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/of.h>
20 #include <linux/of_device.h>
21
22 #define MCP4018_WIPER_MAX 127
23
24 struct mcp4018_cfg {
25 int kohms;
26 };
27
28 enum mcp4018_type {
29 MCP4018_502,
30 MCP4018_103,
31 MCP4018_503,
32 MCP4018_104,
33 };
34
35 static 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
42 struct mcp4018_data {
43 struct i2c_client *client;
44 const struct mcp4018_cfg *cfg;
45 };
46
47 static 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
mcp4018_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long mask)56 static 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(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
mcp4018_write_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int val,int val2,long mask)79 static 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(data->client, val);
95 }
96
97 static const struct iio_info mcp4018_info = {
98 .read_raw = mcp4018_read_raw,
99 .write_raw = mcp4018_write_raw,
100 };
101
102 static const struct i2c_device_id mcp4018_id[] = {
103 { "mcp4017-502", MCP4018_502 },
104 { "mcp4017-103", MCP4018_103 },
105 { "mcp4017-503", MCP4018_503 },
106 { "mcp4017-104", MCP4018_104 },
107 { "mcp4018-502", MCP4018_502 },
108 { "mcp4018-103", MCP4018_103 },
109 { "mcp4018-503", MCP4018_503 },
110 { "mcp4018-104", MCP4018_104 },
111 { "mcp4019-502", MCP4018_502 },
112 { "mcp4019-103", MCP4018_103 },
113 { "mcp4019-503", MCP4018_503 },
114 { "mcp4019-104", MCP4018_104 },
115 {}
116 };
117 MODULE_DEVICE_TABLE(i2c, mcp4018_id);
118
119 #ifdef CONFIG_OF
120
121 #define MCP4018_COMPATIBLE(of_compatible, cfg) { \
122 .compatible = of_compatible, \
123 .data = &mcp4018_cfg[cfg], \
124 }
125
126 static const struct of_device_id mcp4018_of_match[] = {
127 MCP4018_COMPATIBLE("microchip,mcp4017-502", MCP4018_502),
128 MCP4018_COMPATIBLE("microchip,mcp4017-103", MCP4018_103),
129 MCP4018_COMPATIBLE("microchip,mcp4017-503", MCP4018_503),
130 MCP4018_COMPATIBLE("microchip,mcp4017-104", MCP4018_104),
131 MCP4018_COMPATIBLE("microchip,mcp4018-502", MCP4018_502),
132 MCP4018_COMPATIBLE("microchip,mcp4018-103", MCP4018_103),
133 MCP4018_COMPATIBLE("microchip,mcp4018-503", MCP4018_503),
134 MCP4018_COMPATIBLE("microchip,mcp4018-104", MCP4018_104),
135 MCP4018_COMPATIBLE("microchip,mcp4019-502", MCP4018_502),
136 MCP4018_COMPATIBLE("microchip,mcp4019-103", MCP4018_103),
137 MCP4018_COMPATIBLE("microchip,mcp4019-503", MCP4018_503),
138 MCP4018_COMPATIBLE("microchip,mcp4019-104", MCP4018_104),
139 { /* sentinel */ }
140 };
141 MODULE_DEVICE_TABLE(of, mcp4018_of_match);
142
143 #endif
144
mcp4018_probe(struct i2c_client * client)145 static int mcp4018_probe(struct i2c_client *client)
146 {
147 struct device *dev = &client->dev;
148 struct mcp4018_data *data;
149 struct iio_dev *indio_dev;
150
151 if (!i2c_check_functionality(client->adapter,
152 I2C_FUNC_SMBUS_BYTE)) {
153 dev_err(dev, "SMBUS Byte transfers not supported\n");
154 return -EOPNOTSUPP;
155 }
156
157 indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
158 if (!indio_dev)
159 return -ENOMEM;
160 data = iio_priv(indio_dev);
161 i2c_set_clientdata(client, indio_dev);
162 data->client = client;
163
164 data->cfg = of_device_get_match_data(dev);
165 if (!data->cfg)
166 data->cfg = &mcp4018_cfg[i2c_match_id(mcp4018_id, client)->driver_data];
167
168 indio_dev->dev.parent = dev;
169 indio_dev->info = &mcp4018_info;
170 indio_dev->channels = &mcp4018_channel;
171 indio_dev->num_channels = 1;
172 indio_dev->name = client->name;
173
174 return devm_iio_device_register(dev, indio_dev);
175 }
176
177 static struct i2c_driver mcp4018_driver = {
178 .driver = {
179 .name = "mcp4018",
180 .of_match_table = of_match_ptr(mcp4018_of_match),
181 },
182 .probe_new = mcp4018_probe,
183 .id_table = mcp4018_id,
184 };
185
186 module_i2c_driver(mcp4018_driver);
187
188 MODULE_AUTHOR("Peter Rosin <peda@axentia.se>");
189 MODULE_DESCRIPTION("MCP4018 digital potentiometer");
190 MODULE_LICENSE("GPL v2");
191
