From: lakshmi.sowjanya.d@intel.com
To: tglx@linutronix.de, jstultz@google.com, giometti@enneenne.com,
corbet@lwn.net, linux-kernel@vger.kernel.org
Cc: christopher.s.hall@intel.com, subramanian.mohan@intel.com,
lakshmi.sowjanya.d@intel.com, linux-doc@vger.kernel.org,
netdev@vger.kernel.org, pandith.n@intel.com, x86@kernel.org,
eddie.dong@intel.com, linux-sound@vger.kernel.org,
alexandre.torgue@foss.st.com, peter.hilber@opensynergy.com,
joabreu@synopsys.com, intel-wired-lan@lists.osuosl.org,
mcoquelin.stm32@gmail.com, thejesh.reddy.t.r@intel.com,
perex@perex.cz, anthony.l.nguyen@intel.com,
andriy.shevchenko@linux.intel.com, davem@davemloft.net
Subject: [Intel-wired-lan] [PATCH v6 00/11] Add support for Intel PPS Generator
Date: Wed, 10 Apr 2024 17:18:17 +0530 [thread overview]
Message-ID: <20240410114828.25581-1-lakshmi.sowjanya.d@intel.com> (raw)
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 base clock properties in clocksource structure
Patch 2 adds function to convert realtime to base clock
Patch 3 - 7 removes reference to convert_art_to_tsc function across
drivers
Patch 8 removes the convert art to tsc functions which are no longer
used
Patch 9 adds the pps(pulse per second) generator tio driver to the pps
subsystem.
Patch 10 documentation and usage of the pps tio generator module.
Patch 11 includes documentation for sysfs interface.
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 diable hardware
accordingly.
Lakshmi Sowjanya D (6):
x86/tsc: Add base clock properties in clocksource structure
x86/tsc: Remove art to tsc conversion functions which are obsolete
timekeeping: Add function to convert realtime to base clock
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
Thomas Gleixner (5):
e1000e: remove convert_art_to_tsc()
igc: remove convert_art_to_tsc()
stmmac: intel: remove convert_art_to_tsc()
ALSA: hda: remove convert_art_to_tsc()
ice/ptp: remove convert_art_to_tsc()
.../ABI/testing/sysfs-platform-pps-tio | 7 +
Documentation/driver-api/pps.rst | 22 ++
MAINTAINERS | 1 +
arch/x86/include/asm/tsc.h | 3 -
arch/x86/kernel/tsc.c | 92 ++-----
drivers/net/ethernet/intel/e1000e/ptp.c | 3 +-
drivers/net/ethernet/intel/ice/ice_ptp.c | 3 +-
drivers/net/ethernet/intel/igc/igc_ptp.c | 6 +-
.../net/ethernet/stmicro/stmmac/dwmac-intel.c | 3 +-
drivers/pps/generators/Kconfig | 16 ++
drivers/pps/generators/Makefile | 1 +
drivers/pps/generators/pps_gen_tio.c | 258 ++++++++++++++++++
include/linux/clocksource.h | 27 ++
include/linux/clocksource_ids.h | 1 +
include/linux/timekeeping.h | 6 +
kernel/time/timekeeping.c | 107 +++++++-
sound/pci/hda/hda_controller.c | 3 +-
17 files changed, 476 insertions(+), 83 deletions(-)
create mode 100644 Documentation/ABI/testing/sysfs-platform-pps-tio
create mode 100644 drivers/pps/generators/pps_gen_tio.c
--
2.35.3
next reply other threads:[~2024-04-10 11:48 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-10 11:48 lakshmi.sowjanya.d [this message]
2024-04-10 11:48 ` [Intel-wired-lan] [PATCH v6 01/11] x86/tsc: Add base clock properties in clocksource structure lakshmi.sowjanya.d
2024-04-10 21:20 ` Thomas Gleixner
2024-04-16 10:10 ` D, Lakshmi Sowjanya
2024-04-10 21:32 ` Thomas Gleixner
2024-04-16 10:11 ` D, Lakshmi Sowjanya
2024-04-10 11:48 ` [Intel-wired-lan] [PATCH v6 02/11] e1000e: remove convert_art_to_tsc() lakshmi.sowjanya.d
2024-04-10 21:42 ` Thomas Gleixner
2024-04-10 11:48 ` [Intel-wired-lan] [PATCH v6 03/11] igc: " lakshmi.sowjanya.d
2024-04-10 11:48 ` [Intel-wired-lan] [PATCH v6 04/11] stmmac: intel: " lakshmi.sowjanya.d
2024-04-10 11:48 ` [Intel-wired-lan] [PATCH v6 05/11] ALSA: hda: " lakshmi.sowjanya.d
2024-04-10 11:48 ` [Intel-wired-lan] [PATCH v6 06/11] ice/ptp: " lakshmi.sowjanya.d
2024-04-10 11:48 ` [Intel-wired-lan] [PATCH v6 07/11] x86/tsc: Remove art to tsc conversion functions which are obsolete lakshmi.sowjanya.d
2024-04-10 11:48 ` [Intel-wired-lan] [PATCH v6 08/11] timekeeping: Add function to convert realtime to base clock lakshmi.sowjanya.d
2024-04-10 22:15 ` Thomas Gleixner
2024-04-16 10:17 ` D, Lakshmi Sowjanya
2024-04-10 11:48 ` [Intel-wired-lan] [PATCH v6 09/11] pps: generators: Add PPS Generator TIO Driver lakshmi.sowjanya.d
2024-04-10 22:28 ` Thomas Gleixner
2024-04-16 10:19 ` D, Lakshmi Sowjanya
2024-04-10 11:48 ` [Intel-wired-lan] [PATCH v6 10/11] Documentation: driver-api: pps: Add Intel Timed I/O PPS generator lakshmi.sowjanya.d
2024-04-10 11:48 ` [Intel-wired-lan] [PATCH v6 11/11] ABI: pps: Add ABI documentation for Intel TIO lakshmi.sowjanya.d
2024-04-10 13:59 ` Andy Shevchenko
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