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
 37static const int lmp91000_tia_gain[] = { 0, 2750, 3500, 7000, 14000, 35000,
 38					 120000, 350000 };
 39
 40static const int lmp91000_rload[] = { 10, 33, 50, 100 };
 41
 42#define LMP91000_TEMP_BASE	-40
 43
 44static 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
 59static const struct regmap_config lmp91000_regmap_config = {
 60	.reg_bits = 8,
 61	.val_bits = 8,
 62};
 63
 64struct 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
 78static 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
103static 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
134static 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
155static 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
201static const struct iio_info lmp91000_info = {
202	.read_raw = lmp91000_read_raw,
203};
204
205static 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
263static 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
274static 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
281static 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
290static const struct iio_buffer_setup_ops lmp91000_buffer_setup_ops = {
291	.postenable = lmp91000_buffer_postenable,
292	.predisable = lmp91000_buffer_predisable,
293};
294
295static 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		return -ENOMEM;
326
327	init_completion(&data->completion);
328
329	ret = lmp91000_read_config(data);
330	if (ret)
331		return ret;
332
333	ret = iio_trigger_set_immutable(iio_channel_cb_get_iio_dev(data->cb_buffer),
334					data->trig);
335	if (ret) {
336		dev_err(dev, "cannot set immutable trigger.\n");
337		return ret;
338	}
339
340	ret = iio_trigger_register(data->trig);
341	if (ret) {
342		dev_err(dev, "cannot register iio trigger.\n");
343		return ret;
344	}
345
346	ret = iio_triggered_buffer_setup(indio_dev, NULL,
347					 &lmp91000_buffer_handler,
348					 &lmp91000_buffer_setup_ops);
349	if (ret)
350		goto error_unreg_trigger;
351
352	data->cb_buffer = iio_channel_get_all_cb(dev, &lmp91000_buffer_cb,
353						 indio_dev);
354
355	if (IS_ERR(data->cb_buffer)) {
356		if (PTR_ERR(data->cb_buffer) == -ENODEV)
357			ret = -EPROBE_DEFER;
358		else
359			ret = PTR_ERR(data->cb_buffer);
360
361		goto error_unreg_buffer;
362	}
363
364	data->adc_chan = iio_channel_cb_get_channels(data->cb_buffer);
365
366	ret = iio_device_register(indio_dev);
367	if (ret)
368		goto error_unreg_cb_buffer;
369
370	return 0;
371
372error_unreg_cb_buffer:
373	iio_channel_release_all_cb(data->cb_buffer);
374
375error_unreg_buffer:
376	iio_triggered_buffer_cleanup(indio_dev);
377
378error_unreg_trigger:
379	iio_trigger_unregister(data->trig);
380
381	return ret;
382}
383
384static void lmp91000_remove(struct i2c_client *client)
385{
386	struct iio_dev *indio_dev = i2c_get_clientdata(client);
387	struct lmp91000_data *data = iio_priv(indio_dev);
388
389	iio_device_unregister(indio_dev);
390
391	iio_channel_stop_all_cb(data->cb_buffer);
392	iio_channel_release_all_cb(data->cb_buffer);
393
394	iio_triggered_buffer_cleanup(indio_dev);
395	iio_trigger_unregister(data->trig);
396}
397
398static const struct of_device_id lmp91000_of_match[] = {
399	{ .compatible = "ti,lmp91000", },
400	{ .compatible = "ti,lmp91002", },
401	{ }
402};
403MODULE_DEVICE_TABLE(of, lmp91000_of_match);
404
405static const struct i2c_device_id lmp91000_id[] = {
406	{ "lmp91000" },
407	{ "lmp91002" },
408	{ }
409};
410MODULE_DEVICE_TABLE(i2c, lmp91000_id);
411
412static struct i2c_driver lmp91000_driver = {
413	.driver = {
414		.name = LMP91000_DRV_NAME,
415		.of_match_table = lmp91000_of_match,
416	},
417	.probe = lmp91000_probe,
418	.remove = lmp91000_remove,
419	.id_table = lmp91000_id,
420};
421module_i2c_driver(lmp91000_driver);
422
423MODULE_AUTHOR("Matt Ranostay <matt.ranostay@konsulko.com>");
424MODULE_DESCRIPTION("LMP91000 digital potentiostat");
425MODULE_LICENSE("GPL");