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 #include "filtering.h"
  21
  22 /* Currently active sensors count, per device */
  23 static int poll_sensors_per_dev[MAX_DEVICES];   /* poll-mode sensors */
  24 static int trig_sensors_per_dev[MAX_DEVICES];   /* trigger, event based */
  25
  26 static int device_fd[MAX_DEVICES];   /* fd on the /dev/iio:deviceX file */
  27 static int has_iio_ts[MAX_DEVICES];  /* ts channel available on this iio dev */
  28 static int expected_dev_report_size[MAX_DEVICES]; /* expected iio scan len */
  29 static int poll_fd; /* epoll instance covering all enabled sensors */
  30
  31 static int active_poll_sensors; /* Number of enabled poll-mode sensors */
  32
  33 static int64_t sys_to_rt_delta; /* delta between system and realtime clocks */
  34
  35 /* We use pthread condition variables to get worker threads out of sleep */
  36 static pthread_condattr_t thread_cond_attr      [MAX_SENSORS];
  37 static pthread_cond_t     thread_release_cond   [MAX_SENSORS];
  38 static pthread_mutex_t    thread_release_mutex  [MAX_SENSORS];
  39
  40 /*
  41  * We associate tags to each of our poll set entries. These tags have the
  42  * following values:
  43  * - a iio device number if the fd is a iio character device fd
  44  * - THREAD_REPORT_TAG_BASE + sensor handle if the fd is the receiving end of a
  45  *   pipe used by a sysfs data acquisition thread
  46  *  */
  47 #define THREAD_REPORT_TAG_BASE  0x00010000
  48
  49 #define ENABLE_BUFFER_RETRIES 10
  50 #define ENABLE_BUFFER_RETRY_DELAY_MS 10
  51
  52 static int enable_buffer(int dev_num, int enabled)
  53 {
  54         char sysfs_path[PATH_MAX];
  55         int ret, retries, millisec;
  56         struct timespec req = {0};
  57
  58         retries = ENABLE_BUFFER_RETRIES;
  59         millisec = ENABLE_BUFFER_RETRY_DELAY_MS;
  60         req.tv_sec = 0;
  61         req.tv_nsec = millisec * 1000000L;
  62
  63         sprintf(sysfs_path, ENABLE_PATH, dev_num);
  64
  65         while (retries--) {
  66                 /* Low level, non-multiplexed, enable/disable routine */
  67                 ret = sysfs_write_int(sysfs_path, enabled);
  68                 if (ret > 0)
  69                         break;
  70
  71                 ALOGE("Failed enabling buffer, retrying");
  72                 nanosleep(&req, (struct timespec *)NULL);
  73         }
  74
  75         if (ret < 0) {
  76                 ALOGE("Could not enable buffer\n");
  77                 return -EIO;
  78         }
  79
  80         return 0;
  81 }
  82
  83
  84 static int setup_trigger (int s, const char* trigger_val)
  85 {
  86         char sysfs_path[PATH_MAX];
  87         int ret = -1, attempts = 5;
  88
  89         sprintf(sysfs_path, TRIGGER_PATH, sensor_info[s].dev_num);
  90
  91         if (trigger_val[0] != '\n')
  92                 ALOGI("Setting S%d (%s) trigger to %s\n", s,
  93                         sensor_info[s].friendly_name, trigger_val);
  94
  95         while (ret == -1 && attempts) {
  96                 ret = sysfs_write_str(sysfs_path, trigger_val);
  97                 attempts--;
  98         }
  99
 100         if (ret != -1)
 101                 sensor_info[s].selected_trigger = trigger_val;
 102         else
 103                 ALOGE("Setting S%d (%s) trigger to %s FAILED.\n", s,
 104                         sensor_info[s].friendly_name, trigger_val);
 105         return ret;
 106 }
 107
 108
 109 static void enable_iio_timestamp (int dev_num, int known_channels)
 110 {
 111         /* Check if we have a dedicated iio timestamp channel */
 112
 113         char spec_buf[MAX_TYPE_SPEC_LEN];
 114         char sysfs_path[PATH_MAX];
 115         int n;
 116
 117         sprintf(sysfs_path, CHANNEL_PATH "%s", dev_num, "in_timestamp_type");
 118
 119         n = sysfs_read_str(sysfs_path, spec_buf, sizeof(spec_buf));
 120
 121         if (n <= 0)
 122                 return;
 123
 124         if (strcmp(spec_buf, "le:s64/64>>0"))
 125                 return;
 126
 127         /* OK, type is int64_t as expected, in little endian representation */
 128
 129         sprintf(sysfs_path, CHANNEL_PATH"%s", dev_num, "in_timestamp_index");
 130
 131         if (sysfs_read_int(sysfs_path, &n))
 132                 return;
 133
 134         /* Check that the timestamp comes after the other fields we read */
 135         if (n != known_channels)
 136                 return;
 137
 138         /* Try enabling that channel */
 139         sprintf(sysfs_path, CHANNEL_PATH "%s", dev_num, "in_timestamp_en");
 140
 141         sysfs_write_int(sysfs_path, 1);
 142
 143         if (sysfs_read_int(sysfs_path, &n))
 144                 return;
 145
 146         if (n) {
 147                 ALOGI("Detected timestamp channel on iio device %d\n", dev_num);
 148                 has_iio_ts[dev_num] = 1;
 149         }
 150 }
 151
 152
 153 void build_sensor_report_maps (int dev_num)
 154 {
 155         /*
 156          * Read sysfs files from a iio device's scan_element directory, and
 157          * build a couple of tables from that data. These tables will tell, for
 158          * each sensor, where to gather relevant data in a device report, i.e.
 159          * the structure that we read from the /dev/iio:deviceX file in order to
 160          * sensor report, itself being the data that we return to Android when a
 161          * sensor poll completes. The mapping should be straightforward in the
 162          * case where we have a single sensor active per iio device but, this is
 163          * not the general case. In general several sensors can be handled
 164          * through a single iio device, and the _en, _index and _type syfs
 165          * entries all concur to paint a picture of what the structure of the
 166          * device report is.
 167          */
 168
 169         int s;
 170         int c;
 171         int n;
 172         int i;
 173         int ch_index;
 174         char* ch_spec;
 175         char spec_buf[MAX_TYPE_SPEC_LEN];
 176         struct datum_info_t* ch_info;
 177         int size;
 178         char sysfs_path[PATH_MAX];
 179         int known_channels;
 180         int offset;
 181         int channel_size_from_index[MAX_SENSORS * MAX_CHANNELS] = { 0 };
 182         int sensor_handle_from_index[MAX_SENSORS * MAX_CHANNELS] = { 0 };
 183         int channel_number_from_index[MAX_SENSORS * MAX_CHANNELS] = { 0 };
 184
 185         known_channels = 0;
 186
 187         /* For each sensor that is linked to this device */
 188         for (s=0; s<sensor_count; s++) {
 189                 if (sensor_info[s].dev_num != dev_num)
 190                         continue;
 191
 192                 i = sensor_info[s].catalog_index;
 193
 194                 /* Read channel details through sysfs attributes */
 195                 for (c=0; c<sensor_info[s].num_channels; c++) {
 196
 197                         /* Read _type file */
 198                         sprintf(sysfs_path, CHANNEL_PATH "%s",
 199                                 sensor_info[s].dev_num,
 200                                 sensor_catalog[i].channel[c].type_path);
 201
 202                         n = sysfs_read_str(sysfs_path, spec_buf,
 203                                                 sizeof(spec_buf));
 204
 205                         if (n == -1) {
 206                                         ALOGW(  "Failed to read type: %s\n",
 207                                         sysfs_path);
 208                                         continue;
 209                                 }
 210
 211                         ch_spec = sensor_info[s].channel[c].type_spec;
 212
 213                         memcpy(ch_spec, spec_buf, sizeof(spec_buf));
 214
 215                         ch_info = &sensor_info[s].channel[c].type_info;
 216
 217                         size = decode_type_spec(ch_spec, ch_info);
 218
 219                         /* Read _index file */
 220                         sprintf(sysfs_path, CHANNEL_PATH "%s",
 221                                 sensor_info[s].dev_num,
 222                                 sensor_catalog[i].channel[c].index_path);
 223
 224                         n = sysfs_read_int(sysfs_path, &ch_index);
 225
 226                         if (n == -1) {
 227                                         ALOGW(  "Failed to read index: %s\n",
 228                                                 sysfs_path);
 229                                         continue;
 230                                 }
 231
 232                         if (ch_index >= MAX_SENSORS) {
 233                                 ALOGE("Index out of bounds!: %s\n", sysfs_path);
 234                                 continue;
 235                         }
 236
 237                         /* Record what this index is about */
 238
 239                         sensor_handle_from_index [ch_index] = s;
 240                         channel_number_from_index[ch_index] = c;
 241                         channel_size_from_index  [ch_index] = size;
 242
 243                         known_channels++;
 244                 }
 245
 246                 /* Stop sampling - if we are recovering from hal restart */
 247                 enable_buffer(dev_num, 0);
 248                 setup_trigger(s, "\n");
 249
 250                 /* Turn on channels we're aware of */
 251                 for (c=0;c<sensor_info[s].num_channels; c++) {
 252                         sprintf(sysfs_path, CHANNEL_PATH "%s",
 253                                 sensor_info[s].dev_num,
 254                                 sensor_catalog[i].channel[c].en_path);
 255                         sysfs_write_int(sysfs_path, 1);
 256                 }
 257         }
 258
 259         ALOGI("Found %d channels on iio device %d\n", known_channels, dev_num);
 260
 261         /*
 262          * Now that we know which channels are defined, their sizes and their
 263          * ordering, update channels offsets within device report. Note: there
 264          * is a possibility that several sensors share the same index, with
 265          * their data fields being isolated by masking and shifting as specified
 266          * through the real bits and shift values in type attributes. This case
 267          * is not currently supported. Also, the code below assumes no hole in
 268          * the sequence of indices, so it is dependent on discovery of all
 269          * sensors.
 270          */
 271          offset = 0;
 272          for (i=0; i<MAX_SENSORS * MAX_CHANNELS; i++) {
 273                 s =     sensor_handle_from_index[i];
 274                 c =     channel_number_from_index[i];
 275                 size =  channel_size_from_index[i];
 276
 277                 if (!size)
 278                         continue;
 279
 280                 ALOGI("S%d C%d : offset %d, size %d, type %s\n",
 281                       s, c, offset, size, sensor_info[s].channel[c].type_spec);
 282
 283                 sensor_info[s].channel[c].offset        = offset;
 284                 sensor_info[s].channel[c].size          = size;
 285
 286                 offset += size;
 287          }
 288
 289         /* Enable the timestamp channel if there is one available */
 290         enable_iio_timestamp(dev_num, known_channels);
 291
 292         /* Add padding and timestamp size if it's enabled on this iio device */
 293         if (has_iio_ts[dev_num])
 294                 offset = (offset+7)/8*8 + sizeof(int64_t);
 295
 296         expected_dev_report_size[dev_num] = offset;
 297         ALOGI("Expecting %d scan length on iio dev %d\n", offset, dev_num);
 298
 299         if (expected_dev_report_size[dev_num] > MAX_DEVICE_REPORT_SIZE) {
 300                 ALOGE("Unexpectedly large scan buffer on iio dev%d: %d bytes\n",
 301                       dev_num, expected_dev_report_size[dev_num]);
 302
 303                 expected_dev_report_size[dev_num] = MAX_DEVICE_REPORT_SIZE;
 304         }
 305 }
 306
 307
 308 int adjust_counters (int s, int enabled)
 309 {
 310         /*
 311          * Adjust counters based on sensor enable action. Return values are:
 312          * -1 if there's an inconsistency: abort action in this case
 313          *  0 if the operation was completed and we're all set
 314          *  1 if we toggled the state of the sensor and there's work left
 315          */
 316
 317         int dev_num = sensor_info[s].dev_num;
 318
 319         /* Refcount per sensor, in terms of enable count */
 320         if (enabled) {
 321                 ALOGI("Enabling sensor %d (iio device %d: %s)\n",
 322                         s, dev_num, sensor_info[s].friendly_name);
 323
 324                 if (sensor_info[s].enabled)
 325                         return 0; /* The sensor was, and remains, in use */
 326
 327                 sensor_info[s].enabled = 1;
 328
 329                 switch (sensor_info[s].type) {
 330                         case SENSOR_TYPE_MAGNETIC_FIELD:
 331                                 compass_read_data(&sensor_info[s]);
 332                                 break;
 333
 334                         case SENSOR_TYPE_GYROSCOPE:
 335                         case SENSOR_TYPE_GYROSCOPE_UNCALIBRATED:
 336                                 gyro_cal_init(&sensor_info[s]);
 337                                 break;
 338                 }
 339         } else {
 340                 if (sensor_info[s].enabled == 0)
 341                         return 0; /* Spurious disable call */
 342
 343                 ALOGI("Disabling sensor %d (iio device %d: %s)\n", s, dev_num,
 344                       sensor_info[s].friendly_name);
 345
 346                 sensor_info[s].enabled = 0;
 347
 348                 /* Sensor disabled, lower report available flag */
 349                 sensor_info[s].report_pending = 0;
 350
 351                 if (sensor_info[s].type == SENSOR_TYPE_MAGNETIC_FIELD)
 352                         compass_store_data(&sensor_info[s]);
 353
 354                 if(sensor_info[s].type == SENSOR_TYPE_GYROSCOPE ||
 355                         sensor_info[s].type == SENSOR_TYPE_GYROSCOPE_UNCALIBRATED)
 356                         gyro_store_data(&sensor_info[s]);
 357         }
 358
 359
 360         /* If uncalibrated type and pair is already active don't adjust counters */
 361         if (sensor_info[s].type == SENSOR_TYPE_GYROSCOPE_UNCALIBRATED &&
 362                 sensor_info[sensor_info[s].pair_idx].enabled != 0)
 363                         return 0;
 364
 365         /* We changed the state of a sensor - adjust per iio device counters */
 366
 367         /* If this is a regular event-driven sensor */
 368         if (sensor_info[s].num_channels) {
 369
 370                         if (enabled)
 371                                 trig_sensors_per_dev[dev_num]++;
 372                         else
 373                                 trig_sensors_per_dev[dev_num]--;
 374
 375                         return 1;
 376                 }
 377
 378         if (enabled) {
 379                 active_poll_sensors++;
 380                 poll_sensors_per_dev[dev_num]++;
 381                 return 1;
 382         }
 383
 384         active_poll_sensors--;
 385         poll_sensors_per_dev[dev_num]--;
 386         return 1;
 387 }
 388
 389
 390 static int get_field_count (int s)
 391 {
 392         switch (sensor_info[s].type) {
 393                 case SENSOR_TYPE_ACCELEROMETER:         /* m/s^2        */
 394                 case SENSOR_TYPE_MAGNETIC_FIELD:        /* micro-tesla  */
 395                 case SENSOR_TYPE_ORIENTATION:           /* degrees      */
 396                 case SENSOR_TYPE_GYROSCOPE_UNCALIBRATED:
 397                 case SENSOR_TYPE_GYROSCOPE:             /* radians/s    */
 398                         return 3;
 399
 400                 case SENSOR_TYPE_LIGHT:                 /* SI lux units */
 401                 case SENSOR_TYPE_AMBIENT_TEMPERATURE:   /* °C          */
 402                 case SENSOR_TYPE_TEMPERATURE:           /* °C          */
 403                 case SENSOR_TYPE_PROXIMITY:             /* centimeters  */
 404                 case SENSOR_TYPE_PRESSURE:              /* hecto-pascal */
 405                 case SENSOR_TYPE_RELATIVE_HUMIDITY:     /* percent */
 406                         return 1;
 407
 408                 case SENSOR_TYPE_ROTATION_VECTOR:
 409                         return  4;
 410
 411                 default:
 412                         ALOGE("Unknown sensor type!\n");
 413                         return 0;                       /* Drop sample */
 414         }
 415 }
 416
 417
 418 static void* acquisition_routine (void* param)
 419 {
 420         /*
 421          * Data acquisition routine run in a dedicated thread, covering a single
 422          * sensor. This loop will periodically retrieve sampling data through
 423          * sysfs, then package it as a sample and transfer it to our master poll
 424          * loop through a report fd. Checks for a cancellation signal quite
 425          * frequently, as the thread may be disposed of at any time. Note that
 426          * Bionic does not provide pthread_cancel / pthread_testcancel...
 427          */
 428
 429         int s = (int) (size_t) param;
 430         int num_fields, sample_size;
 431         struct sensors_event_t data = {0};
 432         int c;
 433         int ret;
 434         struct timespec target_time;
 435         int64_t timestamp, period, start, stop;
 436
 437         if (s < 0 || s >= sensor_count) {
 438                 ALOGE("Invalid sensor handle!\n");
 439                 return NULL;
 440         }
 441
 442         ALOGI("Entering data acquisition thread S%d (%s): rate(%f), ts(%lld)\n", s,
 443                 sensor_info[s].friendly_name, sensor_info[s].sampling_rate, sensor_info[s].report_ts);
 444
 445         if (sensor_info[s].sampling_rate <= 0) {
 446                 ALOGE("Non-positive rate in acquisition routine for sensor %d: %f\n",
 447                         s, sensor_info[s].sampling_rate);
 448                 return NULL;
 449         }
 450
 451         num_fields = get_field_count(s);
 452         sample_size = sizeof(int64_t) + num_fields * sizeof(float);
 453
 454         /*
 455          * Each condition variable is associated to a mutex that has to be
 456          * locked by the thread that's waiting on it. We use these condition
 457          * variables to get the acquisition threads out of sleep quickly after
 458          * the sampling rate is adjusted, or the sensor is disabled.
 459          */
 460         pthread_mutex_lock(&thread_release_mutex[s]);
 461
 462         /* Pinpoint the moment we start sampling */
 463         timestamp = get_timestamp_boot();
 464
 465         /* Check and honor termination requests */
 466         while (sensor_info[s].thread_data_fd[1] != -1) {
 467                 start = get_timestamp_boot();
 468                 /* Read values through sysfs */
 469                 for (c=0; c<num_fields; c++) {
 470                         data.data[c] = acquire_immediate_value(s, c);
 471                         /* Check and honor termination requests */
 472                         if (sensor_info[s].thread_data_fd[1] == -1)
 473                                 goto exit;
 474                 }
 475                 stop = get_timestamp_boot();
 476                 data.timestamp = start/2 + stop/2;
 477
 478                 /* If the sample looks good */
 479                 if (sensor_info[s].ops.finalize(s, &data)) {
 480
 481                         /* Pipe it for transmission to poll loop */
 482                         ret = write(    sensor_info[s].thread_data_fd[1],
 483                                         &data.timestamp, sample_size);
 484
 485                         if (ret != sample_size)
 486                                 ALOGE("S%d acquisition thread: tried to write %d, ret: %d\n",
 487                                         s, sample_size, ret);
 488                 }
 489
 490                 /* Check and honor termination requests */
 491                 if (sensor_info[s].thread_data_fd[1] == -1)
 492                         goto exit;
 493
 494                 /* Recalculate period asumming sensor_info[s].sampling_rate
 495                  * can be changed dynamically during the thread run */
 496                 if (sensor_info[s].sampling_rate <= 0) {
 497                         ALOGE("Non-positive rate in acquisition routine for sensor %d: %f\n",
 498                                 s, sensor_info[s].sampling_rate);
 499                         goto exit;
 500                 }
 501
 502                 period = (int64_t) (1000000000LL / sensor_info[s].sampling_rate);
 503                 timestamp += period;
 504                 set_timestamp(&target_time, timestamp);
 505
 506                 /*
 507                  * Wait until the sampling time elapses, or a rate change is
 508                  * signaled, or a thread exit is requested.
 509                  */
 510                 ret = pthread_cond_timedwait(   &thread_release_cond[s],
 511                                                 &thread_release_mutex[s],
 512                                                 &target_time);
 513         }
 514
 515 exit:
 516         ALOGV("Acquisition thread for S%d exiting\n", s);
 517         pthread_mutex_unlock(&thread_release_mutex[s]);
 518         pthread_exit(0);
 519         return NULL;
 520 }
 521
 522
 523 static void start_acquisition_thread (int s)
 524 {
 525         int incoming_data_fd;
 526         int ret;
 527
 528         struct epoll_event ev = {0};
 529
 530         ALOGV("Initializing acquisition context for sensor %d\n", s);
 531
 532         /* Create condition variable and mutex for quick thread release */
 533         ret = pthread_condattr_init(&thread_cond_attr[s]);
 534         ret = pthread_condattr_setclock(&thread_cond_attr[s], CLOCK_MONOTONIC);
 535         ret = pthread_cond_init(&thread_release_cond[s], &thread_cond_attr[s]);
 536         ret = pthread_mutex_init(&thread_release_mutex[s], NULL);
 537
 538         /* Create a pipe for inter thread communication */
 539         ret = pipe(sensor_info[s].thread_data_fd);
 540
 541         incoming_data_fd = sensor_info[s].thread_data_fd[0];
 542
 543         ev.events = EPOLLIN;
 544         ev.data.u32 = THREAD_REPORT_TAG_BASE + s;
 545
 546         /* Add incoming side of pipe to our poll set, with a suitable tag */
 547         ret = epoll_ctl(poll_fd, EPOLL_CTL_ADD, incoming_data_fd , &ev);
 548
 549         /* Create and start worker thread */
 550         ret = pthread_create(   &sensor_info[s].acquisition_thread,
 551                                 NULL,
 552                                 acquisition_routine,
 553                                 (void*) (size_t) s);
 554 }
 555
 556
 557 static void stop_acquisition_thread (int s)
 558 {
 559         int incoming_data_fd = sensor_info[s].thread_data_fd[0];
 560         int outgoing_data_fd = sensor_info[s].thread_data_fd[1];
 561
 562         ALOGV("Tearing down acquisition context for sensor %d\n", s);
 563
 564         /* Delete the incoming side of the pipe from our poll set */
 565         epoll_ctl(poll_fd, EPOLL_CTL_DEL, incoming_data_fd, NULL);
 566
 567         /* Mark the pipe ends as invalid ; that's a cheap exit flag */
 568         sensor_info[s].thread_data_fd[0] = -1;
 569         sensor_info[s].thread_data_fd[1] = -1;
 570
 571         /* Close both sides of our pipe */
 572         close(incoming_data_fd);
 573         close(outgoing_data_fd);
 574
 575         /* Stop acquisition thread and clean up thread handle */
 576         pthread_cond_signal(&thread_release_cond[s]);
 577         pthread_join(sensor_info[s].acquisition_thread, NULL);
 578
 579         /* Clean up our sensor descriptor */
 580         sensor_info[s].acquisition_thread = -1;
 581
 582         /* Delete condition variable and mutex */
 583         pthread_cond_destroy(&thread_release_cond[s]);
 584         pthread_mutex_destroy(&thread_release_mutex[s]);
 585 }
 586
 587
 588 int sensor_activate(int s, int enabled)
 589 {
 590         char device_name[PATH_MAX];
 591         struct epoll_event ev = {0};
 592         int dev_fd;
 593         int ret;
 594         int dev_num = sensor_info[s].dev_num;
 595         int is_poll_sensor = !sensor_info[s].num_channels;
 596
 597         /* Prepare the report timestamp field for the first event, see set_report_ts method */
 598         sensor_info[s].report_ts = 0;
 599
 600         sys_to_rt_delta = get_timestamp_realtime() - get_timestamp_boot();
 601
 602
 603         /* If we want to activate gyro calibrated and gyro uncalibrated is activated
 604          * Deactivate gyro uncalibrated - Uncalibrated releases handler
 605          * Activate gyro calibrated     - Calibrated has handler
 606          * Reactivate gyro uncalibrated - Uncalibrated gets data from calibrated */
 607
 608         /* If we want to deactivate gyro calibrated and gyro uncalibrated is active
 609          * Deactivate gyro uncalibrated - Uncalibrated no longer gets data from handler
 610          * Deactivate gyro calibrated   - Calibrated releases handler
 611          * Reactivate gyro uncalibrated - Uncalibrated has handler */
 612
 613         if (sensor_info[s].type == SENSOR_TYPE_GYROSCOPE &&
 614                 sensor_info[s].pair_idx && sensor_info[sensor_info[s].pair_idx].enabled != 0) {
 615
 616                                 sensor_activate(sensor_info[s].pair_idx, 0);
 617                                 ret = sensor_activate(s, enabled);
 618                                 sensor_activate(sensor_info[s].pair_idx, 1);
 619                                 return ret;
 620         }
 621
 622         ret = adjust_counters(s, enabled);
 623
 624         /* If the operation was neutral in terms of state, we're done */
 625         if (ret <= 0)
 626                 return ret;
 627
 628         sensor_info[s].event_count = 0;
 629         sensor_info[s].meta_data_pending = 0;
 630
 631         if (enabled && (sensor_info[s].quirks & QUIRK_NOISY))
 632                 /* Initialize filtering data if required */
 633                 setup_noise_filtering(s);
 634
 635         if (!is_poll_sensor) {
 636
 637                 /* Stop sampling */
 638                 enable_buffer(dev_num, 0);
 639                 setup_trigger(s, "\n");
 640
 641                 /* If there's at least one sensor enabled on this iio device */
 642                 if (trig_sensors_per_dev[dev_num]) {
 643
 644                         /* Start sampling */
 645                         setup_trigger(s, sensor_info[s].init_trigger_name);
 646                         enable_buffer(dev_num, 1);
 647                 }
 648         }
 649
 650         /*
 651          * Make sure we have a fd on the character device ; conversely, close
 652          * the fd if no one is using associated sensors anymore. The assumption
 653          * here is that the underlying driver will power on the relevant
 654          * hardware block while someone holds a fd on the device.
 655          */
 656         dev_fd = device_fd[dev_num];
 657
 658         if (!enabled) {
 659                 if (is_poll_sensor)
 660                         stop_acquisition_thread(s);
 661
 662                 if (dev_fd != -1 && !poll_sensors_per_dev[dev_num] &&
 663                         !trig_sensors_per_dev[dev_num]) {
 664                                 /*
 665                                  * Stop watching this fd. This should be a no-op
 666                                  * in case this fd was not in the poll set.
 667                                  */
 668                                 epoll_ctl(poll_fd, EPOLL_CTL_DEL, dev_fd, NULL);
 669
 670                                 close(dev_fd);
 671                                 device_fd[dev_num] = -1;
 672                         }
 673
 674                 /* Release any filtering data we may have accumulated */
 675                 release_noise_filtering_data(s);
 676
 677                 return 0;
 678         }
 679
 680         if (dev_fd == -1) {
 681                 /* First enabled sensor on this iio device */
 682                 sprintf(device_name, DEV_FILE_PATH, dev_num);
 683                 dev_fd = open(device_name, O_RDONLY | O_NONBLOCK);
 684
 685                 device_fd[dev_num] = dev_fd;
 686
 687                 if (dev_fd == -1) {
 688                         ALOGE("Could not open fd on %s (%s)\n",
 689                               device_name, strerror(errno));
 690                         adjust_counters(s, 0);
 691                         return -1;
 692                 }
 693
 694                 ALOGV("Opened %s: fd=%d\n", device_name, dev_fd);
 695
 696                 if (!is_poll_sensor) {
 697
 698                         /* Add this iio device fd to the set of watched fds */
 699                         ev.events = EPOLLIN;
 700                         ev.data.u32 = dev_num;
 701
 702                         ret = epoll_ctl(poll_fd, EPOLL_CTL_ADD, dev_fd, &ev);
 703
 704                         if (ret == -1) {
 705                                 ALOGE(  "Failed adding %d to poll set (%s)\n",
 706                                         dev_fd, strerror(errno));
 707                                 return -1;
 708                         }
 709
 710                         /* Note: poll-mode fds are not readable */
 711                 }
 712         }
 713
 714         /* Ensure that on-change sensors send at least one event after enable */
 715         sensor_info[s].prev_val = -1;
 716
 717         if (is_poll_sensor)
 718                 start_acquisition_thread(s);
 719
 720         return 0;
 721 }
 722
 723
 724 static int is_fast_accelerometer (int s)
 725 {
 726         /*
 727          * Some games don't react well to accelerometers using any-motion
 728          * triggers. Even very low thresholds seem to trip them, and they tend
 729          * to request fairly high event rates. Favor continuous triggers if the
 730          * sensor is an accelerometer and uses a sampling rate of at least 25.
 731          */
 732
 733         if (sensor_info[s].type != SENSOR_TYPE_ACCELEROMETER)
 734                 return 0;
 735
 736         if (sensor_info[s].sampling_rate < 25)
 737                 return 0;
 738
 739         return 1;
 740 }
 741
 742
 743 static void enable_motion_trigger (int dev_num)
 744 {
 745         /*
 746          * In the ideal case, we enumerate two triggers per iio device ; the
 747          * default (periodically firing) trigger, and another one (the motion
 748          * trigger) that only fires up when motion is detected. This second one
 749          * allows for lesser energy consumption, but requires periodic sample
 750          * duplication at the HAL level for sensors that Android defines as
 751          * continuous. This "duplicate last sample" logic can only be engaged
 752          * once we got a first sample for the driver, so we start with the
 753          * default trigger when an iio device is first opened, then adjust the
 754          * trigger when we got events for all active sensors. Unfortunately in
 755          * the general case several sensors can be associated to a given iio
 756          * device, they can independently be controlled, and we have to adjust
 757          * the trigger in use at the iio device level depending on whether or
 758          * not appropriate conditions are met at the sensor level.
 759          */
 760
 761         int s;
 762         int i;
 763         int active_sensors = trig_sensors_per_dev[dev_num];
 764         int candidate[MAX_SENSORS];
 765         int candidate_count = 0;
 766
 767         if  (!active_sensors)
 768                 return;
 769
 770         /* Check that all active sensors are ready to switch */
 771
 772         for (s=0; s<MAX_SENSORS; s++)
 773                 if (sensor_info[s].dev_num == dev_num &&
 774                     sensor_info[s].enabled &&
 775                     sensor_info[s].num_channels &&
 776                     (!sensor_info[s].motion_trigger_name[0] ||
 777                      !sensor_info[s].report_initialized ||
 778                      is_fast_accelerometer(s) ||
 779                      (sensor_info[s].quirks & QUIRK_FORCE_CONTINUOUS))
 780                     )
 781                         return; /* Nope */
 782
 783         /* Record which particular sensors need to switch */
 784
 785         for (s=0; s<MAX_SENSORS; s++)
 786                 if (sensor_info[s].dev_num == dev_num &&
 787                     sensor_info[s].enabled &&
 788                     sensor_info[s].num_channels &&
 789                     sensor_info[s].selected_trigger !=
 790                         sensor_info[s].motion_trigger_name)
 791                                 candidate[candidate_count++] = s;
 792
 793         if (!candidate_count)
 794                 return;
 795
 796         /* Now engage the motion trigger for sensors which aren't using it */
 797
 798         enable_buffer(dev_num, 0);
 799
 800         for (i=0; i<candidate_count; i++) {
 801                 s = candidate[i];
 802                 setup_trigger(s, sensor_info[s].motion_trigger_name);
 803         }
 804
 805         enable_buffer(dev_num, 1);
 806 }
 807
 808 /* CTS acceptable thresholds:
 809  *      EventGapVerification.java: (th <= 1.8)
 810  *      FrequencyVerification.java: (0.9)*(expected freq) => (th <= 1.1111)
 811  */
 812 #define THRESHOLD 1.10
 813 #define MAX_DELAY 500000000 /* 500 ms */
 814 void set_report_ts(int s, int64_t ts)
 815 {
 816         int64_t maxTs, period;
 817         int catalog_index = sensor_info[s].catalog_index;
 818         int is_accel      = (sensor_catalog[catalog_index].type == SENSOR_TYPE_ACCELEROMETER);
 819
 820         /*
 821         *  A bit of a hack to please a bunch of cts tests. They
 822         *  expect the timestamp to be exacly according to the set-up
 823         *  frequency but if we're simply getting the timestamp at hal level
 824         *  this may not be the case. Perhaps we'll get rid of this when
 825         *  we'll be reading the timestamp from the iio channel for all sensors
 826         */
 827         if (sensor_info[s].report_ts && sensor_info[s].sampling_rate &&
 828                 REPORTING_MODE(sensor_desc[s].flags) == SENSOR_FLAG_CONTINUOUS_MODE)
 829         {
 830                 period = (int64_t) (1000000000LL / sensor_info[s].sampling_rate);
 831                 maxTs = sensor_info[s].report_ts + (is_accel ? 1 : THRESHOLD) * period;
 832                 /* If we're too far behind get back on track */
 833                 if (ts - maxTs >= MAX_DELAY)
 834                         maxTs = ts;
 835                 sensor_info[s].report_ts = (ts < maxTs ? ts : maxTs);
 836         } else {
 837                 sensor_info[s].report_ts = ts;
 838         }
 839 }
 840
 841
 842 static int integrate_device_report (int dev_num)
 843 {
 844         int len;
 845         int s,c;
 846         unsigned char buf[MAX_DEVICE_REPORT_SIZE] = { 0 };
 847         int sr_offset;
 848         unsigned char *target;
 849         unsigned char *source;
 850         int size;
 851         int64_t ts = 0;
 852         int ts_offset = 0;      /* Offset of iio timestamp, if provided */
 853
 854         /* There's an incoming report on the specified iio device char dev fd */
 855
 856         if (dev_num < 0 || dev_num >= MAX_DEVICES) {
 857                 ALOGE("Event reported on unexpected iio device %d\n", dev_num);
 858                 return -1;
 859         }
 860
 861         if (device_fd[dev_num] == -1) {
 862                 ALOGE("Ignoring stale report on iio device %d\n", dev_num);
 863                 return -1;
 864         }
 865
 866         len = read(device_fd[dev_num], buf, expected_dev_report_size[dev_num]);
 867
 868         if (len == -1) {
 869                 ALOGE("Could not read report from iio device %d (%s)\n",
 870                       dev_num, strerror(errno));
 871                 return -1;
 872         }
 873
 874         ALOGV("Read %d bytes from iio device %d\n", len, dev_num);
 875
 876         /* Map device report to sensor reports */
 877
 878         for (s=0; s<MAX_SENSORS; s++)
 879                 if (sensor_info[s].dev_num == dev_num &&
 880                     sensor_info[s].enabled) {
 881
 882                         sr_offset = 0;
 883
 884                         /* Copy data from device to sensor report buffer */
 885                         for (c=0; c<sensor_info[s].num_channels; c++) {
 886
 887                                 target = sensor_info[s].report_buffer +
 888                                         sr_offset;
 889
 890                                 source = buf + sensor_info[s].channel[c].offset;
 891
 892                                 size = sensor_info[s].channel[c].size;
 893
 894                                 memcpy(target, source, size);
 895
 896                                 sr_offset += size;
 897                         }
 898
 899                         ALOGV("Sensor %d report available (%d bytes)\n", s,
 900                               sr_offset);
 901
 902                         sensor_info[s].report_pending = DATA_TRIGGER;
 903                         sensor_info[s].report_initialized = 1;
 904
 905                         ts_offset += sr_offset;
 906                 }
 907
 908         /* Tentatively switch to an any-motion trigger if conditions are met */
 909         enable_motion_trigger(dev_num);
 910
 911         /* If no iio timestamp channel was detected for this device, bail out */
 912         if (!has_iio_ts[dev_num]) {
 913                 for (s=0; s<MAX_SENSORS; s++)
 914                         if (sensor_info[s].dev_num == dev_num &&
 915                                 sensor_info[s].enabled)
 916                                         set_report_ts(s, get_timestamp_boot());
 917                 return 0;
 918         }
 919
 920         /* Align on a 64 bits boundary */
 921         ts_offset = (ts_offset + 7)/8*8;
 922
 923         /* If we read an amount of data consistent with timestamp presence */
 924         if (len == expected_dev_report_size[dev_num])
 925                 ts = *(int64_t*) (buf + ts_offset);
 926
 927         if (ts == 0) {
 928                 ALOGV("Unreliable timestamp channel on iio dev %d\n", dev_num);
 929                 for (s=0; s<MAX_SENSORS; s++)
 930                         if (sensor_info[s].dev_num == dev_num &&
 931                                 sensor_info[s].enabled)
 932                                         set_report_ts(s, get_timestamp_boot());
 933                 return 0;
 934         }
 935
 936         ALOGV("Driver timestamp on iio device %d: ts=%lld\n", dev_num, ts);
 937
 938         for (s=0; s<MAX_SENSORS; s++)
 939                 if (sensor_info[s].dev_num == dev_num && sensor_info[s].enabled)
 940                         set_report_ts(s, ts - sys_to_rt_delta);
 941
 942         return 0;
 943 }
 944
 945
 946 static int propagate_sensor_report (int s, struct sensors_event_t  *data)
 947 {
 948         /* There's a sensor report pending for this sensor ; transmit it */
 949
 950         int num_fields    = get_field_count(s);
 951         int c;
 952         unsigned char* current_sample;
 953
 954         /* If there's nothing to return... we're done */
 955         if (!num_fields)
 956                 return 0;
 957
 958
 959         /* Only return uncalibrated event if also gyro active */
 960         if (sensor_info[s].type == SENSOR_TYPE_GYROSCOPE_UNCALIBRATED &&
 961                 sensor_info[sensor_info[s].pair_idx].enabled != 0)
 962                         return 0;
 963
 964         memset(data, 0, sizeof(sensors_event_t));
 965
 966         data->version   = sizeof(sensors_event_t);
 967         data->sensor    = s;
 968         data->type      = sensor_info[s].type;
 969         data->timestamp = sensor_info[s].report_ts;
 970
 971         ALOGV("Sample on sensor %d (type %d):\n", s, sensor_info[s].type);
 972
 973         current_sample = sensor_info[s].report_buffer;
 974
 975         /* If this is a poll sensor */
 976         if (!sensor_info[s].num_channels) {
 977                 /* Use the data provided by the acquisition thread */
 978                 ALOGV("Reporting data from worker thread for S%d\n", s);
 979                 memcpy(data->data, current_sample, num_fields * sizeof(float));
 980                 return 1;
 981         }
 982
 983         /* Convert the data into the expected Android-level format */
 984         for (c=0; c<num_fields; c++) {
 985
 986                 data->data[c] = sensor_info[s].ops.transform
 987                                                         (s, c, current_sample);
 988
 989                 ALOGV("\tfield %d: %f\n", c, data->data[c]);
 990                 current_sample += sensor_info[s].channel[c].size;
 991         }
 992
 993         /*
 994          * The finalize routine, in addition to its late sample processing duty,
 995          * has the final say on whether or not the sample gets sent to Android.
 996          */
 997         return sensor_info[s].ops.finalize(s, data);
 998 }
 999
1000
1001 static void synthetize_duplicate_samples (void)
1002 {
1003         /*
1004          * Some sensor types (ex: gyroscope) are defined as continuously firing
1005          * by Android, despite the fact that we can be dealing with iio drivers
1006          * that only report events for new samples. For these we generate
1007          * reports periodically, duplicating the last data we got from the
1008          * driver. This is not necessary for polling sensors.
1009          */
1010
1011         int s;
1012         int64_t current_ts;
1013         int64_t target_ts;
1014         int64_t period;
1015
1016         for (s=0; s<sensor_count; s++) {
1017
1018                 /* Ignore disabled sensors */
1019                 if (!sensor_info[s].enabled)
1020                         continue;
1021
1022                 /* If the sensor is continuously firing, leave it alone */
1023                 if (sensor_info[s].selected_trigger !=
1024                     sensor_info[s].motion_trigger_name)
1025                         continue;
1026
1027                 /* If we haven't seen a sample, there's nothing to duplicate */
1028                 if (!sensor_info[s].report_initialized)
1029                         continue;
1030
1031                 /* If a sample was recently buffered, leave it alone too */
1032                 if (sensor_info[s].report_pending)
1033                         continue;
1034
1035                 /* We also need a valid sampling rate to be configured */
1036                 if (!sensor_info[s].sampling_rate)
1037                         continue;
1038
1039                 period = (int64_t) (1000000000.0/ sensor_info[s].sampling_rate);
1040
1041                 current_ts = get_timestamp_boot();
1042                 target_ts = sensor_info[s].report_ts + period;
1043
1044                 if (target_ts <= current_ts) {
1045                         /* Mark the sensor for event generation */
1046                         set_report_ts(s, current_ts);
1047                         sensor_info[s].report_pending = DATA_DUPLICATE;
1048                 }
1049         }
1050 }
1051
1052
1053 static void integrate_thread_report (uint32_t tag)
1054 {
1055         int s = tag - THREAD_REPORT_TAG_BASE;
1056         int len;
1057         int expected_len;
1058         int64_t timestamp;
1059         unsigned char current_sample[MAX_SENSOR_REPORT_SIZE];
1060
1061         expected_len = sizeof(int64_t) + get_field_count(s) * sizeof(float);
1062
1063         len = read(sensor_info[s].thread_data_fd[0],
1064                    current_sample,
1065                    expected_len);
1066
1067         memcpy(&timestamp, current_sample, sizeof(int64_t));
1068         memcpy(sensor_info[s].report_buffer, sizeof(int64_t) + current_sample,
1069                         expected_len - sizeof(int64_t));
1070
1071         if (len == expected_len) {
1072                 set_report_ts(s, timestamp);
1073                 sensor_info[s].report_pending = DATA_SYSFS;
1074         }
1075 }
1076
1077
1078 static int get_poll_wait_timeout (void)
1079 {
1080         /*
1081          * Compute an appropriate timeout value, in ms, for the epoll_wait
1082          * call that's going to await for iio device reports and incoming
1083          * reports from our sensor sysfs data reader threads.
1084          */
1085
1086         int s;
1087         int64_t target_ts = INT64_MAX;
1088         int64_t ms_to_wait;
1089         int64_t period;
1090
1091         /*
1092          * Check if we're dealing with a driver that only send events when
1093          * there is motion, despite the fact that the associated Android sensor
1094          * type is continuous rather than on-change. In that case we have to
1095          * duplicate events. Check deadline for the nearest upcoming event.
1096          */
1097         for (s=0; s<sensor_count; s++)
1098                 if (sensor_info[s].enabled &&
1099                     sensor_info[s].selected_trigger ==
1100                     sensor_info[s].motion_trigger_name &&
1101                     sensor_info[s].sampling_rate) {
1102                         period = (int64_t) (1000000000.0 /
1103                                                 sensor_info[s].sampling_rate);
1104
1105                         if (sensor_info[s].report_ts + period < target_ts)
1106                                 target_ts = sensor_info[s].report_ts + period;
1107                 }
1108
1109         /* If we don't have such a driver to deal with */
1110         if (target_ts == INT64_MAX)
1111                 return -1; /* Infinite wait */
1112
1113         ms_to_wait = (target_ts - get_timestamp_boot()) / 1000000;
1114
1115         /* If the target timestamp is already behind us, don't wait */
1116         if (ms_to_wait < 1)
1117                 return 0;
1118
1119         return ms_to_wait;
1120 }
1121
1122
1123 int sensor_poll(struct sensors_event_t* data, int count)
1124 {
1125         int s;
1126         int i;
1127         int nfds;
1128         struct epoll_event ev[MAX_DEVICES];
1129         int returned_events;
1130         int event_count;
1131         int uncal_start;
1132
1133         /* Get one or more events from our collection of sensors */
1134
1135 return_available_sensor_reports:
1136
1137         /* Synthetize duplicate samples if needed */
1138         synthetize_duplicate_samples();
1139
1140         returned_events = 0;
1141
1142         /* Check our sensor collection for available reports */
1143         for (s=0; s<sensor_count && returned_events < count; s++) {
1144                 if (sensor_info[s].report_pending) {
1145                         event_count = 0;
1146
1147                         /* Report this event if it looks OK */
1148                         event_count = propagate_sensor_report(s, &data[returned_events]);
1149
1150                         /* Lower flag */
1151                         sensor_info[s].report_pending = 0;
1152
1153                         /* Duplicate only if both cal & uncal are active */
1154                         if (sensor_info[s].type == SENSOR_TYPE_GYROSCOPE &&
1155                                         sensor_info[s].pair_idx && sensor_info[sensor_info[s].pair_idx].enabled != 0) {
1156                                         struct gyro_cal* gyro_data = (struct gyro_cal*) sensor_info[s].cal_data;
1157
1158                                         memcpy(&data[returned_events + event_count], &data[returned_events],
1159                                                         sizeof(struct sensors_event_t) * event_count);
1160
1161                                         uncal_start = returned_events + event_count;
1162                                         for (i = 0; i < event_count; i++) {
1163                                                 data[uncal_start + i].type = SENSOR_TYPE_GYROSCOPE_UNCALIBRATED;
1164                                                 data[uncal_start + i].sensor = sensor_info[s].pair_idx;
1165
1166                                                 data[uncal_start + i].data[0] = data[returned_events + i].data[0] + gyro_data->bias_x;
1167                                                 data[uncal_start + i].data[1] = data[returned_events + i].data[1] + gyro_data->bias_y;
1168                                                 data[uncal_start + i].data[2] = data[returned_events + i].data[2] + gyro_data->bias_z;
1169
1170                                                 data[uncal_start + i].uncalibrated_gyro.bias[0] = gyro_data->bias_x;
1171                                                 data[uncal_start + i].uncalibrated_gyro.bias[1] = gyro_data->bias_y;
1172                                                 data[uncal_start + i].uncalibrated_gyro.bias[2] = gyro_data->bias_z;
1173                                         }
1174                                         event_count <<= 1;
1175                         }
1176                         sensor_info[sensor_info[s].pair_idx].report_pending = 0;
1177                         returned_events += event_count;
1178                         /*
1179                          * If the sample was deemed invalid or unreportable,
1180                          * e.g. had the same value as the previously reported
1181                          * value for a 'on change' sensor, silently drop it.
1182                          */
1183                 }
1184                 while (sensor_info[s].meta_data_pending) {
1185                         /* See sensors.h on these */
1186                         data[returned_events].version = META_DATA_VERSION;
1187                         data[returned_events].sensor = 0;
1188                         data[returned_events].type = SENSOR_TYPE_META_DATA;
1189                         data[returned_events].reserved0 = 0;
1190                         data[returned_events].timestamp = 0;
1191                         data[returned_events].meta_data.sensor = s;
1192                         data[returned_events].meta_data.what = META_DATA_FLUSH_COMPLETE;
1193                         returned_events++;
1194                         sensor_info[s].meta_data_pending--;
1195                 }
1196         }
1197         if (returned_events)
1198                 return returned_events;
1199
1200 await_event:
1201
1202         ALOGV("Awaiting sensor data\n");
1203
1204         nfds = epoll_wait(poll_fd, ev, MAX_DEVICES, get_poll_wait_timeout());
1205
1206         if (nfds == -1) {
1207                 ALOGE("epoll_wait returned -1 (%s)\n", strerror(errno));
1208                 goto await_event;
1209         }
1210
1211         ALOGV("%d fds signalled\n", nfds);
1212
1213         /* For each of the signalled sources */
1214         for (i=0; i<nfds; i++)
1215                 if (ev[i].events == EPOLLIN)
1216                         switch (ev[i].data.u32) {
1217                                 case 0 ... MAX_DEVICES-1:
1218                                         /* Read report from iio char dev fd */
1219                                         integrate_device_report(ev[i].data.u32);
1220                                         break;
1221
1222                                 case THREAD_REPORT_TAG_BASE ...
1223                                      THREAD_REPORT_TAG_BASE + MAX_SENSORS-1:
1224                                         /* Get report from acquisition thread */
1225                                         integrate_thread_report(ev[i].data.u32);
1226                                         break;
1227
1228                                 default:
1229                                         ALOGW("Unexpected event source!\n");
1230                                         break;
1231                         }
1232
1233         goto return_available_sensor_reports;
1234 }
1235
1236
1237 static void tentative_switch_trigger (int s)
1238 {
1239         /*
1240          * Under certain situations it may be beneficial to use an alternate
1241          * trigger:
1242          *
1243          * - for applications using the accelerometer with high sampling rates,
1244          *   prefer the continuous trigger over the any-motion one, to avoid
1245          *   jumps related to motion thresholds
1246          */
1247
1248         if (is_fast_accelerometer(s) &&
1249                 !(sensor_info[s].quirks & QUIRK_TERSE_DRIVER) &&
1250                         sensor_info[s].selected_trigger ==
1251                                 sensor_info[s].motion_trigger_name)
1252                 setup_trigger(s, sensor_info[s].init_trigger_name);
1253 }
1254
1255
1256 int sensor_set_delay(int s, int64_t ns)
1257 {
1258         /* Set the rate at which a specific sensor should report events */
1259
1260         /* See Android sensors.h for indication on sensor trigger modes */
1261
1262         char sysfs_path[PATH_MAX];
1263         char avail_sysfs_path[PATH_MAX];
1264         int dev_num             =       sensor_info[s].dev_num;
1265         int i                   =       sensor_info[s].catalog_index;
1266         const char *prefix      =       sensor_catalog[i].tag;
1267         float new_sampling_rate; /* Granted sampling rate after arbitration   */
1268         float cur_sampling_rate; /* Currently used sampling rate              */
1269         int per_sensor_sampling_rate;
1270         int per_device_sampling_rate;
1271         int32_t min_delay_us = sensor_desc[s].minDelay;
1272         max_delay_t max_delay_us = sensor_desc[s].maxDelay;
1273         float min_supported_rate = max_delay_us ? (1000000.0 / max_delay_us) : 1;
1274         float max_supported_rate =
1275                 (min_delay_us && min_delay_us != -1) ? (1000000.0 / min_delay_us) : 0;
1276         char freqs_buf[100];
1277         char* cursor;
1278         int n;
1279         float sr;
1280
1281         if (ns <= 0) {
1282                 ALOGE("Rejecting non-positive delay request on sensor %d, required delay: %lld\n", s, ns);
1283                 return -EINVAL;
1284         }
1285
1286         new_sampling_rate = 1000000000LL/ns;
1287
1288         ALOGV("Entering set delay S%d (%s): old rate(%f), new rate(%f)\n",
1289                 s, sensor_info[s].friendly_name, sensor_info[s].sampling_rate,
1290                 new_sampling_rate);
1291
1292         /*
1293          * Artificially limit ourselves to 1 Hz or higher. This is mostly to
1294          * avoid setting up the stage for divisions by zero.
1295          */
1296         if (new_sampling_rate < min_supported_rate)
1297                 new_sampling_rate = min_supported_rate;
1298
1299         if (max_supported_rate &&
1300                 new_sampling_rate > max_supported_rate) {
1301                 new_sampling_rate = max_supported_rate;
1302         }
1303
1304         sensor_info[s].sampling_rate = new_sampling_rate;
1305
1306         /* If we're dealing with a poll-mode sensor */
1307         if (!sensor_info[s].num_channels) {
1308                 /* Interrupt current sleep so the new sampling gets used */
1309                 pthread_cond_signal(&thread_release_cond[s]);
1310                 return 0;
1311         }
1312
1313         sprintf(sysfs_path, SENSOR_SAMPLING_PATH, dev_num, prefix);
1314
1315         if (sysfs_read_float(sysfs_path, &cur_sampling_rate) != -1) {
1316                 per_sensor_sampling_rate = 1;
1317                 per_device_sampling_rate = 0;
1318         } else {
1319                 per_sensor_sampling_rate = 0;
1320
1321                 sprintf(sysfs_path, DEVICE_SAMPLING_PATH, dev_num);
1322
1323                 if (sysfs_read_float(sysfs_path, &cur_sampling_rate) != -1)
1324                         per_device_sampling_rate = 1;
1325                 else
1326                         per_device_sampling_rate = 0;
1327         }
1328
1329         if (!per_sensor_sampling_rate && !per_device_sampling_rate) {
1330                 ALOGE("No way to adjust sampling rate on sensor %d\n", s);
1331                 return -ENOSYS;
1332         }
1333
1334         /* Coordinate with others active sensors on the same device, if any */
1335         if (per_device_sampling_rate)
1336                 for (n=0; n<sensor_count; n++)
1337                         if (n != s && sensor_info[n].dev_num == dev_num &&
1338                             sensor_info[n].num_channels &&
1339                             sensor_info[n].enabled &&
1340                             sensor_info[n].sampling_rate > new_sampling_rate)
1341                                 new_sampling_rate= sensor_info[n].sampling_rate;
1342
1343         /* Check if we have contraints on allowed sampling rates */
1344
1345         sprintf(avail_sysfs_path, DEVICE_AVAIL_FREQ_PATH, dev_num);
1346
1347         if (sysfs_read_str(avail_sysfs_path, freqs_buf, sizeof(freqs_buf)) > 0){
1348                 cursor = freqs_buf;
1349
1350                 /* Decode allowed sampling rates string, ex: "10 20 50 100" */
1351
1352                 /* While we're not at the end of the string */
1353                 while (*cursor && cursor[0]) {
1354
1355                         /* Decode a single value */
1356                         sr = strtod(cursor, NULL);
1357
1358                         /* If this matches the selected rate, we're happy */
1359                         if (new_sampling_rate == sr)
1360                                 break;
1361
1362                         /*
1363                          * If we reached a higher value than the desired rate,
1364                          * adjust selected rate so it matches the first higher
1365                          * available one and stop parsing - this makes the
1366                          * assumption that rates are sorted by increasing value
1367                          * in the allowed frequencies string.
1368                          */
1369                         if (sr > new_sampling_rate) {
1370                                 new_sampling_rate = sr;
1371                                 break;
1372                         }
1373
1374                         /* Skip digits */
1375                         while (cursor[0] && !isspace(cursor[0]))
1376                                 cursor++;
1377
1378                         /* Skip spaces */
1379                         while (cursor[0] && isspace(cursor[0]))
1380                                         cursor++;
1381                 }
1382         }
1383
1384         if (max_supported_rate &&
1385                 new_sampling_rate > max_supported_rate) {
1386                 new_sampling_rate = max_supported_rate;
1387         }
1388
1389         /* If the desired rate is already active we're all set */
1390         if (new_sampling_rate == cur_sampling_rate)
1391                 return 0;
1392
1393         ALOGI("Sensor %d sampling rate set to %g\n", s, new_sampling_rate);
1394
1395         if (trig_sensors_per_dev[dev_num])
1396                 enable_buffer(dev_num, 0);
1397
1398         sysfs_write_float(sysfs_path, new_sampling_rate);
1399
1400         /* Check if it makes sense to use an alternate trigger */
1401         tentative_switch_trigger(s);
1402
1403         if (trig_sensors_per_dev[dev_num])
1404                 enable_buffer(dev_num, 1);
1405
1406         return 0;
1407 }
1408
1409 int sensor_flush (int s)
1410 {
1411         /* If one shot or not enabled return -EINVAL */
1412         if (sensor_desc[s].flags & SENSOR_FLAG_ONE_SHOT_MODE ||
1413                 sensor_info[s].enabled == 0)
1414                 return -EINVAL;
1415
1416         sensor_info[s].meta_data_pending++;
1417         return 0;
1418 }
1419
1420 int allocate_control_data (void)
1421 {
1422         int i;
1423
1424         for (i=0; i<MAX_DEVICES; i++)
1425                 device_fd[i] = -1;
1426
1427         poll_fd = epoll_create(MAX_DEVICES);
1428
1429         if (poll_fd == -1) {
1430                 ALOGE("Can't create epoll instance for iio sensors!\n");
1431                 return -1;
1432         }
1433
1434         return poll_fd;
1435 }
1436
1437
1438 void delete_control_data (void)
1439 {
1440 }