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
ds1803_read(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val)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
ds3502_read(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val)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
ds1803_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long mask)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
ds1803_write_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int val,int val2,long mask)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
ds1803_read_avail(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,const int ** vals,int * type,int * length,long mask)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
ds1803_probe(struct i2c_client * client)205 static int ds1803_probe(struct i2c_client *client)
206 {
207 struct device *dev = &client->dev;
208 struct ds1803_data *data;
209 struct iio_dev *indio_dev;
210
211 indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
212 if (!indio_dev)
213 return -ENOMEM;
214
215 i2c_set_clientdata(client, indio_dev);
216
217 data = iio_priv(indio_dev);
218 data->client = client;
219 data->cfg = i2c_get_match_data(client);
220
221 indio_dev->info = &ds1803_info;
222 indio_dev->channels = data->cfg->channels;
223 indio_dev->num_channels = data->cfg->num_channels;
224 indio_dev->name = client->name;
225
226 return devm_iio_device_register(dev, indio_dev);
227 }
228
229 static const struct of_device_id ds1803_dt_ids[] = {
230 { .compatible = "maxim,ds1803-010", .data = &ds1803_cfg[DS1803_010] },
231 { .compatible = "maxim,ds1803-050", .data = &ds1803_cfg[DS1803_050] },
232 { .compatible = "maxim,ds1803-100", .data = &ds1803_cfg[DS1803_100] },
233 { .compatible = "maxim,ds3502", .data = &ds1803_cfg[DS3502] },
234 {}
235 };
236 MODULE_DEVICE_TABLE(of, ds1803_dt_ids);
237
238 static const struct i2c_device_id ds1803_id[] = {
239 { "ds1803-010", (kernel_ulong_t)&ds1803_cfg[DS1803_010] },
240 { "ds1803-050", (kernel_ulong_t)&ds1803_cfg[DS1803_050] },
241 { "ds1803-100", (kernel_ulong_t)&ds1803_cfg[DS1803_100] },
242 { "ds3502", (kernel_ulong_t)&ds1803_cfg[DS3502] },
243 {}
244 };
245 MODULE_DEVICE_TABLE(i2c, ds1803_id);
246
247 static struct i2c_driver ds1803_driver = {
248 .driver = {
249 .name = "ds1803",
250 .of_match_table = ds1803_dt_ids,
251 },
252 .probe = ds1803_probe,
253 .id_table = ds1803_id,
254 };
255
256 module_i2c_driver(ds1803_driver);
257
258 MODULE_AUTHOR("Slawomir Stepien <sst@poczta.fm>");
259 MODULE_AUTHOR("Jagath Jog J <jagathjog1996@gmail.com>");
260 MODULE_DESCRIPTION("DS1803 digital potentiometer");
261 MODULE_LICENSE("GPL v2");
262