1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Maxim Integrated DS1803 and similar digital potentiometer driver
4 * Copyright (c) 2016 Slawomir Stepien
5 * Copyright (c) 2022 Jagath Jog J
6 *
7 * Datasheet: https://datasheets.maximintegrated.com/en/ds/DS1803.pdf
8 * Datasheet: https://datasheets.maximintegrated.com/en/ds/DS3502.pdf
9 *
10 * DEVID	#Wipers	#Positions	Resistor Opts (kOhm)	i2c address
11 * ds1803	2	256		10, 50, 100		0101xxx
12 * ds3502	1	128		10			01010xx
13 */
14
15#include <linux/err.h>
16#include <linux/export.h>
17#include <linux/i2c.h>
18#include <linux/iio/iio.h>
19#include <linux/module.h>
20#include <linux/mod_devicetable.h>
21#include <linux/property.h>
22
23#define DS1803_WIPER_0         0xA9
24#define DS1803_WIPER_1         0xAA
25#define DS3502_WR_IVR          0x00
26
27enum ds1803_type {
28	DS1803_010,
29	DS1803_050,
30	DS1803_100,
31	DS3502,
32};
33
34struct ds1803_cfg {
35	int wipers;
36	int avail[3];
37	int kohms;
38	const struct iio_chan_spec *channels;
39	u8 num_channels;
40	int (*read)(struct iio_dev *indio_dev,
41		    struct iio_chan_spec const *chan, int *val);
42};
43
44struct ds1803_data {
45	struct i2c_client *client;
46	const struct ds1803_cfg *cfg;
47};
48
49#define DS1803_CHANNEL(ch, addr) {					\
50	.type = IIO_RESISTANCE,						\
51	.indexed = 1,							\
52	.output = 1,							\
53	.channel = (ch),						\
54	.address = (addr),						\
55	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),			\
56	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),		\
57	.info_mask_shared_by_type_available = BIT(IIO_CHAN_INFO_RAW),   \
58}
59
60static const struct iio_chan_spec ds1803_channels[] = {
61	DS1803_CHANNEL(0, DS1803_WIPER_0),
62	DS1803_CHANNEL(1, DS1803_WIPER_1),
63};
64
65static const struct iio_chan_spec ds3502_channels[] = {
66	DS1803_CHANNEL(0, DS3502_WR_IVR),
67};
68
69static int ds1803_read(struct iio_dev *indio_dev,
70		       struct iio_chan_spec const *chan,
71		       int *val)
72{
73	struct ds1803_data *data = iio_priv(indio_dev);
74	int ret;
75	u8 result[ARRAY_SIZE(ds1803_channels)];
76
77	ret = i2c_master_recv(data->client, result, indio_dev->num_channels);
78	if (ret < 0)
79		return ret;
80
81	*val = result[chan->channel];
82	return ret;
83}
84
85static int ds3502_read(struct iio_dev *indio_dev,
86		       struct iio_chan_spec const *chan,
87		       int *val)
88{
89	struct ds1803_data *data = iio_priv(indio_dev);
90	int ret;
91
92	ret = i2c_smbus_read_byte_data(data->client, chan->address);
93	if (ret < 0)
94		return ret;
95
96	*val = ret;
97	return ret;
98}
99
100static const struct ds1803_cfg ds1803_cfg[] = {
101	[DS1803_010] = {
102		.wipers = 2,
103		.avail = { 0, 1, 255 },
104		.kohms =  10,
105		.channels = ds1803_channels,
106		.num_channels = ARRAY_SIZE(ds1803_channels),
107		.read = ds1803_read,
108	},
109	[DS1803_050] = {
110		.wipers = 2,
111		.avail = { 0, 1, 255 },
112		.kohms =  50,
113		.channels = ds1803_channels,
114		.num_channels = ARRAY_SIZE(ds1803_channels),
115		.read = ds1803_read,
116	},
117	[DS1803_100] = {
118		.wipers = 2,
119		.avail = { 0, 1, 255 },
120		.kohms = 100,
121		.channels = ds1803_channels,
122		.num_channels = ARRAY_SIZE(ds1803_channels),
123		.read = ds1803_read,
124	},
125	[DS3502] = {
126	  .wipers = 1,
127	  .avail = { 0, 1, 127 },
128	  .kohms =  10,
129	  .channels = ds3502_channels,
130	  .num_channels = ARRAY_SIZE(ds3502_channels),
131	  .read = ds3502_read,
132	},
133};
134
135static int ds1803_read_raw(struct iio_dev *indio_dev,
136			   struct iio_chan_spec const *chan,
137			   int *val, int *val2, long mask)
138{
139	struct ds1803_data *data = iio_priv(indio_dev);
140	int ret;
141
142	switch (mask) {
143	case IIO_CHAN_INFO_RAW:
144		ret = data->cfg->read(indio_dev, chan, val);
145		if (ret < 0)
146			return ret;
147
148		return IIO_VAL_INT;
149
150	case IIO_CHAN_INFO_SCALE:
151		*val = 1000 * data->cfg->kohms;
152		*val2 = data->cfg->avail[2]; /* Max wiper position */
153		return IIO_VAL_FRACTIONAL;
154	}
155
156	return -EINVAL;
157}
158
159static int ds1803_write_raw(struct iio_dev *indio_dev,
160			    struct iio_chan_spec const *chan,
161			    int val, int val2, long mask)
162{
163	struct ds1803_data *data = iio_priv(indio_dev);
164	u8 addr = chan->address;
165	int max_pos = data->cfg->avail[2];
166
167	if (val2 != 0)
168		return -EINVAL;
169
170	switch (mask) {
171	case IIO_CHAN_INFO_RAW:
172		if (val > max_pos || val < 0)
173			return -EINVAL;
174		break;
175	default:
176		return -EINVAL;
177	}
178
179	return i2c_smbus_write_byte_data(data->client, addr, val);
180}
181
182static int ds1803_read_avail(struct iio_dev *indio_dev,
183			     struct iio_chan_spec const *chan,
184			     const int **vals, int *type,
185			     int *length, long mask)
186{
187	struct ds1803_data *data = iio_priv(indio_dev);
188
189	switch (mask) {
190	case IIO_CHAN_INFO_RAW:
191		*vals = data->cfg->avail;
192		*length = ARRAY_SIZE(data->cfg->avail);
193		*type = IIO_VAL_INT;
194		return IIO_AVAIL_RANGE;
195	}
196	return -EINVAL;
197}
198
199static const struct iio_info ds1803_info = {
200	.read_raw = ds1803_read_raw,
201	.write_raw = ds1803_write_raw,
202	.read_avail = ds1803_read_avail,
203};
204
205static int ds1803_probe(struct i2c_client *client)
206{
207	const struct i2c_device_id *id = i2c_client_get_device_id(client);
208	struct device *dev = &client->dev;
209	struct ds1803_data *data;
210	struct iio_dev *indio_dev;
211
212	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
213	if (!indio_dev)
214		return -ENOMEM;
215
216	i2c_set_clientdata(client, indio_dev);
217
218	data = iio_priv(indio_dev);
219	data->client = client;
220	data->cfg = device_get_match_data(dev);
221	if (!data->cfg)
222		data->cfg = &ds1803_cfg[id->driver_data];
223
224	indio_dev->info = &ds1803_info;
225	indio_dev->channels = data->cfg->channels;
226	indio_dev->num_channels = data->cfg->num_channels;
227	indio_dev->name = client->name;
228
229	return devm_iio_device_register(dev, indio_dev);
230}
231
232static const struct of_device_id ds1803_dt_ids[] = {
233	{ .compatible = "maxim,ds1803-010", .data = &ds1803_cfg[DS1803_010] },
234	{ .compatible = "maxim,ds1803-050", .data = &ds1803_cfg[DS1803_050] },
235	{ .compatible = "maxim,ds1803-100", .data = &ds1803_cfg[DS1803_100] },
236	{ .compatible = "maxim,ds3502", .data = &ds1803_cfg[DS3502] },
237	{}
238};
239MODULE_DEVICE_TABLE(of, ds1803_dt_ids);
240
241static const struct i2c_device_id ds1803_id[] = {
242	{ "ds1803-010", DS1803_010 },
243	{ "ds1803-050", DS1803_050 },
244	{ "ds1803-100", DS1803_100 },
245	{ "ds3502", DS3502 },
246	{}
247};
248MODULE_DEVICE_TABLE(i2c, ds1803_id);
249
250static struct i2c_driver ds1803_driver = {
251	.driver = {
252		.name	= "ds1803",
253		.of_match_table = ds1803_dt_ids,
254	},
255	.probe		= ds1803_probe,
256	.id_table	= ds1803_id,
257};
258
259module_i2c_driver(ds1803_driver);
260
261MODULE_AUTHOR("Slawomir Stepien <sst@poczta.fm>");
262MODULE_AUTHOR("Jagath Jog J <jagathjog1996@gmail.com>");
263MODULE_DESCRIPTION("DS1803 digital potentiometer");
264MODULE_LICENSE("GPL v2");
265