Re: [PATCH v7 6/7] iio: dac: ad5686: add triggered buffer support

[David Lechner]

On 7/10/26 6:20 AM, Rodrigo Alencar via B4 Relay wrote:
> From: Rodrigo Alencar <rodrigo.alencar@xxxxxxxxxx>
> 
> Implement trigger handler by leveraging the LDAC gpio to update all DAC
> channels at once when it is available. Also, the multiple channel writes
> can be flushed at once with the sync() operation.
> 
> Signed-off-by: Rodrigo Alencar <rodrigo.alencar@xxxxxxxxxx>
> ---
>  drivers/iio/dac/Kconfig  |  2 ++
>  drivers/iio/dac/ad5686.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 68 insertions(+)
> 
> diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
> index 17529509da9d..d6d560c09e25 100644
> --- a/drivers/iio/dac/Kconfig
> +++ b/drivers/iio/dac/Kconfig
> @@ -243,6 +243,8 @@ 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 df32f46db81e..eeeff5c6cf38 100644
> --- a/drivers/iio/dac/ad5686.c
> +++ b/drivers/iio/dac/ad5686.c
> @@ -21,7 +21,11 @@
>  #include <linux/sysfs.h>
>  #include <linux/wordpart.h>
>  
> +#include <linux/iio/buffer.h>
>  #include <linux/iio/iio.h>
> +#include <linux/iio/trigger.h>
> +#include <linux/iio/trigger_consumer.h>
> +#include <linux/iio/triggered_buffer.h>
>  
>  #include "ad5686.h"
>  
> @@ -243,6 +247,7 @@ 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),			\
> @@ -467,6 +472,60 @@ const struct ad5686_chip_info ad5679r_chip_info = {
>  };
>  EXPORT_SYMBOL_NS_GPL(ad5679r_chip_info, "IIO_AD5686");
>  
> +static void do_ad5686_trigger_handler(struct iio_dev *indio_dev)
> +{
> +	struct iio_buffer *buffer = indio_dev->buffer;

Only used once and doesn't save a line wrap, so no need for a local variable.

> +	struct ad5686_state *st = iio_priv(indio_dev);
> +	u16 val[AD5686_MAX_CHANNELS] = { };
> +	unsigned int scan_count, ch, i;
> +	bool async_update;
> +	u8 cmd;
> +
> +	if (iio_pop_from_buffer(buffer, val))
> +		return;
> +
> +	guard(mutex)(&st->lock);
> +
> +	scan_count = bitmap_weight(indio_dev->active_scan_mask,
> +				   iio_get_masklength(indio_dev));
> +	async_update = st->ldac_gpio && scan_count > 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;
> +	}
> +
> +	i = 0;
> +	iio_for_each_active_channel(indio_dev, ch) {
> +		if (st->ops->write(st, cmd, indio_dev->channels[ch].address, val[i++]))
> +			break;
> +	}
> +
> +	/*
> +	 * If sync() is available, it is called here regardless of write
> +	 * failure to allow bus implementation to reset. In that case, partial
> +	 * writes are unlikely as the write operations would just queue up
> +	 * the transfers.
> +	 */
> +	if (st->ops->sync)
> +		st->ops->sync(st);
> +
> +	if (async_update)
> +		gpiod_set_value_cansleep(st->ldac_gpio, 1);
> +}
> +