linux-kernel - Re: [RFC 3/3] Documentation ABI: add PPS generators documentaion

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Message-ID: <fcb70129-f6f0-459f-b099-a2ca3a569095@enneenne.com>
Date: Wed, 9 Oct 2024 10:48:23 +0200
From: Rodolfo Giometti <giometti@...eenne.com>
To: Greg KH <greg@...ah.com>
Cc: linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
 Andrew Morton <akpm@...ux-foundation.org>, corbet@....net,
 Hall Christopher S <christopher.s.hall@...el.com>,
 Mohan Subramanian <subramanian.mohan@...el.com>, tglx@...utronix.de,
 andriy.shevchenko@...ux.intel.com, Dong Eddie <eddie.dong@...el.com>,
 N Pandith <pandith.n@...el.com>,
 T R Thejesh Reddy <thejesh.reddy.t.r@...el.com>,
 Zage David <david.zage@...el.com>,
 Chinnadurai Srinivasan <srinivasan.chinnadurai@...el.com>
Subject: Re: [RFC 3/3] Documentation ABI: add PPS generators documentaion

On 08/10/24 17:43, Greg KH wrote:
> On Tue, Oct 08, 2024 at 03:50:33PM +0200, Rodolfo Giometti wrote:
>> This patch adds the documentation for the ABI between the Linux kernel
>> and userspace regarding the PPS generators.
>>
>> Signed-off-by: Rodolfo Giometti <giometti@...eenne.com>
>> ---
>>   Documentation/ABI/testing/sysfs-pps-gen | 44 +++++++++++++++++++++++++
>>   1 file changed, 44 insertions(+)
>>   create mode 100644 Documentation/ABI/testing/sysfs-pps-gen
>>
>> diff --git a/Documentation/ABI/testing/sysfs-pps-gen b/Documentation/ABI/testing/sysfs-pps-gen
>> new file mode 100644
>> index 000000000000..9ad066cb3ce5
>> --- /dev/null
>> +++ b/Documentation/ABI/testing/sysfs-pps-gen
>> @@ -0,0 +1,44 @@
>> +What:		/sys/class/pps-gen/
>> +Date:		October 2024
>> +Contact:	Rodolfo Giometti <giometti@...eenne.com>
>> +Description:
>> +		The /sys/class/pps-gen/ directory will contain files and
>> +		directories that will provide a unified interface to
>> +		the PPS generators.
>> +
>> +What:		/sys/class/pps-gen/pps-genX/
>> +Date:		October 2024
>> +Contact:	Rodolfo Giometti <giometti@...eenne.com>
>> +Description:
>> +		The /sys/class/pps-gen/pps-genX/ directory is related to X-th
>> +		PPS generator into the system. Each directory will
>> +		contain files to manage and control its PPS generator.
>> +
>> +What:		/sys/class/pps-gen/pps-genX/enable
>> +Date:		October 2024
>> +Contact:	Rodolfo Giometti <giometti@...eenne.com>
>> +Description:
>> +		This write-only file enables or disables generation of the
>> +		PPS signal.
>> +
>> +What:		/sys/class/pps-gen/pps-genX/name
>> +Date:		October 2024
>> +Contact:	Rodolfo Giometti <giometti@...eenne.com>
>> +Description:
>> +		This read-only file reports the name of the X-th generator.
> 
> Again, why a name?  What is that for?

This can be useful in order to distinguish between different PPS generators in 
the system.

For example, the PARPORT generator is not very precise, and userspace 
applications should be able to know which generator corresponds to the device 
/dev/pps-gen0 or /dev/pps-gen1, etc.

> 
>> +
>> +What:		/sys/class/pps-gen/pps-genX/system
>> +Date:		October 2024
>> +Contact:	Rodolfo Giometti <giometti@...eenne.com>
>> +Description:
>> +		This read-only file returns "1" if the generator takes the
>> +		timing from the system clock, while it returns "0" if not
>> +		(i.e. from a peripheral device clock).
>> +
>> +What:		/sys/class/pps-gen/pps-genX/time
>> +Date:		October 2024
>> +Contact:	Rodolfo Giometti <giometti@...eenne.com>
>> +Description:
>> +		This read-only file contains the current time stored into the
>> +		generator clock as two integers representing the current time
>> +		seconds and nanoseconds.
> 
> Trailing whitespace, please always run checkpatch.pl.

Fixed.

Ciao,

Rodolfo

-- 
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