ti-ads1100.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * ADS1100 - Texas Instruments Analog-to-Digital Converter
  4 *
  5 * Copyright (c) 2023, Topic Embedded Products
  6 *
  7 * Datasheet: https://www.ti.com/lit/gpn/ads1100
  8 * IIO driver for ADS1100 and ADS1000 ADC 16-bit I2C
  9 */
 10
 11#include <linux/bitfield.h>
 12#include <linux/bits.h>
 13#include <linux/cleanup.h>
 14#include <linux/delay.h>
 15#include <linux/module.h>
 16#include <linux/init.h>
 17#include <linux/i2c.h>
 18#include <linux/mutex.h>
 19#include <linux/property.h>
 20#include <linux/pm_runtime.h>
 21#include <linux/regulator/consumer.h>
 22#include <linux/units.h>
 23
 24#include <linux/iio/iio.h>
 25#include <linux/iio/types.h>
 26
 27/* The ADS1100 has a single byte config register */
 28
 29/* Conversion in progress bit */
 30#define ADS1100_CFG_ST_BSY	BIT(7)
 31/* Single conversion bit */
 32#define ADS1100_CFG_SC		BIT(4)
 33/* Data rate */
 34#define ADS1100_DR_MASK		GENMASK(3, 2)
 35/* Gain */
 36#define ADS1100_PGA_MASK	GENMASK(1, 0)
 37
 38#define ADS1100_CONTINUOUS	0
 39#define	ADS1100_SINGLESHOT	ADS1100_CFG_SC
 40
 41#define ADS1100_SLEEP_DELAY_MS	2000
 42
 43static const int ads1100_data_rate[] = { 128, 32, 16, 8 };
 44static const int ads1100_data_rate_bits[] = { 12, 14, 15, 16 };
 45
 46struct ads1100_data {
 47	struct i2c_client *client;
 48	struct regulator *reg_vdd;
 49	struct mutex lock;
 50	int scale_avail[2 * 4]; /* 4 gain settings */
 51	u8 config;
 52	bool supports_data_rate; /* Only the ADS1100 can select the rate */
 53};
 54
 55static const struct iio_chan_spec ads1100_channel = {
 56	.type = IIO_VOLTAGE,
 57	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
 58	.info_mask_shared_by_all =
 59	    BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_SAMP_FREQ),
 60	.info_mask_shared_by_all_available =
 61	    BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_SAMP_FREQ),
 62	.scan_type = {
 63		      .sign = 's',
 64		      .realbits = 16,
 65		      .storagebits = 16,
 66		      .endianness = IIO_CPU,
 67		       },
 68	.datasheet_name = "AIN",
 69};
 70
 71static int ads1100_set_config_bits(struct ads1100_data *data, u8 mask, u8 value)
 72{
 73	int ret;
 74	u8 config = (data->config & ~mask) | (value & mask);
 75
 76	if (data->config == config)
 77		return 0;	/* Already done */
 78
 79	ret = i2c_master_send(data->client, &config, 1);
 80	if (ret < 0)
 81		return ret;
 82
 83	data->config = config;
 84
 85	return 0;
 86};
 87
 88static int ads1100_data_bits(struct ads1100_data *data)
 89{
 90	return ads1100_data_rate_bits[FIELD_GET(ADS1100_DR_MASK, data->config)];
 91}
 92
 93static int ads1100_get_adc_result(struct ads1100_data *data, int chan, int *val)
 94{
 95	int ret;
 96	__be16 buffer;
 97	s16 value;
 98
 99	if (chan != 0)
100		return -EINVAL;
101
102	ret = pm_runtime_resume_and_get(&data->client->dev);
103	if (ret < 0)
104		return ret;
105
106	ret = i2c_master_recv(data->client, (char *)&buffer, sizeof(buffer));
107
108	pm_runtime_put_autosuspend(&data->client->dev);
109
110	if (ret < 0) {
111		dev_err(&data->client->dev, "I2C read fail: %d\n", ret);
112		return ret;
113	}
114
115	/* Value is always 16-bit 2's complement */
116	value = be16_to_cpu(buffer);
117
118	/* Shift result to compensate for bit resolution vs. sample rate */
119	value <<= 16 - ads1100_data_bits(data);
120
121	*val = sign_extend32(value, 15);
122
123	return 0;
124}
125
126static int ads1100_set_scale(struct ads1100_data *data, int val, int val2)
127{
128	int microvolts;
129	int gain;
130
131	/* With Vdd between 2.7 and 5V, the scale is always below 1 */
132	if (val)
133		return -EINVAL;
134
135	if (!val2)
136		return -EINVAL;
137
138	microvolts = regulator_get_voltage(data->reg_vdd);
139	/*
140	 * val2 is in 'micro' units, n = val2 / 1000000
141	 * result must be millivolts, d = microvolts / 1000
142	 * the full-scale value is d/n, corresponds to 2^15,
143	 * hence the gain = (d / n) >> 15, factoring out the 1000 and moving the
144	 * bitshift so everything fits in 32-bits yields this formula.
145	 */
146	gain = DIV_ROUND_CLOSEST(microvolts, BIT(15)) * MILLI / val2;
147	if (gain < BIT(0) || gain > BIT(3))
148		return -EINVAL;
149
150	ads1100_set_config_bits(data, ADS1100_PGA_MASK, ffs(gain) - 1);
151
152	return 0;
153}
154
155static int ads1100_set_data_rate(struct ads1100_data *data, int chan, int rate)
156{
157	unsigned int i;
158	unsigned int size;
159
160	size = data->supports_data_rate ? ARRAY_SIZE(ads1100_data_rate) : 1;
161	for (i = 0; i < size; i++) {
162		if (ads1100_data_rate[i] == rate)
163			return ads1100_set_config_bits(data, ADS1100_DR_MASK,
164						       FIELD_PREP(ADS1100_DR_MASK, i));
165	}
166
167	return -EINVAL;
168}
169
170static int ads1100_get_vdd_millivolts(struct ads1100_data *data)
171{
172	return regulator_get_voltage(data->reg_vdd) / (MICRO / MILLI);
173}
174
175static void ads1100_calc_scale_avail(struct ads1100_data *data)
176{
177	int millivolts = ads1100_get_vdd_millivolts(data);
178	unsigned int i;
179
180	for (i = 0; i < ARRAY_SIZE(data->scale_avail) / 2; i++) {
181		data->scale_avail[i * 2 + 0] = millivolts;
182		data->scale_avail[i * 2 + 1] = 15 + i;
183	}
184}
185
186static int ads1100_read_avail(struct iio_dev *indio_dev,
187			      struct iio_chan_spec const *chan,
188			      const int **vals, int *type, int *length,
189			      long mask)
190{
191	struct ads1100_data *data = iio_priv(indio_dev);
192
193	if (chan->type != IIO_VOLTAGE)
194		return -EINVAL;
195
196	switch (mask) {
197	case IIO_CHAN_INFO_SAMP_FREQ:
198		*type = IIO_VAL_INT;
199		*vals = ads1100_data_rate;
200		if (data->supports_data_rate)
201			*length = ARRAY_SIZE(ads1100_data_rate);
202		else
203			*length = 1;
204		return IIO_AVAIL_LIST;
205	case IIO_CHAN_INFO_SCALE:
206		*type = IIO_VAL_FRACTIONAL_LOG2;
207		*vals = data->scale_avail;
208		*length = ARRAY_SIZE(data->scale_avail);
209		return IIO_AVAIL_LIST;
210	default:
211		return -EINVAL;
212	}
213}
214
215static int ads1100_read_raw(struct iio_dev *indio_dev,
216			    struct iio_chan_spec const *chan, int *val,
217			    int *val2, long mask)
218{
219	int ret;
220	struct ads1100_data *data = iio_priv(indio_dev);
221
222	guard(mutex)(&data->lock);
223	switch (mask) {
224	case IIO_CHAN_INFO_RAW:
225		if (!iio_device_claim_direct(indio_dev))
226			return -EBUSY;
227
228		ret = ads1100_get_adc_result(data, chan->address, val);
229		iio_device_release_direct(indio_dev);
230		if (ret < 0)
231			return ret;
232
233		return IIO_VAL_INT;
234	case IIO_CHAN_INFO_SCALE:
235		/* full-scale is the supply voltage in millivolts */
236		*val = ads1100_get_vdd_millivolts(data);
237		*val2 = 15 + FIELD_GET(ADS1100_PGA_MASK, data->config);
238		return IIO_VAL_FRACTIONAL_LOG2;
239	case IIO_CHAN_INFO_SAMP_FREQ:
240		*val = ads1100_data_rate[FIELD_GET(ADS1100_DR_MASK,
241						   data->config)];
242		return IIO_VAL_INT;
243	default:
244		return -EINVAL;
245	}
246}
247
248static int ads1100_write_raw(struct iio_dev *indio_dev,
249			     struct iio_chan_spec const *chan, int val,
250			     int val2, long mask)
251{
252	struct ads1100_data *data = iio_priv(indio_dev);
253
254	guard(mutex)(&data->lock);
255	switch (mask) {
256	case IIO_CHAN_INFO_SCALE:
257		return ads1100_set_scale(data, val, val2);
258	case IIO_CHAN_INFO_SAMP_FREQ:
259		return ads1100_set_data_rate(data, chan->address, val);
260	default:
261		return -EINVAL;
262	}
263}
264
265static const struct iio_info ads1100_info = {
266	.read_avail = ads1100_read_avail,
267	.read_raw = ads1100_read_raw,
268	.write_raw = ads1100_write_raw,
269};
270
271static int ads1100_setup(struct ads1100_data *data)
272{
273	int ret;
274	u8 buffer[3];
275
276	/* Setup continuous sampling mode at 8sps */
277	buffer[0] = ADS1100_DR_MASK | ADS1100_CONTINUOUS;
278	ret = i2c_master_send(data->client, buffer, 1);
279	if (ret < 0)
280		return ret;
281
282	ret = i2c_master_recv(data->client, buffer, sizeof(buffer));
283	if (ret < 0)
284		return ret;
285
286	/* Config register returned in third byte, strip away the busy status */
287	data->config = buffer[2] & ~ADS1100_CFG_ST_BSY;
288
289	/* Detect the sample rate capability by checking the DR bits */
290	data->supports_data_rate = FIELD_GET(ADS1100_DR_MASK, buffer[2]) != 0;
291
292	return 0;
293}
294
295static void ads1100_reg_disable(void *reg)
296{
297	regulator_disable(reg);
298}
299
300static void ads1100_disable_continuous(void *data)
301{
302	ads1100_set_config_bits(data, ADS1100_CFG_SC, ADS1100_SINGLESHOT);
303}
304
305static int ads1100_probe(struct i2c_client *client)
306{
307	struct iio_dev *indio_dev;
308	struct ads1100_data *data;
309	struct device *dev = &client->dev;
310	int ret;
311
312	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
313	if (!indio_dev)
314		return -ENOMEM;
315
316	data = iio_priv(indio_dev);
317	dev_set_drvdata(dev, data);
318	data->client = client;
319	mutex_init(&data->lock);
320
321	indio_dev->name = "ads1100";
322	indio_dev->modes = INDIO_DIRECT_MODE;
323	indio_dev->channels = &ads1100_channel;
324	indio_dev->num_channels = 1;
325	indio_dev->info = &ads1100_info;
326
327	data->reg_vdd = devm_regulator_get(dev, "vdd");
328	if (IS_ERR(data->reg_vdd))
329		return dev_err_probe(dev, PTR_ERR(data->reg_vdd),
330				     "Failed to get vdd regulator\n");
331
332	ret = regulator_enable(data->reg_vdd);
333	if (ret < 0)
334		return dev_err_probe(dev, ret,
335				     "Failed to enable vdd regulator\n");
336
337	ret = devm_add_action_or_reset(dev, ads1100_reg_disable, data->reg_vdd);
338	if (ret)
339		return ret;
340
341	ret = ads1100_setup(data);
342	if (ret)
343		return dev_err_probe(dev, ret,
344				     "Failed to communicate with device\n");
345
346	ret = devm_add_action_or_reset(dev, ads1100_disable_continuous, data);
347	if (ret)
348		return ret;
349
350	ads1100_calc_scale_avail(data);
351
352	pm_runtime_set_autosuspend_delay(dev, ADS1100_SLEEP_DELAY_MS);
353	pm_runtime_use_autosuspend(dev);
354	pm_runtime_set_active(dev);
355	ret = devm_pm_runtime_enable(dev);
356	if (ret)
357		return dev_err_probe(dev, ret, "Failed to enable pm_runtime\n");
358
359	ret = devm_iio_device_register(dev, indio_dev);
360	if (ret)
361		return dev_err_probe(dev, ret,
362				     "Failed to register IIO device\n");
363
364	return 0;
365}
366
367static int ads1100_runtime_suspend(struct device *dev)
368{
369	struct ads1100_data *data = dev_get_drvdata(dev);
370
371	ads1100_set_config_bits(data, ADS1100_CFG_SC, ADS1100_SINGLESHOT);
372	regulator_disable(data->reg_vdd);
373
374	return 0;
375}
376
377static int ads1100_runtime_resume(struct device *dev)
378{
379	struct ads1100_data *data = dev_get_drvdata(dev);
380	int ret;
381
382	ret = regulator_enable(data->reg_vdd);
383	if (ret) {
384		dev_err(&data->client->dev, "Failed to enable Vdd\n");
385		return ret;
386	}
387
388	/*
389	 * We'll always change the mode bit in the config register, so there is
390	 * no need here to "force" a write to the config register. If the device
391	 * has been power-cycled, we'll re-write its config register now.
392	 */
393	return ads1100_set_config_bits(data, ADS1100_CFG_SC,
394				       ADS1100_CONTINUOUS);
395}
396
397static DEFINE_RUNTIME_DEV_PM_OPS(ads1100_pm_ops,
398				 ads1100_runtime_suspend,
399				 ads1100_runtime_resume,
400				 NULL);
401
402static const struct i2c_device_id ads1100_id[] = {
403	{ "ads1100" },
404	{ "ads1000" },
405	{ }
406};
407
408MODULE_DEVICE_TABLE(i2c, ads1100_id);
409
410static const struct of_device_id ads1100_of_match[] = {
411	{.compatible = "ti,ads1100" },
412	{.compatible = "ti,ads1000" },
413	{ }
414};
415
416MODULE_DEVICE_TABLE(of, ads1100_of_match);
417
418static struct i2c_driver ads1100_driver = {
419	.driver = {
420		   .name = "ads1100",
421		   .of_match_table = ads1100_of_match,
422		   .pm = pm_ptr(&ads1100_pm_ops),
423	},
424	.probe = ads1100_probe,
425	.id_table = ads1100_id,
426};
427
428module_i2c_driver(ads1100_driver);
429
430MODULE_AUTHOR("Mike Looijmans <mike.looijmans@topic.nl>");
431MODULE_DESCRIPTION("Texas Instruments ADS1100 ADC driver");
432MODULE_LICENSE("GPL");