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 <sys/epoll.h>
   9 #include <sys/socket.h>
  10 #include <utils/Log.h>
  11 #include <hardware/sensors.h>
  12 #include "control.h"
  13 #include "enumeration.h"
  14 #include "utils.h"
  15 #include "transform.h"
  16 #include "calibration.h"
  17
  18 /* Currently active sensors count, per device */
  19 static int poll_sensors_per_dev[MAX_DEVICES];   /* poll-mode sensors */
  20 static int trig_sensors_per_dev[MAX_DEVICES];   /* trigger, event based */
  21
  22 static int device_fd[MAX_DEVICES];   /* fd on the /dev/iio:deviceX file */
  23
  24 static int poll_fd; /* epoll instance covering all enabled sensors */
  25
  26 static int poll_socket_pair[2]; /* used to unblock the poll loop */
  27
  28 /* Timestamp for the moment when we last exited a poll operation */
  29 static int64_t last_poll_exit_ts;
  30
  31 static int active_poll_sensors; /* Number of enabled poll-mode sensors */
  32
  33 #define INVALID_DEV_NUM ((uint32_t) -1)
  34
  35
  36 static int enable_buffer(int dev_num, int enabled)
  37 {
  38         char sysfs_path[PATH_MAX];
  39
  40         sprintf(sysfs_path, ENABLE_PATH, dev_num);
  41
  42         /* Low level, non-multiplexed, enable/disable routine */
  43         return sysfs_write_int(sysfs_path, enabled);
  44 }
  45
  46
  47 static int setup_trigger(int dev_num, const char* trigger_val)
  48 {
  49         char sysfs_path[PATH_MAX];
  50
  51         sprintf(sysfs_path, TRIGGER_PATH, dev_num);
  52
  53         return sysfs_write_str(sysfs_path, trigger_val);
  54 }
  55
  56
  57 void build_sensor_report_maps(int dev_num)
  58 {
  59         /*
  60          * Read sysfs files from a iio device's scan_element directory, and
  61          * build a couple of tables from that data. These tables will tell, for
  62          * each sensor, where to gather relevant data in a device report, i.e.
  63          * the structure that we read from the /dev/iio:deviceX file in order to
  64          * sensor report, itself being the data that we return to Android when a
  65          * sensor poll completes. The mapping should be straightforward in the
  66          * case where we have a single sensor active per iio device but, this is
  67          * not the general case. In general several sensors can be handled
  68          * through a single iio device, and the _en, _index and _type syfs
  69          * entries all concur to paint a picture of what the structure of the
  70          * device report is.
  71          */
  72
  73         int s;
  74         int c;
  75         int n;
  76         int i;
  77         int ch_index;
  78         char* ch_spec;
  79         char spec_buf[MAX_TYPE_SPEC_LEN];
  80         struct datum_info_t* ch_info;
  81         int size;
  82         char sysfs_path[PATH_MAX];
  83         int known_channels;
  84         int offset;
  85         int channel_size_from_index[MAX_SENSORS * MAX_CHANNELS] = { 0 };
  86         int sensor_handle_from_index[MAX_SENSORS * MAX_CHANNELS] = { 0 };
  87         int channel_number_from_index[MAX_SENSORS * MAX_CHANNELS] = { 0 };
  88
  89         known_channels = 0;
  90
  91         /* For each sensor that is linked to this device */
  92         for (s=0; s<sensor_count; s++) {
  93                 if (sensor_info[s].dev_num != dev_num)
  94                         continue;
  95
  96                 i = sensor_info[s].catalog_index;
  97
  98                 /* Read channel details through sysfs attributes */
  99                 for (c=0; c<sensor_info[s].num_channels; c++) {
 100
 101                         /* Read _type file */
 102                         sprintf(sysfs_path, CHANNEL_PATH "%s",
 103                                 sensor_info[s].dev_num,
 104                                 sensor_catalog[i].channel[c].type_path);
 105
 106                         n = sysfs_read_str(sysfs_path, spec_buf,
 107                                                 sizeof(spec_buf));
 108
 109                         if (n == -1) {
 110                                         ALOGW(  "Failed to read type: %s\n",
 111                                         sysfs_path);
 112                                         continue;
 113                                 }
 114
 115                         ch_spec = sensor_info[s].channel[c].type_spec;
 116
 117                         memcpy(ch_spec, spec_buf, sizeof(spec_buf));
 118
 119                         ch_info = &sensor_info[s].channel[c].type_info;
 120
 121                         size = decode_type_spec(ch_spec, ch_info);
 122
 123                         /* Read _index file */
 124                         sprintf(sysfs_path, CHANNEL_PATH "%s",
 125                                 sensor_info[s].dev_num,
 126                                 sensor_catalog[i].channel[c].index_path);
 127
 128                         n = sysfs_read_int(sysfs_path, &ch_index);
 129
 130                         if (n == -1) {
 131                                         ALOGW(  "Failed to read index: %s\n",
 132                                                 sysfs_path);
 133                                         continue;
 134                                 }
 135
 136                         if (ch_index >= MAX_SENSORS) {
 137                                 ALOGE("Index out of bounds!: %s\n", sysfs_path);
 138                                 continue;
 139                         }
 140
 141                         /* Record what this index is about */
 142
 143                         sensor_handle_from_index [ch_index] = s;
 144                         channel_number_from_index[ch_index] = c;
 145                         channel_size_from_index  [ch_index] = size;
 146
 147                         known_channels++;
 148                 }
 149
 150                 /* Turn on channels we're aware of */
 151                 for (c=0;c<sensor_info[s].num_channels; c++) {
 152                         sprintf(sysfs_path, CHANNEL_PATH "%s",
 153                                 sensor_info[s].dev_num,
 154                                 sensor_catalog[i].channel[c].en_path);
 155
 156                         sysfs_write_int(sysfs_path, 1);
 157                 }
 158         }
 159
 160         ALOGI("Found %d channels on iio device %d\n", known_channels, dev_num);
 161
 162         /*
 163          * Now that we know which channels are defined, their sizes and their
 164          * ordering, update channels offsets within device report. Note: there
 165          * is a possibility that several sensors share the same index, with
 166          * their data fields being isolated by masking and shifting as specified
 167          * through the real bits and shift values in type attributes. This case
 168          * is not currently supported. Also, the code below assumes no hole in
 169          * the sequence of indices, so it is dependent on discovery of all
 170          * sensors.
 171          */
 172          offset = 0;
 173          for (i=0; i<MAX_SENSORS * MAX_CHANNELS; i++) {
 174                 s =     sensor_handle_from_index[i];
 175                 c =     channel_number_from_index[i];
 176                 size =  channel_size_from_index[i];
 177
 178                 if (!size)
 179                         continue;
 180
 181                 ALOGI("S%d C%d : offset %d, size %d, type %s\n",
 182                       s, c, offset, size, sensor_info[s].channel[c].type_spec);
 183
 184                 sensor_info[s].channel[c].offset        = offset;
 185                 sensor_info[s].channel[c].size          = size;
 186
 187                 offset += size;
 188          }
 189 }
 190
 191
 192 int adjust_counters (int s, int enabled)
 193 {
 194         /*
 195          * Adjust counters based on sensor enable action. Return values are:
 196          * -1 if there's an inconsistency: abort action in this case
 197          *  0 if the operation was completed and we're all set
 198          *  1 if we toggled the state of the sensor and there's work left
 199          */
 200
 201         int dev_num = sensor_info[s].dev_num;
 202         int catalog_index = sensor_info[s].catalog_index;
 203         int sensor_type = sensor_catalog[catalog_index].type;
 204
 205         /* Refcount per sensor, in terms of enable count */
 206         if (enabled) {
 207                 ALOGI("Enabling sensor %d (iio device %d: %s)\n",
 208                         s, dev_num, sensor_info[s].friendly_name);
 209
 210                 sensor_info[s].enable_count++;
 211
 212                 if (sensor_info[s].enable_count != 1) {
 213                         return 0; /* The sensor was, and remains, in use */
 214                 } else {
 215                         if (sensor_type == SENSOR_TYPE_MAGNETIC_FIELD)
 216                                 compass_read_data(COMPASS_CALIBRATION_PATH);
 217
 218                         if (sensor_type == SENSOR_TYPE_GYROSCOPE)
 219                                 gyro_cal_init(&sensor_info[s]);
 220                 }
 221         } else {
 222                 if (sensor_info[s].enable_count == 0)
 223                         return -1; /* Spurious disable call */
 224
 225                 ALOGI("Disabling sensor %d (iio device %d: %s)\n", s, dev_num,
 226                       sensor_info[s].friendly_name);
 227
 228                 if (sensor_type == SENSOR_TYPE_MAGNETIC_FIELD)
 229                         compass_store_data(COMPASS_CALIBRATION_PATH);
 230
 231                 sensor_info[s].enable_count--;
 232
 233                 if (sensor_info[s].enable_count > 0)
 234                         return 0; /* The sensor was, and remains, in use */
 235
 236                 /* Sensor disabled, lower report available flag */
 237                 sensor_info[s].report_pending = 0;
 238         }
 239
 240         /* We changed the state of a sensor - adjust per iio device counters */
 241
 242         /* If this is a regular event-driven sensor */
 243         if (sensor_info[s].num_channels) {
 244
 245                         if (enabled)
 246                                 trig_sensors_per_dev[dev_num]++;
 247                         else
 248                                 trig_sensors_per_dev[dev_num]--;
 249
 250                         return 1;
 251                 }
 252
 253         if (enabled) {
 254                 active_poll_sensors++;
 255                 poll_sensors_per_dev[dev_num]++;
 256                 return 1;
 257         }
 258
 259         active_poll_sensors--;
 260         poll_sensors_per_dev[dev_num]--;
 261         return 1;
 262 }
 263
 264
 265 int sensor_activate(int s, int enabled)
 266 {
 267         char device_name[PATH_MAX];
 268         char trigger_name[MAX_NAME_SIZE + 16];
 269         int c;
 270         struct epoll_event ev = {0};
 271         int dev_fd;
 272         int ret;
 273         int dev_num = sensor_info[s].dev_num;
 274         int i = sensor_info[s].catalog_index;
 275         int is_poll_sensor = !sensor_info[s].num_channels;
 276
 277         ret = adjust_counters(s, enabled);
 278
 279         /* If the operation was neutral in terms of state, we're done */
 280         if (ret <= 0)
 281                 return ret;
 282
 283         if (!is_poll_sensor) {
 284
 285                 /* Stop sampling */
 286                 enable_buffer(dev_num, 0);
 287                 setup_trigger(dev_num, "\n");
 288
 289                 /* If there's at least one sensor enabled on this iio device */
 290                 if (trig_sensors_per_dev[dev_num]) {
 291                         sprintf(trigger_name, "%s-dev%d",
 292                                         sensor_info[s].internal_name, dev_num);
 293
 294                         /* Start sampling */
 295                         setup_trigger(dev_num, trigger_name);
 296                         enable_buffer(dev_num, 1);
 297                 }
 298         }
 299
 300         /*
 301          * Make sure we have a fd on the character device ; conversely, close
 302          * the fd if no one is using associated sensor anymore. The assumption
 303          * here is that the underlying driver will power on the relevant
 304          * hardware block while someone hold a fd on the device.
 305          */
 306         dev_fd = device_fd[dev_num];
 307
 308         if (!enabled) {
 309                 if (dev_fd != -1 && !poll_sensors_per_dev[dev_num] &&
 310                         !trig_sensors_per_dev[dev_num]) {
 311                                 /*
 312                                  * Stop watching this fd. This should be a no-op
 313                                  * in case this fd was not in the poll set.
 314                                  */
 315                                 epoll_ctl(poll_fd, EPOLL_CTL_DEL, dev_fd, NULL);
 316
 317                                 close(dev_fd);
 318                                 device_fd[dev_num] = -1;
 319                         }
 320                 return 0;
 321         }
 322
 323         if (dev_fd == -1) {
 324                 /* First enabled sensor on this iio device */
 325                 sprintf(device_name, DEV_FILE_PATH, dev_num);
 326                 dev_fd = open(device_name, O_RDONLY | O_NONBLOCK);
 327
 328                 device_fd[dev_num] = dev_fd;
 329
 330                 if (dev_fd == -1) {
 331                         ALOGE("Could not open fd on %s (%s)\n",
 332                               device_name, strerror(errno));
 333                         adjust_counters(s, 0);
 334                         return -1;
 335                 }
 336
 337                 ALOGV("Opened %s: fd=%d\n", device_name, dev_fd);
 338
 339                 if (!is_poll_sensor) {
 340
 341                         /* Add this iio device fd to the set of watched fds */
 342                         ev.events = EPOLLIN;
 343                         ev.data.u32 = dev_num;
 344
 345                         ret = epoll_ctl(poll_fd, EPOLL_CTL_ADD, dev_fd, &ev);
 346
 347                         if (ret == -1) {
 348                                 ALOGE(  "Failed adding %d to poll set (%s)\n",
 349                                         dev_fd, strerror(errno));
 350                                 return -1;
 351                         }
 352
 353                         /* Note: poll-mode fds are not readable */
 354                 }
 355         }
 356
 357         /* Release the polling loop so an updated timeout gets used */
 358         write(poll_socket_pair[1], "", 1);
 359
 360         return 0;
 361 }
 362
 363
 364 static int integrate_device_report(int dev_num)
 365 {
 366         int len;
 367         int s,c;
 368         unsigned char buf[MAX_SENSOR_REPORT_SIZE] = { 0 };
 369         int sr_offset;
 370         unsigned char *target;
 371         unsigned char *source;
 372         int size;
 373         int ts;
 374
 375         /* There's an incoming report on the specified fd */
 376
 377         if (dev_num < 0 || dev_num >= MAX_DEVICES) {
 378                 ALOGE("Event reported on unexpected iio device %d\n", dev_num);
 379                 return -1;
 380         }
 381
 382         if (device_fd[dev_num] == -1) {
 383                 ALOGE("Ignoring stale report on iio device %d\n", dev_num);
 384                 return -1;
 385         }
 386
 387         ts = get_timestamp();
 388
 389         len = read(device_fd[dev_num], buf, MAX_SENSOR_REPORT_SIZE);
 390
 391         if (len == -1) {
 392                 ALOGE("Could not read report from iio device %d (%s)\n",
 393                       dev_num, strerror(errno));
 394                 return -1;
 395         }
 396
 397         ALOGV("Read %d bytes from iio device %d\n", len, dev_num);
 398
 399         for (s=0; s<MAX_SENSORS; s++)
 400                 if (sensor_info[s].dev_num == dev_num &&
 401                     sensor_info[s].enable_count) {
 402
 403                         sr_offset = 0;
 404
 405                         /* Copy data from device to sensor report buffer */
 406                         for (c=0; c<sensor_info[s].num_channels; c++) {
 407
 408                                 target = sensor_info[s].report_buffer +
 409                                         sr_offset;
 410
 411                                 source = buf + sensor_info[s].channel[c].offset;
 412
 413                                 size = sensor_info[s].channel[c].size;
 414
 415                                 memcpy(target, source, size);
 416
 417                                 sr_offset += size;
 418                         }
 419
 420                         ALOGV("Sensor %d report available (%d bytes)\n", s,
 421                               sr_offset);
 422
 423                         sensor_info[s].report_ts = ts;
 424                         sensor_info[s].report_pending = 1;
 425                 }
 426
 427         return 0;
 428 }
 429
 430
 431 static void propagate_sensor_report(int s, struct sensors_event_t* data)
 432 {
 433         /* There's a sensor report pending for this sensor ; transmit it */
 434
 435         int catalog_index = sensor_info[s].catalog_index;
 436         int sensor_type = sensor_catalog[catalog_index].type;
 437         int num_fields;
 438         int c;
 439         unsigned char* current_sample;
 440         int64_t current_ts = get_timestamp();
 441
 442         memset(data, 0, sizeof(sensors_event_t));
 443
 444         data->version = sizeof(sensors_event_t);
 445         data->sensor = s;
 446         data->type = sensor_type;
 447
 448         if (sensor_info[s].report_ts)
 449                 data->timestamp = sensor_info[s].report_ts;
 450         else
 451                 data->timestamp = current_ts;
 452
 453         switch (sensor_type) {
 454                 case SENSOR_TYPE_ACCELEROMETER:         /* m/s^2        */
 455                 case SENSOR_TYPE_MAGNETIC_FIELD:        /* micro-tesla  */
 456                 case SENSOR_TYPE_ORIENTATION:           /* degrees      */
 457                 case SENSOR_TYPE_GYROSCOPE:             /* radians/s    */
 458                         num_fields = 3;
 459                         break;
 460
 461                 case SENSOR_TYPE_LIGHT:                 /* SI lux units */
 462                 case SENSOR_TYPE_AMBIENT_TEMPERATURE:   /* °C          */
 463                 case SENSOR_TYPE_TEMPERATURE:           /* °C          */
 464                 case SENSOR_TYPE_PROXIMITY:             /* centimeters  */
 465                 case SENSOR_TYPE_PRESSURE:              /* hecto-pascal */
 466                 case SENSOR_TYPE_RELATIVE_HUMIDITY:     /* percent */
 467                         num_fields = 1;
 468                         break;
 469
 470                 case SENSOR_TYPE_ROTATION_VECTOR:
 471                         num_fields = 4;
 472                         break;
 473
 474                 case SENSOR_TYPE_DEVICE_PRIVATE_BASE:   /* hidden for now */
 475                         num_fields = 0;
 476                         break;
 477
 478                 default:
 479                         ALOGE("Unknown sensor type!\n");
 480                         num_fields = 0;
 481                         break;
 482         }
 483
 484         ALOGV("Sample on sensor %d (type %d):\n", s, sensor_type);
 485
 486         /* Take note of current time counter value for rate control purposes */
 487         sensor_info[s].last_integration_ts = current_ts;
 488
 489         /* If we're dealing with a poll-mode sensor */
 490         if (!sensor_info[s].num_channels) {
 491
 492                 /* Read values through sysfs rather than from a report buffer */
 493                 for (c=0; c<num_fields; c++) {
 494
 495                         data->data[c] = acquire_immediate_value(s, c);
 496
 497                         ALOGV("\tfield %d: %f\n", c, data->data[c]);
 498                 }
 499
 500                 sensor_info[s].ops.finalize(s, data);
 501                 return;
 502         }
 503
 504         /* Convert the data into the expected Android-level format */
 505
 506         current_sample = sensor_info[s].report_buffer;
 507
 508         for (c=0; c<num_fields; c++) {
 509
 510                 data->data[c] = sensor_info[s].ops.transform
 511                                                         (s, c, current_sample);
 512
 513                 ALOGV("\tfield %d: %f\n", c, data->data[c]);
 514                 current_sample += sensor_info[s].channel[c].size;
 515         }
 516
 517         sensor_info[s].ops.finalize(s, data);
 518 }
 519
 520
 521 static int get_poll_time (void)
 522 {
 523         int64_t target_ts;
 524         int64_t lowest_target_ts;
 525         int64_t current_ts;
 526         int s;
 527
 528         if (!active_poll_sensors)
 529                 return -1;      /* Infinite wait */
 530
 531         /* Check if we should schedule a poll-mode sensor event delivery */
 532
 533         lowest_target_ts = INT64_MAX;
 534
 535         for (s=0; s<sensor_count; s++)
 536                 if (sensor_info[s].enable_count &&
 537                     sensor_info[s].sampling_rate &&
 538                     !sensor_info[s].num_channels) {
 539                                 target_ts = sensor_info[s].last_integration_ts +
 540                                       1000000000LL/sensor_info[s].sampling_rate;
 541
 542                                 if (target_ts < lowest_target_ts)
 543                                         lowest_target_ts = target_ts;
 544                         }
 545
 546         if (lowest_target_ts == INT64_MAX)
 547                 return -1;
 548
 549         current_ts = get_timestamp();
 550
 551         if (lowest_target_ts <= current_ts)
 552                 return 0;
 553
 554         return (lowest_target_ts - current_ts)/1000000; /* ms */
 555 }
 556
 557
 558 static void acknowledge_release (void)
 559 {
 560         /* A write to our socket circuit was performed to release epoll */
 561         char buf;
 562         read(poll_socket_pair[0], &buf, 1);
 563 }
 564
 565
 566 int sensor_poll(struct sensors_event_t* data, int count)
 567 {
 568         int s;
 569         int i;
 570         int nfds;
 571         int delta;
 572         struct epoll_event ev[MAX_DEVICES];
 573         int64_t target_ts;
 574
 575         /* Get one or more events from our collection of sensors */
 576
 577 return_first_available_sensor_report:
 578
 579         /* If there's at least one available report */
 580         for (s=0; s<sensor_count; s++)
 581                 if (sensor_info[s].report_pending) {
 582
 583                         /* Return that up */
 584                         propagate_sensor_report(s, data);
 585                         sensor_info[s].report_pending = 0;
 586                         ALOGV("Report on sensor %d\n", s);
 587                         return 1;
 588                 }
 589 await_event:
 590
 591         ALOGV("Awaiting sensor data\n");
 592
 593         nfds = epoll_wait(poll_fd, ev, MAX_DEVICES, get_poll_time());
 594
 595         last_poll_exit_ts = get_timestamp();
 596
 597         if (nfds == -1) {
 598                 ALOGI("epoll_wait returned -1 (%s)\n", strerror(errno));
 599                 goto await_event;
 600         }
 601
 602         ALOGV("%d fds signalled\n", nfds);
 603
 604         /* For each of the devices for which a report is available */
 605         for (i=0; i<nfds; i++)
 606                 if (ev[i].events == EPOLLIN) {
 607                         if (ev[i].data.u32 == INVALID_DEV_NUM) {
 608                                 acknowledge_release();
 609                                 goto await_event;
 610                         } else
 611                                 /* Read report */
 612                                 integrate_device_report(ev[i].data.u32);
 613                 }
 614
 615         /* Check poll-mode sensors and fire up an event if it's time to do so */
 616         if (active_poll_sensors)
 617                 for (s=0; s<sensor_count; s++)
 618                         if (sensor_info[s].enable_count &&
 619                             !sensor_info[s].num_channels &&
 620                             sensor_info[s].sampling_rate) {
 621                                 target_ts = sensor_info[s].last_integration_ts +
 622                                       1000000000LL/sensor_info[s].sampling_rate;
 623
 624                                 if (last_poll_exit_ts >= target_ts)
 625                                         sensor_info[s].report_pending = 1;
 626                         }
 627
 628         goto return_first_available_sensor_report;
 629 }
 630
 631
 632 int sensor_set_delay(int s, int64_t ns)
 633 {
 634         /* Set the rate at which a specific sensor should report events */
 635
 636         /* See Android sensors.h for indication on sensor trigger modes */
 637
 638         char sysfs_path[PATH_MAX];
 639         char avail_sysfs_path[PATH_MAX];
 640         int dev_num             =       sensor_info[s].dev_num;
 641         int i                   =       sensor_info[s].catalog_index;
 642         const char *prefix      =       sensor_catalog[i].tag;
 643         int new_sampling_rate;  /* Granted sampling rate after arbitration   */
 644         int cur_sampling_rate;  /* Currently used sampling rate              */
 645         int req_sampling_rate;  /* Requested ; may be different from granted */
 646         int per_sensor_sampling_rate;
 647         int per_device_sampling_rate;
 648         int max_supported_rate = 0;
 649         char freqs_buf[100];
 650         char* cursor;
 651         int n;
 652
 653         if (!ns) {
 654                 ALOGE("Rejecting zero delay request on sensor %d\n", s);
 655                 return -EINVAL;
 656         }
 657
 658         new_sampling_rate = req_sampling_rate = (int) (1000000000L/ns);
 659
 660         if (!new_sampling_rate) {
 661                 ALOGI("Sub-HZ sampling rate requested on on sensor %d\n", s);
 662                 new_sampling_rate = 1;
 663         }
 664
 665         sensor_info[s].sampling_rate = new_sampling_rate;
 666
 667         /* If we're dealing with a poll-mode sensor, release poll and return */
 668         if (!sensor_info[s].num_channels)
 669                 goto exit;
 670
 671         sprintf(sysfs_path, SENSOR_SAMPLING_PATH, dev_num, prefix);
 672
 673         if (sysfs_read_int(sysfs_path, &cur_sampling_rate) != -1) {
 674                 per_sensor_sampling_rate = 1;
 675                 per_device_sampling_rate = 0;
 676         } else {
 677                 per_sensor_sampling_rate = 0;
 678
 679                 sprintf(sysfs_path, DEVICE_SAMPLING_PATH, dev_num);
 680
 681                 if (sysfs_read_int(sysfs_path, &cur_sampling_rate) != -1)
 682                         per_device_sampling_rate = 1;
 683                 else
 684                         per_device_sampling_rate = 0;
 685         }
 686
 687         if (!per_sensor_sampling_rate && !per_device_sampling_rate) {
 688                 ALOGE("No way to adjust sampling rate on sensor %d\n", s);
 689                 return -ENOSYS;
 690         }
 691
 692         /* Coordinate with others active sensors on the same device, if any */
 693         if (per_device_sampling_rate)
 694                 for (n=0; n<sensor_count; n++)
 695                         if (n != s && sensor_info[n].dev_num == dev_num &&
 696                             sensor_info[n].num_channels &&
 697                             sensor_info[n].enable_count &&
 698                             sensor_info[n].sampling_rate > new_sampling_rate)
 699                                 new_sampling_rate= sensor_info[n].sampling_rate;
 700
 701         /* Check if we have contraints on allowed sampling rates */
 702
 703         sprintf(avail_sysfs_path, DEVICE_AVAIL_FREQ_PATH, dev_num);
 704
 705         if (sysfs_read_str(avail_sysfs_path, freqs_buf, sizeof(freqs_buf)) > 0){
 706                 cursor = freqs_buf;
 707
 708                 /* Decode allowed sampling rates string, ex: "10 20 50 100" */
 709
 710                 /* While we're not at the end of the string */
 711                 while (*cursor && cursor[0]) {
 712
 713                         /* Decode a single integer value */
 714                         n = atoi(cursor);
 715
 716                         /* Cap sampling rate to CAP_SENSOR_MAX_FREQUENCY*/
 717                         if(n > CAP_SENSOR_MAX_FREQUENCY)
 718                                  break;
 719
 720                         if (n > max_supported_rate)
 721                                 max_supported_rate = n;
 722
 723                         /* If this matches the selected rate, we're happy */
 724                         if (new_sampling_rate == n)
 725                                 break;
 726
 727                         /*
 728                          * If we reached a higher value than the desired rate,
 729                          * adjust selected rate so it matches the first higher
 730                          * available one and stop parsing - this makes the
 731                          * assumption that rates are sorted by increasing value
 732                          * in the allowed frequencies string.
 733                          */
 734                         if (n > new_sampling_rate) {
 735                                 ALOGI(
 736                         "Increasing sampling rate on sensor %d from %d to %d\n",
 737                                 s, req_sampling_rate, n);
 738
 739                                 new_sampling_rate = n;
 740                                 break;
 741                         }
 742
 743                         /* Skip digits */
 744                         while (cursor[0] && !isspace(cursor[0]))
 745                                 cursor++;
 746
 747                         /* Skip spaces */
 748                         while (cursor[0] && isspace(cursor[0]))
 749                                         cursor++;
 750                 }
 751         }
 752
 753
 754         if (max_supported_rate &&
 755                 new_sampling_rate > max_supported_rate) {
 756                 new_sampling_rate = max_supported_rate;
 757                 ALOGI(  "Can't support %d sampling rate, lowering to %d\n",
 758                         req_sampling_rate, new_sampling_rate);
 759         }
 760
 761
 762         /* If the desired rate is already active we're all set */
 763         if (new_sampling_rate == cur_sampling_rate)
 764                 return 0;
 765
 766         ALOGI("Sensor %d sampling rate switched to %d\n", s, new_sampling_rate);
 767
 768         if (trig_sensors_per_dev[dev_num])
 769                 enable_buffer(dev_num, 0);
 770
 771         sysfs_write_int(sysfs_path, new_sampling_rate);
 772
 773         if (trig_sensors_per_dev[dev_num])
 774                 enable_buffer(dev_num, 1);
 775
 776 exit:
 777         /* Release the polling loop so an updated timeout value gets used */
 778         write(poll_socket_pair[1], "", 1);
 779
 780         return 0;
 781 }
 782
 783
 784
 785 int allocate_control_data (void)
 786 {
 787         int i;
 788         struct epoll_event ev = {0};
 789
 790         for (i=0; i<MAX_DEVICES; i++)
 791                 device_fd[i] = -1;
 792
 793         poll_fd = epoll_create(MAX_DEVICES);
 794
 795         if (poll_fd == -1) {
 796                 ALOGE("Can't create epoll instance for iio sensors!\n");
 797                 return -1;
 798         }
 799
 800         /* Create and add "unblocking" fd to the set of watched fds */
 801
 802         if (socketpair(AF_UNIX, SOCK_STREAM, 0, poll_socket_pair) == -1) {
 803                 ALOGE("Can't create socket pair for iio sensors!\n");
 804                 close(poll_fd);
 805                 return -1;
 806         }
 807
 808         ev.events = EPOLLIN;
 809         ev.data.u32 = INVALID_DEV_NUM;
 810
 811         epoll_ctl(poll_fd, EPOLL_CTL_ADD, poll_socket_pair[0], &ev);
 812
 813         return poll_fd;
 814 }
 815
 816
 817 void delete_control_data (void)
 818 {
 819 }