[PATCH 1/2] devicetree: xilinx-xadc: Add optional xlnx,extend-name property

[PATCH 1/2] devicetree: xilinx-xadc: Add optional xlnx,extend-name property

[Xander Huff]

To better facilitate user-mode access to optional aux channels, allow
device trees to specify a custom extended name for defined channels.

Signed-off-by: Xander Huff <xander.huff-acOepvfBmUk@public.gmane.org>
Reviewed-by: Joe Hershberger <joe.hershberger-acOepvfBmUk@public.gmane.org>
Reviewed-by: Josh Cartwright <joshc-acOepvfBmUk@public.gmane.org>
--
Natinst-ReviewBoard-ID: 97119
---
 Documentation/devicetree/bindings/iio/adc/xilinx-xadc.txt | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Documentation/devicetree/bindings/iio/adc/xilinx-xadc.txt b/Documentation/devicetree/bindings/iio/adc/xilinx-xadc.txt
index d71258e..4c5a60b 100644
--- a/Documentation/devicetree/bindings/iio/adc/xilinx-xadc.txt
+++ b/Documentation/devicetree/bindings/iio/adc/xilinx-xadc.txt
@@ -68,6 +68,8 @@ Optional properties:
 			  Note each channel number should only be used at most
 			  once.
 		Optional properties:
+			* xlnx,extend-name: Custom extended name for the
+			  channel.
 			* xlnx,bipolar: If set the channel is used in bipolar
 			  mode.
 
@@ -107,6 +109,7 @@ Examples:
 			#size-cells = <0>;
 			channel@0 {
 				reg = <0>;
+				xlnx,extend-name = "vin_v";
 				xlnx,bipolar;
 			};
 		};
-- 
1.9.1

[PATCH 2/2] iio: adc: xilinx-xadc: Add xlnx,extend-name as an optional argument for aux channels

[Xander Huff]

To better facilitate user-mode access to optional aux channels, allow
device trees to specify a custom extended name for defined channels.

Signed-off-by: Xander Huff <xander.huff-acOepvfBmUk@public.gmane.org>
Reviewed-by: Joe Hershberger <joe.hershberger-acOepvfBmUk@public.gmane.org>
Reviewed-by: Josh Cartwright <joshc-acOepvfBmUk@public.gmane.org>
--
Natinst-ReviewBoard-ID: 97119
---
 drivers/iio/adc/xilinx-xadc-core.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/iio/adc/xilinx-xadc-core.c b/drivers/iio/adc/xilinx-xadc-core.c
index a221f73..cf1d2f9 100644
--- a/drivers/iio/adc/xilinx-xadc-core.c
+++ b/drivers/iio/adc/xilinx-xadc-core.c
@@ -1118,6 +1118,9 @@ static int xadc_parse_dt(struct iio_dev *indio_dev, struct device_node *np,
 			if (ret || reg > 16)
 				continue;
 
+			of_property_read_string(child, "xlnx,extend-name",
+						&chan->extend_name);
+
 			if (of_property_read_bool(child, "xlnx,bipolar"))
 				chan->scan_type.sign = 's';
 
-- 
1.9.1

Re: [PATCH 2/2] iio: adc: xilinx-xadc: Add xlnx,extend-name as an optional argument for aux channels

[Lars-Peter Clausen]

On 05/08/2015 12:44 AM, Xander Huff wrote:
> To better facilitate user-mode access to optional aux channels, allow
> device trees to specify a custom extended name for defined channels.

Hi,

'extend-name' is kind of a IIO specific term. I think a better name in the 
devicetree context would be 'label'. That's used everywhere else when giving 
a short description string to a node.

- Lars

[PATCH v2 1/2] devicetree: xilinx-xadc: Add optional label property

[Xander Huff]

To better facilitate user-mode access to optional aux channels, allow
device trees to specify a custom label for defined channels.

Signed-off-by: Xander Huff <xander.huff-acOepvfBmUk@public.gmane.org>
Reviewed-by: Joe Hershberger <joe.hershberger-acOepvfBmUk@public.gmane.org>
Reviewed-by: Josh Cartwright <joshc-acOepvfBmUk@public.gmane.org>
---
 Documentation/devicetree/bindings/iio/adc/xilinx-xadc.txt | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/devicetree/bindings/iio/adc/xilinx-xadc.txt b/Documentation/devicetree/bindings/iio/adc/xilinx-xadc.txt
index d71258e..19dcd96 100644
--- a/Documentation/devicetree/bindings/iio/adc/xilinx-xadc.txt
+++ b/Documentation/devicetree/bindings/iio/adc/xilinx-xadc.txt
@@ -68,6 +68,7 @@ Optional properties:
 			  Note each channel number should only be used at most
 			  once.
 		Optional properties:
+			* label: Custom label for the channel.
 			* xlnx,bipolar: If set the channel is used in bipolar
 			  mode.
 
@@ -107,6 +108,7 @@ Examples:
 			#size-cells = <0>;
 			channel@0 {
 				reg = <0>;
+				label = "vin_v";
 				xlnx,bipolar;
 			};
 		};
-- 
1.9.1

[PATCH v2 2/2] iio: adc: xilinx-xadc: Add label as an optional argument for aux channels

[Xander Huff]

To better facilitate user-mode access to optional aux channels, allow
device trees to specify a custom label for defined channels.

Signed-off-by: Xander Huff <xander.huff-acOepvfBmUk@public.gmane.org>
Reviewed-by: Joe Hershberger <joe.hershberger-acOepvfBmUk@public.gmane.org>
Reviewed-by: Josh Cartwright <joshc-acOepvfBmUk@public.gmane.org>
---
 drivers/iio/adc/xilinx-xadc-core.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/iio/adc/xilinx-xadc-core.c b/drivers/iio/adc/xilinx-xadc-core.c
index ce93bd8..bda4241 100644
--- a/drivers/iio/adc/xilinx-xadc-core.c
+++ b/drivers/iio/adc/xilinx-xadc-core.c
@@ -1119,6 +1119,9 @@ static int xadc_parse_dt(struct iio_dev *indio_dev, struct device_node *np,
 			if (ret || reg > 16)
 				continue;
 
+			of_property_read_string(child, "label",
+						&chan->extend_name);
+
 			if (of_property_read_bool(child, "xlnx,bipolar"))
 				chan->scan_type.sign = 's';
 
-- 
1.9.1

Re: [PATCH v2 2/2] iio: adc: xilinx-xadc: Add label as an optional argument for aux channels

[Jonathan Cameron]

On 20/05/15 16:22, Xander Huff wrote:
> To better facilitate user-mode access to optional aux channels, allow
> device trees to specify a custom label for defined channels.
> 
> Signed-off-by: Xander Huff <xander.huff-acOepvfBmUk@public.gmane.org>
> Reviewed-by: Joe Hershberger <joe.hershberger-acOepvfBmUk@public.gmane.org>
> Reviewed-by: Josh Cartwright <joshc-acOepvfBmUk@public.gmane.org>
> ---
>  drivers/iio/adc/xilinx-xadc-core.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/iio/adc/xilinx-xadc-core.c b/drivers/iio/adc/xilinx-xadc-core.c
> index ce93bd8..bda4241 100644
> --- a/drivers/iio/adc/xilinx-xadc-core.c
> +++ b/drivers/iio/adc/xilinx-xadc-core.c
> @@ -1119,6 +1119,9 @@ static int xadc_parse_dt(struct iio_dev *indio_dev, struct device_node *np,
>  			if (ret || reg > 16)
>  				continue;
>  
> +			of_property_read_string(child, "label",
> +						&chan->extend_name);
> +
>  			if (of_property_read_bool(child, "xlnx,bipolar"))
>  				chan->scan_type.sign = 's';
>  
> 
I think what Lars was suggesting was a change to the IIO side of this rather than
just changing the device tree binding.  Perhaps an additional per channel attribute
called _label which would allow for board specific labelling?

Re: [PATCH v2 2/2] iio: adc: xilinx-xadc: Add label as an optional argument for aux channels

[Josh Cartwright]

[-- Attachment #1: Type: text/plain, Size: 2063 bytes --]

On Sun, Jun 07, 2015 at 05:49:26PM +0100, Jonathan Cameron wrote:
> On 20/05/15 16:22, Xander Huff wrote:
> > To better facilitate user-mode access to optional aux channels, allow
> > device trees to specify a custom label for defined channels.
> > 
> > Signed-off-by: Xander Huff <xander.huff-acOepvfBmUk@public.gmane.org>
> > Reviewed-by: Joe Hershberger <joe.hershberger-acOepvfBmUk@public.gmane.org>
> > Reviewed-by: Josh Cartwright <joshc-acOepvfBmUk@public.gmane.org>
> > ---
> >  drivers/iio/adc/xilinx-xadc-core.c | 3 +++
> >  1 file changed, 3 insertions(+)
> > 
> > diff --git a/drivers/iio/adc/xilinx-xadc-core.c b/drivers/iio/adc/xilinx-xadc-core.c
> > index ce93bd8..bda4241 100644
> > --- a/drivers/iio/adc/xilinx-xadc-core.c
> > +++ b/drivers/iio/adc/xilinx-xadc-core.c
> > @@ -1119,6 +1119,9 @@ static int xadc_parse_dt(struct iio_dev *indio_dev, struct device_node *np,
> >  			if (ret || reg > 16)
> >  				continue;
> >  
> > +			of_property_read_string(child, "label",
> > +						&chan->extend_name);
> > +
> >  			if (of_property_read_bool(child, "xlnx,bipolar"))
> >  				chan->scan_type.sign = 's';
> >  
> > 
> I think what Lars was suggesting was a change to the IIO side of this rather than
> just changing the device tree binding.

I'm not so sure.  His observation was just that the typical name of
these properties is 'label', which I think makes sense and is commonly
used.

Naming things is hard.

Perhaps, though, an improvement may be made if we lifted this out of the
xadc driver and moved it into the IIO core (I can't imagine that this
driver is the only one representing each channel with a separate node in
DT).

> Perhaps an additional per channel attribute called _label which would
> allow for board specific labelling?

This would seem a bit odd in DT-land; if a user wanted a different label
name for their board, they would just rename it in their device tree for
that board.  Fortunately, with the structured dtsi include files, this
is pretty painless to do.

  Josh

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Re: [PATCH v2 2/2] iio: adc: xilinx-xadc: Add label as an optional argument for aux channels

[Jonathan Cameron]

On 08/06/15 14:49, Josh Cartwright wrote:
> On Sun, Jun 07, 2015 at 05:49:26PM +0100, Jonathan Cameron wrote:
>> On 20/05/15 16:22, Xander Huff wrote:
>>> To better facilitate user-mode access to optional aux channels, allow
>>> device trees to specify a custom label for defined channels.
>>>
>>> Signed-off-by: Xander Huff <xander.huff-acOepvfBmUk@public.gmane.org>
>>> Reviewed-by: Joe Hershberger <joe.hershberger-acOepvfBmUk@public.gmane.org>
>>> Reviewed-by: Josh Cartwright <joshc-acOepvfBmUk@public.gmane.org>
>>> ---
>>>  drivers/iio/adc/xilinx-xadc-core.c | 3 +++
>>>  1 file changed, 3 insertions(+)
>>>
>>> diff --git a/drivers/iio/adc/xilinx-xadc-core.c b/drivers/iio/adc/xilinx-xadc-core.c
>>> index ce93bd8..bda4241 100644
>>> --- a/drivers/iio/adc/xilinx-xadc-core.c
>>> +++ b/drivers/iio/adc/xilinx-xadc-core.c
>>> @@ -1119,6 +1119,9 @@ static int xadc_parse_dt(struct iio_dev *indio_dev, struct device_node *np,
>>>  			if (ret || reg > 16)
>>>  				continue;
>>>  
>>> +			of_property_read_string(child, "label",
>>> +						&chan->extend_name);
>>> +
>>>  			if (of_property_read_bool(child, "xlnx,bipolar"))
>>>  				chan->scan_type.sign = 's';
>>>  
>>>
>> I think what Lars was suggesting was a change to the IIO side of this rather than
>> just changing the device tree binding.
> 
> I'm not so sure.  His observation was just that the typical name of
> these properties is 'label', which I think makes sense and is commonly
> used.
> 
> Naming things is hard.
> 
> Perhaps, though, an improvement may be made if we lifted this out of the
> xadc driver and moved it into the IIO core (I can't imagine that this
> driver is the only one representing each channel with a separate node in
> DT).
> 
>> Perhaps an additional per channel attribute called _label which would
>> allow for board specific labelling?
> 
> This would seem a bit odd in DT-land; if a user wanted a different label
> name for their board, they would just rename it in their device tree for
> that board.  Fortunately, with the structured dtsi include files, this
> is pretty painless to do.
I don't really mind how it is done.  From a userspace point of view in IIO
though I think these belong in their own attribute rather than in the naming
of the attributes. The extended name stuff just makes for really hideous
userspace code!

Hence you could use the device tree node naming to provide it, or some other
means, but I'd like to have it provided to userspace as say

in_voltage0_label which when read provides the name as a straightforward string.

This would obviously want to be provided by the IIO core.

As for moving the per channel DT node stuff into the IIO core, at this point
there are a few drivers doing it, but far from all, so the best bet would be
a utility function to help the drivers handle the manipulation rather than
direct support in the core.

Jonathan
> 
>   Josh
> 

Re: [PATCH 2/2] iio: adc: xilinx-xadc: Add xlnx,extend-name as an optional argument for aux channels

[Jonathan Cameron]

On 19/05/15 18:53, Lars-Peter Clausen wrote:
> On 05/08/2015 12:44 AM, Xander Huff wrote:
>> To better facilitate user-mode access to optional aux channels, allow
>> device trees to specify a custom extended name for defined channels.
> 
> Hi,
> 
> 'extend-name' is kind of a IIO specific term. I think a better name in the devicetree context would be 'label'. That's used everywhere else when giving a short description string to a node.
> 
Hi Lars,

What do you think of the general idea?  I'm unconvinced we want to do this in channel naming.
Perhaps we want an additional attribute giving access to this sort of 'semantic' information?

Re: [PATCH 2/2] iio: adc: xilinx-xadc: Add xlnx,extend-name as an optional argument for aux channels

[Lars-Peter Clausen]

On 05/23/2015 01:23 PM, Jonathan Cameron wrote:
> On 19/05/15 18:53, Lars-Peter Clausen wrote:
>> On 05/08/2015 12:44 AM, Xander Huff wrote:
>>> To better facilitate user-mode access to optional aux channels, allow
>>> device trees to specify a custom extended name for defined channels.
>>
>> Hi,
>>
>> 'extend-name' is kind of a IIO specific term. I think a better name in the devicetree context would be 'label'. That's used everywhere else when giving a short description string to a node.
>>
> Hi Lars,
>
> What do you think of the general idea?  I'm unconvinced we want to do this in channel naming.
> Perhaps we want an additional attribute giving access to this sort of 'semantic' information?

I'm not convinced about it either. My gut feeling is that this is not the 
right approach, but I don't really have any better ideas at the moment.

Xander can you give a short description of how this information will be used 
by an application? Would having a label property for the channel also work 
for you (e.g. in_voltage0_label)?

- Lars

Re: [PATCH 2/2] iio: adc: xilinx-xadc: Add xlnx,extend-name as an optional argument for aux channels

[Xander Huff]

On 5/26/2015 4:38 AM, Lars-Peter Clausen wrote:
> On 05/23/2015 01:23 PM, Jonathan Cameron wrote:
>> On 19/05/15 18:53, Lars-Peter Clausen wrote:
>>> On 05/08/2015 12:44 AM, Xander Huff wrote:
>>>> To better facilitate user-mode access to optional aux channels, allow
>>>> device trees to specify a custom extended name for defined channels.
>>>
>>> Hi,
>>>
>>> 'extend-name' is kind of a IIO specific term. I think a better name in the
>>> devicetree context would be 'label'. That's used everywhere else when giving
>>> a short description string to a node.
>>>
>> Hi Lars,
>>
>> What do you think of the general idea?  I'm unconvinced we want to do this in
>> channel naming.
>> Perhaps we want an additional attribute giving access to this sort of
>> 'semantic' information?
>
> I'm not convinced about it either. My gut feeling is that this is not the right
> approach, but I don't really have any better ideas at the moment.
>
> Xander can you give a short description of how this information will be used by
> an application? Would having a label property for the channel also work for you
> (e.g. in_voltage0_label)?
>
> - Lars
>
We use 10 of the optional aux channels available in the XADC and have them wired 
up to specific power supplies. For example, channel 9 is connected to the 
current of a 6V power supply and channel 12 is connected to the voltage of that 
same supply, channel 4 is connected to the current of a 3.3V power supply and 
channel 5 is connected to its voltage.

Without adding extended names to distinguish these aux channels, the handles 
available inside /sys/bus/iio/devices/[device] are generic: in_voltage10_raw, 
in_voltage10_scale, for example. If I added the label 'user5v_v', then these 
handles would be in_voltage10_user5v_v_raw and in_voltage10_user5v_v_scale. This 
makes it a lot easier to get started and let the handles describe themselves, 
rather than having to look up which channels are connected to which things.

As far as using 'label' instead of 'extend-name', that's fine with me. I've 
already sent out a v2 using 'label' instead.

-- 
Xander Huff
Staff Software Engineer
National Instruments

Re: [PATCH 1/2] devicetree: xilinx-xadc: Add optional xlnx,extend-name property

[Jonathan Cameron]

On 07/05/15 18:44, Xander Huff wrote:
> To better facilitate user-mode access to optional aux channels, allow
> device trees to specify a custom extended name for defined channels.
> 
> Signed-off-by: Xander Huff <xander.huff-acOepvfBmUk@public.gmane.org>
> Reviewed-by: Joe Hershberger <joe.hershberger-acOepvfBmUk@public.gmane.org>
> Reviewed-by: Josh Cartwright <joshc-acOepvfBmUk@public.gmane.org>
> --
> Natinst-ReviewBoard-ID: 97119
Interesting idea. I'd like to let this sit for a fair while to see what
comments it gets.  If it makes sense for this driver, it probably makes
sense for a lot of others.  As such we may well want to have a general
binding for this, rather than one for just this part.

Thanks,

Jonathan
> ---
>  Documentation/devicetree/bindings/iio/adc/xilinx-xadc.txt | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/xilinx-xadc.txt b/Documentation/devicetree/bindings/iio/adc/xilinx-xadc.txt
> index d71258e..4c5a60b 100644
> --- a/Documentation/devicetree/bindings/iio/adc/xilinx-xadc.txt
> +++ b/Documentation/devicetree/bindings/iio/adc/xilinx-xadc.txt
> @@ -68,6 +68,8 @@ Optional properties:
>  			  Note each channel number should only be used at most
>  			  once.
>  		Optional properties:
> +			* xlnx,extend-name: Custom extended name for the
> +			  channel.
>  			* xlnx,bipolar: If set the channel is used in bipolar
>  			  mode.
>  
> @@ -107,6 +109,7 @@ Examples:
>  			#size-cells = <0>;
>  			channel@0 {
>  				reg = <0>;
> +				xlnx,extend-name = "vin_v";
>  				xlnx,bipolar;
>  			};
>  		};
>