drivers/iio/humidity/hdc100x.c

   1 /*
   2  * hdc100x.c - Support for the TI HDC100x temperature + humidity sensors
   3  *
   4  * Copyright (C) 2015 Matt Ranostay <mranostay@gmail.com>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  14  * GNU General Public License for more details.
  15  *
  16  */
  17
  18 #include <linux/delay.h>
  19 #include <linux/module.h>
  20 #include <linux/init.h>
  21 #include <linux/i2c.h>
  22
  23 #include <linux/iio/iio.h>
  24 #include <linux/iio/sysfs.h>
  25
  26 #define HDC100X_REG_TEMP                        0x00
  27 #define HDC100X_REG_HUMIDITY                    0x01
  28
  29 #define HDC100X_REG_CONFIG                      0x02
  30 #define HDC100X_REG_CONFIG_HEATER_EN            BIT(13)
  31
  32 struct hdc100x_data {
  33         struct i2c_client *client;
  34         struct mutex lock;
  35         u16 config;
  36
  37         /* integration time of the sensor */
  38         int adc_int_us[2];
  39 };
  40
  41 /* integration time in us */
  42 static const int hdc100x_int_time[][3] = {
  43         { 6350, 3650, 0 },      /* IIO_TEMP channel*/
  44         { 6500, 3850, 2500 },   /* IIO_HUMIDITYRELATIVE channel */
  45 };
  46
  47 /* HDC100X_REG_CONFIG shift and mask values */
  48 static const struct {
  49         int shift;
  50         int mask;
  51 } hdc100x_resolution_shift[2] = {
  52         { /* IIO_TEMP channel */
  53                 .shift = 10,
  54                 .mask = 1
  55         },
  56         { /* IIO_HUMIDITYRELATIVE channel */
  57                 .shift = 8,
  58                 .mask = 2,
  59         },
  60 };
  61
  62 static IIO_CONST_ATTR(temp_integration_time_available,
  63                 "0.00365 0.00635");
  64
  65 static IIO_CONST_ATTR(humidityrelative_integration_time_available,
  66                 "0.0025 0.00385 0.0065");
  67
  68 static IIO_CONST_ATTR(out_current_heater_raw_available,
  69                 "0 1");
  70
  71 static struct attribute *hdc100x_attributes[] = {
  72         &iio_const_attr_temp_integration_time_available.dev_attr.attr,
  73         &iio_const_attr_humidityrelative_integration_time_available.dev_attr.attr,
  74         &iio_const_attr_out_current_heater_raw_available.dev_attr.attr,
  75         NULL
  76 };
  77
  78 static struct attribute_group hdc100x_attribute_group = {
  79         .attrs = hdc100x_attributes,
  80 };
  81
  82 static const struct iio_chan_spec hdc100x_channels[] = {
  83         {
  84                 .type = IIO_TEMP,
  85                 .address = HDC100X_REG_TEMP,
  86                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
  87                         BIT(IIO_CHAN_INFO_SCALE) |
  88                         BIT(IIO_CHAN_INFO_INT_TIME) |
  89                         BIT(IIO_CHAN_INFO_OFFSET),
  90         },
  91         {
  92                 .type = IIO_HUMIDITYRELATIVE,
  93                 .address = HDC100X_REG_HUMIDITY,
  94                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
  95                         BIT(IIO_CHAN_INFO_SCALE) |
  96                         BIT(IIO_CHAN_INFO_INT_TIME)
  97         },
  98         {
  99                 .type = IIO_CURRENT,
 100                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
 101                 .extend_name = "heater",
 102                 .output = 1,
 103         },
 104 };
 105
 106 static int hdc100x_update_config(struct hdc100x_data *data, int mask, int val)
 107 {
 108         int tmp = (~mask & data->config) | val;
 109         int ret;
 110
 111         ret = i2c_smbus_write_word_swapped(data->client,
 112                                                 HDC100X_REG_CONFIG, tmp);
 113         if (!ret)
 114                 data->config = tmp;
 115
 116         return ret;
 117 }
 118
 119 static int hdc100x_set_it_time(struct hdc100x_data *data, int chan, int val2)
 120 {
 121         int shift = hdc100x_resolution_shift[chan].shift;
 122         int ret = -EINVAL;
 123         int i;
 124
 125         for (i = 0; i < ARRAY_SIZE(hdc100x_int_time[chan]); i++) {
 126                 if (val2 && val2 == hdc100x_int_time[chan][i]) {
 127                         ret = hdc100x_update_config(data,
 128                                 hdc100x_resolution_shift[chan].mask << shift,
 129                                 i << shift);
 130                         if (!ret)
 131                                 data->adc_int_us[chan] = val2;
 132                         break;
 133                 }
 134         }
 135
 136         return ret;
 137 }
 138
 139 static int hdc100x_get_measurement(struct hdc100x_data *data,
 140                                    struct iio_chan_spec const *chan)
 141 {
 142         struct i2c_client *client = data->client;
 143         int delay = data->adc_int_us[chan->address];
 144         int ret;
 145         int val;
 146
 147         /* start measurement */
 148         ret = i2c_smbus_write_byte(client, chan->address);
 149         if (ret < 0) {
 150                 dev_err(&client->dev, "cannot start measurement");
 151                 return ret;
 152         }
 153
 154         /* wait for integration time to pass */
 155         usleep_range(delay, delay + 1000);
 156
 157         /*
 158          * i2c_smbus_read_word_data cannot() be used here due to the command
 159          * value not being understood and causes NAKs preventing any reading
 160          * from being accessed.
 161          */
 162         ret = i2c_smbus_read_byte(client);
 163         if (ret < 0) {
 164                 dev_err(&client->dev, "cannot read high byte measurement");
 165                 return ret;
 166         }
 167         val = ret << 6;
 168
 169         ret = i2c_smbus_read_byte(client);
 170         if (ret < 0) {
 171                 dev_err(&client->dev, "cannot read low byte measurement");
 172                 return ret;
 173         }
 174         val |= ret >> 2;
 175
 176         return val;
 177 }
 178
 179 static int hdc100x_get_heater_status(struct hdc100x_data *data)
 180 {
 181         return !!(data->config & HDC100X_REG_CONFIG_HEATER_EN);
 182 }
 183
 184 static int hdc100x_read_raw(struct iio_dev *indio_dev,
 185                             struct iio_chan_spec const *chan, int *val,
 186                             int *val2, long mask)
 187 {
 188         struct hdc100x_data *data = iio_priv(indio_dev);
 189
 190         switch (mask) {
 191         case IIO_CHAN_INFO_RAW: {
 192                 int ret;
 193
 194                 mutex_lock(&data->lock);
 195                 if (chan->type == IIO_CURRENT) {
 196                         *val = hdc100x_get_heater_status(data);
 197                         ret = IIO_VAL_INT;
 198                 } else {
 199                         ret = hdc100x_get_measurement(data, chan);
 200                         if (ret >= 0) {
 201                                 *val = ret;
 202                                 ret = IIO_VAL_INT;
 203                         }
 204                 }
 205                 mutex_unlock(&data->lock);
 206                 return ret;
 207         }
 208         case IIO_CHAN_INFO_INT_TIME:
 209                 *val = 0;
 210                 *val2 = data->adc_int_us[chan->address];
 211                 return IIO_VAL_INT_PLUS_MICRO;
 212         case IIO_CHAN_INFO_SCALE:
 213                 if (chan->type == IIO_TEMP) {
 214                         *val = 165;
 215                         *val2 = 65536 >> 2;
 216                         return IIO_VAL_FRACTIONAL;
 217                 } else {
 218                         *val = 0;
 219                         *val2 = 10000;
 220                         return IIO_VAL_INT_PLUS_MICRO;
 221                 }
 222                 break;
 223         case IIO_CHAN_INFO_OFFSET:
 224                 *val = -40;
 225                 return IIO_VAL_INT;
 226         default:
 227                 return -EINVAL;
 228         }
 229 }
 230
 231 static int hdc100x_write_raw(struct iio_dev *indio_dev,
 232                              struct iio_chan_spec const *chan,
 233                              int val, int val2, long mask)
 234 {
 235         struct hdc100x_data *data = iio_priv(indio_dev);
 236         int ret = -EINVAL;
 237
 238         switch (mask) {
 239         case IIO_CHAN_INFO_INT_TIME:
 240                 if (val != 0)
 241                         return -EINVAL;
 242
 243                 mutex_lock(&data->lock);
 244                 ret = hdc100x_set_it_time(data, chan->address, val2);
 245                 mutex_unlock(&data->lock);
 246                 return ret;
 247         case IIO_CHAN_INFO_RAW:
 248                 if (chan->type != IIO_CURRENT || val2 != 0)
 249                         return -EINVAL;
 250
 251                 mutex_lock(&data->lock);
 252                 ret = hdc100x_update_config(data, HDC100X_REG_CONFIG_HEATER_EN,
 253                                         val ? HDC100X_REG_CONFIG_HEATER_EN : 0);
 254                 mutex_unlock(&data->lock);
 255                 return ret;
 256         default:
 257                 return -EINVAL;
 258         }
 259 }
 260
 261 static const struct iio_info hdc100x_info = {
 262         .read_raw = hdc100x_read_raw,
 263         .write_raw = hdc100x_write_raw,
 264         .attrs = &hdc100x_attribute_group,
 265         .driver_module = THIS_MODULE,
 266 };
 267
 268 static int hdc100x_probe(struct i2c_client *client,
 269                          const struct i2c_device_id *id)
 270 {
 271         struct iio_dev *indio_dev;
 272         struct hdc100x_data *data;
 273
 274         if (!i2c_check_functionality(client->adapter,
 275                                 I2C_FUNC_SMBUS_WORD_DATA | I2C_FUNC_SMBUS_BYTE))
 276                 return -ENODEV;
 277
 278         indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
 279         if (!indio_dev)
 280                 return -ENOMEM;
 281
 282         data = iio_priv(indio_dev);
 283         i2c_set_clientdata(client, indio_dev);
 284         data->client = client;
 285         mutex_init(&data->lock);
 286
 287         indio_dev->dev.parent = &client->dev;
 288         indio_dev->name = dev_name(&client->dev);
 289         indio_dev->modes = INDIO_DIRECT_MODE;
 290         indio_dev->info = &hdc100x_info;
 291
 292         indio_dev->channels = hdc100x_channels;
 293         indio_dev->num_channels = ARRAY_SIZE(hdc100x_channels);
 294
 295         /* be sure we are in a known state */
 296         hdc100x_set_it_time(data, 0, hdc100x_int_time[0][0]);
 297         hdc100x_set_it_time(data, 1, hdc100x_int_time[1][0]);
 298
 299         return devm_iio_device_register(&client->dev, indio_dev);
 300 }
 301
 302 static const struct i2c_device_id hdc100x_id[] = {
 303         { "hdc100x", 0 },
 304         { }
 305 };
 306 MODULE_DEVICE_TABLE(i2c, hdc100x_id);
 307
 308 static struct i2c_driver hdc100x_driver = {
 309         .driver = {
 310                 .name   = "hdc100x",
 311         },
 312         .probe = hdc100x_probe,
 313         .id_table = hdc100x_id,
 314 };
 315 module_i2c_driver(hdc100x_driver);
 316
 317 MODULE_AUTHOR("Matt Ranostay <mranostay@gmail.com>");
 318 MODULE_DESCRIPTION("TI HDC100x humidity and temperature sensor driver");
 319 MODULE_LICENSE("GPL");