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// SPDX-License-Identifier: GPL-2.0
/*
* Industrial I/O driver for Microchip digital potentiometers
*
* Copyright (c) 2018 Chris Coffey <cmc@babblebit.net>
* Based on: Slawomir Stepien's code from mcp4131.c
*
* Datasheet: https://ww1.microchip.com/downloads/en/devicedoc/11195c.pdf
*
* DEVID #Wipers #Positions Resistance (kOhm)
* mcp41010 1 256 10
* mcp41050 1 256 50
* mcp41100 1 256 100
* mcp42010 2 256 10
* mcp42050 2 256 50
* mcp42100 2 256 100
*/
#include <linux/cache.h>
#include <linux/err.h>
#include <linux/iio/iio.h>
#include <linux/iio/types.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/spi/spi.h>
#define MCP41010_MAX_WIPERS 2
#define MCP41010_WRITE BIT(4)
#define MCP41010_WIPER_MAX 255
#define MCP41010_WIPER_CHANNEL BIT(0)
struct mcp41010_cfg {
char name[16];
int wipers;
int kohms;
};
enum mcp41010_type {
MCP41010,
MCP41050,
MCP41100,
MCP42010,
MCP42050,
MCP42100,
};
static const struct mcp41010_cfg mcp41010_cfg[] = {
[MCP41010] = { .name = "mcp41010", .wipers = 1, .kohms = 10, },
[MCP41050] = { .name = "mcp41050", .wipers = 1, .kohms = 50, },
[MCP41100] = { .name = "mcp41100", .wipers = 1, .kohms = 100, },
[MCP42010] = { .name = "mcp42010", .wipers = 2, .kohms = 10, },
[MCP42050] = { .name = "mcp42050", .wipers = 2, .kohms = 50, },
[MCP42100] = { .name = "mcp42100", .wipers = 2, .kohms = 100, },
};
struct mcp41010_data {
struct spi_device *spi;
const struct mcp41010_cfg *cfg;
struct mutex lock; /* Protect write sequences */
unsigned int value[MCP41010_MAX_WIPERS]; /* Cache wiper values */
u8 buf[2] ____cacheline_aligned;
};
#define MCP41010_CHANNEL(ch) { \
.type = IIO_RESISTANCE, \
.indexed = 1, \
.output = 1, \
.channel = (ch), \
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
}
static const struct iio_chan_spec mcp41010_channels[] = {
MCP41010_CHANNEL(0),
MCP41010_CHANNEL(1),
};
static int mcp41010_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int *val, int *val2, long mask)
{
struct mcp41010_data *data = iio_priv(indio_dev);
int channel = chan->channel;
switch (mask) {
case IIO_CHAN_INFO_RAW:
*val = data->value[channel];
return IIO_VAL_INT;
case IIO_CHAN_INFO_SCALE:
*val = 1000 * data->cfg->kohms;
*val2 = MCP41010_WIPER_MAX;
return IIO_VAL_FRACTIONAL;
}
return -EINVAL;
}
static int mcp41010_write_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int val, int val2, long mask)
{
int err;
struct mcp41010_data *data = iio_priv(indio_dev);
int channel = chan->channel;
if (mask != IIO_CHAN_INFO_RAW)
return -EINVAL;
if (val > MCP41010_WIPER_MAX || val < 0)
return -EINVAL;
mutex_lock(&data->lock);
data->buf[0] = MCP41010_WIPER_CHANNEL << channel;
data->buf[0] |= MCP41010_WRITE;
data->buf[1] = val & 0xff;
err = spi_write(data->spi, data->buf, sizeof(data->buf));
if (!err)
data->value[channel] = val;
mutex_unlock(&data->lock);
return err;
}
static const struct iio_info mcp41010_info = {
.read_raw = mcp41010_read_raw,
.write_raw = mcp41010_write_raw,
};
static int mcp41010_probe(struct spi_device *spi)
{
int err;
struct device *dev = &spi->dev;
struct mcp41010_data *data;
struct iio_dev *indio_dev;
indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
if (!indio_dev)
return -ENOMEM;
data = iio_priv(indio_dev);
spi_set_drvdata(spi, indio_dev);
data->spi = spi;
data->cfg = of_device_get_match_data(&spi->dev);
if (!data->cfg)
data->cfg = &mcp41010_cfg[spi_get_device_id(spi)->driver_data];
mutex_init(&data->lock);
indio_dev->info = &mcp41010_info;
indio_dev->channels = mcp41010_channels;
indio_dev->num_channels = data->cfg->wipers;
indio_dev->name = data->cfg->name;
err = devm_iio_device_register(dev, indio_dev);
if (err)
dev_info(&spi->dev, "Unable to register %s\n", indio_dev->name);
return err;
}
static const struct of_device_id mcp41010_match[] = {
{ .compatible = "microchip,mcp41010", .data = &mcp41010_cfg[MCP41010] },
{ .compatible = "microchip,mcp41050", .data = &mcp41010_cfg[MCP41050] },
{ .compatible = "microchip,mcp41100", .data = &mcp41010_cfg[MCP41100] },
{ .compatible = "microchip,mcp42010", .data = &mcp41010_cfg[MCP42010] },
{ .compatible = "microchip,mcp42050", .data = &mcp41010_cfg[MCP42050] },
{ .compatible = "microchip,mcp42100", .data = &mcp41010_cfg[MCP42100] },
{}
};
MODULE_DEVICE_TABLE(of, mcp41010_match);
static const struct spi_device_id mcp41010_id[] = {
{ "mcp41010", MCP41010 },
{ "mcp41050", MCP41050 },
{ "mcp41100", MCP41100 },
{ "mcp42010", MCP42010 },
{ "mcp42050", MCP42050 },
{ "mcp42100", MCP42100 },
{}
};
MODULE_DEVICE_TABLE(spi, mcp41010_id);
static struct spi_driver mcp41010_driver = {
.driver = {
.name = "mcp41010",
.of_match_table = mcp41010_match,
},
.probe = mcp41010_probe,
.id_table = mcp41010_id,
};
module_spi_driver(mcp41010_driver);
MODULE_AUTHOR("Chris Coffey <cmc@babblebit.net>");
MODULE_DESCRIPTION("MCP41010 digital potentiometer");
MODULE_LICENSE("GPL v2");
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