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