drivers/iio/adc/ad7291.c

   1 /*
   2  * AD7291 8-Channel, I2C, 12-Bit SAR ADC with Temperature Sensor
   3  *
   4  * Copyright 2010-2011 Analog Devices Inc.
   5  *
   6  * Licensed under the GPL-2 or later.
   7  */
   8
   9 #include <linux/device.h>
  10 #include <linux/err.h>
  11 #include <linux/i2c.h>
  12 #include <linux/interrupt.h>
  13 #include <linux/kernel.h>
  14 #include <linux/module.h>
  15 #include <linux/mutex.h>
  16 #include <linux/regulator/consumer.h>
  17 #include <linux/slab.h>
  18 #include <linux/sysfs.h>
  19
  20 #include <linux/iio/iio.h>
  21 #include <linux/iio/sysfs.h>
  22 #include <linux/iio/events.h>
  23
  24 #include <linux/platform_data/ad7291.h>
  25
  26 /*
  27  * Simplified handling
  28  *
  29  * If no events enabled - single polled channel read
  30  * If event enabled direct reads disable unless channel
  31  * is in the read mask.
  32  *
  33  * The noise-delayed bit as per datasheet suggestion is always enabled.
  34  */
  35
  36 /*
  37  * AD7291 registers definition
  38  */
  39 #define AD7291_COMMAND                  0x00
  40 #define AD7291_VOLTAGE                  0x01
  41 #define AD7291_T_SENSE                  0x02
  42 #define AD7291_T_AVERAGE                0x03
  43 #define AD7291_DATA_HIGH(x)             ((x) * 3 + 0x4)
  44 #define AD7291_DATA_LOW(x)              ((x) * 3 + 0x5)
  45 #define AD7291_HYST(x)                  ((x) * 3 + 0x6)
  46 #define AD7291_VOLTAGE_ALERT_STATUS     0x1F
  47 #define AD7291_T_ALERT_STATUS           0x20
  48
  49 #define AD7291_BITS                     12
  50 #define AD7291_VOLTAGE_LIMIT_COUNT      8
  51
  52
  53 /*
  54  * AD7291 command
  55  */
  56 #define AD7291_AUTOCYCLE                BIT(0)
  57 #define AD7291_RESET                    BIT(1)
  58 #define AD7291_ALERT_CLEAR              BIT(2)
  59 #define AD7291_ALERT_POLARITY           BIT(3)
  60 #define AD7291_EXT_REF                  BIT(4)
  61 #define AD7291_NOISE_DELAY              BIT(5)
  62 #define AD7291_T_SENSE_MASK             BIT(7)
  63 #define AD7291_VOLTAGE_MASK             GENMASK(15, 8)
  64 #define AD7291_VOLTAGE_OFFSET           8
  65
  66 /*
  67  * AD7291 value masks
  68  */
  69 #define AD7291_VALUE_MASK               GENMASK(11, 0)
  70
  71 /*
  72  * AD7291 alert register bits
  73  */
  74 #define AD7291_T_LOW                    BIT(0)
  75 #define AD7291_T_HIGH                   BIT(1)
  76 #define AD7291_T_AVG_LOW                BIT(2)
  77 #define AD7291_T_AVG_HIGH               BIT(3)
  78 #define AD7291_V_LOW(x)                 BIT((x) * 2)
  79 #define AD7291_V_HIGH(x)                BIT((x) * 2 + 1)
  80
  81
  82 struct ad7291_chip_info {
  83         struct i2c_client       *client;
  84         struct regulator        *reg;
  85         u16                     command;
  86         u16                     c_mask; /* Active voltage channels for events */
  87         struct mutex            state_lock;
  88 };
  89
  90 static int ad7291_i2c_read(struct ad7291_chip_info *chip, u8 reg, u16 *data)
  91 {
  92         struct i2c_client *client = chip->client;
  93         int ret = 0;
  94
  95         ret = i2c_smbus_read_word_swapped(client, reg);
  96         if (ret < 0) {
  97                 dev_err(&client->dev, "I2C read error\n");
  98                 return ret;
  99         }
 100
 101         *data = ret;
 102
 103         return 0;
 104 }
 105
 106 static int ad7291_i2c_write(struct ad7291_chip_info *chip, u8 reg, u16 data)
 107 {
 108         return i2c_smbus_write_word_swapped(chip->client, reg, data);
 109 }
 110
 111 static irqreturn_t ad7291_event_handler(int irq, void *private)
 112 {
 113         struct iio_dev *indio_dev = private;
 114         struct ad7291_chip_info *chip = iio_priv(private);
 115         u16 t_status, v_status;
 116         u16 command;
 117         int i;
 118         s64 timestamp = iio_get_time_ns();
 119
 120         if (ad7291_i2c_read(chip, AD7291_T_ALERT_STATUS, &t_status))
 121                 return IRQ_HANDLED;
 122
 123         if (ad7291_i2c_read(chip, AD7291_VOLTAGE_ALERT_STATUS, &v_status))
 124                 return IRQ_HANDLED;
 125
 126         if (!(t_status || v_status))
 127                 return IRQ_HANDLED;
 128
 129         command = chip->command | AD7291_ALERT_CLEAR;
 130         ad7291_i2c_write(chip, AD7291_COMMAND, command);
 131
 132         command = chip->command & ~AD7291_ALERT_CLEAR;
 133         ad7291_i2c_write(chip, AD7291_COMMAND, command);
 134
 135         /* For now treat t_sense and t_sense_average the same */
 136         if ((t_status & AD7291_T_LOW) || (t_status & AD7291_T_AVG_LOW))
 137                 iio_push_event(indio_dev,
 138                                IIO_UNMOD_EVENT_CODE(IIO_TEMP,
 139                                                     0,
 140                                                     IIO_EV_TYPE_THRESH,
 141                                                     IIO_EV_DIR_FALLING),
 142                                timestamp);
 143         if ((t_status & AD7291_T_HIGH) || (t_status & AD7291_T_AVG_HIGH))
 144                 iio_push_event(indio_dev,
 145                                IIO_UNMOD_EVENT_CODE(IIO_TEMP,
 146                                                     0,
 147                                                     IIO_EV_TYPE_THRESH,
 148                                                     IIO_EV_DIR_RISING),
 149                                timestamp);
 150
 151         for (i = 0; i < AD7291_VOLTAGE_LIMIT_COUNT; i++) {
 152                 if (v_status & AD7291_V_LOW(i))
 153                         iio_push_event(indio_dev,
 154                                        IIO_UNMOD_EVENT_CODE(IIO_VOLTAGE,
 155                                                             i,
 156                                                             IIO_EV_TYPE_THRESH,
 157                                                             IIO_EV_DIR_FALLING),
 158                                        timestamp);
 159                 if (v_status & AD7291_V_HIGH(i))
 160                         iio_push_event(indio_dev,
 161                                        IIO_UNMOD_EVENT_CODE(IIO_VOLTAGE,
 162                                                             i,
 163                                                             IIO_EV_TYPE_THRESH,
 164                                                             IIO_EV_DIR_RISING),
 165                                        timestamp);
 166         }
 167
 168         return IRQ_HANDLED;
 169 }
 170
 171 static unsigned int ad7291_threshold_reg(const struct iio_chan_spec *chan,
 172                                          enum iio_event_direction dir,
 173                                          enum iio_event_info info)
 174 {
 175         unsigned int offset;
 176
 177         switch (chan->type) {
 178         case IIO_VOLTAGE:
 179                 offset = chan->channel;
 180                 break;
 181         case IIO_TEMP:
 182                 offset = AD7291_VOLTAGE_OFFSET;
 183                 break;
 184         default:
 185             return 0;
 186         }
 187
 188         switch (info) {
 189         case IIO_EV_INFO_VALUE:
 190                 if (dir == IIO_EV_DIR_FALLING)
 191                         return AD7291_DATA_HIGH(offset);
 192                 else
 193                         return AD7291_DATA_LOW(offset);
 194         case IIO_EV_INFO_HYSTERESIS:
 195                 return AD7291_HYST(offset);
 196         default:
 197                 break;
 198         }
 199         return 0;
 200 }
 201
 202 static int ad7291_read_event_value(struct iio_dev *indio_dev,
 203                                    const struct iio_chan_spec *chan,
 204                                    enum iio_event_type type,
 205                                    enum iio_event_direction dir,
 206                                    enum iio_event_info info,
 207                                    int *val, int *val2)
 208 {
 209         struct ad7291_chip_info *chip = iio_priv(indio_dev);
 210         int ret;
 211         u16 uval;
 212
 213         ret = ad7291_i2c_read(chip, ad7291_threshold_reg(chan, dir, info),
 214                               &uval);
 215         if (ret < 0)
 216                 return ret;
 217
 218         if (info == IIO_EV_INFO_HYSTERESIS || chan->type == IIO_VOLTAGE)
 219                 *val = uval & AD7291_VALUE_MASK;
 220
 221         else
 222                 *val = sign_extend32(uval, 11);
 223
 224         return IIO_VAL_INT;
 225 }
 226
 227 static int ad7291_write_event_value(struct iio_dev *indio_dev,
 228                                     const struct iio_chan_spec *chan,
 229                                     enum iio_event_type type,
 230                                     enum iio_event_direction dir,
 231                                     enum iio_event_info info,
 232                                     int val, int val2)
 233 {
 234         struct ad7291_chip_info *chip = iio_priv(indio_dev);
 235
 236         if (info == IIO_EV_INFO_HYSTERESIS || chan->type == IIO_VOLTAGE) {
 237                 if (val > AD7291_VALUE_MASK || val < 0)
 238                         return -EINVAL;
 239         } else {
 240                 if (val > 2047 || val < -2048)
 241                         return -EINVAL;
 242         }
 243
 244         return ad7291_i2c_write(chip, ad7291_threshold_reg(chan, dir, info),
 245                                 val);
 246 }
 247
 248 static int ad7291_read_event_config(struct iio_dev *indio_dev,
 249                                     const struct iio_chan_spec *chan,
 250                                     enum iio_event_type type,
 251                                     enum iio_event_direction dir)
 252 {
 253         struct ad7291_chip_info *chip = iio_priv(indio_dev);
 254         /*
 255          * To be enabled the channel must simply be on. If any are enabled
 256          * we are in continuous sampling mode
 257          */
 258
 259         switch (chan->type) {
 260         case IIO_VOLTAGE:
 261                 return !!(chip->c_mask & BIT(15 - chan->channel));
 262         case IIO_TEMP:
 263                 /* always on */
 264                 return 1;
 265         default:
 266                 return -EINVAL;
 267         }
 268
 269 }
 270
 271 static int ad7291_write_event_config(struct iio_dev *indio_dev,
 272                                      const struct iio_chan_spec *chan,
 273                                      enum iio_event_type type,
 274                                      enum iio_event_direction dir,
 275                                      int state)
 276 {
 277         int ret = 0;
 278         struct ad7291_chip_info *chip = iio_priv(indio_dev);
 279         unsigned int mask;
 280         u16 regval;
 281
 282         mutex_lock(&chip->state_lock);
 283         regval = chip->command;
 284         /*
 285          * To be enabled the channel must simply be on. If any are enabled
 286          * use continuous sampling mode.
 287          * Possible to disable temp as well but that makes single read tricky.
 288          */
 289
 290         mask = BIT(15 - chan->channel);
 291
 292         switch (chan->type) {
 293         case IIO_VOLTAGE:
 294                 if ((!state) && (chip->c_mask & mask))
 295                         chip->c_mask &= ~mask;
 296                 else if (state && (!(chip->c_mask & mask)))
 297                         chip->c_mask |= mask;
 298                 else
 299                         break;
 300
 301                 regval &= ~AD7291_AUTOCYCLE;
 302                 regval |= chip->c_mask;
 303                 if (chip->c_mask) /* Enable autocycle? */
 304                         regval |= AD7291_AUTOCYCLE;
 305
 306                 ret = ad7291_i2c_write(chip, AD7291_COMMAND, regval);
 307                 if (ret < 0)
 308                         goto error_ret;
 309
 310                 chip->command = regval;
 311                 break;
 312         default:
 313                 ret = -EINVAL;
 314         }
 315
 316 error_ret:
 317         mutex_unlock(&chip->state_lock);
 318         return ret;
 319 }
 320
 321 static int ad7291_read_raw(struct iio_dev *indio_dev,
 322                            struct iio_chan_spec const *chan,
 323                            int *val,
 324                            int *val2,
 325                            long mask)
 326 {
 327         int ret;
 328         struct ad7291_chip_info *chip = iio_priv(indio_dev);
 329         u16 regval;
 330
 331         switch (mask) {
 332         case IIO_CHAN_INFO_RAW:
 333                 switch (chan->type) {
 334                 case IIO_VOLTAGE:
 335                         mutex_lock(&chip->state_lock);
 336                         /* If in autocycle mode drop through */
 337                         if (chip->command & AD7291_AUTOCYCLE) {
 338                                 mutex_unlock(&chip->state_lock);
 339                                 return -EBUSY;
 340                         }
 341                         /* Enable this channel alone */
 342                         regval = chip->command & (~AD7291_VOLTAGE_MASK);
 343                         regval |= BIT(15 - chan->channel);
 344                         ret = ad7291_i2c_write(chip, AD7291_COMMAND, regval);
 345                         if (ret < 0) {
 346                                 mutex_unlock(&chip->state_lock);
 347                                 return ret;
 348                         }
 349                         /* Read voltage */
 350                         ret = i2c_smbus_read_word_swapped(chip->client,
 351                                                           AD7291_VOLTAGE);
 352                         if (ret < 0) {
 353                                 mutex_unlock(&chip->state_lock);
 354                                 return ret;
 355                         }
 356                         *val = ret & AD7291_VALUE_MASK;
 357                         mutex_unlock(&chip->state_lock);
 358                         return IIO_VAL_INT;
 359                 case IIO_TEMP:
 360                         /* Assumes tsense bit of command register always set */
 361                         ret = i2c_smbus_read_word_swapped(chip->client,
 362                                                           AD7291_T_SENSE);
 363                         if (ret < 0)
 364                                 return ret;
 365                         *val = sign_extend32(ret, 11);
 366                         return IIO_VAL_INT;
 367                 default:
 368                         return -EINVAL;
 369                 }
 370         case IIO_CHAN_INFO_AVERAGE_RAW:
 371                 ret = i2c_smbus_read_word_swapped(chip->client,
 372                                                   AD7291_T_AVERAGE);
 373                         if (ret < 0)
 374                                 return ret;
 375                         *val = sign_extend32(ret, 11);
 376                         return IIO_VAL_INT;
 377         case IIO_CHAN_INFO_SCALE:
 378                 switch (chan->type) {
 379                 case IIO_VOLTAGE:
 380                         if (chip->reg) {
 381                                 int vref;
 382
 383                                 vref = regulator_get_voltage(chip->reg);
 384                                 if (vref < 0)
 385                                         return vref;
 386                                 *val = vref / 1000;
 387                         } else {
 388                                 *val = 2500;
 389                         }
 390                         *val2 = AD7291_BITS;
 391                         return IIO_VAL_FRACTIONAL_LOG2;
 392                 case IIO_TEMP:
 393                         /*
 394                          * One LSB of the ADC corresponds to 0.25 deg C.
 395                          * The temperature reading is in 12-bit twos
 396                          * complement format
 397                          */
 398                         *val = 250;
 399                         return IIO_VAL_INT;
 400                 default:
 401                         return -EINVAL;
 402                 }
 403         default:
 404                 return -EINVAL;
 405         }
 406 }
 407
 408 static const struct iio_event_spec ad7291_events[] = {
 409         {
 410                 .type = IIO_EV_TYPE_THRESH,
 411                 .dir = IIO_EV_DIR_RISING,
 412                 .mask_separate = BIT(IIO_EV_INFO_VALUE) |
 413                         BIT(IIO_EV_INFO_ENABLE),
 414         }, {
 415                 .type = IIO_EV_TYPE_THRESH,
 416                 .dir = IIO_EV_DIR_FALLING,
 417                 .mask_separate = BIT(IIO_EV_INFO_VALUE) |
 418                         BIT(IIO_EV_INFO_ENABLE),
 419         }, {
 420                 .type = IIO_EV_TYPE_THRESH,
 421                 .dir = IIO_EV_DIR_EITHER,
 422                 .mask_separate = BIT(IIO_EV_INFO_HYSTERESIS),
 423         },
 424 };
 425
 426 #define AD7291_VOLTAGE_CHAN(_chan)                                      \
 427 {                                                                       \
 428         .type = IIO_VOLTAGE,                                            \
 429         .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),                   \
 430         .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),           \
 431         .indexed = 1,                                                   \
 432         .channel = _chan,                                               \
 433         .event_spec = ad7291_events,                                    \
 434         .num_event_specs = ARRAY_SIZE(ad7291_events),                   \
 435 }
 436
 437 static const struct iio_chan_spec ad7291_channels[] = {
 438         AD7291_VOLTAGE_CHAN(0),
 439         AD7291_VOLTAGE_CHAN(1),
 440         AD7291_VOLTAGE_CHAN(2),
 441         AD7291_VOLTAGE_CHAN(3),
 442         AD7291_VOLTAGE_CHAN(4),
 443         AD7291_VOLTAGE_CHAN(5),
 444         AD7291_VOLTAGE_CHAN(6),
 445         AD7291_VOLTAGE_CHAN(7),
 446         {
 447                 .type = IIO_TEMP,
 448                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
 449                                 BIT(IIO_CHAN_INFO_AVERAGE_RAW) |
 450                                 BIT(IIO_CHAN_INFO_SCALE),
 451                 .indexed = 1,
 452                 .channel = 0,
 453                 .event_spec = ad7291_events,
 454                 .num_event_specs = ARRAY_SIZE(ad7291_events),
 455         }
 456 };
 457
 458 static const struct iio_info ad7291_info = {
 459         .read_raw = &ad7291_read_raw,
 460         .read_event_config = &ad7291_read_event_config,
 461         .write_event_config = &ad7291_write_event_config,
 462         .read_event_value = &ad7291_read_event_value,
 463         .write_event_value = &ad7291_write_event_value,
 464         .driver_module = THIS_MODULE,
 465 };
 466
 467 static int ad7291_probe(struct i2c_client *client,
 468                         const struct i2c_device_id *id)
 469 {
 470         struct ad7291_platform_data *pdata = client->dev.platform_data;
 471         struct ad7291_chip_info *chip;
 472         struct iio_dev *indio_dev;
 473         int ret;
 474
 475         indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*chip));
 476         if (!indio_dev)
 477                 return -ENOMEM;
 478         chip = iio_priv(indio_dev);
 479
 480         if (pdata && pdata->use_external_ref) {
 481                 chip->reg = devm_regulator_get(&client->dev, "vref");
 482                 if (IS_ERR(chip->reg))
 483                         return PTR_ERR(chip->reg);
 484
 485                 ret = regulator_enable(chip->reg);
 486                 if (ret)
 487                         return ret;
 488         }
 489
 490         mutex_init(&chip->state_lock);
 491         /* this is only used for device removal purposes */
 492         i2c_set_clientdata(client, indio_dev);
 493
 494         chip->client = client;
 495
 496         chip->command = AD7291_NOISE_DELAY |
 497                         AD7291_T_SENSE_MASK | /* Tsense always enabled */
 498                         AD7291_ALERT_POLARITY; /* set irq polarity low level */
 499
 500         if (pdata && pdata->use_external_ref)
 501                 chip->command |= AD7291_EXT_REF;
 502
 503         indio_dev->name = id->name;
 504         indio_dev->channels = ad7291_channels;
 505         indio_dev->num_channels = ARRAY_SIZE(ad7291_channels);
 506
 507         indio_dev->dev.parent = &client->dev;
 508         indio_dev->info = &ad7291_info;
 509         indio_dev->modes = INDIO_DIRECT_MODE;
 510
 511         ret = ad7291_i2c_write(chip, AD7291_COMMAND, AD7291_RESET);
 512         if (ret) {
 513                 ret = -EIO;
 514                 goto error_disable_reg;
 515         }
 516
 517         ret = ad7291_i2c_write(chip, AD7291_COMMAND, chip->command);
 518         if (ret) {
 519                 ret = -EIO;
 520                 goto error_disable_reg;
 521         }
 522
 523         if (client->irq > 0) {
 524                 ret = request_threaded_irq(client->irq,
 525                                            NULL,
 526                                            &ad7291_event_handler,
 527                                            IRQF_TRIGGER_LOW | IRQF_ONESHOT,
 528                                            id->name,
 529                                            indio_dev);
 530                 if (ret)
 531                         goto error_disable_reg;
 532         }
 533
 534         ret = iio_device_register(indio_dev);
 535         if (ret)
 536                 goto error_unreg_irq;
 537
 538         return 0;
 539
 540 error_unreg_irq:
 541         if (client->irq)
 542                 free_irq(client->irq, indio_dev);
 543 error_disable_reg:
 544         if (chip->reg)
 545                 regulator_disable(chip->reg);
 546
 547         return ret;
 548 }
 549
 550 static int ad7291_remove(struct i2c_client *client)
 551 {
 552         struct iio_dev *indio_dev = i2c_get_clientdata(client);
 553         struct ad7291_chip_info *chip = iio_priv(indio_dev);
 554
 555         iio_device_unregister(indio_dev);
 556
 557         if (client->irq)
 558                 free_irq(client->irq, indio_dev);
 559
 560         if (chip->reg)
 561                 regulator_disable(chip->reg);
 562
 563         return 0;
 564 }
 565
 566 static const struct i2c_device_id ad7291_id[] = {
 567         { "ad7291", 0 },
 568         {}
 569 };
 570
 571 MODULE_DEVICE_TABLE(i2c, ad7291_id);
 572
 573 static struct i2c_driver ad7291_driver = {
 574         .driver = {
 575                 .name = KBUILD_MODNAME,
 576         },
 577         .probe = ad7291_probe,
 578         .remove = ad7291_remove,
 579         .id_table = ad7291_id,
 580 };
 581 module_i2c_driver(ad7291_driver);
 582
 583 MODULE_AUTHOR("Sonic Zhang <sonic.zhang@analog.com>");
 584 MODULE_DESCRIPTION("Analog Devices AD7291 ADC driver");
 585 MODULE_LICENSE("GPL v2");