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[v2,0/4] iio: vcnl4000: Export near level property for proximity sensor

Message ID cover.1584380360.git.agx@sigxcpu.org
Headers show
Series iio: vcnl4000: Export near level property for proximity sensor | expand

Message

Guido Günther March 16, 2020, 5:46 p.m. UTC
If an object can be considered close to the device that has the proximity
sensor built in is hardware dependent. Allowing to configure the property via
device tree allows to export this device specific value to userspace via
ext_info. This is useful for e.g. iio-sensor-proxy.

This came up when adding proximity support to iio-sensor-proxy [1], [2], it is
not meant as a vcnl4000 thing but rather as something useful for other proximity
sensors too in the future.

Changes from v1:
- as per review comments by Jonathan Cameron
  https://lore.kernel.org/linux-iio/20200221120519.43b72007@archlinux/
  Document new sysfs file in Documentation/ABI/testing/sysfs-bus-iio-proximity
- convert bindings to yaml
- bindings: fix typo in near-level property

[1]: https://gitlab.freedesktop.org/hadess/iio-sensor-proxy/merge_requests/298
[2]: https://lore.kernel.org/linux-iio/20200210154153.GA26903@bogon.m.sigxcpu.org/

Guido Günther (4):
  dt-bindings: iio: vcnl4000: convert bindings to YAML format
  dt-bindings: iio: light: vcnl4000: Add near-level
  iio: vcnl4000: Export near level property for proximity sensor
  Documentation: ABI: document IIO in_proximity_near_level file

 .../ABI/testing/sysfs-bus-iio-proximity       | 10 ++++
 .../bindings/iio/light/vcnl4000.txt           | 24 ---------
 .../bindings/iio/light/vcnl4000.yaml          | 53 +++++++++++++++++++
 drivers/iio/light/vcnl4000.c                  | 26 +++++++++
 4 files changed, 89 insertions(+), 24 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-proximity
 delete mode 100644 Documentation/devicetree/bindings/iio/light/vcnl4000.txt
 create mode 100644 Documentation/devicetree/bindings/iio/light/vcnl4000.yaml

Comments

Lars-Peter Clausen March 16, 2020, 6:23 p.m. UTC | #1
On 3/16/20 6:46 PM, Guido Günther wrote:
> [...]
> +static ssize_t vcnl4000_read_near_level(struct iio_dev *indio_dev,
> +					uintptr_t priv,
> +					const struct iio_chan_spec *chan,
> +					char *buf)
> +{
> +	struct vcnl4000_data *data = iio_priv(indio_dev);
> +
> +	return sprintf(buf, "%u\n", data->near_level);
> +}
> +
> +static const struct iio_chan_spec_ext_info vcnl4000_ext_info[] = {
> +	{
> +		.name = "near_level",

Generally having properties with a underscore in them breaks generic 
parsing of the property name by userspace applications. This is because 
we use underscores to separate different components (type, modifier, 
etc.) of the attribute from each other.

Do you think calling this "nearlevel" would work?

I know there are existing bad examples of properties that use an 
underscore, but we should try to limit introducing new ones.

> +		.shared = IIO_SEPARATE,
> +		.read = vcnl4000_read_near_level,
> +	},
> +	{ /* sentinel */ }
> +};
> +
>   static const struct iio_chan_spec vcnl4000_channels[] = {
>   	{
>   		.type = IIO_LIGHT,
> @@ -350,6 +371,7 @@ static const struct iio_chan_spec vcnl4000_channels[] = {
>   	}, {
>   		.type = IIO_PROXIMITY,
>   		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
> +		.ext_info = vcnl4000_ext_info,
>   	}
>   };
>   
> @@ -439,6 +461,10 @@ static int vcnl4000_probe(struct i2c_client *client,
>   	dev_dbg(&client->dev, "%s Ambient light/proximity sensor, Rev: %02x\n",
>   		data->chip_spec->prod, data->rev);
>   
> +	if (device_property_read_u32(&client->dev, "near-level",
> +				     &data->near_level) < 0)
> +		data->near_level = 0;
> +
>   	indio_dev->dev.parent = &client->dev;
>   	indio_dev->info = &vcnl4000_info;
>   	indio_dev->channels = vcnl4000_channels;
Guido Günther March 17, 2020, 12:05 p.m. UTC | #2
Hi,
On Mon, Mar 16, 2020 at 07:23:01PM +0100, Lars-Peter Clausen wrote:
> On 3/16/20 6:46 PM, Guido Günther wrote:
> > [...]
> > +static ssize_t vcnl4000_read_near_level(struct iio_dev *indio_dev,
> > +					uintptr_t priv,
> > +					const struct iio_chan_spec *chan,
> > +					char *buf)
> > +{
> > +	struct vcnl4000_data *data = iio_priv(indio_dev);
> > +
> > +	return sprintf(buf, "%u\n", data->near_level);
> > +}
> > +
> > +static const struct iio_chan_spec_ext_info vcnl4000_ext_info[] = {
> > +	{
> > +		.name = "near_level",
> 
> Generally having properties with a underscore in them breaks generic parsing
> of the property name by userspace applications. This is because we use
> underscores to separate different components (type, modifier, etc.) of the
> attribute from each other.
> 
> Do you think calling this "nearlevel" would work?

That works as well. I'll change that for v3.

For my education: Is the type, modifier policy written down somewhere
(similar to
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/leds/leds-class.rst#n44
)?

Cheers,
 -- Guido

> 
> I know there are existing bad examples of properties that use an underscore,
> but we should try to limit introducing new ones.
> 
> > +		.shared = IIO_SEPARATE,
> > +		.read = vcnl4000_read_near_level,
> > +	},
> > +	{ /* sentinel */ }
> > +};
> > +
> >   static const struct iio_chan_spec vcnl4000_channels[] = {
> >   	{
> >   		.type = IIO_LIGHT,
> > @@ -350,6 +371,7 @@ static const struct iio_chan_spec vcnl4000_channels[] = {
> >   	}, {
> >   		.type = IIO_PROXIMITY,
> >   		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
> > +		.ext_info = vcnl4000_ext_info,
> >   	}
> >   };
> > @@ -439,6 +461,10 @@ static int vcnl4000_probe(struct i2c_client *client,
> >   	dev_dbg(&client->dev, "%s Ambient light/proximity sensor, Rev: %02x\n",
> >   		data->chip_spec->prod, data->rev);
> > +	if (device_property_read_u32(&client->dev, "near-level",
> > +				     &data->near_level) < 0)
> > +		data->near_level = 0;
> > +
> >   	indio_dev->dev.parent = &client->dev;
> >   	indio_dev->info = &vcnl4000_info;
> >   	indio_dev->channels = vcnl4000_channels;
> 
>
Lars-Peter Clausen March 17, 2020, 1:11 p.m. UTC | #3
On 3/17/20 1:05 PM, Guido Günther wrote:
> Hi,
> On Mon, Mar 16, 2020 at 07:23:01PM +0100, Lars-Peter Clausen wrote:
>> On 3/16/20 6:46 PM, Guido Günther wrote:
>>> [...]
>>> +static ssize_t vcnl4000_read_near_level(struct iio_dev *indio_dev,
>>> +					uintptr_t priv,
>>> +					const struct iio_chan_spec *chan,
>>> +					char *buf)
>>> +{
>>> +	struct vcnl4000_data *data = iio_priv(indio_dev);
>>> +
>>> +	return sprintf(buf, "%u\n", data->near_level);
>>> +}
>>> +
>>> +static const struct iio_chan_spec_ext_info vcnl4000_ext_info[] = {
>>> +	{
>>> +		.name = "near_level",
>> Generally having properties with a underscore in them breaks generic parsing
>> of the property name by userspace applications. This is because we use
>> underscores to separate different components (type, modifier, etc.) of the
>> attribute from each other.
>>
>> Do you think calling this "nearlevel" would work?
> That works as well. I'll change that for v3.
>
> For my education: Is the type, modifier policy written down somewhere
> (similar to
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/leds/leds-class.rst#n44
> )?

Good point, this is quite badly documented at the moment.

The only thing I could find is this presentation by Daniel 
https://events.static.linuxfound.org/sites/events/files/slides/lceu15_baluta.pdf#page=9

- Lars
Andy Shevchenko March 22, 2020, 12:21 a.m. UTC | #4
On Mon, Mar 16, 2020 at 7:47 PM Guido Günther <agx@sigxcpu.org> wrote:
>
> When an object can be considered close to the sensor is hardware
> dependent. Allowing to configure the property via device tree
> allows to configure this device specific value.
>
> This is useful for e.g. iio-sensor-proxy to indicate to userspace
> if an object is close to the sensor.

...

> @@ -342,6 +343,26 @@ static const struct vcnl4000_chip_spec vcnl4000_chip_spec_cfg[] = {
>         },
>  };
>

> +

No need for this blank line.

> +static ssize_t vcnl4000_read_near_level(struct iio_dev *indio_dev,
> +                                       uintptr_t priv,
> +                                       const struct iio_chan_spec *chan,
> +                                       char *buf)

...

> +       if (device_property_read_u32(&client->dev, "near-level",
> +                                    &data->near_level) < 0)

It doesn't return > 0. So, you may drop that and put everything to one
line I think.

> +               data->near_level = 0;