1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Industrial I/O driver for Microchip digital potentiometers
4 *
5 * Copyright (c) 2018 Chris Coffey <cmc@babblebit.net>
6 * Based on: Slawomir Stepien's code from mcp4131.c
7 *
8 * Datasheet: https://ww1.microchip.com/downloads/en/devicedoc/11195c.pdf
9 *
10 * DEVID	#Wipers	#Positions	Resistance (kOhm)
11 * mcp41010	1	256		10
12 * mcp41050	1	256		50
13 * mcp41100	1	256		100
14 * mcp42010	2	256		10
15 * mcp42050	2	256		50
16 * mcp42100	2	256		100
17 */
18
19#include <linux/cache.h>
20#include <linux/err.h>
21#include <linux/iio/iio.h>
22#include <linux/iio/types.h>
23#include <linux/module.h>
24#include <linux/mutex.h>
25#include <linux/of.h>
26#include <linux/of_device.h>
27#include <linux/spi/spi.h>
28
29#define MCP41010_MAX_WIPERS	2
30#define MCP41010_WRITE		BIT(4)
31#define MCP41010_WIPER_MAX	255
32#define MCP41010_WIPER_CHANNEL	BIT(0)
33
34struct mcp41010_cfg {
35	char name[16];
36	int wipers;
37	int kohms;
38};
39
40enum mcp41010_type {
41	MCP41010,
42	MCP41050,
43	MCP41100,
44	MCP42010,
45	MCP42050,
46	MCP42100,
47};
48
49static const struct mcp41010_cfg mcp41010_cfg[] = {
50	[MCP41010] = { .name = "mcp41010", .wipers = 1, .kohms =  10, },
51	[MCP41050] = { .name = "mcp41050", .wipers = 1, .kohms =  50, },
52	[MCP41100] = { .name = "mcp41100", .wipers = 1, .kohms = 100, },
53	[MCP42010] = { .name = "mcp42010", .wipers = 2, .kohms =  10, },
54	[MCP42050] = { .name = "mcp42050", .wipers = 2, .kohms =  50, },
55	[MCP42100] = { .name = "mcp42100", .wipers = 2, .kohms = 100, },
56};
57
58struct mcp41010_data {
59	struct spi_device *spi;
60	const struct mcp41010_cfg *cfg;
61	struct mutex lock; /* Protect write sequences */
62	unsigned int value[MCP41010_MAX_WIPERS]; /* Cache wiper values */
63	u8 buf[2] ____cacheline_aligned;
64};
65
66#define MCP41010_CHANNEL(ch) {					\
67	.type = IIO_RESISTANCE,					\
68	.indexed = 1,						\
69	.output = 1,						\
70	.channel = (ch),					\
71	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
72	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
73}
74
75static const struct iio_chan_spec mcp41010_channels[] = {
76	MCP41010_CHANNEL(0),
77	MCP41010_CHANNEL(1),
78};
79
80static int mcp41010_read_raw(struct iio_dev *indio_dev,
81			    struct iio_chan_spec const *chan,
82			    int *val, int *val2, long mask)
83{
84	struct mcp41010_data *data = iio_priv(indio_dev);
85	int channel = chan->channel;
86
87	switch (mask) {
88	case IIO_CHAN_INFO_RAW:
89		*val = data->value[channel];
90		return IIO_VAL_INT;
91
92	case IIO_CHAN_INFO_SCALE:
93		*val = 1000 * data->cfg->kohms;
94		*val2 = MCP41010_WIPER_MAX;
95		return IIO_VAL_FRACTIONAL;
96	}
97
98	return -EINVAL;
99}
100
101static int mcp41010_write_raw(struct iio_dev *indio_dev,
102			     struct iio_chan_spec const *chan,
103			     int val, int val2, long mask)
104{
105	int err;
106	struct mcp41010_data *data = iio_priv(indio_dev);
107	int channel = chan->channel;
108
109	if (mask != IIO_CHAN_INFO_RAW)
110		return -EINVAL;
111
112	if (val > MCP41010_WIPER_MAX || val < 0)
113		return -EINVAL;
114
115	mutex_lock(&data->lock);
116
117	data->buf[0] = MCP41010_WIPER_CHANNEL << channel;
118	data->buf[0] |= MCP41010_WRITE;
119	data->buf[1] = val & 0xff;
120
121	err = spi_write(data->spi, data->buf, sizeof(data->buf));
122	if (!err)
123		data->value[channel] = val;
124
125	mutex_unlock(&data->lock);
126
127	return err;
128}
129
130static const struct iio_info mcp41010_info = {
131	.read_raw = mcp41010_read_raw,
132	.write_raw = mcp41010_write_raw,
133};
134
135static int mcp41010_probe(struct spi_device *spi)
136{
137	int err;
138	struct device *dev = &spi->dev;
139	struct mcp41010_data *data;
140	struct iio_dev *indio_dev;
141
142	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
143	if (!indio_dev)
144		return -ENOMEM;
145
146	data = iio_priv(indio_dev);
147	spi_set_drvdata(spi, indio_dev);
148	data->spi = spi;
149	data->cfg = of_device_get_match_data(&spi->dev);
150	if (!data->cfg)
151		data->cfg = &mcp41010_cfg[spi_get_device_id(spi)->driver_data];
152
153	mutex_init(&data->lock);
154
155	indio_dev->info = &mcp41010_info;
156	indio_dev->channels = mcp41010_channels;
157	indio_dev->num_channels = data->cfg->wipers;
158	indio_dev->name = data->cfg->name;
159
160	err = devm_iio_device_register(dev, indio_dev);
161	if (err)
162		dev_info(&spi->dev, "Unable to register %s\n", indio_dev->name);
163
164	return err;
165}
166
167static const struct of_device_id mcp41010_match[] = {
168	{ .compatible = "microchip,mcp41010", .data = &mcp41010_cfg[MCP41010] },
169	{ .compatible = "microchip,mcp41050", .data = &mcp41010_cfg[MCP41050] },
170	{ .compatible = "microchip,mcp41100", .data = &mcp41010_cfg[MCP41100] },
171	{ .compatible = "microchip,mcp42010", .data = &mcp41010_cfg[MCP42010] },
172	{ .compatible = "microchip,mcp42050", .data = &mcp41010_cfg[MCP42050] },
173	{ .compatible = "microchip,mcp42100", .data = &mcp41010_cfg[MCP42100] },
174	{}
175};
176MODULE_DEVICE_TABLE(of, mcp41010_match);
177
178static const struct spi_device_id mcp41010_id[] = {
179	{ "mcp41010", MCP41010 },
180	{ "mcp41050", MCP41050 },
181	{ "mcp41100", MCP41100 },
182	{ "mcp42010", MCP42010 },
183	{ "mcp42050", MCP42050 },
184	{ "mcp42100", MCP42100 },
185	{}
186};
187MODULE_DEVICE_TABLE(spi, mcp41010_id);
188
189static struct spi_driver mcp41010_driver = {
190	.driver = {
191		.name	= "mcp41010",
192		.of_match_table = mcp41010_match,
193	},
194	.probe		= mcp41010_probe,
195	.id_table	= mcp41010_id,
196};
197
198module_spi_driver(mcp41010_driver);
199
200MODULE_AUTHOR("Chris Coffey <cmc@babblebit.net>");
201MODULE_DESCRIPTION("MCP41010 digital potentiometer");
202MODULE_LICENSE("GPL v2");
203