1 /*
2 * Maxim Integrated DS1803 digital potentiometer driver
3 * Copyright (c) 2016 Slawomir Stepien
4 *
5 * Datasheet: https://datasheets.maximintegrated.com/en/ds/DS1803.pdf
6 *
7 * DEVID #Wipers #Positions Resistor Opts (kOhm) i2c address
8 * ds1803 2 256 10, 50, 100 0101xxx
9 *
10 * This program is free software; you can redistribute it and/or modify it
11 * under the terms of the GNU General Public License version 2 as published by
12 * the Free Software Foundation.
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/of.h>
21
22 #define DS1803_MAX_POS 255
23 #define DS1803_WRITE(chan) (0xa8 | ((chan) + 1))
24
25 enum ds1803_type {
26 DS1803_010,
27 DS1803_050,
28 DS1803_100,
29 };
30
31 struct ds1803_cfg {
32 int kohms;
33 };
34
35 static const struct ds1803_cfg ds1803_cfg[] = {
36 [DS1803_010] = { .kohms = 10, },
37 [DS1803_050] = { .kohms = 50, },
38 [DS1803_100] = { .kohms = 100, },
39 };
40
41 struct ds1803_data {
42 struct i2c_client *client;
43 const struct ds1803_cfg *cfg;
44 };
45
46 #define DS1803_CHANNEL(ch) { \
47 .type = IIO_RESISTANCE, \
48 .indexed = 1, \
49 .output = 1, \
50 .channel = (ch), \
51 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
52 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
53 }
54
55 static const struct iio_chan_spec ds1803_channels[] = {
56 DS1803_CHANNEL(0),
57 DS1803_CHANNEL(1),
58 };
59
ds1803_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long mask)60 static int ds1803_read_raw(struct iio_dev *indio_dev,
61 struct iio_chan_spec const *chan,
62 int *val, int *val2, long mask)
63 {
64 struct ds1803_data *data = iio_priv(indio_dev);
65 int pot = chan->channel;
66 int ret;
67 u8 result[ARRAY_SIZE(ds1803_channels)];
68
69 switch (mask) {
70 case IIO_CHAN_INFO_RAW:
71 ret = i2c_master_recv(data->client, result,
72 indio_dev->num_channels);
73 if (ret < 0)
74 return ret;
75
76 *val = result[pot];
77 return IIO_VAL_INT;
78
79 case IIO_CHAN_INFO_SCALE:
80 *val = 1000 * data->cfg->kohms;
81 *val2 = DS1803_MAX_POS;
82 return IIO_VAL_FRACTIONAL;
83 }
84
85 return -EINVAL;
86 }
87
ds1803_write_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int val,int val2,long mask)88 static int ds1803_write_raw(struct iio_dev *indio_dev,
89 struct iio_chan_spec const *chan,
90 int val, int val2, long mask)
91 {
92 struct ds1803_data *data = iio_priv(indio_dev);
93 int pot = chan->channel;
94
95 if (val2 != 0)
96 return -EINVAL;
97
98 switch (mask) {
99 case IIO_CHAN_INFO_RAW:
100 if (val > DS1803_MAX_POS || val < 0)
101 return -EINVAL;
102 break;
103 default:
104 return -EINVAL;
105 }
106
107 return i2c_smbus_write_byte_data(data->client, DS1803_WRITE(pot), val);
108 }
109
110 static const struct iio_info ds1803_info = {
111 .read_raw = ds1803_read_raw,
112 .write_raw = ds1803_write_raw,
113 };
114
ds1803_probe(struct i2c_client * client,const struct i2c_device_id * id)115 static int ds1803_probe(struct i2c_client *client,
116 const struct i2c_device_id *id)
117 {
118 struct device *dev = &client->dev;
119 struct ds1803_data *data;
120 struct iio_dev *indio_dev;
121
122 indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
123 if (!indio_dev)
124 return -ENOMEM;
125
126 i2c_set_clientdata(client, indio_dev);
127
128 data = iio_priv(indio_dev);
129 data->client = client;
130 data->cfg = &ds1803_cfg[id->driver_data];
131
132 indio_dev->dev.parent = dev;
133 indio_dev->info = &ds1803_info;
134 indio_dev->channels = ds1803_channels;
135 indio_dev->num_channels = ARRAY_SIZE(ds1803_channels);
136 indio_dev->name = client->name;
137
138 return devm_iio_device_register(dev, indio_dev);
139 }
140
141 #if defined(CONFIG_OF)
142 static const struct of_device_id ds1803_dt_ids[] = {
143 { .compatible = "maxim,ds1803-010", .data = &ds1803_cfg[DS1803_010] },
144 { .compatible = "maxim,ds1803-050", .data = &ds1803_cfg[DS1803_050] },
145 { .compatible = "maxim,ds1803-100", .data = &ds1803_cfg[DS1803_100] },
146 {}
147 };
148 MODULE_DEVICE_TABLE(of, ds1803_dt_ids);
149 #endif /* CONFIG_OF */
150
151 static const struct i2c_device_id ds1803_id[] = {
152 { "ds1803-010", DS1803_010 },
153 { "ds1803-050", DS1803_050 },
154 { "ds1803-100", DS1803_100 },
155 {}
156 };
157 MODULE_DEVICE_TABLE(i2c, ds1803_id);
158
159 static struct i2c_driver ds1803_driver = {
160 .driver = {
161 .name = "ds1803",
162 .of_match_table = of_match_ptr(ds1803_dt_ids),
163 },
164 .probe = ds1803_probe,
165 .id_table = ds1803_id,
166 };
167
168 module_i2c_driver(ds1803_driver);
169
170 MODULE_AUTHOR("Slawomir Stepien <sst@poczta.fm>");
171 MODULE_DESCRIPTION("DS1803 digital potentiometer");
172 MODULE_LICENSE("GPL v2");
173