From patchwork Wed Jan 3 11:55:51 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "D, Lakshmi Sowjanya" X-Patchwork-Id: 13509948 Received: from mgamail.intel.com (mgamail.intel.com [192.55.52.88]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7903518E29; Wed, 3 Jan 2024 11:56:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="IH0YT9v+" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1704282970; x=1735818970; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=BJoEl3x1cNtCH48+TKJZcOqo9nUuIX3cSL+HLRYow5I=; b=IH0YT9v+1f2aKOrPlVJoKtopqPiijO6ioDyhsh3IqipQFyiURRn2Cko0 qRXRFXAs3OQF9QcHChQYTI+OmIuHfsMHToef3pFhcfw+d+x9NAAmP8p/E NtO+TUuO8a8ZpW8aK2LBlL0gLCtkd0upqpE5J8JAVyYlqSSIeZPoavU6L Q2gvja90WUDButy/rtlsbc2qzBhd+8BxwRhaqKm3YyLj7JzgIvO2mwGvv 8OrxkyKdzizmVNi6FYxJrBb48wFHjD7pIlwJRO34fuMgFpg9dFvvjc+2b BhwCUaq/khlv6qPOZOzue2zpeCxZbbqfCi2u6/4aocLC/IaYuO2nwUy+m g==; X-IronPort-AV: E=McAfee;i="6600,9927,10941"; a="428169393" X-IronPort-AV: E=Sophos;i="6.04,327,1695711600"; d="scan'208";a="428169393" Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Jan 2024 03:56:09 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10941"; a="1111348025" X-IronPort-AV: E=Sophos;i="6.04,327,1695711600"; d="scan'208";a="1111348025" Received: from inlubt0316.iind.intel.com ([10.191.20.213]) by fmsmga005.fm.intel.com with ESMTP; 03 Jan 2024 03:56:03 -0800 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: x86@kernel.org, netdev@vger.kernel.org, linux-doc@vger.kernel.org, intel-wired-lan@lists.osuosl.org, andriy.shevchenko@linux.intel.com, eddie.dong@intel.com, christopher.s.hall@intel.com, jesse.brandeburg@intel.com, davem@davemloft.net, alexandre.torgue@foss.st.com, joabreu@synopsys.com, mcoquelin.stm32@gmail.com, perex@perex.cz, linux-sound@vger.kernel.org, anthony.l.nguyen@intel.com, pandith.n@intel.com, mallikarjunappa.sangannavar@intel.com, thejesh.reddy.t.r@intel.com, lakshmi.sowjanya.d@intel.com Subject: [RFC PATCH v3 00/11] Add support for Intel PPS Generator Date: Wed, 3 Jan 2024 17:25:51 +0530 Message-Id: <20240103115602.19044-1-lakshmi.sowjanya.d@intel.com> X-Mailer: git-send-email 2.35.3 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-State: RFC From: Lakshmi Sowjanya D 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. Facebook and Google are the customers that use this feature. 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. This patchset is dependent on [1] 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. [1] https://lore.kernel.org/netdev/20231215220612.173603-2-peter.hilber@opensynergy.com/T/ 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. Lakshmi Sowjanya D (6): x86/tsc: Add base clock properties in clocksource structure timekeeping: Add function to convert realtime to base clock x86/tsc: Remove art to tsc conversion functions which are obsolete 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): e10002: 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 ++ arch/x86/include/asm/tsc.h | 3 - arch/x86/kernel/tsc.c | 94 ++----- drivers/net/ethernet/intel/e1000e/ptp.c | 3 +- drivers/net/ethernet/intel/ice/ice_ptp.c | 2 +- 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 | 245 ++++++++++++++++++ include/linux/clocksource.h | 27 ++ include/linux/clocksource_ids.h | 1 + include/linux/timekeeping.h | 6 + kernel/time/timekeeping.c | 112 +++++++- sound/pci/hda/hda_controller.c | 3 +- 16 files changed, 466 insertions(+), 85 deletions(-) create mode 100644 Documentation/ABI/testing/sysfs-platform-pps-tio create mode 100644 drivers/pps/generators/pps_gen_tio.c