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 
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 
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 
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 #define MCP4018_COMPATIBLE(of_compatible, cfg) {	\
120 	.compatible = of_compatible,			\
121 	.data = &mcp4018_cfg[cfg],			\
122 }
123 
124 static const struct of_device_id mcp4018_of_match[] = {
125 	MCP4018_COMPATIBLE("microchip,mcp4017-502", MCP4018_502),
126 	MCP4018_COMPATIBLE("microchip,mcp4017-103", MCP4018_103),
127 	MCP4018_COMPATIBLE("microchip,mcp4017-503", MCP4018_503),
128 	MCP4018_COMPATIBLE("microchip,mcp4017-104", MCP4018_104),
129 	MCP4018_COMPATIBLE("microchip,mcp4018-502", MCP4018_502),
130 	MCP4018_COMPATIBLE("microchip,mcp4018-103", MCP4018_103),
131 	MCP4018_COMPATIBLE("microchip,mcp4018-503", MCP4018_503),
132 	MCP4018_COMPATIBLE("microchip,mcp4018-104", MCP4018_104),
133 	MCP4018_COMPATIBLE("microchip,mcp4019-502", MCP4018_502),
134 	MCP4018_COMPATIBLE("microchip,mcp4019-103", MCP4018_103),
135 	MCP4018_COMPATIBLE("microchip,mcp4019-503", MCP4018_503),
136 	MCP4018_COMPATIBLE("microchip,mcp4019-104", MCP4018_104),
137 	{ /* sentinel */ }
138 };
139 MODULE_DEVICE_TABLE(of, mcp4018_of_match);
140 
141 static int mcp4018_probe(struct i2c_client *client)
142 {
143 	struct device *dev = &client->dev;
144 	struct mcp4018_data *data;
145 	struct iio_dev *indio_dev;
146 
147 	if (!i2c_check_functionality(client->adapter,
148 				     I2C_FUNC_SMBUS_BYTE)) {
149 		dev_err(dev, "SMBUS Byte transfers not supported\n");
150 		return -EOPNOTSUPP;
151 	}
152 
153 	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
154 	if (!indio_dev)
155 		return -ENOMEM;
156 	data = iio_priv(indio_dev);
157 	i2c_set_clientdata(client, indio_dev);
158 	data->client = client;
159 
160 	data->cfg = device_get_match_data(dev);
161 	if (!data->cfg)
162 		data->cfg = &mcp4018_cfg[i2c_match_id(mcp4018_id, client)->driver_data];
163 
164 	indio_dev->info = &mcp4018_info;
165 	indio_dev->channels = &mcp4018_channel;
166 	indio_dev->num_channels = 1;
167 	indio_dev->name = client->name;
168 
169 	return devm_iio_device_register(dev, indio_dev);
170 }
171 
172 static struct i2c_driver mcp4018_driver = {
173 	.driver = {
174 		.name	= "mcp4018",
175 		.of_match_table = mcp4018_of_match,
176 	},
177 	.probe		= mcp4018_probe,
178 	.id_table	= mcp4018_id,
179 };
180 
181 module_i2c_driver(mcp4018_driver);
182 
183 MODULE_AUTHOR("Peter Rosin <peda@axentia.se>");
184 MODULE_DESCRIPTION("MCP4018 digital potentiometer");
185 MODULE_LICENSE("GPL v2");
186