Re: [PATCH v3 2/3] iio: adc: ad7192: Improve f_order computation

[Jonathan Cameron <jic23@kernel.org>]

On Mon, 25 Sep 2023 00:51:47 +0300
alisadariana@gmail.com wrote:

> From: Alisa-Dariana Roman <alisa.roman@analog.com>
> 
> Instead of using the f_order member of ad7192_state, a function that
> computes the f_order coefficient makes more sense. This coefficient is a
> function of the sinc filter and chop filter states.
> 
> Remove f_order member of ad7192_state structure. Instead use
> ad7192_compute_f_order function to compute the f_order coefficient
> according to the sinc filter and chop filter states passed as
> parameters.
> 
> Add ad7192_get_f_order function that returns the current f_order
> coefficient of the device.
> 
> Add ad7192_compute_f_adc function that computes the f_adc value
> according to the sinc filter and chop filter states passed as
> parameters.
> 
> Add ad7192_get_f_adc function that returns the current f_adc value of
> the device.
> 
> Signed-off-by: Alisa-Dariana Roman <alisa.roman@analog.com>
Applied to the togreg branch of iio.git and pushed out as testing
for 0-day to see if it can find anything we missed.

Thanks,

Jonathan

> ---
>  drivers/iio/adc/ad7192.c | 62 +++++++++++++++++++++++++++++-----------
>  1 file changed, 46 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/iio/adc/ad7192.c b/drivers/iio/adc/ad7192.c
> index d693f2ce8a20..0f9d33002d35 100644
> --- a/drivers/iio/adc/ad7192.c
> +++ b/drivers/iio/adc/ad7192.c
> @@ -179,7 +179,6 @@ struct ad7192_state {
>  	struct clk			*mclk;
>  	u16				int_vref_mv;
>  	u32				fclk;
> -	u32				f_order;
>  	u32				mode;
>  	u32				conf;
>  	u32				scale_avail[8][2];
> @@ -419,7 +418,6 @@ static int ad7192_setup(struct iio_dev *indio_dev, struct device_node *np)
>  		st->conf |= AD7192_CONF_REFSEL;
>  
>  	st->conf &= ~AD7192_CONF_CHOP;
> -	st->f_order = AD7192_NO_SYNC_FILTER;
>  
>  	buf_en = of_property_read_bool(np, "adi,buffer-enable");
>  	if (buf_en)
> @@ -530,22 +528,60 @@ static ssize_t ad7192_set(struct device *dev,
>  	return ret ? ret : len;
>  }
>  
> +static int ad7192_compute_f_order(bool sinc3_en, bool chop_en)
> +{
> +	if (!chop_en)
> +		return 1;
> +
> +	if (sinc3_en)
> +		return AD7192_SYNC3_FILTER;
> +
> +	return AD7192_SYNC4_FILTER;
> +}
> +
> +static int ad7192_get_f_order(struct ad7192_state *st)
> +{
> +	bool sinc3_en, chop_en;
> +
> +	sinc3_en = FIELD_GET(AD7192_MODE_SINC3, st->mode);
> +	chop_en = FIELD_GET(AD7192_CONF_CHOP, st->conf);
> +
> +	return ad7192_compute_f_order(sinc3_en, chop_en);
> +}
> +
> +static int ad7192_compute_f_adc(struct ad7192_state *st, bool sinc3_en,
> +				bool chop_en)
> +{
> +	unsigned int f_order = ad7192_compute_f_order(sinc3_en, chop_en);
> +
> +	return DIV_ROUND_CLOSEST(st->fclk,
> +				 f_order * FIELD_GET(AD7192_MODE_RATE_MASK, st->mode));
> +}
> +
> +static int ad7192_get_f_adc(struct ad7192_state *st)
> +{
> +	unsigned int f_order = ad7192_get_f_order(st);
> +
> +	return DIV_ROUND_CLOSEST(st->fclk,
> +				 f_order * FIELD_GET(AD7192_MODE_RATE_MASK, st->mode));
> +}
> +
>  static void ad7192_get_available_filter_freq(struct ad7192_state *st,
>  						    int *freq)
>  {
>  	unsigned int fadc;
>  
>  	/* Formulas for filter at page 25 of the datasheet */
> -	fadc = DIV_ROUND_CLOSEST(st->fclk,
> -				 AD7192_SYNC4_FILTER * FIELD_GET(AD7192_MODE_RATE_MASK, st->mode));
> +	fadc = ad7192_compute_f_adc(st, false, true);
>  	freq[0] = DIV_ROUND_CLOSEST(fadc * 240, 1024);
>  
> -	fadc = DIV_ROUND_CLOSEST(st->fclk,
> -				 AD7192_SYNC3_FILTER * FIELD_GET(AD7192_MODE_RATE_MASK, st->mode));
> +	fadc = ad7192_compute_f_adc(st, true, true);
>  	freq[1] = DIV_ROUND_CLOSEST(fadc * 240, 1024);
>  
> -	fadc = DIV_ROUND_CLOSEST(st->fclk, FIELD_GET(AD7192_MODE_RATE_MASK, st->mode));
> +	fadc = ad7192_compute_f_adc(st, false, false);
>  	freq[2] = DIV_ROUND_CLOSEST(fadc * 230, 1024);
> +
> +	fadc = ad7192_compute_f_adc(st, true, false);
>  	freq[3] = DIV_ROUND_CLOSEST(fadc * 272, 1024);
>  }
>  
> @@ -628,25 +664,21 @@ static int ad7192_set_3db_filter_freq(struct ad7192_state *st,
>  
>  	switch (idx) {
>  	case 0:
> -		st->f_order = AD7192_SYNC4_FILTER;
>  		st->mode &= ~AD7192_MODE_SINC3;
>  
>  		st->conf |= AD7192_CONF_CHOP;
>  		break;
>  	case 1:
> -		st->f_order = AD7192_SYNC3_FILTER;
>  		st->mode |= AD7192_MODE_SINC3;
>  
>  		st->conf |= AD7192_CONF_CHOP;
>  		break;
>  	case 2:
> -		st->f_order = AD7192_NO_SYNC_FILTER;
>  		st->mode &= ~AD7192_MODE_SINC3;
>  
>  		st->conf &= ~AD7192_CONF_CHOP;
>  		break;
>  	case 3:
> -		st->f_order = AD7192_NO_SYNC_FILTER;
>  		st->mode |= AD7192_MODE_SINC3;
>  
>  		st->conf &= ~AD7192_CONF_CHOP;
> @@ -664,8 +696,7 @@ static int ad7192_get_3db_filter_freq(struct ad7192_state *st)
>  {
>  	unsigned int fadc;
>  
> -	fadc = DIV_ROUND_CLOSEST(st->fclk,
> -				 st->f_order * FIELD_GET(AD7192_MODE_RATE_MASK, st->mode));
> +	fadc = ad7192_get_f_adc(st);
>  
>  	if (FIELD_GET(AD7192_CONF_CHOP, st->conf))
>  		return DIV_ROUND_CLOSEST(fadc * 240, 1024);
> @@ -713,8 +744,7 @@ static int ad7192_read_raw(struct iio_dev *indio_dev,
>  			*val -= 273 * ad7192_get_temp_scale(unipolar);
>  		return IIO_VAL_INT;
>  	case IIO_CHAN_INFO_SAMP_FREQ:
> -		*val = st->fclk /
> -			(st->f_order * 1024 * FIELD_GET(AD7192_MODE_RATE_MASK, st->mode));
> +		*val = DIV_ROUND_CLOSEST(ad7192_get_f_adc(st), 1024);
>  		return IIO_VAL_INT;
>  	case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
>  		*val = ad7192_get_3db_filter_freq(st);
> @@ -764,7 +794,7 @@ static int ad7192_write_raw(struct iio_dev *indio_dev,
>  			break;
>  		}
>  
> -		div = st->fclk / (val * st->f_order * 1024);
> +		div = st->fclk / (val * ad7192_get_f_order(st) * 1024);
>  		if (div < 1 || div > 1023) {
>  			ret = -EINVAL;
>  			break;