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// SPDX-License-Identifier: GPL-2.0
/*
* ad2s90.c simple support for the ADI Resolver to Digital Converters: AD2S90
*
* Copyright (c) 2010-2010 Analog Devices Inc.
*/
#include <linux/types.h>
#include <linux/mutex.h>
#include <linux/device.h>
#include <linux/spi/spi.h>
#include <linux/slab.h>
#include <linux/sysfs.h>
#include <linux/module.h>
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
/*
* Although chip's max frequency is 2Mhz, it needs 600ns between CS and the
* first falling edge of SCLK, so frequency should be at most 1 / (2 * 6e-7)
*/
#define AD2S90_MAX_SPI_FREQ_HZ 830000
struct ad2s90_state {
struct mutex lock; /* lock to protect rx buffer */
struct spi_device *sdev;
u8 rx[2] ____cacheline_aligned;
};
static int ad2s90_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int *val,
int *val2,
long m)
{
int ret;
struct ad2s90_state *st = iio_priv(indio_dev);
if (chan->type != IIO_ANGL)
return -EINVAL;
switch (m) {
case IIO_CHAN_INFO_SCALE:
/* 2 * Pi / 2^12 */
*val = 6283; /* mV */
*val2 = 12;
return IIO_VAL_FRACTIONAL_LOG2;
case IIO_CHAN_INFO_RAW:
mutex_lock(&st->lock);
ret = spi_read(st->sdev, st->rx, 2);
if (ret < 0) {
mutex_unlock(&st->lock);
return ret;
}
*val = (((u16)(st->rx[0])) << 4) | ((st->rx[1] & 0xF0) >> 4);
mutex_unlock(&st->lock);
return IIO_VAL_INT;
default:
break;
}
return -EINVAL;
}
static const struct iio_info ad2s90_info = {
.read_raw = ad2s90_read_raw,
};
static const struct iio_chan_spec ad2s90_chan = {
.type = IIO_ANGL,
.indexed = 1,
.channel = 0,
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
};
static int ad2s90_probe(struct spi_device *spi)
{
struct iio_dev *indio_dev;
struct ad2s90_state *st;
if (spi->max_speed_hz > AD2S90_MAX_SPI_FREQ_HZ) {
dev_err(&spi->dev, "SPI CLK, %d Hz exceeds %d Hz\n",
spi->max_speed_hz, AD2S90_MAX_SPI_FREQ_HZ);
return -EINVAL;
}
indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
if (!indio_dev)
return -ENOMEM;
st = iio_priv(indio_dev);
spi_set_drvdata(spi, indio_dev);
mutex_init(&st->lock);
st->sdev = spi;
indio_dev->info = &ad2s90_info;
indio_dev->modes = INDIO_DIRECT_MODE;
indio_dev->channels = &ad2s90_chan;
indio_dev->num_channels = 1;
indio_dev->name = spi_get_device_id(spi)->name;
return devm_iio_device_register(indio_dev->dev.parent, indio_dev);
}
static const struct of_device_id ad2s90_of_match[] = {
{ .compatible = "adi,ad2s90", },
{}
};
MODULE_DEVICE_TABLE(of, ad2s90_of_match);
static const struct spi_device_id ad2s90_id[] = {
{ "ad2s90" },
{}
};
MODULE_DEVICE_TABLE(spi, ad2s90_id);
static struct spi_driver ad2s90_driver = {
.driver = {
.name = "ad2s90",
.of_match_table = ad2s90_of_match,
},
.probe = ad2s90_probe,
.id_table = ad2s90_id,
};
module_spi_driver(ad2s90_driver);
MODULE_AUTHOR("Graff Yang <graff.yang@gmail.com>");
MODULE_DESCRIPTION("Analog Devices AD2S90 Resolver to Digital SPI driver");
MODULE_LICENSE("GPL v2");
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