Re: [PATCH v2 2/5] iio: dac: add support for stm32 DAC

[Fabrice Gasnier]

On 04/09/2017 10:39 AM, Jonathan Cameron wrote:
> On 06/04/17 17:11, Fabrice Gasnier wrote:
>> Add support for STMicroelectronics STM32 DAC. It's a 12-bit, voltage
>> output digital-to-analog converter. It has two output channels, each
>> with its own converter.
>> It supports 8 bits or 12bits left/right aligned data format. Only
>> 12bits right-aligned is used here. It has built-in noise or
>> triangle waveform generator, and supports external triggers for
>> conversions.
>> Each channel can be used independently, with separate trigger, then
>> separate IIO devices are used to handle this. Core driver is intended
>> to share common resources such as clock, reset, reference voltage and
>> registers.
>>
>> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@xxxxxx>
> A few little bits and pieces from the change to powerdown modes...
> 
> I have also been thinking about whether we can take this prior to sorting
> out the DDS side, but worry a little that we may end up wanting to change
> the way we define the channels - so that might need sorting to some degree
> before we can get the basics in place.

Hi Jonathan,

Just sent updated v3 with powerdown changes as per your comments.

> 
> Jonathan
>> ---
>> Changes in v2:
>> - Define 'Hi-Z'/'enable' powerdown modes instead of using 'enable'
>>   attribute normally not used for DACs.
>> - use 'reg' instead of 'st,dac-channel' property
>> - Use macro to differentiate channels
>> - Fix typos, remove leading '&' for functions
>> - Add comments on single channel per device
>> - Use devm_iio_device_register variant, removes need for .remove
>> ---
>>  drivers/iio/dac/Kconfig          |  15 ++
>>  drivers/iio/dac/Makefile         |   2 +
>>  drivers/iio/dac/stm32-dac-core.c | 180 ++++++++++++++++++++
>>  drivers/iio/dac/stm32-dac-core.h |  51 ++++++
>>  drivers/iio/dac/stm32-dac.c      | 350 +++++++++++++++++++++++++++++++++++++++
>>  5 files changed, 598 insertions(+)
>>  create mode 100644 drivers/iio/dac/stm32-dac-core.c
>>  create mode 100644 drivers/iio/dac/stm32-dac-core.h
>>  create mode 100644 drivers/iio/dac/stm32-dac.c
>>
>> diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
>> index d3084028..7198648 100644
>> --- a/drivers/iio/dac/Kconfig
>> +++ b/drivers/iio/dac/Kconfig
>> @@ -274,6 +274,21 @@ config MCP4922
>>  	  To compile this driver as a module, choose M here: the module
>>  	  will be called mcp4922.
>>  
>> +config STM32_DAC
>> +	tristate "STMicroelectronics STM32 DAC"
>> +	depends on (ARCH_STM32 && OF) || COMPILE_TEST
>> +	depends on REGULATOR
>> +	select STM32_DAC_CORE
>> +	help
>> +	  Say yes here to build support for STMicroelectronics STM32 Digital
>> +	  to Analog Converter (DAC).
>> +
>> +	  This driver can also be built as a module.  If so, the module
>> +	  will be called stm32-dac.
>> +
>> +config STM32_DAC_CORE
>> +	tristate
>> +
>>  config VF610_DAC
>>  	tristate "Vybrid vf610 DAC driver"
>>  	depends on OF
>> diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile
>> index f01bf4a..afe8ae7 100644
>> --- a/drivers/iio/dac/Makefile
>> +++ b/drivers/iio/dac/Makefile
>> @@ -29,4 +29,6 @@ obj-$(CONFIG_MAX517) += max517.o
>>  obj-$(CONFIG_MAX5821) += max5821.o
>>  obj-$(CONFIG_MCP4725) += mcp4725.o
>>  obj-$(CONFIG_MCP4922) += mcp4922.o
>> +obj-$(CONFIG_STM32_DAC_CORE) += stm32-dac-core.o
>> +obj-$(CONFIG_STM32_DAC) += stm32-dac.o
>>  obj-$(CONFIG_VF610_DAC) += vf610_dac.o
>> diff --git a/drivers/iio/dac/stm32-dac-core.c b/drivers/iio/dac/stm32-dac-core.c
>> new file mode 100644
>> index 0000000..75e4878
>> --- /dev/null
>> +++ b/drivers/iio/dac/stm32-dac-core.c
>> @@ -0,0 +1,180 @@
>> +/*
>> + * This file is part of STM32 DAC driver
>> + *
>> + * Copyright (C) 2017, STMicroelectronics - All Rights Reserved
>> + * Author: Fabrice Gasnier <fabrice.gasnier@xxxxxx>.
>> + *
>> + * License type: GPLv2
>> + *
>> + * This program is free software; you can redistribute it and/or modify it
>> + * under the terms of the GNU General Public License version 2 as published by
>> + * the Free Software Foundation.
>> + *
>> + * This program is distributed in the hope that it will be useful, but
>> + * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
>> + * or FITNESS FOR A PARTICULAR PURPOSE.
>> + * See the GNU General Public License for more details.
>> + *
>> + * You should have received a copy of the GNU General Public License along with
>> + * this program. If not, see <http://www.gnu.org/licenses/>.
>> + */
>> +
>> +#include <linux/clk.h>
>> +#include <linux/delay.h>
>> +#include <linux/module.h>
>> +#include <linux/of_platform.h>
>> +#include <linux/regulator/consumer.h>
>> +#include <linux/reset.h>
>> +
>> +#include "stm32-dac-core.h"
>> +
>> +/**
>> + * struct stm32_dac_priv - stm32 DAC core private data
>> + * @pclk:		peripheral clock common for all DACs
>> + * @rst:		peripheral reset control
>> + * @vref:		regulator reference
>> + * @common:		Common data for all DAC instances
>> + */
>> +struct stm32_dac_priv {
>> +	struct clk *pclk;
>> +	struct reset_control *rst;
>> +	struct regulator *vref;
>> +	struct stm32_dac_common common;
>> +};
>> +
>> +static struct stm32_dac_priv *to_stm32_dac_priv(struct stm32_dac_common *com)
>> +{
>> +	return container_of(com, struct stm32_dac_priv, common);
>> +}
>> +
>> +static const struct regmap_config stm32_dac_regmap_cfg = {
>> +	.reg_bits = 32,
>> +	.val_bits = 32,
>> +	.reg_stride = sizeof(u32),
>> +	.max_register = 0x3fc,
>> +};
>> +
>> +static int stm32_dac_probe(struct platform_device *pdev)
>> +{
>> +	struct device *dev = &pdev->dev;
>> +	struct stm32_dac_priv *priv;
>> +	struct regmap *regmap;
>> +	struct resource *res;
>> +	void __iomem *mmio;
>> +	int ret;
>> +
>> +	if (!dev->of_node)
>> +		return -ENODEV;
>> +
>> +	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
>> +	if (!priv)
>> +		return -ENOMEM;
>> +
>> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +	mmio = devm_ioremap_resource(dev, res);
>> +	if (IS_ERR(mmio))
>> +		return PTR_ERR(mmio);
>> +
>> +	regmap = devm_regmap_init_mmio(dev, mmio, &stm32_dac_regmap_cfg);
>> +	if (IS_ERR(regmap))
>> +		return PTR_ERR(regmap);
>> +	priv->common.regmap = regmap;
>> +
>> +	priv->vref = devm_regulator_get(dev, "vref");
>> +	if (IS_ERR(priv->vref)) {
>> +		ret = PTR_ERR(priv->vref);
>> +		dev_err(dev, "vref get failed, %d\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	ret = regulator_enable(priv->vref);
>> +	if (ret < 0) {
>> +		dev_err(dev, "vref enable failed\n");
>> +		return ret;
>> +	}
>> +
>> +	ret = regulator_get_voltage(priv->vref);
>> +	if (ret < 0) {
>> +		dev_err(dev, "vref get voltage failed, %d\n", ret);
>> +		goto err_vref;
>> +	}
>> +	priv->common.vref_mv = ret / 1000;
>> +	dev_dbg(dev, "vref+=%dmV\n", priv->common.vref_mv);
>> +
>> +	priv->pclk = devm_clk_get(dev, "pclk");
>> +	if (IS_ERR(priv->pclk)) {
>> +		ret = PTR_ERR(priv->pclk);
>> +		dev_err(dev, "pclk get failed\n");
>> +		goto err_vref;
>> +	}
>> +
>> +	ret = clk_prepare_enable(priv->pclk);
>> +	if (ret < 0) {
>> +		dev_err(dev, "pclk enable failed\n");
>> +		goto err_vref;
>> +	}
>> +
>> +	priv->rst = devm_reset_control_get(dev, NULL);
>> +	if (!IS_ERR(priv->rst)) {
>> +		reset_control_assert(priv->rst);
>> +		udelay(2);
>> +		reset_control_deassert(priv->rst);
>> +	}
>> +
>> +	/* When clock speed is higher than 80MHz, set HFSEL */
>> +	priv->common.hfsel = (clk_get_rate(priv->pclk) > 80000000UL);
>> +	ret = regmap_update_bits(regmap, STM32_DAC_CR, STM32H7_DAC_CR_HFSEL,
>> +				 priv->common.hfsel ? STM32H7_DAC_CR_HFSEL : 0);
>> +	if (ret)
>> +		goto err_pclk;
>> +
>> +	platform_set_drvdata(pdev, &priv->common);
>> +
>> +	ret = of_platform_populate(pdev->dev.of_node, NULL, NULL, dev);
>> +	if (ret < 0) {
>> +		dev_err(dev, "failed to populate DT children\n");
>> +		goto err_pclk;
>> +	}
>> +
>> +	return 0;
>> +
>> +err_pclk:
>> +	clk_disable_unprepare(priv->pclk);
>> +err_vref:
>> +	regulator_disable(priv->vref);
>> +
>> +	return ret;
>> +}
>> +
>> +static int stm32_dac_remove(struct platform_device *pdev)
>> +{
>> +	struct stm32_dac_common *common = platform_get_drvdata(pdev);
>> +	struct stm32_dac_priv *priv = to_stm32_dac_priv(common);
>> +
>> +	of_platform_depopulate(&pdev->dev);
>> +	clk_disable_unprepare(priv->pclk);
>> +	regulator_disable(priv->vref);
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct of_device_id stm32_dac_of_match[] = {
>> +	{ .compatible = "st,stm32h7-dac-core", },
>> +	{},
>> +};
>> +MODULE_DEVICE_TABLE(of, stm32_dac_of_match);
>> +
>> +static struct platform_driver stm32_dac_driver = {
>> +	.probe = stm32_dac_probe,
>> +	.remove = stm32_dac_remove,
>> +	.driver = {
>> +		.name = "stm32-dac-core",
>> +		.of_match_table = stm32_dac_of_match,
>> +	},
>> +};
>> +module_platform_driver(stm32_dac_driver);
>> +
>> +MODULE_AUTHOR("Fabrice Gasnier <fabrice.gasnier@xxxxxx>");
>> +MODULE_DESCRIPTION("STMicroelectronics STM32 DAC core driver");
>> +MODULE_LICENSE("GPL v2");
>> +MODULE_ALIAS("platform:stm32-dac-core");
>> diff --git a/drivers/iio/dac/stm32-dac-core.h b/drivers/iio/dac/stm32-dac-core.h
>> new file mode 100644
>> index 0000000..daf0993
>> --- /dev/null
>> +++ b/drivers/iio/dac/stm32-dac-core.h
>> @@ -0,0 +1,51 @@
>> +/*
>> + * This file is part of STM32 DAC driver
>> + *
>> + * Copyright (C) 2017, STMicroelectronics - All Rights Reserved
>> + * Author: Fabrice Gasnier <fabrice.gasnier@xxxxxx>.
>> + *
>> + * License type: GPLv2
>> + *
>> + * This program is free software; you can redistribute it and/or modify it
>> + * under the terms of the GNU General Public License version 2 as published by
>> + * the Free Software Foundation.
>> + *
>> + * This program is distributed in the hope that it will be useful, but
>> + * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
>> + * or FITNESS FOR A PARTICULAR PURPOSE.
>> + * See the GNU General Public License for more details.
>> + *
>> + * You should have received a copy of the GNU General Public License along with
>> + * this program. If not, see <http://www.gnu.org/licenses/>.
>> + */
>> +
>> +#ifndef __STM32_DAC_CORE_H
>> +#define __STM32_DAC_CORE_H
>> +
>> +#include <linux/regmap.h>
>> +
>> +/* STM32 DAC registers */
>> +#define STM32_DAC_CR		0x00
>> +#define STM32_DAC_DHR12R1	0x08
>> +#define STM32_DAC_DHR12R2	0x14
>> +#define STM32_DAC_DOR1		0x2C
>> +#define STM32_DAC_DOR2		0x30
>> +
>> +/* STM32_DAC_CR bit fields */
>> +#define STM32_DAC_CR_EN1		BIT(0)
>> +#define STM32H7_DAC_CR_HFSEL		BIT(15)
>> +#define STM32_DAC_CR_EN2		BIT(16)
>> +
>> +/**
>> + * struct stm32_dac_common - stm32 DAC driver common data (for all instances)
>> + * @regmap: DAC registers shared via regmap
>> + * @vref_mv: reference voltage (mv)
>> + * @hfsel: high speed bus clock selected
>> + */
>> +struct stm32_dac_common {
>> +	struct regmap			*regmap;
>> +	int				vref_mv;
>> +	bool				hfsel;
>> +};
>> +
>> +#endif
>> diff --git a/drivers/iio/dac/stm32-dac.c b/drivers/iio/dac/stm32-dac.c
>> new file mode 100644
>> index 0000000..c0d993a
>> --- /dev/null
>> +++ b/drivers/iio/dac/stm32-dac.c
>> @@ -0,0 +1,350 @@
>> +/*
>> + * This file is part of STM32 DAC driver
>> + *
>> + * Copyright (C) 2017, STMicroelectronics - All Rights Reserved
>> + * Authors: Amelie Delaunay <amelie.delaunay@xxxxxx>
>> + *	    Fabrice Gasnier <fabrice.gasnier@xxxxxx>
>> + *
>> + * License type: GPLv2
>> + *
>> + * This program is free software; you can redistribute it and/or modify it
>> + * under the terms of the GNU General Public License version 2 as published by
>> + * the Free Software Foundation.
>> + *
>> + * This program is distributed in the hope that it will be useful, but
>> + * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
>> + * or FITNESS FOR A PARTICULAR PURPOSE.
>> + * See the GNU General Public License for more details.
>> + *
>> + * You should have received a copy of the GNU General Public License along with
>> + * this program. If not, see <http://www.gnu.org/licenses/>.
>> + */
>> +
>> +#include <linux/bitfield.h>
>> +#include <linux/delay.h>
>> +#include <linux/iio/iio.h>
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/platform_device.h>
>> +
>> +#include "stm32-dac-core.h"
>> +
>> +#define STM32_DAC_CHANNEL_1		1
>> +#define STM32_DAC_CHANNEL_2		2
>> +#define STM32_DAC_IS_CHAN_1(ch)		((ch) & STM32_DAC_CHANNEL_1)
>> +
>> +/**
>> + * struct stm32_dac - private data of DAC driver
>> + * @common:		reference to DAC common data
>> + */
>> +struct stm32_dac {
>> +	struct stm32_dac_common *common;
>> +};
>> +
>> +static int stm32_dac_is_enabled(struct iio_dev *indio_dev, int channel)
>> +{
>> +	struct stm32_dac *dac = iio_priv(indio_dev);
>> +	u32 en, val;
>> +	int ret;
>> +
>> +	ret = regmap_read(dac->common->regmap, STM32_DAC_CR, &val);
>> +	if (ret < 0)
>> +		return ret;
>> +	if (STM32_DAC_IS_CHAN_1(channel))
>> +		en = FIELD_GET(STM32_DAC_CR_EN1, val);
>> +	else
>> +		en = FIELD_GET(STM32_DAC_CR_EN2, val);
>> +
>> +	return !!en;
>> +}
>> +
>> +static int stm32_dac_enable(struct iio_dev *indio_dev, int channel)
>> +{
>> +	struct stm32_dac *dac = iio_priv(indio_dev);
>> +	u32 en = STM32_DAC_IS_CHAN_1(channel) ?
>> +		STM32_DAC_CR_EN1 : STM32_DAC_CR_EN2;
>> +	int ret;
>> +
>> +	ret = regmap_update_bits(dac->common->regmap, STM32_DAC_CR, en, en);
>> +	if (ret < 0) {
>> +		dev_err(&indio_dev->dev, "Enable failed\n");
>> +		return ret;
>> +	}
>> +
>> +	/*
>> +	 * When HFSEL is set, it is not allowed to write the DHRx register
>> +	 * during 8 clock cycles after the ENx bit is set. It is not allowed
>> +	 * to make software/hardware trigger during this period either.
>> +	 */
>> +	if (dac->common->hfsel)
>> +		udelay(1);
>> +
>> +	return 0;
>> +}
>> +
>> +static int stm32_dac_disable(struct iio_dev *indio_dev, int channel)
>> +{
>> +	struct stm32_dac *dac = iio_priv(indio_dev);
>> +	u32 en = STM32_DAC_IS_CHAN_1(channel) ?
>> +		STM32_DAC_CR_EN1 : STM32_DAC_CR_EN2;
>> +	int ret;
>> +
>> +	ret = regmap_update_bits(dac->common->regmap, STM32_DAC_CR, en, 0);
>> +	if (ret)
>> +		dev_err(&indio_dev->dev, "Disable failed\n");
>> +
>> +	return ret;
>> +}
>> +
>> +static int stm32_dac_get_value(struct stm32_dac *dac, int channel, int *val)
>> +{
>> +	int ret;
>> +
>> +	if (STM32_DAC_IS_CHAN_1(channel))
>> +		ret = regmap_read(dac->common->regmap, STM32_DAC_DOR1, val);
>> +	else
>> +		ret = regmap_read(dac->common->regmap, STM32_DAC_DOR2, val);
>> +
>> +	return ret ? ret : IIO_VAL_INT;
>> +}
>> +
>> +static int stm32_dac_set_value(struct stm32_dac *dac, int channel, int val)
>> +{
>> +	int ret;
>> +
>> +	if (STM32_DAC_IS_CHAN_1(channel))
>> +		ret = regmap_write(dac->common->regmap, STM32_DAC_DHR12R1, val);
>> +	else
>> +		ret = regmap_write(dac->common->regmap, STM32_DAC_DHR12R2, val);
>> +
>> +	return ret;
>> +}
>> +
>> +static int stm32_dac_read_raw(struct iio_dev *indio_dev,
>> +			      struct iio_chan_spec const *chan,
>> +			      int *val, int *val2, long mask)
>> +{
>> +	struct stm32_dac *dac = iio_priv(indio_dev);
>> +
>> +	switch (mask) {
>> +	case IIO_CHAN_INFO_RAW:
>> +		return stm32_dac_get_value(dac, chan->channel, val);
>> +	case IIO_CHAN_INFO_SCALE:
>> +		*val = dac->common->vref_mv;
>> +		*val2 = chan->scan_type.realbits;
>> +		return IIO_VAL_FRACTIONAL_LOG2;
>> +	default:
>> +		return -EINVAL;
>> +	}
>> +}
>> +
>> +static int stm32_dac_write_raw(struct iio_dev *indio_dev,
>> +			       struct iio_chan_spec const *chan,
>> +			       int val, int val2, long mask)
>> +{
>> +	struct stm32_dac *dac = iio_priv(indio_dev);
>> +
>> +	switch (mask) {
>> +	case IIO_CHAN_INFO_RAW:
>> +		return stm32_dac_set_value(dac, chan->channel, val);
>> +	default:
>> +		return -EINVAL;
>> +	}
>> +}
>> +
>> +static int stm32_dac_debugfs_reg_access(struct iio_dev *indio_dev,
>> +					unsigned reg, unsigned writeval,
>> +					unsigned *readval)
>> +{
>> +	struct stm32_dac *dac = iio_priv(indio_dev);
>> +
>> +	if (!readval)
>> +		return regmap_write(dac->common->regmap, reg, writeval);
>> +	else
>> +		return regmap_read(dac->common->regmap, reg, readval);
>> +}
>> +
>> +static const struct iio_info stm32_dac_iio_info = {
>> +	.read_raw = stm32_dac_read_raw,
>> +	.write_raw = stm32_dac_write_raw,
>> +	.debugfs_reg_access = stm32_dac_debugfs_reg_access,
>> +	.driver_module = THIS_MODULE,
>> +};
>> +
>> +static const char * const stm32_dac_powerdown_modes[] = {
>> +	"Hi-Z",
>> +	"enable",
> I wouldn't expect to see enable in here, that is handled by the power down
> attribute.
> 
> Hi-Z is the currently defined threestate I think?
> 
> Documenation/ABI/testing/sysfs-bus-iio

Yes, documentation states: "three_state: left floating".
Thanks for pointing that out.

> 
> Fine to propose additions to this but they need documenting in that general
> file.
>> +};
>> +
>> +static int stm32_dac_get_powerdown_mode(struct iio_dev *indio_dev,
>> +					const struct iio_chan_spec *chan)
>> +{
>> +	return stm32_dac_is_enabled(indio_dev, chan->channel);
>> +}
>> +
>> +static int stm32_dac_set_powerdown_mode(struct iio_dev *indio_dev,
>> +					const struct iio_chan_spec *chan,
>> +					unsigned int type)
>> +{
>> +	if (type)
>> +		return stm32_dac_enable(indio_dev, chan->channel);
>> +	else
>> +		return stm32_dac_disable(indio_dev, chan->channel);
>> +}
>> +
>> +static ssize_t stm32_dac_read_powerdown(struct iio_dev *indio_dev,
>> +					uintptr_t private,
>> +					const struct iio_chan_spec *chan,
>> +					char *buf)
>> +{
>> +	int ret = stm32_dac_is_enabled(indio_dev, chan->channel);
>> +
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	return sprintf(buf, "%d\n", ret);
>> +}
>> +
>> +static ssize_t stm32_dac_write_powerdown(struct iio_dev *indio_dev,
>> +					 uintptr_t private,
>> +					 const struct iio_chan_spec *chan,
>> +					 const char *buf, size_t len)
>> +{
>> +	unsigned int en;
>> +	int ret;
>> +
>> +	ret = kstrtouint(buf, 0, &en);
> strtobool perhaps?

Done in v3. I also reworked a little all around powerdown mode.

Thanks,
Fabrice

>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = stm32_dac_set_powerdown_mode(indio_dev, chan, en);
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	return len;
>> +}
>> +
>> +static const struct iio_enum stm32_dac_powerdown_mode_en = {
>> +	.items = stm32_dac_powerdown_modes,
>> +	.num_items = ARRAY_SIZE(stm32_dac_powerdown_modes),
>> +	.get = stm32_dac_get_powerdown_mode,
>> +	.set = stm32_dac_set_powerdown_mode,
>> +};
>> +
>> +static const struct iio_chan_spec_ext_info stm32_dac_ext_info[] = {
>> +	{
>> +		.name = "powerdown",
>> +		.read = stm32_dac_read_powerdown,
>> +		.write = stm32_dac_write_powerdown,
>> +		.shared = IIO_SEPARATE,
>> +	},
>> +	IIO_ENUM("powerdown_mode", IIO_SEPARATE, &stm32_dac_powerdown_mode_en),
>> +	IIO_ENUM_AVAILABLE("powerdown_mode", &stm32_dac_powerdown_mode_en),
>> +	{},
>> +};
>> +
>> +#define STM32_DAC_CHANNEL(chan, name) {			\
>> +	.type = IIO_VOLTAGE,				\
>> +	.indexed = 1,					\
>> +	.output = 1,					\
>> +	.channel = chan,				\
>> +	.info_mask_separate =				\
>> +		BIT(IIO_CHAN_INFO_RAW) |		\
>> +		BIT(IIO_CHAN_INFO_SCALE),		\
>> +	/* scan_index is always 0 as num_channels is 1 */ \
>> +	.scan_type = {					\
>> +		.sign = 'u',				\
>> +		.realbits = 12,				\
>> +		.storagebits = 16,			\
>> +	},						\
>> +	.datasheet_name = name,				\
>> +	.ext_info = stm32_dac_ext_info			\
>> +}
>> +
>> +static const struct iio_chan_spec stm32_dac_channels[] = {
>> +	STM32_DAC_CHANNEL(STM32_DAC_CHANNEL_1, "out1"),
>> +	STM32_DAC_CHANNEL(STM32_DAC_CHANNEL_2, "out2"),
>> +};
>> +
>> +static int stm32_dac_chan_of_init(struct iio_dev *indio_dev)
>> +{
>> +	struct device_node *np = indio_dev->dev.of_node;
>> +	unsigned int i;
>> +	u32 channel;
>> +	int ret;
>> +
>> +	ret = of_property_read_u32(np, "reg", &channel);
>> +	if (ret) {
>> +		dev_err(&indio_dev->dev, "Failed to read reg property\n");
>> +		return ret;
>> +	}
>> +
>> +	for (i = 0; i < ARRAY_SIZE(stm32_dac_channels); i++) {
>> +		if (stm32_dac_channels[i].channel == channel)
>> +			break;
>> +	}
>> +	if (i >= ARRAY_SIZE(stm32_dac_channels)) {
>> +		dev_err(&indio_dev->dev, "Invalid st,dac-channel\n");
>> +		return -EINVAL;
>> +	}
>> +
>> +	indio_dev->channels = &stm32_dac_channels[i];
>> +	/*
>> +	 * Expose only one channel here, as they can be used independently,
>> +	 * with separate trigger. Then separate IIO devices are instantiated
>> +	 * to manage this.
>> +	 */
>> +	indio_dev->num_channels = 1;
>> +
>> +	return 0;
>> +};
>> +
>> +static int stm32_dac_probe(struct platform_device *pdev)
>> +{
>> +	struct device_node *np = pdev->dev.of_node;
>> +	struct iio_dev *indio_dev;
>> +	struct stm32_dac *dac;
>> +	int ret;
>> +
>> +	if (!np)
>> +		return -ENODEV;
>> +
>> +	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*dac));
>> +	if (!indio_dev)
>> +		return -ENOMEM;
>> +	platform_set_drvdata(pdev, indio_dev);
>> +
>> +	dac = iio_priv(indio_dev);
>> +	dac->common = dev_get_drvdata(pdev->dev.parent);
>> +	indio_dev->name = dev_name(&pdev->dev);
>> +	indio_dev->dev.parent = &pdev->dev;
>> +	indio_dev->dev.of_node = pdev->dev.of_node;
>> +	indio_dev->info = &stm32_dac_iio_info;
>> +	indio_dev->modes = INDIO_DIRECT_MODE;
>> +
>> +	ret = stm32_dac_chan_of_init(indio_dev);
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	return devm_iio_device_register(&pdev->dev, indio_dev);
>> +}
>> +
>> +static const struct of_device_id stm32_dac_of_match[] = {
>> +	{ .compatible = "st,stm32-dac", },
>> +	{},
>> +};
>> +MODULE_DEVICE_TABLE(of, stm32_dac_of_match);
>> +
>> +static struct platform_driver stm32_dac_driver = {
>> +	.probe = stm32_dac_probe,
>> +	.driver = {
>> +		.name = "stm32-dac",
>> +		.of_match_table = stm32_dac_of_match,
>> +	},
>> +};
>> +module_platform_driver(stm32_dac_driver);
>> +
>> +MODULE_ALIAS("platform:stm32-dac");
>> +MODULE_AUTHOR("Amelie Delaunay <amelie.delaunay@xxxxxx>");
>> +MODULE_DESCRIPTION("STMicroelectronics STM32 DAC driver");
>> +MODULE_LICENSE("GPL v2");
>>
>