drivers/iio/potentiostat/lmp91000.c

   1 /*
   2  * lmp91000.c - Support for Texas Instruments digital potentiostats
   3  *
   4  * Copyright (C) 2016 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  * TODO: bias voltage + polarity control, and multiple chip support
  17  */
  18
  19 #include <linux/module.h>
  20 #include <linux/i2c.h>
  21 #include <linux/delay.h>
  22 #include <linux/of.h>
  23 #include <linux/regmap.h>
  24 #include <linux/iio/iio.h>
  25 #include <linux/iio/buffer.h>
  26 #include <linux/iio/consumer.h>
  27 #include <linux/iio/trigger.h>
  28 #include <linux/iio/trigger_consumer.h>
  29 #include <linux/iio/triggered_buffer.h>
  30
  31 #define LMP91000_REG_LOCK               0x01
  32 #define LMP91000_REG_TIACN              0x10
  33 #define LMP91000_REG_TIACN_GAIN_SHIFT   2
  34
  35 #define LMP91000_REG_REFCN              0x11
  36 #define LMP91000_REG_REFCN_EXT_REF      0x20
  37 #define LMP91000_REG_REFCN_50_ZERO      0x80
  38
  39 #define LMP91000_REG_MODECN             0x12
  40 #define LMP91000_REG_MODECN_3LEAD       0x03
  41 #define LMP91000_REG_MODECN_TEMP        0x07
  42
  43 #define LMP91000_DRV_NAME       "lmp91000"
  44
  45 static const int lmp91000_tia_gain[] = { 0, 2750, 3500, 7000, 14000, 35000,
  46                                          120000, 350000 };
  47
  48 static const int lmp91000_rload[] = { 10, 33, 50, 100 };
  49
  50 #define LMP91000_TEMP_BASE      -40
  51
  52 static const u16 lmp91000_temp_lut[] = {
  53         1875, 1867, 1860, 1852, 1844, 1836, 1828, 1821, 1813, 1805,
  54         1797, 1789, 1782, 1774, 1766, 1758, 1750, 1742, 1734, 1727,
  55         1719, 1711, 1703, 1695, 1687, 1679, 1671, 1663, 1656, 1648,
  56         1640, 1632, 1624, 1616, 1608, 1600, 1592, 1584, 1576, 1568,
  57         1560, 1552, 1544, 1536, 1528, 1520, 1512, 1504, 1496, 1488,
  58         1480, 1472, 1464, 1456, 1448, 1440, 1432, 1424, 1415, 1407,
  59         1399, 1391, 1383, 1375, 1367, 1359, 1351, 1342, 1334, 1326,
  60         1318, 1310, 1302, 1293, 1285, 1277, 1269, 1261, 1253, 1244,
  61         1236, 1228, 1220, 1212, 1203, 1195, 1187, 1179, 1170, 1162,
  62         1154, 1146, 1137, 1129, 1121, 1112, 1104, 1096, 1087, 1079,
  63         1071, 1063, 1054, 1046, 1038, 1029, 1021, 1012, 1004,  996,
  64          987,  979,  971,  962,  954,  945,  937,  929,  920,  912,
  65          903,  895,  886,  878,  870,  861 };
  66
  67 static const struct regmap_config lmp91000_regmap_config = {
  68         .reg_bits = 8,
  69         .val_bits = 8,
  70 };
  71
  72 struct lmp91000_data {
  73         struct regmap *regmap;
  74         struct device *dev;
  75
  76         struct iio_trigger *trig;
  77         struct iio_cb_buffer *cb_buffer;
  78         struct iio_channel *adc_chan;
  79
  80         struct completion completion;
  81         u8 chan_select;
  82         /* 64-bit data + 64-bit naturally aligned timestamp */
  83         u32 buffer[4] __aligned(8);
  84 };
  85
  86 static const struct iio_chan_spec lmp91000_channels[] = {
  87         { /* chemical channel mV */
  88                 .type = IIO_VOLTAGE,
  89                 .channel = 0,
  90                 .address = LMP91000_REG_MODECN_3LEAD,
  91                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
  92                                       BIT(IIO_CHAN_INFO_OFFSET) |
  93                                       BIT(IIO_CHAN_INFO_SCALE),
  94                 .scan_index = 0,
  95                 .scan_type = {
  96                         .sign = 's',
  97                         .realbits = 32,
  98                         .storagebits = 32,
  99                 },
 100         },
 101         IIO_CHAN_SOFT_TIMESTAMP(1),
 102         { /* temperature channel mV */
 103                 .type = IIO_TEMP,
 104                 .channel = 1,
 105                 .address = LMP91000_REG_MODECN_TEMP,
 106                 .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
 107                 .scan_index = -1,
 108         },
 109 };
 110
 111 static int lmp91000_read(struct lmp91000_data *data, int channel, int *val)
 112 {
 113         int state, ret;
 114
 115         ret = regmap_read(data->regmap, LMP91000_REG_MODECN, &state);
 116         if (ret)
 117                 return -EINVAL;
 118
 119         ret = regmap_write(data->regmap, LMP91000_REG_MODECN, channel);
 120         if (ret)
 121                 return -EINVAL;
 122
 123         /* delay till first temperature reading is complete */
 124         if ((state != channel) && (channel == LMP91000_REG_MODECN_TEMP))
 125                 usleep_range(3000, 4000);
 126
 127         data->chan_select = channel != LMP91000_REG_MODECN_3LEAD;
 128
 129         iio_trigger_poll_chained(data->trig);
 130
 131         ret = wait_for_completion_timeout(&data->completion, HZ);
 132         reinit_completion(&data->completion);
 133
 134         if (!ret)
 135                 return -ETIMEDOUT;
 136
 137         *val = data->buffer[data->chan_select];
 138
 139         return 0;
 140 }
 141
 142 static irqreturn_t lmp91000_buffer_handler(int irq, void *private)
 143 {
 144         struct iio_poll_func *pf = private;
 145         struct iio_dev *indio_dev = pf->indio_dev;
 146         struct lmp91000_data *data = iio_priv(indio_dev);
 147         int ret, val;
 148
 149         memset(data->buffer, 0, sizeof(data->buffer));
 150
 151         ret = lmp91000_read(data, LMP91000_REG_MODECN_3LEAD, &val);
 152         if (!ret) {
 153                 data->buffer[0] = val;
 154                 iio_push_to_buffers_with_timestamp(indio_dev, data->buffer,
 155                                                    iio_get_time_ns(indio_dev));
 156         }
 157
 158         iio_trigger_notify_done(indio_dev->trig);
 159
 160         return IRQ_HANDLED;
 161 }
 162
 163 static int lmp91000_read_raw(struct iio_dev *indio_dev,
 164                              struct iio_chan_spec const *chan,
 165                              int *val, int *val2, long mask)
 166 {
 167         struct lmp91000_data *data = iio_priv(indio_dev);
 168
 169         switch (mask) {
 170         case IIO_CHAN_INFO_RAW:
 171         case IIO_CHAN_INFO_PROCESSED: {
 172                 int ret = iio_channel_start_all_cb(data->cb_buffer);
 173
 174                 if (ret)
 175                         return ret;
 176
 177                 ret = lmp91000_read(data, chan->address, val);
 178
 179                 iio_channel_stop_all_cb(data->cb_buffer);
 180
 181                 if (ret)
 182                         return ret;
 183
 184                 if (mask == IIO_CHAN_INFO_PROCESSED) {
 185                         int tmp, i;
 186
 187                         ret = iio_convert_raw_to_processed(data->adc_chan,
 188                                                            *val, &tmp, 1);
 189                         if (ret)
 190                                 return ret;
 191
 192                         for (i = 0; i < ARRAY_SIZE(lmp91000_temp_lut); i++)
 193                                 if (lmp91000_temp_lut[i] < tmp)
 194                                         break;
 195
 196                         *val = (LMP91000_TEMP_BASE + i) * 1000;
 197                 }
 198                 return IIO_VAL_INT;
 199         }
 200         case IIO_CHAN_INFO_OFFSET:
 201                 return iio_read_channel_offset(data->adc_chan, val, val2);
 202         case IIO_CHAN_INFO_SCALE:
 203                 return iio_read_channel_scale(data->adc_chan, val, val2);
 204         }
 205
 206         return -EINVAL;
 207 }
 208
 209 static const struct iio_info lmp91000_info = {
 210         .driver_module = THIS_MODULE,
 211         .read_raw = lmp91000_read_raw,
 212 };
 213
 214 static int lmp91000_read_config(struct lmp91000_data *data)
 215 {
 216         struct device *dev = data->dev;
 217         struct device_node *np = dev->of_node;
 218         unsigned int reg, val;
 219         int i, ret;
 220
 221         ret = of_property_read_u32(np, "ti,tia-gain-ohm", &val);
 222         if (ret) {
 223                 if (of_property_read_bool(np, "ti,external-tia-resistor"))
 224                         val = 0;
 225                 else {
 226                         dev_err(dev, "no ti,tia-gain-ohm defined");
 227                         return ret;
 228                 }
 229         }
 230
 231         ret = -EINVAL;
 232         for (i = 0; i < ARRAY_SIZE(lmp91000_tia_gain); i++) {
 233                 if (lmp91000_tia_gain[i] == val) {
 234                         reg = i << LMP91000_REG_TIACN_GAIN_SHIFT;
 235                         ret = 0;
 236                         break;
 237                 }
 238         }
 239
 240         if (ret) {
 241                 dev_err(dev, "invalid ti,tia-gain-ohm %d\n", val);
 242                 return ret;
 243         }
 244
 245         ret = of_property_read_u32(np, "ti,rload-ohm", &val);
 246         if (ret) {
 247                 val = 100;
 248                 dev_info(dev, "no ti,rload-ohm defined, default to %d\n", val);
 249         }
 250
 251         ret = -EINVAL;
 252         for (i = 0; i < ARRAY_SIZE(lmp91000_rload); i++) {
 253                 if (lmp91000_rload[i] == val) {
 254                         reg |= i;
 255                         ret = 0;
 256                         break;
 257                 }
 258         }
 259
 260         if (ret) {
 261                 dev_err(dev, "invalid ti,rload-ohm %d\n", val);
 262                 return ret;
 263         }
 264
 265         regmap_write(data->regmap, LMP91000_REG_LOCK, 0);
 266         regmap_write(data->regmap, LMP91000_REG_TIACN, reg);
 267         regmap_write(data->regmap, LMP91000_REG_REFCN, LMP91000_REG_REFCN_EXT_REF
 268                                         | LMP91000_REG_REFCN_50_ZERO);
 269         regmap_write(data->regmap, LMP91000_REG_LOCK, 1);
 270
 271         return 0;
 272 }
 273
 274 static int lmp91000_buffer_cb(const void *val, void *private)
 275 {
 276         struct iio_dev *indio_dev = private;
 277         struct lmp91000_data *data = iio_priv(indio_dev);
 278
 279         data->buffer[data->chan_select] = *((int *)val);
 280         complete_all(&data->completion);
 281
 282         return 0;
 283 }
 284
 285 static const struct iio_trigger_ops lmp91000_trigger_ops = {
 286         .owner = THIS_MODULE,
 287 };
 288
 289
 290 static int lmp91000_buffer_preenable(struct iio_dev *indio_dev)
 291 {
 292         struct lmp91000_data *data = iio_priv(indio_dev);
 293
 294         return iio_channel_start_all_cb(data->cb_buffer);
 295 }
 296
 297 static int lmp91000_buffer_predisable(struct iio_dev *indio_dev)
 298 {
 299         struct lmp91000_data *data = iio_priv(indio_dev);
 300
 301         iio_channel_stop_all_cb(data->cb_buffer);
 302
 303         return 0;
 304 }
 305
 306 static const struct iio_buffer_setup_ops lmp91000_buffer_setup_ops = {
 307         .preenable = lmp91000_buffer_preenable,
 308         .postenable = iio_triggered_buffer_postenable,
 309         .predisable = lmp91000_buffer_predisable,
 310 };
 311
 312 static int lmp91000_probe(struct i2c_client *client,
 313                           const struct i2c_device_id *id)
 314 {
 315         struct device *dev = &client->dev;
 316         struct lmp91000_data *data;
 317         struct iio_dev *indio_dev;
 318         int ret;
 319
 320         indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
 321         if (!indio_dev)
 322                 return -ENOMEM;
 323
 324         indio_dev->info = &lmp91000_info;
 325         indio_dev->channels = lmp91000_channels;
 326         indio_dev->num_channels = ARRAY_SIZE(lmp91000_channels);
 327         indio_dev->name = LMP91000_DRV_NAME;
 328         indio_dev->dev.parent = &client->dev;
 329         indio_dev->modes = INDIO_DIRECT_MODE;
 330         i2c_set_clientdata(client, indio_dev);
 331
 332         data = iio_priv(indio_dev);
 333         data->dev = dev;
 334         data->regmap = devm_regmap_init_i2c(client, &lmp91000_regmap_config);
 335         if (IS_ERR(data->regmap)) {
 336                 dev_err(dev, "regmap initialization failed.\n");
 337                 return PTR_ERR(data->regmap);
 338         }
 339
 340         data->trig = devm_iio_trigger_alloc(data->dev, "%s-mux%d",
 341                                             indio_dev->name, indio_dev->id);
 342         if (!data->trig) {
 343                 dev_err(dev, "cannot allocate iio trigger.\n");
 344                 return -ENOMEM;
 345         }
 346
 347         data->trig->ops = &lmp91000_trigger_ops;
 348         data->trig->dev.parent = dev;
 349         init_completion(&data->completion);
 350
 351         ret = lmp91000_read_config(data);
 352         if (ret)
 353                 return ret;
 354
 355         ret = iio_trigger_set_immutable(iio_channel_cb_get_iio_dev(data->cb_buffer),
 356                                         data->trig);
 357         if (ret) {
 358                 dev_err(dev, "cannot set immutable trigger.\n");
 359                 return ret;
 360         }
 361
 362         ret = iio_trigger_register(data->trig);
 363         if (ret) {
 364                 dev_err(dev, "cannot register iio trigger.\n");
 365                 return ret;
 366         }
 367
 368         ret = iio_triggered_buffer_setup(indio_dev, NULL,
 369                                          &lmp91000_buffer_handler,
 370                                          &lmp91000_buffer_setup_ops);
 371         if (ret)
 372                 goto error_unreg_trigger;
 373
 374         data->cb_buffer = iio_channel_get_all_cb(dev, &lmp91000_buffer_cb,
 375                                                  indio_dev);
 376
 377         if (IS_ERR(data->cb_buffer)) {
 378                 if (PTR_ERR(data->cb_buffer) == -ENODEV)
 379                         ret = -EPROBE_DEFER;
 380                 else
 381                         ret = PTR_ERR(data->cb_buffer);
 382
 383                 goto error_unreg_buffer;
 384         }
 385
 386         data->adc_chan = iio_channel_cb_get_channels(data->cb_buffer);
 387
 388         ret = iio_device_register(indio_dev);
 389         if (ret)
 390                 goto error_unreg_cb_buffer;
 391
 392         return 0;
 393
 394 error_unreg_cb_buffer:
 395         iio_channel_release_all_cb(data->cb_buffer);
 396
 397 error_unreg_buffer:
 398         iio_triggered_buffer_cleanup(indio_dev);
 399
 400 error_unreg_trigger:
 401         iio_trigger_unregister(data->trig);
 402
 403         return ret;
 404 }
 405
 406 static int lmp91000_remove(struct i2c_client *client)
 407 {
 408         struct iio_dev *indio_dev = i2c_get_clientdata(client);
 409         struct lmp91000_data *data = iio_priv(indio_dev);
 410
 411         iio_device_unregister(indio_dev);
 412
 413         iio_channel_stop_all_cb(data->cb_buffer);
 414         iio_channel_release_all_cb(data->cb_buffer);
 415
 416         iio_triggered_buffer_cleanup(indio_dev);
 417         iio_trigger_unregister(data->trig);
 418
 419         return 0;
 420 }
 421
 422 static const struct of_device_id lmp91000_of_match[] = {
 423         { .compatible = "ti,lmp91000", },
 424         { },
 425 };
 426 MODULE_DEVICE_TABLE(of, lmp91000_of_match);
 427
 428 static const struct i2c_device_id lmp91000_id[] = {
 429         { "lmp91000", 0 },
 430         {}
 431 };
 432 MODULE_DEVICE_TABLE(i2c, lmp91000_id);
 433
 434 static struct i2c_driver lmp91000_driver = {
 435         .driver = {
 436                 .name = LMP91000_DRV_NAME,
 437                 .of_match_table = of_match_ptr(lmp91000_of_match),
 438         },
 439         .probe = lmp91000_probe,
 440         .remove = lmp91000_remove,
 441         .id_table = lmp91000_id,
 442 };
 443 module_i2c_driver(lmp91000_driver);
 444
 445 MODULE_AUTHOR("Matt Ranostay <mranostay@gmail.com>");
 446 MODULE_DESCRIPTION("LMP91000 digital potentiostat");
 447 MODULE_LICENSE("GPL");