linux-kernel - Re: [PATCH v3 08/27] staging: iio: resolver: ad2s1210: implement IIO_CHAN_INFO

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Date:   Sat, 30 Sep 2023 15:43:15 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     David Lechner <dlechner@...libre.com>
Cc:     linux-iio@...r.kernel.org, devicetree@...r.kernel.org,
        linux-staging@...ts.linux.dev,
        David Lechner <david@...hnology.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Michael Hennerich <Michael.Hennerich@...log.com>,
        Nuno Sá <nuno.sa@...log.com>,
        Axel Haslam <ahaslam@...libre.com>,
        Philip Molloy <pmolloy@...libre.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 08/27] staging: iio: resolver: ad2s1210: implement
 IIO_CHAN_INFO_SCALE

On Fri, 29 Sep 2023 12:23:13 -0500
David Lechner <dlechner@...libre.com> wrote:

> From: David Lechner <david@...hnology.com>
> 
> From: David Lechner <dlechner@...libre.com>
> 
> This adds an implementation of IIO_CHAN_INFO_SCALE to the ad2s1210
> resolver driver. This allows userspace to get the scale factor for the
> raw values.
> 
> Signed-off-by: David Lechner <dlechner@...libre.com>
Applied

Thanks,

> ---
> 
> v3 changes:
> * Split ad2s1210_read_raw() into two functions to reduce complexity.
> * Use early return instead of break in switch statements.
> 
>  drivers/staging/iio/resolver/ad2s1210.c | 53 ++++++++++++++++++++++++++++-----
>  1 file changed, 45 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/staging/iio/resolver/ad2s1210.c b/drivers/staging/iio/resolver/ad2s1210.c
> index f9774dff2df4..a710598a64f0 100644
> --- a/drivers/staging/iio/resolver/ad2s1210.c
> +++ b/drivers/staging/iio/resolver/ad2s1210.c
> @@ -461,13 +461,10 @@ static ssize_t ad2s1210_store_reg(struct device *dev,
>  	return ret < 0 ? ret : len;
>  }
>  
> -static int ad2s1210_read_raw(struct iio_dev *indio_dev,
> -			     struct iio_chan_spec const *chan,
> -			     int *val,
> -			     int *val2,
> -			     long m)
> +static int ad2s1210_single_conversion(struct ad2s1210_state *st,
> +				      struct iio_chan_spec const *chan,
> +				      int *val)
>  {
> -	struct ad2s1210_state *st = iio_priv(indio_dev);
>  	int ret = 0;
>  
>  	mutex_lock(&st->lock);
> @@ -514,6 +511,44 @@ static int ad2s1210_read_raw(struct iio_dev *indio_dev,
>  	return ret;
>  }
>  
> +static const int ad2s1210_velocity_scale[] = {
> +	17089132, /* 8.192MHz / (2*pi * 2500 / 2^15) */
> +	42722830, /* 8.192MHz / (2*pi * 1000 / 2^15) */
> +	85445659, /* 8.192MHz / (2*pi * 500 / 2^15) */
> +	341782638, /* 8.192MHz / (2*pi * 125 / 2^15) */
> +};
> +
> +static int ad2s1210_read_raw(struct iio_dev *indio_dev,
> +			     struct iio_chan_spec const *chan,
> +			     int *val,
> +			     int *val2,
> +			     long mask)
> +{
> +	struct ad2s1210_state *st = iio_priv(indio_dev);
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		return ad2s1210_single_conversion(st, chan, val);
> +	case IIO_CHAN_INFO_SCALE:
> +		switch (chan->type) {
> +		case IIO_ANGL:
> +			/* approx 0.3 arc min converted to radians */
> +			*val = 0;
> +			*val2 = 95874;
> +			return IIO_VAL_INT_PLUS_NANO;
> +		case IIO_ANGL_VEL:
> +			*val = st->fclkin;
> +			*val2 = ad2s1210_velocity_scale[st->resolution];
> +			return IIO_VAL_FRACTIONAL;
> +		default:
> +			return -EINVAL;
> +		}
> +
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
>  static IIO_DEVICE_ATTR(fclkin, 0644,
>  		       ad2s1210_show_fclkin, ad2s1210_store_fclkin, 0);
>  static IIO_DEVICE_ATTR(fexcit, 0644,
> @@ -552,12 +587,14 @@ static const struct iio_chan_spec ad2s1210_channels[] = {
>  		.type = IIO_ANGL,
>  		.indexed = 1,
>  		.channel = 0,
> -		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> +				      BIT(IIO_CHAN_INFO_SCALE),
>  	}, {
>  		.type = IIO_ANGL_VEL,
>  		.indexed = 1,
>  		.channel = 0,
> -		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> +				      BIT(IIO_CHAN_INFO_SCALE),
>  	}
>  };
>  
>