drivers/iio/adc/mcp3422.c

   1 /*
   2  * mcp3422.c - driver for the Microchip mcp3421/2/3/4/5/6/7/8 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  *            http://ww1.microchip.com/downloads/en/DeviceDoc/22072b.pdf
  10  *
  11  * This driver exports the value of analog input voltage to sysfs, the
  12  * voltage unit is nV.
  13  *
  14  * This program is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License as published by
  16  * the Free Software Foundation; either version 2 of the License, or
  17  * (at your option) any later version.
  18  */
  19
  20 #include <linux/err.h>
  21 #include <linux/i2c.h>
  22 #include <linux/module.h>
  23 #include <linux/delay.h>
  24 #include <linux/sysfs.h>
  25 #include <linux/of.h>
  26
  27 #include <linux/iio/iio.h>
  28 #include <linux/iio/sysfs.h>
  29
  30 /* Masks */
  31 #define MCP3422_CHANNEL_MASK    0x60
  32 #define MCP3422_PGA_MASK        0x03
  33 #define MCP3422_SRATE_MASK      0x0C
  34 #define MCP3422_SRATE_240       0x0
  35 #define MCP3422_SRATE_60        0x1
  36 #define MCP3422_SRATE_15        0x2
  37 #define MCP3422_SRATE_3 0x3
  38 #define MCP3422_PGA_1   0
  39 #define MCP3422_PGA_2   1
  40 #define MCP3422_PGA_4   2
  41 #define MCP3422_PGA_8   3
  42 #define MCP3422_CONT_SAMPLING   0x10
  43
  44 #define MCP3422_CHANNEL(config) (((config) & MCP3422_CHANNEL_MASK) >> 5)
  45 #define MCP3422_PGA(config)     ((config) & MCP3422_PGA_MASK)
  46 #define MCP3422_SAMPLE_RATE(config)     (((config) & MCP3422_SRATE_MASK) >> 2)
  47
  48 #define MCP3422_CHANNEL_VALUE(value) (((value) << 5) & MCP3422_CHANNEL_MASK)
  49 #define MCP3422_PGA_VALUE(value) ((value) & MCP3422_PGA_MASK)
  50 #define MCP3422_SAMPLE_RATE_VALUE(value) ((value << 2) & MCP3422_SRATE_MASK)
  51
  52 #define MCP3422_CHAN(_index) \
  53         { \
  54                 .type = IIO_VOLTAGE, \
  55                 .indexed = 1, \
  56                 .channel = _index, \
  57                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) \
  58                                 | BIT(IIO_CHAN_INFO_SCALE), \
  59                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ), \
  60         }
  61
  62 static const int mcp3422_scales[4][4] = {
  63         { 1000000, 500000, 250000, 125000 },
  64         { 250000,  125000, 62500,  31250  },
  65         { 62500,   31250,  15625,  7812   },
  66         { 15625,   7812,   3906,   1953   } };
  67
  68 /* Constant msleep times for data acquisitions */
  69 static const int mcp3422_read_times[4] = {
  70         [MCP3422_SRATE_240] = 1000 / 240,
  71         [MCP3422_SRATE_60] = 1000 / 60,
  72         [MCP3422_SRATE_15] = 1000 / 15,
  73         [MCP3422_SRATE_3] = 1000 / 3 };
  74
  75 /* sample rates to integer conversion table */
  76 static const int mcp3422_sample_rates[4] = {
  77         [MCP3422_SRATE_240] = 240,
  78         [MCP3422_SRATE_60] = 60,
  79         [MCP3422_SRATE_15] = 15,
  80         [MCP3422_SRATE_3] = 3 };
  81
  82 /* sample rates to sign extension table */
  83 static const int mcp3422_sign_extend[4] = {
  84         [MCP3422_SRATE_240] = 11,
  85         [MCP3422_SRATE_60] = 13,
  86         [MCP3422_SRATE_15] = 15,
  87         [MCP3422_SRATE_3] = 17 };
  88
  89 /* Client data (each client gets its own) */
  90 struct mcp3422 {
  91         struct i2c_client *i2c;
  92         u8 id;
  93         u8 config;
  94         u8 pga[4];
  95         struct mutex lock;
  96 };
  97
  98 static int mcp3422_update_config(struct mcp3422 *adc, u8 newconfig)
  99 {
 100         int ret;
 101
 102         mutex_lock(&adc->lock);
 103
 104         ret = i2c_master_send(adc->i2c, &newconfig, 1);
 105         if (ret > 0) {
 106                 adc->config = newconfig;
 107                 ret = 0;
 108         }
 109
 110         mutex_unlock(&adc->lock);
 111
 112         return ret;
 113 }
 114
 115 static int mcp3422_read(struct mcp3422 *adc, int *value, u8 *config)
 116 {
 117         int ret = 0;
 118         u8 sample_rate = MCP3422_SAMPLE_RATE(adc->config);
 119         u8 buf[4] = {0, 0, 0, 0};
 120         u32 temp;
 121
 122         if (sample_rate == MCP3422_SRATE_3) {
 123                 ret = i2c_master_recv(adc->i2c, buf, 4);
 124                 temp = buf[0] << 16 | buf[1] << 8 | buf[2];
 125                 *config = buf[3];
 126         } else {
 127                 ret = i2c_master_recv(adc->i2c, buf, 3);
 128                 temp = buf[0] << 8 | buf[1];
 129                 *config = buf[2];
 130         }
 131
 132         *value = sign_extend32(temp, mcp3422_sign_extend[sample_rate]);
 133
 134         return ret;
 135 }
 136
 137 static int mcp3422_read_channel(struct mcp3422 *adc,
 138                                 struct iio_chan_spec const *channel, int *value)
 139 {
 140         int ret;
 141         u8 config;
 142         u8 req_channel = channel->channel;
 143
 144         if (req_channel != MCP3422_CHANNEL(adc->config)) {
 145                 config = adc->config;
 146                 config &= ~MCP3422_CHANNEL_MASK;
 147                 config |= MCP3422_CHANNEL_VALUE(req_channel);
 148                 config &= ~MCP3422_PGA_MASK;
 149                 config |= MCP3422_PGA_VALUE(adc->pga[req_channel]);
 150                 ret = mcp3422_update_config(adc, config);
 151                 if (ret < 0)
 152                         return ret;
 153                 msleep(mcp3422_read_times[MCP3422_SAMPLE_RATE(adc->config)]);
 154         }
 155
 156         return mcp3422_read(adc, value, &config);
 157 }
 158
 159 static int mcp3422_read_raw(struct iio_dev *iio,
 160                         struct iio_chan_spec const *channel, int *val1,
 161                         int *val2, long mask)
 162 {
 163         struct mcp3422 *adc = iio_priv(iio);
 164         int err;
 165
 166         u8 sample_rate = MCP3422_SAMPLE_RATE(adc->config);
 167         u8 pga           = MCP3422_PGA(adc->config);
 168
 169         switch (mask) {
 170         case IIO_CHAN_INFO_RAW:
 171                 err = mcp3422_read_channel(adc, channel, val1);
 172                 if (err < 0)
 173                         return -EINVAL;
 174                 return IIO_VAL_INT;
 175
 176         case IIO_CHAN_INFO_SCALE:
 177
 178                 *val1 = 0;
 179                 *val2 = mcp3422_scales[sample_rate][pga];
 180                 return IIO_VAL_INT_PLUS_NANO;
 181
 182         case IIO_CHAN_INFO_SAMP_FREQ:
 183                 *val1 = mcp3422_sample_rates[MCP3422_SAMPLE_RATE(adc->config)];
 184                 return IIO_VAL_INT;
 185
 186         default:
 187                 break;
 188         }
 189
 190         return -EINVAL;
 191 }
 192
 193 static int mcp3422_write_raw(struct iio_dev *iio,
 194                         struct iio_chan_spec const *channel, int val1,
 195                         int val2, long mask)
 196 {
 197         struct mcp3422 *adc = iio_priv(iio);
 198         u8 temp;
 199         u8 config = adc->config;
 200         u8 req_channel = channel->channel;
 201         u8 sample_rate = MCP3422_SAMPLE_RATE(config);
 202         u8 i;
 203
 204         switch (mask) {
 205         case IIO_CHAN_INFO_SCALE:
 206                 if (val1 != 0)
 207                         return -EINVAL;
 208
 209                 for (i = 0; i < ARRAY_SIZE(mcp3422_scales[0]); i++) {
 210                         if (val2 == mcp3422_scales[sample_rate][i]) {
 211                                 adc->pga[req_channel] = i;
 212
 213                                 config &= ~MCP3422_CHANNEL_MASK;
 214                                 config |= MCP3422_CHANNEL_VALUE(req_channel);
 215                                 config &= ~MCP3422_PGA_MASK;
 216                                 config |= MCP3422_PGA_VALUE(adc->pga[req_channel]);
 217
 218                                 return mcp3422_update_config(adc, config);
 219                         }
 220                 }
 221                 return -EINVAL;
 222
 223         case IIO_CHAN_INFO_SAMP_FREQ:
 224                 switch (val1) {
 225                 case 240:
 226                         temp = MCP3422_SRATE_240;
 227                         break;
 228                 case 60:
 229                         temp = MCP3422_SRATE_60;
 230                         break;
 231                 case 15:
 232                         temp = MCP3422_SRATE_15;
 233                         break;
 234                 case 3:
 235                         if (adc->id > 4)
 236                                 return -EINVAL;
 237                         temp = MCP3422_SRATE_3;
 238                         break;
 239                 default:
 240                         return -EINVAL;
 241                 }
 242
 243                 config &= ~MCP3422_CHANNEL_MASK;
 244                 config |= MCP3422_CHANNEL_VALUE(req_channel);
 245                 config &= ~MCP3422_SRATE_MASK;
 246                 config |= MCP3422_SAMPLE_RATE_VALUE(temp);
 247
 248                 return mcp3422_update_config(adc, config);
 249
 250         default:
 251                 break;
 252         }
 253
 254         return -EINVAL;
 255 }
 256
 257 static int mcp3422_write_raw_get_fmt(struct iio_dev *indio_dev,
 258                 struct iio_chan_spec const *chan, long mask)
 259 {
 260         switch (mask) {
 261         case IIO_CHAN_INFO_SCALE:
 262                 return IIO_VAL_INT_PLUS_NANO;
 263         case IIO_CHAN_INFO_SAMP_FREQ:
 264                 return IIO_VAL_INT_PLUS_MICRO;
 265         default:
 266                 return -EINVAL;
 267         }
 268 }
 269
 270 static ssize_t mcp3422_show_samp_freqs(struct device *dev,
 271                 struct device_attribute *attr, char *buf)
 272 {
 273         struct mcp3422 *adc = iio_priv(dev_to_iio_dev(dev));
 274
 275         if (adc->id > 4)
 276                 return sprintf(buf, "240 60 15\n");
 277
 278         return sprintf(buf, "240 60 15 3\n");
 279 }
 280
 281 static ssize_t mcp3422_show_scales(struct device *dev,
 282                 struct device_attribute *attr, char *buf)
 283 {
 284         struct mcp3422 *adc = iio_priv(dev_to_iio_dev(dev));
 285         u8 sample_rate = MCP3422_SAMPLE_RATE(adc->config);
 286
 287         return sprintf(buf, "0.%09u 0.%09u 0.%09u 0.%09u\n",
 288                 mcp3422_scales[sample_rate][0],
 289                 mcp3422_scales[sample_rate][1],
 290                 mcp3422_scales[sample_rate][2],
 291                 mcp3422_scales[sample_rate][3]);
 292 }
 293
 294 static IIO_DEVICE_ATTR(sampling_frequency_available, S_IRUGO,
 295                 mcp3422_show_samp_freqs, NULL, 0);
 296 static IIO_DEVICE_ATTR(in_voltage_scale_available, S_IRUGO,
 297                 mcp3422_show_scales, NULL, 0);
 298
 299 static struct attribute *mcp3422_attributes[] = {
 300         &iio_dev_attr_sampling_frequency_available.dev_attr.attr,
 301         &iio_dev_attr_in_voltage_scale_available.dev_attr.attr,
 302         NULL,
 303 };
 304
 305 static const struct attribute_group mcp3422_attribute_group = {
 306         .attrs = mcp3422_attributes,
 307 };
 308
 309 static const struct iio_chan_spec mcp3421_channels[] = {
 310         MCP3422_CHAN(0),
 311 };
 312
 313 static const struct iio_chan_spec mcp3422_channels[] = {
 314         MCP3422_CHAN(0),
 315         MCP3422_CHAN(1),
 316 };
 317
 318 static const struct iio_chan_spec mcp3424_channels[] = {
 319         MCP3422_CHAN(0),
 320         MCP3422_CHAN(1),
 321         MCP3422_CHAN(2),
 322         MCP3422_CHAN(3),
 323 };
 324
 325 static const struct iio_info mcp3422_info = {
 326         .read_raw = mcp3422_read_raw,
 327         .write_raw = mcp3422_write_raw,
 328         .write_raw_get_fmt = mcp3422_write_raw_get_fmt,
 329         .attrs = &mcp3422_attribute_group,
 330         .driver_module = THIS_MODULE,
 331 };
 332
 333 static int mcp3422_probe(struct i2c_client *client,
 334                          const struct i2c_device_id *id)
 335 {
 336         struct iio_dev *indio_dev;
 337         struct mcp3422 *adc;
 338         int err;
 339         u8 config;
 340
 341         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 342                 return -EOPNOTSUPP;
 343
 344         indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*adc));
 345         if (!indio_dev)
 346                 return -ENOMEM;
 347
 348         adc = iio_priv(indio_dev);
 349         adc->i2c = client;
 350         adc->id = (u8)(id->driver_data);
 351
 352         mutex_init(&adc->lock);
 353
 354         indio_dev->dev.parent = &client->dev;
 355         indio_dev->dev.of_node = client->dev.of_node;
 356         indio_dev->name = dev_name(&client->dev);
 357         indio_dev->modes = INDIO_DIRECT_MODE;
 358         indio_dev->info = &mcp3422_info;
 359
 360         switch (adc->id) {
 361         case 1:
 362         case 5:
 363                 indio_dev->channels = mcp3421_channels;
 364                 indio_dev->num_channels = ARRAY_SIZE(mcp3421_channels);
 365                 break;
 366         case 2:
 367         case 3:
 368         case 6:
 369         case 7:
 370                 indio_dev->channels = mcp3422_channels;
 371                 indio_dev->num_channels = ARRAY_SIZE(mcp3422_channels);
 372                 break;
 373         case 4:
 374         case 8:
 375                 indio_dev->channels = mcp3424_channels;
 376                 indio_dev->num_channels = ARRAY_SIZE(mcp3424_channels);
 377                 break;
 378         }
 379
 380         /* meaningful default configuration */
 381         config = (MCP3422_CONT_SAMPLING
 382                 | MCP3422_CHANNEL_VALUE(1)
 383                 | MCP3422_PGA_VALUE(MCP3422_PGA_1)
 384                 | MCP3422_SAMPLE_RATE_VALUE(MCP3422_SRATE_240));
 385         mcp3422_update_config(adc, config);
 386
 387         err = devm_iio_device_register(&client->dev, indio_dev);
 388         if (err < 0)
 389                 return err;
 390
 391         i2c_set_clientdata(client, indio_dev);
 392
 393         return 0;
 394 }
 395
 396 static const struct i2c_device_id mcp3422_id[] = {
 397         { "mcp3421", 1 },
 398         { "mcp3422", 2 },
 399         { "mcp3423", 3 },
 400         { "mcp3424", 4 },
 401         { "mcp3425", 5 },
 402         { "mcp3426", 6 },
 403         { "mcp3427", 7 },
 404         { "mcp3428", 8 },
 405         { }
 406 };
 407 MODULE_DEVICE_TABLE(i2c, mcp3422_id);
 408
 409 #ifdef CONFIG_OF
 410 static const struct of_device_id mcp3422_of_match[] = {
 411         { .compatible = "mcp3422" },
 412         { }
 413 };
 414 MODULE_DEVICE_TABLE(of, mcp3422_of_match);
 415 #endif
 416
 417 static struct i2c_driver mcp3422_driver = {
 418         .driver = {
 419                 .name = "mcp3422",
 420                 .of_match_table = of_match_ptr(mcp3422_of_match),
 421         },
 422         .probe = mcp3422_probe,
 423         .id_table = mcp3422_id,
 424 };
 425 module_i2c_driver(mcp3422_driver);
 426
 427 MODULE_AUTHOR("Angelo Compagnucci <angelo.compagnucci@gmail.com>");
 428 MODULE_DESCRIPTION("Microchip mcp3421/2/3/4/5/6/7/8 driver");
 429 MODULE_LICENSE("GPL v2");