drivers/iio/adc/mcp3422.c

   1 /*
   2  * mcp3422.c - driver for the Microchip mcp3422/3/4/6/7/8 chip family
   3  *
   4  * Copyright (C) 2013, Angelo Compagnucci
   5  * Author: Angelo Compagnucci <angelo.compagnucci@gmail.com>
   6  *
   7  * Datasheet: http://ww1.microchip.com/downloads/en/devicedoc/22088b.pdf
   8  *            http://ww1.microchip.com/downloads/en/DeviceDoc/22226a.pdf
   9  *
  10  * This driver exports the value of analog input voltage to sysfs, the
  11  * voltage unit is nV.
  12  *
  13  * This program is free software; you can redistribute it and/or modify
  14  * it under the terms of the GNU General Public License as published by
  15  * the Free Software Foundation; either version 2 of the License, or
  16  * (at your option) any later version.
  17  */
  18
  19 #include <linux/err.h>
  20 #include <linux/i2c.h>
  21 #include <linux/module.h>
  22 #include <linux/delay.h>
  23 #include <linux/sysfs.h>
  24 #include <linux/of.h>
  25
  26 #include <linux/iio/iio.h>
  27 #include <linux/iio/sysfs.h>
  28
  29 /* Masks */
  30 #define MCP3422_CHANNEL_MASK    0x60
  31 #define MCP3422_PGA_MASK        0x03
  32 #define MCP3422_SRATE_MASK      0x0C
  33 #define MCP3422_SRATE_240       0x0
  34 #define MCP3422_SRATE_60        0x1
  35 #define MCP3422_SRATE_15        0x2
  36 #define MCP3422_SRATE_3 0x3
  37 #define MCP3422_PGA_1   0
  38 #define MCP3422_PGA_2   1
  39 #define MCP3422_PGA_4   2
  40 #define MCP3422_PGA_8   3
  41 #define MCP3422_CONT_SAMPLING   0x10
  42
  43 #define MCP3422_CHANNEL(config) (((config) & MCP3422_CHANNEL_MASK) >> 5)
  44 #define MCP3422_PGA(config)     ((config) & MCP3422_PGA_MASK)
  45 #define MCP3422_SAMPLE_RATE(config)     (((config) & MCP3422_SRATE_MASK) >> 2)
  46
  47 #define MCP3422_CHANNEL_VALUE(value) (((value) << 5) & MCP3422_CHANNEL_MASK)
  48 #define MCP3422_PGA_VALUE(value) ((value) & MCP3422_PGA_MASK)
  49 #define MCP3422_SAMPLE_RATE_VALUE(value) ((value << 2) & MCP3422_SRATE_MASK)
  50
  51 #define MCP3422_CHAN(_index) \
  52         { \
  53                 .type = IIO_VOLTAGE, \
  54                 .indexed = 1, \
  55                 .channel = _index, \
  56                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) \
  57                                 | BIT(IIO_CHAN_INFO_SCALE), \
  58                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ), \
  59         }
  60
  61 /* LSB is in nV to eliminate floating point */
  62 static const u32 rates_to_lsb[] = {1000000, 250000, 62500, 15625};
  63
  64 /*
  65  *  scales calculated as:
  66  *  rates_to_lsb[sample_rate] / (1 << pga);
  67  *  pga is 1 for 0, 2
  68  */
  69
  70 static const int mcp3422_scales[4][4] = {
  71         { 1000000, 250000, 62500, 15625 },
  72         { 500000 , 125000, 31250, 7812 },
  73         { 250000 , 62500 , 15625, 3906 },
  74         { 125000 , 31250 , 7812 , 1953 } };
  75
  76 /* Constant msleep times for data acquisitions */
  77 static const int mcp3422_read_times[4] = {
  78         [MCP3422_SRATE_240] = 1000 / 240,
  79         [MCP3422_SRATE_60] = 1000 / 60,
  80         [MCP3422_SRATE_15] = 1000 / 15,
  81         [MCP3422_SRATE_3] = 1000 / 3 };
  82
  83 /* sample rates to integer conversion table */
  84 static const int mcp3422_sample_rates[4] = {
  85         [MCP3422_SRATE_240] = 240,
  86         [MCP3422_SRATE_60] = 60,
  87         [MCP3422_SRATE_15] = 15,
  88         [MCP3422_SRATE_3] = 3 };
  89
  90 /* sample rates to sign extension table */
  91 static const int mcp3422_sign_extend[4] = {
  92         [MCP3422_SRATE_240] = 11,
  93         [MCP3422_SRATE_60] = 13,
  94         [MCP3422_SRATE_15] = 15,
  95         [MCP3422_SRATE_3] = 17 };
  96
  97 /* Client data (each client gets its own) */
  98 struct mcp3422 {
  99         struct i2c_client *i2c;
 100         u8 id;
 101         u8 config;
 102         u8 pga[4];
 103         struct mutex lock;
 104 };
 105
 106 static int mcp3422_update_config(struct mcp3422 *adc, u8 newconfig)
 107 {
 108         int ret;
 109
 110         mutex_lock(&adc->lock);
 111
 112         ret = i2c_master_send(adc->i2c, &newconfig, 1);
 113         if (ret > 0) {
 114                 adc->config = newconfig;
 115                 ret = 0;
 116         }
 117
 118         mutex_unlock(&adc->lock);
 119
 120         return ret;
 121 }
 122
 123 static int mcp3422_read(struct mcp3422 *adc, int *value, u8 *config)
 124 {
 125         int ret = 0;
 126         u8 sample_rate = MCP3422_SAMPLE_RATE(adc->config);
 127         u8 buf[4] = {0, 0, 0, 0};
 128         u32 temp;
 129
 130         if (sample_rate == MCP3422_SRATE_3) {
 131                 ret = i2c_master_recv(adc->i2c, buf, 4);
 132                 temp = buf[0] << 16 | buf[1] << 8 | buf[2];
 133                 *config = buf[3];
 134         } else {
 135                 ret = i2c_master_recv(adc->i2c, buf, 3);
 136                 temp = buf[0] << 8 | buf[1];
 137                 *config = buf[2];
 138         }
 139
 140         *value = sign_extend32(temp, mcp3422_sign_extend[sample_rate]);
 141
 142         return ret;
 143 }
 144
 145 static int mcp3422_read_channel(struct mcp3422 *adc,
 146                                 struct iio_chan_spec const *channel, int *value)
 147 {
 148         int ret;
 149         u8 config;
 150         u8 req_channel = channel->channel;
 151
 152         if (req_channel != MCP3422_CHANNEL(adc->config)) {
 153                 config = adc->config;
 154                 config &= ~MCP3422_CHANNEL_MASK;
 155                 config |= MCP3422_CHANNEL_VALUE(req_channel);
 156                 config &= ~MCP3422_PGA_MASK;
 157                 config |= MCP3422_PGA_VALUE(adc->pga[req_channel]);
 158                 ret = mcp3422_update_config(adc, config);
 159                 if (ret < 0)
 160                         return ret;
 161                 msleep(mcp3422_read_times[MCP3422_SAMPLE_RATE(adc->config)]);
 162         }
 163
 164         return mcp3422_read(adc, value, &config);
 165 }
 166
 167 static int mcp3422_read_raw(struct iio_dev *iio,
 168                         struct iio_chan_spec const *channel, int *val1,
 169                         int *val2, long mask)
 170 {
 171         struct mcp3422 *adc = iio_priv(iio);
 172         int err;
 173
 174         u8 sample_rate = MCP3422_SAMPLE_RATE(adc->config);
 175         u8 pga           = MCP3422_PGA(adc->config);
 176
 177         switch (mask) {
 178         case IIO_CHAN_INFO_RAW:
 179                 err = mcp3422_read_channel(adc, channel, val1);
 180                 if (err < 0)
 181                         return -EINVAL;
 182                 return IIO_VAL_INT;
 183
 184         case IIO_CHAN_INFO_SCALE:
 185
 186                 *val1 = 0;
 187                 *val2 = mcp3422_scales[sample_rate][pga];
 188                 return IIO_VAL_INT_PLUS_NANO;
 189
 190         case IIO_CHAN_INFO_SAMP_FREQ:
 191                 *val1 = mcp3422_sample_rates[MCP3422_SAMPLE_RATE(adc->config)];
 192                 return IIO_VAL_INT;
 193
 194         default:
 195                 break;
 196         }
 197
 198         return -EINVAL;
 199 }
 200
 201 static int mcp3422_write_raw(struct iio_dev *iio,
 202                         struct iio_chan_spec const *channel, int val1,
 203                         int val2, long mask)
 204 {
 205         struct mcp3422 *adc = iio_priv(iio);
 206         u8 temp;
 207         u8 config = adc->config;
 208         u8 req_channel = channel->channel;
 209         u8 sample_rate = MCP3422_SAMPLE_RATE(config);
 210         u8 i;
 211
 212         switch (mask) {
 213         case IIO_CHAN_INFO_SCALE:
 214                 if (val1 != 0)
 215                         return -EINVAL;
 216
 217                 for (i = 0; i < ARRAY_SIZE(mcp3422_scales[0]); i++) {
 218                         if (val2 == mcp3422_scales[sample_rate][i]) {
 219                                 adc->pga[req_channel] = i;
 220
 221                                 config &= ~MCP3422_CHANNEL_MASK;
 222                                 config |= MCP3422_CHANNEL_VALUE(req_channel);
 223                                 config &= ~MCP3422_PGA_MASK;
 224                                 config |= MCP3422_PGA_VALUE(adc->pga[req_channel]);
 225
 226                                 return mcp3422_update_config(adc, config);
 227                         }
 228                 }
 229                 return -EINVAL;
 230
 231         case IIO_CHAN_INFO_SAMP_FREQ:
 232                 switch (val1) {
 233                 case 240:
 234                         temp = MCP3422_SRATE_240;
 235                         break;
 236                 case 60:
 237                         temp = MCP3422_SRATE_60;
 238                         break;
 239                 case 15:
 240                         temp = MCP3422_SRATE_15;
 241                         break;
 242                 case 3:
 243                         if (adc->id > 4)
 244                                 return -EINVAL;
 245                         temp = MCP3422_SRATE_3;
 246                         break;
 247                 default:
 248                         return -EINVAL;
 249                 }
 250
 251                 config &= ~MCP3422_CHANNEL_MASK;
 252                 config |= MCP3422_CHANNEL_VALUE(req_channel);
 253                 config &= ~MCP3422_SRATE_MASK;
 254                 config |= MCP3422_SAMPLE_RATE_VALUE(temp);
 255
 256                 return mcp3422_update_config(adc, config);
 257
 258         default:
 259                 break;
 260         }
 261
 262         return -EINVAL;
 263 }
 264
 265 static int mcp3422_write_raw_get_fmt(struct iio_dev *indio_dev,
 266                 struct iio_chan_spec const *chan, long mask)
 267 {
 268         switch (mask) {
 269         case IIO_CHAN_INFO_SCALE:
 270                 return IIO_VAL_INT_PLUS_NANO;
 271         case IIO_CHAN_INFO_SAMP_FREQ:
 272                 return IIO_VAL_INT_PLUS_MICRO;
 273         default:
 274                 return -EINVAL;
 275         }
 276 }
 277
 278 static ssize_t mcp3422_show_samp_freqs(struct device *dev,
 279                 struct device_attribute *attr, char *buf)
 280 {
 281         struct mcp3422 *adc = iio_priv(dev_to_iio_dev(dev));
 282
 283         if (adc->id > 4)
 284                 return sprintf(buf, "240 60 15\n");
 285
 286         return sprintf(buf, "240 60 15 3\n");
 287 }
 288
 289 static ssize_t mcp3422_show_scales(struct device *dev,
 290                 struct device_attribute *attr, char *buf)
 291 {
 292         struct mcp3422 *adc = iio_priv(dev_to_iio_dev(dev));
 293         u8 sample_rate = MCP3422_SAMPLE_RATE(adc->config);
 294
 295         return sprintf(buf, "0.%09u 0.%09u 0.%09u 0.%09u\n",
 296                 mcp3422_scales[sample_rate][0],
 297                 mcp3422_scales[sample_rate][1],
 298                 mcp3422_scales[sample_rate][2],
 299                 mcp3422_scales[sample_rate][3]);
 300 }
 301
 302 static IIO_DEVICE_ATTR(sampling_frequency_available, S_IRUGO,
 303                 mcp3422_show_samp_freqs, NULL, 0);
 304 static IIO_DEVICE_ATTR(in_voltage_scale_available, S_IRUGO,
 305                 mcp3422_show_scales, NULL, 0);
 306
 307 static struct attribute *mcp3422_attributes[] = {
 308         &iio_dev_attr_sampling_frequency_available.dev_attr.attr,
 309         &iio_dev_attr_in_voltage_scale_available.dev_attr.attr,
 310         NULL,
 311 };
 312
 313 static const struct attribute_group mcp3422_attribute_group = {
 314         .attrs = mcp3422_attributes,
 315 };
 316
 317 static const struct iio_chan_spec mcp3422_channels[] = {
 318         MCP3422_CHAN(0),
 319         MCP3422_CHAN(1),
 320 };
 321
 322 static const struct iio_chan_spec mcp3424_channels[] = {
 323         MCP3422_CHAN(0),
 324         MCP3422_CHAN(1),
 325         MCP3422_CHAN(2),
 326         MCP3422_CHAN(3),
 327 };
 328
 329 static const struct iio_info mcp3422_info = {
 330         .read_raw = mcp3422_read_raw,
 331         .write_raw = mcp3422_write_raw,
 332         .write_raw_get_fmt = mcp3422_write_raw_get_fmt,
 333         .attrs = &mcp3422_attribute_group,
 334         .driver_module = THIS_MODULE,
 335 };
 336
 337 static int mcp3422_probe(struct i2c_client *client,
 338                          const struct i2c_device_id *id)
 339 {
 340         struct iio_dev *indio_dev;
 341         struct mcp3422 *adc;
 342         int err;
 343         u8 config;
 344
 345         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 346                 return -ENODEV;
 347
 348         indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*adc));
 349         if (!indio_dev)
 350                 return -ENOMEM;
 351
 352         adc = iio_priv(indio_dev);
 353         adc->i2c = client;
 354         adc->id = (u8)(id->driver_data);
 355
 356         mutex_init(&adc->lock);
 357
 358         indio_dev->dev.parent = &client->dev;
 359         indio_dev->name = dev_name(&client->dev);
 360         indio_dev->modes = INDIO_DIRECT_MODE;
 361         indio_dev->info = &mcp3422_info;
 362
 363         switch (adc->id) {
 364         case 2:
 365         case 3:
 366         case 6:
 367         case 7:
 368                 indio_dev->channels = mcp3422_channels;
 369                 indio_dev->num_channels = ARRAY_SIZE(mcp3422_channels);
 370                 break;
 371         case 4:
 372         case 8:
 373                 indio_dev->channels = mcp3424_channels;
 374                 indio_dev->num_channels = ARRAY_SIZE(mcp3424_channels);
 375                 break;
 376         }
 377
 378         /* meaningful default configuration */
 379         config = (MCP3422_CONT_SAMPLING
 380                 | MCP3422_CHANNEL_VALUE(1)
 381                 | MCP3422_PGA_VALUE(MCP3422_PGA_1)
 382                 | MCP3422_SAMPLE_RATE_VALUE(MCP3422_SRATE_240));
 383         mcp3422_update_config(adc, config);
 384
 385         err = devm_iio_device_register(&client->dev, indio_dev);
 386         if (err < 0)
 387                 return err;
 388
 389         i2c_set_clientdata(client, indio_dev);
 390
 391         return 0;
 392 }
 393
 394 static const struct i2c_device_id mcp3422_id[] = {
 395         { "mcp3422", 2 },
 396         { "mcp3423", 3 },
 397         { "mcp3424", 4 },
 398         { "mcp3426", 6 },
 399         { "mcp3427", 7 },
 400         { "mcp3428", 8 },
 401         { }
 402 };
 403 MODULE_DEVICE_TABLE(i2c, mcp3422_id);
 404
 405 #ifdef CONFIG_OF
 406 static const struct of_device_id mcp3422_of_match[] = {
 407         { .compatible = "mcp3422" },
 408         { }
 409 };
 410 MODULE_DEVICE_TABLE(of, mcp3422_of_match);
 411 #endif
 412
 413 static struct i2c_driver mcp3422_driver = {
 414         .driver = {
 415                 .name = "mcp3422",
 416                 .owner = THIS_MODULE,
 417                 .of_match_table = of_match_ptr(mcp3422_of_match),
 418         },
 419         .probe = mcp3422_probe,
 420         .id_table = mcp3422_id,
 421 };
 422 module_i2c_driver(mcp3422_driver);
 423
 424 MODULE_AUTHOR("Angelo Compagnucci <angelo.compagnucci@gmail.com>");
 425 MODULE_DESCRIPTION("Microchip mcp3422/3/4/6/7/8 driver");
 426 MODULE_LICENSE("GPL v2");