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