Message-ID: <20200215163239.1b55e999@archlinux>
Date:   Sat, 15 Feb 2020 16:32:39 +0000
From:   Jonathan Cameron <jic23@...nel.org>
To:     Alexandru Tachici <alexandru.tachici@...log.com>
Cc:     <linux-iio@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Mircea Caprioru <mircea.caprioru@...log.com>
Subject: Re: [PATCH v3 1/2] iio: dac: ad5770r: Add AD5770R support

On Thu, 13 Feb 2020 13:39:15 +0200
Alexandru Tachici <alexandru.tachici@...log.com> wrote:

> The AD5770R is a 6-channel, 14-bit resolution, low noise, programmable
> current output digital-to-analog converter (DAC) for photonics control
> applications.
> 
> It contains five 14-bit resolution current sourcing DAC channels and one
> 14-bit resolution current sourcing/sinking DAC channel.
> 
> Signed-off-by: Mircea Caprioru <mircea.caprioru@...log.com>
> Signed-off-by: Alexandru Tachici <alexandru.tachici@...log.com>
A few last minute bits inline.  I wonder if we should perhaps allow the binding
to not specify all the channels and leave any unspecified ones powered down.

For a multiple output DAC like this I expect there are some designs where
not all the outputs are wired to anything.

Jonathan

> ---
>  drivers/iio/dac/Kconfig   |  10 +
>  drivers/iio/dac/Makefile  |   1 +
>  drivers/iio/dac/ad5770r.c | 695 ++++++++++++++++++++++++++++++++++++++
>  3 files changed, 706 insertions(+)
>  create mode 100644 drivers/iio/dac/ad5770r.c
> 
> diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
> index 979070196da9..c74f2151ee42 100644
> --- a/drivers/iio/dac/Kconfig
> +++ b/drivers/iio/dac/Kconfig
> @@ -208,6 +208,16 @@ config AD5764
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called ad5764.
>  
> +config AD5770R
> +	tristate "Analog Devices AD5770R IDAC driver"
> +	depends on SPI_MASTER
> +	help
> +	  Say yes here to build support for Analog Devices AD5770R Digital to
> +	  Analog Converter.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called ad5770r.
> +
>  config AD5791
>  	tristate "Analog Devices AD5760/AD5780/AD5781/AD5790/AD5791 DAC SPI driver"
>  	depends on SPI
> diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile
> index 1369fa1d2f0e..2fc481167724 100644
> --- a/drivers/iio/dac/Makefile
> +++ b/drivers/iio/dac/Makefile
> @@ -19,6 +19,7 @@ obj-$(CONFIG_AD5755) += ad5755.o
>  obj-$(CONFIG_AD5755) += ad5758.o
>  obj-$(CONFIG_AD5761) += ad5761.o
>  obj-$(CONFIG_AD5764) += ad5764.o
> +obj-$(CONFIG_AD5770R) += ad5770r.o
>  obj-$(CONFIG_AD5791) += ad5791.o
>  obj-$(CONFIG_AD5686) += ad5686.o
>  obj-$(CONFIG_AD5686_SPI) += ad5686-spi.o
> diff --git a/drivers/iio/dac/ad5770r.c b/drivers/iio/dac/ad5770r.c
> new file mode 100644
> index 000000000000..7765310b074a
> --- /dev/null
> +++ b/drivers/iio/dac/ad5770r.c
> @@ -0,0 +1,695 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * AD5770R Digital to analog converters driver
> + *
> + * Copyright 2018 Analog Devices Inc.
> + */
> +
> +#include <linux/bits.h>
> +#include <linux/delay.h>
> +#include <linux/device.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/iio/common/adi_spi_regs.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/property.h>
> +#include <linux/regmap.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/spi/spi.h>
> +
> +#define ADI_SPI_IF_CONFIG_A		0x00
> +#define ADI_SPI_IF_CONFIG_B		0x01
> +#define ADI_SPI_IF_DEVICE_CONFIG	0x02
> +#define ADI_SPI_IF_CHIP_TYPE		0x03
> +#define ADI_SPI_IF_PRODUCT_ID_L		0x04
> +#define ADI_SPI_IF_PRODUCT_ID_H		0x05
> +#define ADI_SPI_IF_CHIP_GRADE		0x06
> +#define ADI_SPI_IF_SCRACTH_PAD		0x0A
> +#define ADI_SPI_IF_SPI_REVISION		0x0B
> +#define ADI_SPI_IF_SPI_VENDOR_L		0x0C
> +#define ADI_SPI_IF_SPI_VENDOR_H		0x0D
> +#define ADI_SPI_IF_SPI_STREAM_MODE	0x0E
> +#define ADI_SPI_IF_CONFIG_C		0x10
> +#define ADI_SPI_IF_STATUS_A		0x11
> +
> +/* ADI_SPI_IF_CONFIG_A */
> +#define ADI_SPI_IF_SW_RESET_MSK		(BIT(0) | BIT(7))
> +#define ADI_SPI_IF_SW_RESET_SEL(x)	((x) & ADI_SPI_IF_SW_RESET_MSK)
> +#define ADI_SPI_IF_ADDR_ASC_MSK		(BIT(2) | BIT(5))
> +#define ADI_SPI_IF_ADDR_ASC_SEL(x)	(((x) << 2) & ADI_SPI_IF_ADDR_ASC_MSK)
> +
> +/* ADI_SPI_IF_CONFIG_B */
> +#define ADI_SPI_IF_SINGLE_INS_MSK	BIT(7)
> +#define ADI_SPI_IF_SINGLE_INS_SEL(x)	FIELD_PREP(ADI_SPI_IF_SINGLE_INS_MSK, x)
> +#define ADI_SPI_IF_SHORT_INS_MSK	BIT(7)
> +#define ADI_SPI_IF_SHORT_INS_SEL(x)	FIELD_PREP(ADI_SPI_IF_SINGLE_INS_MSK, x)
> +
> +/* ADI_SPI_IF_CONFIG_C */
> +#define ADI_SPI_IF_STRICT_REG_MSK	BIT(5)
> +#define ADI_SPI_IF_STRICT_REG_GET(x)	FIELD_GET(ADI_SPI_IF_STRICT_REG_MSK, x)
> +
> +/* AD5770R configuration registers */
> +#define AD5770R_CHANNEL_CONFIG		0x14
> +#define AD5770R_OUTPUT_RANGE(ch)	(0x15 + (ch))
> +#define AD5770R_FILTER_RESISTOR(ch)	(0x1D + (ch))
> +#define AD5770R_REFERENCE		0x1B
> +#define AD5770R_DAC_LSB(ch)		(0x26 + 2 * (ch))
> +#define AD5770R_DAC_MSB(ch)		(0x27 + 2 * (ch))
> +#define AD5770R_CH_SELECT		0x34
> +#define AD5770R_CH_ENABLE		0x44
> +
> +/* AD5770R_CHANNEL_CONFIG */
> +#define AD5770R_CFG_CH0_SINK_EN(x)		(((x) & 0x1) << 7)
> +#define AD5770R_CFG_SHUTDOWN_B(x, ch)		(((x) & 0x1) << (ch))
> +
> +/* AD5770R_OUTPUT_RANGE */
> +#define AD5770R_RANGE_OUTPUT_SCALING(x)		(((x) & 0x3F) << 2)

GENMASK preferred when defining the various contiguous masks.

> +#define AD5770R_RANGE_MODE(x)			((x) & 0x03)
> +
> +/* AD5770R_REFERENCE */
> +#define AD5770R_REF_RESISTOR_SEL(x)		(((x) & 0x1) << 2)
> +#define AD5770R_REF_SEL(x)			(((x) & 0x3) << 0)
> +
> +/* AD5770R_CH_ENABLE */
> +#define AD5770R_CH_SET(x, channel)		(((x) & 0x1) << (channel))

ch used elsehwere.  Maybe change for consistency?

> +
> +#define AD5770R_MAX_CHANNELS	6
> +#define AD5770R_MAX_CH_MODES	14
> +#define AD5770R_LOW_VREF_mV	1250
> +#define AD5770R_HIGH_VREF_mV	2500
> +
> +enum ad5770r_ch0_modes {
> +	AD5770R_CH0_0_300 = 0,
> +	AD5770R_CH0_NEG_60_0,
> +	AD5770R_CH0_NEG_60_300
> +};
> +
> +enum ad5770r_ch1_modes {
> +	AD5770R_CH1_0_140_LOW_HEAD = 1,
> +	AD5770R_CH1_0_140_LOW_NOISE,
> +	AD5770R_CH1_0_250
> +};
> +
> +enum ad5770r_ch2_5_modes {
> +	AD5770R_CH_LOW_RANGE = 0,
> +	AD5770R_CH_HIGH_RANGE
> +};
> +
> +enum ad5770r_ref_v {
> +	AD5770R_EXT_2_5_V = 0,
> +	AD5770R_INT_1_25_V_OUT_ON,
> +	AD5770R_EXT_1_25_V,
> +	AD5770R_INT_1_25_V_OUT_OFF
> +};
> +
> +enum ad5770r_output_filter_resistor {
> +	AD5770R_FILTER_60_OHM = 0x0,
> +	AD5770R_FILTER_5_6_KOHM = 0x5,
> +	AD5770R_FILTER_11_2_KOHM,
> +	AD5770R_FILTER_22_2_KOHM,
> +	AD5770R_FILTER_44_4_KOHM,
> +	AD5770R_FILTER_104_KOHM,
> +};
> +
> +struct ad5770r_out_range {
> +	u8	out_scale;
> +	u8	out_range_mode;
> +};
> +
> +/**
> + * struct ad5770R_state - driver instance specific data
> + * @spi:		spi_device
> + * @regmap:		regmap
> + * @vref_reg:		fixed regulator for reference configuration
> + * @gpio_reset:		gpio descriptor
> + * @output_mode:		array contains channels output ranges
> + * @vref:		reference value
> + * @ch_pwr_down:		powerdown flags
> + * @internal_ref:	internal reference flag
> + * @external_res:	external 2.5k resistor flag
> + */
> +struct ad5770r_state {
> +	struct spi_device		*spi;
> +	struct regmap			*regmap;
> +	struct regulator		*vref_reg;
> +	struct gpio_desc		*gpio_reset;
> +	struct ad5770r_out_range	output_mode[AD5770R_MAX_CHANNELS];
> +	int				vref;
> +	bool				ch_pwr_down[AD5770R_MAX_CHANNELS];
> +	bool				internal_ref;
> +	bool				external_res;
> +};
> +
> +static const struct regmap_config ad5770r_spi_regmap_config = {
> +	.reg_bits = 8,
> +	.val_bits = 8,
> +	.read_flag_mask = BIT(7),
> +};
> +
> +struct ad5770r_output_modes {
> +	unsigned int ch;
> +	u8 mode;
> +	int min;
> +	int max;
> +};
> +
> +static struct ad5770r_output_modes ad5770r_rng_tbl[] = {
> +	{ 0, AD5770R_CH0_0_300, 0, 300 },
> +	{ 0, AD5770R_CH0_NEG_60_0, -60, 0 },
> +	{ 0, AD5770R_CH0_NEG_60_300, -60, 300 },
> +	{ 1, AD5770R_CH1_0_140_LOW_HEAD, 0, 140 },
> +	{ 1, AD5770R_CH1_0_140_LOW_NOISE, 0, 140 },
> +	{ 1, AD5770R_CH1_0_250, 0, 250 },
> +	{ 2, AD5770R_CH_LOW_RANGE, 0, 55 },
> +	{ 2, AD5770R_CH_HIGH_RANGE, 0, 150 },
> +	{ 3, AD5770R_CH_LOW_RANGE, 0, 45 },
> +	{ 3, AD5770R_CH_HIGH_RANGE, 0, 100 },
> +	{ 4, AD5770R_CH_LOW_RANGE, 0, 45 },
> +	{ 4, AD5770R_CH_HIGH_RANGE, 0, 100 },
> +	{ 5, AD5770R_CH_LOW_RANGE, 0, 45 },
> +	{ 5, AD5770R_CH_HIGH_RANGE, 0, 100 },
> +};
> +
> +static const unsigned int ad5770r_filter_freqs[] = {
> +	153, 357, 715, 1400, 2800, 262000,
> +};
> +
> +static const unsigned int ad5770r_filter_reg_vals[] = {
> +	AD5770R_FILTER_104_KOHM,
> +	AD5770R_FILTER_44_4_KOHM,
> +	AD5770R_FILTER_22_2_KOHM,
> +	AD5770R_FILTER_11_2_KOHM,
> +	AD5770R_FILTER_5_6_KOHM,
> +	AD5770R_FILTER_60_OHM
> +};
> +
> +static int ad5770r_set_output_mode(struct ad5770r_state *st,
> +				   const struct ad5770r_out_range *out_mode,
> +				   int channel)
> +{
> +	unsigned int regval;
> +
> +	regval = AD5770R_RANGE_OUTPUT_SCALING(out_mode->out_scale) |
> +		 AD5770R_RANGE_MODE(out_mode->out_range_mode);
> +
> +	return regmap_write(st->regmap,
> +			    AD5770R_OUTPUT_RANGE(channel), regval);
> +}
> +
> +static int ad5770r_set_reference(struct ad5770r_state *st)
> +{
> +	unsigned int regval;
> +
> +	regval = AD5770R_REF_RESISTOR_SEL(st->external_res);
> +
> +	if (st->internal_ref) {
> +		regval |= AD5770R_REF_SEL(AD5770R_INT_1_25_V_OUT_OFF);
> +	} else {
> +		switch (st->vref) {
> +		case AD5770R_LOW_VREF_mV:
> +			regval |= AD5770R_REF_SEL(AD5770R_EXT_1_25_V);
> +			break;
> +		case AD5770R_HIGH_VREF_mV:
> +			regval |= AD5770R_REF_SEL(AD5770R_EXT_2_5_V);
> +			break;
> +		default:
> +			regval = AD5770R_REF_SEL(AD5770R_INT_1_25_V_OUT_OFF);
> +			break;
> +		}
> +	}
> +
> +	return regmap_write(st->regmap, AD5770R_REFERENCE, regval);
> +}
> +
> +static int ad5770r_soft_reset(struct ad5770r_state *st)
> +{
> +	return regmap_write(st->regmap, ADI_SPI_IF_CONFIG_A,
> +			    ADI_SPI_IF_SW_RESET_SEL(1));
> +}
> +
> +static int ad5770r_reset(struct ad5770r_state *st)
> +{
> +	/* Perform software reset if no GPIO provided */
> +	if (!st->gpio_reset)
> +		return ad5770r_soft_reset(st);
> +
> +	gpiod_set_value_cansleep(st->gpio_reset, 0);
> +	usleep_range(10, 20);
> +	gpiod_set_value_cansleep(st->gpio_reset, 1);
> +
> +	/* data must not be written during reset timeframe */
> +	usleep_range(100, 200);
> +
> +	return 0;
> +}
> +
> +static int ad5770r_get_range(struct ad5770r_state *st,
> +			     int ch, int *min, int *max)
> +{
> +	int i;
> +	u8 tbl_ch, tbl_mode, out_range;
> +
> +	out_range = st->output_mode[ch].out_range_mode;
> +
> +	for (i = 0; i < AD5770R_MAX_CH_MODES; i++) {
> +		tbl_ch = ad5770r_rng_tbl[i].ch;
> +		tbl_mode = ad5770r_rng_tbl[i].mode;
> +		if (tbl_ch == ch && tbl_mode == out_range) {
> +			*min = ad5770r_rng_tbl[i].min;
> +			*max = ad5770r_rng_tbl[i].max;
> +			return 0;
> +		}
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static int ad5770r_get_filter_freq(struct iio_dev *indio_dev,
> +				   const struct iio_chan_spec *chan, int *freq)
> +{
> +	struct ad5770r_state *st = iio_priv(indio_dev);
> +	int ret;
> +	unsigned int regval, i;
> +
> +	ret = regmap_read(st->regmap,
> +			  AD5770R_FILTER_RESISTOR(chan->channel), &regval);
> +	if (ret < 0)
> +		return ret;
> +
> +	for (i = 0; i < ARRAY_SIZE(ad5770r_filter_reg_vals); i++)
> +		if (regval == ad5770r_filter_reg_vals[i])
> +			break;
> +	if (i == ARRAY_SIZE(ad5770r_filter_reg_vals))
> +		return -EINVAL;
> +
> +	*freq = ad5770r_filter_freqs[i];
> +
> +	return IIO_VAL_INT;
> +}
> +
> +static int ad5770r_set_filter_freq(struct iio_dev *indio_dev,
> +				   const struct iio_chan_spec *chan,
> +				   unsigned int freq)
> +{
> +	struct ad5770r_state *st = iio_priv(indio_dev);
> +	unsigned int regval, i;
> +
> +	for (i = 0; i < ARRAY_SIZE(ad5770r_filter_freqs); i++)
> +		if (ad5770r_filter_freqs[i] >= freq)
> +			break;
> +	if (i == ARRAY_SIZE(ad5770r_filter_freqs))
> +		return -EINVAL;
> +
> +	regval = ad5770r_filter_reg_vals[i];
> +
> +	return regmap_write(st->regmap, AD5770R_FILTER_RESISTOR(chan->channel),
> +			    regval);
> +}
> +
> +static int ad5770r_read_raw(struct iio_dev *indio_dev,
> +			    struct iio_chan_spec const *chan,
> +			    int *val, int *val2, long info)
> +{
> +	struct ad5770r_state *st = iio_priv(indio_dev);
> +	int max, min, ret;
> +	__le16 buf16;
> +
> +	switch (info) {
> +	case IIO_CHAN_INFO_RAW:
> +		ret = regmap_bulk_read(st->regmap,
> +				       chan->address,
> +				       &buf16, 2);

I'm fairly sure regmap spi needs DMA safe buffers for bulk read / write.
As such you can't use a variable on the stack safely.

> +		if (ret)
> +			return 0;
> +		*val = le16_to_cpu(buf16) >> 2;
> +		return IIO_VAL_INT;
> +	case IIO_CHAN_INFO_SCALE:
> +		ret = ad5770r_get_range(st, chan->channel, &min, &max);
> +		if (ret < 0)
> +			return ret;
> +		*val = max - min;
> +		/* There is no sign bit. (negative current is mapped from 0)
> +		 * (sourced/sinked) current = raw * scale + offset
> +		 * where offset in case of CH0 can be negative.
> +		 */
> +		*val2 = 14;
> +		return IIO_VAL_FRACTIONAL_LOG2;
> +	case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
> +		return ad5770r_get_filter_freq(indio_dev, chan, val);
> +	case IIO_CHAN_INFO_OFFSET:
> +		ret = ad5770r_get_range(st, chan->channel, &min, &max);
> +		if (ret < 0)
> +			return ret;
> +		*val = min;
> +		return IIO_VAL_INT;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int ad5770r_write_raw(struct iio_dev *indio_dev,
> +			     struct iio_chan_spec const *chan,
> +			     int val, int val2, long info)
> +{
> +	struct ad5770r_state *st = iio_priv(indio_dev);
> +	u8 buf[2];
> +
> +	switch (info) {
> +	case IIO_CHAN_INFO_RAW:
> +		buf[0] = ((u16)val >> 6);
> +		buf[1] = (val & 0x3F) << 2;
> +		return regmap_bulk_write(st->regmap, chan->address,
> +					 buf, ARRAY_SIZE(buf));
> +	case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
> +		return ad5770r_set_filter_freq(indio_dev, chan, val);
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int ad5770r_read_freq_avail(struct iio_dev *indio_dev,
> +				   struct iio_chan_spec const *chan,
> +				   const int **vals, int *type, int *length,
> +				   long mask)
> +{
> +	switch (mask) {
> +	case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
> +		*type = IIO_VAL_INT;
> +		*vals = ad5770r_filter_freqs;
> +		*length = ARRAY_SIZE(ad5770r_filter_freqs);
> +		return IIO_AVAIL_LIST;
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static int ad5770r_reg_access(struct iio_dev *indio_dev,
> +			      unsigned int reg,
> +			      unsigned int writeval,
> +			      unsigned int *readval)
> +{
> +	struct ad5770r_state *st = iio_priv(indio_dev);
> +
> +	if (readval)
> +		return regmap_read(st->regmap, reg, readval);
> +	else
> +		return regmap_write(st->regmap, reg, writeval);
> +}
> +
> +static const struct iio_info ad5770r_info = {
> +	.read_raw = ad5770r_read_raw,
> +	.write_raw = ad5770r_write_raw,
> +	.read_avail = ad5770r_read_freq_avail,
> +	.debugfs_reg_access = &ad5770r_reg_access,
> +};
> +
> +static int ad5770r_store_output_range(struct ad5770r_state *st,
> +				      int min, int max, int index)
> +{
> +	int i;
> +
> +	for (i = 0; i < AD5770R_MAX_CH_MODES; i++) {
> +		if (ad5770r_rng_tbl[i].ch != index)
> +			continue;
> +		if (ad5770r_rng_tbl[i].min != min ||
> +		    ad5770r_rng_tbl[i].max != max)
> +			continue;
> +		st->output_mode[index].out_range_mode = ad5770r_rng_tbl[i].mode;
> +
> +		return 0;
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static ssize_t ad5770r_read_dac_powerdown(struct iio_dev *indio_dev,
> +					  uintptr_t private,
> +					  const struct iio_chan_spec *chan,
> +					  char *buf)
> +{
> +	struct ad5770r_state *st = iio_priv(indio_dev);
> +
> +	return sprintf(buf, "%d\n", st->ch_pwr_down[chan->channel]);
> +}
> +
> +static ssize_t ad5770r_write_dac_powerdown(struct iio_dev *indio_dev,
> +					   uintptr_t private,
> +					   const struct iio_chan_spec *chan,
> +					   const char *buf, size_t len)
> +{
> +	struct ad5770r_state *st = iio_priv(indio_dev);
> +	unsigned int regval;
> +	unsigned int mask;
> +	bool readin;
> +	int ret;
> +
> +	ret = kstrtobool(buf, &readin);
> +	if (ret)
> +		return ret;
> +
> +	readin = !readin;
> +
> +	regval = AD5770R_CFG_SHUTDOWN_B(readin, chan->channel);
> +	if (chan->channel == 0 &&
> +	    st->output_mode[0].out_range_mode > AD5770R_CH0_0_300) {
> +		regval |= AD5770R_CFG_CH0_SINK_EN(readin);
> +		mask = BIT(chan->channel) + BIT(7);
> +	} else {
> +		mask = BIT(chan->channel);
> +	}
> +	ret = regmap_update_bits(st->regmap, AD5770R_CHANNEL_CONFIG, mask,
> +				 regval);
> +	if (ret)
> +		return ret;
> +
> +	regval = AD5770R_CH_SET(readin, chan->channel);
> +	ret = regmap_update_bits(st->regmap, AD5770R_CH_ENABLE,
> +				 BIT(chan->channel), regval);
> +	if (ret)
> +		return ret;
> +
> +	st->ch_pwr_down[chan->channel] = !readin;
> +
> +	return len;
> +}
> +
> +static const struct iio_chan_spec_ext_info ad5770r_ext_info[] = {
> +	{
> +		.name = "powerdown",
> +		.read = ad5770r_read_dac_powerdown,
> +		.write = ad5770r_write_dac_powerdown,
> +		.shared = IIO_SEPARATE,
> +	},
> +	{ }
> +};
> +
> +#define AD5770R_IDAC_CHANNEL(index, reg) {				\
> +	.type = IIO_CURRENT,						\
> +	.address = reg,							\
> +	.indexed = 1,							\
> +	.channel = index,						\
> +	.output = 1,							\
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |			\
> +		BIT(IIO_CHAN_INFO_SCALE) |				\
> +		BIT(IIO_CHAN_INFO_OFFSET) |				\
> +		BIT(IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY),	\
> +	.info_mask_shared_by_type_available =				\
> +		BIT(IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY),	\
> +	.ext_info = ad5770r_ext_info,					\
> +}
> +
> +static const struct iio_chan_spec ad5770r_channels[] = {
> +	AD5770R_IDAC_CHANNEL(0, AD5770R_DAC_MSB(0)),
> +	AD5770R_IDAC_CHANNEL(1, AD5770R_DAC_MSB(1)),
> +	AD5770R_IDAC_CHANNEL(2, AD5770R_DAC_MSB(2)),
> +	AD5770R_IDAC_CHANNEL(3, AD5770R_DAC_MSB(3)),
> +	AD5770R_IDAC_CHANNEL(4, AD5770R_DAC_MSB(4)),
> +	AD5770R_IDAC_CHANNEL(5, AD5770R_DAC_MSB(5)),
> +};
> +
> +static int ad5770r_channel_config(struct ad5770r_state *st)
> +{
> +	int ret, tmp[2], min, max;
> +	unsigned int num;
> +	struct fwnode_handle *child;
> +
> +	num = device_get_child_node_count(&st->spi->dev);
> +	if (num != AD5770R_MAX_CHANNELS)
> +		return -EINVAL;
> +
> +	device_for_each_child_node(&st->spi->dev, child) {
> +		ret = fwnode_property_read_u32(child, "num", &num);
> +		if (ret)
> +			return ret;
> +		if (num > AD5770R_MAX_CHANNELS)
> +			return -EINVAL;
> +
> +		ret = fwnode_property_read_u32_array(child,
> +						     "adi,range-microamp",
> +						     tmp, 2);
> +		if (ret)
> +			return ret;
> +
> +		min = tmp[0] / 1000;
> +		max = tmp[1] / 1000;
> +		ret = ad5770r_store_output_range(st, min, max, num);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	return ret;
> +}
> +
> +static int ad5770r_init(struct ad5770r_state *st)
> +{
> +	int ret, i;
> +
> +	st->gpio_reset = devm_gpiod_get_optional(&st->spi->dev, "reset",
> +						 GPIOD_OUT_HIGH);
> +	if (IS_ERR(st->gpio_reset))
> +		return PTR_ERR(st->gpio_reset);
> +
> +	/* Perform a reset */
> +	ret = ad5770r_reset(st);
> +	if (ret)
> +		return ret;
> +
> +	/* Set output range */
> +	ret = ad5770r_channel_config(st);
> +	if (ret)
> +		return ret;
> +
> +	for (i = 0; i < AD5770R_MAX_CHANNELS; i++) {
> +		ret = ad5770r_set_output_mode(st,  &st->output_mode[i], i);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	st->external_res = fwnode_property_read_bool(st->spi->dev.fwnode,
> +						     "adi,external-resistor");
> +
> +	ret = ad5770r_set_reference(st);
> +	if (ret)
> +		return ret;
> +
> +	/* Set outputs off */
> +	ret = regmap_write(st->regmap, AD5770R_CHANNEL_CONFIG, 0x00);
> +	if (ret)
> +		return ret;
> +
> +	ret = regmap_write(st->regmap, AD5770R_CH_ENABLE, 0x00);
> +	if (ret)
> +		return ret;
> +
> +	for (i = 0; i < AD5770R_MAX_CHANNELS; i++)
> +		st->ch_pwr_down[i] = true;
> +
> +	return ret;
> +}
> +
> +static void ad5770r_disable_regulator(void *data)
> +{
> +	struct spi_device *spi = (struct spi_device *)data;

No need to explicitly cast a void * to anything.
	struct spi_device *spi = data;
is always fine under the c specification.
I'd skip it though and do..

struct iio_dev *indio_dev = spi_get_drvdata(data);
directly.

> +	struct iio_dev *indio_dev = spi_get_drvdata(spi);
> +	struct ad5770r_state *st = iio_priv(indio_dev);
> +
> +	if (st->vref_reg)

With change suggested below, this will only be called
if st->vref_reg != NULL so no need for the check.

> +		regulator_disable(st->vref_reg);
> +}
> +
> +static int ad5770r_probe(struct spi_device *spi)
> +{
> +	struct ad5770r_state *st;
> +	struct iio_dev *indio_dev;
> +	struct regmap *regmap;
> +	int ret;
> +
> +	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	st = iio_priv(indio_dev);
> +	spi_set_drvdata(spi, indio_dev);
> +
> +	st->spi = spi;
> +
> +	regmap = devm_regmap_init_spi(spi, &ad5770r_spi_regmap_config);
> +	if (IS_ERR(regmap)) {
> +		dev_err(&spi->dev, "Error initializing spi regmap: %ld\n",
> +			PTR_ERR(regmap));
> +		return PTR_ERR(regmap);
> +	}
> +	st->regmap = regmap;
> +
> +	ret = devm_add_action_or_reset(&spi->dev, ad5770r_disable_regulator,
> +				       st);

This should only be called 'after' we know there is something to do so...

> +	if (ret < 0)
> +		return ret;
> +
> +	st->vref_reg = devm_regulator_get_optional(&spi->dev, "vref");
> +	if (!IS_ERR(st->vref_reg)) {
> +		ret = regulator_enable(st->vref_reg);
> +		if (ret) {
> +			dev_err(&spi->dev,
> +				"Failed to enable vref regulators: %d\n", ret);
> +			return ret;
> +		}

call devm_add_action_or_reset(&spi->dev, ...disable_regulator here.

> +
> +		ret = regulator_get_voltage(st->vref_reg);
> +		if (ret < 0)
> +			return ret;
> +
> +		st->vref = ret / 1000;
> +	} else {
> +		if (PTR_ERR(st->vref_reg) == -ENODEV) {
> +			st->vref = AD5770R_LOW_VREF_mV;
> +			st->internal_ref = true;
> +		} else {
> +			return PTR_ERR(st->vref_reg);
> +		}
> +	}
> +
> +	indio_dev->dev.parent = &spi->dev;
> +	indio_dev->name = spi_get_device_id(spi)->name;
> +	indio_dev->info = &ad5770r_info;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->channels = ad5770r_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(ad5770r_channels);
> +
> +	ret = ad5770r_init(st);
> +	if (ret < 0) {
> +		dev_err(&spi->dev, "AD5770R init failed\n");
> +		return ret;
> +	}
> +
> +	return devm_iio_device_register(&st->spi->dev, indio_dev);
> +}
> +
> +static const struct of_device_id ad5770r_of_id[] = {
> +	{ .compatible = "adi,ad5770r", },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, ad5770r_of_id);
> +
> +static const struct spi_device_id ad5770r_id[] = {
> +	{ "ad5770r", 0 },
> +	{},

Given the driver needs a whole load of stuff that is in DT and
we have no other way of providing it, I think there is limited
point in provide the spi_device_id table (which is used for
probing via other ways such as the sysfs device add interface for
i2c).

> +};
> +MODULE_DEVICE_TABLE(spi, ad5770r_id);
> +
> +static struct spi_driver ad5770r_driver = {
> +	.driver = {
> +		.name = KBUILD_MODNAME,
> +		.of_match_table = of_match_ptr(ad5770r_of_id),

We could drop the of_match_ptr and make the driver probe-able
using ACPI and PRP001. This magic id is used to allow you to
probe using DT bindings via ACPI.

> +	},
> +	.probe = ad5770r_probe,
> +	.id_table = ad5770r_id,
> +};
> +
> +module_spi_driver(ad5770r_driver);
> +
> +MODULE_AUTHOR("Mircea Caprioru <mircea.caprioru@...log.com>");
> +MODULE_DESCRIPTION("Analog Devices AD5770R IDAC");
> +MODULE_LICENSE("GPL v2");

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