1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Maxim Integrated DS1803 digital potentiometer driver
4  * Copyright (c) 2016 Slawomir Stepien
5  *
6  * Datasheet: https://datasheets.maximintegrated.com/en/ds/DS1803.pdf
7  *
8  * DEVID	#Wipers	#Positions	Resistor Opts (kOhm)	i2c address
9  * ds1803	2	256		10, 50, 100		0101xxx
10  */
11 
12 #include <linux/err.h>
13 #include <linux/export.h>
14 #include <linux/i2c.h>
15 #include <linux/iio/iio.h>
16 #include <linux/module.h>
17 #include <linux/of.h>
18 
19 #define DS1803_MAX_POS		255
20 #define DS1803_WRITE(chan)	(0xa8 | ((chan) + 1))
21 
22 enum ds1803_type {
23 	DS1803_010,
24 	DS1803_050,
25 	DS1803_100,
26 };
27 
28 struct ds1803_cfg {
29 	int kohms;
30 };
31 
32 static const struct ds1803_cfg ds1803_cfg[] = {
33 	[DS1803_010] = { .kohms =  10, },
34 	[DS1803_050] = { .kohms =  50, },
35 	[DS1803_100] = { .kohms = 100, },
36 };
37 
38 struct ds1803_data {
39 	struct i2c_client *client;
40 	const struct ds1803_cfg *cfg;
41 };
42 
43 #define DS1803_CHANNEL(ch) {					\
44 	.type = IIO_RESISTANCE,					\
45 	.indexed = 1,						\
46 	.output = 1,						\
47 	.channel = (ch),					\
48 	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
49 	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
50 }
51 
52 static const struct iio_chan_spec ds1803_channels[] = {
53 	DS1803_CHANNEL(0),
54 	DS1803_CHANNEL(1),
55 };
56 
57 static int ds1803_read_raw(struct iio_dev *indio_dev,
58 			    struct iio_chan_spec const *chan,
59 			    int *val, int *val2, long mask)
60 {
61 	struct ds1803_data *data = iio_priv(indio_dev);
62 	int pot = chan->channel;
63 	int ret;
64 	u8 result[ARRAY_SIZE(ds1803_channels)];
65 
66 	switch (mask) {
67 	case IIO_CHAN_INFO_RAW:
68 		ret = i2c_master_recv(data->client, result,
69 				indio_dev->num_channels);
70 		if (ret < 0)
71 			return ret;
72 
73 		*val = result[pot];
74 		return IIO_VAL_INT;
75 
76 	case IIO_CHAN_INFO_SCALE:
77 		*val = 1000 * data->cfg->kohms;
78 		*val2 = DS1803_MAX_POS;
79 		return IIO_VAL_FRACTIONAL;
80 	}
81 
82 	return -EINVAL;
83 }
84 
85 static int ds1803_write_raw(struct iio_dev *indio_dev,
86 			     struct iio_chan_spec const *chan,
87 			     int val, int val2, long mask)
88 {
89 	struct ds1803_data *data = iio_priv(indio_dev);
90 	int pot = chan->channel;
91 
92 	if (val2 != 0)
93 		return -EINVAL;
94 
95 	switch (mask) {
96 	case IIO_CHAN_INFO_RAW:
97 		if (val > DS1803_MAX_POS || val < 0)
98 			return -EINVAL;
99 		break;
100 	default:
101 		return -EINVAL;
102 	}
103 
104 	return i2c_smbus_write_byte_data(data->client, DS1803_WRITE(pot), val);
105 }
106 
107 static const struct iio_info ds1803_info = {
108 	.read_raw = ds1803_read_raw,
109 	.write_raw = ds1803_write_raw,
110 };
111 
112 static int ds1803_probe(struct i2c_client *client,
113 			 const struct i2c_device_id *id)
114 {
115 	struct device *dev = &client->dev;
116 	struct ds1803_data *data;
117 	struct iio_dev *indio_dev;
118 
119 	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
120 	if (!indio_dev)
121 		return -ENOMEM;
122 
123 	i2c_set_clientdata(client, indio_dev);
124 
125 	data = iio_priv(indio_dev);
126 	data->client = client;
127 	data->cfg = &ds1803_cfg[id->driver_data];
128 
129 	indio_dev->info = &ds1803_info;
130 	indio_dev->channels = ds1803_channels;
131 	indio_dev->num_channels = ARRAY_SIZE(ds1803_channels);
132 	indio_dev->name = client->name;
133 
134 	return devm_iio_device_register(dev, indio_dev);
135 }
136 
137 #if defined(CONFIG_OF)
138 static const struct of_device_id ds1803_dt_ids[] = {
139 	{ .compatible = "maxim,ds1803-010", .data = &ds1803_cfg[DS1803_010] },
140 	{ .compatible = "maxim,ds1803-050", .data = &ds1803_cfg[DS1803_050] },
141 	{ .compatible = "maxim,ds1803-100", .data = &ds1803_cfg[DS1803_100] },
142 	{}
143 };
144 MODULE_DEVICE_TABLE(of, ds1803_dt_ids);
145 #endif /* CONFIG_OF */
146 
147 static const struct i2c_device_id ds1803_id[] = {
148 	{ "ds1803-010", DS1803_010 },
149 	{ "ds1803-050", DS1803_050 },
150 	{ "ds1803-100", DS1803_100 },
151 	{}
152 };
153 MODULE_DEVICE_TABLE(i2c, ds1803_id);
154 
155 static struct i2c_driver ds1803_driver = {
156 	.driver = {
157 		.name	= "ds1803",
158 		.of_match_table = of_match_ptr(ds1803_dt_ids),
159 	},
160 	.probe		= ds1803_probe,
161 	.id_table	= ds1803_id,
162 };
163 
164 module_i2c_driver(ds1803_driver);
165 
166 MODULE_AUTHOR("Slawomir Stepien <sst@poczta.fm>");
167 MODULE_DESCRIPTION("DS1803 digital potentiometer");
168 MODULE_LICENSE("GPL v2");
169