Message-ID: <562CD7EA.1030406@kernel.org>
Date:	Sun, 25 Oct 2015 13:23:54 +0000
From:	Jonathan Cameron <jic23@...nel.org>
To:	Paul Cercueil <paul.cercueil@...log.com>
Cc:	Hartmut Knaack <knaack.h@....de>,
	Lars-Peter Clausen <lars@...afoo.de>,
	Peter Meerwald <pmeerw@...erw.net>,
	Michael Hennerich <Michael.Hennerich@...log.com>,
	Antonio Fiol <antonio@...l.es>,
	Dmitry Eremin-Solenikov <dbaryshkov@...il.com>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org
Subject: Re: [PATCHv2 2/2] iio: dac: Add support for the AD5592R/AD5593R
 ADCs/DACs

On 13/10/15 10:38, Paul Cercueil wrote:
> This patch adds support for the AD5592R (spi) and AD5593R (i2c)
> ADC/DAC devices.
> 
> Signed-off-by: Paul Cercueil <paul.cercueil@...log.com>
A few minor questions inline...
> ---
>  drivers/iio/dac/Kconfig               |  27 ++++
>  drivers/iio/dac/Makefile              |   3 +
>  drivers/iio/dac/ad5592r-base.c        | 289 ++++++++++++++++++++++++++++++++++
>  drivers/iio/dac/ad5592r-base.h        |  56 +++++++
>  drivers/iio/dac/ad5592r.c             | 126 +++++++++++++++
>  drivers/iio/dac/ad5593r.c             | 121 ++++++++++++++
>  include/dt-bindings/iio/adi,ad5592r.h |  13 ++
>  7 files changed, 635 insertions(+)
>  create mode 100644 drivers/iio/dac/ad5592r-base.c
>  create mode 100644 drivers/iio/dac/ad5592r-base.h
>  create mode 100644 drivers/iio/dac/ad5592r.c
>  create mode 100644 drivers/iio/dac/ad5593r.c
>  create mode 100644 include/dt-bindings/iio/adi,ad5592r.h
> 
>  v2: Introduced changes suggested by upstream feedback
> 
> diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
> index e701e28..be7bb04 100644
> --- a/drivers/iio/dac/Kconfig
> +++ b/drivers/iio/dac/Kconfig
> @@ -72,6 +72,33 @@ config AD5449
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called ad5449.
>  
> +config AD5592R_BASE
> +	tristate
> +
> +config AD5592R
> +	tristate "Analog Devices AD5592R ADC/DAC driver"
> +	depends on SPI_MASTER
> +	depends on OF
> +	select AD5592R_BASE
> +	help
> +	  Say yes here to build support for Analog Devices AD5592R
> +	  Digital to Analog / Analog to Digital Converter.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called ad5592r.
> +
> +config AD5593R
> +	tristate "Analog Devices AD5593R ADC/DAC driver"
> +	depends on I2C
> +	depends on OF
> +	select AD5592R_BASE
> +	help
> +	  Say yes here to build support for Analog Devices AD5593R
> +	  Digital to Analog / Analog to Digital Converter.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called ad5593r.
> +
>  config AD5504
>  	tristate "Analog Devices AD5504/AD5501 DAC SPI driver"
>  	depends on SPI
> diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile
> index 63ae056..ae00b67 100644
> --- a/drivers/iio/dac/Makefile
> +++ b/drivers/iio/dac/Makefile
> @@ -11,6 +11,9 @@ obj-$(CONFIG_AD5064) += ad5064.o
>  obj-$(CONFIG_AD5504) += ad5504.o
>  obj-$(CONFIG_AD5446) += ad5446.o
>  obj-$(CONFIG_AD5449) += ad5449.o
> +obj-$(CONFIG_AD5592R_BASE) += ad5592r-base.o
> +obj-$(CONFIG_AD5592R) += ad5592r.o
> +obj-$(CONFIG_AD5593R) += ad5593r.o
>  obj-$(CONFIG_AD5755) += ad5755.o
>  obj-$(CONFIG_AD5764) += ad5764.o
>  obj-$(CONFIG_AD5791) += ad5791.o
> diff --git a/drivers/iio/dac/ad5592r-base.c b/drivers/iio/dac/ad5592r-base.c
> new file mode 100644
> index 0000000..c1132fd
> --- /dev/null
> +++ b/drivers/iio/dac/ad5592r-base.c
> @@ -0,0 +1,289 @@
> +/*
> + * AD5592R Digital <-> Analog converters driver
> + *
> + * Copyright 2014 Analog Devices Inc.
> + * Author: Paul Cercueil <paul.cercueil@...log.com>
> + *
> + * Licensed under the GPL-2.
> + */
> +
> +/*
> + * TODO:
> + *     - Add support for using channels as GPIOs
> + */
> +
> +#include "ad5592r-base.h"
> +
> +#include <dt-bindings/iio/adi,ad5592r.h>
> +
> +#include <linux/bitops.h>
> +#include <linux/delay.h>
> +#include <linux/iio/iio.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/of.h>
> +
> +static int ad5592r_set_channel_modes(struct ad5592r_state *st)
> +{
> +	const struct ad5592r_rw_ops *ops = st->ops;
> +	int ret;
> +	unsigned i;
> +	struct iio_dev *iio_dev = iio_priv_to_dev(st);
> +	u8 pulldown = 0, open_drain = 0, tristate = 0,
> +	   dac = 0, adc = 0, gpio_in = 0, gpio_out = 0;
> +	u16 read_back;
> +
> +	for (i = 0; i < st->num_channels; i++) {
> +		switch (st->channel_modes[i]) {
> +		case CH_MODE_DAC:
> +			dac |= BIT(i);
> +
> +		/* fall-through */
> +		case CH_MODE_ADC:
> +			adc |= BIT(i);
> +			break;
> +
> +		case CH_MODE_GPIO_OUT:
> +			gpio_out |= BIT(i);
> +
> +		/* fall-through */
> +		case CH_MODE_GPIO_IN:
> +			gpio_in |= BIT(i);
> +			break;
> +
> +		case CH_MODE_GPIO_OPEN_DRAIN:
> +			open_drain |= BIT(i);
> +			break;
> +
> +		case CH_MODE_GPIO_TRISTATE:
> +			tristate |= BIT(i);
> +			break;
> +
> +		default:
> +			pulldown |= BIT(i);
> +			break;
> +		}
> +	}
> +
> +	mutex_lock(&iio_dev->mlock);
> +
> +	/* Configure pins that we use */
> +	ret = ops->reg_write(st, AD5592R_REG_DAC_EN, dac);
> +	if (ret)
> +		goto err_unlock;
> +
> +	ret = ops->reg_write(st, AD5592R_REG_ADC_EN, adc);
> +	if (ret)
> +		goto err_unlock;
> +
> +	ret = ops->reg_write(st, AD5592R_REG_GPIO_OUT_EN, gpio_out);
> +	if (ret)
> +		goto err_unlock;
> +
> +	ret = ops->reg_write(st, AD5592R_REG_GPIO_IN_EN, gpio_in);
> +	if (ret)
> +		goto err_unlock;
> +
> +	ret = ops->reg_write(st, AD5592R_REG_OPEN_DRAIN, open_drain);
> +	if (ret)
> +		goto err_unlock;
> +
> +	ret = ops->reg_write(st, AD5592R_REG_TRISTATE, tristate);
> +	if (ret)
> +		goto err_unlock;
> +
> +	/* Pull down unused pins to GND */
> +	ret = ops->reg_write(st, AD5592R_REG_PULLDOWN, pulldown);
> +	if (ret)
> +		goto err_unlock;
> +
> +	/* Verify that we can read back at least one register */
> +	ret = ops->reg_read(st, AD5592R_REG_ADC_EN, &read_back);
> +	if (!ret && (read_back & 0xff) != adc)
> +		ret = -EIO;
> +
> +err_unlock:
> +	mutex_unlock(&iio_dev->mlock);
> +	return ret;
> +}
> +
> +static int ad5592r_write_raw(struct iio_dev *iio_dev,
> +	struct iio_chan_spec const *chan, int val, int val2, long mask)
> +{
> +	struct ad5592r_state *st = iio_priv(iio_dev);
> +	int ret;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		if (val >= (1 << chan->scan_type.realbits) || val < 0)
> +			return -EINVAL;
> +
> +		mutex_lock(&iio_dev->mlock);
How do we know this is a DAC channel?  I guess it might fault, but it would
certainly be good to make this more obvious.  Unlike the other way around
below, writing an ADC channel value makes no sense!
> +		ret = st->ops->dac_write(st, chan->address, val);
> +		mutex_unlock(&iio_dev->mlock);
> +		return ret;
> +
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int ad5592r_read_raw(struct iio_dev *iio_dev,
> +			   struct iio_chan_spec const *chan,
> +			   int *val, int *val2, long m)
> +{
> +	struct ad5592r_state *st = iio_priv(iio_dev);
> +	u16 read_val;
> +	int ret;
> +
> +	switch (m) {
> +	case IIO_CHAN_INFO_RAW:
> +		mutex_lock(&iio_dev->mlock);
Is there anything to say this is an ADC channel rather than a DAC one?
Might not be a problem reading back from a dac, but then the comments
and naming need adjusting.

> +		ret = st->ops->adc_read(st, chan->channel, &read_val);
> +		mutex_unlock(&iio_dev->mlock);
> +		if (ret)
> +			return ret;
> +
> +		if ((read_val >> 12 & 0x7) != chan->channel) {
> +			dev_err(st->dev, "Error while reading channel %u\n",
> +					chan->channel);
> +			return -EIO;
> +		}
> +
> +		read_val &= GENMASK(11, 0);
> +
> +		dev_dbg(st->dev, "ADC read: 0x%04hX\n", read_val);
> +		*val = (int) read_val;
> +		return IIO_VAL_INT;
> +
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static void ad5592r_reset(struct ad5592r_state *st)
> +{
> +	struct iio_dev *iio_dev = iio_priv_to_dev(st);
> +
> +	mutex_lock(&iio_dev->mlock);
> +	st->ops->reg_write(st, AD5592R_REG_RESET, 0xdac);
> +	udelay(250);
> +	mutex_unlock(&iio_dev->mlock);
> +}
> +
> +static const struct iio_info ad5592r_info = {
> +	.read_raw = ad5592r_read_raw,
> +	.write_raw = ad5592r_write_raw,
> +	.driver_module = THIS_MODULE,
> +};
> +
> +static void ad5592r_setup_channel(struct iio_dev *iio_dev,
> +		struct iio_chan_spec *chan, bool output, unsigned id)
> +{
> +	chan->type = IIO_VOLTAGE;
> +	chan->indexed = 1;
> +	chan->output = output;
> +	chan->channel = id;
> +	chan->info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
> +	chan->address = id;
There is little purpose in providing an address value if it always
matches the channel value - just use that directly.

> +	chan->scan_type.sign = 'u';
> +	chan->scan_type.realbits = 12;
> +	chan->scan_type.storagebits = 16;
> +}
> +
> +static int ad5592r_alloc_channels(struct ad5592r_state *st)
> +{
> +	unsigned i, curr_channel = 0,
> +		 num_channels = st->num_channels;
> +	struct iio_dev *iio_dev = iio_priv_to_dev(st);
> +	struct iio_chan_spec *channels;
> +	int ret;
> +
> +	ret = of_property_read_u8_array(st->dev->of_node, "channel-modes",
> +			st->channel_modes, num_channels);
> +	if (ret)
> +		return ret;
> +
> +	channels = devm_kzalloc(st->dev,
> +			2 * num_channels * sizeof(*channels), GFP_KERNEL);
> +	if (!channels)
> +		return -ENOMEM;
> +
> +	for (i = 0; i < num_channels; i++) {
> +		switch (st->channel_modes[i]) {
> +		case CH_MODE_DAC:
> +			ad5592r_setup_channel(iio_dev, &channels[curr_channel],
> +					true, curr_channel);
> +			curr_channel++;
> +			break;
> +
> +		case CH_MODE_ADC:
> +			ad5592r_setup_channel(iio_dev, &channels[curr_channel],
> +					false, curr_channel);
> +			curr_channel++;
> +
> +		/* fall-through */
> +		default:
> +			continue;
> +		}
> +	}
> +
> +	iio_dev->num_channels = curr_channel;
> +	iio_dev->channels = channels;
> +
> +	return 0;
> +}
> +
> +int ad5592r_probe(struct device *dev, const char *name,
> +		const struct ad5592r_rw_ops *ops)
> +{
> +	struct iio_dev *iio_dev;
> +	struct ad5592r_state *st;
> +	int ret;
> +
> +	iio_dev = devm_iio_device_alloc(dev, sizeof(*st));
> +	if (!iio_dev)
> +		return -ENOMEM;
> +
> +	st = iio_priv(iio_dev);
> +	st->dev = dev;
> +	st->ops = ops;
> +	st->num_channels = 8;
> +	dev_set_drvdata(dev, iio_dev);
> +
> +	iio_dev->dev.parent = dev;
> +	iio_dev->name = name;
> +	iio_dev->info = &ad5592r_info;
> +	iio_dev->modes = INDIO_DIRECT_MODE;
> +
> +	ad5592r_reset(st);
> +
> +	ret = ad5592r_alloc_channels(st);
> +	if (ret)
> +		return ret;
> +
> +	ret = ad5592r_set_channel_modes(st);
> +	if (ret)
> +		return ret;
> +
> +	return devm_iio_device_register(dev, iio_dev);
> +}
> +EXPORT_SYMBOL_GPL(ad5592r_probe);
> +
> +int ad5592r_remove(struct device *dev)
> +{
> +	struct iio_dev *iio_dev = dev_get_drvdata(dev);
> +	struct ad5592r_state *st = iio_priv(iio_dev);
> +	unsigned int i;
> +
> +	/* Reset all channels */
> +	for (i = 0; i < ARRAY_SIZE(st->channel_modes); i++)
> +		st->channel_modes[i] = CH_MODE_UNUSED;
> +
> +	return ad5592r_set_channel_modes(st);
> +}
> +EXPORT_SYMBOL_GPL(ad5592r_remove);
> +
> +MODULE_AUTHOR("Paul Cercueil <paul.cercueil@...log.com>");
> +MODULE_DESCRIPTION("Analog Devices AD5592R multi-channel converters");
> +MODULE_LICENSE("GPL v2");
> diff --git a/drivers/iio/dac/ad5592r-base.h b/drivers/iio/dac/ad5592r-base.h
> new file mode 100644
> index 0000000..d722e0c
> --- /dev/null
> +++ b/drivers/iio/dac/ad5592r-base.h
> @@ -0,0 +1,56 @@
> +/*
> + * AD5592R / AD5593R Digital <-> Analog converters driver
> + *
> + * Copyright 2015 Analog Devices Inc.
> + * Author: Paul Cercueil <paul.cercueil@...log.com>
> + *
> + * Licensed under the GPL-2.
> + */
> +
> +#ifndef __DRIVERS_IIO_DAC_AD5592R_BASE_H__
> +#define __DRIVERS_IIO_DAC_AD5592R_BASE_H__
> +
> +#include <linux/types.h>
> +#include <linux/cache.h>
> +
> +struct device;
> +struct ad5592r_state;
> +
> +enum ad5592r_registers {
> +	AD5592R_REG_NOOP		= 0x0,
> +	AD5592R_REG_DAC_READBACK	= 0x1,
> +	AD5592R_REG_ADC_SEQ		= 0x2,
> +	AD5592R_REG_CTRL		= 0x3,
> +	AD5592R_REG_ADC_EN		= 0x4,
> +	AD5592R_REG_DAC_EN		= 0x5,
> +	AD5592R_REG_PULLDOWN		= 0x6,
> +	AD5592R_REG_LDAC		= 0x7,
> +	AD5592R_REG_GPIO_OUT_EN		= 0x8,
> +	AD5592R_REG_GPIO_SET		= 0x9,
> +	AD5592R_REG_GPIO_IN_EN		= 0xA,
> +	AD5592R_REG_PD			= 0xB,
> +	AD5592R_REG_OPEN_DRAIN		= 0xC,
> +	AD5592R_REG_TRISTATE		= 0xD,
> +	AD5592R_REG_RESET		= 0xF,
> +};
> +
> +struct ad5592r_rw_ops {
> +	int (*dac_write)(struct ad5592r_state *st, unsigned chan, u16 value);
> +	int (*adc_read)(struct ad5592r_state *st, unsigned chan, u16 *value);
> +	int (*reg_write)(struct ad5592r_state *st, u8 reg, u16 value);
> +	int (*reg_read)(struct ad5592r_state *st, u8 reg, u16 *value);
> +};
> +
> +struct ad5592r_state {
> +	struct device *dev;
> +	unsigned int num_channels;
> +	const struct ad5592r_rw_ops *ops;
> +	u8 channel_modes[8];
> +	__be16 spi_msg ____cacheline_aligned;
> +};
> +
> +int ad5592r_probe(struct device *dev, const char *name,
> +		const struct ad5592r_rw_ops *ops);
> +int ad5592r_remove(struct device *dev);
> +
> +#endif /* __DRIVERS_IIO_DAC_AD5592R_BASE_H__ */
> diff --git a/drivers/iio/dac/ad5592r.c b/drivers/iio/dac/ad5592r.c
> new file mode 100644
> index 0000000..0572a36
> --- /dev/null
> +++ b/drivers/iio/dac/ad5592r.c
> @@ -0,0 +1,126 @@
> +/*
> + * AD5592R Digital <-> Analog converters driver
> + *
> + * Copyright 2015 Analog Devices Inc.
> + * Author: Paul Cercueil <paul.cercueil@...log.com>
> + *
> + * Licensed under the GPL-2.
> + */
> +
> +#include "ad5592r-base.h"
> +
> +#include <linux/bitops.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/spi/spi.h>
> +
> +static int ad5592r_dac_write(struct ad5592r_state *st, unsigned chan, u16 value)
> +{
> +	struct spi_device *spi = container_of(st->dev, struct spi_device, dev);
> +
> +	st->spi_msg = cpu_to_be16(BIT(15) | (chan << 12) | value);
> +
> +	return spi_write(spi, &st->spi_msg, sizeof(st->spi_msg));
> +}
> +
> +static int ad5592r_adc_read(struct ad5592r_state *st, unsigned chan, u16 *value)
> +{
> +	struct spi_device *spi = container_of(st->dev, struct spi_device, dev);
> +	int ret;
> +
> +	st->spi_msg = cpu_to_be16((AD5592R_REG_ADC_SEQ << 11) | BIT(chan));
> +
> +	ret = spi_write(spi, &st->spi_msg, sizeof(st->spi_msg));
> +	if (ret)
> +		return ret;
> +
> +	/* Invalid data */
> +	ret = spi_read(spi, &st->spi_msg, sizeof(st->spi_msg));
> +	if (ret)
> +		return ret;
> +
> +	ret = spi_read(spi, &st->spi_msg, sizeof(st->spi_msg));
> +	if (ret)
> +		return ret;
> +
> +	*value = be16_to_cpu(st->spi_msg);
> +
> +	return 0;
> +}
> +
> +static int ad5592r_reg_write(struct ad5592r_state *st, u8 reg, u16 value)
> +{
> +	struct spi_device *spi = container_of(st->dev, struct spi_device, dev);
> +
> +	st->spi_msg = cpu_to_be16((reg << 11) | value);
> +
> +	return spi_write(spi, &st->spi_msg, sizeof(st->spi_msg));
> +}
> +
> +static int ad5592r_reg_read(struct ad5592r_state *st, u8 reg, u16 *value)
> +{
> +	struct spi_device *spi = container_of(st->dev, struct spi_device, dev);
> +	int ret;
> +
> +	st->spi_msg = cpu_to_be16(
> +			(AD5592R_REG_LDAC << 11) | BIT(6) | (reg << 2));
> +
> +	ret = spi_write(spi, &st->spi_msg, sizeof(st->spi_msg));
> +	if (ret)
> +		return ret;
> +
> +	ret = spi_read(spi, &st->spi_msg, sizeof(st->spi_msg));
> +	if (ret)
> +		return ret;
> +
> +	if (value)
> +		*value = be16_to_cpu(st->spi_msg);
> +
> +	return 0;
> +}
> +
> +static const struct ad5592r_rw_ops ad5592r_rw_ops = {
> +	.dac_write = ad5592r_dac_write,
> +	.adc_read = ad5592r_adc_read,
> +	.reg_write = ad5592r_reg_write,
> +	.reg_read = ad5592r_reg_read,
> +};
> +
> +static int ad5592r_spi_probe(struct spi_device *spi)
> +{
> +	const struct spi_device_id *id = spi_get_device_id(spi);
> +
> +	return ad5592r_probe(&spi->dev, id->name, &ad5592r_rw_ops);
> +}
> +
> +static int ad5592r_spi_remove(struct spi_device *spi)
> +{
> +	return ad5592r_remove(&spi->dev);
> +}
> +
> +static const struct spi_device_id ad5592r_spi_ids[] = {
> +	{ .name = "ad5592r", },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(spi, ad5592r_spi_ids);
> +
> +static const struct of_device_id ad5592r_of_match[] = {
> +	{ .compatible = "adi,ad5592r", },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, ad5592r_of_match);
> +
> +static struct spi_driver ad5592r_spi_driver = {
> +	.driver = {
> +		.name = "ad5592r",
> +		.of_match_table = of_match_ptr(ad5592r_of_match),
> +	},
> +	.probe = ad5592r_spi_probe,
> +	.remove = ad5592r_spi_remove,
> +	.id_table = ad5592r_spi_ids,
> +};
> +module_spi_driver(ad5592r_spi_driver);
> +
> +MODULE_AUTHOR("Paul Cercueil <paul.cercueil@...log.com>");
> +MODULE_DESCRIPTION("Analog Devices AD5592R multi-channel converters");
> +MODULE_LICENSE("GPL v2");
> diff --git a/drivers/iio/dac/ad5593r.c b/drivers/iio/dac/ad5593r.c
> new file mode 100644
> index 0000000..6825834
> --- /dev/null
> +++ b/drivers/iio/dac/ad5593r.c
> @@ -0,0 +1,121 @@
> +/*
> + * AD5593R Digital <-> Analog converters driver
> + *
> + * Copyright 2015 Analog Devices Inc.
> + * Author: Paul Cercueil <paul.cercueil@...log.com>
> + *
> + * Licensed under the GPL-2.
> + */
> +
> +#include "ad5592r-base.h"
> +
> +#include <linux/bitops.h>
> +#include <linux/i2c.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +
> +#define AD5593R_MODE_CONF		(0 << 4)
> +#define AD5593R_MODE_DAC_WRITE		(1 << 4)
> +#define AD5593R_MODE_ADC_READBACK	(4 << 4)
> +#define AD5593R_MODE_DAC_READBACK	(5 << 4)
> +#define AD5593R_MODE_GPIO_READBACK	(6 << 4)
> +#define AD5593R_MODE_REG_READBACK	(7 << 4)
> +
> +static int ad5593r_dac_write(struct ad5592r_state *st, unsigned chan, u16 value)
> +{
> +	struct i2c_client *i2c = to_i2c_client(st->dev);
> +
> +	return i2c_smbus_write_word_swapped(i2c,
> +			AD5593R_MODE_DAC_WRITE | chan, value);
> +}
> +
> +static int ad5593r_adc_read(struct ad5592r_state *st, unsigned chan, u16 *value)
> +{
> +	struct i2c_client *i2c = to_i2c_client(st->dev);
> +	s32 val;
> +
> +	val = i2c_smbus_write_word_swapped(i2c,
> +			AD5593R_MODE_CONF | AD5592R_REG_ADC_SEQ, BIT(chan));
> +	if (val < 0)
> +		return (int) val;
> +
> +	/* Invalid data */
> +	val = i2c_smbus_read_word_swapped(i2c, AD5593R_MODE_ADC_READBACK);
> +	if (val < 0)
> +		return (int) val;
> +
> +	val = i2c_smbus_read_word_swapped(i2c, AD5593R_MODE_ADC_READBACK);
> +	if (val < 0)
> +		return (int) val;
> +
> +	*value = (u16) val;
> +
> +	return 0;
> +}
> +
> +static int ad5593r_reg_write(struct ad5592r_state *st, u8 reg, u16 value)
> +{
> +	struct i2c_client *i2c = to_i2c_client(st->dev);
> +
> +	return i2c_smbus_write_word_swapped(i2c,
> +			AD5593R_MODE_CONF | reg, value);
> +}
> +
> +static int ad5593r_reg_read(struct ad5592r_state *st, u8 reg, u16 *value)
> +{
> +	struct i2c_client *i2c = to_i2c_client(st->dev);
> +	s32 val;
> +
> +	val = i2c_smbus_read_word_swapped(i2c, AD5593R_MODE_REG_READBACK | reg);
> +	if (val < 0)
> +		return (int) val;
> +
> +	*value = (u16) val;
> +
> +	return 0;
> +}
> +
> +static const struct ad5592r_rw_ops ad5593r_rw_ops = {
> +	.dac_write = ad5593r_dac_write,
> +	.adc_read = ad5593r_adc_read,
> +	.reg_write = ad5593r_reg_write,
> +	.reg_read = ad5593r_reg_read,
> +};
> +
> +static int ad5593r_i2c_probe(struct i2c_client *i2c,
> +		const struct i2c_device_id *id)
> +{
> +	return ad5592r_probe(&i2c->dev, id->name, &ad5593r_rw_ops);
> +}
> +
> +static int ad5593r_i2c_remove(struct i2c_client *i2c)
> +{
> +	return ad5592r_remove(&i2c->dev);
> +}
> +
> +static const struct i2c_device_id ad5593r_i2c_ids[] = {
> +	{ .name = "ad5593r", },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(i2c, ad5593r_i2c_ids);
> +
> +static const struct of_device_id ad5593r_of_match[] = {
> +	{ .compatible = "adi,ad5593r", },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, ad5593r_of_match);
> +
> +static struct i2c_driver ad5593r_driver = {
> +	.driver = {
> +		.name = "ad5593r",
> +		.of_match_table = of_match_ptr(ad5593r_of_match),
> +	},
> +	.probe = ad5593r_i2c_probe,
> +	.remove = ad5593r_i2c_remove,
> +	.id_table = ad5593r_i2c_ids,
> +};
> +module_i2c_driver(ad5593r_driver);
> +
> +MODULE_AUTHOR("Paul Cercueil <paul.cercueil@...log.com>");
> +MODULE_DESCRIPTION("Analog Devices AD5592R multi-channel converters");
> +MODULE_LICENSE("GPL v2");
> diff --git a/include/dt-bindings/iio/adi,ad5592r.h b/include/dt-bindings/iio/adi,ad5592r.h
> new file mode 100644
> index 0000000..fcb6293
> --- /dev/null
> +++ b/include/dt-bindings/iio/adi,ad5592r.h
> @@ -0,0 +1,13 @@
> +
> +#ifndef _DT_BINDINGS_ADI_AD5592R_H
> +#define _DT_BINDINGS_ADI_AD5592R_H
> +
> +#define CH_MODE_UNUSED		0
> +#define CH_MODE_DAC		1
> +#define CH_MODE_ADC		2
> +#define CH_MODE_GPIO_OUT	3
> +#define CH_MODE_GPIO_IN		4
> +#define CH_MODE_GPIO_OPEN_DRAIN	5
> +#define CH_MODE_GPIO_TRISTATE	6
> +
> +#endif /* _DT_BINDINGS_ADI_AD5592R_H */
> 

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