[PATCH v2 2/3] iio: dac: ad5706r: Add support for AD5706R DAC
From: Alexis Czezar Torreno
Date: Tue Mar 10 2026 - 20:25:43 EST
Add support for the Analog Devices AD5706R, a 4-channel 16-bit
current output digital-to-analog converter with SPI interface.
Features:
- 4 independent DAC channels
- Hardware and software LDAC trigger
- Configurable output range
- PWM-based LDAC control
- Dither and toggle modes
- Dynamically configurable SPI speed
Signed-off-by: Alexis Czezar Torreno <alexisczezar.torreno@xxxxxxxxxx>
---
Changes since v1:
- Removed PWM, GPIO, clock generator, debugfs, regmap, IIO_BUFFER
- Removed all custom ext_info sysfs attributes
- Simplified to basic raw read/write and read-only scale
- SPI read/write can handle multibyte registers
---
---
drivers/iio/dac/Kconfig | 10 +++
drivers/iio/dac/Makefile | 1 +
drivers/iio/dac/ad5706r.c | 208 ++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 219 insertions(+)
diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
index db9f5c711b3df90641f017652fbbef594cc1627d..8ccbdf6dfbca8640a47bf05b4afc6b4bf90a7e26 100644
--- a/drivers/iio/dac/Kconfig
+++ b/drivers/iio/dac/Kconfig
@@ -178,6 +178,16 @@ 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
+ 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
diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile
index 2a80bbf4e80ad557da79ed916027cedff286984b..0034317984985035f7987a744899924bfd4612e3 100644
--- a/drivers/iio/dac/Makefile
+++ b/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
diff --git a/drivers/iio/dac/ad5706r.c b/drivers/iio/dac/ad5706r.c
new file mode 100644
index 0000000000000000000000000000000000000000..204d29f6495da167e922e5c9c5a2c4ff5c650693
--- /dev/null
+++ b/drivers/iio/dac/ad5706r.c
@@ -0,0 +1,208 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * AD5706R 16-bit Current Output Digital to Analog Converter
+ *
+ * Copyright 2026 Analog Devices Inc.
+ */
+
+#include <linux/device.h>
+#include <linux/iio/iio.h>
+#include <linux/module.h>
+#include <linux/spi/spi.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 BIT(AD5706R_DAC_RESOLUTION) /* 65536 */
+#define AD5706R_MULTIBYTE_REG_START 0x14
+#define AD5706R_MULTIBYTE_REG_END 0x71
+#define AD5706R_SINGLE_BYTE_LEN 1
+#define AD5706R_DOUBLE_BYTE_LEN 2
+
+struct ad5706r_state {
+ struct spi_device *spi;
+ struct mutex lock; /* Protects SPI transfers */
+
+ __be32 tx_buf __aligned(ARCH_DMA_MINALIGN);
+ __be16 rx_buf;
+};
+
+static int ad5706r_reg_len(unsigned int reg)
+{
+ if (reg >= AD5706R_MULTIBYTE_REG_START && reg <= AD5706R_MULTIBYTE_REG_END)
+ return AD5706R_DOUBLE_BYTE_LEN;
+
+ return AD5706R_SINGLE_BYTE_LEN;
+}
+
+static int ad5706r_spi_write(struct ad5706r_state *st, u16 reg, u16 val)
+{
+ unsigned int num_bytes = ad5706r_reg_len(reg);
+
+ struct spi_transfer xfer = {
+ .tx_buf = &st->tx_buf,
+ .len = num_bytes + 2,
+ };
+
+ st->tx_buf = cpu_to_be32((((u32)reg) << 16) |
+ ((u32)val << (16 - (num_bytes * 8))));
+
+ return spi_sync_transfer(st->spi, &xfer, 1);
+}
+
+static int ad5706r_spi_read(struct ad5706r_state *st, u16 reg, u16 *val)
+{
+ unsigned int num_bytes = ad5706r_reg_len(reg);
+ u16 cmd;
+ int ret;
+
+ struct spi_transfer xfer[] = {
+ {
+ .tx_buf = &st->tx_buf,
+ .len = 2,
+ },
+ {
+ .rx_buf = &st->rx_buf,
+ .len = num_bytes,
+ },
+ };
+
+ cmd = AD5706R_RD_MASK | (reg & AD5706R_ADDR_MASK);
+ st->tx_buf = cpu_to_be32((u32)cmd << 16);
+
+ ret = spi_sync_transfer(st->spi, xfer, ARRAY_SIZE(xfer));
+ if (ret)
+ return ret;
+
+ *val = be16_to_cpu(st->rx_buf) >> (16 - (num_bytes * 8));
+
+ 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);
+ u16 reg_val;
+ int ret;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_RAW:
+ scoped_guard(mutex, &st->lock) {
+ ret = ad5706r_spi_read(st, AD5706R_REG_DAC_DATA_READBACK_CH(chan->channel),
+ ®_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;
+ }
+
+ 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);
+
+ switch (mask) {
+ case IIO_CHAN_INFO_RAW:
+ if (val < 0 || val >= AD5706R_DAC_MAX_CODE)
+ return -EINVAL;
+
+ guard(mutex)(&st->lock);
+ return ad5706r_spi_write(st,
+ AD5706R_REG_DAC_INPUT_A_CH(chan->channel),
+ val);
+ default:
+ return -EINVAL;
+ }
+}
+
+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 iio_dev *indio_dev;
+ struct ad5706r_state *st;
+ int ret;
+
+ indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
+ if (!indio_dev)
+ return -ENOMEM;
+
+ st = iio_priv(indio_dev);
+ st->spi = spi;
+
+ ret = devm_mutex_init(&spi->dev, &st->lock);
+ if (ret)
+ return ret;
+
+ 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(&spi->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", 0 },
+ { }
+};
+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@xxxxxxxxxx>");
+MODULE_DESCRIPTION("AD5706R 16-bit Current Output DAC driver");
+MODULE_LICENSE("GPL");
--
2.34.1