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/*
* max5487.c - Support for MAX5487, MAX5488, MAX5489 digital potentiometers
*
* Copyright (C) 2016 Cristina-Gabriela Moraru <cristina.moraru09@gmail.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
*/
#include <linux/module.h>
#include <linux/spi/spi.h>
#include <linux/acpi.h>
#include <linux/iio/sysfs.h>
#include <linux/iio/iio.h>
#define MAX5487_WRITE_WIPER_A (0x01 << 8)
#define MAX5487_WRITE_WIPER_B (0x02 << 8)
/* copy both wiper regs to NV regs */
#define MAX5487_COPY_AB_TO_NV (0x23 << 8)
/* copy both NV regs to wiper regs */
#define MAX5487_COPY_NV_TO_AB (0x33 << 8)
#define MAX5487_MAX_POS 255
struct max5487_data {
struct spi_device *spi;
int kohms;
};
#define MAX5487_CHANNEL(ch, addr) { \
.type = IIO_RESISTANCE, \
.indexed = 1, \
.output = 1, \
.channel = ch, \
.address = addr, \
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
}
static const struct iio_chan_spec max5487_channels[] = {
MAX5487_CHANNEL(0, MAX5487_WRITE_WIPER_A),
MAX5487_CHANNEL(1, MAX5487_WRITE_WIPER_B),
};
static int max5487_write_cmd(struct spi_device *spi, u16 cmd)
{
return spi_write(spi, (const void *) &cmd, sizeof(u16));
}
static int max5487_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int *val, int *val2, long mask)
{
struct max5487_data *data = iio_priv(indio_dev);
if (mask != IIO_CHAN_INFO_SCALE)
return -EINVAL;
*val = 1000 * data->kohms;
*val2 = MAX5487_MAX_POS;
return IIO_VAL_FRACTIONAL;
}
static int max5487_write_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int val, int val2, long mask)
{
struct max5487_data *data = iio_priv(indio_dev);
if (mask != IIO_CHAN_INFO_RAW)
return -EINVAL;
if (val < 0 || val > MAX5487_MAX_POS)
return -EINVAL;
return max5487_write_cmd(data->spi, chan->address | val);
}
static const struct iio_info max5487_info = {
.read_raw = max5487_read_raw,
.write_raw = max5487_write_raw,
};
static int max5487_spi_probe(struct spi_device *spi)
{
struct iio_dev *indio_dev;
struct max5487_data *data;
const struct spi_device_id *id = spi_get_device_id(spi);
int ret;
indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*data));
if (!indio_dev)
return -ENOMEM;
dev_set_drvdata(&spi->dev, indio_dev);
data = iio_priv(indio_dev);
data->spi = spi;
data->kohms = id->driver_data;
indio_dev->info = &max5487_info;
indio_dev->name = id->name;
indio_dev->dev.parent = &spi->dev;
indio_dev->modes = INDIO_DIRECT_MODE;
indio_dev->channels = max5487_channels;
indio_dev->num_channels = ARRAY_SIZE(max5487_channels);
/* restore both wiper regs from NV regs */
ret = max5487_write_cmd(data->spi, MAX5487_COPY_NV_TO_AB);
if (ret < 0)
return ret;
return iio_device_register(indio_dev);
}
static int max5487_spi_remove(struct spi_device *spi)
{
struct iio_dev *indio_dev = dev_get_drvdata(&spi->dev);
iio_device_unregister(indio_dev);
/* save both wiper regs to NV regs */
return max5487_write_cmd(spi, MAX5487_COPY_AB_TO_NV);
}
static const struct spi_device_id max5487_id[] = {
{ "MAX5487", 10 },
{ "MAX5488", 50 },
{ "MAX5489", 100 },
{ }
};
MODULE_DEVICE_TABLE(spi, max5487_id);
static const struct acpi_device_id max5487_acpi_match[] = {
{ "MAX5487", 10 },
{ "MAX5488", 50 },
{ "MAX5489", 100 },
{ },
};
MODULE_DEVICE_TABLE(acpi, max5487_acpi_match);
static struct spi_driver max5487_driver = {
.driver = {
.name = "max5487",
.acpi_match_table = ACPI_PTR(max5487_acpi_match),
},
.id_table = max5487_id,
.probe = max5487_spi_probe,
.remove = max5487_spi_remove
};
module_spi_driver(max5487_driver);
MODULE_AUTHOR("Cristina-Gabriela Moraru <cristina.moraru09@gmail.com>");
MODULE_DESCRIPTION("max5487 SPI driver");
MODULE_LICENSE("GPL v2");
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