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(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(data->client, val);
95}
96
97static const struct iio_info mcp4018_info = {
98	.read_raw = mcp4018_read_raw,
99	.write_raw = mcp4018_write_raw,
100};
101
102static 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};
117MODULE_DEVICE_TABLE(i2c, mcp4018_id);
118
119#define MCP4018_COMPATIBLE(of_compatible, cfg) {	\
120	.compatible = of_compatible,			\
121	.data = &mcp4018_cfg[cfg],			\
122}
123
124static 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};
139MODULE_DEVICE_TABLE(of, mcp4018_of_match);
140
141static 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
172static struct i2c_driver mcp4018_driver = {
173	.driver = {
174		.name	= "mcp4018",
175		.of_match_table = mcp4018_of_match,
176	},
177	.probe_new	= mcp4018_probe,
178	.id_table	= mcp4018_id,
179};
180
181module_i2c_driver(mcp4018_driver);
182
183MODULE_AUTHOR("Peter Rosin <peda@axentia.se>");
184MODULE_DESCRIPTION("MCP4018 digital potentiometer");
185MODULE_LICENSE("GPL v2");
186