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
  17 /* Currently active sensors count, per device */
  18 static int poll_sensors_per_dev[MAX_DEVICES];   /* poll-mode sensors */
  19 static int trig_sensors_per_dev[MAX_DEVICES];   /* trigger, event based */
  20
  21 static int device_fd[MAX_DEVICES];   /* fd on the /dev/iio:deviceX file */
  22
  23 static int poll_fd; /* epoll instance covering all enabled sensors */
  24
  25 static int poll_socket_pair[2]; /* used to unblock the poll loop */
  26
  27 /* Timestamp for the moment when we last exited a poll operation */
  28 static int64_t last_poll_exit_ts;
  29
  30 static int active_poll_sensors; /* Number of enabled poll-mode sensors */
  31
  32 /* Cap the time between poll operations to this, to counter runaway polls */
  33 #define POLL_MIN_INTERVAL 10000 /* uS */
  34
  35 #define INVALID_DEV_NUM ((uint32_t) -1)
  36
  37
  38 static int enable_buffer(int dev_num, int enabled)
  39 {
  40         char sysfs_path[PATH_MAX];
  41
  42         sprintf(sysfs_path, ENABLE_PATH, dev_num);
  43
  44         /* Low level, non-multiplexed, enable/disable routine */
  45         return sysfs_write_int(sysfs_path, enabled);
  46 }
  47
  48
  49 static int setup_trigger(int dev_num, const char* trigger_val)
  50 {
  51         char sysfs_path[PATH_MAX];
  52
  53         sprintf(sysfs_path, TRIGGER_PATH, dev_num);
  54
  55         return sysfs_write_str(sysfs_path, trigger_val);
  56 }
  57
  58
  59 static void refresh_sensor_report_maps(int dev_num)
  60 {
  61         /*
  62          * Read sysfs files from a iio device's scan_element directory, and
  63          * build a couple of tables from that data. These tables will tell, for
  64          * each sensor, where to gather relevant data in a device report, i.e.
  65          * the structure that we read from the /dev/iio:deviceX file in order to
  66          * sensor report, itself being the data that we return to Android when a
  67          * sensor poll completes. The mapping should be straightforward in the
  68          * case where we have a single sensor active per iio device but, this is
  69          * not the general case. In general several sensors can be handled
  70          * through a single iio device, and the _en, _index and _type syfs
  71          * entries all concur to paint a picture of what the structure of the
  72          * device report is.
  73          */
  74
  75         int s;
  76         int c;
  77         int n;
  78         int i;
  79         int ch_enabled;
  80         int ch_index;
  81         char* ch_spec;
  82         char spec_buf[MAX_TYPE_SPEC_LEN];
  83         struct datum_info_t* ch_info;
  84         int size;
  85         char sysfs_path[PATH_MAX];
  86         int active_channels;
  87         int offset;
  88         int channel_count;
  89         int channel_size_from_index[MAX_SENSORS * MAX_CHANNELS] = { 0 };
  90         int sensor_handle_from_index[MAX_SENSORS * MAX_CHANNELS] = { 0 };
  91         int channel_number_from_index[MAX_SENSORS * MAX_CHANNELS] = { 0 };
  92
  93         active_channels = 0;
  94
  95         /* For each sensor that is linked to this device */
  96         for (s=0; s<sensor_count; s++) {
  97                 if (sensor_info[s].dev_num != dev_num)
  98                         continue;
  99
 100                 i = sensor_info[s].catalog_index;
 101
 102                 /* Read channel status through syfs attributes */
 103                 for (c=0; c<sensor_info[s].num_channels; c++) {
 104
 105                         /* Read _en file */
 106                         sprintf(sysfs_path, CHANNEL_PATH "%s",
 107                                 sensor_info[s].dev_num,
 108                                 sensor_catalog[i].channel[c].en_path);
 109
 110                         n = sysfs_read_int(sysfs_path, &ch_enabled);
 111
 112                         if (n == -1) {
 113                                 ALOGW(  "Failed to read _en flag: %s\n",
 114                                 sysfs_path);
 115                                 continue;
 116                         }
 117
 118                         if (!ch_enabled != 1) {
 119                                 sensor_info[s].channel[c].size = 0;
 120                         }
 121
 122                         /* Read _type file */
 123                         sprintf(sysfs_path, CHANNEL_PATH "%s",
 124                                 sensor_info[s].dev_num,
 125                                 sensor_catalog[i].channel[c].type_path);
 126
 127                         n = sysfs_read_str(sysfs_path, spec_buf,
 128                                                 sizeof(spec_buf));
 129
 130                         if (n == -1) {
 131                                         ALOGW(  "Failed to read type: %s\n",
 132                                         sysfs_path);
 133                                         continue;
 134                                 }
 135
 136                         ch_spec = sensor_info[s].channel[c].type_spec;
 137
 138                         memcpy(ch_spec, spec_buf, sizeof(spec_buf));
 139
 140                         ch_info = &sensor_info[s].channel[c].type_info;
 141
 142                         size = decode_type_spec(ch_spec, ch_info);
 143
 144                         /* Read _index file */
 145                         sprintf(sysfs_path, CHANNEL_PATH "%s",
 146                                 sensor_info[s].dev_num,
 147                                 sensor_catalog[i].channel[c].index_path);
 148
 149                         n = sysfs_read_int(sysfs_path, &ch_index);
 150
 151                         if (n == -1) {
 152                                         ALOGW(  "Failed to read index: %s\n",
 153                                                 sysfs_path);
 154                                         continue;
 155                                 }
 156
 157                         if (ch_index >= MAX_SENSORS) {
 158                                 ALOGE("Index out of bounds!: %s\n", sysfs_path);
 159                                 continue;
 160                         }
 161
 162                         /* Record what this index is about */
 163
 164                         sensor_handle_from_index [ch_index] = s;
 165                         channel_number_from_index[ch_index] = c;
 166                         channel_size_from_index  [ch_index] = size;
 167
 168                         active_channels++;
 169                 }
 170         }
 171
 172         ALOGI("Found %d enabled channels for iio device %d\n", active_channels,
 173                 dev_num);
 174
 175         /*
 176          * Now that we know which channels are enabled, their sizes and their
 177          * ordering, update channels offsets within device report. Note: there
 178          * is a possibility that several sensors share the same index, with
 179          * their data fields being isolated by masking and shifting as specified
 180          * through the real bits and shift values in type attributes. This case
 181          * is not currently supported. Also, the code below assumes no hole in
 182          * the sequence of indices, so it is dependent on discovery of all
 183          * sensors.
 184          */
 185          offset = 0;
 186          for (i=0; i<MAX_SENSORS * MAX_CHANNELS; i++) {
 187                 s =     sensor_handle_from_index[i];
 188                 c =     channel_number_from_index[i];
 189                 size =  channel_size_from_index[i];
 190
 191                 if (!size)
 192                         continue;
 193
 194                 ALOGI("S%d C%d : offset %d, size %d, type %s\n",
 195                       s, c, offset, size, sensor_info[s].channel[c].type_spec);
 196
 197                 sensor_info[s].channel[c].offset        = offset;
 198                 sensor_info[s].channel[c].size          = size;
 199
 200                 offset += size;
 201          }
 202 }
 203
 204
 205 int adjust_counters (int s, int enabled)
 206 {
 207         /*
 208          * Adjust counters based on sensor enable action. Return values are:
 209          * -1 if there's an inconsistency: abort action in this case
 210          *  0 if the operation was completed and we're all set
 211          *  1 if we toggled the state of the sensor and there's work left
 212          */
 213
 214         int dev_num = sensor_info[s].dev_num;
 215
 216         /* Refcount per sensor, in terms of enable count */
 217         if (enabled) {
 218                 ALOGI("Enabling sensor %d (iio device %d: %s)\n",
 219                         s, dev_num, sensor_info[s].friendly_name);
 220
 221                 sensor_info[s].enable_count++;
 222
 223                 if (sensor_info[s].enable_count != 1)
 224                         return 0; /* The sensor was, and remains, in use */
 225         } else {
 226                 if (sensor_info[s].enable_count == 0)
 227                         return -1; /* Spurious disable call */
 228
 229                 ALOGI("Disabling sensor %d (iio device %d: %s)\n", s, dev_num,
 230                       sensor_info[s].friendly_name);
 231
 232                 sensor_info[s].enable_count--;
 233
 234                 if (sensor_info[s].enable_count > 0)
 235                         return 0; /* The sensor was, and remains, in use */
 236
 237                 /* Sensor disabled, clear up pending data */
 238
 239                 sensor_info[s].report_pending = 0;
 240                 memset(sensor_info[s].report_buffer, 0, MAX_SENSOR_REPORT_SIZE);
 241         }
 242
 243         /* We changed the state of a sensor - adjust per iio device counters */
 244
 245         /* If this is a regular event-driven sensor */
 246         if (sensor_info[s].num_channels) {
 247
 248                         if (enabled)
 249                                 trig_sensors_per_dev[dev_num]++;
 250                         else
 251                                 trig_sensors_per_dev[dev_num]--;
 252
 253                         return 1;
 254                 }
 255
 256         if (enabled) {
 257                 active_poll_sensors++;
 258                 poll_sensors_per_dev[dev_num]++;
 259                 return 1;
 260         }
 261
 262         active_poll_sensors--;
 263         poll_sensors_per_dev[dev_num]--;
 264         return 1;
 265 }
 266
 267
 268 int sensor_activate(int s, int enabled)
 269 {
 270         char sysfs_path[PATH_MAX];
 271         char device_name[PATH_MAX];
 272         char trigger_name[MAX_NAME_SIZE + 16];
 273         int c;
 274         struct epoll_event ev = {0};
 275         int dev_fd;
 276         int ret;
 277         int dev_num = sensor_info[s].dev_num;
 278         int i = sensor_info[s].catalog_index;
 279         int is_poll_sensor = !sensor_info[s].num_channels;
 280
 281         ret = adjust_counters(s, enabled);
 282
 283         /* If the operation was neutral in terms of state, we're done */
 284         if (ret <= 0)
 285                 return ret;
 286
 287         if (!is_poll_sensor) {
 288                 /* Changes have to be made while the buffer is turned off */
 289                 enable_buffer(dev_num, 0);
 290
 291                 /* Configure trigger */
 292                 switch (trig_sensors_per_dev[dev_num]) {
 293                         case 0:
 294                                 setup_trigger(dev_num, "none");
 295                                 break;
 296
 297                         case 1:
 298                                 sprintf(trigger_name, "%s-dev%d",
 299                                         sensor_info[s].internal_name, dev_num);
 300
 301                                 setup_trigger(dev_num, trigger_name);
 302                                 break;
 303
 304                         default:
 305                                 /* The trigger is already set */
 306                                 break;
 307                 }
 308
 309                 /*
 310                  * Turn channels associated to this sensor on or off, and update
 311                  * the channels maps for all sensors associated to this device.
 312                  */
 313                 for (c=0;c<sensor_info[s].num_channels; c++) {
 314                         sprintf(sysfs_path, CHANNEL_PATH "%s",
 315                                 sensor_info[s].dev_num,
 316                                 sensor_catalog[i].channel[c].en_path);
 317
 318                         sysfs_write_int(sysfs_path, enabled);
 319                 }
 320
 321                 /* If there's at least one sensor left */
 322                 if (trig_sensors_per_dev[dev_num]) {
 323                         refresh_sensor_report_maps(dev_num);
 324                         enable_buffer(dev_num, 1);
 325                 }
 326         }
 327
 328         /*
 329          * Make sure we have a fd on the character device ; conversely, close
 330          * the fd if no one is using associated sensor anymore. The assumption
 331          * here is that the underlying driver will power on the relevant
 332          * hardware block while someone hold a fd on the device.
 333          */
 334         dev_fd = device_fd[dev_num];
 335
 336         if (!enabled) {
 337                 if (dev_fd != -1 && !poll_sensors_per_dev[dev_num] &&
 338                         !trig_sensors_per_dev[dev_num]) {
 339                                 /*
 340                                  * Stop watching this fd. This should be a no-op
 341                                  * in case this fd was not in the poll set.
 342                                  */
 343                                 epoll_ctl(poll_fd, EPOLL_CTL_DEL, dev_fd, NULL);
 344
 345                                 close(dev_fd);
 346                                 device_fd[dev_num] = -1;
 347                         }
 348                 return 0;
 349         }
 350
 351         if (dev_fd == -1) {
 352                 /* First enabled sensor on this iio device */
 353                 sprintf(device_name, DEV_FILE_PATH, dev_num);
 354                 dev_fd = open(device_name, O_RDONLY | O_NONBLOCK);
 355
 356                 device_fd[dev_num] = dev_fd;
 357
 358                 if (dev_fd == -1) {
 359                         ALOGE("Could not open fd on %s (%s)\n",
 360                               device_name, strerror(errno));
 361                         adjust_counters(s, 0);
 362                         return -1;
 363                 }
 364
 365                 ALOGV("Opened %s: fd=%d\n", device_name, dev_fd);
 366
 367                 if (!is_poll_sensor) {
 368
 369                         /* Add this iio device fd to the set of watched fds */
 370                         ev.events = EPOLLIN;
 371                         ev.data.u32 = dev_num;
 372
 373                         ret = epoll_ctl(poll_fd, EPOLL_CTL_ADD, dev_fd, &ev);
 374
 375                         if (ret == -1) {
 376                                 ALOGE(  "Failed adding %d to poll set (%s)\n",
 377                                         dev_fd, strerror(errno));
 378                                 return -1;
 379                         }
 380
 381                         /* Note: poll-mode fds are not readable */
 382                 }
 383         }
 384
 385         /* Release the polling loop so an updated timeout gets used */
 386         write(poll_socket_pair[1], "", 1);
 387
 388         return 0;
 389 }
 390
 391
 392 static int integrate_device_report(int dev_num)
 393 {
 394         int len;
 395         int s,c;
 396         unsigned char buf[MAX_SENSOR_REPORT_SIZE * MAX_SENSORS] = { 0 };
 397         int sr_offset;
 398         unsigned char *target;
 399         unsigned char *source;
 400         int size;
 401         int expected_size = 0;
 402
 403         /* There's an incoming report on the specified fd */
 404
 405         if (dev_num < 0 || dev_num >= MAX_DEVICES ||
 406                 !trig_sensors_per_dev[dev_num]) {
 407                 ALOGE("Event reported on unexpected iio device %d\n", dev_num);
 408                 return -1;
 409         }
 410
 411         for (s=0; s<MAX_SENSORS; s++)
 412                 if (sensor_info[s].dev_num == dev_num)
 413                         for (c=0; c<sensor_info[s].num_channels; c++)
 414                                 expected_size += sensor_info[s].channel[c].size;
 415
 416         len = read(device_fd[dev_num], buf, expected_size);
 417
 418         if (len == -1) {
 419                 ALOGE("Could not read report from iio device %d (%s)\n",
 420                       dev_num, strerror(errno));
 421                 return -1;
 422         }
 423
 424         ALOGV("Read %d bytes from iio device %d\n", len, dev_num);
 425
 426         for (s=0; s<MAX_SENSORS; s++)
 427                 if (sensor_info[s].dev_num == dev_num) {
 428                         sr_offset = 0;
 429
 430                         /* Copy data from device to sensor report buffer */
 431                         for (c=0; c<sensor_info[s].num_channels; c++) {
 432
 433                                 target = sensor_info[s].report_buffer +
 434                                         sr_offset;
 435
 436                                 source = buf + sensor_info[s].channel[c].offset;
 437
 438                                 size = sensor_info[s].channel[c].size;
 439
 440                                 memcpy(target, source, size);
 441
 442                                 sr_offset += size;
 443                         }
 444
 445                         if (sensor_info[s].enable_count) {
 446                                 ALOGV("Sensor %d report available (%d bytes)\n",
 447                                       s, sr_offset);
 448
 449                                 sensor_info[s].report_pending = 1;
 450                         }
 451                 }
 452
 453         return 0;
 454 }
 455
 456
 457 static void propagate_sensor_report(int s, struct sensors_event_t* data)
 458 {
 459         /* There's a sensor report pending for this sensor ; transmit it */
 460
 461         int catalog_index = sensor_info[s].catalog_index;
 462         int sensor_type = sensor_catalog[catalog_index].type;
 463         int num_fields;
 464         int c;
 465         unsigned char* current_sample;
 466
 467         memset(data, 0, sizeof(sensors_event_t));
 468
 469         data->version = sizeof(sensors_event_t);
 470         data->sensor = s;
 471         data->type = sensor_type;
 472         data->timestamp = get_timestamp();
 473
 474         switch (sensor_type) {
 475                 case SENSOR_TYPE_ACCELEROMETER:         /* m/s^2        */
 476                 case SENSOR_TYPE_MAGNETIC_FIELD:        /* micro-tesla  */
 477                 case SENSOR_TYPE_ORIENTATION:           /* degrees      */
 478                 case SENSOR_TYPE_GYROSCOPE:             /* radians/s    */
 479                         num_fields = 3;
 480                         break;
 481
 482                 case SENSOR_TYPE_LIGHT:                 /* SI lux units */
 483                 case SENSOR_TYPE_AMBIENT_TEMPERATURE:   /* °C          */
 484                 case SENSOR_TYPE_TEMPERATURE:           /* °C          */
 485                 case SENSOR_TYPE_PROXIMITY:             /* centimeters  */
 486                 case SENSOR_TYPE_PRESSURE:              /* hecto-pascal */
 487                 case SENSOR_TYPE_RELATIVE_HUMIDITY:     /* percent */
 488                         num_fields = 1;
 489                         break;
 490
 491                 case SENSOR_TYPE_ROTATION_VECTOR:
 492                         num_fields = 4;
 493                         break;
 494
 495                 case SENSOR_TYPE_DEVICE_PRIVATE_BASE:   /* hidden for now */
 496                         num_fields = 0;
 497                         break;
 498
 499                 default:
 500                         ALOGE("Unknown sensor type!\n");
 501                         num_fields = 0;
 502                         break;
 503         }
 504
 505         ALOGV("Sample on sensor %d (type %d):\n", s, sensor_type);
 506
 507         /* Take note of current time counter value for rate control purposes */
 508         sensor_info[s].last_integration_ts = get_timestamp();
 509
 510         /* If we're dealing with a poll-mode sensor */
 511         if (!sensor_info[s].num_channels) {
 512
 513                 /* Read values through sysfs rather than from a report buffer */
 514                 for (c=0; c<num_fields; c++) {
 515
 516                         data->data[c] = acquire_immediate_value(s, c);
 517
 518                         ALOGV("\tfield %d: %f\n", c, data->data[c]);
 519                 }
 520
 521                 sensor_info[s].ops.finalize(s, data);
 522                 return;
 523         }
 524
 525         /* Convert the data into the expected Android-level format */
 526
 527         current_sample = sensor_info[s].report_buffer;
 528
 529         for (c=0; c<num_fields; c++) {
 530
 531                 data->data[c] = sensor_info[s].ops.transform
 532                                                         (s, c, current_sample);
 533
 534                 ALOGV("\tfield %d: %f\n", c, data->data[c]);
 535                 current_sample += sensor_info[s].channel[c].size;
 536         }
 537
 538         sensor_info[s].ops.finalize(s, data);
 539 }
 540
 541
 542 static int get_poll_time (void)
 543 {
 544         int64_t target_ts;
 545         int64_t lowest_target_ts;
 546         int64_t current_ts;
 547         int s;
 548
 549         if (!active_poll_sensors)
 550                 return -1;      /* Infinite wait */
 551
 552         /* Check if we should schedule a poll-mode sensor event delivery */
 553
 554         lowest_target_ts = INT64_MAX;
 555
 556         for (s=0; s<sensor_count; s++)
 557                 if (sensor_info[s].enable_count &&
 558                     sensor_info[s].sampling_rate &&
 559                     !sensor_info[s].num_channels) {
 560                                 target_ts = sensor_info[s].last_integration_ts +
 561                                       1000000000LL/sensor_info[s].sampling_rate;
 562
 563                                 if (target_ts < lowest_target_ts)
 564                                         lowest_target_ts = target_ts;
 565                         }
 566
 567         if (lowest_target_ts == INT64_MAX)
 568                 return -1;
 569
 570         current_ts = get_timestamp();
 571
 572         if (lowest_target_ts <= current_ts)
 573                 return 0;
 574
 575         return (lowest_target_ts - current_ts)/1000000; /* ms */
 576 }
 577
 578
 579 static void acknowledge_release (void)
 580 {
 581         /* A write to our socket circuit was performed to release epoll */
 582         char buf;
 583         read(poll_socket_pair[0], &buf, 1);
 584 }
 585
 586
 587 int sensor_poll(struct sensors_event_t* data, int count)
 588 {
 589         int s;
 590         int i;
 591         int nfds;
 592         int delta;
 593         struct epoll_event ev[MAX_DEVICES];
 594
 595         /* Get one or more events from our collection of sensors */
 596
 597 return_first_available_sensor_report:
 598
 599         /* If there's at least one available report */
 600         for (s=0; s<sensor_count; s++)
 601                 if (sensor_info[s].report_pending) {
 602
 603                         /* Return that up */
 604                         propagate_sensor_report(s, data);
 605                         sensor_info[s].report_pending = 0;
 606                         ALOGV("Report on sensor %d\n", s);
 607                         return 1;
 608                 }
 609 await_event:
 610
 611         /* Keep a minimum time interval between poll operations */
 612         delta = (get_timestamp() - last_poll_exit_ts)/1000;
 613
 614         if (delta > 0 && delta < POLL_MIN_INTERVAL)
 615                 usleep(POLL_MIN_INTERVAL - delta);
 616
 617         ALOGV("Awaiting sensor data\n");
 618
 619         nfds = epoll_wait(poll_fd, ev, MAX_DEVICES, get_poll_time());
 620
 621         last_poll_exit_ts = get_timestamp();
 622
 623         if (nfds == -1) {
 624                 ALOGI("epoll_wait returned -1 (%s)\n", strerror(errno));
 625                 goto await_event;
 626         }
 627
 628         ALOGV("%d fds signalled\n", nfds);
 629
 630         /* For each of the devices for which a report is available */
 631         for (i=0; i<nfds; i++)
 632                 if (ev[i].events == EPOLLIN) {
 633                         if (ev[i].data.u32 == INVALID_DEV_NUM) {
 634                                 acknowledge_release();
 635                                 goto await_event;
 636                         } else
 637                                 /* Read report */
 638                                 integrate_device_report(ev[i].data.u32);
 639                 }
 640
 641         /* It's a good time to invalidate poll-mode sensor values */
 642         if (active_poll_sensors)
 643                 for (s=0; s<sensor_count; s++)
 644                         if (sensor_info[s].enable_count &&
 645                                 !sensor_info[s].num_channels)
 646                                         sensor_info[s].report_pending = 1;
 647
 648         goto return_first_available_sensor_report;
 649 }
 650
 651
 652 int sensor_set_delay(int s, int64_t ns)
 653 {
 654         /* Set the rate at which a specific sensor should report events */
 655
 656         /* See Android sensors.h for indication on sensor trigger modes */
 657
 658         char sysfs_path[PATH_MAX];
 659         char avail_sysfs_path[PATH_MAX];
 660         int dev_num             =       sensor_info[s].dev_num;
 661         int i                   =       sensor_info[s].catalog_index;
 662         const char *prefix      =       sensor_catalog[i].tag;
 663         int new_sampling_rate;
 664         int cur_sampling_rate;
 665         int per_sensor_sampling_rate;
 666         int per_device_sampling_rate;
 667         char freqs_buf[100];
 668         char* cursor;
 669         int n;
 670
 671         if (!ns) {
 672                 ALOGE("Rejecting zero delay request on sensor %d\n", s);
 673                 return -EINVAL;
 674         }
 675
 676         sprintf(sysfs_path, SENSOR_SAMPLING_PATH, dev_num, prefix);
 677
 678         if (sysfs_read_int(sysfs_path, &cur_sampling_rate) != -1) {
 679                 per_sensor_sampling_rate = 1;
 680                 per_device_sampling_rate = 0;
 681         } else {
 682                 per_sensor_sampling_rate = 0;
 683
 684                 sprintf(sysfs_path, DEVICE_SAMPLING_PATH, dev_num);
 685
 686                 if (sysfs_read_int(sysfs_path, &cur_sampling_rate) != -1)
 687                         per_device_sampling_rate = 1;
 688                 else
 689                         per_device_sampling_rate = 0;
 690         }
 691
 692         if (!per_sensor_sampling_rate && !per_device_sampling_rate) {
 693                 ALOGE("No way to adjust sampling rate on sensor %d\n", s);
 694                 return -ENOSYS;
 695         }
 696
 697         new_sampling_rate = (int) (1000000000L/ns);
 698
 699         if (!new_sampling_rate) {
 700                 ALOGI("Sub-HZ sampling rate requested on on sensor %d\n", s);
 701                 new_sampling_rate = 1;
 702         }
 703
 704         sensor_info[s].sampling_rate = new_sampling_rate;
 705
 706         /* Coordinate with others active sensors on the same device, if any */
 707         if (per_device_sampling_rate)
 708                 for (n=0; n<sensor_count; n++)
 709                         if (n != s && sensor_info[n].dev_num == dev_num &&
 710                             sensor_info[n].enable_count &&
 711                             sensor_info[n].sampling_rate > new_sampling_rate)
 712                                 new_sampling_rate= sensor_info[n].sampling_rate;
 713
 714         /* Check if we have contraints on allowed sampling rates */
 715
 716         sprintf(avail_sysfs_path, DEVICE_AVAIL_FREQ_PATH, dev_num);
 717
 718         if (sysfs_read_str(avail_sysfs_path, freqs_buf, sizeof(freqs_buf)) > 0){
 719                 cursor = freqs_buf;
 720
 721                 /* Decode allowed sampling rates string, ex: "10 20 50 100" */
 722
 723                 /* While we're not at the end of the string */
 724                 while (*cursor && cursor[0]) {
 725
 726                         /* Decode a single integer value */
 727                         n = atoi(cursor);
 728
 729                         /* If this matches the selected rate, we're happy */
 730                         if (new_sampling_rate == n)
 731                                 break;
 732
 733                         /*
 734                          * If we reached a higher value than the desired rate,
 735                          * adjust selected rate so it matches the first higher
 736                          * available one and stop parsing - this makes the
 737                          * assumption that rates are sorted by increasing value
 738                          * in the allowed frequencies string.
 739                          */
 740                         if (n > new_sampling_rate) {
 741                                 ALOGI(
 742                                 "Increasing sampling rate on sensor %d to %d\n",
 743                                 s, n);
 744
 745                                 new_sampling_rate = n;
 746                                 break;
 747                         }
 748
 749                         /* Skip digits */
 750                         while (cursor[0] && !isspace(cursor[0]))
 751                                 cursor++;
 752
 753                         /* Skip spaces */
 754                         while (cursor[0] && isspace(cursor[0]))
 755                                         cursor++;
 756                 }
 757         }
 758
 759         /* If the desired rate is already active we're all set */
 760         if (new_sampling_rate == cur_sampling_rate)
 761                 return 0;
 762
 763         ALOGI("Sensor %d sampling rate set to %d\n", s, new_sampling_rate);
 764
 765         if (trig_sensors_per_dev[dev_num])
 766                 enable_buffer(dev_num, 0);
 767
 768         sysfs_write_int(sysfs_path, new_sampling_rate);
 769
 770         if (trig_sensors_per_dev[dev_num])
 771                 enable_buffer(dev_num, 1);
 772
 773         /* Release the polling loop so an updated timeout value gets used */
 774         write(poll_socket_pair[1], "", 1);
 775
 776         return 0;
 777 }
 778
 779
 780
 781 int allocate_control_data (void)
 782 {
 783         int i;
 784         struct epoll_event ev = {0};
 785
 786         for (i=0; i<MAX_DEVICES; i++)
 787                 device_fd[i] = -1;
 788
 789         poll_fd = epoll_create(MAX_DEVICES);
 790
 791         if (poll_fd == -1) {
 792                 ALOGE("Can't create epoll instance for iio sensors!\n");
 793                 return -1;
 794         }
 795
 796         /* Create and add "unblocking" fd to the set of watched fds */
 797
 798         if (socketpair(AF_UNIX, SOCK_STREAM, 0, poll_socket_pair) == -1) {
 799                 ALOGE("Can't create socket pair for iio sensors!\n");
 800                 close(poll_fd);
 801                 return -1;
 802         }
 803
 804         ev.events = EPOLLIN;
 805         ev.data.u32 = INVALID_DEV_NUM;
 806
 807         epoll_ctl(poll_fd, EPOLL_CTL_ADD, poll_socket_pair[0], &ev);
 808
 809         return poll_fd;
 810 }
 811
 812
 813 void delete_control_data (void)
 814 {
 815 }