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/*
* ADC0831/ADC0832/ADC0834/ADC0838 8-bit ADC driver
*
* Copyright (c) 2016 Akinobu Mita <akinobu.mita@gmail.com>
*
* This file is subject to the terms and conditions of version 2 of
* the GNU General Public License. See the file COPYING in the main
* directory of this archive for more details.
*
* Datasheet: http://www.ti.com/lit/ds/symlink/adc0832-n.pdf
*/
#include <linux/module.h>
#include <linux/spi/spi.h>
#include <linux/iio/iio.h>
#include <linux/regulator/consumer.h>
enum {
adc0831,
adc0832,
adc0834,
adc0838,
};
struct adc0832 {
struct spi_device *spi;
struct regulator *reg;
struct mutex lock;
u8 mux_bits;
u8 tx_buf[2] ____cacheline_aligned;
u8 rx_buf[2];
};
#define ADC0832_VOLTAGE_CHANNEL(chan) \
{ \
.type = IIO_VOLTAGE, \
.indexed = 1, \
.channel = chan, \
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) \
}
#define ADC0832_VOLTAGE_CHANNEL_DIFF(chan1, chan2) \
{ \
.type = IIO_VOLTAGE, \
.indexed = 1, \
.channel = (chan1), \
.channel2 = (chan2), \
.differential = 1, \
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) \
}
static const struct iio_chan_spec adc0831_channels[] = {
ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1),
};
static const struct iio_chan_spec adc0832_channels[] = {
ADC0832_VOLTAGE_CHANNEL(0),
ADC0832_VOLTAGE_CHANNEL(1),
ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1),
ADC0832_VOLTAGE_CHANNEL_DIFF(1, 0),
};
static const struct iio_chan_spec adc0834_channels[] = {
ADC0832_VOLTAGE_CHANNEL(0),
ADC0832_VOLTAGE_CHANNEL(1),
ADC0832_VOLTAGE_CHANNEL(2),
ADC0832_VOLTAGE_CHANNEL(3),
ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1),
ADC0832_VOLTAGE_CHANNEL_DIFF(1, 0),
ADC0832_VOLTAGE_CHANNEL_DIFF(2, 3),
ADC0832_VOLTAGE_CHANNEL_DIFF(3, 2),
};
static const struct iio_chan_spec adc0838_channels[] = {
ADC0832_VOLTAGE_CHANNEL(0),
ADC0832_VOLTAGE_CHANNEL(1),
ADC0832_VOLTAGE_CHANNEL(2),
ADC0832_VOLTAGE_CHANNEL(3),
ADC0832_VOLTAGE_CHANNEL(4),
ADC0832_VOLTAGE_CHANNEL(5),
ADC0832_VOLTAGE_CHANNEL(6),
ADC0832_VOLTAGE_CHANNEL(7),
ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1),
ADC0832_VOLTAGE_CHANNEL_DIFF(1, 0),
ADC0832_VOLTAGE_CHANNEL_DIFF(2, 3),
ADC0832_VOLTAGE_CHANNEL_DIFF(3, 2),
ADC0832_VOLTAGE_CHANNEL_DIFF(4, 5),
ADC0832_VOLTAGE_CHANNEL_DIFF(5, 4),
ADC0832_VOLTAGE_CHANNEL_DIFF(6, 7),
ADC0832_VOLTAGE_CHANNEL_DIFF(7, 6),
};
static int adc0831_adc_conversion(struct adc0832 *adc)
{
struct spi_device *spi = adc->spi;
int ret;
ret = spi_read(spi, &adc->rx_buf, 2);
if (ret)
return ret;
/*
* Skip TRI-STATE and a leading zero
*/
return (adc->rx_buf[0] << 2 & 0xff) | (adc->rx_buf[1] >> 6);
}
static int adc0832_adc_conversion(struct adc0832 *adc, int channel,
bool differential)
{
struct spi_device *spi = adc->spi;
struct spi_transfer xfer = {
.tx_buf = adc->tx_buf,
.rx_buf = adc->rx_buf,
.len = 2,
};
int ret;
if (!adc->mux_bits)
return adc0831_adc_conversion(adc);
/* start bit */
adc->tx_buf[0] = 1 << (adc->mux_bits + 1);
/* single-ended or differential */
adc->tx_buf[0] |= differential ? 0 : (1 << adc->mux_bits);
/* odd / sign */
adc->tx_buf[0] |= (channel % 2) << (adc->mux_bits - 1);
/* select */
if (adc->mux_bits > 1)
adc->tx_buf[0] |= channel / 2;
/* align Data output BIT7 (MSB) to 8-bit boundary */
adc->tx_buf[0] <<= 1;
ret = spi_sync_transfer(spi, &xfer, 1);
if (ret)
return ret;
return adc->rx_buf[1];
}
static int adc0832_read_raw(struct iio_dev *iio,
struct iio_chan_spec const *channel, int *value,
int *shift, long mask)
{
struct adc0832 *adc = iio_priv(iio);
switch (mask) {
case IIO_CHAN_INFO_RAW:
mutex_lock(&adc->lock);
*value = adc0832_adc_conversion(adc, channel->channel,
channel->differential);
mutex_unlock(&adc->lock);
if (*value < 0)
return *value;
return IIO_VAL_INT;
case IIO_CHAN_INFO_SCALE:
*value = regulator_get_voltage(adc->reg);
if (*value < 0)
return *value;
/* convert regulator output voltage to mV */
*value /= 1000;
*shift = 8;
return IIO_VAL_FRACTIONAL_LOG2;
}
return -EINVAL;
}
static const struct iio_info adc0832_info = {
.read_raw = adc0832_read_raw,
.driver_module = THIS_MODULE,
};
static int adc0832_probe(struct spi_device *spi)
{
struct iio_dev *indio_dev;
struct adc0832 *adc;
int ret;
indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
if (!indio_dev)
return -ENOMEM;
adc = iio_priv(indio_dev);
adc->spi = spi;
mutex_init(&adc->lock);
indio_dev->name = spi_get_device_id(spi)->name;
indio_dev->dev.parent = &spi->dev;
indio_dev->dev.of_node = spi->dev.of_node;
indio_dev->info = &adc0832_info;
indio_dev->modes = INDIO_DIRECT_MODE;
switch (spi_get_device_id(spi)->driver_data) {
case adc0831:
adc->mux_bits = 0;
indio_dev->channels = adc0831_channels;
indio_dev->num_channels = ARRAY_SIZE(adc0831_channels);
break;
case adc0832:
adc->mux_bits = 1;
indio_dev->channels = adc0832_channels;
indio_dev->num_channels = ARRAY_SIZE(adc0832_channels);
break;
case adc0834:
adc->mux_bits = 2;
indio_dev->channels = adc0834_channels;
indio_dev->num_channels = ARRAY_SIZE(adc0834_channels);
break;
case adc0838:
adc->mux_bits = 3;
indio_dev->channels = adc0838_channels;
indio_dev->num_channels = ARRAY_SIZE(adc0838_channels);
break;
default:
return -EINVAL;
}
adc->reg = devm_regulator_get(&spi->dev, "vref");
if (IS_ERR(adc->reg))
return PTR_ERR(adc->reg);
ret = regulator_enable(adc->reg);
if (ret)
return ret;
spi_set_drvdata(spi, indio_dev);
ret = iio_device_register(indio_dev);
if (ret)
regulator_disable(adc->reg);
return ret;
}
static int adc0832_remove(struct spi_device *spi)
{
struct iio_dev *indio_dev = spi_get_drvdata(spi);
struct adc0832 *adc = iio_priv(indio_dev);
iio_device_unregister(indio_dev);
regulator_disable(adc->reg);
return 0;
}
#ifdef CONFIG_OF
static const struct of_device_id adc0832_dt_ids[] = {
{ .compatible = "ti,adc0831", },
{ .compatible = "ti,adc0832", },
{ .compatible = "ti,adc0834", },
{ .compatible = "ti,adc0838", },
{}
};
MODULE_DEVICE_TABLE(of, adc0832_dt_ids);
#endif
static const struct spi_device_id adc0832_id[] = {
{ "adc0831", adc0831 },
{ "adc0832", adc0832 },
{ "adc0834", adc0834 },
{ "adc0838", adc0838 },
{}
};
MODULE_DEVICE_TABLE(spi, adc0832_id);
static struct spi_driver adc0832_driver = {
.driver = {
.name = "adc0832",
.of_match_table = of_match_ptr(adc0832_dt_ids),
},
.probe = adc0832_probe,
.remove = adc0832_remove,
.id_table = adc0832_id,
};
module_spi_driver(adc0832_driver);
MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>");
MODULE_DESCRIPTION("ADC0831/ADC0832/ADC0834/ADC0838 driver");
MODULE_LICENSE("GPL v2");
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