Re: [PATCH 1/2] staging: iio: frequency: ad9834: Move frequency to standard iio types

[Jonathan Cameron <jic23@kernel.org>]

On Wed, 6 Feb 2019 14:05:41 +0200
Beniamin Bia <biabeniamin@outlook.com> wrote:

> Frequency attribute is added with a standard type from iio framework
> instead of custom attribute. This is a small step towards removing any
> unnecessary custom attribute.
> 
> Signed-off-by: Beniamin Bia <beniamin.bia@analog.com>
> ---
>  drivers/staging/iio/frequency/ad9834.c | 97 +++++++++++++++++++++-----
>  1 file changed, 80 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/staging/iio/frequency/ad9834.c b/drivers/staging/iio/frequency/ad9834.c
> index f036f75d1f22..370e8263899e 100644
> --- a/drivers/staging/iio/frequency/ad9834.c
> +++ b/drivers/staging/iio/frequency/ad9834.c
> @@ -29,8 +29,7 @@
>  /* Registers */
>  
>  #define AD9834_REG_CMD		0
> -#define AD9834_REG_FREQ0	BIT(14)
> -#define AD9834_REG_FREQ1	BIT(15)
> +#define AD9834_REG_FREQ(chann)	(BIT(14) << (chann))

That is rather confusing... 

Perhaps we can represent this as a variable that is 3 bits wide, with values that
correspond to the different settings.


So define
#define AD7834_REG_ADDR_MASK GENMASK(15,13)
#define AD7834_REG_FREQ0 2
#define AD7834_REG_FREQ1 4
#define AD7834_REG_PHASE0 6
#define AD7834_REG_PHASE0 7

And use FIELD_SET(reg, AD7834_REG_ADDR_MASK, AD7834_REG_FREQ0) etc.

or something along those lines. It's a bit nasty because in the FREQ
case the bottom bit is actually part of the value.
Hmm. May just need two definitions of the mask. how about.
#define AD7834_REG_FREQ_MASK GENMASK(15,14)
#define AD7834_REG_FREQ0 1
#define AD7934_REG_FREQ1 2
 
#define AD7834_REG_PHASE_MASK GENMASK(15,13)
#define AD7834_REG_PHASE0 6
#define AD7834_REG_PHASE1 7
?

>  #define AD9834_REG_PHASE0	(BIT(15) | BIT(14))
>  #define AD9834_REG_PHASE1	(BIT(15) | BIT(14) | BIT(13))
>  
> @@ -81,6 +80,9 @@ struct ad9834_state {
>  	struct spi_message		freq_msg;
>  	struct mutex                    lock;   /* protect sensor state */
>  
> +	unsigned long			frequency0;
> +	unsigned long			frequency1;
> +
>  	/*
>  	 * DMA (thus cache coherency maintenance) requires the
>  	 * transfer buffers to live in their own cache lines.
> @@ -100,6 +102,25 @@ enum ad9834_supported_device_ids {
>  	ID_AD9838,
>  };
>  
> +#define AD9833_CHANNEL(_chan) {						\
> +		.type = IIO_ALTVOLTAGE,					\
> +		.indexed = 1,						\
> +		.output = 1,						\
> +		.address = (_chan),					\

Not a lot of point in setting them both if they are always the same.

> +		.channel = (_chan),					\
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_FREQUENCY)	\
> +}
> +
> +static const struct iio_chan_spec ad9833_channels[] = {
> +	AD9833_CHANNEL(0),
> +	AD9833_CHANNEL(1),
> +};
> +
> +static const struct iio_chan_spec ad9834_channels[] = {
> +	AD9833_CHANNEL(0),
> +	AD9833_CHANNEL(1),
> +};

Umm. That needs some explaining.  Why have two identical arrays?
I'll guess that later patches will make them different?
That is fine, but you need a comment in the patch description to give
the reasoning.

> +
>  static unsigned int ad9834_calc_freqreg(unsigned long mclk, unsigned long fout)
>  {
>  	unsigned long long freqreg = (u64)fout * (u64)BIT(AD9834_FREQ_BITS);
> @@ -113,6 +134,7 @@ static int ad9834_write_frequency(struct ad9834_state *st,
>  {
>  	unsigned long clk_freq;
>  	unsigned long regval;
> +	int ret;
>  
>  	clk_freq = clk_get_rate(st->mclk);
>  
> @@ -121,13 +143,22 @@ static int ad9834_write_frequency(struct ad9834_state *st,
>  
>  	regval = ad9834_calc_freqreg(clk_freq, fout);
>  
> -	st->freq_data[0] = cpu_to_be16(addr | (regval &
> +	st->freq_data[0] = cpu_to_be16(AD9834_REG_FREQ(addr) | (regval &
>  				       RES_MASK(AD9834_FREQ_BITS / 2)));
> -	st->freq_data[1] = cpu_to_be16(addr | ((regval >>
> +	st->freq_data[1] = cpu_to_be16(AD9834_REG_FREQ(addr) | ((regval >>
>  				       (AD9834_FREQ_BITS / 2)) &
>  				       RES_MASK(AD9834_FREQ_BITS / 2)));
>  
> -	return spi_sync(st->spi, &st->freq_msg);
> +	ret = spi_sync(st->spi, &st->freq_msg);
> +	if (ret)
> +		return ret;
> +
> +	if (addr == 0)
> +		st->frequency0 = fout;

How about moving to an array you can just index with addr?
(or the enum I suggest below).

> +	else
> +		st->frequency1 = fout;
> +
> +	return 0;
>  }
>  
>  static int ad9834_write_phase(struct ad9834_state *st,
> @@ -140,6 +171,40 @@ static int ad9834_write_phase(struct ad9834_state *st,
>  	return spi_sync(st->spi, &st->msg);
>  }
>  
> +static int ad9834_read_raw(struct iio_dev *indio_dev,
> +			   struct iio_chan_spec const *chan,
> +			   int *val, int *val2, long mask)
> +{
> +	struct ad9834_state *st = iio_priv(indio_dev);
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_FREQUENCY:
> +		if (chan->address == 0)
> +			*val = st->frequency0;

As above, an array for frequency would tidy this up.

> +		else
> +			*val = st->frequency1;
> +		return IIO_VAL_INT;
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static int ad9834_write_raw(struct iio_dev *indio_dev,
> +			    struct iio_chan_spec const *chan,
> +			    int val, int val2, long mask)
> +{
> +	struct ad9834_state *st = iio_priv(indio_dev);
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_FREQUENCY:
> +		return ad9834_write_frequency(st, chan->address, val);
> +	default:
> +		return  -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +
>  static ssize_t ad9834_write(struct device *dev,
>  			    struct device_attribute *attr,
>  			    const char *buf,
> @@ -157,10 +222,6 @@ static ssize_t ad9834_write(struct device *dev,
>  
>  	mutex_lock(&st->lock);
>  	switch ((u32)this_attr->address) {
> -	case AD9834_REG_FREQ0:
> -	case AD9834_REG_FREQ1:
> -		ret = ad9834_write_frequency(st, this_attr->address, val);
> -		break;
>  	case AD9834_REG_PHASE0:
>  	case AD9834_REG_PHASE1:
>  		ret = ad9834_write_phase(st, this_attr->address, val);
> @@ -323,8 +384,6 @@ static IIO_DEVICE_ATTR(out_altvoltage0_out1_wavetype_available, 0444,
>   * see dds.h for further information
>   */
>  
> -static IIO_DEV_ATTR_FREQ(0, 0, 0200, NULL, ad9834_write, AD9834_REG_FREQ0);
> -static IIO_DEV_ATTR_FREQ(0, 1, 0200, NULL, ad9834_write, AD9834_REG_FREQ1);
>  static IIO_DEV_ATTR_FREQSYMBOL(0, 0200, NULL, ad9834_write, AD9834_FSEL);
>  static IIO_CONST_ATTR_FREQ_SCALE(0, "1"); /* 1Hz */
>  
> @@ -342,8 +401,6 @@ static IIO_DEV_ATTR_OUT_WAVETYPE(0, 0, ad9834_store_wavetype, 0);
>  static IIO_DEV_ATTR_OUT_WAVETYPE(0, 1, ad9834_store_wavetype, 1);
>  
>  static struct attribute *ad9834_attributes[] = {
> -	&iio_dev_attr_out_altvoltage0_frequency0.dev_attr.attr,
> -	&iio_dev_attr_out_altvoltage0_frequency1.dev_attr.attr,
>  	&iio_const_attr_out_altvoltage0_frequency_scale.dev_attr.attr,
>  	&iio_dev_attr_out_altvoltage0_phase0.dev_attr.attr,
>  	&iio_dev_attr_out_altvoltage0_phase1.dev_attr.attr,
> @@ -361,8 +418,6 @@ static struct attribute *ad9834_attributes[] = {
>  };
>  
>  static struct attribute *ad9833_attributes[] = {
> -	&iio_dev_attr_out_altvoltage0_frequency0.dev_attr.attr,
> -	&iio_dev_attr_out_altvoltage0_frequency1.dev_attr.attr,
>  	&iio_const_attr_out_altvoltage0_frequency_scale.dev_attr.attr,
>  	&iio_dev_attr_out_altvoltage0_phase0.dev_attr.attr,
>  	&iio_dev_attr_out_altvoltage0_phase1.dev_attr.attr,
> @@ -384,11 +439,15 @@ static const struct attribute_group ad9833_attribute_group = {
>  };
>  
>  static const struct iio_info ad9834_info = {
> +	.write_raw = &ad9834_write_raw,
> +	.read_raw = &ad9834_read_raw,
>  	.attrs = &ad9834_attribute_group,
>  	.driver_module = THIS_MODULE,
>  };
>  
>  static const struct iio_info ad9833_info = {
> +	.write_raw = &ad9834_write_raw,
> +	.read_raw = &ad9834_read_raw,
>  	.attrs = &ad9833_attribute_group,
>  	.driver_module = THIS_MODULE,
>  };
> @@ -435,9 +494,13 @@ static int ad9834_probe(struct spi_device *spi)
>  	switch (st->devid) {
>  	case ID_AD9833:
>  	case ID_AD9837:
> +		indio_dev->channels = ad9833_channels;
> +		indio_dev->num_channels = ARRAY_SIZE(ad9833_channels);
>  		indio_dev->info = &ad9833_info;
>  		break;
>  	default:
> +		indio_dev->channels = ad9834_channels;
> +		indio_dev->num_channels = ARRAY_SIZE(ad9834_channels);
>  		indio_dev->info = &ad9834_info;
>  		break;
>  	}
> @@ -474,11 +537,11 @@ static int ad9834_probe(struct spi_device *spi)
>  		goto error_clock_unprepare;
>  	}
>  
> -	ret = ad9834_write_frequency(st, AD9834_REG_FREQ0, 1000000);
> +	ret = ad9834_write_frequency(st, 0, 1000000);
Use an enum for that second variable, to make it clear that we are
picking which frequency value is being set and that there are only two
possible.

>  	if (ret)
>  		goto error_clock_unprepare;
>  
> -	ret = ad9834_write_frequency(st, AD9834_REG_FREQ1, 5000000);
> +	ret = ad9834_write_frequency(st, 1, 5000000);
>  	if (ret)
>  		goto error_clock_unprepare;
>