Re: [PATCH v2] staging: iio: ad7192: implement IIO_CHAN_INFO_SAMP_FREQ

[Jonathan Cameron <jic23@kernel.org>]

On 03/10/16 05:00, Eva Rachel Retuya wrote:
> On Sat, Oct 01, 2016 at 12:35:26PM +0100, Jonathan Cameron wrote:
>> On 01/10/16 08:49, Eva Rachel Retuya wrote:
>>> This driver predates the availability of IIO_CHAN_INFO_SAMP_FREQ attribute
>>> wherein usage has some advantages like it can be accessed by in-kernel
>>> consumers as well as reduces the code size.
>>>
>>> Therefore, use IIO_CHAN_INFO_SAMP_FREQ to implement the sampling_frequency
>>> attribute instead of using IIO_DEV_ATTR_SAMP_FREQ() macro.
>>>
>>> Move code from the functions associated with IIO_DEV_ATTR_SAMP_FREQ() into
>>> respective read and write hooks with the mask set to IIO_CHAN_INFO_SAMP_FREQ.
>>>
>>> Signed-off-by: Eva Rachel Retuya <eraretuya@gmail.com>
>> Given this is heading away from the generic staging fixes and into the
>> list of specific IIO tasks, please do make sure to cc the linux-iio
>> list.
>>
>> (I'd prefer that for all IIO touching patches - but give that's somewhat
>> of an oddity for staging I don't really mind that much)
>>
> 
> My apologies for that. I will include the linux-iio list in the future
> revisions and patch submissions. (cc'ing the list now..)
> 
>> Otherwise, almost perfect, but there is a weird corner in this driver.
>>
>> Take a look at what write_raw_get_fmt is set to...
>> For this write it should return be IIO_VAL_INT;
>>
> 
> I had set the return to IIO_VAL_INT already. Can you please point out where
> else I had missed?
You return that for the read which is quite correct, the interesting one
is the write_raw callback change.  Have a bit of a dig into how that knows
what it is getting (in val and val2).

> 
>> Lars / Michael, this driver is only a very small distance from being
>> fine to move out of staging.  I'm basically seeing two bits of
>> custom ABI that need documenting and review, but otherwise post
>> this cleanup looks in pretty good state to me.
>>
> 
> By any chance, are you referring to these:
> static IIO_DEVICE_ATTR_NAMED(in_v_m_v_scale_available,
> 			     in_voltage-voltage_scale_available,
> 			     S_IRUGO, ad7192_show_scale_available, NULL, 0);
> 
> static IIO_DEVICE_ATTR(in_voltage_scale_available, S_IRUGO,
> 		       ad7192_show_scale_available, NULL, 0);
Those two are actually standard ABI (though there is a long term plan to handle
the available attributes in a nicer fashion)

The custom pair are bridge_switch_en and ac_excitation_en,
> 
> Can you please guide me as to what to do next on the "documenting" part,
> and should I send a patchset instead with this and the documentation bit
> put together?
This one definitely wants input from Lars-Peter.  I don't know the hardware
at all.  It might be possible to work out what these are well enough to
figure out if the ABI is 'right' (by which I mean well defined within the
full set of IIO ABIs) and to work out some documentation.

However such docs would still want a review from Lars or one of his colleagues.
> 
> Thanks for the feedback,
You are welcome.

Jonathan
> Eva
> 
>> Thanks,
>>
>> Jonathan
>>> ---
>>> Changes in v2:
>>> * Make commit message more detailed
>>> * Fix tiny bug about bypassing iio_device_release_direct_mode()
>>> * Remove unneeded goto and use break instead
>>>
>>>  drivers/staging/iio/adc/ad7192.c       | 75 ++++++++++------------------------
>>>  include/linux/iio/adc/ad_sigma_delta.h |  1 +
>>>  2 files changed, 22 insertions(+), 54 deletions(-)
>>>
>>> diff --git a/drivers/staging/iio/adc/ad7192.c b/drivers/staging/iio/adc/ad7192.c
>>> index 1cf6b79..e6e4505 100644
>>> --- a/drivers/staging/iio/adc/ad7192.c
>>> +++ b/drivers/staging/iio/adc/ad7192.c
>>> @@ -322,57 +322,6 @@ out:
>>>  	return ret;
>>>  }
>>>  
>>> -static ssize_t ad7192_read_frequency(struct device *dev,
>>> -				     struct device_attribute *attr,
>>> -				     char *buf)
>>> -{
>>> -	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>>> -	struct ad7192_state *st = iio_priv(indio_dev);
>>> -
>>> -	return sprintf(buf, "%d\n", st->mclk /
>>> -			(st->f_order * 1024 * AD7192_MODE_RATE(st->mode)));
>>> -}
>>> -
>>> -static ssize_t ad7192_write_frequency(struct device *dev,
>>> -				      struct device_attribute *attr,
>>> -				      const char *buf,
>>> -				      size_t len)
>>> -{
>>> -	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>>> -	struct ad7192_state *st = iio_priv(indio_dev);
>>> -	unsigned long lval;
>>> -	int div, ret;
>>> -
>>> -	ret = kstrtoul(buf, 10, &lval);
>>> -	if (ret)
>>> -		return ret;
>>> -	if (lval == 0)
>>> -		return -EINVAL;
>>> -
>>> -	ret = iio_device_claim_direct_mode(indio_dev);
>>> -	if (ret)
>>> -		return ret;
>>> -
>>> -	div = st->mclk / (lval * st->f_order * 1024);
>>> -	if (div < 1 || div > 1023) {
>>> -		ret = -EINVAL;
>>> -		goto out;
>>> -	}
>>> -
>>> -	st->mode &= ~AD7192_MODE_RATE(-1);
>>> -	st->mode |= AD7192_MODE_RATE(div);
>>> -	ad_sd_write_reg(&st->sd, AD7192_REG_MODE, 3, st->mode);
>>> -
>>> -out:
>>> -	iio_device_release_direct_mode(indio_dev);
>>> -
>>> -	return ret ? ret : len;
>>> -}
>>> -
>>> -static IIO_DEV_ATTR_SAMP_FREQ(S_IWUSR | S_IRUGO,
>>> -		ad7192_read_frequency,
>>> -		ad7192_write_frequency);
>>> -
>>>  static ssize_t
>>>  ad7192_show_scale_available(struct device *dev,
>>>  			    struct device_attribute *attr, char *buf)
>>> @@ -471,7 +420,6 @@ static IIO_DEVICE_ATTR(ac_excitation_en, S_IRUGO | S_IWUSR,
>>>  		       AD7192_REG_MODE);
>>>  
>>>  static struct attribute *ad7192_attributes[] = {
>>> -	&iio_dev_attr_sampling_frequency.dev_attr.attr,
>>>  	&iio_dev_attr_in_v_m_v_scale_available.dev_attr.attr,
>>>  	&iio_dev_attr_in_voltage_scale_available.dev_attr.attr,
>>>  	&iio_dev_attr_bridge_switch_en.dev_attr.attr,
>>> @@ -484,7 +432,6 @@ static const struct attribute_group ad7192_attribute_group = {
>>>  };
>>>  
>>>  static struct attribute *ad7195_attributes[] = {
>>> -	&iio_dev_attr_sampling_frequency.dev_attr.attr,
>>>  	&iio_dev_attr_in_v_m_v_scale_available.dev_attr.attr,
>>>  	&iio_dev_attr_in_voltage_scale_available.dev_attr.attr,
>>>  	&iio_dev_attr_bridge_switch_en.dev_attr.attr,
>>> @@ -536,6 +483,10 @@ static int ad7192_read_raw(struct iio_dev *indio_dev,
>>>  		if (chan->type == IIO_TEMP)
>>>  			*val -= 273 * ad7192_get_temp_scale(unipolar);
>>>  		return IIO_VAL_INT;
>>> +	case IIO_CHAN_INFO_SAMP_FREQ:
>>> +		*val = st->mclk /
>>> +			(st->f_order * 1024 * AD7192_MODE_RATE(st->mode));
>>> +		return IIO_VAL_INT;
>>>  	}
>>>  
>>>  	return -EINVAL;
>>> @@ -548,7 +499,7 @@ static int ad7192_write_raw(struct iio_dev *indio_dev,
>>>  			    long mask)
>>>  {
>>>  	struct ad7192_state *st = iio_priv(indio_dev);
>>> -	int ret, i;
>>> +	int ret, i, div;
>>>  	unsigned int tmp;
>>>  
>>>  	ret = iio_device_claim_direct_mode(indio_dev);
>>> @@ -572,6 +523,22 @@ static int ad7192_write_raw(struct iio_dev *indio_dev,
>>>  				break;
>>>  			}
>>>  		break;
>>> +	case IIO_CHAN_INFO_SAMP_FREQ:
>>> +		if (!val) {
>>> +			ret = -EINVAL;
>>> +			break;
>>> +		}
>>> +
>>> +		div = st->mclk / (val * st->f_order * 1024);
>>> +		if (div < 1 || div > 1023) {
>>> +			ret = -EINVAL;
>>> +			break;
>>> +		}
>>> +
>>> +		st->mode &= ~AD7192_MODE_RATE(-1);
>>> +		st->mode |= AD7192_MODE_RATE(div);
>>> +		ad_sd_write_reg(&st->sd, AD7192_REG_MODE, 3, st->mode);
>>> +		break;
>>>  	default:
>>>  		ret = -EINVAL;
>>>  	}
>>> diff --git a/include/linux/iio/adc/ad_sigma_delta.h b/include/linux/iio/adc/ad_sigma_delta.h
>>> index e7fdec4..5ba430c 100644
>>> --- a/include/linux/iio/adc/ad_sigma_delta.h
>>> +++ b/include/linux/iio/adc/ad_sigma_delta.h
>>> @@ -136,6 +136,7 @@ int ad_sd_validate_trigger(struct iio_dev *indio_dev, struct iio_trigger *trig);
>>>  		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
>>>  			BIT(IIO_CHAN_INFO_OFFSET), \
>>>  		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
>>> +		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ), \
>>>  		.scan_index = (_si), \
>>>  		.scan_type = { \
>>>  			.sign = 'u', \
>>>
>>
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