[v3] iio: dac: Add support for the AD5592R/AD5593R ADCs/DACs

From: Paul Cercueil <paul.cercueil@analog.com>

This patch adds support for the AD5592R (spi) and AD5593R (i2c)
ADC/DAC devices.

Signed-off-by: Paul Cercueil <paul.cercueil@analog.com>
Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>

Changes since v1:
	* Fix mutex usage
	* Remove unnecessary NULL pointer guards
	* Add comment explaining the invalid data read
	* AD5593R Remove surplus adc readback

Changes since v2:
	* Use child nodes to describe channels
	* Fix probe return and driver remove path
	* Move locking closer to where its used
	* Remove WARN_ON but return error
	* Remove OPEN DRAIN configuration option

---
---
 .../devicetree/bindings/iio/dac/ad5592r.txt        | 143 +++++
 drivers/iio/dac/Kconfig                            |  27 +
 drivers/iio/dac/Makefile                           |   3 +
 drivers/iio/dac/ad5592r-base.c                     | 702 +++++++++++++++++++++
 drivers/iio/dac/ad5592r-base.h                     |  78 +++
 drivers/iio/dac/ad5592r.c                          | 164 +++++
 drivers/iio/dac/ad5593r.c                          | 131 ++++
 include/dt-bindings/iio/adi,ad5592r.h              |  16 +
 8 files changed, 1264 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/dac/ad5592r.txt
 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

On Thu, Mar 03, 2016 at 01:58:03PM +0100, michael.hennerich@analog.com wrote:
> From: Paul Cercueil <paul.cercueil@analog.com>
> 
> This patch adds support for the AD5592R (spi) and AD5593R (i2c)
> ADC/DAC devices.
> 
> Signed-off-by: Paul Cercueil <paul.cercueil@analog.com>
> Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>

[...]

> +AD5592R Example:
> +
> +	#include <dt-bindings/iio/adi,ad5592r.h>
> +
> +	vref: regulator-vref {
> +		compatible = "regulator-fixed";
> +		regulator-name = "vref-ad559x";
> +		regulator-min-microvolt = <3300000>;
> +		regulator-max-microvolt = <3300000>;
> +		regulator-always-on;
> +	};
> +
> +	ad5592r@0 {
> +		#size-cells = <0>;
> +		#address-cells = <1>;
> +		compatible = "adi,ad5592r";
> +		reg = <0>;
> +		spi-max-frequency = <1000000>;
> +		spi-cpol;
> +
> +		vref-supply = <&vref>; /* optional */
> +		reset-gpios = <&gpio0 86 0>;  /* optional */
> +
> +		channel@0 {
> +			reg = <0>;
> +			mode = <CH_MODE_DAC>;

You are missing the vendor prefixes thoughout.
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On 03/03/16 12:58, michael.hennerich@analog.com wrote:
> From: Paul Cercueil <paul.cercueil@analog.com>
> 
> This patch adds support for the AD5592R (spi) and AD5593R (i2c)
> ADC/DAC devices.
> 
> Signed-off-by: Paul Cercueil <paul.cercueil@analog.com>
> Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
> 
> Changes since v1:
> 	* Fix mutex usage
> 	* Remove unnecessary NULL pointer guards
> 	* Add comment explaining the invalid data read
> 	* AD5593R Remove surplus adc readback
> 
> Changes since v2:
> 	* Use child nodes to describe channels
> 	* Fix probe return and driver remove path
> 	* Move locking closer to where its used
> 	* Remove WARN_ON but return error
> 	* Remove OPEN DRAIN configuration option
Why? I don't particularly mind as of course you aren't obliged to support
every option in a driver, but I'm curious ;)

Otherwise, one minor rearrangement in the remove function would tidy up
the ordering a little + obviously Rob's binding example comment to be cleaned
up.

I'd also like a gpio chip ack.   Plenty of time now as the merge window
for IIO is pretty much closed for this cycle now anyway (probably!)

Jonathan
> 
> ---
> ---
>  .../devicetree/bindings/iio/dac/ad5592r.txt        | 143 +++++
>  drivers/iio/dac/Kconfig                            |  27 +
>  drivers/iio/dac/Makefile                           |   3 +
>  drivers/iio/dac/ad5592r-base.c                     | 702 +++++++++++++++++++++
>  drivers/iio/dac/ad5592r-base.h                     |  78 +++
>  drivers/iio/dac/ad5592r.c                          | 164 +++++
>  drivers/iio/dac/ad5593r.c                          | 131 ++++
>  include/dt-bindings/iio/adi,ad5592r.h              |  16 +
>  8 files changed, 1264 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iio/dac/ad5592r.txt
>  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
> 
> diff --git a/Documentation/devicetree/bindings/iio/dac/ad5592r.txt b/Documentation/devicetree/bindings/iio/dac/ad5592r.txt
> new file mode 100644
> index 0000000..8e2530b
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/dac/ad5592r.txt
> @@ -0,0 +1,143 @@
> +Analog Devices AD5592R/AD5593R DAC/ADC device driver
> +
> +Required properties for the AD5592R:
> +	- compatible: Must be "adi,ad5592r"
> +	- reg: SPI chip select number for the device
> +	- spi-max-frequency: Max SPI frequency to use (< 30000000)
> +	- spi-cpol: The AD5592R requires inverse clock polarity (CPOL) mode
> +
> +Required properties for the AD5593R:
> +	- compatible: Must be "adi,ad5593r"
> +	- reg: I2C address of the device
> +
> +Required properties for all supported chips:
> +	- #address-cells: Should be 1.
> +	- #size-cells: Should be 0.
> +	- channel nodes:
> +	  Each child node represents one channel and has the following
> +	  Required properties:
> +		* reg: Pin on which this channel is connected to.
> +		* adi,mode: Mode or function of this channel.
> +			    Macros specifying the valid values
> +			    can be found in <dt-bindings/iio/adi,ad5592r.h>.
> +
> +			    The following values are currently supported:
> +				* CH_MODE_UNUSED (the pin is unused)
> +				* CH_MODE_ADC (the pin is ADC input)
> +				* CH_MODE_DAC (the pin is DAC output)
> +				* CH_MODE_DAC_AND_ADC (the pin is DAC output
> +					but can be monitored by an ADC)
> +				* CH_MODE_GPIO (the pin is registered
> +					with GPIOLIB)
Still feels like this should be me more generic than a adi specific binding.
The nearest I can come up with elsewhere in the kernel is pinctrl's
function binding.  I think that would map as something like:

channel@3 {
	function = "adc1";
	pins = "pin1"
};

Doesn't really work though so perhaps we need to go with this as it is with a
view to revisiting the question sometime in the future perhaps.
> +	 Optional properties:
> +		* adi,off-state: State of this channel when unused or the
> +				 device gets removed. Macros specifying the
> +				 valid values can be found in
> +				 <dt-bindings/iio/adi,ad5592r.h>.
> +
> +				* CH_OFFSTATE_PULLDOWN (the pin is pulled down)
> +				* CH_OFFSTATE_OUT_LOW  (the pin is output low)
> +				* CH_OFFSTATE_OUT_HIGH (the pin is output high)
> +				* CH_OFFSTATE_OUT_TRISTATE (the pin is
> +					tristated output)
> +
> +
> +Optional properties:
> +	- vref-supply: Phandle to the external reference voltage supply. This should
> +	  only be set if there is an external reference voltage connected to the VREF
> +	  pin. If the property is not set the internal 2.5V reference is used.
> +	- reset-gpios : GPIO spec for the RESET pin. If specified, it will be
> +	  asserted during driver probe.
> +
> +AD5592R Example:
> +
> +	#include <dt-bindings/iio/adi,ad5592r.h>
> +
> +	vref: regulator-vref {
> +		compatible = "regulator-fixed";
> +		regulator-name = "vref-ad559x";
> +		regulator-min-microvolt = <3300000>;
> +		regulator-max-microvolt = <3300000>;
> +		regulator-always-on;
> +	};
> +
> +	ad5592r@0 {
> +		#size-cells = <0>;
> +		#address-cells = <1>;
> +		compatible = "adi,ad5592r";
> +		reg = <0>;
> +		spi-max-frequency = <1000000>;
> +		spi-cpol;
> +
> +		vref-supply = <&vref>; /* optional */
> +		reset-gpios = <&gpio0 86 0>;  /* optional */
> +
> +		channel@0 {
> +			reg = <0>;
> +			mode = <CH_MODE_DAC>;
> +		};
> +		channel@1 {
> +			reg = <1>;
> +			mode = <CH_MODE_ADC>;
> +		};
> +		channel@2 {
> +			reg = <2>;
> +			mode = <CH_MODE_DAC_AND_ADC>;
> +		};
> +		channel@3 {
> +			reg = <3>;
> +			mode = <CH_MODE_DAC_AND_ADC>;
> +			offstate = <CH_OFFSTATE_PULLDOWN>;
> +		};
> +		channel@4 {
> +			reg = <4>;
> +			mode = <CH_MODE_UNUSED>;
> +			offstate = <CH_OFFSTATE_PULLDOWN>;
> +		};
> +		channel@5 {
> +			reg = <5>;
> +			mode = <CH_MODE_GPIO>;
> +			offstate = <CH_OFFSTATE_PULLDOWN>;
> +		};
> +		channel@6 {
> +			reg = <6>;
> +			mode = <CH_MODE_GPIO>;
> +			offstate = <CH_OFFSTATE_PULLDOWN>;
> +		};
> +		channel@7 {
> +			reg = <7>;
> +			mode = <CH_MODE_GPIO>;
> +			offstate = <CH_OFFSTATE_PULLDOWN>;
> +		};
> +	};
> +
> +AD5593R Example:
> +
> +	#include <dt-bindings/iio/adi,ad5592r.h>
> +
> +	ad5593r@10 {
> +		#size-cells = <0>;
> +		#address-cells = <1>;
> +		compatible = "adi,ad5593r";
> +		reg = <0x10>;
> +		channel@0 {
> +			reg = <0>;
> +			mode = <CH_MODE_DAC>;
> +			offstate = <CH_OFFSTATE_PULLDOWN>;
> +		};
> +		channel@1 {
> +			reg = <1>;
> +			mode = <CH_MODE_ADC>;
> +			offstate = <CH_OFFSTATE_PULLDOWN>;
> +		};
> +		channel@2 {
> +			reg = <2>;
> +			mode = <CH_MODE_DAC_AND_ADC>;
> +			offstate = <CH_OFFSTATE_PULLDOWN>;
> +		};
> +		channel@6 {
> +			reg = <6>;
> +			mode = <CH_MODE_GPIO>;
> +			offstate = <CH_OFFSTATE_PULLDOWN>;
> +		};
> +	};
> diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
> index a995139..8c78ece 100644
> --- a/drivers/iio/dac/Kconfig
> +++ b/drivers/iio/dac/Kconfig
> @@ -74,6 +74,33 @@ 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 67b4842..de28cd2 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-$(CONFIG_AD5761) += ad5761.o
>  obj-$(CONFIG_AD5764) += ad5764.o
> diff --git a/drivers/iio/dac/ad5592r-base.c b/drivers/iio/dac/ad5592r-base.c
> new file mode 100644
> index 0000000..8fb3b23
> --- /dev/null
> +++ b/drivers/iio/dac/ad5592r-base.c
> @@ -0,0 +1,702 @@
> +/*
> + * AD5592R Digital <-> Analog converters driver
> + *
> + * Copyright 2014-2016 Analog Devices Inc.
> + * Author: Paul Cercueil <paul.cercueil@analog.com>
> + *
> + * Licensed under the GPL-2.
> + */
> +
> +#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>
> +#include <linux/regulator/consumer.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/gpio/driver.h>
> +#include <linux/gpio.h>
> +#include <linux/property.h>
> +
> +#include <dt-bindings/iio/adi,ad5592r.h>
> +
> +#include "ad5592r-base.h"
> +
> +#ifdef CONFIG_GPIOLIB
> +
> +static int ad5592r_gpio_get(struct gpio_chip *chip, unsigned offset)
> +{
> +	struct ad5592r_state *st = gpiochip_get_data(chip);
> +	int ret = 0;
> +	u8 val;
> +
> +	mutex_lock(&st->gpio_lock);
> +
> +	if (st->gpio_out & BIT(offset))
> +		val = st->gpio_val;
> +	else
> +		ret = st->ops->gpio_read(st, &val);
> +
> +	mutex_unlock(&st->gpio_lock);
> +
> +	if (ret < 0)
> +		return ret;
> +
> +	return !!(val & BIT(offset));
> +}
> +
> +static void ad5592r_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
> +{
> +	struct ad5592r_state *st = gpiochip_get_data(chip);
> +
> +	mutex_lock(&st->gpio_lock);
> +
> +	if (value)
> +		st->gpio_val |= BIT(offset);
> +	else
> +		st->gpio_val &= ~BIT(offset);
> +
> +	st->ops->reg_write(st, AD5592R_REG_GPIO_SET, st->gpio_val);
> +
> +	mutex_unlock(&st->gpio_lock);
> +}
> +
> +static int ad5592r_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
> +{
> +	struct ad5592r_state *st = gpiochip_get_data(chip);
> +	int ret;
> +
> +	mutex_lock(&st->gpio_lock);
> +
> +	st->gpio_out &= ~BIT(offset);
> +	st->gpio_in |= BIT(offset);
> +
> +	ret = st->ops->reg_write(st, AD5592R_REG_GPIO_OUT_EN, st->gpio_out);
> +	if (ret < 0)
> +		goto err_unlock;
> +
> +	ret = st->ops->reg_write(st, AD5592R_REG_GPIO_IN_EN, st->gpio_in);
> +
> +err_unlock:
> +	mutex_unlock(&st->gpio_lock);
> +
> +	return ret;
> +}
> +
> +static int ad5592r_gpio_direction_output(struct gpio_chip *chip,
> +					 unsigned offset, int value)
> +{
> +	struct ad5592r_state *st = gpiochip_get_data(chip);
> +	int ret;
> +
> +	mutex_lock(&st->gpio_lock);
> +
> +	if (value)
> +		st->gpio_val |= BIT(offset);
> +	else
> +		st->gpio_val &= ~BIT(offset);
> +
> +	st->gpio_in &= ~BIT(offset);
> +	st->gpio_out |= BIT(offset);
> +
> +	ret = st->ops->reg_write(st, AD5592R_REG_GPIO_SET, st->gpio_val);
> +	if (ret < 0)
> +		goto err_unlock;
> +
> +	ret = st->ops->reg_write(st, AD5592R_REG_GPIO_OUT_EN, st->gpio_out);
> +	if (ret < 0)
> +		goto err_unlock;
> +
> +	ret = st->ops->reg_write(st, AD5592R_REG_GPIO_IN_EN, st->gpio_in);
> +
> +err_unlock:
> +	mutex_unlock(&st->gpio_lock);
> +
> +	return ret;
> +}
> +
> +static int ad5592r_gpio_request(struct gpio_chip *chip, unsigned offset)
> +{
> +	struct ad5592r_state *st = gpiochip_get_data(chip);
> +
> +	if (!(st->gpio_map & BIT(offset))) {
> +		dev_err(st->dev, "GPIO %d is reserved by alternate function\n",
> +			offset);
> +		return -ENODEV;
> +	}
> +
> +	if (offset >= chip->ngpio)
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +
> +static int ad5592r_gpio_init(struct ad5592r_state *st)
> +{
> +	if (!st->gpio_map)
> +		return 0;
> +
> +	st->gpiochip.label = dev_name(st->dev);
> +	st->gpiochip.base = -1;
> +	st->gpiochip.ngpio = 8;
> +	st->gpiochip.parent = st->dev;
> +	st->gpiochip.can_sleep = true;
> +	st->gpiochip.direction_input = ad5592r_gpio_direction_input;
> +	st->gpiochip.direction_output = ad5592r_gpio_direction_output;
> +	st->gpiochip.get = ad5592r_gpio_get;
> +	st->gpiochip.set = ad5592r_gpio_set;
> +	st->gpiochip.request = ad5592r_gpio_request;
> +	st->gpiochip.owner = THIS_MODULE;
> +
> +	mutex_init(&st->gpio_lock);
> +
> +	return gpiochip_add_data(&st->gpiochip, st);
> +}
> +
> +static void ad5592r_gpio_cleanup(struct ad5592r_state *st)
> +{
> +	if (st->gpio_map)
> +		gpiochip_remove(&st->gpiochip);
> +}
> +#else
> +static int ad5592r_gpio_init(struct ad5592r_state *st) { return 0 };
> +static void ad5592r_gpio_cleanup(struct ad5592r_state *st) { };
> +#endif /* CONFIG_GPIOLIB */
> +
> +static int ad5592r_reset(struct ad5592r_state *st)
> +{
> +	struct gpio_desc *gpio;
> +	struct iio_dev *iio_dev = iio_priv_to_dev(st);
> +
> +	gpio = devm_gpiod_get_optional(st->dev, "reset", GPIOD_OUT_LOW);
> +	if (IS_ERR(gpio))
> +		return PTR_ERR(gpio);
> +
> +	if (gpio) {
> +		udelay(1);
> +		gpiod_set_value(gpio, 1);
> +	} else {
> +		mutex_lock(&iio_dev->mlock);
> +		st->ops->reg_write(st, AD5592R_REG_RESET, 0xdac);
> +		mutex_unlock(&iio_dev->mlock);
> +	}
> +
> +	udelay(250);
> +
> +	return 0;
> +}
> +
> +static int ad5592r_get_vref(struct ad5592r_state *st)
> +{
> +	int ret;
> +
> +	if (st->reg) {
> +		ret = regulator_get_voltage(st->reg);
> +		if (ret < 0)
> +			return ret;
> +
> +		return ret / 1000;
> +	} else {
> +		return 2500;
> +	}
> +}
> +
> +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, tristate = 0, dac = 0, adc = 0;
> +	u16 read_back;
> +
> +	for (i = 0; i < st->num_channels; i++) {
> +		switch (st->channel_modes[i]) {
> +		case CH_MODE_DAC:
> +			dac |= BIT(i);
> +			break;
> +
> +		case CH_MODE_ADC:
> +			adc |= BIT(i);
> +			break;
> +
> +		case CH_MODE_DAC_AND_ADC:
> +			dac |= BIT(i);
> +			adc |= BIT(i);
> +			break;
> +
> +		case CH_MODE_GPIO:
> +			st->gpio_map |= BIT(i);
> +			st->gpio_in |= BIT(i); /* Default to input */
> +			break;
> +
> +		case CH_MODE_UNUSED:
> +			/* fall-through */
> +		default:
> +			switch (st->channel_offstate[i]) {
> +			case CH_OFFSTATE_OUT_TRISTATE:
> +				tristate |= BIT(i);
> +				break;
> +
> +			case CH_OFFSTATE_OUT_LOW:
> +				st->gpio_out |= BIT(i);
> +				break;
> +
> +			case CH_OFFSTATE_OUT_HIGH:
> +				st->gpio_out |= BIT(i);
> +				st->gpio_val |= BIT(i);
> +				break;
> +
> +			case CH_OFFSTATE_PULLDOWN:
> +				/* fall-through */
> +			default:
> +				pulldown |= BIT(i);
> +				break;
> +			}
> +		}
> +	}
> +
> +	mutex_lock(&iio_dev->mlock);
> +
> +	/* Pull down unused pins to GND */
> +	ret = ops->reg_write(st, AD5592R_REG_PULLDOWN, pulldown);
> +	if (ret)
> +		goto err_unlock;
> +
> +	ret = ops->reg_write(st, AD5592R_REG_TRISTATE, tristate);
> +	if (ret)
> +		goto err_unlock;
> +
> +	/* 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_SET, st->gpio_val);
> +	if (ret)
> +		goto err_unlock;
> +
> +	ret = ops->reg_write(st, AD5592R_REG_GPIO_OUT_EN, st->gpio_out);
> +	if (ret)
> +		goto err_unlock;
> +
> +	ret = ops->reg_write(st, AD5592R_REG_GPIO_IN_EN, st->gpio_in);
> +	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_reset_channel_modes(struct ad5592r_state *st)
> +{
> +	int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(st->channel_modes); i++)
> +		st->channel_modes[i] = CH_MODE_UNUSED;
> +
> +	return ad5592r_set_channel_modes(st);
> +}
> +
> +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;
> +
> +		if (!chan->output)
> +			return -EINVAL;
> +
> +		mutex_lock(&iio_dev->mlock);
> +		ret = st->ops->write_dac(st, chan->channel, val);
> +		if (!ret)
> +			st->cached_dac[chan->channel] = val;
> +		mutex_unlock(&iio_dev->mlock);
> +		return ret;
> +	case IIO_CHAN_INFO_SCALE:
> +		if (chan->type == IIO_VOLTAGE) {
> +			bool gain;
> +
> +			if (val == st->scale_avail[0][0] &&
> +				val2 == st->scale_avail[0][1])
> +				gain = false;
> +			else if (val == st->scale_avail[1][0] &&
> +				 val2 == st->scale_avail[1][1])
> +				gain = true;
> +			else
> +				return -EINVAL;
> +
> +			mutex_lock(&iio_dev->mlock);
> +
> +			ret = st->ops->reg_read(st, AD5592R_REG_CTRL,
> +						&st->cached_gp_ctrl);
> +			if (ret < 0) {
> +				mutex_unlock(&iio_dev->mlock);
> +				return ret;
> +			}
> +
> +			if (chan->output) {
> +				if (gain)
> +					st->cached_gp_ctrl |=
> +						AD5592R_REG_CTRL_DAC_RANGE;
> +				else
> +					st->cached_gp_ctrl &=
> +						~AD5592R_REG_CTRL_DAC_RANGE;
> +			} else {
> +				if (gain)
> +					st->cached_gp_ctrl |=
> +						AD5592R_REG_CTRL_ADC_RANGE;
> +				else
> +					st->cached_gp_ctrl &=
> +						~AD5592R_REG_CTRL_ADC_RANGE;
> +			}
> +
> +			ret = st->ops->reg_write(st, AD5592R_REG_CTRL,
> +						 st->cached_gp_ctrl);
> +			mutex_unlock(&iio_dev->mlock);
> +			if (ret < 0)
> +				return ret;
> +
> +			return ret;
> +
> +		}
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +
> +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);
> +
> +		if (!chan->output) {
> +			ret = st->ops->read_adc(st, chan->channel, &read_val);
> +			if (ret)
> +				goto unlock;
> +
> +			if ((read_val >> 12 & 0x7) != (chan->channel & 0x7)) {
> +				dev_err(st->dev, "Error while reading channel %u\n",
> +						chan->channel);
> +				ret = -EIO;
> +				goto unlock;
> +			}
> +
> +			read_val &= GENMASK(11, 0);
> +
> +		} else {
> +			read_val = st->cached_dac[chan->channel];
> +		}
> +
> +		dev_dbg(st->dev, "Channel %u read: 0x%04hX\n",
> +				chan->channel, read_val);
> +
> +		*val = (int) read_val;
> +		ret = IIO_VAL_INT;
> +		break;
> +	case IIO_CHAN_INFO_SCALE:
> +		*val = ad5592r_get_vref(st);
> +
> +		if (chan->type == IIO_TEMP) {
> +			s64 tmp = *val * (3767897513LL / 25LL);
> +			*val = div_s64_rem(tmp, 1000000000LL, val2);
> +
> +			ret = IIO_VAL_INT_PLUS_MICRO;
> +		} else {
> +			int mult;
> +
> +			mutex_lock(&iio_dev->mlock);
> +
> +			if (chan->output)
> +				mult = !!(st->cached_gp_ctrl &
> +					AD5592R_REG_CTRL_DAC_RANGE);
> +			else
> +				mult = !!(st->cached_gp_ctrl &
> +					AD5592R_REG_CTRL_ADC_RANGE);
> +
> +			*val *= ++mult;
> +
> +			*val2 = chan->scan_type.realbits;
> +			ret = IIO_VAL_FRACTIONAL_LOG2;
> +		}
> +		break;
> +	case IIO_CHAN_INFO_OFFSET:
> +		ret = ad5592r_get_vref(st);
> +
> +		mutex_lock(&iio_dev->mlock);
> +
> +		if (st->cached_gp_ctrl & AD5592R_REG_CTRL_ADC_RANGE)
> +			*val = (-34365 * 25) / ret;
> +		else
> +			*val = (-75365 * 25) / ret;
> +		ret =  IIO_VAL_INT;
> +		break;
> +	default:
> +		ret = -EINVAL;
> +	}
> +
> +unlock:
> +	mutex_unlock(&iio_dev->mlock);
> +	return ret;
> +}
> +
> +static int ad5592r_write_raw_get_fmt(struct iio_dev *indio_dev,
> +				 struct iio_chan_spec const *chan, long mask)
> +{
> +	switch (mask) {
> +	case IIO_CHAN_INFO_SCALE:
> +		return IIO_VAL_INT_PLUS_NANO;
> +
> +	default:
> +		return IIO_VAL_INT_PLUS_MICRO;
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static const struct iio_info ad5592r_info = {
> +	.read_raw = ad5592r_read_raw,
> +	.write_raw = ad5592r_write_raw,
> +	.write_raw_get_fmt = ad5592r_write_raw_get_fmt,
> +	.driver_module = THIS_MODULE,
> +};
> +
> +static ssize_t ad5592r_show_scale_available(struct iio_dev *iio_dev,
> +					   uintptr_t private,
> +					   const struct iio_chan_spec *chan,
> +					   char *buf)
> +{
> +	struct ad5592r_state *st = iio_priv(iio_dev);
> +
> +	return sprintf(buf, "%d.%09u %d.%09u\n",
> +		st->scale_avail[0][0], st->scale_avail[0][1],
> +		st->scale_avail[1][0], st->scale_avail[1][1]);
> +}
> +
> +static struct iio_chan_spec_ext_info ad5592r_ext_info[] = {
> +	{
> +	 .name = "scale_available",
> +	 .read = ad5592r_show_scale_available,
> +	 .shared = true,
> +	 },
> +	{},
> +};
> +
> +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->info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE);
> +	chan->scan_type.sign = 'u';
> +	chan->scan_type.realbits = 12;
> +	chan->scan_type.storagebits = 16;
> +	chan->ext_info = ad5592r_ext_info;
> +}
> +
> +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;
> +	struct fwnode_handle *child;
> +	u32 reg, tmp;
> +	int ret;
> +
> +	device_for_each_child_node(st->dev, child) {
> +		ret = fwnode_property_read_u32(child, "reg", &reg);
> +		if (ret || reg > ARRAY_SIZE(st->channel_modes))
> +			continue;
> +
> +		ret = fwnode_property_read_u32(child, "adi,mode", &tmp);
> +		if (!ret)
> +			st->channel_modes[reg] = tmp;
> +
> +		fwnode_property_read_u32(child, "adi,off-state", &tmp);
> +		if (!ret)
> +			st->channel_offstate[reg] = tmp;
> +	}
> +
> +	channels = devm_kzalloc(st->dev,
> +			(1 + 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, i);
> +			curr_channel++;
> +			break;
> +
> +		case CH_MODE_ADC:
> +			ad5592r_setup_channel(iio_dev, &channels[curr_channel],
> +					false, i);
> +			curr_channel++;
> +			break;
> +
> +		case CH_MODE_DAC_AND_ADC:
> +			ad5592r_setup_channel(iio_dev, &channels[curr_channel],
> +					true, i);
> +			curr_channel++;
> +			ad5592r_setup_channel(iio_dev, &channels[curr_channel],
> +					false, i);
> +			curr_channel++;
> +			break;
> +
> +		default:
> +			continue;
> +		}
> +	}
> +
> +	channels[curr_channel].type = IIO_TEMP;
> +	channels[curr_channel].channel = 8;
> +	channels[curr_channel].info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> +				   BIT(IIO_CHAN_INFO_SCALE) |
> +				   BIT(IIO_CHAN_INFO_OFFSET);
> +	curr_channel++;
> +
> +	iio_dev->num_channels = curr_channel;
> +	iio_dev->channels = channels;
> +
> +	return 0;
> +}
> +
> +static void ad5592r_init_scales(struct ad5592r_state *st, int vref_mV)
> +{
> +	s64 tmp = (s64)vref_mV * 1000000000LL >> 12;
> +
> +	st->scale_avail[0][0] =
> +		div_s64_rem(tmp, 1000000000LL, &st->scale_avail[0][1]);
> +	st->scale_avail[1][0] =
> +		div_s64_rem(tmp * 2, 1000000000LL, &st->scale_avail[1][1]);
> +}
> +
> +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);
> +
> +	st->reg = devm_regulator_get_optional(dev, "vref");
> +	if (IS_ERR(st->reg)) {
 > +		if ((PTR_ERR(st->reg) != -ENODEV) && dev->of_node)
> +			return PTR_ERR(st->reg);
> +
> +		st->reg = NULL;
> +	} else {
> +		ret = regulator_enable(st->reg);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	iio_dev->dev.parent = dev;
> +	iio_dev->name = name;
> +	iio_dev->info = &ad5592r_info;
> +	iio_dev->modes = INDIO_DIRECT_MODE;
> +
> +	ad5592r_init_scales(st, ad5592r_get_vref(st));
> +
> +	ret = ad5592r_reset(st);
> +	if (ret)
> +		goto error_disable_reg;
> +
> +	ret = ops->reg_write(st, AD5592R_REG_PD,
> +		     (st->reg == NULL) ? AD5592R_REG_PD_EN_REF : 0);
> +	if (ret)
> +		goto error_disable_reg;
> +
> +	ret = ad5592r_alloc_channels(st);
> +	if (ret)
> +		goto error_disable_reg;
> +
> +	ret = ad5592r_set_channel_modes(st);
> +	if (ret)
> +		goto error_reset_ch_modes;
> +
> +	ret = iio_device_register(iio_dev);
> +	if (ret)
> +		goto error_reset_ch_modes;
> +
> +	ret = ad5592r_gpio_init(st);
> +	if (ret)
> +		goto error_dev_unregister;
> +
> +	return 0;
> +
> +error_dev_unregister:
> +	iio_device_unregister(iio_dev);
> +
> +error_reset_ch_modes:
> +	ad5592r_reset_channel_modes(st);
> +
> +error_disable_reg:
> +	if (st->reg)
> +		regulator_disable(st->reg);
> +
> +	return ret;
> +}
> +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);
> +
> +	iio_device_unregister(iio_dev);
> +	ad5592r_gpio_cleanup(st);
It's a small point, but you should ideally reorder the above so that
they are in the reverse of the ordering in probe.  Just makes it more
obviously correct (even when there clearly isn't a real problem like here!)
> +	ad5592r_reset_channel_modes(st);
> +
> +	if (st->reg)
> +		regulator_disable(st->reg);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(ad5592r_remove);
> +
> +MODULE_AUTHOR("Paul Cercueil <paul.cercueil@analog.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..2753385
> --- /dev/null
> +++ b/drivers/iio/dac/ad5592r-base.h
> @@ -0,0 +1,78 @@
> +/*
> + * AD5592R / AD5593R Digital <-> Analog converters driver
> + *
> + * Copyright 2015-2016 Analog Devices Inc.
> + * Author: Paul Cercueil <paul.cercueil@analog.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>
> +#include <linux/mutex.h>
> +#include <linux/gpio/driver.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,
> +};
> +
> +#define AD5592R_REG_PD_EN_REF		BIT(9)
> +#define AD5592R_REG_CTRL_ADC_RANGE	BIT(5)
> +#define AD5592R_REG_CTRL_DAC_RANGE	BIT(4)
> +
> +struct ad5592r_rw_ops {
> +	int (*write_dac)(struct ad5592r_state *st, unsigned chan, u16 value);
> +	int (*read_adc)(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);
> +	int (*gpio_read)(struct ad5592r_state *st, u8 *value);
> +};
> +
> +struct ad5592r_state {
> +	struct device *dev;
> +	struct regulator *reg;
> +#ifdef CONFIG_GPIOLIB
> +	struct gpio_chip gpiochip;
> +	struct mutex gpio_lock;	/* Protect cached gpio_out, gpio_val, etc. */
> +#endif
> +	unsigned int num_channels;
> +	const struct ad5592r_rw_ops *ops;
> +	int scale_avail[2][2];
> +	u16 cached_dac[8];
> +	u16 cached_gp_ctrl;
> +	u8 channel_modes[8];
> +	u8 channel_offstate[8];
> +	u8 gpio_map;
> +	u8 gpio_out;
> +	u8 gpio_in;
> +	u8 gpio_val;
> +
> +	__be16 spi_msg ____cacheline_aligned;
> +	__be16 spi_msg_nop;
> +};
> +
> +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..0b235a2
> --- /dev/null
> +++ b/drivers/iio/dac/ad5592r.c
> @@ -0,0 +1,164 @@
> +/*
> + * AD5592R Digital <-> Analog converters driver
> + *
> + * Copyright 2015-2016 Analog Devices Inc.
> + * Author: Paul Cercueil <paul.cercueil@analog.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>
> +
> +#define AD5592R_GPIO_READBACK_EN	BIT(10)
> +#define AD5592R_LDAC_READBACK_EN	BIT(6)
> +
> +static int ad5592r_spi_wnop_r16(struct ad5592r_state *st, u16 *buf)
> +{
> +	struct spi_device *spi = container_of(st->dev, struct spi_device, dev);
> +	struct spi_transfer t = {
> +			.tx_buf	= &st->spi_msg_nop,
> +			.rx_buf	= buf,
> +			.len = 2
> +		};
> +
> +	st->spi_msg_nop = 0; /* NOP */
> +
> +	return spi_sync_transfer(spi, &t, 1);
> +}
> +
> +static int ad5592r_write_dac(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_read_adc(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:
> +	 * See Figure 40. Single-Channel ADC Conversion Sequence
> +	 */
> +	ret = ad5592r_spi_wnop_r16(st, &st->spi_msg);
> +	if (ret)
> +		return ret;
> +
> +	ret = ad5592r_spi_wnop_r16(st, &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) |
> +				   AD5592R_LDAC_READBACK_EN | (reg << 2));
> +
> +	ret = spi_write(spi, &st->spi_msg, sizeof(st->spi_msg));
> +	if (ret)
> +		return ret;
> +
> +	ret = ad5592r_spi_wnop_r16(st, &st->spi_msg);
> +	if (ret)
> +		return ret;
> +
> +	*value = be16_to_cpu(st->spi_msg);
> +
> +	return 0;
> +}
> +
> +static int ad5593r_gpio_read(struct ad5592r_state *st, u8 *value)
> +{
> +	int ret;
> +
> +	ret = ad5592r_reg_write(st, AD5592R_REG_GPIO_IN_EN,
> +				AD5592R_GPIO_READBACK_EN | st->gpio_in);
> +	if (ret)
> +		return ret;
> +
> +	ret = ad5592r_spi_wnop_r16(st, &st->spi_msg);
> +	if (ret)
> +		return ret;
> +
> +	*value = (u8) be16_to_cpu(st->spi_msg);
> +
> +	return 0;
> +}
> +
> +static const struct ad5592r_rw_ops ad5592r_rw_ops = {
> +	.write_dac = ad5592r_write_dac,
> +	.read_adc = ad5592r_read_adc,
> +	.reg_write = ad5592r_reg_write,
> +	.reg_read = ad5592r_reg_read,
> +	.gpio_read = ad5593r_gpio_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@analog.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..dca158a
> --- /dev/null
> +++ b/drivers/iio/dac/ad5593r.c
> @@ -0,0 +1,131 @@
> +/*
> + * AD5593R Digital <-> Analog converters driver
> + *
> + * Copyright 2015-2016 Analog Devices Inc.
> + * Author: Paul Cercueil <paul.cercueil@analog.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_write_dac(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_read_adc(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;
> +
> +	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 int ad5593r_gpio_read(struct ad5592r_state *st, u8 *value)
> +{
> +	struct i2c_client *i2c = to_i2c_client(st->dev);
> +	s32 val;
> +
> +	val = i2c_smbus_read_word_swapped(i2c, AD5593R_MODE_GPIO_READBACK);
> +	if (val < 0)
> +		return (int) val;
> +
> +	*value = (u8) val;
> +
> +	return 0;
> +}
> +
> +static const struct ad5592r_rw_ops ad5593r_rw_ops = {
> +	.write_dac = ad5593r_write_dac,
> +	.read_adc = ad5593r_read_adc,
> +	.reg_write = ad5593r_reg_write,
> +	.reg_read = ad5593r_reg_read,
> +	.gpio_read = ad5593r_gpio_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@analog.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..c48aca1
> --- /dev/null
> +++ b/include/dt-bindings/iio/adi,ad5592r.h
> @@ -0,0 +1,16 @@
> +
> +#ifndef _DT_BINDINGS_ADI_AD5592R_H
> +#define _DT_BINDINGS_ADI_AD5592R_H
> +
> +#define CH_MODE_UNUSED			0
> +#define CH_MODE_ADC			1
> +#define CH_MODE_DAC			2
> +#define CH_MODE_DAC_AND_ADC		3
> +#define CH_MODE_GPIO			8
> +
> +#define CH_OFFSTATE_PULLDOWN		0
> +#define CH_OFFSTATE_OUT_LOW		1
> +#define CH_OFFSTATE_OUT_HIGH		2
> +#define CH_OFFSTATE_OUT_TRISTATE	3
> +
> +#endif /* _DT_BINDINGS_ADI_AD5592R_H */
> 

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On 03/05/2016 05:29 AM, Rob Herring wrote:
> On Thu, Mar 03, 2016 at 01:58:03PM +0100, michael.hennerich@analog.com wrote:
>> From: Paul Cercueil <paul.cercueil@analog.com>
>>
>> This patch adds support for the AD5592R (spi) and AD5593R (i2c)
>> ADC/DAC devices.
>>
>> Signed-off-by: Paul Cercueil <paul.cercueil@analog.com>
>> Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
>
> [...]
>
>> +AD5592R Example:
>> +
>> +	#include <dt-bindings/iio/adi,ad5592r.h>
>> +
>> +	vref: regulator-vref {
>> +		compatible = "regulator-fixed";
>> +		regulator-name = "vref-ad559x";
>> +		regulator-min-microvolt = <3300000>;
>> +		regulator-max-microvolt = <3300000>;
>> +		regulator-always-on;
>> +	};
>> +
>> +	ad5592r@0 {
>> +		#size-cells = <0>;
>> +		#address-cells = <1>;
>> +		compatible = "adi,ad5592r";
>> +		reg = <0>;
>> +		spi-max-frequency = <1000000>;
>> +		spi-cpol;
>> +
>> +		vref-supply = <&vref>; /* optional */
>> +		reset-gpios = <&gpio0 86 0>;  /* optional */
>> +
>> +		channel@0 {
>> +			reg = <0>;
>> +			mode = <CH_MODE_DAC>;
>
> You are missing the vendor prefixes thoughout.
>

Thanks

Right - I'll fix this ASAP.

On 03/05/2016 03:32 PM, Jonathan Cameron wrote:
> On 03/03/16 12:58, michael.hennerich@analog.com wrote:
>> From: Paul Cercueil <paul.cercueil@analog.com>
>>
>> This patch adds support for the AD5592R (spi) and AD5593R (i2c)
>> ADC/DAC devices.
>>
>> Signed-off-by: Paul Cercueil <paul.cercueil@analog.com>
>> Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
>>
>> Changes since v1:
>> 	* Fix mutex usage
>> 	* Remove unnecessary NULL pointer guards
>> 	* Add comment explaining the invalid data read
>> 	* AD5593R Remove surplus adc readback
>>
>> Changes since v2:
>> 	* Use child nodes to describe channels
>> 	* Fix probe return and driver remove path
>> 	* Move locking closer to where its used
>> 	* Remove WARN_ON but return error
>> 	* Remove OPEN DRAIN configuration option
> Why? I don't particularly mind as of course you aren't obliged to support
> every option in a driver, but I'm curious ;)

I'm not aware that someone asked for that feature.
Supporting it the proper way requires a new GPIOF flag for gpiolib, 
which we can still discuss later, in case someone asks for it.


>
> Otherwise, one minor rearrangement in the remove function would tidy up
> the ordering a little + obviously Rob's binding example comment to be cleaned
> up.
>
> I'd also like a gpio chip ack.   Plenty of time now as the merge window
> for IIO is pretty much closed for this cycle now anyway (probably!)

I'll send the updated patch anyway.

>
> Jonathan
>>
>> ---
>> ---
>>   .../devicetree/bindings/iio/dac/ad5592r.txt        | 143 +++++
>>   drivers/iio/dac/Kconfig                            |  27 +
>>   drivers/iio/dac/Makefile                           |   3 +
>>   drivers/iio/dac/ad5592r-base.c                     | 702 +++++++++++++++++++++
>>   drivers/iio/dac/ad5592r-base.h                     |  78 +++
>>   drivers/iio/dac/ad5592r.c                          | 164 +++++
>>   drivers/iio/dac/ad5593r.c                          | 131 ++++
>>   include/dt-bindings/iio/adi,ad5592r.h              |  16 +
>>   8 files changed, 1264 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/iio/dac/ad5592r.txt
>>   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
>>
>> diff --git a/Documentation/devicetree/bindings/iio/dac/ad5592r.txt b/Documentation/devicetree/bindings/iio/dac/ad5592r.txt
>> new file mode 100644
>> index 0000000..8e2530b
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/iio/dac/ad5592r.txt
>> @@ -0,0 +1,143 @@
>> +Analog Devices AD5592R/AD5593R DAC/ADC device driver
>> +
>> +Required properties for the AD5592R:
>> +	- compatible: Must be "adi,ad5592r"
>> +	- reg: SPI chip select number for the device
>> +	- spi-max-frequency: Max SPI frequency to use (< 30000000)
>> +	- spi-cpol: The AD5592R requires inverse clock polarity (CPOL) mode
>> +
>> +Required properties for the AD5593R:
>> +	- compatible: Must be "adi,ad5593r"
>> +	- reg: I2C address of the device
>> +
>> +Required properties for all supported chips:
>> +	- #address-cells: Should be 1.
>> +	- #size-cells: Should be 0.
>> +	- channel nodes:
>> +	  Each child node represents one channel and has the following
>> +	  Required properties:
>> +		* reg: Pin on which this channel is connected to.
>> +		* adi,mode: Mode or function of this channel.
>> +			    Macros specifying the valid values
>> +			    can be found in <dt-bindings/iio/adi,ad5592r.h>.
>> +
>> +			    The following values are currently supported:
>> +				* CH_MODE_UNUSED (the pin is unused)
>> +				* CH_MODE_ADC (the pin is ADC input)
>> +				* CH_MODE_DAC (the pin is DAC output)
>> +				* CH_MODE_DAC_AND_ADC (the pin is DAC output
>> +					but can be monitored by an ADC)
>> +				* CH_MODE_GPIO (the pin is registered
>> +					with GPIOLIB)
> Still feels like this should be me more generic than a adi specific binding.
> The nearest I can come up with elsewhere in the kernel is pinctrl's
> function binding.  I think that would map as something like:
>
> channel@3 {
> 	function = "adc1";
> 	pins = "pin1"
> };
>
> Doesn't really work though so perhaps we need to go with this as it is with a
> view to revisiting the question sometime in the future perhaps.
>> +	 Optional properties:
>> +		* adi,off-state: State of this channel when unused or the
>> +				 device gets removed. Macros specifying the
>> +				 valid values can be found in
>> +				 <dt-bindings/iio/adi,ad5592r.h>.
>> +
>> +				* CH_OFFSTATE_PULLDOWN (the pin is pulled down)
>> +				* CH_OFFSTATE_OUT_LOW  (the pin is output low)
>> +				* CH_OFFSTATE_OUT_HIGH (the pin is output high)
>> +				* CH_OFFSTATE_OUT_TRISTATE (the pin is
>> +					tristated output)
>> +
>> +
>> +Optional properties:
>> +	- vref-supply: Phandle to the external reference voltage supply. This should
>> +	  only be set if there is an external reference voltage connected to the VREF
>> +	  pin. If the property is not set the internal 2.5V reference is used.
>> +	- reset-gpios : GPIO spec for the RESET pin. If specified, it will be
>> +	  asserted during driver probe.
>> +
>> +AD5592R Example:
>> +
>> +	#include <dt-bindings/iio/adi,ad5592r.h>
>> +
>> +	vref: regulator-vref {
>> +		compatible = "regulator-fixed";
>> +		regulator-name = "vref-ad559x";
>> +		regulator-min-microvolt = <3300000>;
>> +		regulator-max-microvolt = <3300000>;
>> +		regulator-always-on;
>> +	};
>> +
>> +	ad5592r@0 {
>> +		#size-cells = <0>;
>> +		#address-cells = <1>;
>> +		compatible = "adi,ad5592r";
>> +		reg = <0>;
>> +		spi-max-frequency = <1000000>;
>> +		spi-cpol;
>> +
>> +		vref-supply = <&vref>; /* optional */
>> +		reset-gpios = <&gpio0 86 0>;  /* optional */
>> +
>> +		channel@0 {
>> +			reg = <0>;
>> +			mode = <CH_MODE_DAC>;
>> +		};
>> +		channel@1 {
>> +			reg = <1>;
>> +			mode = <CH_MODE_ADC>;
>> +		};
>> +		channel@2 {
>> +			reg = <2>;
>> +			mode = <CH_MODE_DAC_AND_ADC>;
>> +		};
>> +		channel@3 {
>> +			reg = <3>;
>> +			mode = <CH_MODE_DAC_AND_ADC>;
>> +			offstate = <CH_OFFSTATE_PULLDOWN>;
>> +		};
>> +		channel@4 {
>> +			reg = <4>;
>> +			mode = <CH_MODE_UNUSED>;
>> +			offstate = <CH_OFFSTATE_PULLDOWN>;
>> +		};
>> +		channel@5 {
>> +			reg = <5>;
>> +			mode = <CH_MODE_GPIO>;
>> +			offstate = <CH_OFFSTATE_PULLDOWN>;
>> +		};
>> +		channel@6 {
>> +			reg = <6>;
>> +			mode = <CH_MODE_GPIO>;
>> +			offstate = <CH_OFFSTATE_PULLDOWN>;
>> +		};
>> +		channel@7 {
>> +			reg = <7>;
>> +			mode = <CH_MODE_GPIO>;
>> +			offstate = <CH_OFFSTATE_PULLDOWN>;
>> +		};
>> +	};
>> +
>> +AD5593R Example:
>> +
>> +	#include <dt-bindings/iio/adi,ad5592r.h>
>> +
>> +	ad5593r@10 {
>> +		#size-cells = <0>;
>> +		#address-cells = <1>;
>> +		compatible = "adi,ad5593r";
>> +		reg = <0x10>;
>> +		channel@0 {
>> +			reg = <0>;
>> +			mode = <CH_MODE_DAC>;
>> +			offstate = <CH_OFFSTATE_PULLDOWN>;
>> +		};
>> +		channel@1 {
>> +			reg = <1>;
>> +			mode = <CH_MODE_ADC>;
>> +			offstate = <CH_OFFSTATE_PULLDOWN>;
>> +		};
>> +		channel@2 {
>> +			reg = <2>;
>> +			mode = <CH_MODE_DAC_AND_ADC>;
>> +			offstate = <CH_OFFSTATE_PULLDOWN>;
>> +		};
>> +		channel@6 {
>> +			reg = <6>;
>> +			mode = <CH_MODE_GPIO>;
>> +			offstate = <CH_OFFSTATE_PULLDOWN>;
>> +		};
>> +	};
>> diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
>> index a995139..8c78ece 100644
>> --- a/drivers/iio/dac/Kconfig
>> +++ b/drivers/iio/dac/Kconfig
>> @@ -74,6 +74,33 @@ 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 67b4842..de28cd2 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-$(CONFIG_AD5761) += ad5761.o
>>   obj-$(CONFIG_AD5764) += ad5764.o
>> diff --git a/drivers/iio/dac/ad5592r-base.c b/drivers/iio/dac/ad5592r-base.c
>> new file mode 100644
>> index 0000000..8fb3b23
>> --- /dev/null
>> +++ b/drivers/iio/dac/ad5592r-base.c
>> @@ -0,0 +1,702 @@
>> +/*
>> + * AD5592R Digital <-> Analog converters driver
>> + *
>> + * Copyright 2014-2016 Analog Devices Inc.
>> + * Author: Paul Cercueil <paul.cercueil@analog.com>
>> + *
>> + * Licensed under the GPL-2.
>> + */
>> +
>> +#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>
>> +#include <linux/regulator/consumer.h>
>> +#include <linux/gpio/consumer.h>
>> +#include <linux/gpio/driver.h>
>> +#include <linux/gpio.h>
>> +#include <linux/property.h>
>> +
>> +#include <dt-bindings/iio/adi,ad5592r.h>
>> +
>> +#include "ad5592r-base.h"
>> +
>> +#ifdef CONFIG_GPIOLIB
>> +
>> +static int ad5592r_gpio_get(struct gpio_chip *chip, unsigned offset)
>> +{
>> +	struct ad5592r_state *st = gpiochip_get_data(chip);
>> +	int ret = 0;
>> +	u8 val;
>> +
>> +	mutex_lock(&st->gpio_lock);
>> +
>> +	if (st->gpio_out & BIT(offset))
>> +		val = st->gpio_val;
>> +	else
>> +		ret = st->ops->gpio_read(st, &val);
>> +
>> +	mutex_unlock(&st->gpio_lock);
>> +
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	return !!(val & BIT(offset));
>> +}
>> +
>> +static void ad5592r_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
>> +{
>> +	struct ad5592r_state *st = gpiochip_get_data(chip);
>> +
>> +	mutex_lock(&st->gpio_lock);
>> +
>> +	if (value)
>> +		st->gpio_val |= BIT(offset);
>> +	else
>> +		st->gpio_val &= ~BIT(offset);
>> +
>> +	st->ops->reg_write(st, AD5592R_REG_GPIO_SET, st->gpio_val);
>> +
>> +	mutex_unlock(&st->gpio_lock);
>> +}
>> +
>> +static int ad5592r_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
>> +{
>> +	struct ad5592r_state *st = gpiochip_get_data(chip);
>> +	int ret;
>> +
>> +	mutex_lock(&st->gpio_lock);
>> +
>> +	st->gpio_out &= ~BIT(offset);
>> +	st->gpio_in |= BIT(offset);
>> +
>> +	ret = st->ops->reg_write(st, AD5592R_REG_GPIO_OUT_EN, st->gpio_out);
>> +	if (ret < 0)
>> +		goto err_unlock;
>> +
>> +	ret = st->ops->reg_write(st, AD5592R_REG_GPIO_IN_EN, st->gpio_in);
>> +
>> +err_unlock:
>> +	mutex_unlock(&st->gpio_lock);
>> +
>> +	return ret;
>> +}
>> +
>> +static int ad5592r_gpio_direction_output(struct gpio_chip *chip,
>> +					 unsigned offset, int value)
>> +{
>> +	struct ad5592r_state *st = gpiochip_get_data(chip);
>> +	int ret;
>> +
>> +	mutex_lock(&st->gpio_lock);
>> +
>> +	if (value)
>> +		st->gpio_val |= BIT(offset);
>> +	else
>> +		st->gpio_val &= ~BIT(offset);
>> +
>> +	st->gpio_in &= ~BIT(offset);
>> +	st->gpio_out |= BIT(offset);
>> +
>> +	ret = st->ops->reg_write(st, AD5592R_REG_GPIO_SET, st->gpio_val);
>> +	if (ret < 0)
>> +		goto err_unlock;
>> +
>> +	ret = st->ops->reg_write(st, AD5592R_REG_GPIO_OUT_EN, st->gpio_out);
>> +	if (ret < 0)
>> +		goto err_unlock;
>> +
>> +	ret = st->ops->reg_write(st, AD5592R_REG_GPIO_IN_EN, st->gpio_in);
>> +
>> +err_unlock:
>> +	mutex_unlock(&st->gpio_lock);
>> +
>> +	return ret;
>> +}
>> +
>> +static int ad5592r_gpio_request(struct gpio_chip *chip, unsigned offset)
>> +{
>> +	struct ad5592r_state *st = gpiochip_get_data(chip);
>> +
>> +	if (!(st->gpio_map & BIT(offset))) {
>> +		dev_err(st->dev, "GPIO %d is reserved by alternate function\n",
>> +			offset);
>> +		return -ENODEV;
>> +	}
>> +
>> +	if (offset >= chip->ngpio)
>> +		return -EINVAL;
>> +
>> +	return 0;
>> +}
>> +
>> +static int ad5592r_gpio_init(struct ad5592r_state *st)
>> +{
>> +	if (!st->gpio_map)
>> +		return 0;
>> +
>> +	st->gpiochip.label = dev_name(st->dev);
>> +	st->gpiochip.base = -1;
>> +	st->gpiochip.ngpio = 8;
>> +	st->gpiochip.parent = st->dev;
>> +	st->gpiochip.can_sleep = true;
>> +	st->gpiochip.direction_input = ad5592r_gpio_direction_input;
>> +	st->gpiochip.direction_output = ad5592r_gpio_direction_output;
>> +	st->gpiochip.get = ad5592r_gpio_get;
>> +	st->gpiochip.set = ad5592r_gpio_set;
>> +	st->gpiochip.request = ad5592r_gpio_request;
>> +	st->gpiochip.owner = THIS_MODULE;
>> +
>> +	mutex_init(&st->gpio_lock);
>> +
>> +	return gpiochip_add_data(&st->gpiochip, st);
>> +}
>> +
>> +static void ad5592r_gpio_cleanup(struct ad5592r_state *st)
>> +{
>> +	if (st->gpio_map)
>> +		gpiochip_remove(&st->gpiochip);
>> +}
>> +#else
>> +static int ad5592r_gpio_init(struct ad5592r_state *st) { return 0 };
>> +static void ad5592r_gpio_cleanup(struct ad5592r_state *st) { };
>> +#endif /* CONFIG_GPIOLIB */
>> +
>> +static int ad5592r_reset(struct ad5592r_state *st)
>> +{
>> +	struct gpio_desc *gpio;
>> +	struct iio_dev *iio_dev = iio_priv_to_dev(st);
>> +
>> +	gpio = devm_gpiod_get_optional(st->dev, "reset", GPIOD_OUT_LOW);
>> +	if (IS_ERR(gpio))
>> +		return PTR_ERR(gpio);
>> +
>> +	if (gpio) {
>> +		udelay(1);
>> +		gpiod_set_value(gpio, 1);
>> +	} else {
>> +		mutex_lock(&iio_dev->mlock);
>> +		st->ops->reg_write(st, AD5592R_REG_RESET, 0xdac);
>> +		mutex_unlock(&iio_dev->mlock);
>> +	}
>> +
>> +	udelay(250);
>> +
>> +	return 0;
>> +}
>> +
>> +static int ad5592r_get_vref(struct ad5592r_state *st)
>> +{
>> +	int ret;
>> +
>> +	if (st->reg) {
>> +		ret = regulator_get_voltage(st->reg);
>> +		if (ret < 0)
>> +			return ret;
>> +
>> +		return ret / 1000;
>> +	} else {
>> +		return 2500;
>> +	}
>> +}
>> +
>> +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, tristate = 0, dac = 0, adc = 0;
>> +	u16 read_back;
>> +
>> +	for (i = 0; i < st->num_channels; i++) {
>> +		switch (st->channel_modes[i]) {
>> +		case CH_MODE_DAC:
>> +			dac |= BIT(i);
>> +			break;
>> +
>> +		case CH_MODE_ADC:
>> +			adc |= BIT(i);
>> +			break;
>> +
>> +		case CH_MODE_DAC_AND_ADC:
>> +			dac |= BIT(i);
>> +			adc |= BIT(i);
>> +			break;
>> +
>> +		case CH_MODE_GPIO:
>> +			st->gpio_map |= BIT(i);
>> +			st->gpio_in |= BIT(i); /* Default to input */
>> +			break;
>> +
>> +		case CH_MODE_UNUSED:
>> +			/* fall-through */
>> +		default:
>> +			switch (st->channel_offstate[i]) {
>> +			case CH_OFFSTATE_OUT_TRISTATE:
>> +				tristate |= BIT(i);
>> +				break;
>> +
>> +			case CH_OFFSTATE_OUT_LOW:
>> +				st->gpio_out |= BIT(i);
>> +				break;
>> +
>> +			case CH_OFFSTATE_OUT_HIGH:
>> +				st->gpio_out |= BIT(i);
>> +				st->gpio_val |= BIT(i);
>> +				break;
>> +
>> +			case CH_OFFSTATE_PULLDOWN:
>> +				/* fall-through */
>> +			default:
>> +				pulldown |= BIT(i);
>> +				break;
>> +			}
>> +		}
>> +	}
>> +
>> +	mutex_lock(&iio_dev->mlock);
>> +
>> +	/* Pull down unused pins to GND */
>> +	ret = ops->reg_write(st, AD5592R_REG_PULLDOWN, pulldown);
>> +	if (ret)
>> +		goto err_unlock;
>> +
>> +	ret = ops->reg_write(st, AD5592R_REG_TRISTATE, tristate);
>> +	if (ret)
>> +		goto err_unlock;
>> +
>> +	/* 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_SET, st->gpio_val);
>> +	if (ret)
>> +		goto err_unlock;
>> +
>> +	ret = ops->reg_write(st, AD5592R_REG_GPIO_OUT_EN, st->gpio_out);
>> +	if (ret)
>> +		goto err_unlock;
>> +
>> +	ret = ops->reg_write(st, AD5592R_REG_GPIO_IN_EN, st->gpio_in);
>> +	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_reset_channel_modes(struct ad5592r_state *st)
>> +{
>> +	int i;
>> +
>> +	for (i = 0; i < ARRAY_SIZE(st->channel_modes); i++)
>> +		st->channel_modes[i] = CH_MODE_UNUSED;
>> +
>> +	return ad5592r_set_channel_modes(st);
>> +}
>> +
>> +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;
>> +
>> +		if (!chan->output)
>> +			return -EINVAL;
>> +
>> +		mutex_lock(&iio_dev->mlock);
>> +		ret = st->ops->write_dac(st, chan->channel, val);
>> +		if (!ret)
>> +			st->cached_dac[chan->channel] = val;
>> +		mutex_unlock(&iio_dev->mlock);
>> +		return ret;
>> +	case IIO_CHAN_INFO_SCALE:
>> +		if (chan->type == IIO_VOLTAGE) {
>> +			bool gain;
>> +
>> +			if (val == st->scale_avail[0][0] &&
>> +				val2 == st->scale_avail[0][1])
>> +				gain = false;
>> +			else if (val == st->scale_avail[1][0] &&
>> +				 val2 == st->scale_avail[1][1])
>> +				gain = true;
>> +			else
>> +				return -EINVAL;
>> +
>> +			mutex_lock(&iio_dev->mlock);
>> +
>> +			ret = st->ops->reg_read(st, AD5592R_REG_CTRL,
>> +						&st->cached_gp_ctrl);
>> +			if (ret < 0) {
>> +				mutex_unlock(&iio_dev->mlock);
>> +				return ret;
>> +			}
>> +
>> +			if (chan->output) {
>> +				if (gain)
>> +					st->cached_gp_ctrl |=
>> +						AD5592R_REG_CTRL_DAC_RANGE;
>> +				else
>> +					st->cached_gp_ctrl &=
>> +						~AD5592R_REG_CTRL_DAC_RANGE;
>> +			} else {
>> +				if (gain)
>> +					st->cached_gp_ctrl |=
>> +						AD5592R_REG_CTRL_ADC_RANGE;
>> +				else
>> +					st->cached_gp_ctrl &=
>> +						~AD5592R_REG_CTRL_ADC_RANGE;
>> +			}
>> +
>> +			ret = st->ops->reg_write(st, AD5592R_REG_CTRL,
>> +						 st->cached_gp_ctrl);
>> +			mutex_unlock(&iio_dev->mlock);
>> +			if (ret < 0)
>> +				return ret;
>> +
>> +			return ret;
>> +
>> +		}
>> +		break;
>> +	default:
>> +		return -EINVAL;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +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);
>> +
>> +		if (!chan->output) {
>> +			ret = st->ops->read_adc(st, chan->channel, &read_val);
>> +			if (ret)
>> +				goto unlock;
>> +
>> +			if ((read_val >> 12 & 0x7) != (chan->channel & 0x7)) {
>> +				dev_err(st->dev, "Error while reading channel %u\n",
>> +						chan->channel);
>> +				ret = -EIO;
>> +				goto unlock;
>> +			}
>> +
>> +			read_val &= GENMASK(11, 0);
>> +
>> +		} else {
>> +			read_val = st->cached_dac[chan->channel];
>> +		}
>> +
>> +		dev_dbg(st->dev, "Channel %u read: 0x%04hX\n",
>> +				chan->channel, read_val);
>> +
>> +		*val = (int) read_val;
>> +		ret = IIO_VAL_INT;
>> +		break;
>> +	case IIO_CHAN_INFO_SCALE:
>> +		*val = ad5592r_get_vref(st);
>> +
>> +		if (chan->type == IIO_TEMP) {
>> +			s64 tmp = *val * (3767897513LL / 25LL);
>> +			*val = div_s64_rem(tmp, 1000000000LL, val2);
>> +
>> +			ret = IIO_VAL_INT_PLUS_MICRO;
>> +		} else {
>> +			int mult;
>> +
>> +			mutex_lock(&iio_dev->mlock);
>> +
>> +			if (chan->output)
>> +				mult = !!(st->cached_gp_ctrl &
>> +					AD5592R_REG_CTRL_DAC_RANGE);
>> +			else
>> +				mult = !!(st->cached_gp_ctrl &
>> +					AD5592R_REG_CTRL_ADC_RANGE);
>> +
>> +			*val *= ++mult;
>> +
>> +			*val2 = chan->scan_type.realbits;
>> +			ret = IIO_VAL_FRACTIONAL_LOG2;
>> +		}
>> +		break;
>> +	case IIO_CHAN_INFO_OFFSET:
>> +		ret = ad5592r_get_vref(st);
>> +
>> +		mutex_lock(&iio_dev->mlock);
>> +
>> +		if (st->cached_gp_ctrl & AD5592R_REG_CTRL_ADC_RANGE)
>> +			*val = (-34365 * 25) / ret;
>> +		else
>> +			*val = (-75365 * 25) / ret;
>> +		ret =  IIO_VAL_INT;
>> +		break;
>> +	default:
>> +		ret = -EINVAL;
>> +	}
>> +
>> +unlock:
>> +	mutex_unlock(&iio_dev->mlock);
>> +	return ret;
>> +}
>> +
>> +static int ad5592r_write_raw_get_fmt(struct iio_dev *indio_dev,
>> +				 struct iio_chan_spec const *chan, long mask)
>> +{
>> +	switch (mask) {
>> +	case IIO_CHAN_INFO_SCALE:
>> +		return IIO_VAL_INT_PLUS_NANO;
>> +
>> +	default:
>> +		return IIO_VAL_INT_PLUS_MICRO;
>> +	}
>> +
>> +	return -EINVAL;
>> +}
>> +
>> +static const struct iio_info ad5592r_info = {
>> +	.read_raw = ad5592r_read_raw,
>> +	.write_raw = ad5592r_write_raw,
>> +	.write_raw_get_fmt = ad5592r_write_raw_get_fmt,
>> +	.driver_module = THIS_MODULE,
>> +};
>> +
>> +static ssize_t ad5592r_show_scale_available(struct iio_dev *iio_dev,
>> +					   uintptr_t private,
>> +					   const struct iio_chan_spec *chan,
>> +					   char *buf)
>> +{
>> +	struct ad5592r_state *st = iio_priv(iio_dev);
>> +
>> +	return sprintf(buf, "%d.%09u %d.%09u\n",
>> +		st->scale_avail[0][0], st->scale_avail[0][1],
>> +		st->scale_avail[1][0], st->scale_avail[1][1]);
>> +}
>> +
>> +static struct iio_chan_spec_ext_info ad5592r_ext_info[] = {
>> +	{
>> +	 .name = "scale_available",
>> +	 .read = ad5592r_show_scale_available,
>> +	 .shared = true,
>> +	 },
>> +	{},
>> +};
>> +
>> +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->info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE);
>> +	chan->scan_type.sign = 'u';
>> +	chan->scan_type.realbits = 12;
>> +	chan->scan_type.storagebits = 16;
>> +	chan->ext_info = ad5592r_ext_info;
>> +}
>> +
>> +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;
>> +	struct fwnode_handle *child;
>> +	u32 reg, tmp;
>> +	int ret;
>> +
>> +	device_for_each_child_node(st->dev, child) {
>> +		ret = fwnode_property_read_u32(child, "reg", &reg);
>> +		if (ret || reg > ARRAY_SIZE(st->channel_modes))
>> +			continue;
>> +
>> +		ret = fwnode_property_read_u32(child, "adi,mode", &tmp);
>> +		if (!ret)
>> +			st->channel_modes[reg] = tmp;
>> +
>> +		fwnode_property_read_u32(child, "adi,off-state", &tmp);
>> +		if (!ret)
>> +			st->channel_offstate[reg] = tmp;
>> +	}
>> +
>> +	channels = devm_kzalloc(st->dev,
>> +			(1 + 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, i);
>> +			curr_channel++;
>> +			break;
>> +
>> +		case CH_MODE_ADC:
>> +			ad5592r_setup_channel(iio_dev, &channels[curr_channel],
>> +					false, i);
>> +			curr_channel++;
>> +			break;
>> +
>> +		case CH_MODE_DAC_AND_ADC:
>> +			ad5592r_setup_channel(iio_dev, &channels[curr_channel],
>> +					true, i);
>> +			curr_channel++;
>> +			ad5592r_setup_channel(iio_dev, &channels[curr_channel],
>> +					false, i);
>> +			curr_channel++;
>> +			break;
>> +
>> +		default:
>> +			continue;
>> +		}
>> +	}
>> +
>> +	channels[curr_channel].type = IIO_TEMP;
>> +	channels[curr_channel].channel = 8;
>> +	channels[curr_channel].info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
>> +				   BIT(IIO_CHAN_INFO_SCALE) |
>> +				   BIT(IIO_CHAN_INFO_OFFSET);
>> +	curr_channel++;
>> +
>> +	iio_dev->num_channels = curr_channel;
>> +	iio_dev->channels = channels;
>> +
>> +	return 0;
>> +}
>> +
>> +static void ad5592r_init_scales(struct ad5592r_state *st, int vref_mV)
>> +{
>> +	s64 tmp = (s64)vref_mV * 1000000000LL >> 12;
>> +
>> +	st->scale_avail[0][0] =
>> +		div_s64_rem(tmp, 1000000000LL, &st->scale_avail[0][1]);
>> +	st->scale_avail[1][0] =
>> +		div_s64_rem(tmp * 2, 1000000000LL, &st->scale_avail[1][1]);
>> +}
>> +
>> +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);
>> +
>> +	st->reg = devm_regulator_get_optional(dev, "vref");
>> +	if (IS_ERR(st->reg)) {
>   > +		if ((PTR_ERR(st->reg) != -ENODEV) && dev->of_node)
>> +			return PTR_ERR(st->reg);
>> +
>> +		st->reg = NULL;
>> +	} else {
>> +		ret = regulator_enable(st->reg);
>> +		if (ret)
>> +			return ret;
>> +	}
>> +
>> +	iio_dev->dev.parent = dev;
>> +	iio_dev->name = name;
>> +	iio_dev->info = &ad5592r_info;
>> +	iio_dev->modes = INDIO_DIRECT_MODE;
>> +
>> +	ad5592r_init_scales(st, ad5592r_get_vref(st));
>> +
>> +	ret = ad5592r_reset(st);
>> +	if (ret)
>> +		goto error_disable_reg;
>> +
>> +	ret = ops->reg_write(st, AD5592R_REG_PD,
>> +		     (st->reg == NULL) ? AD5592R_REG_PD_EN_REF : 0);
>> +	if (ret)
>> +		goto error_disable_reg;
>> +
>> +	ret = ad5592r_alloc_channels(st);
>> +	if (ret)
>> +		goto error_disable_reg;
>> +
>> +	ret = ad5592r_set_channel_modes(st);
>> +	if (ret)
>> +		goto error_reset_ch_modes;
>> +
>> +	ret = iio_device_register(iio_dev);
>> +	if (ret)
>> +		goto error_reset_ch_modes;
>> +
>> +	ret = ad5592r_gpio_init(st);
>> +	if (ret)
>> +		goto error_dev_unregister;
>> +
>> +	return 0;
>> +
>> +error_dev_unregister:
>> +	iio_device_unregister(iio_dev);
>> +
>> +error_reset_ch_modes:
>> +	ad5592r_reset_channel_modes(st);
>> +
>> +error_disable_reg:
>> +	if (st->reg)
>> +		regulator_disable(st->reg);
>> +
>> +	return ret;
>> +}
>> +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);
>> +
>> +	iio_device_unregister(iio_dev);
>> +	ad5592r_gpio_cleanup(st);
> It's a small point, but you should ideally reorder the above so that
> they are in the reverse of the ordering in probe.  Just makes it more
> obviously correct (even when there clearly isn't a real problem like here!)
>> +	ad5592r_reset_channel_modes(st);
>> +
>> +	if (st->reg)
>> +		regulator_disable(st->reg);
>> +
>> +	return 0;
>> +}
>> +EXPORT_SYMBOL_GPL(ad5592r_remove);
>> +
>> +MODULE_AUTHOR("Paul Cercueil <paul.cercueil@analog.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..2753385
>> --- /dev/null
>> +++ b/drivers/iio/dac/ad5592r-base.h
>> @@ -0,0 +1,78 @@
>> +/*
>> + * AD5592R / AD5593R Digital <-> Analog converters driver
>> + *
>> + * Copyright 2015-2016 Analog Devices Inc.
>> + * Author: Paul Cercueil <paul.cercueil@analog.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>
>> +#include <linux/mutex.h>
>> +#include <linux/gpio/driver.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,
>> +};
>> +
>> +#define AD5592R_REG_PD_EN_REF		BIT(9)
>> +#define AD5592R_REG_CTRL_ADC_RANGE	BIT(5)
>> +#define AD5592R_REG_CTRL_DAC_RANGE	BIT(4)
>> +
>> +struct ad5592r_rw_ops {
>> +	int (*write_dac)(struct ad5592r_state *st, unsigned chan, u16 value);
>> +	int (*read_adc)(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);
>> +	int (*gpio_read)(struct ad5592r_state *st, u8 *value);
>> +};
>> +
>> +struct ad5592r_state {
>> +	struct device *dev;
>> +	struct regulator *reg;
>> +#ifdef CONFIG_GPIOLIB
>> +	struct gpio_chip gpiochip;
>> +	struct mutex gpio_lock;	/* Protect cached gpio_out, gpio_val, etc. */
>> +#endif
>> +	unsigned int num_channels;
>> +	const struct ad5592r_rw_ops *ops;
>> +	int scale_avail[2][2];
>> +	u16 cached_dac[8];
>> +	u16 cached_gp_ctrl;
>> +	u8 channel_modes[8];
>> +	u8 channel_offstate[8];
>> +	u8 gpio_map;
>> +	u8 gpio_out;
>> +	u8 gpio_in;
>> +	u8 gpio_val;
>> +
>> +	__be16 spi_msg ____cacheline_aligned;
>> +	__be16 spi_msg_nop;
>> +};
>> +
>> +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..0b235a2
>> --- /dev/null
>> +++ b/drivers/iio/dac/ad5592r.c
>> @@ -0,0 +1,164 @@
>> +/*
>> + * AD5592R Digital <-> Analog converters driver
>> + *
>> + * Copyright 2015-2016 Analog Devices Inc.
>> + * Author: Paul Cercueil <paul.cercueil@analog.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>
>> +
>> +#define AD5592R_GPIO_READBACK_EN	BIT(10)
>> +#define AD5592R_LDAC_READBACK_EN	BIT(6)
>> +
>> +static int ad5592r_spi_wnop_r16(struct ad5592r_state *st, u16 *buf)
>> +{
>> +	struct spi_device *spi = container_of(st->dev, struct spi_device, dev);
>> +	struct spi_transfer t = {
>> +			.tx_buf	= &st->spi_msg_nop,
>> +			.rx_buf	= buf,
>> +			.len = 2
>> +		};
>> +
>> +	st->spi_msg_nop = 0; /* NOP */
>> +
>> +	return spi_sync_transfer(spi, &t, 1);
>> +}
>> +
>> +static int ad5592r_write_dac(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_read_adc(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:
>> +	 * See Figure 40. Single-Channel ADC Conversion Sequence
>> +	 */
>> +	ret = ad5592r_spi_wnop_r16(st, &st->spi_msg);
>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = ad5592r_spi_wnop_r16(st, &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) |
>> +				   AD5592R_LDAC_READBACK_EN | (reg << 2));
>> +
>> +	ret = spi_write(spi, &st->spi_msg, sizeof(st->spi_msg));
>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = ad5592r_spi_wnop_r16(st, &st->spi_msg);
>> +	if (ret)
>> +		return ret;
>> +
>> +	*value = be16_to_cpu(st->spi_msg);
>> +
>> +	return 0;
>> +}
>> +
>> +static int ad5593r_gpio_read(struct ad5592r_state *st, u8 *value)
>> +{
>> +	int ret;
>> +
>> +	ret = ad5592r_reg_write(st, AD5592R_REG_GPIO_IN_EN,
>> +				AD5592R_GPIO_READBACK_EN | st->gpio_in);
>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = ad5592r_spi_wnop_r16(st, &st->spi_msg);
>> +	if (ret)
>> +		return ret;
>> +
>> +	*value = (u8) be16_to_cpu(st->spi_msg);
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct ad5592r_rw_ops ad5592r_rw_ops = {
>> +	.write_dac = ad5592r_write_dac,
>> +	.read_adc = ad5592r_read_adc,
>> +	.reg_write = ad5592r_reg_write,
>> +	.reg_read = ad5592r_reg_read,
>> +	.gpio_read = ad5593r_gpio_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@analog.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..dca158a
>> --- /dev/null
>> +++ b/drivers/iio/dac/ad5593r.c
>> @@ -0,0 +1,131 @@
>> +/*
>> + * AD5593R Digital <-> Analog converters driver
>> + *
>> + * Copyright 2015-2016 Analog Devices Inc.
>> + * Author: Paul Cercueil <paul.cercueil@analog.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_write_dac(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_read_adc(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;
>> +
>> +	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 int ad5593r_gpio_read(struct ad5592r_state *st, u8 *value)
>> +{
>> +	struct i2c_client *i2c = to_i2c_client(st->dev);
>> +	s32 val;
>> +
>> +	val = i2c_smbus_read_word_swapped(i2c, AD5593R_MODE_GPIO_READBACK);
>> +	if (val < 0)
>> +		return (int) val;
>> +
>> +	*value = (u8) val;
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct ad5592r_rw_ops ad5593r_rw_ops = {
>> +	.write_dac = ad5593r_write_dac,
>> +	.read_adc = ad5593r_read_adc,
>> +	.reg_write = ad5593r_reg_write,
>> +	.reg_read = ad5593r_reg_read,
>> +	.gpio_read = ad5593r_gpio_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@analog.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..c48aca1
>> --- /dev/null
>> +++ b/include/dt-bindings/iio/adi,ad5592r.h
>> @@ -0,0 +1,16 @@
>> +
>> +#ifndef _DT_BINDINGS_ADI_AD5592R_H
>> +#define _DT_BINDINGS_ADI_AD5592R_H
>> +
>> +#define CH_MODE_UNUSED			0
>> +#define CH_MODE_ADC			1
>> +#define CH_MODE_DAC			2
>> +#define CH_MODE_DAC_AND_ADC		3
>> +#define CH_MODE_GPIO			8
>> +
>> +#define CH_OFFSTATE_PULLDOWN		0
>> +#define CH_OFFSTATE_OUT_LOW		1
>> +#define CH_OFFSTATE_OUT_HIGH		2
>> +#define CH_OFFSTATE_OUT_TRISTATE	3
>> +
>> +#endif /* _DT_BINDINGS_ADI_AD5592R_H */
>>
>

On Mon, Mar 7, 2016 at 7:34 PM, Michael Hennerich
<michael.hennerich@analog.com> wrote:
> On 03/05/2016 03:32 PM, Jonathan Cameron wrote:

>>> Changes since v2:
>>>         * Use child nodes to describe channels
>>>         * Fix probe return and driver remove path
>>>         * Move locking closer to where its used
>>>         * Remove WARN_ON but return error
>>>         * Remove OPEN DRAIN configuration option
>>
>> Why? I don't particularly mind as of course you aren't obliged to support
>> every option in a driver, but I'm curious ;)
>
> I'm not aware that someone asked for that feature.
> Supporting it the proper way requires a new GPIOF flag for gpiolib, which we
> can still discuss later, in case someone asks for it.

We have:
include/dt-bindings/gpio/gpio.h

/*
 * Open Drain/Collector is the combination of single-ended active low,
 * Open Source/Emitter is the combination of single-ended active high.
 */
#define GPIO_OPEN_DRAIN (GPIO_SINGLE_ENDED | GPIO_ACTIVE_LOW)
#define GPIO_OPEN_SOURCE (GPIO_SINGLE_ENDED | GPIO_ACTIVE_HIGH)

So consumers can ask (in DT) for a line in open drain mode.

FLAG_OPEN_DRAIN will be set internally in gpiolibs gpio_desc
in of_find_gpio() as a result and it will behave as expected.

Yours,
Linus Walleij
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On 03/11/2016 05:37 PM, Linus Walleij wrote:
> On Mon, Mar 7, 2016 at 7:34 PM, Michael Hennerich
> <michael.hennerich@analog.com> wrote:
>> On 03/05/2016 03:32 PM, Jonathan Cameron wrote:
>
>>>> Changes since v2:
>>>>          * Use child nodes to describe channels
>>>>          * Fix probe return and driver remove path
>>>>          * Move locking closer to where its used
>>>>          * Remove WARN_ON but return error
>>>>          * Remove OPEN DRAIN configuration option
>>>
>>> Why? I don't particularly mind as of course you aren't obliged to support
>>> every option in a driver, but I'm curious ;)
>>
>> I'm not aware that someone asked for that feature.
>> Supporting it the proper way requires a new GPIOF flag for gpiolib, which we
>> can still discuss later, in case someone asks for it.
>
> We have:
> include/dt-bindings/gpio/gpio.h
>
> /*
>   * Open Drain/Collector is the combination of single-ended active low,
>   * Open Source/Emitter is the combination of single-ended active high.
>   */
> #define GPIO_OPEN_DRAIN (GPIO_SINGLE_ENDED | GPIO_ACTIVE_LOW)
> #define GPIO_OPEN_SOURCE (GPIO_SINGLE_ENDED | GPIO_ACTIVE_HIGH)
>
> So consumers can ask (in DT) for a line in open drain mode.
>
> FLAG_OPEN_DRAIN will be set internally in gpiolibs gpio_desc
> in of_find_gpio() as a result and it will behave as expected.
>
> Yours,
> Linus Walleij
>

Hi Linus,

The thing is that the device directly supports an OPEN DRAIN mode.

If the consumer asks for open drain mode - everything works as expected.
However instead of utilizing the on-chip feature, GPIOLIB will emulate 
open drain behaviour by configuring the chip for input when someone 
writes logic high.

So the comment above was really meant to say -
remove on-chip OPEN DRAIN mode, consumers should use the GPIOLIB 
implementation if required.

On Mon, Mar 21, 2016 at 2:48 PM, Michael Hennerich
<michael.hennerich@analog.com> wrote:

> The thing is that the device directly supports an OPEN DRAIN mode.
>
> If the consumer asks for open drain mode - everything works as expected.
> However instead of utilizing the on-chip feature, GPIOLIB will emulate open
> drain behaviour by configuring the chip for input when someone writes logic
> high.
>
> So the comment above was really meant to say -
> remove on-chip OPEN DRAIN mode, consumers should use the GPIOLIB
> implementation if required.

This is very interesting.

So if a hardware has *real* open drain, i.e. a bit in hardware that says
"set me in open drain mode" we should manage this in gpiolib
and provide a special callback in the vtable for it, right? Because it
is certainly better to do this with hardware, if we can.

I'll send a draft patch and we can see if this is what you want.

Yours,
Linus Walleij
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On 22/03/16 08:49, Linus Walleij wrote:
> On Mon, Mar 21, 2016 at 2:48 PM, Michael Hennerich
> <michael.hennerich@analog.com> wrote:
> 
>> The thing is that the device directly supports an OPEN DRAIN mode.
>>
>> If the consumer asks for open drain mode - everything works as expected.
>> However instead of utilizing the on-chip feature, GPIOLIB will emulate open
>> drain behaviour by configuring the chip for input when someone writes logic
>> high.
>>
>> So the comment above was really meant to say -
>> remove on-chip OPEN DRAIN mode, consumers should use the GPIOLIB
>> implementation if required.
> 
> This is very interesting.
> 
> So if a hardware has *real* open drain, i.e. a bit in hardware that says
> "set me in open drain mode" we should manage this in gpiolib
> and provide a special callback in the vtable for it, right? Because it
> is certainly better to do this with hardware, if we can.
H*** yeah.  Funny how open drain stuff is popping up left right and centre
all of a sudden.
> 
> I'll send a draft patch and we can see if this is what you want.
Cool.  I like fast solutions ;)
> 
> Yours,
> Linus Walleij
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