linux/drivers/iio/adc/mcp3422.c
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   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
  62static 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 */
  69static 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 */
  76static 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 */
  83static 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) */
  90struct mcp3422 {
  91        struct i2c_client *i2c;
  92        u8 id;
  93        u8 config;
  94        u8 pga[4];
  95        struct mutex lock;
  96};
  97
  98static 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
 115static 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
 137static 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
 159static 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
 193static 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
 257static 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
 270static 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
 281static 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
 294static IIO_DEVICE_ATTR(sampling_frequency_available, S_IRUGO,
 295                mcp3422_show_samp_freqs, NULL, 0);
 296static IIO_DEVICE_ATTR(in_voltage_scale_available, S_IRUGO,
 297                mcp3422_show_scales, NULL, 0);
 298
 299static 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
 305static const struct attribute_group mcp3422_attribute_group = {
 306        .attrs = mcp3422_attributes,
 307};
 308
 309static const struct iio_chan_spec mcp3421_channels[] = {
 310        MCP3422_CHAN(0),
 311};
 312
 313static const struct iio_chan_spec mcp3422_channels[] = {
 314        MCP3422_CHAN(0),
 315        MCP3422_CHAN(1),
 316};
 317
 318static 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
 325static 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
 333static 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->name = dev_name(&client->dev);
 356        indio_dev->modes = INDIO_DIRECT_MODE;
 357        indio_dev->info = &mcp3422_info;
 358
 359        switch (adc->id) {
 360        case 1:
 361        case 5:
 362                indio_dev->channels = mcp3421_channels;
 363                indio_dev->num_channels = ARRAY_SIZE(mcp3421_channels);
 364                break;
 365        case 2:
 366        case 3:
 367        case 6:
 368        case 7:
 369                indio_dev->channels = mcp3422_channels;
 370                indio_dev->num_channels = ARRAY_SIZE(mcp3422_channels);
 371                break;
 372        case 4:
 373        case 8:
 374                indio_dev->channels = mcp3424_channels;
 375                indio_dev->num_channels = ARRAY_SIZE(mcp3424_channels);
 376                break;
 377        }
 378
 379        /* meaningful default configuration */
 380        config = (MCP3422_CONT_SAMPLING
 381                | MCP3422_CHANNEL_VALUE(1)
 382                | MCP3422_PGA_VALUE(MCP3422_PGA_1)
 383                | MCP3422_SAMPLE_RATE_VALUE(MCP3422_SRATE_240));
 384        mcp3422_update_config(adc, config);
 385
 386        err = devm_iio_device_register(&client->dev, indio_dev);
 387        if (err < 0)
 388                return err;
 389
 390        i2c_set_clientdata(client, indio_dev);
 391
 392        return 0;
 393}
 394
 395static const struct i2c_device_id mcp3422_id[] = {
 396        { "mcp3421", 1 },
 397        { "mcp3422", 2 },
 398        { "mcp3423", 3 },
 399        { "mcp3424", 4 },
 400        { "mcp3425", 5 },
 401        { "mcp3426", 6 },
 402        { "mcp3427", 7 },
 403        { "mcp3428", 8 },
 404        { }
 405};
 406MODULE_DEVICE_TABLE(i2c, mcp3422_id);
 407
 408#ifdef CONFIG_OF
 409static const struct of_device_id mcp3422_of_match[] = {
 410        { .compatible = "mcp3422" },
 411        { }
 412};
 413MODULE_DEVICE_TABLE(of, mcp3422_of_match);
 414#endif
 415
 416static struct i2c_driver mcp3422_driver = {
 417        .driver = {
 418                .name = "mcp3422",
 419                .of_match_table = of_match_ptr(mcp3422_of_match),
 420        },
 421        .probe = mcp3422_probe,
 422        .id_table = mcp3422_id,
 423};
 424module_i2c_driver(mcp3422_driver);
 425
 426MODULE_AUTHOR("Angelo Compagnucci <angelo.compagnucci@gmail.com>");
 427MODULE_DESCRIPTION("Microchip mcp3421/2/3/4/5/6/7/8 driver");
 428MODULE_LICENSE("GPL v2");
 429
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