Re: [PATCH 1/3] staging: iio: adc: ad7280a: split ad7280_channel_init() to more functions

[Jonathan Cameron <jic23@kernel.org>]

On Sun,  2 Dec 2018 12:58:28 +0100
Slawomir Stepien <sst@poczta.fm> wrote:

> The ad7280_channel_init function has been split into more specific
> functions to increase the code readability.
> 
> Signed-off-by: Slawomir Stepien <sst@poczta.fm>
Hi Slawomir,

A few comments inline.  I agree with the basic idea, but suggest
a slight different balance in where things are handled.

Jonathan

> ---
>  drivers/staging/iio/adc/ad7280a.c | 119 +++++++++++++++++++-----------
>  1 file changed, 77 insertions(+), 42 deletions(-)
> 
> diff --git a/drivers/staging/iio/adc/ad7280a.c b/drivers/staging/iio/adc/ad7280a.c
> index 7a0ba26f9fd9..a6b1bdd9f372 100644
> --- a/drivers/staging/iio/adc/ad7280a.c
> +++ b/drivers/staging/iio/adc/ad7280a.c
> @@ -496,6 +496,75 @@ static const struct attribute_group ad7280_attrs_group = {
>  	.attrs = ad7280_attributes,
>  };
>  
> +static void ad7280_voltage_channel_init(struct ad7280_state *st, int cnt,
> +					int dev, int ch)
> +{
> +	struct iio_chan_spec *chan = &st->channels[cnt];

Pass the chan spec in here instead of the _state structure.
It will give cleaner code and better visibility on the scope of
this function where it is called.

> +
> +	chan->type = IIO_VOLTAGE;
> +	chan->differential = 1;
> +	chan->channel = (dev * 6) + ch;

This offset does seem more than a little random buried away in this function.
I would pass it in explicitly as a parameter so that the we have all the
channel number manipulations visible in one place.

> +	chan->channel2 = chan->channel + 1;
> +}
> +
> +static void ad7280_temp_channel_init(struct ad7280_state *st, int cnt, int dev,
> +				     int ch)
> +{
> +	struct iio_chan_spec *chan = &st->channels[cnt];
> +
> +	chan->type = IIO_TEMP;
> +	chan->channel = (dev * 6) + ch - 6;
This one is even more obscure when found in here. Pass it in as an additional parameter.
> +}
> +
> +static void ad7280_common_fields_init(struct ad7280_state *st, int cnt, int dev,
> +				      int ch)

It's not really the common fields given the voltage version is different.
Perhaps there is a better name for this function?


> +{
> +	struct iio_chan_spec *chan = &st->channels[cnt];
> +
> +	chan->indexed = 1;
> +	chan->info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
> +	chan->info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE);
> +	chan->address = ad7280a_devaddr(dev) << 8 | ch;
> +	chan->scan_index = cnt;
> +	chan->scan_type.sign = 'u';
> +	chan->scan_type.realbits = 12;
> +	chan->scan_type.storagebits = 32;
> +	chan->scan_type.shift = 0;

I doubt there is any need to set shift and 0 is the obvious default
so no 'documentation' benefit in doing it here.

> +}
> +
> +static void ad7280_all_voltage_channel_init(struct ad7280_state *st, int cnt,
> +					    int dev)
Total voltage perhaps rather than 'all'? 
> +{
> +	struct iio_chan_spec *chan = &st->channels[cnt];
> +
> +	chan->type = IIO_VOLTAGE;
> +	chan->differential = 1;
> +	chan->channel = 0;
> +	chan->channel2 = dev * 6;
> +	chan->address = AD7280A_ALL_CELLS;
> +	chan->indexed = 1;
> +	chan->info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
> +	chan->info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE);
> +	chan->scan_index = cnt;
> +	chan->scan_type.sign = 'u';
> +	chan->scan_type.realbits = 32;
> +	chan->scan_type.storagebits = 32;
> +	chan->scan_type.shift = 0;
> +}
> +
> +static void ad7280_timestamp_channel_init(struct ad7280_state *st, int cnt)
> +{
> +	struct iio_chan_spec *chan = &st->channels[cnt];
> +
> +	chan->type = IIO_TIMESTAMP;
> +	chan->channel = -1;
> +	chan->scan_index = cnt;
> +	chan->scan_type.sign = 's';
> +	chan->scan_type.realbits = 64;
> +	chan->scan_type.storagebits = 64;
> +	chan->scan_type.shift = 0;
> +}
> +
>  static int ad7280_channel_init(struct ad7280_state *st)
>  {
>  	int dev, ch, cnt;
> @@ -508,51 +577,17 @@ static int ad7280_channel_init(struct ad7280_state *st)
>  	for (dev = 0, cnt = 0; dev <= st->slave_num; dev++)
>  		for (ch = AD7280A_CELL_VOLTAGE_1; ch <= AD7280A_AUX_ADC_6;
>  			ch++, cnt++) {
> -			if (ch < AD7280A_AUX_ADC_1) {
> -				st->channels[cnt].type = IIO_VOLTAGE;
> -				st->channels[cnt].differential = 1;
> -				st->channels[cnt].channel = (dev * 6) + ch;
> -				st->channels[cnt].channel2 =
> -					st->channels[cnt].channel + 1;
> -			} else {
> -				st->channels[cnt].type = IIO_TEMP;
> -				st->channels[cnt].channel = (dev * 6) + ch - 6;
> -			}
> -			st->channels[cnt].indexed = 1;
> -			st->channels[cnt].info_mask_separate =
> -				BIT(IIO_CHAN_INFO_RAW);
> -			st->channels[cnt].info_mask_shared_by_type =
> -				BIT(IIO_CHAN_INFO_SCALE);
> -			st->channels[cnt].address =
> -				ad7280a_devaddr(dev) << 8 | ch;
> -			st->channels[cnt].scan_index = cnt;
> -			st->channels[cnt].scan_type.sign = 'u';
> -			st->channels[cnt].scan_type.realbits = 12;
> -			st->channels[cnt].scan_type.storagebits = 32;
> -			st->channels[cnt].scan_type.shift = 0;
> +			if (ch < AD7280A_AUX_ADC_1)
> +				ad7280_voltage_channel_init(st, cnt, dev, ch);
> +			else
> +				ad7280_temp_channel_init(st, cnt, dev, ch);
> +
> +			ad7280_common_fields_init(st, cnt, dev, ch);
>  		}
>  
> -	st->channels[cnt].type = IIO_VOLTAGE;
> -	st->channels[cnt].differential = 1;
> -	st->channels[cnt].channel = 0;
> -	st->channels[cnt].channel2 = dev * 6;
> -	st->channels[cnt].address = AD7280A_ALL_CELLS;
> -	st->channels[cnt].indexed = 1;
> -	st->channels[cnt].info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
> -	st->channels[cnt].info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE);
> -	st->channels[cnt].scan_index = cnt;
> -	st->channels[cnt].scan_type.sign = 'u';
> -	st->channels[cnt].scan_type.realbits = 32;
> -	st->channels[cnt].scan_type.storagebits = 32;
> -	st->channels[cnt].scan_type.shift = 0;
> +	ad7280_all_voltage_channel_init(st, cnt, dev);
>  	cnt++;
> -	st->channels[cnt].type = IIO_TIMESTAMP;
> -	st->channels[cnt].channel = -1;
> -	st->channels[cnt].scan_index = cnt;
> -	st->channels[cnt].scan_type.sign = 's';
> -	st->channels[cnt].scan_type.realbits = 64;
> -	st->channels[cnt].scan_type.storagebits = 64;
> -	st->channels[cnt].scan_type.shift = 0;
> +	ad7280_timestamp_channel_init(st, cnt);
>  
>  	return cnt + 1;
>  }