ad5110.c

  1// SPDX-License-Identifier: GPL-2.0+
  2/*
  3 * Analog Devices AD5110 digital potentiometer driver
  4 *
  5 * Copyright (C) 2021 Mugilraj Dhavachelvan <dmugil2000@gmail.com>
  6 *
  7 * Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/AD5110_5112_5114.pdf
  8 */
  9
 10#include <linux/bitfield.h>
 11#include <linux/delay.h>
 12#include <linux/device.h>
 13#include <linux/i2c.h>
 14#include <linux/module.h>
 15
 16#include <linux/iio/iio.h>
 17#include <linux/iio/sysfs.h>
 18
 19/* AD5110 commands */
 20#define AD5110_EEPROM_WR	1
 21#define AD5110_RDAC_WR		2
 22#define AD5110_SHUTDOWN	3
 23#define AD5110_RESET		4
 24#define AD5110_RDAC_RD		5
 25#define AD5110_EEPROM_RD	6
 26
 27/* AD5110_EEPROM_RD data */
 28#define AD5110_WIPER_POS	0
 29#define AD5110_RESISTOR_TOL	1
 30
 31#define AD5110_WIPER_RESISTANCE	70
 32
 33struct ad5110_cfg {
 34	int max_pos;
 35	int kohms;
 36	int shift;
 37};
 38
 39enum ad5110_type {
 40	AD5110_10,
 41	AD5110_80,
 42	AD5112_05,
 43	AD5112_10,
 44	AD5112_80,
 45	AD5114_10,
 46	AD5114_80,
 47};
 48
 49static const struct ad5110_cfg ad5110_cfg[] = {
 50	[AD5110_10] = { .max_pos = 128, .kohms = 10 },
 51	[AD5110_80] = { .max_pos = 128, .kohms = 80 },
 52	[AD5112_05] = { .max_pos = 64, .kohms = 5, .shift = 1 },
 53	[AD5112_10] = { .max_pos = 64, .kohms = 10, .shift = 1 },
 54	[AD5112_80] = { .max_pos = 64, .kohms = 80, .shift = 1 },
 55	[AD5114_10] = { .max_pos = 32, .kohms = 10, .shift = 2 },
 56	[AD5114_80] = { .max_pos = 32, .kohms = 80, .shift = 2 },
 57};
 58
 59struct ad5110_data {
 60	struct i2c_client       *client;
 61	s16			tol;		/* resistor tolerance */
 62	bool			enable;
 63	struct mutex            lock;
 64	const struct ad5110_cfg	*cfg;
 65	/*
 66	 * DMA (thus cache coherency maintenance) may require the
 67	 * transfer buffers to live in their own cache lines.
 68	 */
 69	u8			buf[2] __aligned(IIO_DMA_MINALIGN);
 70};
 71
 72static const struct iio_chan_spec ad5110_channels[] = {
 73	{
 74		.type = IIO_RESISTANCE,
 75		.output = 1,
 76		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_OFFSET) |
 77					BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_ENABLE),
 78	},
 79};
 80
 81static int ad5110_read(struct ad5110_data *data, u8 cmd, int *val)
 82{
 83	int ret;
 84
 85	mutex_lock(&data->lock);
 86	data->buf[0] = cmd;
 87	data->buf[1] = *val;
 88
 89	ret = i2c_master_send_dmasafe(data->client, data->buf, sizeof(data->buf));
 90	if (ret < 0) {
 91		goto error;
 92	} else if (ret != sizeof(data->buf)) {
 93		ret = -EIO;
 94		goto error;
 95	}
 96
 97	ret = i2c_master_recv_dmasafe(data->client, data->buf, 1);
 98	if (ret < 0) {
 99		goto error;
100	} else if (ret != 1) {
101		ret = -EIO;
102		goto error;
103	}
104
105	*val = data->buf[0];
106	ret = 0;
107
108error:
109	mutex_unlock(&data->lock);
110	return ret;
111}
112
113static int ad5110_write(struct ad5110_data *data, u8 cmd, u8 val)
114{
115	int ret;
116
117	mutex_lock(&data->lock);
118	data->buf[0] = cmd;
119	data->buf[1] = val;
120
121	ret = i2c_master_send_dmasafe(data->client, data->buf, sizeof(data->buf));
122	if (ret < 0) {
123		goto error;
124	} else if (ret != sizeof(data->buf)) {
125		ret = -EIO;
126		goto error;
127	}
128
129	ret = 0;
130
131error:
132	mutex_unlock(&data->lock);
133	return ret;
134}
135
136static int ad5110_resistor_tol(struct ad5110_data *data, u8 cmd, int val)
137{
138	int ret;
139
140	ret = ad5110_read(data, cmd, &val);
141	if (ret)
142		return ret;
143
144	data->tol = data->cfg->kohms * (val & GENMASK(6, 0)) * 10 / 8;
145	if (!(val & BIT(7)))
146		data->tol *= -1;
147
148	return 0;
149}
150
151static ssize_t store_eeprom_show(struct device *dev,
152				  struct device_attribute *attr,
153				  char *buf)
154{
155	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
156	struct ad5110_data *data = iio_priv(indio_dev);
157	int val = AD5110_WIPER_POS;
158	int ret;
159
160	ret = ad5110_read(data, AD5110_EEPROM_RD, &val);
161	if (ret)
162		return ret;
163
164	val = val >> data->cfg->shift;
165	return iio_format_value(buf, IIO_VAL_INT, 1, &val);
166}
167
168static ssize_t store_eeprom_store(struct device *dev,
169				   struct device_attribute *attr,
170				   const char *buf, size_t len)
171{
172	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
173	struct ad5110_data *data = iio_priv(indio_dev);
174	int ret;
175
176	ret = ad5110_write(data, AD5110_EEPROM_WR, 0);
177	if (ret) {
178		dev_err(&data->client->dev, "RDAC to EEPROM write failed\n");
179		return ret;
180	}
181
182	/* The storing of EEPROM data takes approximately 18 ms. */
183	msleep(20);
184
185	return len;
186}
187
188static IIO_DEVICE_ATTR_RW(store_eeprom, 0);
189
190static struct attribute *ad5110_attributes[] = {
191	&iio_dev_attr_store_eeprom.dev_attr.attr,
192	NULL
193};
194
195static const struct attribute_group ad5110_attribute_group = {
196	.attrs = ad5110_attributes,
197};
198
199static int ad5110_read_raw(struct iio_dev *indio_dev,
200			   struct iio_chan_spec const *chan,
201			   int *val, int *val2, long mask)
202{
203	struct ad5110_data *data = iio_priv(indio_dev);
204	int ret;
205
206	switch (mask) {
207	case IIO_CHAN_INFO_RAW:
208		ret = ad5110_read(data, AD5110_RDAC_RD, val);
209		if (ret)
210			return ret;
211
212		*val = *val >> data->cfg->shift;
213		return IIO_VAL_INT;
214	case IIO_CHAN_INFO_OFFSET:
215		*val = AD5110_WIPER_RESISTANCE * data->cfg->max_pos;
216		*val2 = 1000 * data->cfg->kohms + data->tol;
217		return IIO_VAL_FRACTIONAL;
218	case IIO_CHAN_INFO_SCALE:
219		*val = 1000 * data->cfg->kohms + data->tol;
220		*val2 = data->cfg->max_pos;
221		return IIO_VAL_FRACTIONAL;
222	case IIO_CHAN_INFO_ENABLE:
223		*val = data->enable;
224		return IIO_VAL_INT;
225	default:
226		return -EINVAL;
227	}
228}
229
230static int ad5110_write_raw(struct iio_dev *indio_dev,
231			    struct iio_chan_spec const *chan,
232			    int val, int val2, long mask)
233{
234	struct ad5110_data *data = iio_priv(indio_dev);
235	int ret;
236
237	switch (mask) {
238	case IIO_CHAN_INFO_RAW:
239		if (val > data->cfg->max_pos || val < 0)
240			return -EINVAL;
241
242		return ad5110_write(data, AD5110_RDAC_WR, val << data->cfg->shift);
243	case IIO_CHAN_INFO_ENABLE:
244		if (val < 0 || val > 1)
245			return -EINVAL;
246		if (data->enable == val)
247			return 0;
248		ret = ad5110_write(data, AD5110_SHUTDOWN, val ? 0 : 1);
249		if (ret)
250			return ret;
251		data->enable = val;
252		return 0;
253	default:
254		return -EINVAL;
255	}
256}
257
258static const struct iio_info ad5110_info = {
259	.read_raw = ad5110_read_raw,
260	.write_raw = ad5110_write_raw,
261	.attrs = &ad5110_attribute_group,
262};
263
264#define AD5110_COMPATIBLE(of_compatible, cfg) {	\
265			.compatible = of_compatible,	\
266			.data = &ad5110_cfg[cfg],	\
267}
268
269static const struct of_device_id ad5110_of_match[] = {
270	AD5110_COMPATIBLE("adi,ad5110-10", AD5110_10),
271	AD5110_COMPATIBLE("adi,ad5110-80", AD5110_80),
272	AD5110_COMPATIBLE("adi,ad5112-05", AD5112_05),
273	AD5110_COMPATIBLE("adi,ad5112-10", AD5112_10),
274	AD5110_COMPATIBLE("adi,ad5112-80", AD5112_80),
275	AD5110_COMPATIBLE("adi,ad5114-10", AD5114_10),
276	AD5110_COMPATIBLE("adi,ad5114-80", AD5114_80),
277	{ }
278};
279MODULE_DEVICE_TABLE(of, ad5110_of_match);
280
281#define AD5110_ID_TABLE(_name, cfg) {				\
282	.name = _name,						\
283	.driver_data = (kernel_ulong_t)&ad5110_cfg[cfg],	\
284}
285
286static const struct i2c_device_id ad5110_id[] = {
287	AD5110_ID_TABLE("ad5110-10", AD5110_10),
288	AD5110_ID_TABLE("ad5110-80", AD5110_80),
289	AD5110_ID_TABLE("ad5112-05", AD5112_05),
290	AD5110_ID_TABLE("ad5112-10", AD5112_10),
291	AD5110_ID_TABLE("ad5112-80", AD5112_80),
292	AD5110_ID_TABLE("ad5114-10", AD5114_10),
293	AD5110_ID_TABLE("ad5114-80", AD5114_80),
294	{ }
295};
296MODULE_DEVICE_TABLE(i2c, ad5110_id);
297
298static int ad5110_probe(struct i2c_client *client)
299{
300	struct device *dev = &client->dev;
301	struct iio_dev *indio_dev;
302	struct ad5110_data *data;
303	int ret;
304
305	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
306	if (!indio_dev)
307		return -ENOMEM;
308
309	data = iio_priv(indio_dev);
310	data->client = client;
311	mutex_init(&data->lock);
312	data->enable = 1;
313	data->cfg = i2c_get_match_data(client);
314
315	/* refresh RDAC register with EEPROM */
316	ret = ad5110_write(data, AD5110_RESET, 0);
317	if (ret) {
318		dev_err(dev, "Refresh RDAC with EEPROM failed\n");
319		return ret;
320	}
321
322	ret = ad5110_resistor_tol(data, AD5110_EEPROM_RD, AD5110_RESISTOR_TOL);
323	if (ret) {
324		dev_err(dev, "Read resistor tolerance failed\n");
325		return ret;
326	}
327
328	indio_dev->modes = INDIO_DIRECT_MODE;
329	indio_dev->info = &ad5110_info;
330	indio_dev->channels = ad5110_channels;
331	indio_dev->num_channels = ARRAY_SIZE(ad5110_channels);
332	indio_dev->name = client->name;
333
334	return devm_iio_device_register(dev, indio_dev);
335}
336
337static struct i2c_driver ad5110_driver = {
338	.driver = {
339		.name	= "ad5110",
340		.of_match_table = ad5110_of_match,
341	},
342	.probe		= ad5110_probe,
343	.id_table	= ad5110_id,
344};
345module_i2c_driver(ad5110_driver);
346
347MODULE_AUTHOR("Mugilraj Dhavachelvan <dmugil2000@gmail.com>");
348MODULE_DESCRIPTION("AD5110 digital potentiometer");
349MODULE_LICENSE("GPL v2");