drivers/iio/potentiostat/lmp91000.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * lmp91000.c - Support for Texas Instruments digital potentiostats
   4  *
   5  * Copyright (C) 2016, 2018
   6  * Author: Matt Ranostay <matt.ranostay@konsulko.com>
   7  *
   8  * TODO: bias voltage + polarity control, and multiple chip support
   9  */
  10
  11 #include <linux/module.h>
  12 #include <linux/i2c.h>
  13 #include <linux/delay.h>
  14 #include <linux/mod_devicetable.h>
  15 #include <linux/regmap.h>
  16 #include <linux/iio/iio.h>
  17 #include <linux/iio/buffer.h>
  18 #include <linux/iio/consumer.h>
  19 #include <linux/iio/trigger.h>
  20 #include <linux/iio/trigger_consumer.h>
  21 #include <linux/iio/triggered_buffer.h>
  22
  23 #define LMP91000_REG_LOCK               0x01
  24 #define LMP91000_REG_TIACN              0x10
  25 #define LMP91000_REG_TIACN_GAIN_SHIFT   2
  26
  27 #define LMP91000_REG_REFCN              0x11
  28 #define LMP91000_REG_REFCN_EXT_REF      0x20
  29 #define LMP91000_REG_REFCN_50_ZERO      0x80
  30
  31 #define LMP91000_REG_MODECN             0x12
  32 #define LMP91000_REG_MODECN_3LEAD       0x03
  33 #define LMP91000_REG_MODECN_TEMP        0x07
  34
  35 #define LMP91000_DRV_NAME       "lmp91000"
  36
  37 static const int lmp91000_tia_gain[] = { 0, 2750, 3500, 7000, 14000, 35000,
  38                                          120000, 350000 };
  39
  40 static const int lmp91000_rload[] = { 10, 33, 50, 100 };
  41
  42 #define LMP91000_TEMP_BASE      -40
  43
  44 static const u16 lmp91000_temp_lut[] = {
  45         1875, 1867, 1860, 1852, 1844, 1836, 1828, 1821, 1813, 1805,
  46         1797, 1789, 1782, 1774, 1766, 1758, 1750, 1742, 1734, 1727,
  47         1719, 1711, 1703, 1695, 1687, 1679, 1671, 1663, 1656, 1648,
  48         1640, 1632, 1624, 1616, 1608, 1600, 1592, 1584, 1576, 1568,
  49         1560, 1552, 1544, 1536, 1528, 1520, 1512, 1504, 1496, 1488,
  50         1480, 1472, 1464, 1456, 1448, 1440, 1432, 1424, 1415, 1407,
  51         1399, 1391, 1383, 1375, 1367, 1359, 1351, 1342, 1334, 1326,
  52         1318, 1310, 1302, 1293, 1285, 1277, 1269, 1261, 1253, 1244,
  53         1236, 1228, 1220, 1212, 1203, 1195, 1187, 1179, 1170, 1162,
  54         1154, 1146, 1137, 1129, 1121, 1112, 1104, 1096, 1087, 1079,
  55         1071, 1063, 1054, 1046, 1038, 1029, 1021, 1012, 1004,  996,
  56          987,  979,  971,  962,  954,  945,  937,  929,  920,  912,
  57          903,  895,  886,  878,  870,  861 };
  58
  59 static const struct regmap_config lmp91000_regmap_config = {
  60         .reg_bits = 8,
  61         .val_bits = 8,
  62 };
  63
  64 struct lmp91000_data {
  65         struct regmap *regmap;
  66         struct device *dev;
  67
  68         struct iio_trigger *trig;
  69         struct iio_cb_buffer *cb_buffer;
  70         struct iio_channel *adc_chan;
  71
  72         struct completion completion;
  73         u8 chan_select;
  74         /* 64-bit data + 64-bit naturally aligned timestamp */
  75         u32 buffer[4] __aligned(8);
  76 };
  77
  78 static const struct iio_chan_spec lmp91000_channels[] = {
  79         { /* chemical channel mV */
  80                 .type = IIO_VOLTAGE,
  81                 .channel = 0,
  82                 .address = LMP91000_REG_MODECN_3LEAD,
  83                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
  84                                       BIT(IIO_CHAN_INFO_OFFSET) |
  85                                       BIT(IIO_CHAN_INFO_SCALE),
  86                 .scan_index = 0,
  87                 .scan_type = {
  88                         .sign = 's',
  89                         .realbits = 32,
  90                         .storagebits = 32,
  91                 },
  92         },
  93         IIO_CHAN_SOFT_TIMESTAMP(1),
  94         { /* temperature channel mV */
  95                 .type = IIO_TEMP,
  96                 .channel = 1,
  97                 .address = LMP91000_REG_MODECN_TEMP,
  98                 .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
  99                 .scan_index = -1,
 100         },
 101 };
 102
 103 static int lmp91000_read(struct lmp91000_data *data, int channel, int *val)
 104 {
 105         int state, ret;
 106
 107         ret = regmap_read(data->regmap, LMP91000_REG_MODECN, &state);
 108         if (ret)
 109                 return -EINVAL;
 110
 111         ret = regmap_write(data->regmap, LMP91000_REG_MODECN, channel);
 112         if (ret)
 113                 return -EINVAL;
 114
 115         /* delay till first temperature reading is complete */
 116         if (state != channel && channel == LMP91000_REG_MODECN_TEMP)
 117                 usleep_range(3000, 4000);
 118
 119         data->chan_select = channel != LMP91000_REG_MODECN_3LEAD;
 120
 121         iio_trigger_poll_nested(data->trig);
 122
 123         ret = wait_for_completion_timeout(&data->completion, HZ);
 124         reinit_completion(&data->completion);
 125
 126         if (!ret)
 127                 return -ETIMEDOUT;
 128
 129         *val = data->buffer[data->chan_select];
 130
 131         return 0;
 132 }
 133
 134 static irqreturn_t lmp91000_buffer_handler(int irq, void *private)
 135 {
 136         struct iio_poll_func *pf = private;
 137         struct iio_dev *indio_dev = pf->indio_dev;
 138         struct lmp91000_data *data = iio_priv(indio_dev);
 139         int ret, val;
 140
 141         memset(data->buffer, 0, sizeof(data->buffer));
 142
 143         ret = lmp91000_read(data, LMP91000_REG_MODECN_3LEAD, &val);
 144         if (!ret) {
 145                 data->buffer[0] = val;
 146                 iio_push_to_buffers_with_timestamp(indio_dev, data->buffer,
 147                                                    iio_get_time_ns(indio_dev));
 148         }
 149
 150         iio_trigger_notify_done(indio_dev->trig);
 151
 152         return IRQ_HANDLED;
 153 }
 154
 155 static int lmp91000_read_raw(struct iio_dev *indio_dev,
 156                              struct iio_chan_spec const *chan,
 157                              int *val, int *val2, long mask)
 158 {
 159         struct lmp91000_data *data = iio_priv(indio_dev);
 160
 161         switch (mask) {
 162         case IIO_CHAN_INFO_RAW:
 163         case IIO_CHAN_INFO_PROCESSED: {
 164                 int ret = iio_channel_start_all_cb(data->cb_buffer);
 165
 166                 if (ret)
 167                         return ret;
 168
 169                 ret = lmp91000_read(data, chan->address, val);
 170
 171                 iio_channel_stop_all_cb(data->cb_buffer);
 172
 173                 if (ret)
 174                         return ret;
 175
 176                 if (mask == IIO_CHAN_INFO_PROCESSED) {
 177                         int tmp, i;
 178
 179                         ret = iio_convert_raw_to_processed(data->adc_chan,
 180                                                            *val, &tmp, 1);
 181                         if (ret)
 182                                 return ret;
 183
 184                         for (i = 0; i < ARRAY_SIZE(lmp91000_temp_lut); i++)
 185                                 if (lmp91000_temp_lut[i] < tmp)
 186                                         break;
 187
 188                         *val = (LMP91000_TEMP_BASE + i) * 1000;
 189                 }
 190                 return IIO_VAL_INT;
 191         }
 192         case IIO_CHAN_INFO_OFFSET:
 193                 return iio_read_channel_offset(data->adc_chan, val, val2);
 194         case IIO_CHAN_INFO_SCALE:
 195                 return iio_read_channel_scale(data->adc_chan, val, val2);
 196         }
 197
 198         return -EINVAL;
 199 }
 200
 201 static const struct iio_info lmp91000_info = {
 202         .read_raw = lmp91000_read_raw,
 203 };
 204
 205 static int lmp91000_read_config(struct lmp91000_data *data)
 206 {
 207         struct device *dev = data->dev;
 208         unsigned int reg, val;
 209         int i, ret;
 210
 211         ret = device_property_read_u32(dev, "ti,tia-gain-ohm", &val);
 212         if (ret) {
 213                 if (!device_property_read_bool(dev, "ti,external-tia-resistor")) {
 214                         dev_err(dev, "no ti,tia-gain-ohm defined and external resistor not specified\n");
 215                         return ret;
 216                 }
 217                 val = 0;
 218         }
 219
 220         ret = -EINVAL;
 221         for (i = 0; i < ARRAY_SIZE(lmp91000_tia_gain); i++) {
 222                 if (lmp91000_tia_gain[i] == val) {
 223                         reg = i << LMP91000_REG_TIACN_GAIN_SHIFT;
 224                         ret = 0;
 225                         break;
 226                 }
 227         }
 228
 229         if (ret) {
 230                 dev_err(dev, "invalid ti,tia-gain-ohm %d\n", val);
 231                 return ret;
 232         }
 233
 234         ret = device_property_read_u32(dev, "ti,rload-ohm", &val);
 235         if (ret) {
 236                 val = 100;
 237                 dev_info(dev, "no ti,rload-ohm defined, default to %d\n", val);
 238         }
 239
 240         ret = -EINVAL;
 241         for (i = 0; i < ARRAY_SIZE(lmp91000_rload); i++) {
 242                 if (lmp91000_rload[i] == val) {
 243                         reg |= i;
 244                         ret = 0;
 245                         break;
 246                 }
 247         }
 248
 249         if (ret) {
 250                 dev_err(dev, "invalid ti,rload-ohm %d\n", val);
 251                 return ret;
 252         }
 253
 254         regmap_write(data->regmap, LMP91000_REG_LOCK, 0);
 255         regmap_write(data->regmap, LMP91000_REG_TIACN, reg);
 256         regmap_write(data->regmap, LMP91000_REG_REFCN,
 257                      LMP91000_REG_REFCN_EXT_REF | LMP91000_REG_REFCN_50_ZERO);
 258         regmap_write(data->regmap, LMP91000_REG_LOCK, 1);
 259
 260         return 0;
 261 }
 262
 263 static int lmp91000_buffer_cb(const void *val, void *private)
 264 {
 265         struct iio_dev *indio_dev = private;
 266         struct lmp91000_data *data = iio_priv(indio_dev);
 267
 268         data->buffer[data->chan_select] = *((int *)val);
 269         complete_all(&data->completion);
 270
 271         return 0;
 272 }
 273
 274 static int lmp91000_buffer_postenable(struct iio_dev *indio_dev)
 275 {
 276         struct lmp91000_data *data = iio_priv(indio_dev);
 277
 278         return iio_channel_start_all_cb(data->cb_buffer);
 279 }
 280
 281 static int lmp91000_buffer_predisable(struct iio_dev *indio_dev)
 282 {
 283         struct lmp91000_data *data = iio_priv(indio_dev);
 284
 285         iio_channel_stop_all_cb(data->cb_buffer);
 286
 287         return 0;
 288 }
 289
 290 static const struct iio_buffer_setup_ops lmp91000_buffer_setup_ops = {
 291         .postenable = lmp91000_buffer_postenable,
 292         .predisable = lmp91000_buffer_predisable,
 293 };
 294
 295 static int lmp91000_probe(struct i2c_client *client)
 296 {
 297         struct device *dev = &client->dev;
 298         struct lmp91000_data *data;
 299         struct iio_dev *indio_dev;
 300         int ret;
 301
 302         indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
 303         if (!indio_dev)
 304                 return -ENOMEM;
 305
 306         indio_dev->info = &lmp91000_info;
 307         indio_dev->channels = lmp91000_channels;
 308         indio_dev->num_channels = ARRAY_SIZE(lmp91000_channels);
 309         indio_dev->name = LMP91000_DRV_NAME;
 310         indio_dev->modes = INDIO_DIRECT_MODE;
 311         i2c_set_clientdata(client, indio_dev);
 312
 313         data = iio_priv(indio_dev);
 314         data->dev = dev;
 315         data->regmap = devm_regmap_init_i2c(client, &lmp91000_regmap_config);
 316         if (IS_ERR(data->regmap)) {
 317                 dev_err(dev, "regmap initialization failed.\n");
 318                 return PTR_ERR(data->regmap);
 319         }
 320
 321         data->trig = devm_iio_trigger_alloc(dev, "%s-mux%d",
 322                                             indio_dev->name,
 323                                             iio_device_id(indio_dev));
 324         if (!data->trig) {
 325                 dev_err(dev, "cannot allocate iio trigger.\n");
 326                 return -ENOMEM;
 327         }
 328
 329         init_completion(&data->completion);
 330
 331         ret = lmp91000_read_config(data);
 332         if (ret)
 333                 return ret;
 334
 335         ret = iio_trigger_set_immutable(iio_channel_cb_get_iio_dev(data->cb_buffer),
 336                                         data->trig);
 337         if (ret) {
 338                 dev_err(dev, "cannot set immutable trigger.\n");
 339                 return ret;
 340         }
 341
 342         ret = iio_trigger_register(data->trig);
 343         if (ret) {
 344                 dev_err(dev, "cannot register iio trigger.\n");
 345                 return ret;
 346         }
 347
 348         ret = iio_triggered_buffer_setup(indio_dev, NULL,
 349                                          &lmp91000_buffer_handler,
 350                                          &lmp91000_buffer_setup_ops);
 351         if (ret)
 352                 goto error_unreg_trigger;
 353
 354         data->cb_buffer = iio_channel_get_all_cb(dev, &lmp91000_buffer_cb,
 355                                                  indio_dev);
 356
 357         if (IS_ERR(data->cb_buffer)) {
 358                 if (PTR_ERR(data->cb_buffer) == -ENODEV)
 359                         ret = -EPROBE_DEFER;
 360                 else
 361                         ret = PTR_ERR(data->cb_buffer);
 362
 363                 goto error_unreg_buffer;
 364         }
 365
 366         data->adc_chan = iio_channel_cb_get_channels(data->cb_buffer);
 367
 368         ret = iio_device_register(indio_dev);
 369         if (ret)
 370                 goto error_unreg_cb_buffer;
 371
 372         return 0;
 373
 374 error_unreg_cb_buffer:
 375         iio_channel_release_all_cb(data->cb_buffer);
 376
 377 error_unreg_buffer:
 378         iio_triggered_buffer_cleanup(indio_dev);
 379
 380 error_unreg_trigger:
 381         iio_trigger_unregister(data->trig);
 382
 383         return ret;
 384 }
 385
 386 static void lmp91000_remove(struct i2c_client *client)
 387 {
 388         struct iio_dev *indio_dev = i2c_get_clientdata(client);
 389         struct lmp91000_data *data = iio_priv(indio_dev);
 390
 391         iio_device_unregister(indio_dev);
 392
 393         iio_channel_stop_all_cb(data->cb_buffer);
 394         iio_channel_release_all_cb(data->cb_buffer);
 395
 396         iio_triggered_buffer_cleanup(indio_dev);
 397         iio_trigger_unregister(data->trig);
 398 }
 399
 400 static const struct of_device_id lmp91000_of_match[] = {
 401         { .compatible = "ti,lmp91000", },
 402         { .compatible = "ti,lmp91002", },
 403         { },
 404 };
 405 MODULE_DEVICE_TABLE(of, lmp91000_of_match);
 406
 407 static const struct i2c_device_id lmp91000_id[] = {
 408         { "lmp91000" },
 409         { "lmp91002" },
 410         {}
 411 };
 412 MODULE_DEVICE_TABLE(i2c, lmp91000_id);
 413
 414 static struct i2c_driver lmp91000_driver = {
 415         .driver = {
 416                 .name = LMP91000_DRV_NAME,
 417                 .of_match_table = lmp91000_of_match,
 418         },
 419         .probe = lmp91000_probe,
 420         .remove = lmp91000_remove,
 421         .id_table = lmp91000_id,
 422 };
 423 module_i2c_driver(lmp91000_driver);
 424
 425 MODULE_AUTHOR("Matt Ranostay <matt.ranostay@konsulko.com>");
 426 MODULE_DESCRIPTION("LMP91000 digital potentiostat");
 427 MODULE_LICENSE("GPL");