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// SPDX-License-Identifier: GPL-2.0
/*
* Generic sigma delta modulator driver
*
* Copyright (C) 2017, STMicroelectronics - All Rights Reserved
* Author: Arnaud Pouliquen <arnaud.pouliquen@st.com>.
*/
#include <linux/iio/backend.h>
#include <linux/iio/iio.h>
#include <linux/iio/triggered_buffer.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/regulator/consumer.h>
static const struct iio_info iio_sd_mod_iio_info;
static const struct iio_chan_spec iio_sd_mod_ch = {
.type = IIO_VOLTAGE,
.indexed = 1,
.scan_type = {
.sign = 'u',
.realbits = 1,
.shift = 0,
},
};
struct iio_sd_backend_priv {
struct regulator *vref;
int vref_mv;
};
static int iio_sd_mod_enable(struct iio_backend *backend)
{
struct iio_sd_backend_priv *priv = iio_backend_get_priv(backend);
if (priv->vref)
return regulator_enable(priv->vref);
return 0;
};
static void iio_sd_mod_disable(struct iio_backend *backend)
{
struct iio_sd_backend_priv *priv = iio_backend_get_priv(backend);
if (priv->vref)
regulator_disable(priv->vref);
};
static int iio_sd_mod_read(struct iio_backend *backend, struct iio_chan_spec const *chan, int *val,
int *val2, long mask)
{
struct iio_sd_backend_priv *priv = iio_backend_get_priv(backend);
switch (mask) {
case IIO_CHAN_INFO_SCALE:
*val = priv->vref_mv;
return IIO_VAL_INT;
case IIO_CHAN_INFO_OFFSET:
*val = 0;
return IIO_VAL_INT;
}
return -EOPNOTSUPP;
};
static const struct iio_backend_ops sd_backend_ops = {
.enable = iio_sd_mod_enable,
.disable = iio_sd_mod_disable,
.read_raw = iio_sd_mod_read,
};
static const struct iio_backend_info sd_backend_info = {
.name = "sd-modulator",
.ops = &sd_backend_ops,
};
static int iio_sd_mod_register(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct iio_dev *iio;
iio = devm_iio_device_alloc(dev, 0);
if (!iio)
return -ENOMEM;
iio->name = dev_name(dev);
iio->info = &iio_sd_mod_iio_info;
iio->modes = INDIO_BUFFER_HARDWARE;
iio->num_channels = 1;
iio->channels = &iio_sd_mod_ch;
platform_set_drvdata(pdev, iio);
return devm_iio_device_register(&pdev->dev, iio);
}
static int iio_sd_mod_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct regulator *vref;
struct iio_sd_backend_priv *priv;
int ret;
/* If sd modulator is not defined as an IIO backend device, fallback to legacy */
if (!device_property_present(dev, "#io-backend-cells"))
return iio_sd_mod_register(pdev);
priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
/*
* Get regulator reference if any, but don't enable regulator right now.
* Rely on enable and disable callbacks to manage regulator power.
*/
vref = devm_regulator_get_optional(dev, "vref");
if (IS_ERR(vref)) {
if (PTR_ERR(vref) != -ENODEV)
return dev_err_probe(dev, PTR_ERR(vref), "Failed to get vref\n");
} else {
/*
* Retrieve voltage right now, as regulator_get_voltage() provides it whatever
* the state of the regulator.
*/
ret = regulator_get_voltage(vref);
if (ret < 0)
return ret;
priv->vref = vref;
priv->vref_mv = ret / 1000;
}
return devm_iio_backend_register(&pdev->dev, &sd_backend_info, priv);
};
static const struct of_device_id sd_adc_of_match[] = {
{ .compatible = "sd-modulator" },
{ .compatible = "ads1201" },
{ }
};
MODULE_DEVICE_TABLE(of, sd_adc_of_match);
static struct platform_driver iio_sd_mod_adc = {
.driver = {
.name = "iio_sd_adc_mod",
.of_match_table = sd_adc_of_match,
},
.probe = iio_sd_mod_probe,
};
module_platform_driver(iio_sd_mod_adc);
MODULE_DESCRIPTION("Basic sigma delta modulator");
MODULE_AUTHOR("Arnaud Pouliquen <arnaud.pouliquen@st.com>");
MODULE_LICENSE("GPL v2");
MODULE_IMPORT_NS("IIO_BACKEND");
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