1132
1133
1134 static void tentative_switch_trigger (int s)
1135 {
1136         /*
1137          * Under certain situations it may be beneficial to use an alternate
1138          * trigger:
1139          *
1140          * - for applications using the accelerometer with high sampling rates,
1141          *   prefer the continuous trigger over the any-motion one, to avoid
1142          *   jumps related to motion thresholds
1143          */
1144
1145         if (is_fast_accelerometer(s) &&
1146                 !(sensor_info[s].quirks & QUIRK_TERSE_DRIVER) &&
1147                         sensor_info[s].selected_trigger ==
1148                                 sensor_info[s].motion_trigger_name)
1149                 setup_trigger(s, sensor_info[s].init_trigger_name);
1150 }
1151
1152
1153 int sensor_set_delay(int s, int64_t ns)
1154 {
1155         /* Set the rate at which a specific sensor should report events */
1156
1157         /* See Android sensors.h for indication on sensor trigger modes */
1158
1159         char sysfs_path[PATH_MAX];
1160         char avail_sysfs_path[PATH_MAX];
1161         int dev_num             =       sensor_info[s].dev_num;
1162         int i                   =       sensor_info[s].catalog_index;
1163         const char *prefix      =       sensor_catalog[i].tag;
1164         float new_sampling_rate; /* Granted sampling rate after arbitration   */
1165         float cur_sampling_rate; /* Currently used sampling rate              */
1166         int per_sensor_sampling_rate;
1167         int per_device_sampling_rate;
1168         int32_t min_delay_us = sensor_desc[s].minDelay;
1169         max_delay_t max_delay_us = sensor_desc[s].maxDelay;
1170         float min_supported_rate = max_delay_us ? (1000000.0f / max_delay_us) : 1;
1171         float max_supported_rate =
1172                 (min_delay_us && min_delay_us != -1) ? (1000000.0f / min_delay_us) : 0;
1173         char freqs_buf[100];
1174         char* cursor;
1175         int n;
1176         float sr;
1177
1178         if (ns <= 0) {
1179                 ALOGE("Rejecting non-positive delay request on sensor %d, required delay: %lld\n", s, ns);
1180                 return -EINVAL;
1181         }
1182
1183         new_sampling_rate = 1000000000LL/ns;
1184
1185         ALOGV("Entering set delay S%d (%s): old rate(%f), new rate(%f)\n",
1186                 s, sensor_info[s].friendly_name, sensor_info[s].sampling_rate,
1187                 new_sampling_rate);
1188
1189         /*
1190          * Artificially limit ourselves to 1 Hz or higher. This is mostly to
1191          * avoid setting up the stage for divisions by zero.
1192          */
1193         if (new_sampling_rate < min_supported_rate)
1194                 new_sampling_rate = min_supported_rate;
1195
1196         if (max_supported_rate &&
1197                 new_sampling_rate > max_supported_rate) {
1198                 new_sampling_rate = max_supported_rate;
1199         }
1200
1201         sensor_info[s].sampling_rate = new_sampling_rate;
1202
1203         /* If we're dealing with a poll-mode sensor */
1204         if (!sensor_info[s].num_channels) {
1205                 /* Interrupt current sleep so the new sampling gets used */
1206                 pthread_cond_signal(&thread_release_cond[s]);
1207                 return 0;
1208         }
1209
1210         sprintf(sysfs_path, SENSOR_SAMPLING_PATH, dev_num, prefix);
1211
1212         if (sysfs_read_float(sysfs_path, &cur_sampling_rate) != -1) {
1213                 per_sensor_sampling_rate = 1;
1214                 per_device_sampling_rate = 0;
1215         } else {
1216                 per_sensor_sampling_rate = 0;
1217
1218                 sprintf(sysfs_path, DEVICE_SAMPLING_PATH, dev_num);
1219
1220                 if (sysfs_read_float(sysfs_path, &cur_sampling_rate) != -1)
1221                         per_device_sampling_rate = 1;
1222                 else
1223                         per_device_sampling_rate = 0;
1224         }
1225
1226         if (!per_sensor_sampling_rate && !per_device_sampling_rate) {
1227                 ALOGE("No way to adjust sampling rate on sensor %d\n", s);
1228                 return -ENOSYS;
1229         }
1230
1231         /* Coordinate with others active sensors on the same device, if any */
1232         if (per_device_sampling_rate)
1233                 for (n=0; n<sensor_count; n++)
1234                         if (n != s && sensor_info[n].dev_num == dev_num &&
1235                             sensor_info[n].num_channels &&
1236                             sensor_info[n].enable_count &&
1237                             sensor_info[n].sampling_rate > new_sampling_rate)
1238                                 new_sampling_rate= sensor_info[n].sampling_rate;
1239
1240         /* Check if we have contraints on allowed sampling rates */
1241
1242         sprintf(avail_sysfs_path, DEVICE_AVAIL_FREQ_PATH, dev_num);
1243
1244         if (sysfs_read_str(avail_sysfs_path, freqs_buf, sizeof(freqs_buf)) > 0){
1245                 cursor = freqs_buf;
1246
1247                 /* Decode allowed sampling rates string, ex: "10 20 50 100" */
1248
1249                 /* While we're not at the end of the string */
1250                 while (*cursor && cursor[0]) {
1251
1252                         /* Decode a single value */
1253                         sr = strtod(cursor, NULL);
1254
1255                         /* If this matches the selected rate, we're happy */
1256                         if (new_sampling_rate == sr)
1257                                 break;
1258
1259                         /*
1260                          * If we reached a higher value than the desired rate,
1261                          * adjust selected rate so it matches the first higher
1262                          * available one and stop parsing - this makes the
1263                          * assumption that rates are sorted by increasing value
1264                          * in the allowed frequencies string.
1265                          */
1266                         if (sr > new_sampling_rate) {
1267                                 new_sampling_rate = sr;
1268                                 break;
1269                         }
1270
1271                         /* Skip digits */
1272                         while (cursor[0] && !isspace(cursor[0]))
1273                                 cursor++;
1274
1275                         /* Skip spaces */
1276                         while (cursor[0] && isspace(cursor[0]))
1277                                         cursor++;
1278                 }
1279         }
1280
1281         if (max_supported_rate &&
1282                 new_sampling_rate > max_supported_rate) {
1283                 new_sampling_rate = max_supported_rate;
1284         }
1285
1286         /* If the desired rate is already active we're all set */
1287         if (new_sampling_rate == cur_sampling_rate)
1288                 return 0;
1289
1290         ALOGI("Sensor %d sampling rate set to %g\n", s, new_sampling_rate);
1291
1292         if (trig_sensors_per_dev[dev_num])
1293                 enable_buffer(dev_num, 0);
1294
1295         sysfs_write_float(sysfs_path, new_sampling_rate);
1296
1297         /* Check if it makes sense to use an alternate trigger */
1298         tentative_switch_trigger(s);
1299
1300         if (trig_sensors_per_dev[dev_num])
1301                 enable_buffer(dev_num, 1);
1302
1303         return 0;
1304 }
1305
1306 int sensor_flush (int s)
1307 {
1308         /* If one shot or not enabled return -EINVAL */
1309         if (sensor_desc[s].flags & SENSOR_FLAG_ONE_SHOT_MODE ||
1310                 sensor_info[s].enable_count == 0)
1311                 return -EINVAL;
1312
1313         sensor_info[s].meta_data_pending++;
1314         return 0;
1315 }
1316
1317 int allocate_control_data (void)
1318 {
1319         int i;
1320
1321         for (i=0; i<MAX_DEVICES; i++)
1322                 device_fd[i] = -1;
1323
1324         poll_fd = epoll_create(MAX_DEVICES);
1325
1326         if (poll_fd == -1) {
1327                 ALOGE("Can't create epoll instance for iio sensors!\n");
1328                 return -1;
1329         }
1330
1331         return poll_fd;
1332 }
1333
1334
1335 void delete_control_data (void)
1336 {
1337 }