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 
27 enum ds1803_type {
28 	DS1803_010,
29 	DS1803_050,
30 	DS1803_100,
31 	DS3502,
32 };
33 
34 struct 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 
44 struct 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 
60 static const struct iio_chan_spec ds1803_channels[] = {
61 	DS1803_CHANNEL(0, DS1803_WIPER_0),
62 	DS1803_CHANNEL(1, DS1803_WIPER_1),
63 };
64 
65 static const struct iio_chan_spec ds3502_channels[] = {
66 	DS1803_CHANNEL(0, DS3502_WR_IVR),
67 };
68 
69 static 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 
85 static 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 
100 static 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 
135 static 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 
159 static 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 
182 static 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 
199 static 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 
205 static 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 
232 static 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 };
239 MODULE_DEVICE_TABLE(of, ds1803_dt_ids);
240 
241 static 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 };
248 MODULE_DEVICE_TABLE(i2c, ds1803_id);
249 
250 static struct i2c_driver ds1803_driver = {
251 	.driver = {
252 		.name	= "ds1803",
253 		.of_match_table = ds1803_dt_ids,
254 	},
255 	.probe_new	= ds1803_probe,
256 	.id_table	= ds1803_id,
257 };
258 
259 module_i2c_driver(ds1803_driver);
260 
261 MODULE_AUTHOR("Slawomir Stepien <sst@poczta.fm>");
262 MODULE_AUTHOR("Jagath Jog J <jagathjog1996@gmail.com>");
263 MODULE_DESCRIPTION("DS1803 digital potentiometer");
264 MODULE_LICENSE("GPL v2");
265