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