The AD3530/AD3530R (8-channel) and AD3531/AD3531R (4-channel) are
low-power, 16-bit, buffered voltage output DACs with software-
programmable gain controls, providing full-scale output spans of 2.5V or
5V for reference voltages of 2.5V. These devices operate from a single
2.7V to 5.5V supply and are guaranteed monotonic by design. The "R"
variants include a 2.5V, 5ppm/°C internal reference, which is disabled
by default.

Support for monitoring internal die temperature, output voltages, and
current of a selected channel via the MUXOUT pin using an external ADC
is currently not implemented.

Reviewed-by: David Lechner <dlechner@baylibre.com>
Signed-off-by: Kim Seer Paller <kimseer.paller@analog.com>
---
 MAINTAINERS               |   1 +
 drivers/iio/dac/Kconfig   |  11 +
 drivers/iio/dac/Makefile  |   1 +
 drivers/iio/dac/ad3530r.c | 503 ++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 516 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 4ca59fc1bf25aa49fecf78a90b2e1b73f25a2c05..25356d5a1a09e5ff6e7ed8eaa98a8ea990e79d8e 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1306,6 +1306,7 @@ L:	linux-iio@vger.kernel.org
 S:	Supported
 W:	https://ez.analog.com/linux-software-drivers
 F:	Documentation/devicetree/bindings/iio/dac/adi,ad3530r.yaml
+F:	drivers/iio/dac/ad3530r.c
 
 ANALOG DEVICES INC AD3552R DRIVER
 M:	Nuno Sá <nuno.sa@analog.com>
diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
index 4811ea973125a0dea1f8a9cdee1e0c045bc21981..e0996dc014a3d538ab6b4e0d50ff54ede50f1527 100644
--- a/drivers/iio/dac/Kconfig
+++ b/drivers/iio/dac/Kconfig
@@ -6,6 +6,17 @@
 
 menu "Digital to analog converters"
 
+config AD3530R
+	tristate "Analog Devices AD3530R and Similar DACs driver"
+	depends on SPI
+	select REGMAP_SPI
+	help
+	  Say yes here to build support for Analog Devices AD3530R, AD3531R
+	  Digital to Analog Converter.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called ad3530r.
+
 config AD3552R_HS
 	tristate "Analog Devices AD3552R DAC High Speed driver"
 	select AD3552R_LIB
diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile
index 8dd6cce81ed1152be4cf0af9ef877b5482ceb347..3684cd52b7fa9bc0ad9f855323dcbb2e4965c404 100644
--- a/drivers/iio/dac/Makefile
+++ b/drivers/iio/dac/Makefile
@@ -4,6 +4,7 @@
 #
 
 # When adding new entries keep the list in alphabetical order
+obj-$(CONFIG_AD3530R) += ad3530r.o
 obj-$(CONFIG_AD3552R_HS) += ad3552r-hs.o
 obj-$(CONFIG_AD3552R_LIB) += ad3552r-common.o
 obj-$(CONFIG_AD3552R) += ad3552r.o
diff --git a/drivers/iio/dac/ad3530r.c b/drivers/iio/dac/ad3530r.c
new file mode 100644
index 0000000000000000000000000000000000000000..05bd191e5225bd267f42ba36bbd42a18e6f22291
--- /dev/null
+++ b/drivers/iio/dac/ad3530r.c
@@ -0,0 +1,503 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * AD3530R/AD3530 8-channel, 16-bit Voltage Output DAC Driver
+ * AD3531R/AD3531 4-channel, 16-bit Voltage Output DAC Driver
+ *
+ * Copyright 2025 Analog Devices Inc.
+ */
+
+#include <linux/bitfield.h>
+#include <linux/bits.h>
+#include <linux/cleanup.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/gpio/consumer.h>
+#include <linux/iio/iio.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/mutex.h>
+#include <linux/property.h>
+#include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
+#include <linux/spi/spi.h>
+
+#define AD3530R_INTERFACE_CONFIG_A		0x00
+#define AD3530R_OUTPUT_OPERATING_MODE_0		0x20
+#define AD3530R_OUTPUT_OPERATING_MODE_1		0x21
+#define AD3530R_OUTPUT_CONTROL_0		0x2A
+#define AD3530R_REFERENCE_CONTROL_0		0x3C
+#define AD3530R_SW_LDAC_TRIG_A			0xE5
+#define AD3530R_INPUT_CH			0xEB
+#define AD3530R_MAX_REG_ADDR			0xF9
+
+#define AD3531R_SW_LDAC_TRIG_A			0xDD
+#define AD3531R_INPUT_CH			0xE3
+
+#define AD3530R_SLD_TRIG_A			BIT(7)
+#define AD3530R_OUTPUT_CONTROL_RANGE		BIT(2)
+#define AD3530R_REFERENCE_CONTROL_SEL		BIT(0)
+#define AD3530R_REG_VAL_MASK			GENMASK(15, 0)
+
+#define AD3530R_SW_RESET			(BIT(7) | BIT(0))
+#define AD3530R_MAX_CHANNELS			8
+#define AD3531R_MAX_CHANNELS			4
+#define AD3530R_INTERNAL_VREF_MV		2500
+#define AD3530R_LDAC_PULSE_US			100
+
+enum ad3530r_mode {
+	AD3530R_NORMAL_OPERATION,
+	AD3530R_POWERDOWN_1K,
+	AD3530R_POWERDOWN_7K7,
+	AD3530R_POWERDOWN_32K,
+};
+
+struct ad3530r_chan {
+	enum ad3530r_mode powerdown_mode;
+	bool powerdown;
+};
+
+struct ad3530r_chip_info {
+	const char *name;
+	const struct iio_chan_spec *channels;
+	int (*input_ch_reg)(unsigned int c);
+	unsigned int num_channels;
+	unsigned int sw_ldac_trig_reg;
+	bool internal_ref_support;
+};
+
+struct ad3530r_state {
+	struct regmap *regmap;
+	/* lock to protect against multiple access to the device and shared data */
+	struct mutex lock;
+	struct ad3530r_chan chan[AD3530R_MAX_CHANNELS];
+	const struct ad3530r_chip_info *chip_info;
+	struct gpio_desc *ldac_gpio;
+	int vref_mv;
+	/*
+	 * DMA (thus cache coherency maintenance) may require the transfer
+	 * buffers to live in their own cache lines.
+	 */
+	__be16 buf __aligned(IIO_DMA_MINALIGN);
+};
+
+static int ad3530r_input_ch_reg(unsigned int c)
+{
+	return 2 * c + AD3530R_INPUT_CH;
+}
+
+static int ad3531r_input_ch_reg(unsigned int c)
+{
+	return 2 * c + AD3531R_INPUT_CH;
+}
+
+static const char * const ad3530r_powerdown_modes[] = {
+	"1kohm_to_gnd",
+	"7.7kohm_to_gnd",
+	"32kohm_to_gnd",
+};
+
+static int ad3530r_get_powerdown_mode(struct iio_dev *indio_dev,
+				      const struct iio_chan_spec *chan)
+{
+	struct ad3530r_state *st = iio_priv(indio_dev);
+
+	guard(mutex)(&st->lock);
+	return st->chan[chan->channel].powerdown_mode - 1;
+}
+
+static int ad3530r_set_powerdown_mode(struct iio_dev *indio_dev,
+				      const struct iio_chan_spec *chan,
+				      unsigned int mode)
+{
+	struct ad3530r_state *st = iio_priv(indio_dev);
+
+	guard(mutex)(&st->lock);
+	st->chan[chan->channel].powerdown_mode = mode + 1;
+
+	return 0;
+}
+
+static const struct iio_enum ad3530r_powerdown_mode_enum = {
+	.items = ad3530r_powerdown_modes,
+	.num_items = ARRAY_SIZE(ad3530r_powerdown_modes),
+	.get = ad3530r_get_powerdown_mode,
+	.set = ad3530r_set_powerdown_mode,
+};
+
+static ssize_t ad3530r_get_dac_powerdown(struct iio_dev *indio_dev,
+					 uintptr_t private,
+					 const struct iio_chan_spec *chan,
+					 char *buf)
+{
+	struct ad3530r_state *st = iio_priv(indio_dev);
+
+	guard(mutex)(&st->lock);
+	return sysfs_emit(buf, "%d\n", st->chan[chan->channel].powerdown);
+}
+
+static ssize_t ad3530r_set_dac_powerdown(struct iio_dev *indio_dev,
+					 uintptr_t private,
+					 const struct iio_chan_spec *chan,
+					 const char *buf, size_t len)
+{
+	struct ad3530r_state *st = iio_priv(indio_dev);
+	int ret;
+	unsigned int mask, val, reg;
+	bool powerdown;
+
+	ret = kstrtobool(buf, &powerdown);
+	if (ret)
+		return ret;
+
+	guard(mutex)(&st->lock);
+	mask = GENMASK(chan->address + 1, chan->address);
+	reg = chan->channel < AD3531R_MAX_CHANNELS ?
+	      AD3530R_OUTPUT_OPERATING_MODE_0 :
+	      AD3530R_OUTPUT_OPERATING_MODE_1;
+	val = (powerdown ? st->chan[chan->channel].powerdown_mode : 0)
+	       << chan->address;
+
+	ret = regmap_update_bits(st->regmap, reg, mask, val);
+	if (ret)
+		return ret;
+
+	st->chan[chan->channel].powerdown = powerdown;
+
+	return len;
+}
+
+static int ad3530r_trigger_hw_ldac(struct gpio_desc *ldac_gpio)
+{
+	gpiod_set_value_cansleep(ldac_gpio, 1);
+	fsleep(AD3530R_LDAC_PULSE_US);
+	gpiod_set_value_cansleep(ldac_gpio, 0);
+
+	return 0;
+}
+
+static int ad3530r_dac_write(struct ad3530r_state *st, unsigned int chan,
+			     unsigned int val)
+{
+	int ret;
+
+	guard(mutex)(&st->lock);
+	st->buf = cpu_to_be16(val);
+
+	ret = regmap_bulk_write(st->regmap, st->chip_info->input_ch_reg(chan),
+				&st->buf, sizeof(st->buf));
+	if (ret)
+		return ret;
+
+	if (st->ldac_gpio)
+		return ad3530r_trigger_hw_ldac(st->ldac_gpio);
+
+	return regmap_set_bits(st->regmap, st->chip_info->sw_ldac_trig_reg,
+			       AD3530R_SLD_TRIG_A);
+}
+
+static int ad3530r_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int *val, int *val2, long info)
+{
+	struct ad3530r_state *st = iio_priv(indio_dev);
+	int ret;
+
+	guard(mutex)(&st->lock);
+	switch (info) {
+	case IIO_CHAN_INFO_RAW:
+		ret = regmap_bulk_read(st->regmap,
+				       st->chip_info->input_ch_reg(chan->channel),
+				       &st->buf, sizeof(st->buf));
+		if (ret)
+			return ret;
+
+		*val = FIELD_GET(AD3530R_REG_VAL_MASK, be16_to_cpu(st->buf));
+
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		*val = st->vref_mv;
+		*val2 = 16;
+
+		return IIO_VAL_FRACTIONAL_LOG2;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int ad3530r_write_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     int val, int val2, long info)
+{
+	struct ad3530r_state *st = iio_priv(indio_dev);
+
+	switch (info) {
+	case IIO_CHAN_INFO_RAW:
+		if (val < 0 || val > U16_MAX)
+			return -EINVAL;
+
+		return ad3530r_dac_write(st, chan->channel, val);
+	default:
+		return -EINVAL;
+	}
+}
+
+static int ad3530r_reg_access(struct iio_dev *indio_dev, unsigned int reg,
+			      unsigned int writeval, unsigned int *readval)
+{
+	struct ad3530r_state *st = iio_priv(indio_dev);
+
+	if (readval)
+		return regmap_read(st->regmap, reg, readval);
+
+	return regmap_write(st->regmap, reg, writeval);
+}
+
+static const struct iio_chan_spec_ext_info ad3530r_ext_info[] = {
+	{
+		.name = "powerdown",
+		.shared = IIO_SEPARATE,
+		.read = ad3530r_get_dac_powerdown,
+		.write = ad3530r_set_dac_powerdown,
+	},
+	IIO_ENUM("powerdown_mode", IIO_SEPARATE, &ad3530r_powerdown_mode_enum),
+	IIO_ENUM_AVAILABLE("powerdown_mode", IIO_SHARED_BY_TYPE,
+			   &ad3530r_powerdown_mode_enum),
+	{ }
+};
+
+#define AD3530R_CHAN(_chan, _pos) {					\
+	.type = IIO_VOLTAGE,						\
+	.indexed = 1,							\
+	.channel = _chan,						\
+	.address = _pos,						\
+	.output = 1,							\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |			\
+			      BIT(IIO_CHAN_INFO_SCALE),			\
+	.ext_info = ad3530r_ext_info,					\
+}
+
+static const struct iio_chan_spec ad3530r_channels[] = {
+	AD3530R_CHAN(0, 0),
+	AD3530R_CHAN(1, 2),
+	AD3530R_CHAN(2, 4),
+	AD3530R_CHAN(3, 6),
+	AD3530R_CHAN(4, 0),
+	AD3530R_CHAN(5, 2),
+	AD3530R_CHAN(6, 4),
+	AD3530R_CHAN(7, 6),
+};
+
+static const struct iio_chan_spec ad3531r_channels[] = {
+	AD3530R_CHAN(0, 0),
+	AD3530R_CHAN(1, 2),
+	AD3530R_CHAN(2, 4),
+	AD3530R_CHAN(3, 6),
+};
+
+static const struct ad3530r_chip_info ad3530_chip = {
+	.name = "ad3530",
+	.channels = ad3530r_channels,
+	.num_channels = ARRAY_SIZE(ad3530r_channels),
+	.sw_ldac_trig_reg = AD3530R_SW_LDAC_TRIG_A,
+	.input_ch_reg = ad3530r_input_ch_reg,
+	.internal_ref_support = false,
+};
+
+static const struct ad3530r_chip_info ad3530r_chip = {
+	.name = "ad3530r",
+	.channels = ad3530r_channels,
+	.num_channels = ARRAY_SIZE(ad3530r_channels),
+	.sw_ldac_trig_reg = AD3530R_SW_LDAC_TRIG_A,
+	.input_ch_reg = ad3530r_input_ch_reg,
+	.internal_ref_support = true,
+};
+
+static const struct ad3530r_chip_info ad3531_chip = {
+	.name = "ad3531",
+	.channels = ad3531r_channels,
+	.num_channels = ARRAY_SIZE(ad3531r_channels),
+	.sw_ldac_trig_reg = AD3531R_SW_LDAC_TRIG_A,
+	.input_ch_reg = ad3531r_input_ch_reg,
+	.internal_ref_support = false,
+};
+
+static const struct ad3530r_chip_info ad3531r_chip = {
+	.name = "ad3531r",
+	.channels = ad3531r_channels,
+	.num_channels = ARRAY_SIZE(ad3531r_channels),
+	.sw_ldac_trig_reg = AD3531R_SW_LDAC_TRIG_A,
+	.input_ch_reg = ad3531r_input_ch_reg,
+	.internal_ref_support = true,
+};
+
+static int ad3530r_setup(struct ad3530r_state *st, int vref,
+			 bool has_external_vref)
+{
+	struct device *dev = regmap_get_device(st->regmap);
+	struct gpio_desc *reset_gpio;
+	int i, ret;
+	u8 range_multiplier;
+
+	reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
+	if (IS_ERR(reset_gpio))
+		return dev_err_probe(dev, PTR_ERR(reset_gpio),
+				     "Failed to get reset GPIO\n");
+
+	if (reset_gpio) {
+		/* Perform hardware reset */
+		fsleep(1000);
+		gpiod_set_value_cansleep(reset_gpio, 0);
+	} else {
+		/* Perform software reset */
+		ret = regmap_update_bits(st->regmap, AD3530R_INTERFACE_CONFIG_A,
+					 AD3530R_SW_RESET, AD3530R_SW_RESET);
+		if (ret)
+			return ret;
+	}
+
+	fsleep(10000);
+
+	range_multiplier = 1;
+	if (device_property_read_bool(dev, "adi,range-double")) {
+		ret = regmap_set_bits(st->regmap, AD3530R_OUTPUT_CONTROL_0,
+				      AD3530R_OUTPUT_CONTROL_RANGE);
+		if (ret)
+			return ret;
+
+		range_multiplier = 2;
+	}
+
+	if (!has_external_vref && st->chip_info->internal_ref_support) {
+		ret = regmap_set_bits(st->regmap, AD3530R_REFERENCE_CONTROL_0,
+				      AD3530R_REFERENCE_CONTROL_SEL);
+		if (ret)
+			return ret;
+
+		st->vref_mv = range_multiplier * AD3530R_INTERNAL_VREF_MV;
+	}
+
+	if (has_external_vref)
+		st->vref_mv = range_multiplier * vref / 1000;
+
+	/* Set operating mode to normal operation. */
+	ret = regmap_write(st->regmap, AD3530R_OUTPUT_OPERATING_MODE_0,
+			   AD3530R_NORMAL_OPERATION);
+	if (ret)
+		return ret;
+
+	if (st->chip_info->num_channels > AD3531R_MAX_CHANNELS) {
+		ret = regmap_write(st->regmap, AD3530R_OUTPUT_OPERATING_MODE_1,
+				   AD3530R_NORMAL_OPERATION);
+		if (ret)
+			return ret;
+	}
+
+	for (i = 0; i < st->chip_info->num_channels; i++)
+		st->chan[i].powerdown_mode = AD3530R_POWERDOWN_32K;
+
+	st->ldac_gpio = devm_gpiod_get_optional(dev, "ldac", GPIOD_OUT_LOW);
+	if (IS_ERR(st->ldac_gpio))
+		return dev_err_probe(dev, PTR_ERR(st->ldac_gpio),
+				     "Failed to get ldac GPIO\n");
+
+	return 0;
+}
+
+static const struct regmap_config ad3530r_regmap_config = {
+	.reg_bits = 16,
+	.val_bits = 8,
+	.max_register = AD3530R_MAX_REG_ADDR,
+};
+
+static const struct iio_info ad3530r_info = {
+	.read_raw = ad3530r_read_raw,
+	.write_raw = ad3530r_write_raw,
+	.debugfs_reg_access = ad3530r_reg_access,
+};
+
+static int ad3530r_probe(struct spi_device *spi)
+{
+	static const char * const regulators[] = { "vdd", "iovdd" };
+	struct device *dev = &spi->dev;
+	struct iio_dev *indio_dev;
+	struct ad3530r_state *st;
+	bool has_external_vref;
+	int ret, vref;
+
+	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	st = iio_priv(indio_dev);
+
+	st->regmap = devm_regmap_init_spi(spi, &ad3530r_regmap_config);
+	if (IS_ERR(st->regmap))
+		return dev_err_probe(dev, PTR_ERR(st->regmap),
+				     "Failed to init regmap");
+
+	ret = devm_mutex_init(dev, &st->lock);
+	if (ret)
+		return ret;
+
+	st->chip_info = spi_get_device_match_data(spi);
+	if (!st->chip_info)
+		return -ENODEV;
+
+	ret = devm_regulator_bulk_get_enable(dev, ARRAY_SIZE(regulators),
+					     regulators);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to enable regulators\n");
+
+	vref = devm_regulator_get_enable_read_voltage(dev, "ref");
+	if (vref < 0 && vref != -ENODEV)
+		return vref;
+
+	has_external_vref = vref != -ENODEV;
+
+	if (!st->chip_info->internal_ref_support && !has_external_vref)
+		return -ENODEV;
+
+	ret = ad3530r_setup(st, vref, has_external_vref);
+	if (ret)
+		return ret;
+
+	indio_dev->name = st->chip_info->name;
+	indio_dev->info = &ad3530r_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = st->chip_info->channels;
+	indio_dev->num_channels = st->chip_info->num_channels;
+
+	return devm_iio_device_register(&spi->dev, indio_dev);
+}
+
+static const struct spi_device_id ad3530r_id[] = {
+	{ "ad3530", (kernel_ulong_t)&ad3530_chip },
+	{ "ad3530r", (kernel_ulong_t)&ad3530r_chip },
+	{ "ad3531", (kernel_ulong_t)&ad3531_chip },
+	{ "ad3531r", (kernel_ulong_t)&ad3531r_chip },
+	{ }
+};
+MODULE_DEVICE_TABLE(spi, ad3530r_id);
+
+static const struct of_device_id ad3530r_of_match[] = {
+	{ .compatible = "adi,ad3530", .data = &ad3530_chip },
+	{ .compatible = "adi,ad3530r", .data = &ad3530r_chip },
+	{ .compatible = "adi,ad3531", .data = &ad3531_chip },
+	{ .compatible = "adi,ad3531r", .data = &ad3531r_chip },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, ad3530r_of_match);
+
+static struct spi_driver ad3530r_driver = {
+	.driver = {
+		.name = "ad3530r",
+		.of_match_table = ad3530r_of_match,
+	},
+	.probe = ad3530r_probe,
+	.id_table = ad3530r_id,
+};
+module_spi_driver(ad3530r_driver);
+
+MODULE_AUTHOR("Kim Seer Paller <kimseer.paller@analog.com>");
+MODULE_DESCRIPTION("Analog Devices AD3530R and Similar DACs Driver");
+MODULE_LICENSE("GPL");

-- 
2.34.1

On Mon, Apr 21, 2025 at 12:24:54PM +0800, Kim Seer Paller wrote:
> The AD3530/AD3530R (8-channel) and AD3531/AD3531R (4-channel) are
> low-power, 16-bit, buffered voltage output DACs with software-
> programmable gain controls, providing full-scale output spans of 2.5V or
> 5V for reference voltages of 2.5V. These devices operate from a single
> 2.7V to 5.5V supply and are guaranteed monotonic by design. The "R"
> variants include a 2.5V, 5ppm/°C internal reference, which is disabled
> by default.
> 
> Support for monitoring internal die temperature, output voltages, and
> current of a selected channel via the MUXOUT pin using an external ADC
> is currently not implemented.

...

> +#include <linux/bitfield.h>
> +#include <linux/bits.h>
> +#include <linux/cleanup.h>
> +#include <linux/delay.h>

> +#include <linux/device.h>

I don't see how you use this. But

+ dev_printk.h

> +#include <linux/gpio/consumer.h>
> +#include <linux/iio/iio.h>
> +#include <linux/module.h>
> +#include <linux/mod_devicetable.h>
> +#include <linux/mutex.h>
> +#include <linux/property.h>
> +#include <linux/regmap.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/spi/spi.h>

...

> +#define AD3530R_SW_RESET			(BIT(7) | BIT(0))

> +#define AD3530R_MAX_CHANNELS			8
> +#define AD3531R_MAX_CHANNELS			4

Sounds to me that these two shouldn't be grouped with the rest here. Perhaps
move them out to after the LDAC_PULSE?

> +#define AD3530R_INTERNAL_VREF_MV		2500

_mV (yes, with Volts and Amperes we use proper spelling).

> +#define AD3530R_LDAC_PULSE_US			100

...

> +	int (*input_ch_reg)(unsigned int c);

c? channel?

...

> +	int vref_mv;

_mV

...

> +static int ad3530r_input_ch_reg(unsigned int c)
> +{
> +	return 2 * c + AD3530R_INPUT_CH;
> +}
> +
> +static int ad3531r_input_ch_reg(unsigned int c)
> +{
> +	return 2 * c + AD3531R_INPUT_CH;
> +}

c --> channel

...

> +static const char * const ad3530r_powerdown_modes[] = {
> +	"1kohm_to_gnd",

kOhm

> +	"7.7kohm_to_gnd",

Ditto.

> +	"32kohm_to_gnd",

Ditto.

> +};

...

> +static const struct iio_enum ad3530r_powerdown_mode_enum = {
> +	.items = ad3530r_powerdown_modes,
> +	.num_items = ARRAY_SIZE(ad3530r_powerdown_modes),

+ array_size.h

> +	.get = ad3530r_get_powerdown_mode,
> +	.set = ad3530r_set_powerdown_mode,
> +};

...

> +static ssize_t ad3530r_get_dac_powerdown(struct iio_dev *indio_dev,
> +					 uintptr_t private,
> +					 const struct iio_chan_spec *chan,
> +					 char *buf)
> +{
> +	struct ad3530r_state *st = iio_priv(indio_dev);
> +
> +	guard(mutex)(&st->lock);
> +	return sysfs_emit(buf, "%d\n", st->chan[chan->channel].powerdown);

+ sysfs.h

> +}

...

> +static ssize_t ad3530r_set_dac_powerdown(struct iio_dev *indio_dev,
> +					 uintptr_t private,
> +					 const struct iio_chan_spec *chan,
> +					 const char *buf, size_t len)
> +{
> +	struct ad3530r_state *st = iio_priv(indio_dev);
> +	int ret;
> +	unsigned int mask, val, reg;
> +	bool powerdown;
> +
> +	ret = kstrtobool(buf, &powerdown);

+ kstrtox.h

> +	if (ret)
> +		return ret;
> +
> +	guard(mutex)(&st->lock);
> +	mask = GENMASK(chan->address + 1, chan->address);
> +	reg = chan->channel < AD3531R_MAX_CHANNELS ?
> +	      AD3530R_OUTPUT_OPERATING_MODE_0 :
> +	      AD3530R_OUTPUT_OPERATING_MODE_1;
> +	val = (powerdown ? st->chan[chan->channel].powerdown_mode : 0)
> +	       << chan->address;

Please, move the operator to the previous line, Or even

	... pdmode;

	pdmode = powerdown ? st->chan[chan->channel].powerdown_mode : 0;
	val = pdmode << ...;

> +	ret = regmap_update_bits(st->regmap, reg, mask, val);
> +	if (ret)
> +		return ret;
> +
> +	st->chan[chan->channel].powerdown = powerdown;
> +
> +	return len;
> +}

...

> +	struct ad3530r_state *st = iio_priv(indio_dev);
> +
> +	switch (info) {
> +	case IIO_CHAN_INFO_RAW:
> +		if (val < 0 || val > U16_MAX)

U16_MAX is an abstract type with this limit, do you have any predefined HW
limit instead? Probably better to use that one as defined via BIT() / GENMASK().

> +			return -EINVAL;
> +
> +		return ad3530r_dac_write(st, chan->channel, val);
> +	default:
> +		return -EINVAL;
> +	}

...

> +static const struct iio_chan_spec_ext_info ad3530r_ext_info[] = {
> +	{
> +		.name = "powerdown",
> +		.shared = IIO_SEPARATE,
> +		.read = ad3530r_get_dac_powerdown,
> +		.write = ad3530r_set_dac_powerdown,
> +	},
> +	IIO_ENUM("powerdown_mode", IIO_SEPARATE, &ad3530r_powerdown_mode_enum),
> +	IIO_ENUM_AVAILABLE("powerdown_mode", IIO_SHARED_BY_TYPE,
> +			   &ad3530r_powerdown_mode_enum),
> +	{ }
> +};
> +
> +#define AD3530R_CHAN(_chan, _pos) {					\

Slightly better to have the curly braces on the same column as it's easier to
read.

#define AD3530R_CHAN(_chan, _pos)				\
{								\

(and make it one TAB less for the backslash).

> +	.type = IIO_VOLTAGE,						\
> +	.indexed = 1,							\
> +	.channel = _chan,						\
> +	.address = _pos,						\
> +	.output = 1,							\
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |			\
> +			      BIT(IIO_CHAN_INFO_SCALE),			\
> +	.ext_info = ad3530r_ext_info,					\
> +}

...

> +static int ad3530r_setup(struct ad3530r_state *st, int vref,
> +			 bool has_external_vref)
> +{
> +	struct device *dev = regmap_get_device(st->regmap);
> +	struct gpio_desc *reset_gpio;
> +	int i, ret;
> +	u8 range_multiplier;

+ types.h (and especially for boolean type along with true/false definitions.

> +
> +	reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
> +	if (IS_ERR(reset_gpio))
> +		return dev_err_probe(dev, PTR_ERR(reset_gpio),
> +				     "Failed to get reset GPIO\n");

+ err.h

> +	if (reset_gpio) {
> +		/* Perform hardware reset */
> +		fsleep(1000);

(1 * USEC_PER_MSEC) ?

> +		gpiod_set_value_cansleep(reset_gpio, 0);
> +	} else {
> +		/* Perform software reset */
> +		ret = regmap_update_bits(st->regmap, AD3530R_INTERFACE_CONFIG_A,
> +					 AD3530R_SW_RESET, AD3530R_SW_RESET);
> +		if (ret)
> +			return ret;
> +	}

> +	fsleep(10000);

10 * USEC_PER_MSEC

With these constants it's less error prone (when 3 or more zeroes) and easier
to get the units without looking into fsleep() implementation / documentation.

> +	range_multiplier = 1;
> +	if (device_property_read_bool(dev, "adi,range-double")) {
> +		ret = regmap_set_bits(st->regmap, AD3530R_OUTPUT_CONTROL_0,
> +				      AD3530R_OUTPUT_CONTROL_RANGE);
> +		if (ret)
> +			return ret;
> +
> +		range_multiplier = 2;
> +	}
> +
> +	if (!has_external_vref && st->chip_info->internal_ref_support) {
> +		ret = regmap_set_bits(st->regmap, AD3530R_REFERENCE_CONTROL_0,
> +				      AD3530R_REFERENCE_CONTROL_SEL);
> +		if (ret)
> +			return ret;
> +
> +		st->vref_mv = range_multiplier * AD3530R_INTERNAL_VREF_MV;
> +	}
> +
> +	if (has_external_vref)
> +		st->vref_mv = range_multiplier * vref / 1000;

MILLI?


> +	/* Set operating mode to normal operation. */
> +	ret = regmap_write(st->regmap, AD3530R_OUTPUT_OPERATING_MODE_0,
> +			   AD3530R_NORMAL_OPERATION);
> +	if (ret)
> +		return ret;
> +
> +	if (st->chip_info->num_channels > AD3531R_MAX_CHANNELS) {
> +		ret = regmap_write(st->regmap, AD3530R_OUTPUT_OPERATING_MODE_1,
> +				   AD3530R_NORMAL_OPERATION);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	for (i = 0; i < st->chip_info->num_channels; i++)
> +		st->chan[i].powerdown_mode = AD3530R_POWERDOWN_32K;
> +
> +	st->ldac_gpio = devm_gpiod_get_optional(dev, "ldac", GPIOD_OUT_LOW);
> +	if (IS_ERR(st->ldac_gpio))
> +		return dev_err_probe(dev, PTR_ERR(st->ldac_gpio),
> +				     "Failed to get ldac GPIO\n");
> +
> +	return 0;
> +}

...

> +	vref = devm_regulator_get_enable_read_voltage(dev, "ref");
> +	if (vref < 0 && vref != -ENODEV)
> +		return vref;
> +
> +	has_external_vref = vref != -ENODEV;

Wouldn't be better just make this 0 when it's == -ENODEV and check just the
value without having this additional boolean variable (note, I haven't checked
the meaning of Vref == 0 in case it's possible in real life and hardware
behaves adequately)?

> +	if (!st->chip_info->internal_ref_support && !has_external_vref)
> +		return -ENODEV;

> +	ret = ad3530r_setup(st, vref, has_external_vref);
> +	if (ret)
> +		return ret;

-- 
With Best Regards,
Andy Shevchenko

On 4/22/25 10:11 AM, Andy Shevchenko wrote:
> On Mon, Apr 21, 2025 at 12:24:54PM +0800, Kim Seer Paller wrote:

...

> 
>> +#define AD3530R_INTERNAL_VREF_MV		2500
> 
> _mV (yes, with Volts and Amperes we use proper spelling).

When did we start doing that? No one asked me to do this in any of the new
drivers I did in the last year, so I didn't know this was a thing we should
be doing.


> 
>> +#define AD3530R_LDAC_PULSE_US			100
> 
> ...
> 
>> +	int (*input_ch_reg)(unsigned int c);
> 
> c? channel?
> 
> ...
> 
>> +	int vref_mv;
> 
> _mV
> 
> ...
> 
>> +static int ad3530r_input_ch_reg(unsigned int c)
>> +{
>> +	return 2 * c + AD3530R_INPUT_CH;
>> +}
>> +
>> +static int ad3531r_input_ch_reg(unsigned int c)
>> +{
>> +	return 2 * c + AD3531R_INPUT_CH;
>> +}
> 
> c --> channel
> 
> ...
> 
>> +static const char * const ad3530r_powerdown_modes[] = {
>> +	"1kohm_to_gnd",
> 
> kOhm
> 
>> +	"7.7kohm_to_gnd",
> 
> Ditto.
> 
>> +	"32kohm_to_gnd",
> 
> Ditto.

These are defined by sysfs ABI, so can't be changed otherwise it would break
userspace.

Comes from...
What:		/sys/bus/iio/devices/iio:deviceX/out_voltageY_powerdown_mode

> 
>> +};
>

On Tue, Apr 22, 2025 at 11:37:06AM -0500, David Lechner wrote:
> On 4/22/25 10:11 AM, Andy Shevchenko wrote:
> > On Mon, Apr 21, 2025 at 12:24:54PM +0800, Kim Seer Paller wrote:

...

> >> +#define AD3530R_INTERNAL_VREF_MV		2500
> > 
> > _mV (yes, with Volts and Amperes we use proper spelling).
> 
> When did we start doing that? No one asked me to do this in any of the new
> drivers I did in the last year, so I didn't know this was a thing we should
> be doing.

I remember a discussion for one driver a year or so ago. But I can't find
quickly a reference. The rationale is to be as closer as possible to real
world (physics). And, for instance, regulator framework does that already.
It's a pity not many people aware...

...

> >> +static const char * const ad3530r_powerdown_modes[] = {
> >> +	"1kohm_to_gnd",
> > 
> > kOhm
> > 
> >> +	"7.7kohm_to_gnd",
> > 
> > Ditto.
> > 
> >> +	"32kohm_to_gnd",
> > 
> > Ditto.
> 
> These are defined by sysfs ABI, so can't be changed otherwise it would break
> userspace.

Ah, okay then.

> Comes from...
> What:		/sys/bus/iio/devices/iio:deviceX/out_voltageY_powerdown_mode

> >> +};

-- 
With Best Regards,
Andy Shevchenko

On Mon, 21 Apr 2025 12:24:54 +0800
Kim Seer Paller <kimseer.paller@analog.com> wrote:

> The AD3530/AD3530R (8-channel) and AD3531/AD3531R (4-channel) are
> low-power, 16-bit, buffered voltage output DACs with software-
> programmable gain controls, providing full-scale output spans of 2.5V or
> 5V for reference voltages of 2.5V. These devices operate from a single
> 2.7V to 5.5V supply and are guaranteed monotonic by design. The "R"
> variants include a 2.5V, 5ppm/°C internal reference, which is disabled
> by default.
> 
> Support for monitoring internal die temperature, output voltages, and
> current of a selected channel via the MUXOUT pin using an external ADC
> is currently not implemented.
> 
> Reviewed-by: David Lechner <dlechner@baylibre.com>
> Signed-off-by: Kim Seer Paller <kimseer.paller@analog.com>
Hi.

Just one thing from a final pre merge look through.

The initialization of powerdown mode works but only because the NORMAL
mode == 0.  That should be setting it explicitly for each set of 4 channels
as needed.

I don't really mind how you solve that.  There are lots of options
to build up the 4 fields in each of those registers.

Jonathan

> diff --git a/drivers/iio/dac/ad3530r.c b/drivers/iio/dac/ad3530r.c
> new file mode 100644
> index 0000000000000000000000000000000000000000..05bd191e5225bd267f42ba36bbd42a18e6f22291
> --- /dev/null
> +++ b/drivers/iio/dac/ad3530r.c
> @@ -0,0 +1,503 @@

> +
> +static ssize_t ad3530r_set_dac_powerdown(struct iio_dev *indio_dev,
> +					 uintptr_t private,
> +					 const struct iio_chan_spec *chan,
> +					 const char *buf, size_t len)
> +{
> +	struct ad3530r_state *st = iio_priv(indio_dev);
> +	int ret;
> +	unsigned int mask, val, reg;
> +	bool powerdown;
> +
> +	ret = kstrtobool(buf, &powerdown);
> +	if (ret)
> +		return ret;
> +
> +	guard(mutex)(&st->lock);
> +	mask = GENMASK(chan->address + 1, chan->address);

I think maybe we need a macro to get the mask from the channel number?
Using address for this seems overkill given how simple that maths is.
Ideally that macro could perhaps be used in the code below to avoid
all the defines I suggested.


> +	reg = chan->channel < AD3531R_MAX_CHANNELS ?
> +	      AD3530R_OUTPUT_OPERATING_MODE_0 :
> +	      AD3530R_OUTPUT_OPERATING_MODE_1;
> +	val = (powerdown ? st->chan[chan->channel].powerdown_mode : 0)
> +	       << chan->address;
> +


> +static int ad3530r_setup(struct ad3530r_state *st, int vref,
> +			 bool has_external_vref)
> +{

> +
> +	if (has_external_vref)
> +		st->vref_mv = range_multiplier * vref / 1000;
> +
> +	/* Set operating mode to normal operation. */
> +	ret = regmap_write(st->regmap, AD3530R_OUTPUT_OPERATING_MODE_0,
> +			   AD3530R_NORMAL_OPERATION);
Is this actually doing that?  I think the register is lots of 2 bit
fields and this is only setting it for the first channel?

This works because that value is 0.  Logically however we should set it
to
	(AD3530R_NORMAL_OPERATION << 6) |
	(AD3530R_NORMAL_OPERATION << 4) |
	(AD3530R_NORMAL_OPERATION << 2) |
	(AD3530R_NORMAL_OPERATION << 0)

Or possibly better as

	FIELD_PREP(AD3530R_OP_MODE_0_CHAN0_MSK, AD3530R_NORMAL_OPERATION) |
	FIELD_PREP(AD3530R_OP_MODE_0_CHAN1_MSK, AD3530R_NORMAL_OPERATION) |

etc

Names are a bit long, so maybe consider shortening some of the defines.

> +	if (ret)
> +		return ret;
> +
> +	if (st->chip_info->num_channels > AD3531R_MAX_CHANNELS) {

If we have it explicit that we have multiple fields this will become more obvious.
However I'd use the number 4 here rather than the number of channels the AD3531R happens
to have.


> +		ret = regmap_write(st->regmap, AD3530R_OUTPUT_OPERATING_MODE_1,
> +				   AD3530R_NORMAL_OPERATION);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	for (i = 0; i < st->chip_info->num_channels; i++)
> +		st->chan[i].powerdown_mode = AD3530R_POWERDOWN_32K;
> +
> +	st->ldac_gpio = devm_gpiod_get_optional(dev, "ldac", GPIOD_OUT_LOW);
> +	if (IS_ERR(st->ldac_gpio))
> +		return dev_err_probe(dev, PTR_ERR(st->ldac_gpio),
> +				     "Failed to get ldac GPIO\n");
> +
> +	return 0;
> +}
> +
> +static const struct regmap_config ad3530r_regmap_config = {
> +	.reg_bits = 16,
> +	.val_bits = 8,
> +	.max_register = AD3530R_MAX_REG_ADDR,
> +};