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