linux-kernel - Re: [V3 3/4] Documentation pps.rst: add PPS generators documentation

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <Zy3m7qO81OP4DHAF@archie.me>
Date: Fri, 8 Nov 2024 17:24:46 +0700
From: Bagas Sanjaya <bagasdotme@...il.com>
To: Rodolfo Giometti <giometti@...eenne.com>, linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: Andrew Morton <akpm@...ux-foundation.org>, Greg KH <greg@...ah.com>,
	corbet@....net, Hall Christopher S <christopher.s.hall@...el.com>,
	Mohan Subramanian <subramanian.mohan@...el.com>, tglx@...utronix.de,
	Andy Shevchenko <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>,
	Randy Dunlap <rdunlap@...radead.org>
Subject: Re: [V3 3/4] Documentation pps.rst: add PPS generators documentation

On Fri, Nov 08, 2024 at 08:31:14AM +0100, Rodolfo Giometti wrote:
> diff --git a/Documentation/driver-api/pps.rst b/Documentation/driver-api/pps.rst
> index 78dded03e5d8..71ad04c82d6c 100644
> --- a/Documentation/driver-api/pps.rst
> +++ b/Documentation/driver-api/pps.rst
> @@ -202,6 +202,46 @@ Sometimes one needs to be able not only to catch PPS signals but to produce
>  them also. For example, running a distributed simulation, which requires
>  computers' clock to be synchronized very tightly.
>  
> +To do so the class pps-gen has been added. PPS generators can be
> +registered in the kernel by defining a struct pps_gen_source_info as
> +follows::
> +
> +    static struct pps_gen_source_info pps_gen_dummy_info = {
> +            .name                   = "dummy",
> +            .use_system_clock       = true,
> +            .get_time               = pps_gen_dummy_get_time,
> +            .enable                 = pps_gen_dummy_enable,
> +    };
> +
> +Where the use_system_clock states if the generator uses the system
> +clock to generate its pulses, or they are from a peripheral device
> +clock. Method get_time() is used to query the time stored into the
> +generator clock, while the method enable() is used to enable or
> +disable the PPS pulse generation.
> +
> +Then calling the function pps_gen_register_source() in your
> +initialization routine as follows creates a new generator in the
> +system::
> +
> +    pps_gen = pps_gen_register_source(&pps_gen_dummy_info);
> +
> +Generators SYSFS support
> +------------------------
> +
> +If the SYSFS filesystem is enabled in the kernel it provides a new class::
> +
> +    $ ls /sys/class/pps-gen/
> +    pps-gen0/  pps-gen1/  pps-gen2/
> +
> +Every directory is the ID of a PPS generator defined in the system and
> +inside of it you find several files::
> +
> +    $ ls -F /sys/class/pps-gen/pps-gen0/
> +    dev  enable  name  power/  subsystem@  system  time  uevent
> +
> +To enable the PPS signal generation you can use the command below::
> +
> +    $ echo 1 > /sys/class/pps-gen/pps-gen0/enable
>  
>  Parallel port generator
>  ------------------------

Looks good, thanks!

Reviewed-by: Bagas Sanjaya <bagasdotme@...il.com>

-- 
An old man doll... just what I always wanted! - Clara

Download attachment "signature.asc" of type "application/pgp-signature" (229 bytes)