Commit 8dd2d7c0 authored by Gregory CLEMENT's avatar Gregory CLEMENT Committed by Jonathan Cameron
Browse files

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: default avatarGregory CLEMENT <gregory.clement@bootlin.com>
Signed-off-by: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
parent 65c7a3d2

drivers/iio/adc/Kconfig

+10 −0
Original line number Diff line number Diff line
@@ -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

drivers/iio/adc/Makefile

+1 −0
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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

drivers/iio/adc/ti-ads8344.c

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+204 −0
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// 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");

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