linux-kernel - Re: [PATCH v3 2/3] staging: iio: ad9832: Refactor powerdown control

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Message-ID: <CAKUZ0zKXg4KLpHPLtpkywPLp8+xxwAMSpNAgUmP34pfVZDv7Aw@mail.gmail.com>
Date: Thu, 24 Apr 2025 18:25:51 -0400
From: Gabriel Shahrouzi <gshahrouzi@...il.com>
To: Jonathan Cameron <jic23@...nel.org>
Cc: gregkh@...uxfoundation.org, lars@...afoo.de, linux-iio@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-staging@...ts.linux.dev, 
	Michael.Hennerich@...log.com, skhan@...uxfoundation.org, 
	linux-kernel-mentees@...ts.linux.dev
Subject: Re: [PATCH v3 2/3] staging: iio: ad9832: Refactor powerdown control

On Mon, Apr 21, 2025 at 7:37 AM Jonathan Cameron <jic23@...nel.org> wrote:
>
> On Sun, 20 Apr 2025 13:54:18 -0400
> Gabriel Shahrouzi <gshahrouzi@...il.com> wrote:
>
> > Replace custom implementation with out_altvoltage_powerdown ABI. The
> > attribute's logic is inverted (1 now enables powerdown) to match the
> > standard. Modernize driver by using the standard IIO interface.
> >
> > Signed-off-by: Gabriel Shahrouzi <gshahrouzi@...il.com>
> > ---
> >  drivers/staging/iio/frequency/ad9832.c | 44 ++++++++++++++++++--------
> >  1 file changed, 30 insertions(+), 14 deletions(-)
> >
> > diff --git a/drivers/staging/iio/frequency/ad9832.c b/drivers/staging/iio/frequency/ad9832.c
> > index 0872ff4ec4896..a8fc20379efed 100644
> > --- a/drivers/staging/iio/frequency/ad9832.c
> > +++ b/drivers/staging/iio/frequency/ad9832.c
> > @@ -167,6 +167,34 @@ static int ad9832_write_phase(struct ad9832_state *st,
> >       return spi_sync(st->spi, &st->phase_msg);
> >  }
> >
> > +static ssize_t ad9832_write_powerdown(struct device *dev, struct device_attribute *attr,
> > +                                   const char *buf, size_t len)
> > +{
> > +     struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> > +     struct ad9832_state *st = iio_priv(indio_dev);
> > +     int ret;
> > +     unsigned long val;
> > +
> > +     ret = kstrtoul(buf, 10, &val);
> > +     if (ret)
> > +             goto error_ret;
> > +
> > +     mutex_lock(&st->lock);
>
> Look at how guard(mutex)(&st->lock);
> can be used in this driver to simplify things considerably.
Noted, added into new version.
> May make sense to do that before introducing this new code.
Not sure whether to have made it its own patch or not. I grouped it
together with the new code since it also uses locking.
>
> > +     if (val)
> > +             st->ctrl_src |= AD9832_SLEEP;
> > +     else
> > +             st->ctrl_src &= ~(AD9832_RESET | AD9832_SLEEP |
> > +                              AD9832_CLR);
> > +
> > +     st->data = cpu_to_be16((AD9832_CMD_SLEEPRESCLR << CMD_SHIFT) |
> > +                             st->ctrl_src);
> > +     ret = spi_sync(st->spi, &st->msg);
> > +     mutex_unlock(&st->lock);
> > +
> > +error_ret:
> > +     return ret ? ret : len;
> > +}
> > +
> >  static ssize_t ad9832_write(struct device *dev, struct device_attribute *attr,
> >                           const char *buf, size_t len)
> >  {
> > @@ -227,17 +255,6 @@ static ssize_t ad9832_write(struct device *dev, struct device_attribute *attr,
> >                                       st->ctrl_fp);
> >               ret = spi_sync(st->spi, &st->msg);
> >               break;
> > -     case AD9832_OUTPUT_EN:
> > -             if (val)
> > -                     st->ctrl_src &= ~(AD9832_RESET | AD9832_SLEEP |
> > -                                     AD9832_CLR);
> > -             else
> > -                     st->ctrl_src |= AD9832_SLEEP;
> > -
> > -             st->data = cpu_to_be16((AD9832_CMD_SLEEPRESCLR << CMD_SHIFT) |
> > -                                     st->ctrl_src);
> > -             ret = spi_sync(st->spi, &st->msg);
> > -             break;
> >       default:
> >               ret = -ENODEV;
> >       }
> > @@ -266,8 +283,7 @@ static IIO_CONST_ATTR_PHASE_SCALE(0, "0.0015339808"); /* 2PI/2^12 rad*/
> >
> >  static IIO_DEV_ATTR_PINCONTROL_EN(0, 0200, NULL,
> >                               ad9832_write, AD9832_PINCTRL_EN);
> > -static IIO_DEV_ATTR_OUT_ENABLE(0, 0200, NULL,
> > -                             ad9832_write, AD9832_OUTPUT_EN);
> > +static IIO_DEVICE_ATTR(out_altvoltage_powerdown, 0200, NULL, ad9832_write_powerdown, 0);
>
> Take a look at the use of extended attributes used for this like we see
> in ad5064.c
> That will need an actual channel though so is a more significant rework.
Got it.
>
> >
> >  static struct attribute *ad9832_attributes[] = {
> >       &iio_dev_attr_out_altvoltage0_frequency0.dev_attr.attr,
> > @@ -281,7 +297,7 @@ static struct attribute *ad9832_attributes[] = {
> >       &iio_dev_attr_out_altvoltage0_pincontrol_en.dev_attr.attr,
> >       &iio_dev_attr_out_altvoltage0_frequencysymbol.dev_attr.attr,
> >       &iio_dev_attr_out_altvoltage0_phasesymbol.dev_attr.attr,
> > -     &iio_dev_attr_out_altvoltage0_out_enable.dev_attr.attr,
> > +     &iio_dev_attr_out_altvoltage_powerdown.dev_attr.attr,
> >       NULL,
> >  };
> >
>