iio: dac: ad5706r: Add support for AD5706R DAC

Add support for the Analog Devices AD5706R, a 4-channel 16-bit
current output digital-to-analog converter with SPI interface.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Alexis Czezar Torreno <alexisczezar.torreno@analog.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

Author: actorreno

MAINTAINERS

@@ -1504,6 +1504,7 @@ L:	linux-iio@vger.kernel.org
 S:	Supported
 W:	https://ez.analog.com/linux-software-drivers
 F:	Documentation/devicetree/bindings/iio/dac/adi,ad5706r.yaml
+F:	drivers/iio/dac/ad5706r.c
 
 ANALOG DEVICES INC AD7091R DRIVER
 M:	Marcelo Schmitt <marcelo.schmitt@analog.com>

drivers/iio/dac/Kconfig

@@ -178,6 +178,17 @@ config AD5624R_SPI
 	  Say yes here to build support for Analog Devices AD5624R, AD5644R and
 	  AD5664R converters (DAC). This driver uses the common SPI interface.
 
+config AD5706R
+	tristate "Analog Devices AD5706R DAC driver"
+	depends on SPI
+	select REGMAP
+	help
+	  Say yes here to build support for Analog Devices AD5706R 4-channel,
+	  16-bit current output DAC.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called ad5706r.
+
 config AD9739A
 	tristate "Analog Devices AD9739A RF DAC spi driver"
 	depends on SPI

drivers/iio/dac/Makefile

@@ -21,6 +21,7 @@ obj-$(CONFIG_AD5449) += ad5449.o
 obj-$(CONFIG_AD5592R_BASE) += ad5592r-base.o
 obj-$(CONFIG_AD5592R) += ad5592r.o
 obj-$(CONFIG_AD5593R) += ad5593r.o
+obj-$(CONFIG_AD5706R) += ad5706r.o
 obj-$(CONFIG_AD5755) += ad5755.o
 obj-$(CONFIG_AD5758) += ad5758.o
 obj-$(CONFIG_AD5761) += ad5761.o

drivers/iio/dac/ad5706r.c

@@ -0,0 +1,253 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * AD5706R 16-bit Current Output Digital to Analog Converter
+ *
+ * Copyright 2026 Analog Devices Inc.
+ */
+
+#include <linux/array_size.h>
+#include <linux/bits.h>
+#include <linux/dev_printk.h>
+#include <linux/err.h>
+#include <linux/iio/iio.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/spi/spi.h>
+#include <linux/types.h>
+#include <linux/unaligned.h>
+
+/* SPI frame layout */
+#define AD5706R_RD_MASK			BIT(15)
+#define AD5706R_ADDR_MASK		GENMASK(11, 0)
+
+/* Registers */
+#define AD5706R_REG_DAC_INPUT_A_CH(x)		(0x60 + ((x) * 2))
+#define AD5706R_REG_DAC_DATA_READBACK_CH(x)	(0x68 + ((x) * 2))
+
+#define AD5706R_DAC_RESOLUTION		16
+#define AD5706R_DAC_MAX_CODE		GENMASK(15, 0)
+#define AD5706R_MULTIBYTE_REG_START	0x14
+#define AD5706R_MULTIBYTE_REG_END	0x71
+#define AD5706R_MAX_REG			0x77
+
+struct ad5706r_state {
+	struct spi_device *spi;
+	struct regmap *regmap;
+
+	u8 tx_buf[4] __aligned(IIO_DMA_MINALIGN);
+	u8 rx_buf[4];
+};
+
+static int ad5706r_reg_len(unsigned int reg)
+{
+	if (reg >= AD5706R_MULTIBYTE_REG_START && reg <= AD5706R_MULTIBYTE_REG_END)
+		return 2;
+
+	return 1;
+}
+
+static int ad5706r_regmap_write(void *context, const void *data, size_t count)
+{
+	struct ad5706r_state *st = context;
+	unsigned int num_bytes;
+	u16 reg, val;
+
+	if (count != 4)
+		return -EINVAL;
+
+	reg = get_unaligned_be16(data);
+	val = get_unaligned_be16(data + 2);
+	num_bytes = ad5706r_reg_len(reg);
+
+	struct spi_transfer xfer = {
+		.tx_buf = st->tx_buf,
+		.len = num_bytes + 2,
+	};
+
+	put_unaligned_be16(reg, &st->tx_buf[0]);
+
+	if (num_bytes == 1)
+		st->tx_buf[2] = (u8)val;
+	else if (num_bytes == 2)
+		put_unaligned_be16(val, &st->tx_buf[2]);
+	else
+		return -EINVAL;
+
+	return spi_sync_transfer(st->spi, &xfer, 1);
+}
+
+static int ad5706r_regmap_read(void *context, const void *reg_buf,
+			       size_t reg_size, void *val_buf, size_t val_size)
+{
+	struct ad5706r_state *st = context;
+	unsigned int num_bytes;
+	u16 reg, cmd, val;
+	int ret;
+
+	if (reg_size != 2 || val_size != 2)
+		return -EINVAL;
+
+	reg = get_unaligned_be16(reg_buf);
+	num_bytes = ad5706r_reg_len(reg);
+
+	/* Full duplex, device responds immediately after command */
+	struct spi_transfer xfer = {
+		.tx_buf = st->tx_buf,
+		.rx_buf = st->rx_buf,
+		.len = 2 + num_bytes,
+	};
+
+	cmd = AD5706R_RD_MASK | (reg & AD5706R_ADDR_MASK);
+	put_unaligned_be16(cmd, &st->tx_buf[0]);
+	put_unaligned_be16(0, &st->tx_buf[2]);
+
+	ret = spi_sync_transfer(st->spi, &xfer, 1);
+	if (ret)
+		return ret;
+
+	/* Extract value from response (skip 2-byte command echo) */
+	if (num_bytes == 1)
+		val = st->rx_buf[2];
+	else if (num_bytes == 2)
+		val = get_unaligned_be16(&st->rx_buf[2]);
+	else
+		return -EINVAL;
+
+	put_unaligned_be16(val, val_buf);
+
+	return 0;
+}
+
+static int ad5706r_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int *val, int *val2, long mask)
+{
+	struct ad5706r_state *st = iio_priv(indio_dev);
+	unsigned int reg, reg_val;
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		reg = AD5706R_REG_DAC_DATA_READBACK_CH(chan->channel);
+		ret = regmap_read(st->regmap, reg, &reg_val);
+		if (ret)
+			return ret;
+
+		*val = reg_val;
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		*val = 50;
+		*val2 = AD5706R_DAC_RESOLUTION;
+		return IIO_VAL_FRACTIONAL_LOG2;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int ad5706r_write_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     int val, int val2, long mask)
+{
+	struct ad5706r_state *st = iio_priv(indio_dev);
+	unsigned int reg;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		if (val < 0 || val > AD5706R_DAC_MAX_CODE)
+			return -EINVAL;
+
+		reg = AD5706R_REG_DAC_INPUT_A_CH(chan->channel);
+		return regmap_write(st->regmap, reg, val);
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct regmap_bus ad5706r_regmap_bus = {
+	.write = ad5706r_regmap_write,
+	.read = ad5706r_regmap_read,
+	.reg_format_endian_default = REGMAP_ENDIAN_BIG,
+	.val_format_endian_default = REGMAP_ENDIAN_BIG,
+};
+
+static const struct regmap_config ad5706r_regmap_config = {
+	.reg_bits = 16,
+	.val_bits = 16,
+	.max_register = AD5706R_MAX_REG,
+};
+
+static const struct iio_info ad5706r_info = {
+	.read_raw = ad5706r_read_raw,
+	.write_raw = ad5706r_write_raw,
+};
+
+#define AD5706R_CHAN(_channel) {				\
+	.type = IIO_CURRENT,					\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |		\
+			      BIT(IIO_CHAN_INFO_SCALE),		\
+	.output = 1,						\
+	.indexed = 1,						\
+	.channel = _channel,					\
+}
+
+static const struct iio_chan_spec ad5706r_channels[] = {
+	AD5706R_CHAN(0),
+	AD5706R_CHAN(1),
+	AD5706R_CHAN(2),
+	AD5706R_CHAN(3),
+};
+
+static int ad5706r_probe(struct spi_device *spi)
+{
+	struct device *dev = &spi->dev;
+	struct iio_dev *indio_dev;
+	struct ad5706r_state *st;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	st = iio_priv(indio_dev);
+	st->spi = spi;
+
+	st->regmap = devm_regmap_init(dev, &ad5706r_regmap_bus,
+				      st, &ad5706r_regmap_config);
+	if (IS_ERR(st->regmap))
+		return dev_err_probe(dev, PTR_ERR(st->regmap),
+				     "Failed to init regmap\n");
+
+	indio_dev->name = "ad5706r";
+	indio_dev->info = &ad5706r_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = ad5706r_channels;
+	indio_dev->num_channels = ARRAY_SIZE(ad5706r_channels);
+
+	return devm_iio_device_register(dev, indio_dev);
+}
+
+static const struct of_device_id ad5706r_of_match[] = {
+	{ .compatible = "adi,ad5706r" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, ad5706r_of_match);
+
+static const struct spi_device_id ad5706r_id[] = {
+	{ "ad5706r" },
+	{ }
+};
+MODULE_DEVICE_TABLE(spi, ad5706r_id);
+
+static struct spi_driver ad5706r_driver = {
+	.driver = {
+		.name = "ad5706r",
+		.of_match_table = ad5706r_of_match,
+	},
+	.probe = ad5706r_probe,
+	.id_table = ad5706r_id,
+};
+module_spi_driver(ad5706r_driver);
+
+MODULE_AUTHOR("Alexis Czezar Torreno <alexisczezar.torreno@analog.com>");
+MODULE_DESCRIPTION("AD5706R 16-bit Current Output DAC driver");
+MODULE_LICENSE("GPL");