From: Lakshmi Sowjanya D <lakshmi.sowjanya.d@intel.com>

The goal of the PPS (Pulse Per Second) hardware/software is to generate a
signal from the system on a wire so that some third-party hardware can
observe that signal and judge how close the system's time is to another
system or piece of hardware.

Existing methods (like parallel ports) require software to flip a bit at
just the right time to create a PPS signal. Many things can prevent
software from doing this precisely. This (Timed I/O) method is better
because software only "arms" the hardware in advance and then depends on
the hardware to "fire" and flip the signal at just the right time.

To generate a PPS signal with this new hardware, the kernel wakes up
twice a second, once for 1->0 edge and other for the 0->1 edge. It does
this shortly (~10ms) before the actual change in the signal needs to be
made. It computes the TSC value at which edge will happen, convert to a
value hardware understands and program this value to Timed I/O hardware.
The actual edge transition happens without any further action from the
kernel.

The result here is a signal coming out of the system that is roughly
1,000 times more accurate than the old methods. If the system is heavily
loaded, the difference in accuracy is larger in old methods.

Application Interface:
The API to use Timed I/O is very simple. It is enabled and disabled by
writing a '1' or '0' value to the sysfs enable attribute associated with
the Timed I/O PPS device. Each Timed I/O pin is represented by a PPS
device. When enabled, a pulse-per-second (PPS) synchronized with the
system clock is continuously produced on the Timed I/O pin, otherwise it
is pulled low.

The Timed I/O signal on the motherboard is enabled in the BIOS setup.
Intel Advanced Menu -> PCH IO Configuration -> Timed I/O <Enable>

References:
https://en.wikipedia.org/wiki/Pulse-per-second_signal
https://drive.google.com/file/d/1vkBRRDuELmY8I3FlfOZaEBp-DxLW6t_V/view
https://youtu.be/JLUTT-lrDqw
 
Patch 1 adds the pps(pulse per second) generator tio driver to the pps
subsystem.
Patch 2 documentation and usage of the pps tio generator module.
Patch 3 includes documentation for sysfs interface.

These patches are based on the timers/core branch:
[1] https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/?h=timers/core
These changes are dependent on patches that are merged in [1].

Please help to review the changes.

Thanks in advance,
Sowjanya

Changes from v2:
 - Split patch 1 to remove the functions in later stages.
 - Include required headers in pps_gen_tio.

Changes from v3:
 - Corrections in Documentation.
 - Introducing non-RFC version of the patch series.

Changes from v4:
 - Setting id in ice_ptp
 - Modified conversion logic in convert_base_to_cs.
 - Included the usage of the APIs in the commit message of 2nd patch.

Changes from v5:
 - Change nsecs variable to use_nsecs.
 - Change order of 1&2 patches and modify the commit message.
 - Add sysfs abi file entry in MAINTAINERS file.
 - Add check to find if any event is missed and disable hardware
   accordingly.

Changes from v6:
 - Split patch 1 into 1&2 patches.
 - Add check for overflow in convert_ns_to_cs().
 - Refine commit messages.

Changes from v7:
 - Split the if condition and return error if current time exceeds
   expire time.
 - Update kernel version and month in ABI file.

Changes from v8:
 - Add function to enable Timed I/O.
 - Changed the updating of tio->enabled to a centralized place in
   disable and enable functions.

Changes from v9:
 - use tio->enabled instead of reading ctrl register.
 - change error code in enable_store to -ENODEV.

Lakshmi Sowjanya D (3):
  pps: generators: Add PPS Generator TIO Driver
  Documentation: driver-api: pps: Add Intel Timed I/O PPS generator
  ABI: pps: Add ABI documentation for Intel TIO

 .../ABI/testing/sysfs-platform-pps-tio        |   7 +
 Documentation/driver-api/pps.rst              |  24 ++
 MAINTAINERS                                   |   1 +
 drivers/pps/generators/Kconfig                |  16 ++
 drivers/pps/generators/Makefile               |   1 +
 drivers/pps/generators/pps_gen_tio.c          | 264 ++++++++++++++++++
 6 files changed, 313 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-platform-pps-tio
 create mode 100644 drivers/pps/generators/pps_gen_tio.c

-- 
2.35.3

On Wed, Jun 12, 2024 at 09:23:56AM +0530, lakshmi.sowjanya.d@intel.com wrote:
> From: Lakshmi Sowjanya D <lakshmi.sowjanya.d@intel.com>

Note, this email address is now bouncing, so that's not a good
recomendation for accepting a patch series :(

sorry,

greg k-h

On Wed, Jun 12, 2024 at 09:23:56AM +0530, lakshmi.sowjanya.d@intel.com wrote:
> From: Lakshmi Sowjanya D <lakshmi.sowjanya.d@intel.com>
> 
> The goal of the PPS (Pulse Per Second) hardware/software is to generate a
> signal from the system on a wire so that some third-party hardware can
> observe that signal and judge how close the system's time is to another
> system or piece of hardware.
> 
> Existing methods (like parallel ports) require software to flip a bit at
> just the right time to create a PPS signal. Many things can prevent
> software from doing this precisely. This (Timed I/O) method is better
> because software only "arms" the hardware in advance and then depends on
> the hardware to "fire" and flip the signal at just the right time.
> 
> To generate a PPS signal with this new hardware, the kernel wakes up
> twice a second, once for 1->0 edge and other for the 0->1 edge. It does
> this shortly (~10ms) before the actual change in the signal needs to be
> made. It computes the TSC value at which edge will happen, convert to a
> value hardware understands and program this value to Timed I/O hardware.
> The actual edge transition happens without any further action from the
> kernel.
> 
> The result here is a signal coming out of the system that is roughly
> 1,000 times more accurate than the old methods. If the system is heavily
> loaded, the difference in accuracy is larger in old methods.
> 
> Application Interface:
> The API to use Timed I/O is very simple. It is enabled and disabled by
> writing a '1' or '0' value to the sysfs enable attribute associated with
> the Timed I/O PPS device. Each Timed I/O pin is represented by a PPS
> device. When enabled, a pulse-per-second (PPS) synchronized with the
> system clock is continuously produced on the Timed I/O pin, otherwise it
> is pulled low.
> 
> The Timed I/O signal on the motherboard is enabled in the BIOS setup.
> Intel Advanced Menu -> PCH IO Configuration -> Timed I/O <Enable>
> 
> References:
> https://en.wikipedia.org/wiki/Pulse-per-second_signal
> https://drive.google.com/file/d/1vkBRRDuELmY8I3FlfOZaEBp-DxLW6t_V/view
> https://youtu.be/JLUTT-lrDqw
>  
> Patch 1 adds the pps(pulse per second) generator tio driver to the pps
> subsystem.
> Patch 2 documentation and usage of the pps tio generator module.
> Patch 3 includes documentation for sysfs interface.
> 
> These patches are based on the timers/core branch:
> [1] https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/?h=timers/core
> These changes are dependent on patches that are merged in [1].

This series now breaks the build due to api changes in 6.11-rc1.  Please
fix up and resend.

thanks,

greg k-h

Hi Greg,

> -----Original Message-----
> From: Greg KH <gregkh@linuxfoundation.org>
> Sent: Tuesday, August 13, 2024 1:46 PM
> To: lakshmi.sowjanya.d@intel.com
> Cc: tglx@linutronix.de; giometti@enneenne.com; corbet@lwn.net; linux-
> kernel@vger.kernel.org; linux-doc@vger.kernel.org;
> andriy.shevchenko@linux.intel.com; Dong, Eddie <eddie.dong@intel.com>;
> Hall, Christopher S <christopher.s.hall@intel.com>; N, Pandith
> <pandith.n@intel.com>; Mohan, Subramanian
> <subramanian.mohan@intel.com>; T R, Thejesh Reddy
> <thejesh.reddy.t.r@intel.com>
> Subject: Re: [PATCH v10 0/3] Add support for Intel PPS Generator
> 
> On Wed, Jun 12, 2024 at 09:23:56AM +0530, lakshmi.sowjanya.d@intel.com
> wrote:
> > From: Lakshmi Sowjanya D <lakshmi.sowjanya.d@intel.com>
> >
> > The goal of the PPS (Pulse Per Second) hardware/software is to
> > generate a signal from the system on a wire so that some third-party
> > hardware can observe that signal and judge how close the system's time
> > is to another system or piece of hardware.
> >
> > Existing methods (like parallel ports) require software to flip a bit
> > at just the right time to create a PPS signal. Many things can prevent
> > software from doing this precisely. This (Timed I/O) method is better
> > because software only "arms" the hardware in advance and then depends
> > on the hardware to "fire" and flip the signal at just the right time.
> >
> > To generate a PPS signal with this new hardware, the kernel wakes up
> > twice a second, once for 1->0 edge and other for the 0->1 edge. It
> > does this shortly (~10ms) before the actual change in the signal needs
> > to be made. It computes the TSC value at which edge will happen,
> > convert to a value hardware understands and program this value to Timed
> I/O hardware.
> > The actual edge transition happens without any further action from the
> > kernel.
> >
> > The result here is a signal coming out of the system that is roughly
> > 1,000 times more accurate than the old methods. If the system is
> > heavily loaded, the difference in accuracy is larger in old methods.
> >
> > Application Interface:
> > The API to use Timed I/O is very simple. It is enabled and disabled by
> > writing a '1' or '0' value to the sysfs enable attribute associated
> > with the Timed I/O PPS device. Each Timed I/O pin is represented by a
> > PPS device. When enabled, a pulse-per-second (PPS) synchronized with
> > the system clock is continuously produced on the Timed I/O pin,
> > otherwise it is pulled low.
> >
> > The Timed I/O signal on the motherboard is enabled in the BIOS setup.
> > Intel Advanced Menu -> PCH IO Configuration -> Timed I/O <Enable>
> >
> > References:
> > https://en.wikipedia.org/wiki/Pulse-per-second_signal
> > https://drive.google.com/file/d/1vkBRRDuELmY8I3FlfOZaEBp-
> DxLW6t_V/view
> > https://youtu.be/JLUTT-lrDqw
> >
> > Patch 1 adds the pps(pulse per second) generator tio driver to the pps
> > subsystem.
> > Patch 2 documentation and usage of the pps tio generator module.
> > Patch 3 includes documentation for sysfs interface.
> >
> > These patches are based on the timers/core branch:
> > [1]
> > https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/?h=timers/
> > core These changes are dependent on patches that are merged in [1].
> 
> This series now breaks the build due to api changes in 6.11-rc1.  Please fix up
> and resend.

Ok, will fix up the API changes  and resend the patch series.

> thanks,
> 
> greg k-h

Thanks,
Subbu

> -----Original Message-----
> From: D, Lakshmi Sowjanya <lakshmi.sowjanya.d@intel.com>
> Sent: Wednesday, June 12, 2024 9:24 AM
> To: tglx@linutronix.de; giometti@enneenne.com; corbet@lwn.net; linux-
> kernel@vger.kernel.org; linux-doc@vger.kernel.org
> Cc: gregkh@linuxfoundation.org; andriy.shevchenko@linux.intel.com; Dong,
> Eddie <eddie.dong@intel.com>; Hall, Christopher S
> <christopher.s.hall@intel.com>; N, Pandith <pandith.n@intel.com>; Mohan,
> Subramanian <subramanian.mohan@intel.com>; T R, Thejesh Reddy
> <thejesh.reddy.t.r@intel.com>; D, Lakshmi Sowjanya
> <lakshmi.sowjanya.d@intel.com>
> Subject: [PATCH v10 0/3] Add support for Intel PPS Generator
> 
> From: Lakshmi Sowjanya D <lakshmi.sowjanya.d@intel.com>
> 
> The goal of the PPS (Pulse Per Second) hardware/software is to generate a
> signal from the system on a wire so that some third-party hardware can observe
> that signal and judge how close the system's time is to another system or piece
> of hardware.
> 
> Existing methods (like parallel ports) require software to flip a bit at just the right
> time to create a PPS signal. Many things can prevent software from doing this
> precisely. This (Timed I/O) method is better because software only "arms" the
> hardware in advance and then depends on the hardware to "fire" and flip the
> signal at just the right time.
> 
> To generate a PPS signal with this new hardware, the kernel wakes up twice a
> second, once for 1->0 edge and other for the 0->1 edge. It does this shortly
> (~10ms) before the actual change in the signal needs to be made. It computes
> the TSC value at which edge will happen, convert to a value hardware
> understands and program this value to Timed I/O hardware.
> The actual edge transition happens without any further action from the kernel.
> 
> The result here is a signal coming out of the system that is roughly
> 1,000 times more accurate than the old methods. If the system is heavily loaded,
> the difference in accuracy is larger in old methods.
> 
> Application Interface:
> The API to use Timed I/O is very simple. It is enabled and disabled by writing a '1'
> or '0' value to the sysfs enable attribute associated with the Timed I/O PPS
> device. Each Timed I/O pin is represented by a PPS device. When enabled, a
> pulse-per-second (PPS) synchronized with the system clock is continuously
> produced on the Timed I/O pin, otherwise it is pulled low.
> 
> The Timed I/O signal on the motherboard is enabled in the BIOS setup.
> Intel Advanced Menu -> PCH IO Configuration -> Timed I/O <Enable>
> 
> References:
> https://en.wikipedia.org/wiki/Pulse-per-second_signal
> https://drive.google.com/file/d/1vkBRRDuELmY8I3FlfOZaEBp-DxLW6t_V/view
> https://youtu.be/JLUTT-lrDqw
> 
> Patch 1 adds the pps(pulse per second) generator tio driver to the pps
> subsystem.
> Patch 2 documentation and usage of the pps tio generator module.
> Patch 3 includes documentation for sysfs interface.
> 
> These patches are based on the timers/core branch:
> [1] https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/?h=timers/core
> These changes are dependent on patches that are merged in [1].
> 
> Please help to review the changes.
> 
> Thanks in advance,
> Sowjanya
> 
> Changes from v2:
>  - Split patch 1 to remove the functions in later stages.
>  - Include required headers in pps_gen_tio.
> 
> Changes from v3:
>  - Corrections in Documentation.
>  - Introducing non-RFC version of the patch series.
> 
> Changes from v4:
>  - Setting id in ice_ptp
>  - Modified conversion logic in convert_base_to_cs.
>  - Included the usage of the APIs in the commit message of 2nd patch.
> 
> Changes from v5:
>  - Change nsecs variable to use_nsecs.
>  - Change order of 1&2 patches and modify the commit message.
>  - Add sysfs abi file entry in MAINTAINERS file.
>  - Add check to find if any event is missed and disable hardware
>    accordingly.
> 
> Changes from v6:
>  - Split patch 1 into 1&2 patches.
>  - Add check for overflow in convert_ns_to_cs().
>  - Refine commit messages.
> 
> Changes from v7:
>  - Split the if condition and return error if current time exceeds
>    expire time.
>  - Update kernel version and month in ABI file.
> 
> Changes from v8:
>  - Add function to enable Timed I/O.
>  - Changed the updating of tio->enabled to a centralized place in
>    disable and enable functions.
> 
> Changes from v9:
>  - use tio->enabled instead of reading ctrl register.
>  - change error code in enable_store to -ENODEV.
> 
> Lakshmi Sowjanya D (3):
>   pps: generators: Add PPS Generator TIO Driver
>   Documentation: driver-api: pps: Add Intel Timed I/O PPS generator
>   ABI: pps: Add ABI documentation for Intel TIO
> 
>  .../ABI/testing/sysfs-platform-pps-tio        |   7 +
>  Documentation/driver-api/pps.rst              |  24 ++
>  MAINTAINERS                                   |   1 +
>  drivers/pps/generators/Kconfig                |  16 ++
>  drivers/pps/generators/Makefile               |   1 +
>  drivers/pps/generators/pps_gen_tio.c          | 264 ++++++++++++++++++
>  6 files changed, 313 insertions(+)
>  create mode 100644 Documentation/ABI/testing/sysfs-platform-pps-tio
>  create mode 100644 drivers/pps/generators/pps_gen_tio.c
> 
> --
> 2.35.3

Hi,

A gentle reminder for the review of the pps patchset.

Regards
Sowjanya

On 03/07/24 16:47, D, Lakshmi Sowjanya wrote:

[sbip]

>> Subject: [PATCH v10 0/3] Add support for Intel PPS Generator
>>
>> From: Lakshmi Sowjanya D <lakshmi.sowjanya.d@intel.com>
>>
>> The goal of the PPS (Pulse Per Second) hardware/software is to generate a
>> signal from the system on a wire so that some third-party hardware can observe
>> that signal and judge how close the system's time is to another system or piece
>> of hardware.

[snip]

> Hi,
> 
> A gentle reminder for the review of the pps patchset.

I already acked these patchset, didn't I? =8-o

Please let me know if I missed something.

Rodolfo

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

On Thu, Jul 04 2024 at 13:50, Rodolfo Giometti wrote:
> On 03/07/24 16:47, D, Lakshmi Sowjanya wrote:
>> 
>> A gentle reminder for the review of the pps patchset.
>
> I already acked these patchset, didn't I? =8-o
>
> Please let me know if I missed something.

Sorry, I missed that V10 posting. It's too late now.

Rodolfo, can you pick it up after rc1 for the next merge window. All
prerequisites should be in Linus tree then.

Thanks,

        tglx

On 15/07/24 10:06, Thomas Gleixner wrote:
> On Thu, Jul 04 2024 at 13:50, Rodolfo Giometti wrote:
>> On 03/07/24 16:47, D, Lakshmi Sowjanya wrote:
>>>
>>> A gentle reminder for the review of the pps patchset.
>>
>> I already acked these patchset, didn't I? =8-o
>>
>> Please let me know if I missed something.
> 
> Sorry, I missed that V10 posting. It's too late now.
> 
> Rodolfo, can you pick it up after rc1 for the next merge window. All
> prerequisites should be in Linus tree then.

LinuxPPS has no dedicated tree as other Linux subsystems. Usually I send my 
"Acked" to Greg Kroah-Hartman and Andrew Morton, and they push patches by 
themselves.

Ciao,

Rodolfo

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

Hello Rodolfo,

> From: Rodolfo Giometti <giometti@enneenne.com>
> Sent: Monday, July 15, 2024 2:37 AM

> Subject: Re: [PATCH v10 0/3] Add support for Intel PPS Generator
> 
> On 15/07/24 10:06, Thomas Gleixner wrote:
> > On Thu, Jul 04 2024 at 13:50, Rodolfo Giometti wrote:
> >> On 03/07/24 16:47, D, Lakshmi Sowjanya wrote:
> >>>
> >>> A gentle reminder for the review of the pps patchset.
> >>
> >> I already acked these patchset, didn't I? =8-o
> >>
> >> Please let me know if I missed something.
> >
> > Sorry, I missed that V10 posting. It's too late now.
> >
> > Rodolfo, can you pick it up after rc1 for the next merge window. All
> > prerequisites should be in Linus tree then.
> 
> LinuxPPS has no dedicated tree as other Linux subsystems. Usually I send my
> "Acked" to Greg Kroah-Hartman and Andrew Morton, and they push patches
> by
> themselves.

Is the PPS driver on track to be included in the 6.11 release candidate?

Thanks,
Chris

On 24/07/24 23:39, Hall, Christopher S wrote:
> Hello Rodolfo,
> 
>> From: Rodolfo Giometti <giometti@enneenne.com>
>> Sent: Monday, July 15, 2024 2:37 AM
> 
>> Subject: Re: [PATCH v10 0/3] Add support for Intel PPS Generator
>>
>> On 15/07/24 10:06, Thomas Gleixner wrote:
>>> On Thu, Jul 04 2024 at 13:50, Rodolfo Giometti wrote:
>>>> On 03/07/24 16:47, D, Lakshmi Sowjanya wrote:
>>>>>
>>>>> A gentle reminder for the review of the pps patchset.
>>>>
>>>> I already acked these patchset, didn't I? =8-o
>>>>
>>>> Please let me know if I missed something.
>>>
>>> Sorry, I missed that V10 posting. It's too late now.
>>>
>>> Rodolfo, can you pick it up after rc1 for the next merge window. All
>>> prerequisites should be in Linus tree then.
>>
>> LinuxPPS has no dedicated tree as other Linux subsystems. Usually I send my
>> "Acked" to Greg Kroah-Hartman and Andrew Morton, and they push patches
>> by
>> themselves.
> 
> Is the PPS driver on track to be included in the 6.11 release candidate?

I hope so! ^_^"

Unluckily the LinuxPPS is a minor subsystem with no dedicated tree, and 
inclusion is not under my control.

Ciao,

Rodolfo

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

On Thu, Jul 25, 2024 at 09:05:02AM +0200, Rodolfo Giometti wrote:
> On 24/07/24 23:39, Hall, Christopher S wrote:
> > Hello Rodolfo,
> > 
> > > From: Rodolfo Giometti <giometti@enneenne.com>
> > > Sent: Monday, July 15, 2024 2:37 AM
> > 
> > > Subject: Re: [PATCH v10 0/3] Add support for Intel PPS Generator
> > > 
> > > On 15/07/24 10:06, Thomas Gleixner wrote:
> > > > On Thu, Jul 04 2024 at 13:50, Rodolfo Giometti wrote:
> > > > > On 03/07/24 16:47, D, Lakshmi Sowjanya wrote:
> > > > > > 
> > > > > > A gentle reminder for the review of the pps patchset.
> > > > > 
> > > > > I already acked these patchset, didn't I? =8-o
> > > > > 
> > > > > Please let me know if I missed something.
> > > > 
> > > > Sorry, I missed that V10 posting. It's too late now.
> > > > 
> > > > Rodolfo, can you pick it up after rc1 for the next merge window. All
> > > > prerequisites should be in Linus tree then.
> > > 
> > > LinuxPPS has no dedicated tree as other Linux subsystems. Usually I send my
> > > "Acked" to Greg Kroah-Hartman and Andrew Morton, and they push patches
> > > by
> > > themselves.
> > 
> > Is the PPS driver on track to be included in the 6.11 release candidate?
> 
> I hope so! ^_^"

Are the patches in linux-next?  If so, what tree did they go through?
If not, they can't be merged into 6.11-rc1.

> Unluckily the LinuxPPS is a minor subsystem with no dedicated tree, and
> inclusion is not under my control.

I pick up many "smaller" driver subsystems all the time, I just have to
be asked to do so...

thanks,

greg k-h

On Thu, Jul 25 2024 at 09:09, gregkh@linuxfoundation.org wrote:
> Are the patches in linux-next?  If so, what tree did they go through?
> If not, they can't be merged into 6.11-rc1.

Sorry, I missed that last submission.

It has dependencies on the timers/core branch which got merged into
mainline in the current merge window. So if someone could have picked it
up that would have been me.

It's unfortunately too late now, so this can be picked up for 6.12 by
anyone without dependencies.

Thanks,

        tglx