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/delay.h>
14#include <linux/module.h>
15#include <linux/init.h>
16#include <linux/i2c.h>
17#include <linux/mutex.h>
18#include <linux/property.h>
19#include <linux/pm_runtime.h>
20#include <linux/regulator/consumer.h>
21#include <linux/units.h>
22
23#include <linux/iio/iio.h>
24#include <linux/iio/types.h>
25
26/* The ADS1100 has a single byte config register */
27
28/* Conversion in progress bit */
29#define ADS1100_CFG_ST_BSY	BIT(7)
30/* Single conversion bit */
31#define ADS1100_CFG_SC		BIT(4)
32/* Data rate */
33#define ADS1100_DR_MASK		GENMASK(3, 2)
34/* Gain */
35#define ADS1100_PGA_MASK	GENMASK(1, 0)
36
37#define ADS1100_CONTINUOUS	0
38#define	ADS1100_SINGLESHOT	ADS1100_CFG_SC
39
40#define ADS1100_SLEEP_DELAY_MS	2000
41
42static const int ads1100_data_rate[] = { 128, 32, 16, 8 };
43static const int ads1100_data_rate_bits[] = { 12, 14, 15, 16 };
44
45struct ads1100_data {
46	struct i2c_client *client;
47	struct regulator *reg_vdd;
48	struct mutex lock;
49	int scale_avail[2 * 4]; /* 4 gain settings */
50	u8 config;
51	bool supports_data_rate; /* Only the ADS1100 can select the rate */
52};
53
54static const struct iio_chan_spec ads1100_channel = {
55	.type = IIO_VOLTAGE,
56	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
57	.info_mask_shared_by_all =
58	    BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_SAMP_FREQ),
59	.info_mask_shared_by_all_available =
60	    BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_SAMP_FREQ),
61	.scan_type = {
62		      .sign = 's',
63		      .realbits = 16,
64		      .storagebits = 16,
65		      .endianness = IIO_CPU,
66		       },
67	.datasheet_name = "AIN",
68};
69
70static int ads1100_set_config_bits(struct ads1100_data *data, u8 mask, u8 value)
71{
72	int ret;
73	u8 config = (data->config & ~mask) | (value & mask);
74
75	if (data->config == config)
76		return 0;	/* Already done */
77
78	ret = i2c_master_send(data->client, &config, 1);
79	if (ret < 0)
80		return ret;
81
82	data->config = config;
83
84	return 0;
85};
86
87static int ads1100_data_bits(struct ads1100_data *data)
88{
89	return ads1100_data_rate_bits[FIELD_GET(ADS1100_DR_MASK, data->config)];
90}
91
92static int ads1100_get_adc_result(struct ads1100_data *data, int chan, int *val)
93{
94	int ret;
95	__be16 buffer;
96	s16 value;
97
98	if (chan != 0)
99		return -EINVAL;
100
101	ret = pm_runtime_resume_and_get(&data->client->dev);
102	if (ret < 0)
103		return ret;
104
105	ret = i2c_master_recv(data->client, (char *)&buffer, sizeof(buffer));
106
107	pm_runtime_mark_last_busy(&data->client->dev);
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	mutex_lock(&data->lock);
223	switch (mask) {
224	case IIO_CHAN_INFO_RAW:
225		ret = iio_device_claim_direct_mode(indio_dev);
226		if (ret)
227			break;
228
229		ret = ads1100_get_adc_result(data, chan->address, val);
230		if (ret >= 0)
231			ret = IIO_VAL_INT;
232		iio_device_release_direct_mode(indio_dev);
233		break;
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		ret = IIO_VAL_FRACTIONAL_LOG2;
239		break;
240	case IIO_CHAN_INFO_SAMP_FREQ:
241		*val = ads1100_data_rate[FIELD_GET(ADS1100_DR_MASK,
242						   data->config)];
243		ret = IIO_VAL_INT;
244		break;
245	default:
246		ret = -EINVAL;
247		break;
248	}
249	mutex_unlock(&data->lock);
250
251	return ret;
252}
253
254static int ads1100_write_raw(struct iio_dev *indio_dev,
255			     struct iio_chan_spec const *chan, int val,
256			     int val2, long mask)
257{
258	struct ads1100_data *data = iio_priv(indio_dev);
259	int ret;
260
261	mutex_lock(&data->lock);
262	switch (mask) {
263	case IIO_CHAN_INFO_SCALE:
264		ret = ads1100_set_scale(data, val, val2);
265		break;
266	case IIO_CHAN_INFO_SAMP_FREQ:
267		ret = ads1100_set_data_rate(data, chan->address, val);
268		break;
269	default:
270		ret = -EINVAL;
271		break;
272	}
273	mutex_unlock(&data->lock);
274
275	return ret;
276}
277
278static const struct iio_info ads1100_info = {
279	.read_avail = ads1100_read_avail,
280	.read_raw = ads1100_read_raw,
281	.write_raw = ads1100_write_raw,
282};
283
284static int ads1100_setup(struct ads1100_data *data)
285{
286	int ret;
287	u8 buffer[3];
288
289	/* Setup continuous sampling mode at 8sps */
290	buffer[0] = ADS1100_DR_MASK | ADS1100_CONTINUOUS;
291	ret = i2c_master_send(data->client, buffer, 1);
292	if (ret < 0)
293		return ret;
294
295	ret = i2c_master_recv(data->client, buffer, sizeof(buffer));
296	if (ret < 0)
297		return ret;
298
299	/* Config register returned in third byte, strip away the busy status */
300	data->config = buffer[2] & ~ADS1100_CFG_ST_BSY;
301
302	/* Detect the sample rate capability by checking the DR bits */
303	data->supports_data_rate = FIELD_GET(ADS1100_DR_MASK, buffer[2]) != 0;
304
305	return 0;
306}
307
308static void ads1100_reg_disable(void *reg)
309{
310	regulator_disable(reg);
311}
312
313static void ads1100_disable_continuous(void *data)
314{
315	ads1100_set_config_bits(data, ADS1100_CFG_SC, ADS1100_SINGLESHOT);
316}
317
318static int ads1100_probe(struct i2c_client *client)
319{
320	struct iio_dev *indio_dev;
321	struct ads1100_data *data;
322	struct device *dev = &client->dev;
323	int ret;
324
325	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
326	if (!indio_dev)
327		return -ENOMEM;
328
329	data = iio_priv(indio_dev);
330	dev_set_drvdata(dev, data);
331	data->client = client;
332	mutex_init(&data->lock);
333
334	indio_dev->name = "ads1100";
335	indio_dev->modes = INDIO_DIRECT_MODE;
336	indio_dev->channels = &ads1100_channel;
337	indio_dev->num_channels = 1;
338	indio_dev->info = &ads1100_info;
339
340	data->reg_vdd = devm_regulator_get(dev, "vdd");
341	if (IS_ERR(data->reg_vdd))
342		return dev_err_probe(dev, PTR_ERR(data->reg_vdd),
343				     "Failed to get vdd regulator\n");
344
345	ret = regulator_enable(data->reg_vdd);
346	if (ret < 0)
347		return dev_err_probe(dev, ret,
348				     "Failed to enable vdd regulator\n");
349
350	ret = devm_add_action_or_reset(dev, ads1100_reg_disable, data->reg_vdd);
351	if (ret)
352		return ret;
353
354	ret = ads1100_setup(data);
355	if (ret)
356		return dev_err_probe(dev, ret,
357				     "Failed to communicate with device\n");
358
359	ret = devm_add_action_or_reset(dev, ads1100_disable_continuous, data);
360	if (ret)
361		return ret;
362
363	ads1100_calc_scale_avail(data);
364
365	pm_runtime_set_autosuspend_delay(dev, ADS1100_SLEEP_DELAY_MS);
366	pm_runtime_use_autosuspend(dev);
367	pm_runtime_set_active(dev);
368	ret = devm_pm_runtime_enable(dev);
369	if (ret)
370		return dev_err_probe(dev, ret, "Failed to enable pm_runtime\n");
371
372	ret = devm_iio_device_register(dev, indio_dev);
373	if (ret)
374		return dev_err_probe(dev, ret,
375				     "Failed to register IIO device\n");
376
377	return 0;
378}
379
380static int ads1100_runtime_suspend(struct device *dev)
381{
382	struct ads1100_data *data = dev_get_drvdata(dev);
383
384	ads1100_set_config_bits(data, ADS1100_CFG_SC, ADS1100_SINGLESHOT);
385	regulator_disable(data->reg_vdd);
386
387	return 0;
388}
389
390static int ads1100_runtime_resume(struct device *dev)
391{
392	struct ads1100_data *data = dev_get_drvdata(dev);
393	int ret;
394
395	ret = regulator_enable(data->reg_vdd);
396	if (ret) {
397		dev_err(&data->client->dev, "Failed to enable Vdd\n");
398		return ret;
399	}
400
401	/*
402	 * We'll always change the mode bit in the config register, so there is
403	 * no need here to "force" a write to the config register. If the device
404	 * has been power-cycled, we'll re-write its config register now.
405	 */
406	return ads1100_set_config_bits(data, ADS1100_CFG_SC,
407				       ADS1100_CONTINUOUS);
408}
409
410static DEFINE_RUNTIME_DEV_PM_OPS(ads1100_pm_ops,
411				 ads1100_runtime_suspend,
412				 ads1100_runtime_resume,
413				 NULL);
414
415static const struct i2c_device_id ads1100_id[] = {
416	{ "ads1100" },
417	{ "ads1000" },
418	{ }
419};
420
421MODULE_DEVICE_TABLE(i2c, ads1100_id);
422
423static const struct of_device_id ads1100_of_match[] = {
424	{.compatible = "ti,ads1100" },
425	{.compatible = "ti,ads1000" },
426	{ }
427};
428
429MODULE_DEVICE_TABLE(of, ads1100_of_match);
430
431static struct i2c_driver ads1100_driver = {
432	.driver = {
433		   .name = "ads1100",
434		   .of_match_table = ads1100_of_match,
435		   .pm = pm_ptr(&ads1100_pm_ops),
436	},
437	.probe = ads1100_probe,
438	.id_table = ads1100_id,
439};
440
441module_i2c_driver(ads1100_driver);
442
443MODULE_AUTHOR("Mike Looijmans <mike.looijmans@topic.nl>");
444MODULE_DESCRIPTION("Texas Instruments ADS1100 ADC driver");
445MODULE_LICENSE("GPL");
446