Re: [PATCH v5 6/6] drivers:iio:dac:ad5766.c: Add trigger buffer

From: Alexandru Ardelean
Date: Fri Sep 17 2021 - 04:09:15 EST


On Fri, Sep 17, 2021 at 9:11 AM Mihail Chindris
<mihail.chindris@xxxxxxxxxx> wrote:
>
> This chip is able to generate waveform and using an
> with the output trigger buffer will be easy to generate one.
>

This turned out to look quite neat.
Some minor notes inline.
Nothing major.
But other than that:

Reviewed-by: Alexandru Ardelean <ardeleanalex@xxxxxxxxx>

> Signed-off-by: Mihail Chindris <mihail.chindris@xxxxxxxxxx>
> ---
> drivers/iio/dac/ad5766.c | 36 ++++++++++++++++++++++++++++++++++++
> 1 file changed, 36 insertions(+)
>
> diff --git a/drivers/iio/dac/ad5766.c b/drivers/iio/dac/ad5766.c
> index dafda84fdea3..71491e6d466e 100644
> --- a/drivers/iio/dac/ad5766.c
> +++ b/drivers/iio/dac/ad5766.c
> @@ -5,10 +5,13 @@
> * Copyright 2019-2020 Analog Devices Inc.
> */
> #include <linux/bitfield.h>
> +#include <linux/bitops.h>
> #include <linux/delay.h>
> #include <linux/device.h>
> #include <linux/gpio/consumer.h>
> #include <linux/iio/iio.h>
> +#include <linux/iio/triggered_buffer.h>
> +#include <linux/iio/trigger_consumer.h>
> #include <linux/module.h>
> #include <linux/spi/spi.h>
> #include <asm/unaligned.h>
> @@ -41,6 +44,7 @@
> #define AD5766_CMD_DITHER_SCALE_2 0xD0
>
> #define AD5766_FULL_RESET_CODE 0x1234
> +#define AD5766_NUM_CH 16
>
> enum ad5766_type {
> ID_AD5766,
> @@ -455,6 +459,7 @@ static const struct iio_chan_spec_ext_info ad5766_ext_info[] = {
> .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
> .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_OFFSET) | \
> BIT(IIO_CHAN_INFO_SCALE), \
> + .scan_index = (_chan), \
> .scan_type = { \
> .sign = 'u', \
> .realbits = (_bits), \
> @@ -576,6 +581,28 @@ static int ad5766_default_setup(struct ad5766_state *st)
> return __ad5766_spi_write(st, AD5766_CMD_SPAN_REG, st->crt_range);
> }
>
> +static irqreturn_t ad5766_trigger_handler(int irq, void *p)
> +{
> + struct iio_poll_func *pf = p;
> + struct iio_dev *indio_dev = pf->indio_dev;
> + struct iio_buffer *buf = indio_dev->buffer;

Purely stylistic.
I would keep the variable name as "struct iio_buffer *bufffer".
Reason is: when you start to grep the kernel-code, `buf` tends to
refer to simple/small buffers (like buf[4], or buf[16]).
And when wanting to do some multiple-changes, grepping easier is useful.

> + int ret, ch, i;
> + u16 data[AD5766_NUM_CH];
> +
> + ret = iio_pop_from_buffer(buf, (u8 *)data);

Does the compiler complain if this (u8 *) cast is removed?
Because it doesn't look like this is needed or that it would do
anything as the argument of data is (void *).

> + if (ret)
> + goto done;
> +
> + i = 0;
> + for_each_set_bit(ch, indio_dev->active_scan_mask, AD5766_NUM_CH - 1)
> + ad5766_write(indio_dev, ch, le16_to_cpu(data[i++]));
> +
> +done:
> + iio_trigger_notify_done(indio_dev->trig);
> +
> + return IRQ_HANDLED;
> +}
> +
> static int ad5766_probe(struct spi_device *spi)
> {
> enum ad5766_type type;
> @@ -609,6 +636,15 @@ static int ad5766_probe(struct spi_device *spi)
> if (ret)
> return ret;
>
> + /* Configure trigger buffer */
> + ret = devm_iio_triggered_buffer_setup_ext(&spi->dev, indio_dev, NULL,
> + ad5766_trigger_handler,
> + IIO_BUFFER_DIRECTION_OUT,
> + NULL,
> + NULL);
> + if (ret)
> + return ret;
> +
> return devm_iio_device_register(&spi->dev, indio_dev);
> }
>
> --
> 2.27.0
>