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
281static const struct i2c_device_id ad5110_id[] = {
282	{ "ad5110-10", AD5110_10 },
283	{ "ad5110-80", AD5110_80 },
284	{ "ad5112-05", AD5112_05 },
285	{ "ad5112-10", AD5112_10 },
286	{ "ad5112-80", AD5112_80 },
287	{ "ad5114-10", AD5114_10 },
288	{ "ad5114-80", AD5114_80 },
289	{ }
290};
291MODULE_DEVICE_TABLE(i2c, ad5110_id);
292
293static int ad5110_probe(struct i2c_client *client)
294{
295	struct device *dev = &client->dev;
296	struct iio_dev *indio_dev;
297	struct ad5110_data *data;
298	int ret;
299
300	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
301	if (!indio_dev)
302		return -ENOMEM;
303
304	data = iio_priv(indio_dev);
305	data->client = client;
306	mutex_init(&data->lock);
307	data->enable = 1;
308	data->cfg = device_get_match_data(dev);
309
310	/* refresh RDAC register with EEPROM */
311	ret = ad5110_write(data, AD5110_RESET, 0);
312	if (ret) {
313		dev_err(dev, "Refresh RDAC with EEPROM failed\n");
314		return ret;
315	}
316
317	ret = ad5110_resistor_tol(data, AD5110_EEPROM_RD, AD5110_RESISTOR_TOL);
318	if (ret) {
319		dev_err(dev, "Read resistor tolerance failed\n");
320		return ret;
321	}
322
323	indio_dev->modes = INDIO_DIRECT_MODE;
324	indio_dev->info = &ad5110_info;
325	indio_dev->channels = ad5110_channels;
326	indio_dev->num_channels = ARRAY_SIZE(ad5110_channels);
327	indio_dev->name = client->name;
328
329	return devm_iio_device_register(dev, indio_dev);
330}
331
332static struct i2c_driver ad5110_driver = {
333	.driver = {
334		.name	= "ad5110",
335		.of_match_table = ad5110_of_match,
336	},
337	.probe		= ad5110_probe,
338	.id_table	= ad5110_id,
339};
340module_i2c_driver(ad5110_driver);
341
342MODULE_AUTHOR("Mugilraj Dhavachelvan <dmugil2000@gmail.com>");
343MODULE_DESCRIPTION("AD5110 digital potentiometer");
344MODULE_LICENSE("GPL v2");
345