drivers/iio/adc/ad_sigma_delta.c

   1 /*
   2  * Support code for Analog Devices Sigma-Delta ADCs
   3  *
   4  * Copyright 2012 Analog Devices Inc.
   5  *  Author: Lars-Peter Clausen <lars@metafoo.de>
   6  *
   7  * Licensed under the GPL-2.
   8  */
   9
  10 #include <linux/interrupt.h>
  11 #include <linux/device.h>
  12 #include <linux/kernel.h>
  13 #include <linux/slab.h>
  14 #include <linux/spi/spi.h>
  15 #include <linux/err.h>
  16 #include <linux/module.h>
  17
  18 #include <linux/iio/iio.h>
  19 #include <linux/iio/sysfs.h>
  20 #include <linux/iio/buffer.h>
  21 #include <linux/iio/trigger.h>
  22 #include <linux/iio/trigger_consumer.h>
  23 #include <linux/iio/triggered_buffer.h>
  24 #include <linux/iio/adc/ad_sigma_delta.h>
  25
  26 #include <asm/unaligned.h>
  27
  28
  29 #define AD_SD_COMM_CHAN_MASK    0x3
  30
  31 #define AD_SD_REG_COMM          0x00
  32 #define AD_SD_REG_DATA          0x03
  33
  34 /**
  35  * ad_sd_set_comm() - Set communications register
  36  *
  37  * @sigma_delta: The sigma delta device
  38  * @comm: New value for the communications register
  39  */
  40 void ad_sd_set_comm(struct ad_sigma_delta *sigma_delta, uint8_t comm)
  41 {
  42         /* Some variants use the lower two bits of the communications register
  43          * to select the channel */
  44         sigma_delta->comm = comm & AD_SD_COMM_CHAN_MASK;
  45 }
  46 EXPORT_SYMBOL_GPL(ad_sd_set_comm);
  47
  48 /**
  49  * ad_sd_write_reg() - Write a register
  50  *
  51  * @sigma_delta: The sigma delta device
  52  * @reg: Address of the register
  53  * @size: Size of the register (0-3)
  54  * @val: Value to write to the register
  55  *
  56  * Returns 0 on success, an error code otherwise.
  57  **/
  58 int ad_sd_write_reg(struct ad_sigma_delta *sigma_delta, unsigned int reg,
  59         unsigned int size, unsigned int val)
  60 {
  61         uint8_t *data = sigma_delta->data;
  62         struct spi_transfer t = {
  63                 .tx_buf         = data,
  64                 .len            = size + 1,
  65                 .cs_change      = sigma_delta->keep_cs_asserted,
  66         };
  67         struct spi_message m;
  68         int ret;
  69
  70         data[0] = (reg << sigma_delta->info->addr_shift) | sigma_delta->comm;
  71
  72         switch (size) {
  73         case 3:
  74                 data[1] = val >> 16;
  75                 data[2] = val >> 8;
  76                 data[3] = val;
  77                 break;
  78         case 2:
  79                 put_unaligned_be16(val, &data[1]);
  80                 break;
  81         case 1:
  82                 data[1] = val;
  83                 break;
  84         case 0:
  85                 break;
  86         default:
  87                 return -EINVAL;
  88         }
  89
  90         spi_message_init(&m);
  91         spi_message_add_tail(&t, &m);
  92
  93         if (sigma_delta->bus_locked)
  94                 ret = spi_sync_locked(sigma_delta->spi, &m);
  95         else
  96                 ret = spi_sync(sigma_delta->spi, &m);
  97
  98         return ret;
  99 }
 100 EXPORT_SYMBOL_GPL(ad_sd_write_reg);
 101
 102 static int ad_sd_read_reg_raw(struct ad_sigma_delta *sigma_delta,
 103         unsigned int reg, unsigned int size, uint8_t *val)
 104 {
 105         uint8_t *data = sigma_delta->data;
 106         int ret;
 107         struct spi_transfer t[] = {
 108                 {
 109                         .tx_buf = data,
 110                         .len = 1,
 111                 }, {
 112                         .rx_buf = val,
 113                         .len = size,
 114                         .cs_change = sigma_delta->bus_locked,
 115                 },
 116         };
 117         struct spi_message m;
 118
 119         spi_message_init(&m);
 120
 121         if (sigma_delta->info->has_registers) {
 122                 data[0] = reg << sigma_delta->info->addr_shift;
 123                 data[0] |= sigma_delta->info->read_mask;
 124                 data[0] |= sigma_delta->comm;
 125                 spi_message_add_tail(&t[0], &m);
 126         }
 127         spi_message_add_tail(&t[1], &m);
 128
 129         if (sigma_delta->bus_locked)
 130                 ret = spi_sync_locked(sigma_delta->spi, &m);
 131         else
 132                 ret = spi_sync(sigma_delta->spi, &m);
 133
 134         return ret;
 135 }
 136
 137 /**
 138  * ad_sd_read_reg() - Read a register
 139  *
 140  * @sigma_delta: The sigma delta device
 141  * @reg: Address of the register
 142  * @size: Size of the register (1-4)
 143  * @val: Read value
 144  *
 145  * Returns 0 on success, an error code otherwise.
 146  **/
 147 int ad_sd_read_reg(struct ad_sigma_delta *sigma_delta,
 148         unsigned int reg, unsigned int size, unsigned int *val)
 149 {
 150         int ret;
 151
 152         ret = ad_sd_read_reg_raw(sigma_delta, reg, size, sigma_delta->data);
 153         if (ret < 0)
 154                 goto out;
 155
 156         switch (size) {
 157         case 4:
 158                 *val = get_unaligned_be32(sigma_delta->data);
 159                 break;
 160         case 3:
 161                 *val = (sigma_delta->data[0] << 16) |
 162                         (sigma_delta->data[1] << 8) |
 163                         sigma_delta->data[2];
 164                 break;
 165         case 2:
 166                 *val = get_unaligned_be16(sigma_delta->data);
 167                 break;
 168         case 1:
 169                 *val = sigma_delta->data[0];
 170                 break;
 171         default:
 172                 ret = -EINVAL;
 173                 break;
 174         }
 175
 176 out:
 177         return ret;
 178 }
 179 EXPORT_SYMBOL_GPL(ad_sd_read_reg);
 180
 181 /**
 182  * ad_sd_reset() - Reset the serial interface
 183  *
 184  * @sigma_delta: The sigma delta device
 185  * @reset_length: Number of SCLKs with DIN = 1
 186  *
 187  * Returns 0 on success, an error code otherwise.
 188  **/
 189 int ad_sd_reset(struct ad_sigma_delta *sigma_delta,
 190         unsigned int reset_length)
 191 {
 192         uint8_t *buf;
 193         unsigned int size;
 194         int ret;
 195
 196         size = DIV_ROUND_UP(reset_length, 8);
 197         buf = kcalloc(size, sizeof(*buf), GFP_KERNEL);
 198         if (!buf)
 199                 return -ENOMEM;
 200
 201         memset(buf, 0xff, size);
 202         ret = spi_write(sigma_delta->spi, buf, size);
 203         kfree(buf);
 204
 205         return ret;
 206 }
 207 EXPORT_SYMBOL_GPL(ad_sd_reset);
 208
 209 static int ad_sd_calibrate(struct ad_sigma_delta *sigma_delta,
 210         unsigned int mode, unsigned int channel)
 211 {
 212         int ret;
 213
 214         ret = ad_sigma_delta_set_channel(sigma_delta, channel);
 215         if (ret)
 216                 return ret;
 217
 218         spi_bus_lock(sigma_delta->spi->master);
 219         sigma_delta->bus_locked = true;
 220         sigma_delta->keep_cs_asserted = true;
 221         reinit_completion(&sigma_delta->completion);
 222
 223         ret = ad_sigma_delta_set_mode(sigma_delta, mode);
 224         if (ret < 0)
 225                 goto out;
 226
 227         sigma_delta->irq_dis = false;
 228         enable_irq(sigma_delta->spi->irq);
 229         ret = wait_for_completion_timeout(&sigma_delta->completion, 2*HZ);
 230         if (ret == 0) {
 231                 sigma_delta->irq_dis = true;
 232                 disable_irq_nosync(sigma_delta->spi->irq);
 233                 ret = -EIO;
 234         } else {
 235                 ret = 0;
 236         }
 237 out:
 238         sigma_delta->keep_cs_asserted = false;
 239         ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_IDLE);
 240         sigma_delta->bus_locked = false;
 241         spi_bus_unlock(sigma_delta->spi->master);
 242
 243         return ret;
 244 }
 245
 246 /**
 247  * ad_sd_calibrate_all() - Performs channel calibration
 248  * @sigma_delta: The sigma delta device
 249  * @cb: Array of channels and calibration type to perform
 250  * @n: Number of items in cb
 251  *
 252  * Returns 0 on success, an error code otherwise.
 253  **/
 254 int ad_sd_calibrate_all(struct ad_sigma_delta *sigma_delta,
 255         const struct ad_sd_calib_data *cb, unsigned int n)
 256 {
 257         unsigned int i;
 258         int ret;
 259
 260         for (i = 0; i < n; i++) {
 261                 ret = ad_sd_calibrate(sigma_delta, cb[i].mode, cb[i].channel);
 262                 if (ret)
 263                         return ret;
 264         }
 265
 266         return 0;
 267 }
 268 EXPORT_SYMBOL_GPL(ad_sd_calibrate_all);
 269
 270 /**
 271  * ad_sigma_delta_single_conversion() - Performs a single data conversion
 272  * @indio_dev: The IIO device
 273  * @chan: The conversion is done for this channel
 274  * @val: Pointer to the location where to store the read value
 275  *
 276  * Returns: 0 on success, an error value otherwise.
 277  */
 278 int ad_sigma_delta_single_conversion(struct iio_dev *indio_dev,
 279         const struct iio_chan_spec *chan, int *val)
 280 {
 281         struct ad_sigma_delta *sigma_delta = iio_device_get_drvdata(indio_dev);
 282         unsigned int sample, raw_sample;
 283         int ret = 0;
 284
 285         if (iio_buffer_enabled(indio_dev))
 286                 return -EBUSY;
 287
 288         mutex_lock(&indio_dev->mlock);
 289         ad_sigma_delta_set_channel(sigma_delta, chan->address);
 290
 291         spi_bus_lock(sigma_delta->spi->master);
 292         sigma_delta->bus_locked = true;
 293         sigma_delta->keep_cs_asserted = true;
 294         reinit_completion(&sigma_delta->completion);
 295
 296         ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_SINGLE);
 297
 298         sigma_delta->irq_dis = false;
 299         enable_irq(sigma_delta->spi->irq);
 300         ret = wait_for_completion_interruptible_timeout(
 301                         &sigma_delta->completion, HZ);
 302
 303         if (ret == 0)
 304                 ret = -EIO;
 305         if (ret < 0)
 306                 goto out;
 307
 308         ret = ad_sd_read_reg(sigma_delta, AD_SD_REG_DATA,
 309                 DIV_ROUND_UP(chan->scan_type.realbits + chan->scan_type.shift, 8),
 310                 &raw_sample);
 311
 312 out:
 313         if (!sigma_delta->irq_dis) {
 314                 disable_irq_nosync(sigma_delta->spi->irq);
 315                 sigma_delta->irq_dis = true;
 316         }
 317
 318         sigma_delta->keep_cs_asserted = false;
 319         ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_IDLE);
 320         sigma_delta->bus_locked = false;
 321         spi_bus_unlock(sigma_delta->spi->master);
 322         mutex_unlock(&indio_dev->mlock);
 323
 324         if (ret)
 325                 return ret;
 326
 327         sample = raw_sample >> chan->scan_type.shift;
 328         sample &= (1 << chan->scan_type.realbits) - 1;
 329         *val = sample;
 330
 331         ret = ad_sigma_delta_postprocess_sample(sigma_delta, raw_sample);
 332         if (ret)
 333                 return ret;
 334
 335         return IIO_VAL_INT;
 336 }
 337 EXPORT_SYMBOL_GPL(ad_sigma_delta_single_conversion);
 338
 339 static int ad_sd_buffer_postenable(struct iio_dev *indio_dev)
 340 {
 341         struct ad_sigma_delta *sigma_delta = iio_device_get_drvdata(indio_dev);
 342         unsigned int channel;
 343         int ret;
 344
 345         ret = iio_triggered_buffer_postenable(indio_dev);
 346         if (ret < 0)
 347                 return ret;
 348
 349         channel = find_first_bit(indio_dev->active_scan_mask,
 350                                  indio_dev->masklength);
 351         ret = ad_sigma_delta_set_channel(sigma_delta,
 352                 indio_dev->channels[channel].address);
 353         if (ret)
 354                 goto err_predisable;
 355
 356         spi_bus_lock(sigma_delta->spi->master);
 357         sigma_delta->bus_locked = true;
 358         sigma_delta->keep_cs_asserted = true;
 359
 360         ret = ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_CONTINUOUS);
 361         if (ret)
 362                 goto err_unlock;
 363
 364         sigma_delta->irq_dis = false;
 365         enable_irq(sigma_delta->spi->irq);
 366
 367         return 0;
 368
 369 err_unlock:
 370         spi_bus_unlock(sigma_delta->spi->master);
 371 err_predisable:
 372
 373         return ret;
 374 }
 375
 376 static int ad_sd_buffer_postdisable(struct iio_dev *indio_dev)
 377 {
 378         struct ad_sigma_delta *sigma_delta = iio_device_get_drvdata(indio_dev);
 379
 380         reinit_completion(&sigma_delta->completion);
 381         wait_for_completion_timeout(&sigma_delta->completion, HZ);
 382
 383         if (!sigma_delta->irq_dis) {
 384                 disable_irq_nosync(sigma_delta->spi->irq);
 385                 sigma_delta->irq_dis = true;
 386         }
 387
 388         sigma_delta->keep_cs_asserted = false;
 389         ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_IDLE);
 390
 391         sigma_delta->bus_locked = false;
 392         return spi_bus_unlock(sigma_delta->spi->master);
 393 }
 394
 395 static irqreturn_t ad_sd_trigger_handler(int irq, void *p)
 396 {
 397         struct iio_poll_func *pf = p;
 398         struct iio_dev *indio_dev = pf->indio_dev;
 399         struct ad_sigma_delta *sigma_delta = iio_device_get_drvdata(indio_dev);
 400         unsigned int reg_size;
 401         uint8_t data[16];
 402         int ret;
 403
 404         memset(data, 0x00, 16);
 405
 406         reg_size = indio_dev->channels[0].scan_type.realbits +
 407                         indio_dev->channels[0].scan_type.shift;
 408         reg_size = DIV_ROUND_UP(reg_size, 8);
 409
 410         switch (reg_size) {
 411         case 4:
 412         case 2:
 413         case 1:
 414                 ret = ad_sd_read_reg_raw(sigma_delta, AD_SD_REG_DATA,
 415                         reg_size, &data[0]);
 416                 break;
 417         case 3:
 418                 /* We store 24 bit samples in a 32 bit word. Keep the upper
 419                  * byte set to zero. */
 420                 ret = ad_sd_read_reg_raw(sigma_delta, AD_SD_REG_DATA,
 421                         reg_size, &data[1]);
 422                 break;
 423         }
 424
 425         iio_push_to_buffers_with_timestamp(indio_dev, data, pf->timestamp);
 426
 427         iio_trigger_notify_done(indio_dev->trig);
 428         sigma_delta->irq_dis = false;
 429         enable_irq(sigma_delta->spi->irq);
 430
 431         return IRQ_HANDLED;
 432 }
 433
 434 static const struct iio_buffer_setup_ops ad_sd_buffer_setup_ops = {
 435         .postenable = &ad_sd_buffer_postenable,
 436         .predisable = &iio_triggered_buffer_predisable,
 437         .postdisable = &ad_sd_buffer_postdisable,
 438         .validate_scan_mask = &iio_validate_scan_mask_onehot,
 439 };
 440
 441 static irqreturn_t ad_sd_data_rdy_trig_poll(int irq, void *private)
 442 {
 443         struct ad_sigma_delta *sigma_delta = private;
 444
 445         complete(&sigma_delta->completion);
 446         disable_irq_nosync(irq);
 447         sigma_delta->irq_dis = true;
 448         iio_trigger_poll(sigma_delta->trig);
 449
 450         return IRQ_HANDLED;
 451 }
 452
 453 /**
 454  * ad_sd_validate_trigger() - validate_trigger callback for ad_sigma_delta devices
 455  * @indio_dev: The IIO device
 456  * @trig: The new trigger
 457  *
 458  * Returns: 0 if the 'trig' matches the trigger registered by the ad_sigma_delta
 459  * device, -EINVAL otherwise.
 460  */
 461 int ad_sd_validate_trigger(struct iio_dev *indio_dev, struct iio_trigger *trig)
 462 {
 463         struct ad_sigma_delta *sigma_delta = iio_device_get_drvdata(indio_dev);
 464
 465         if (sigma_delta->trig != trig)
 466                 return -EINVAL;
 467
 468         return 0;
 469 }
 470 EXPORT_SYMBOL_GPL(ad_sd_validate_trigger);
 471
 472 static const struct iio_trigger_ops ad_sd_trigger_ops = {
 473         .owner = THIS_MODULE,
 474 };
 475
 476 static int ad_sd_probe_trigger(struct iio_dev *indio_dev)
 477 {
 478         struct ad_sigma_delta *sigma_delta = iio_device_get_drvdata(indio_dev);
 479         int ret;
 480
 481         sigma_delta->trig = iio_trigger_alloc("%s-dev%d", indio_dev->name,
 482                                                 indio_dev->id);
 483         if (sigma_delta->trig == NULL) {
 484                 ret = -ENOMEM;
 485                 goto error_ret;
 486         }
 487         sigma_delta->trig->ops = &ad_sd_trigger_ops;
 488         init_completion(&sigma_delta->completion);
 489
 490         ret = request_irq(sigma_delta->spi->irq,
 491                           ad_sd_data_rdy_trig_poll,
 492                           IRQF_TRIGGER_LOW,
 493                           indio_dev->name,
 494                           sigma_delta);
 495         if (ret)
 496                 goto error_free_trig;
 497
 498         if (!sigma_delta->irq_dis) {
 499                 sigma_delta->irq_dis = true;
 500                 disable_irq_nosync(sigma_delta->spi->irq);
 501         }
 502         sigma_delta->trig->dev.parent = &sigma_delta->spi->dev;
 503         iio_trigger_set_drvdata(sigma_delta->trig, sigma_delta);
 504
 505         ret = iio_trigger_register(sigma_delta->trig);
 506         if (ret)
 507                 goto error_free_irq;
 508
 509         /* select default trigger */
 510         indio_dev->trig = iio_trigger_get(sigma_delta->trig);
 511
 512         return 0;
 513
 514 error_free_irq:
 515         free_irq(sigma_delta->spi->irq, sigma_delta);
 516 error_free_trig:
 517         iio_trigger_free(sigma_delta->trig);
 518 error_ret:
 519         return ret;
 520 }
 521
 522 static void ad_sd_remove_trigger(struct iio_dev *indio_dev)
 523 {
 524         struct ad_sigma_delta *sigma_delta = iio_device_get_drvdata(indio_dev);
 525
 526         iio_trigger_unregister(sigma_delta->trig);
 527         free_irq(sigma_delta->spi->irq, sigma_delta);
 528         iio_trigger_free(sigma_delta->trig);
 529 }
 530
 531 /**
 532  * ad_sd_setup_buffer_and_trigger() -
 533  * @indio_dev: The IIO device
 534  */
 535 int ad_sd_setup_buffer_and_trigger(struct iio_dev *indio_dev)
 536 {
 537         int ret;
 538
 539         ret = iio_triggered_buffer_setup(indio_dev, &iio_pollfunc_store_time,
 540                         &ad_sd_trigger_handler, &ad_sd_buffer_setup_ops);
 541         if (ret)
 542                 return ret;
 543
 544         ret = ad_sd_probe_trigger(indio_dev);
 545         if (ret) {
 546                 iio_triggered_buffer_cleanup(indio_dev);
 547                 return ret;
 548         }
 549
 550         return 0;
 551 }
 552 EXPORT_SYMBOL_GPL(ad_sd_setup_buffer_and_trigger);
 553
 554 /**
 555  * ad_sd_cleanup_buffer_and_trigger() -
 556  * @indio_dev: The IIO device
 557  */
 558 void ad_sd_cleanup_buffer_and_trigger(struct iio_dev *indio_dev)
 559 {
 560         ad_sd_remove_trigger(indio_dev);
 561         iio_triggered_buffer_cleanup(indio_dev);
 562 }
 563 EXPORT_SYMBOL_GPL(ad_sd_cleanup_buffer_and_trigger);
 564
 565 /**
 566  * ad_sd_init() - Initializes a ad_sigma_delta struct
 567  * @sigma_delta: The ad_sigma_delta device
 568  * @indio_dev: The IIO device which the Sigma Delta device is used for
 569  * @spi: The SPI device for the ad_sigma_delta device
 570  * @info: Device specific callbacks and options
 571  *
 572  * This function needs to be called before any other operations are performed on
 573  * the ad_sigma_delta struct.
 574  */
 575 int ad_sd_init(struct ad_sigma_delta *sigma_delta, struct iio_dev *indio_dev,
 576         struct spi_device *spi, const struct ad_sigma_delta_info *info)
 577 {
 578         sigma_delta->spi = spi;
 579         sigma_delta->info = info;
 580         iio_device_set_drvdata(indio_dev, sigma_delta);
 581
 582         return 0;
 583 }
 584 EXPORT_SYMBOL_GPL(ad_sd_init);
 585
 586 MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
 587 MODULE_DESCRIPTION("Analog Devices Sigma-Delta ADCs");
 588 MODULE_LICENSE("GPL v2");