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iio: adc: Add driver for the TI ADS8344 A/DC chips 

This adds support for the Texas Instruments ADS8344 ADC chip. This chip
has a 16-bit 8-Channel ADC and is access directly through SPI.

Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
hifive-unleashed-5.2
Gregory CLEMENT 2019-04-12 11:15:37 +02:00 committed by Jonathan Cameron
parent 65c7a3d2cf
commit 8dd2d7c0fe
3 changed files with 215 additions and 0 deletions
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10
drivers/iio/adc/Kconfig
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@ -979,6 +979,16 @@ config TI_ADS7950
To compile this driver as a module, choose M here: the
module will be called ti-ads7950.
config TI_ADS8344
tristate "Texas Instruments ADS8344"
depends on SPI && OF
help
If you say yes here you get support for Texas Instruments ADS8344
ADC chips
This driver can also be built as a module. If so, the module will be
called ti-ads8344.
config TI_ADS8688
tristate "Texas Instruments ADS8688"
depends on SPI && OF

1
drivers/iio/adc/Makefile
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@ -88,6 +88,7 @@ obj-$(CONFIG_TI_ADC128S052) += ti-adc128s052.o
obj-$(CONFIG_TI_ADC161S626) += ti-adc161s626.o
obj-$(CONFIG_TI_ADS1015) += ti-ads1015.o
obj-$(CONFIG_TI_ADS7950) += ti-ads7950.o
obj-$(CONFIG_TI_ADS8344) += ti-ads8344.o
obj-$(CONFIG_TI_ADS8688) += ti-ads8688.o
obj-$(CONFIG_TI_ADS124S08) += ti-ads124s08.o
obj-$(CONFIG_TI_AM335X_ADC) += ti_am335x_adc.o

204
drivers/iio/adc/ti-ads8344.c 100644
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@ -0,0 +1,204 @@
// SPDX-License-Identifier: GPL-2.0+
/*
* ADS8344 16-bit 8-Channel ADC driver
*
* Author: Gregory CLEMENT <gregory.clement@bootlin.com>
*
* Datasheet: http://www.ti.com/lit/ds/symlink/ads8344.pdf
*/
#include <linux/delay.h>
#include <linux/iio/buffer.h>
#include <linux/iio/iio.h>
#include <linux/module.h>
#include <linux/regulator/consumer.h>
#include <linux/spi/spi.h>
#define ADS8344_START BIT(7)
#define ADS8344_SINGLE_END BIT(2)
#define ADS8344_CHANNEL(channel) ((channel) << 4)
#define ADS8344_CLOCK_INTERNAL 0x2 /* PD1 = 1 and PD0 = 0 */
struct ads8344 {
struct spi_device *spi;
struct regulator *reg;
/*
* Lock protecting access to adc->tx_buff and rx_buff,
* especially from concurrent read on sysfs file.
*/
struct mutex lock;
u8 tx_buf ____cacheline_aligned;
u16 rx_buf;
};
#define ADS8344_VOLTAGE_CHANNEL(chan, si) \
{ \
.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 ADS8344_VOLTAGE_CHANNEL_DIFF(chan1, chan2, si) \
{ \
.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 ads8344_channels[] = {
ADS8344_VOLTAGE_CHANNEL(0, 0),
ADS8344_VOLTAGE_CHANNEL(1, 4),
ADS8344_VOLTAGE_CHANNEL(2, 1),
ADS8344_VOLTAGE_CHANNEL(3, 5),
ADS8344_VOLTAGE_CHANNEL(4, 2),
ADS8344_VOLTAGE_CHANNEL(5, 6),
ADS8344_VOLTAGE_CHANNEL(6, 3),
ADS8344_VOLTAGE_CHANNEL(7, 7),
ADS8344_VOLTAGE_CHANNEL_DIFF(0, 1, 8),
ADS8344_VOLTAGE_CHANNEL_DIFF(2, 3, 9),
ADS8344_VOLTAGE_CHANNEL_DIFF(4, 5, 10),
ADS8344_VOLTAGE_CHANNEL_DIFF(6, 7, 11),
ADS8344_VOLTAGE_CHANNEL_DIFF(1, 0, 12),
ADS8344_VOLTAGE_CHANNEL_DIFF(3, 2, 13),
ADS8344_VOLTAGE_CHANNEL_DIFF(5, 4, 14),
ADS8344_VOLTAGE_CHANNEL_DIFF(7, 6, 15),
};
static int ads8344_adc_conversion(struct ads8344 *adc, int channel,
bool differential)
{
struct spi_device *spi = adc->spi;
int ret;
adc->tx_buf = ADS8344_START;
if (!differential)
adc->tx_buf |= ADS8344_SINGLE_END;
adc->tx_buf |= ADS8344_CHANNEL(channel);
adc->tx_buf |= ADS8344_CLOCK_INTERNAL;
ret = spi_write(spi, &adc->tx_buf, 1);
if (ret)
return ret;
udelay(9);
ret = spi_read(spi, &adc->rx_buf, 2);
if (ret)
return ret;
return adc->rx_buf;
}
static int ads8344_read_raw(struct iio_dev *iio,
struct iio_chan_spec const *channel, int *value,
int *shift, long mask)
{
struct ads8344 *adc = iio_priv(iio);
switch (mask) {
case IIO_CHAN_INFO_RAW:
mutex_lock(&adc->lock);
*value = ads8344_adc_conversion(adc, channel->scan_index,
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 = 16;
return IIO_VAL_FRACTIONAL_LOG2;
default:
return -EINVAL;
}
}
static const struct iio_info ads8344_info = {
.read_raw = ads8344_read_raw,
};
static int ads8344_probe(struct spi_device *spi)
{
struct iio_dev *indio_dev;
struct ads8344 *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 = dev_name(&spi->dev);
indio_dev->dev.parent = &spi->dev;
indio_dev->dev.of_node = spi->dev.of_node;
indio_dev->info = &ads8344_info;
indio_dev->modes = INDIO_DIRECT_MODE;
indio_dev->channels = ads8344_channels;
indio_dev->num_channels = ARRAY_SIZE(ads8344_channels);
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;
}
return 0;
}
static int ads8344_remove(struct spi_device *spi)
{
struct iio_dev *indio_dev = spi_get_drvdata(spi);
struct ads8344 *adc = iio_priv(indio_dev);
iio_device_unregister(indio_dev);
regulator_disable(adc->reg);
return 0;
}
static const struct of_device_id ads8344_of_match[] = {
{ .compatible = "ti,ads8344", },
{}
};
MODULE_DEVICE_TABLE(of, ads8344_of_match);
static struct spi_driver ads8344_driver = {
.driver = {
.name = "ads8344",
.of_match_table = ads8344_of_match,
},
.probe = ads8344_probe,
.remove = ads8344_remove,
};
module_spi_driver(ads8344_driver);
MODULE_AUTHOR("Gregory CLEMENT <gregory.clement@bootlin.com>");
MODULE_DESCRIPTION("ADS8344 driver");
MODULE_LICENSE("GPL");