1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Industrial I/O driver for Microchip digital potentiometers
4 * Copyright (c) 2018 Axentia Technologies AB
5 * Author: Peter Rosin <peda@axentia.se>
6 *
7 * Datasheet: http://www.microchip.com/downloads/en/DeviceDoc/22147a.pdf
8 *
9 * DEVID #Wipers #Positions Resistor Opts (kOhm)
10 * mcp4017 1 128 5, 10, 50, 100
11 * mcp4018 1 128 5, 10, 50, 100
12 * mcp4019 1 128 5, 10, 50, 100
13 */
14
15#include <linux/err.h>
16#include <linux/i2c.h>
17#include <linux/iio/iio.h>
18#include <linux/module.h>
19#include <linux/mod_devicetable.h>
20#include <linux/property.h>
21
22#define MCP4018_WIPER_MAX 127
23
24struct mcp4018_cfg {
25 int kohms;
26};
27
28enum mcp4018_type {
29 MCP4018_502,
30 MCP4018_103,
31 MCP4018_503,
32 MCP4018_104,
33};
34
35static const struct mcp4018_cfg mcp4018_cfg[] = {
36 [MCP4018_502] = { .kohms = 5, },
37 [MCP4018_103] = { .kohms = 10, },
38 [MCP4018_503] = { .kohms = 50, },
39 [MCP4018_104] = { .kohms = 100, },
40};
41
42struct mcp4018_data {
43 struct i2c_client *client;
44 const struct mcp4018_cfg *cfg;
45};
46
47static const struct iio_chan_spec mcp4018_channel = {
48 .type = IIO_RESISTANCE,
49 .indexed = 1,
50 .output = 1,
51 .channel = 0,
52 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
53 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
54};
55
56static int mcp4018_read_raw(struct iio_dev *indio_dev,
57 struct iio_chan_spec const *chan,
58 int *val, int *val2, long mask)
59{
60 struct mcp4018_data *data = iio_priv(indio_dev);
61 s32 ret;
62
63 switch (mask) {
64 case IIO_CHAN_INFO_RAW:
65 ret = i2c_smbus_read_byte(client: data->client);
66 if (ret < 0)
67 return ret;
68 *val = ret;
69 return IIO_VAL_INT;
70 case IIO_CHAN_INFO_SCALE:
71 *val = 1000 * data->cfg->kohms;
72 *val2 = MCP4018_WIPER_MAX;
73 return IIO_VAL_FRACTIONAL;
74 }
75
76 return -EINVAL;
77}
78
79static int mcp4018_write_raw(struct iio_dev *indio_dev,
80 struct iio_chan_spec const *chan,
81 int val, int val2, long mask)
82{
83 struct mcp4018_data *data = iio_priv(indio_dev);
84
85 switch (mask) {
86 case IIO_CHAN_INFO_RAW:
87 if (val > MCP4018_WIPER_MAX || val < 0)
88 return -EINVAL;
89 break;
90 default:
91 return -EINVAL;
92 }
93
94 return i2c_smbus_write_byte(client: data->client, value: val);
95}
96
97static const struct iio_info mcp4018_info = {
98 .read_raw = mcp4018_read_raw,
99 .write_raw = mcp4018_write_raw,
100};
101
102#define MCP4018_ID_TABLE(_name, cfg) { \
103 .name = _name, \
104 .driver_data = (kernel_ulong_t)&mcp4018_cfg[cfg], \
105}
106
107static const struct i2c_device_id mcp4018_id[] = {
108 MCP4018_ID_TABLE("mcp4017-502", MCP4018_502),
109 MCP4018_ID_TABLE("mcp4017-103", MCP4018_103),
110 MCP4018_ID_TABLE("mcp4017-503", MCP4018_503),
111 MCP4018_ID_TABLE("mcp4017-104", MCP4018_104),
112 MCP4018_ID_TABLE("mcp4018-502", MCP4018_502),
113 MCP4018_ID_TABLE("mcp4018-103", MCP4018_103),
114 MCP4018_ID_TABLE("mcp4018-503", MCP4018_503),
115 MCP4018_ID_TABLE("mcp4018-104", MCP4018_104),
116 MCP4018_ID_TABLE("mcp4019-502", MCP4018_502),
117 MCP4018_ID_TABLE("mcp4019-103", MCP4018_103),
118 MCP4018_ID_TABLE("mcp4019-503", MCP4018_503),
119 MCP4018_ID_TABLE("mcp4019-104", MCP4018_104),
120 { /* sentinel */ }
121};
122MODULE_DEVICE_TABLE(i2c, mcp4018_id);
123
124#define MCP4018_COMPATIBLE(of_compatible, cfg) { \
125 .compatible = of_compatible, \
126 .data = &mcp4018_cfg[cfg], \
127}
128
129static const struct of_device_id mcp4018_of_match[] = {
130 MCP4018_COMPATIBLE("microchip,mcp4017-502", MCP4018_502),
131 MCP4018_COMPATIBLE("microchip,mcp4017-103", MCP4018_103),
132 MCP4018_COMPATIBLE("microchip,mcp4017-503", MCP4018_503),
133 MCP4018_COMPATIBLE("microchip,mcp4017-104", MCP4018_104),
134 MCP4018_COMPATIBLE("microchip,mcp4018-502", MCP4018_502),
135 MCP4018_COMPATIBLE("microchip,mcp4018-103", MCP4018_103),
136 MCP4018_COMPATIBLE("microchip,mcp4018-503", MCP4018_503),
137 MCP4018_COMPATIBLE("microchip,mcp4018-104", MCP4018_104),
138 MCP4018_COMPATIBLE("microchip,mcp4019-502", MCP4018_502),
139 MCP4018_COMPATIBLE("microchip,mcp4019-103", MCP4018_103),
140 MCP4018_COMPATIBLE("microchip,mcp4019-503", MCP4018_503),
141 MCP4018_COMPATIBLE("microchip,mcp4019-104", MCP4018_104),
142 { /* sentinel */ }
143};
144MODULE_DEVICE_TABLE(of, mcp4018_of_match);
145
146static int mcp4018_probe(struct i2c_client *client)
147{
148 struct device *dev = &client->dev;
149 struct mcp4018_data *data;
150 struct iio_dev *indio_dev;
151
152 if (!i2c_check_functionality(adap: client->adapter,
153 I2C_FUNC_SMBUS_BYTE)) {
154 dev_err(dev, "SMBUS Byte transfers not supported\n");
155 return -EOPNOTSUPP;
156 }
157
158 indio_dev = devm_iio_device_alloc(parent: dev, sizeof_priv: sizeof(*data));
159 if (!indio_dev)
160 return -ENOMEM;
161 data = iio_priv(indio_dev);
162 i2c_set_clientdata(client, data: indio_dev);
163 data->client = client;
164
165 data->cfg = i2c_get_match_data(client);
166
167 indio_dev->info = &mcp4018_info;
168 indio_dev->channels = &mcp4018_channel;
169 indio_dev->num_channels = 1;
170 indio_dev->name = client->name;
171
172 return devm_iio_device_register(dev, indio_dev);
173}
174
175static struct i2c_driver mcp4018_driver = {
176 .driver = {
177 .name = "mcp4018",
178 .of_match_table = mcp4018_of_match,
179 },
180 .probe = mcp4018_probe,
181 .id_table = mcp4018_id,
182};
183
184module_i2c_driver(mcp4018_driver);
185
186MODULE_AUTHOR("Peter Rosin <peda@axentia.se>");
187MODULE_DESCRIPTION("MCP4018 digital potentiometer");
188MODULE_LICENSE("GPL v2");
189

source code of linux/drivers/iio/potentiometer/mcp4018.c