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         } else {
 219                 if (sensor_info[s].enable_count == 0)
 220                         return -1; /* Spurious disable call */
 221
 222                 ALOGI("Disabling sensor %d (iio device %d: %s)\n", s, dev_num,
 223                       sensor_info[s].friendly_name);
 224
 225                 if (sensor_type == SENSOR_TYPE_MAGNETIC_FIELD)
 226                         compass_store_data(COMPASS_CALIBRATION_PATH);
 227
 228                 sensor_info[s].enable_count--;
 229
 230                 if (sensor_info[s].enable_count > 0)
 231                         return 0; /* The sensor was, and remains, in use */
 232
 233                 /* Sensor disabled, lower report available flag */
 234                 sensor_info[s].report_pending = 0;
 235         }
 236
 237         /* We changed the state of a sensor - adjust per iio device counters */
 238
 239         /* If this is a regular event-driven sensor */
 240         if (sensor_info[s].num_channels) {
 241
 242                         if (enabled)
 243                                 trig_sensors_per_dev[dev_num]++;
 244                         else
 245                                 trig_sensors_per_dev[dev_num]--;
 246
 247                         return 1;
 248                 }
 249
 250         if (enabled) {
 251                 active_poll_sensors++;
 252                 poll_sensors_per_dev[dev_num]++;
 253                 return 1;
 254         }
 255
 256         active_poll_sensors--;
 257         poll_sensors_per_dev[dev_num]--;
 258         return 1;
 259 }
 260
 261
 262 int sensor_activate(int s, int enabled)
 263 {
 264         char device_name[PATH_MAX];
 265         char trigger_name[MAX_NAME_SIZE + 16];
 266         int c;
 267         struct epoll_event ev = {0};
 268         int dev_fd;
 269         int ret;
 270         int dev_num = sensor_info[s].dev_num;
 271         int i = sensor_info[s].catalog_index;
 272         int is_poll_sensor = !sensor_info[s].num_channels;
 273
 274         ret = adjust_counters(s, enabled);
 275
 276         /* If the operation was neutral in terms of state, we're done */
 277         if (ret <= 0)
 278                 return ret;
 279
 280         if (!is_poll_sensor) {
 281
 282                 /* Stop sampling */
 283                 enable_buffer(dev_num, 0);
 284                 setup_trigger(dev_num, "\n");
 285
 286                 /* If there's at least one sensor enabled on this iio device */
 287                 if (trig_sensors_per_dev[dev_num]) {
 288                         sprintf(trigger_name, "%s-dev%d",
 289                                         sensor_info[s].internal_name, dev_num);
 290
 291                         /* Start sampling */
 292                         setup_trigger(dev_num, trigger_name);
 293                         enable_buffer(dev_num, 1);
 294                 }
 295         }
 296
 297         /*
 298          * Make sure we have a fd on the character device ; conversely, close
 299          * the fd if no one is using associated sensor anymore. The assumption
 300          * here is that the underlying driver will power on the relevant
 301          * hardware block while someone hold a fd on the device.
 302          */
 303         dev_fd = device_fd[dev_num];
 304
 305         if (!enabled) {
 306                 if (dev_fd != -1 && !poll_sensors_per_dev[dev_num] &&
 307                         !trig_sensors_per_dev[dev_num]) {
 308                                 /*
 309                                  * Stop watching this fd. This should be a no-op
 310                                  * in case this fd was not in the poll set.
 311                                  */
 312                                 epoll_ctl(poll_fd, EPOLL_CTL_DEL, dev_fd, NULL);
 313
 314                                 close(dev_fd);
 315                                 device_fd[dev_num] = -1;
 316                         }
 317                 return 0;
 318         }
 319
 320         if (dev_fd == -1) {
 321                 /* First enabled sensor on this iio device */
 322                 sprintf(device_name, DEV_FILE_PATH, dev_num);
 323                 dev_fd = open(device_name, O_RDONLY | O_NONBLOCK);
 324
 325                 device_fd[dev_num] = dev_fd;
 326
 327                 if (dev_fd == -1) {
 328                         ALOGE("Could not open fd on %s (%s)\n",
 329                               device_name, strerror(errno));
 330                         adjust_counters(s, 0);
 331                         return -1;
 332                 }
 333
 334                 ALOGV("Opened %s: fd=%d\n", device_name, dev_fd);
 335
 336                 if (!is_poll_sensor) {
 337
 338                         /* Add this iio device fd to the set of watched fds */
 339                         ev.events = EPOLLIN;
 340                         ev.data.u32 = dev_num;
 341
 342                         ret = epoll_ctl(poll_fd, EPOLL_CTL_ADD, dev_fd, &ev);
 343
 344                         if (ret == -1) {
 345                                 ALOGE(  "Failed adding %d to poll set (%s)\n",
 346                                         dev_fd, strerror(errno));
 347                                 return -1;
 348                         }
 349
 350                         /* Note: poll-mode fds are not readable */
 351                 }
 352         }
 353
 354         /* Release the polling loop so an updated timeout gets used */
 355         write(poll_socket_pair[1], "", 1);
 356
 357         return 0;
 358 }
 359
 360
 361 static int integrate_device_report(int dev_num)
 362 {
 363         int len;
 364         int s,c;
 365         unsigned char buf[MAX_SENSOR_REPORT_SIZE * MAX_SENSORS] = { 0 };
 366         int sr_offset;
 367         unsigned char *target;
 368         unsigned char *source;
 369         int size;
 370         int expected_size = 0;
 371         int ts;
 372
 373         /* There's an incoming report on the specified fd */
 374
 375         if (dev_num < 0 || dev_num >= MAX_DEVICES) {
 376                 ALOGE("Event reported on unexpected iio device %d\n", dev_num);
 377                 return -1;
 378         }
 379
 380         if (device_fd[dev_num] == -1) {
 381                 ALOGE("Ignoring stale report on iio device %d\n", dev_num);
 382                 return -1;
 383         }
 384
 385         for (s=0; s<MAX_SENSORS; s++)
 386                 if (sensor_info[s].dev_num == dev_num)
 387                         for (c=0; c<sensor_info[s].num_channels; c++)
 388                                 expected_size += sensor_info[s].channel[c].size;
 389
 390         ts = get_timestamp();
 391
 392         len = read(device_fd[dev_num], buf, expected_size);
 393
 394         if (len == -1) {
 395                 ALOGE("Could not read report from iio device %d (%s)\n",
 396                       dev_num, strerror(errno));
 397                 return -1;
 398         }
 399
 400         ALOGV("Read %d bytes from iio device %d\n", len, dev_num);
 401
 402         for (s=0; s<MAX_SENSORS; s++)
 403                 if (sensor_info[s].dev_num == dev_num &&
 404                     sensor_info[s].enable_count) {
 405
 406                         sr_offset = 0;
 407
 408                         /* Copy data from device to sensor report buffer */
 409                         for (c=0; c<sensor_info[s].num_channels; c++) {
 410
 411                                 target = sensor_info[s].report_buffer +
 412                                         sr_offset;
 413
 414                                 source = buf + sensor_info[s].channel[c].offset;
 415
 416                                 size = sensor_info[s].channel[c].size;
 417
 418                                 memcpy(target, source, size);
 419
 420                                 sr_offset += size;
 421                         }
 422
 423                         ALOGV("Sensor %d report available (%d bytes)\n", s,
 424                               sr_offset);
 425
 426                         sensor_info[s].report_ts = ts;
 427                         sensor_info[s].report_pending = 1;
 428                 }
 429
 430         return 0;
 431 }
 432
 433
 434 static void propagate_sensor_report(int s, struct sensors_event_t* data)
 435 {
 436         /* There's a sensor report pending for this sensor ; transmit it */
 437
 438         int catalog_index = sensor_info[s].catalog_index;
 439         int sensor_type = sensor_catalog[catalog_index].type;
 440         int num_fields;
 441         int c;
 442         unsigned char* current_sample;
 443         int64_t current_ts = get_timestamp();
 444
 445         memset(data, 0, sizeof(sensors_event_t));
 446
 447         data->version = sizeof(sensors_event_t);
 448         data->sensor = s;
 449         data->type = sensor_type;
 450
 451         if (sensor_info[s].report_ts)
 452                 data->timestamp = sensor_info[s].report_ts;
 453         else
 454                 data->timestamp = current_ts;
 455
 456         switch (sensor_type) {
 457                 case SENSOR_TYPE_ACCELEROMETER:         /* m/s^2        */
 458                 case SENSOR_TYPE_MAGNETIC_FIELD:        /* micro-tesla  */
 459                 case SENSOR_TYPE_ORIENTATION:           /* degrees      */
 460                 case SENSOR_TYPE_GYROSCOPE:             /* radians/s    */
 461                         num_fields = 3;
 462                         break;
 463
 464                 case SENSOR_TYPE_LIGHT:                 /* SI lux units */
 465                 case SENSOR_TYPE_AMBIENT_TEMPERATURE:   /* °C          */
 466                 case SENSOR_TYPE_TEMPERATURE:           /* °C          */
 467                 case SENSOR_TYPE_PROXIMITY:             /* centimeters  */
 468                 case SENSOR_TYPE_PRESSURE:              /* hecto-pascal */
 469                 case SENSOR_TYPE_RELATIVE_HUMIDITY:     /* percent */
 470                         num_fields = 1;
 471                         break;
 472
 473                 case SENSOR_TYPE_ROTATION_VECTOR:
 474                         num_fields = 4;
 475                         break;
 476
 477                 case SENSOR_TYPE_DEVICE_PRIVATE_BASE:   /* hidden for now */
 478                         num_fields = 0;
 479                         break;
 480
 481                 default:
 482                         ALOGE("Unknown sensor type!\n");
 483                         num_fields = 0;
 484                         break;
 485         }
 486
 487         ALOGV("Sample on sensor %d (type %d):\n", s, sensor_type);
 488
 489         /* Take note of current time counter value for rate control purposes */
 490         sensor_info[s].last_integration_ts = current_ts;
 491
 492         /* If we're dealing with a poll-mode sensor */
 493         if (!sensor_info[s].num_channels) {
 494
 495                 /* Read values through sysfs rather than from a report buffer */
 496                 for (c=0; c<num_fields; c++) {
 497
 498                         data->data[c] = acquire_immediate_value(s, c);
 499
 500                         ALOGV("\tfield %d: %f\n", c, data->data[c]);
 501                 }
 502
 503                 sensor_info[s].ops.finalize(s, data);
 504                 return;
 505         }
 506
 507         /* Convert the data into the expected Android-level format */
 508
 509         current_sample = sensor_info[s].report_buffer;
 510
 511         for (c=0; c<num_fields; c++) {
 512
 513                 data->data[c] = sensor_info[s].ops.transform
 514                                                         (s, c, current_sample);
 515
 516                 ALOGV("\tfield %d: %f\n", c, data->data[c]);
 517                 current_sample += sensor_info[s].channel[c].size;
 518         }
 519
 520         sensor_info[s].ops.finalize(s, data);
 521 }
 522
 523
 524 static int get_poll_time (void)
 525 {
 526         int64_t target_ts;
 527         int64_t lowest_target_ts;
 528         int64_t current_ts;
 529         int s;
 530
 531         if (!active_poll_sensors)
 532                 return -1;      /* Infinite wait */
 533
 534         /* Check if we should schedule a poll-mode sensor event delivery */
 535
 536         lowest_target_ts = INT64_MAX;
 537
 538         for (s=0; s<sensor_count; s++)
 539                 if (sensor_info[s].enable_count &&
 540                     sensor_info[s].sampling_rate &&
 541                     !sensor_info[s].num_channels) {
 542                                 target_ts = sensor_info[s].last_integration_ts +
 543                                       1000000000LL/sensor_info[s].sampling_rate;
 544
 545                                 if (target_ts < lowest_target_ts)
 546                                         lowest_target_ts = target_ts;
 547                         }
 548
 549         if (lowest_target_ts == INT64_MAX)
 550                 return -1;
 551
 552         current_ts = get_timestamp();
 553
 554         if (lowest_target_ts <= current_ts)
 555                 return 0;
 556
 557         return (lowest_target_ts - current_ts)/1000000; /* ms */
 558 }
 559
 560
 561 static void acknowledge_release (void)
 562 {
 563         /* A write to our socket circuit was performed to release epoll */
 564         char buf;
 565         read(poll_socket_pair[0], &buf, 1);
 566 }
 567
 568
 569 int sensor_poll(struct sensors_event_t* data, int count)
 570 {
 571         int s;
 572         int i;
 573         int nfds;
 574         int delta;
 575         struct epoll_event ev[MAX_DEVICES];
 576         int64_t target_ts;
 577
 578         /* Get one or more events from our collection of sensors */
 579
 580 return_first_available_sensor_report:
 581
 582         /* If there's at least one available report */
 583         for (s=0; s<sensor_count; s++)
 584                 if (sensor_info[s].report_pending) {
 585
 586                         /* Return that up */
 587                         propagate_sensor_report(s, data);
 588                         sensor_info[s].report_pending = 0;
 589                         ALOGV("Report on sensor %d\n", s);
 590                         return 1;
 591                 }
 592 await_event:
 593
 594         ALOGV("Awaiting sensor data\n");
 595
 596         nfds = epoll_wait(poll_fd, ev, MAX_DEVICES, get_poll_time());
 597
 598         last_poll_exit_ts = get_timestamp();
 599
 600         if (nfds == -1) {
 601                 ALOGI("epoll_wait returned -1 (%s)\n", strerror(errno));
 602                 goto await_event;
 603         }
 604
 605         ALOGV("%d fds signalled\n", nfds);
 606
 607         /* For each of the devices for which a report is available */
 608         for (i=0; i<nfds; i++)
 609                 if (ev[i].events == EPOLLIN) {
 610                         if (ev[i].data.u32 == INVALID_DEV_NUM) {
 611                                 acknowledge_release();
 612                                 goto await_event;
 613                         } else
 614                                 /* Read report */
 615                                 integrate_device_report(ev[i].data.u32);
 616                 }
 617
 618         /* Check poll-mode sensors and fire up an event if it's time to do so */
 619         if (active_poll_sensors)
 620                 for (s=0; s<sensor_count; s++)
 621                         if (sensor_info[s].enable_count &&
 622                             !sensor_info[s].num_channels &&
 623                             sensor_info[s].sampling_rate) {
 624                                 target_ts = sensor_info[s].last_integration_ts +
 625                                       1000000000LL/sensor_info[s].sampling_rate;
 626
 627                                 if (last_poll_exit_ts >= target_ts)
 628                                         sensor_info[s].report_pending = 1;
 629                         }
 630
 631         goto return_first_available_sensor_report;
 632 }
 633
 634
 635 int sensor_set_delay(int s, int64_t ns)
 636 {
 637         /* Set the rate at which a specific sensor should report events */
 638
 639         /* See Android sensors.h for indication on sensor trigger modes */
 640
 641         char sysfs_path[PATH_MAX];
 642         char avail_sysfs_path[PATH_MAX];
 643         int dev_num             =       sensor_info[s].dev_num;
 644         int i                   =       sensor_info[s].catalog_index;
 645         const char *prefix      =       sensor_catalog[i].tag;
 646         int new_sampling_rate;  /* Granted sampling rate after arbitration   */
 647         int cur_sampling_rate;  /* Currently used sampling rate              */
 648         int req_sampling_rate;  /* Requested ; may be different from granted */
 649         int per_sensor_sampling_rate;
 650         int per_device_sampling_rate;
 651         int max_supported_rate = 0;
 652         int limit;
 653         char freqs_buf[100];
 654         char* cursor;
 655         int n;
 656
 657         if (!ns) {
 658                 ALOGE("Rejecting zero delay request on sensor %d\n", s);
 659                 return -EINVAL;
 660         }
 661
 662         new_sampling_rate = req_sampling_rate = (int) (1000000000L/ns);
 663
 664         if (!new_sampling_rate) {
 665                 ALOGI("Sub-HZ sampling rate requested on on sensor %d\n", s);
 666                 new_sampling_rate = 1;
 667         }
 668
 669         sensor_info[s].sampling_rate = new_sampling_rate;
 670
 671         /* If we're dealing with a poll-mode sensor, release poll and return */
 672         if (!sensor_info[s].num_channels)
 673                 goto exit;
 674
 675         sprintf(sysfs_path, SENSOR_SAMPLING_PATH, dev_num, prefix);
 676
 677         if (sysfs_read_int(sysfs_path, &cur_sampling_rate) != -1) {
 678                 per_sensor_sampling_rate = 1;
 679                 per_device_sampling_rate = 0;
 680         } else {
 681                 per_sensor_sampling_rate = 0;
 682
 683                 sprintf(sysfs_path, DEVICE_SAMPLING_PATH, dev_num);
 684
 685                 if (sysfs_read_int(sysfs_path, &cur_sampling_rate) != -1)
 686                         per_device_sampling_rate = 1;
 687                 else
 688                         per_device_sampling_rate = 0;
 689         }
 690
 691         if (!per_sensor_sampling_rate && !per_device_sampling_rate) {
 692                 ALOGE("No way to adjust sampling rate on sensor %d\n", s);
 693                 return -ENOSYS;
 694         }
 695
 696         /* Coordinate with others active sensors on the same device, if any */
 697         if (per_device_sampling_rate)
 698                 for (n=0; n<sensor_count; n++)
 699                         if (n != s && sensor_info[n].dev_num == dev_num &&
 700                             sensor_info[n].num_channels &&
 701                             sensor_info[n].enable_count &&
 702                             sensor_info[n].sampling_rate > new_sampling_rate)
 703                                 new_sampling_rate= sensor_info[n].sampling_rate;
 704
 705         /* Check if we have contraints on allowed sampling rates */
 706
 707         sprintf(avail_sysfs_path, DEVICE_AVAIL_FREQ_PATH, dev_num);
 708
 709         if (sysfs_read_str(avail_sysfs_path, freqs_buf, sizeof(freqs_buf)) > 0){
 710                 cursor = freqs_buf;
 711
 712                 /* Decode allowed sampling rates string, ex: "10 20 50 100" */
 713
 714                 /* While we're not at the end of the string */
 715                 while (*cursor && cursor[0]) {
 716
 717                         /* Decode a single integer value */
 718                         n = atoi(cursor);
 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         /* Cap sampling rate at 1000 events per second for now*/
 754
 755         limit = 1000;
 756
 757         if (max_supported_rate && new_sampling_rate > max_supported_rate)
 758                 limit = max_supported_rate;
 759
 760         if (new_sampling_rate > limit) {
 761
 762                 new_sampling_rate = limit;
 763
 764                 ALOGI(  "Can't support %d sampling rate, lowering to %d\n",
 765                         req_sampling_rate, new_sampling_rate);
 766         }
 767
 768         /* If the desired rate is already active we're all set */
 769         if (new_sampling_rate == cur_sampling_rate)
 770                 return 0;
 771
 772         ALOGI("Sensor %d sampling rate switched to %d\n", s, new_sampling_rate);
 773
 774         if (trig_sensors_per_dev[dev_num])
 775                 enable_buffer(dev_num, 0);
 776
 777         sysfs_write_int(sysfs_path, new_sampling_rate);
 778
 779         if (trig_sensors_per_dev[dev_num])
 780                 enable_buffer(dev_num, 1);
 781
 782 exit:
 783         /* Release the polling loop so an updated timeout value gets used */
 784         write(poll_socket_pair[1], "", 1);
 785
 786         return 0;
 787 }
 788
 789
 790
 791 int allocate_control_data (void)
 792 {
 793         int i;
 794         struct epoll_event ev = {0};
 795
 796         for (i=0; i<MAX_DEVICES; i++)
 797                 device_fd[i] = -1;
 798
 799         poll_fd = epoll_create(MAX_DEVICES);
 800
 801         if (poll_fd == -1) {
 802                 ALOGE("Can't create epoll instance for iio sensors!\n");
 803                 return -1;
 804         }
 805
 806         /* Create and add "unblocking" fd to the set of watched fds */
 807
 808         if (socketpair(AF_UNIX, SOCK_STREAM, 0, poll_socket_pair) == -1) {
 809                 ALOGE("Can't create socket pair for iio sensors!\n");
 810                 close(poll_fd);
 811                 return -1;
 812         }
 813
 814         ev.events = EPOLLIN;
 815         ev.data.u32 = INVALID_DEV_NUM;
 816
 817         epoll_ctl(poll_fd, EPOLL_CTL_ADD, poll_socket_pair[0], &ev);
 818
 819         return poll_fd;
 820 }
 821
 822
 823 void delete_control_data (void)
 824 {
 825 }