mcp4018.c

  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
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	{ }
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	{ }
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(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(dev, sizeof(*data));
159	if (!indio_dev)
160		return -ENOMEM;
161	data = iio_priv(indio_dev);
162	i2c_set_clientdata(client, 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");