[PATCH 21/22] iio: dac: ad5686: add triggered buffer support

Rodrigo Alencar via B4 Relay
2026-04-22T14:46:25Z

From: Rodrigo Alencar <rodrigo.alencar@analog.com>

Trigger handler is implemented by leveraging the LDAC gpio when it is
available. Multiple channel writes can be flushed at once with the sync()
operation.

Signed-off-by: Rodrigo Alencar <rodrigo.alencar@analog.com>
---
drivers/iio/dac/Kconfig | 2 ++
drivers/iio/dac/ad5686.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 64 insertions(+)

diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
index 8ef4a87d6d6a..bb4d3bdabef2 100644
--- a/drivers/iio/dac/Kconfig
+++ b/drivers/iio/dac/Kconfig
@@ -229,6 +229,8 @@ config LTC2688

config AD5686
tristate
+ select IIO_BUFFER
+ select IIO_TRIGGERED_BUFFER

config AD5686_SPI
tristate "Analog Devices AD5686 and similar multi-channel DACs (SPI)"
diff --git a/drivers/iio/dac/ad5686.c b/drivers/iio/dac/ad5686.c
index a065c614c874..bec951afe8d0 100644
--- a/drivers/iio/dac/ad5686.c
+++ b/drivers/iio/dac/ad5686.c
@@ -16,6 +16,11 @@
#include <linux/sysfs.h>
#include <linux/wordpart.h>

+#include <linux/iio/buffer.h>
+#include <linux/iio/trigger.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+
#include "ad5686.h"

static const char * const ad5686_powerdown_modes[] = {
@@ -227,6 +232,7 @@ static const struct iio_chan_spec_ext_info ad5686_ext_info[] = {
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),\
.address = addr, \
+ .scan_index = chan, \
.scan_type = { \
.sign = 'u', \
.realbits = (bits), \
@@ -506,6 +512,55 @@ const struct ad5686_chip_info ad5679r_chip_info = {
};
EXPORT_SYMBOL_NS_GPL(ad5679r_chip_info, "IIO_AD5686");

+static irqreturn_t ad5686_trigger_handler(int irq, void *p)
+{
+ struct iio_poll_func *pf = p;
+ struct iio_dev *indio_dev = pf->indio_dev;
+ struct iio_buffer *buffer = indio_dev->buffer;
+ struct ad5686_state *st = iio_priv(indio_dev);
+ const struct iio_chan_spec *chan;
+ u16 val[AD5686_MAX_CHANNELS];
+ int ret, ch, i = 0;
+ bool async_update;
+ u8 cmd;
+
+ ret = iio_pop_from_buffer(buffer, val);
+ if (ret)
+ goto out;
+
+ mutex_lock(&st->lock);
+
+ async_update = st->ldac_gpio && bitmap_weight(indio_dev->active_scan_mask,
+ iio_get_masklength(indio_dev)) > 1;
+ if (async_update) {
+ /* use ldac to update all channels simultaneously */
+ cmd = AD5686_CMD_WRITE_INPUT_N;
+ gpiod_set_value_cansleep(st->ldac_gpio, 0);
+ } else {
+ cmd = AD5686_CMD_WRITE_INPUT_N_UPDATE_N;
+ }
+
+ iio_for_each_active_channel(indio_dev, ch) {
+ chan = &indio_dev->channels[ch];
+ ret = st->ops->write(st, cmd, chan->address,
+ val[i++] << chan->scan_type.shift);
+ if (ret)
+ break;
+ }
+
+ if (!ret && st->ops->sync)
+ ret = st->ops->sync(st); /* flush all pending transfers */
+
+ if (async_update)
+ gpiod_set_value_cansleep(st->ldac_gpio, 1);
+
+ mutex_unlock(&st->lock);
+out:
+ iio_trigger_notify_done(indio_dev->trig);
+
+ return IRQ_HANDLED;
+}
+
int ad5686_probe(struct device *dev,
const struct ad5686_chip_info *chip_info,
const char *name, const struct ad5686_bus_ops *ops,
@@ -599,6 +654,13 @@ int ad5686_probe(struct device *dev,
return -EINVAL;
}

+ ret = devm_iio_triggered_buffer_setup_ext(dev, indio_dev, NULL,
+ &ad5686_trigger_handler,
+ IIO_BUFFER_DIRECTION_OUT,
+ NULL, NULL);
+ if (ret)
+ return ret;
+
return devm_iio_device_register(dev, indio_dev);
}
EXPORT_SYMBOL_NS_GPL(ad5686_probe, "IIO_AD5686");

--
2.43.0