drivers/iio/temperature/mlx90614.c

   1 /*
   2  * mlx90614.c - Support for Melexis MLX90614 contactless IR temperature sensor
   3  *
   4  * Copyright (c) 2014 Peter Meerwald <pmeerw@pmeerw.net>
   5  * Copyright (c) 2015 Essensium NV
   6  *
   7  * This file is subject to the terms and conditions of version 2 of
   8  * the GNU General Public License.  See the file COPYING in the main
   9  * directory of this archive for more details.
  10  *
  11  * Driver for the Melexis MLX90614 I2C 16-bit IR thermopile sensor
  12  *
  13  * (7-bit I2C slave address 0x5a, 100KHz bus speed only!)
  14  *
  15  * To wake up from sleep mode, the SDA line must be held low while SCL is high
  16  * for at least 33ms.  This is achieved with an extra GPIO that can be connected
  17  * directly to the SDA line.  In normal operation, the GPIO is set as input and
  18  * will not interfere in I2C communication.  While the GPIO is driven low, the
  19  * i2c adapter is locked since it cannot be used by other clients.  The SCL line
  20  * always has a pull-up so we do not need an extra GPIO to drive it high.  If
  21  * the "wakeup" GPIO is not given, power management will be disabled.
  22  *
  23  * TODO: filter configuration
  24  */
  25
  26 #include <linux/err.h>
  27 #include <linux/i2c.h>
  28 #include <linux/module.h>
  29 #include <linux/delay.h>
  30 #include <linux/jiffies.h>
  31 #include <linux/gpio/consumer.h>
  32 #include <linux/pm_runtime.h>
  33
  34 #include <linux/iio/iio.h>
  35
  36 #define MLX90614_OP_RAM         0x00
  37 #define MLX90614_OP_EEPROM      0x20
  38 #define MLX90614_OP_SLEEP       0xff
  39
  40 /* RAM offsets with 16-bit data, MSB first */
  41 #define MLX90614_RAW1   (MLX90614_OP_RAM | 0x04) /* raw data IR channel 1 */
  42 #define MLX90614_RAW2   (MLX90614_OP_RAM | 0x05) /* raw data IR channel 2 */
  43 #define MLX90614_TA     (MLX90614_OP_RAM | 0x06) /* ambient temperature */
  44 #define MLX90614_TOBJ1  (MLX90614_OP_RAM | 0x07) /* object 1 temperature */
  45 #define MLX90614_TOBJ2  (MLX90614_OP_RAM | 0x08) /* object 2 temperature */
  46
  47 /* EEPROM offsets with 16-bit data, MSB first */
  48 #define MLX90614_EMISSIVITY     (MLX90614_OP_EEPROM | 0x04) /* emissivity correction coefficient */
  49 #define MLX90614_CONFIG         (MLX90614_OP_EEPROM | 0x05) /* configuration register */
  50
  51 /* Control bits in configuration register */
  52 #define MLX90614_CONFIG_IIR_SHIFT 0 /* IIR coefficient */
  53 #define MLX90614_CONFIG_IIR_MASK (0x7 << MLX90614_CONFIG_IIR_SHIFT)
  54 #define MLX90614_CONFIG_DUAL_SHIFT 6 /* single (0) or dual (1) IR sensor */
  55 #define MLX90614_CONFIG_DUAL_MASK (1 << MLX90614_CONFIG_DUAL_SHIFT)
  56 #define MLX90614_CONFIG_FIR_SHIFT 8 /* FIR coefficient */
  57 #define MLX90614_CONFIG_FIR_MASK (0x7 << MLX90614_CONFIG_FIR_SHIFT)
  58 #define MLX90614_CONFIG_GAIN_SHIFT 11 /* gain */
  59 #define MLX90614_CONFIG_GAIN_MASK (0x7 << MLX90614_CONFIG_GAIN_SHIFT)
  60
  61 /* Timings (in ms) */
  62 #define MLX90614_TIMING_EEPROM 20 /* time for EEPROM write/erase to complete */
  63 #define MLX90614_TIMING_WAKEUP 34 /* time to hold SDA low for wake-up */
  64 #define MLX90614_TIMING_STARTUP 250 /* time before first data after wake-up */
  65
  66 #define MLX90614_AUTOSLEEP_DELAY 5000 /* default autosleep delay */
  67
  68 /* Magic constants */
  69 #define MLX90614_CONST_OFFSET_DEC -13657 /* decimal part of the Kelvin offset */
  70 #define MLX90614_CONST_OFFSET_REM 500000 /* remainder of offset (273.15*50) */
  71 #define MLX90614_CONST_SCALE 20 /* Scale in milliKelvin (0.02 * 1000) */
  72 #define MLX90614_CONST_RAW_EMISSIVITY_MAX 65535 /* max value for emissivity */
  73 #define MLX90614_CONST_EMISSIVITY_RESOLUTION 15259 /* 1/65535 ~ 0.000015259 */
  74
  75 struct mlx90614_data {
  76         struct i2c_client *client;
  77         struct mutex lock; /* for EEPROM access only */
  78         struct gpio_desc *wakeup_gpio; /* NULL to disable sleep/wake-up */
  79         unsigned long ready_timestamp; /* in jiffies */
  80 };
  81
  82 /*
  83  * Erase an address and write word.
  84  * The mutex must be locked before calling.
  85  */
  86 static s32 mlx90614_write_word(const struct i2c_client *client, u8 command,
  87                                u16 value)
  88 {
  89         /*
  90          * Note: The mlx90614 requires a PEC on writing but does not send us a
  91          * valid PEC on reading.  Hence, we cannot set I2C_CLIENT_PEC in
  92          * i2c_client.flags.  As a workaround, we use i2c_smbus_xfer here.
  93          */
  94         union i2c_smbus_data data;
  95         s32 ret;
  96
  97         dev_dbg(&client->dev, "Writing 0x%x to address 0x%x", value, command);
  98
  99         data.word = 0x0000; /* erase command */
 100         ret = i2c_smbus_xfer(client->adapter, client->addr,
 101                              client->flags | I2C_CLIENT_PEC,
 102                              I2C_SMBUS_WRITE, command,
 103                              I2C_SMBUS_WORD_DATA, &data);
 104         if (ret < 0)
 105                 return ret;
 106
 107         msleep(MLX90614_TIMING_EEPROM);
 108
 109         data.word = value; /* actual write */
 110         ret = i2c_smbus_xfer(client->adapter, client->addr,
 111                              client->flags | I2C_CLIENT_PEC,
 112                              I2C_SMBUS_WRITE, command,
 113                              I2C_SMBUS_WORD_DATA, &data);
 114
 115         msleep(MLX90614_TIMING_EEPROM);
 116
 117         return ret;
 118 }
 119
 120 #ifdef CONFIG_PM
 121 /*
 122  * If @startup is true, make sure MLX90614_TIMING_STARTUP ms have elapsed since
 123  * the last wake-up.  This is normally only needed to get a valid temperature
 124  * reading.  EEPROM access does not need such delay.
 125  * Return 0 on success, <0 on error.
 126  */
 127 static int mlx90614_power_get(struct mlx90614_data *data, bool startup)
 128 {
 129         unsigned long now;
 130
 131         if (!data->wakeup_gpio)
 132                 return 0;
 133
 134         pm_runtime_get_sync(&data->client->dev);
 135
 136         if (startup) {
 137                 now = jiffies;
 138                 if (time_before(now, data->ready_timestamp) &&
 139                     msleep_interruptible(jiffies_to_msecs(
 140                                 data->ready_timestamp - now)) != 0) {
 141                         pm_runtime_put_autosuspend(&data->client->dev);
 142                         return -EINTR;
 143                 }
 144         }
 145
 146         return 0;
 147 }
 148
 149 static void mlx90614_power_put(struct mlx90614_data *data)
 150 {
 151         if (!data->wakeup_gpio)
 152                 return;
 153
 154         pm_runtime_mark_last_busy(&data->client->dev);
 155         pm_runtime_put_autosuspend(&data->client->dev);
 156 }
 157 #else
 158 static inline int mlx90614_power_get(struct mlx90614_data *data, bool startup)
 159 {
 160         return 0;
 161 }
 162
 163 static inline void mlx90614_power_put(struct mlx90614_data *data)
 164 {
 165 }
 166 #endif
 167
 168 static int mlx90614_read_raw(struct iio_dev *indio_dev,
 169                             struct iio_chan_spec const *channel, int *val,
 170                             int *val2, long mask)
 171 {
 172         struct mlx90614_data *data = iio_priv(indio_dev);
 173         u8 cmd;
 174         s32 ret;
 175
 176         switch (mask) {
 177         case IIO_CHAN_INFO_RAW: /* 0.02K / LSB */
 178                 switch (channel->channel2) {
 179                 case IIO_MOD_TEMP_AMBIENT:
 180                         cmd = MLX90614_TA;
 181                         break;
 182                 case IIO_MOD_TEMP_OBJECT:
 183                         switch (channel->channel) {
 184                         case 0:
 185                                 cmd = MLX90614_TOBJ1;
 186                                 break;
 187                         case 1:
 188                                 cmd = MLX90614_TOBJ2;
 189                                 break;
 190                         default:
 191                                 return -EINVAL;
 192                         }
 193                         break;
 194                 default:
 195                         return -EINVAL;
 196                 }
 197
 198                 ret = mlx90614_power_get(data, true);
 199                 if (ret < 0)
 200                         return ret;
 201                 ret = i2c_smbus_read_word_data(data->client, cmd);
 202                 mlx90614_power_put(data);
 203
 204                 if (ret < 0)
 205                         return ret;
 206
 207                 /* MSB is an error flag */
 208                 if (ret & 0x8000)
 209                         return -EIO;
 210
 211                 *val = ret;
 212                 return IIO_VAL_INT;
 213         case IIO_CHAN_INFO_OFFSET:
 214                 *val = MLX90614_CONST_OFFSET_DEC;
 215                 *val2 = MLX90614_CONST_OFFSET_REM;
 216                 return IIO_VAL_INT_PLUS_MICRO;
 217         case IIO_CHAN_INFO_SCALE:
 218                 *val = MLX90614_CONST_SCALE;
 219                 return IIO_VAL_INT;
 220         case IIO_CHAN_INFO_CALIBEMISSIVITY: /* 1/65535 / LSB */
 221                 mlx90614_power_get(data, false);
 222                 mutex_lock(&data->lock);
 223                 ret = i2c_smbus_read_word_data(data->client,
 224                                                MLX90614_EMISSIVITY);
 225                 mutex_unlock(&data->lock);
 226                 mlx90614_power_put(data);
 227
 228                 if (ret < 0)
 229                         return ret;
 230
 231                 if (ret == MLX90614_CONST_RAW_EMISSIVITY_MAX) {
 232                         *val = 1;
 233                         *val2 = 0;
 234                 } else {
 235                         *val = 0;
 236                         *val2 = ret * MLX90614_CONST_EMISSIVITY_RESOLUTION;
 237                 }
 238                 return IIO_VAL_INT_PLUS_NANO;
 239         default:
 240                 return -EINVAL;
 241         }
 242 }
 243
 244 static int mlx90614_write_raw(struct iio_dev *indio_dev,
 245                              struct iio_chan_spec const *channel, int val,
 246                              int val2, long mask)
 247 {
 248         struct mlx90614_data *data = iio_priv(indio_dev);
 249         s32 ret;
 250
 251         switch (mask) {
 252         case IIO_CHAN_INFO_CALIBEMISSIVITY: /* 1/65535 / LSB */
 253                 if (val < 0 || val2 < 0 || val > 1 || (val == 1 && val2 != 0))
 254                         return -EINVAL;
 255                 val = val * MLX90614_CONST_RAW_EMISSIVITY_MAX +
 256                         val2 / MLX90614_CONST_EMISSIVITY_RESOLUTION;
 257
 258                 mlx90614_power_get(data, false);
 259                 mutex_lock(&data->lock);
 260                 ret = mlx90614_write_word(data->client, MLX90614_EMISSIVITY,
 261                                           val);
 262                 mutex_unlock(&data->lock);
 263                 mlx90614_power_put(data);
 264
 265                 return ret;
 266         default:
 267                 return -EINVAL;
 268         }
 269 }
 270
 271 static int mlx90614_write_raw_get_fmt(struct iio_dev *indio_dev,
 272                                      struct iio_chan_spec const *channel,
 273                                      long mask)
 274 {
 275         switch (mask) {
 276         case IIO_CHAN_INFO_CALIBEMISSIVITY:
 277                 return IIO_VAL_INT_PLUS_NANO;
 278         default:
 279                 return -EINVAL;
 280         }
 281 }
 282
 283 static const struct iio_chan_spec mlx90614_channels[] = {
 284         {
 285                 .type = IIO_TEMP,
 286                 .modified = 1,
 287                 .channel2 = IIO_MOD_TEMP_AMBIENT,
 288                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
 289                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_OFFSET) |
 290                     BIT(IIO_CHAN_INFO_SCALE),
 291         },
 292         {
 293                 .type = IIO_TEMP,
 294                 .modified = 1,
 295                 .channel2 = IIO_MOD_TEMP_OBJECT,
 296                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
 297                     BIT(IIO_CHAN_INFO_CALIBEMISSIVITY),
 298                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_OFFSET) |
 299                     BIT(IIO_CHAN_INFO_SCALE),
 300         },
 301         {
 302                 .type = IIO_TEMP,
 303                 .indexed = 1,
 304                 .modified = 1,
 305                 .channel = 1,
 306                 .channel2 = IIO_MOD_TEMP_OBJECT,
 307                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
 308                     BIT(IIO_CHAN_INFO_CALIBEMISSIVITY),
 309                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_OFFSET) |
 310                     BIT(IIO_CHAN_INFO_SCALE),
 311         },
 312 };
 313
 314 static const struct iio_info mlx90614_info = {
 315         .read_raw = mlx90614_read_raw,
 316         .write_raw = mlx90614_write_raw,
 317         .write_raw_get_fmt = mlx90614_write_raw_get_fmt,
 318         .driver_module = THIS_MODULE,
 319 };
 320
 321 #ifdef CONFIG_PM
 322 static int mlx90614_sleep(struct mlx90614_data *data)
 323 {
 324         s32 ret;
 325
 326         if (!data->wakeup_gpio) {
 327                 dev_dbg(&data->client->dev, "Sleep disabled");
 328                 return -ENOSYS;
 329         }
 330
 331         dev_dbg(&data->client->dev, "Requesting sleep");
 332
 333         mutex_lock(&data->lock);
 334         ret = i2c_smbus_xfer(data->client->adapter, data->client->addr,
 335                              data->client->flags | I2C_CLIENT_PEC,
 336                              I2C_SMBUS_WRITE, MLX90614_OP_SLEEP,
 337                              I2C_SMBUS_BYTE, NULL);
 338         mutex_unlock(&data->lock);
 339
 340         return ret;
 341 }
 342
 343 static int mlx90614_wakeup(struct mlx90614_data *data)
 344 {
 345         if (!data->wakeup_gpio) {
 346                 dev_dbg(&data->client->dev, "Wake-up disabled");
 347                 return -ENOSYS;
 348         }
 349
 350         dev_dbg(&data->client->dev, "Requesting wake-up");
 351
 352         i2c_lock_adapter(data->client->adapter);
 353         gpiod_direction_output(data->wakeup_gpio, 0);
 354         msleep(MLX90614_TIMING_WAKEUP);
 355         gpiod_direction_input(data->wakeup_gpio);
 356         i2c_unlock_adapter(data->client->adapter);
 357
 358         data->ready_timestamp = jiffies +
 359                         msecs_to_jiffies(MLX90614_TIMING_STARTUP);
 360
 361         /*
 362          * Quirk: the i2c controller may get confused right after the
 363          * wake-up signal has been sent.  As a workaround, do a dummy read.
 364          * If the read fails, the controller will probably be reset so that
 365          * further reads will work.
 366          */
 367         i2c_smbus_read_word_data(data->client, MLX90614_CONFIG);
 368
 369         return 0;
 370 }
 371
 372 /* Return wake-up GPIO or NULL if sleep functionality should be disabled. */
 373 static struct gpio_desc *mlx90614_probe_wakeup(struct i2c_client *client)
 374 {
 375         struct gpio_desc *gpio;
 376
 377         if (!i2c_check_functionality(client->adapter,
 378                                                 I2C_FUNC_SMBUS_WRITE_BYTE)) {
 379                 dev_info(&client->dev,
 380                          "i2c adapter does not support SMBUS_WRITE_BYTE, sleep disabled");
 381                 return NULL;
 382         }
 383
 384         gpio = devm_gpiod_get_optional(&client->dev, "wakeup", GPIOD_IN);
 385
 386         if (IS_ERR(gpio)) {
 387                 dev_warn(&client->dev,
 388                          "gpio acquisition failed with error %ld, sleep disabled",
 389                          PTR_ERR(gpio));
 390                 return NULL;
 391         } else if (!gpio) {
 392                 dev_info(&client->dev,
 393                          "wakeup-gpio not found, sleep disabled");
 394         }
 395
 396         return gpio;
 397 }
 398 #else
 399 static inline int mlx90614_sleep(struct mlx90614_data *data)
 400 {
 401         return -ENOSYS;
 402 }
 403 static inline int mlx90614_wakeup(struct mlx90614_data *data)
 404 {
 405         return -ENOSYS;
 406 }
 407 static inline struct gpio_desc *mlx90614_probe_wakeup(struct i2c_client *client)
 408 {
 409         return NULL;
 410 }
 411 #endif
 412
 413 /* Return 0 for single sensor, 1 for dual sensor, <0 on error. */
 414 static int mlx90614_probe_num_ir_sensors(struct i2c_client *client)
 415 {
 416         s32 ret;
 417
 418         ret = i2c_smbus_read_word_data(client, MLX90614_CONFIG);
 419
 420         if (ret < 0)
 421                 return ret;
 422
 423         return (ret & MLX90614_CONFIG_DUAL_MASK) ? 1 : 0;
 424 }
 425
 426 static int mlx90614_probe(struct i2c_client *client,
 427                          const struct i2c_device_id *id)
 428 {
 429         struct iio_dev *indio_dev;
 430         struct mlx90614_data *data;
 431         int ret;
 432
 433         if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WORD_DATA))
 434                 return -ENODEV;
 435
 436         indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
 437         if (!indio_dev)
 438                 return -ENOMEM;
 439
 440         data = iio_priv(indio_dev);
 441         i2c_set_clientdata(client, indio_dev);
 442         data->client = client;
 443         mutex_init(&data->lock);
 444         data->wakeup_gpio = mlx90614_probe_wakeup(client);
 445
 446         mlx90614_wakeup(data);
 447
 448         indio_dev->dev.parent = &client->dev;
 449         indio_dev->name = id->name;
 450         indio_dev->modes = INDIO_DIRECT_MODE;
 451         indio_dev->info = &mlx90614_info;
 452
 453         ret = mlx90614_probe_num_ir_sensors(client);
 454         switch (ret) {
 455         case 0:
 456                 dev_dbg(&client->dev, "Found single sensor");
 457                 indio_dev->channels = mlx90614_channels;
 458                 indio_dev->num_channels = 2;
 459                 break;
 460         case 1:
 461                 dev_dbg(&client->dev, "Found dual sensor");
 462                 indio_dev->channels = mlx90614_channels;
 463                 indio_dev->num_channels = 3;
 464                 break;
 465         default:
 466                 return ret;
 467         }
 468
 469         if (data->wakeup_gpio) {
 470                 pm_runtime_set_autosuspend_delay(&client->dev,
 471                                                  MLX90614_AUTOSLEEP_DELAY);
 472                 pm_runtime_use_autosuspend(&client->dev);
 473                 pm_runtime_set_active(&client->dev);
 474                 pm_runtime_enable(&client->dev);
 475         }
 476
 477         return iio_device_register(indio_dev);
 478 }
 479
 480 static int mlx90614_remove(struct i2c_client *client)
 481 {
 482         struct iio_dev *indio_dev = i2c_get_clientdata(client);
 483         struct mlx90614_data *data = iio_priv(indio_dev);
 484
 485         iio_device_unregister(indio_dev);
 486
 487         if (data->wakeup_gpio) {
 488                 pm_runtime_disable(&client->dev);
 489                 if (!pm_runtime_status_suspended(&client->dev))
 490                         mlx90614_sleep(data);
 491                 pm_runtime_set_suspended(&client->dev);
 492         }
 493
 494         return 0;
 495 }
 496
 497 static const struct i2c_device_id mlx90614_id[] = {
 498         { "mlx90614", 0 },
 499         { }
 500 };
 501 MODULE_DEVICE_TABLE(i2c, mlx90614_id);
 502
 503 #ifdef CONFIG_PM_SLEEP
 504 static int mlx90614_pm_suspend(struct device *dev)
 505 {
 506         struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
 507         struct mlx90614_data *data = iio_priv(indio_dev);
 508
 509         if (data->wakeup_gpio && pm_runtime_active(dev))
 510                 return mlx90614_sleep(data);
 511
 512         return 0;
 513 }
 514
 515 static int mlx90614_pm_resume(struct device *dev)
 516 {
 517         struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
 518         struct mlx90614_data *data = iio_priv(indio_dev);
 519         int err;
 520
 521         if (data->wakeup_gpio) {
 522                 err = mlx90614_wakeup(data);
 523                 if (err < 0)
 524                         return err;
 525
 526                 pm_runtime_disable(dev);
 527                 pm_runtime_set_active(dev);
 528                 pm_runtime_enable(dev);
 529         }
 530
 531         return 0;
 532 }
 533 #endif
 534
 535 #ifdef CONFIG_PM
 536 static int mlx90614_pm_runtime_suspend(struct device *dev)
 537 {
 538         struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
 539         struct mlx90614_data *data = iio_priv(indio_dev);
 540
 541         return mlx90614_sleep(data);
 542 }
 543
 544 static int mlx90614_pm_runtime_resume(struct device *dev)
 545 {
 546         struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
 547         struct mlx90614_data *data = iio_priv(indio_dev);
 548
 549         return mlx90614_wakeup(data);
 550 }
 551 #endif
 552
 553 static const struct dev_pm_ops mlx90614_pm_ops = {
 554         SET_SYSTEM_SLEEP_PM_OPS(mlx90614_pm_suspend, mlx90614_pm_resume)
 555         SET_RUNTIME_PM_OPS(mlx90614_pm_runtime_suspend,
 556                            mlx90614_pm_runtime_resume, NULL)
 557 };
 558
 559 static struct i2c_driver mlx90614_driver = {
 560         .driver = {
 561                 .name   = "mlx90614",
 562                 .pm     = &mlx90614_pm_ops,
 563         },
 564         .probe = mlx90614_probe,
 565         .remove = mlx90614_remove,
 566         .id_table = mlx90614_id,
 567 };
 568 module_i2c_driver(mlx90614_driver);
 569
 570 MODULE_AUTHOR("Peter Meerwald <pmeerw@pmeerw.net>");
 571 MODULE_AUTHOR("Vianney le Clément de Saint-Marcq <vianney.leclement@essensium.com>");
 572 MODULE_DESCRIPTION("Melexis MLX90614 contactless IR temperature sensor driver");
 573 MODULE_LICENSE("GPL");