linux-kernel - Re: [RFC 1/3] drivers pps: add PPS generators support

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

Message-ID: <d8e9b91f-65fb-4b71-b586-998fbf914b0a@enneenne.com>
Date: Wed, 9 Oct 2024 10:48:37 +0200
From: Rodolfo Giometti <giometti@...eenne.com>
To: "Hall, Christopher S" <christopher.s.hall@...el.com>,
 "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>, Greg KH <greg@...ah.com>,
 "corbet@....net" <corbet@....net>,
 "Mohan, Subramanian" <subramanian.mohan@...el.com>,
 "tglx@...utronix.de" <tglx@...utronix.de>,
 "andriy.shevchenko@...ux.intel.com" <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 1/3] drivers pps: add PPS generators support

On 09/10/24 04:49, Hall, Christopher S wrote:
> Hi Rudolfo,
> 
>> -----Original Message-----
>> From: Rodolfo Giometti <giometti@...eenne.com>
>> Sent: Tuesday, October 08, 2024 6:51 AM
>> To: linux-doc@...r.kernel.org; linux-kernel@...r.kernel.org
> 
>> 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.
>>
>> This patch adds PPS generators class in order to have a well-defined
>> interface for these devices.
>>
>> Signed-off-by: Rodolfo Giometti <giometti@...eenne.com>
>> ---
>>   drivers/pps/Makefile                   |   3 +-
>>   drivers/pps/generators/Kconfig         |  19 +-
>>   drivers/pps/generators/Makefile        |   4 +
>>   drivers/pps/generators/pps_gen-dummy.c |  83 ++++++++
>>   drivers/pps/generators/pps_gen.c       | 283 +++++++++++++++++++++++++
>>   drivers/pps/generators/sysfs.c         |  89 ++++++++
>>   include/linux/pps_gen_kernel.h         |  57 +++++
>>   include/uapi/linux/pps_gen.h           |  35 +++
>>   8 files changed, 571 insertions(+), 2 deletions(-)
>>   create mode 100644 drivers/pps/generators/pps_gen-dummy.c
>>   create mode 100644 drivers/pps/generators/pps_gen.c
>>   create mode 100644 drivers/pps/generators/sysfs.c
>>   create mode 100644 include/linux/pps_gen_kernel.h
>>   create mode 100644 include/uapi/linux/pps_gen.h
> 
> This looks pretty good to me. I would like to see an alarm callback. We are able
> to detect a missed event and rather than stopping inexplicably or writing to the
> system log, it would be better to be able to notify an application directly.
> 
> Off the top of my head, something like:
> 
> void pps_gen_alarm(pps_gen_device *pps_gen) {
> 	pps_gen->alarm = 1;
> 	sysfs_notify(pps_gen->dev->kobj, NULL, "alarm");
> }
> 
> The device is reset by disabling/enabling and this resets the alarm flag.
> 
> Could we add something like this?

Yes, of course. But it's better to provide a proper patch against my patchset V1 
(I'm going to anticipate them to you shortly), since I'm not sure to understand 
what you need.

Ciao,

Rodolfo

-- 
GNU/Linux Solutions                  e-mail: giometti@...eenne.com
Linux Device Driver                          giometti@...ux.it
Embedded Systems                     phone:  +39 349 2432127
UNIX programming