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

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Message-ID: <20250421123728.1564039d@jic23-huawei>
Date: Mon, 21 Apr 2025 12:37:28 +0100
From: Jonathan Cameron <jic23@...nel.org>
To: Gabriel Shahrouzi <gshahrouzi@...il.com>
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 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.
May make sense to do that before introducing this new code.

> +	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.

>  
>  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,
>  };
>