From patchwork Wed Feb 7 06:08:53 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: 197759 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a05:7301:168b:b0:106:860b:bbdd with SMTP id ma11csp2031964dyb; Tue, 6 Feb 2024 22:13:32 -0800 (PST) X-Google-Smtp-Source: AGHT+IGldXrWOa61VbvtwxkQchtBHT877VXw6UyDQciTa6nNqKvvqqaGCv2oB8iX4PzDh6SwbcRl X-Received: by 2002:a2e:9155:0:b0:2d0:5543:dcd3 with SMTP id q21-20020a2e9155000000b002d05543dcd3mr3605996ljg.3.1707286411930; Tue, 06 Feb 2024 22:13:31 -0800 (PST) ARC-Seal: i=2; a=rsa-sha256; t=1707286411; cv=pass; d=google.com; s=arc-20160816; b=ND2FU0dAkDnvojhlV4O/3Z4q+eaoHABdeyD/2iP/RT4bosxtnqASPqV7OfMUjPlHU/ 92nqiq5J8cXP3L+Qz4svcPoo4r7c4F8uv6GlUgt/yqPlAtfBBBzgpg9DIXhblUHRLoye RtcvxlAGWJ/tkWfGdPjwRclas9j8fqVbCuomztBApcjhyKcR0ouLZ6IDxVK7Aq778XnA Fa1r68JRxmnpEjxj19Z7GVFpgvT3jwEB9uhmlyslIAWiZqb0QycqUwqnUtKUy+IpUcw4 b2p5e5N11DaIAyqRriX3FnEjGHBVWP//IJGpfWpMZjcVH0HoYhgre6VuaR2fqWXof4/5 C2qw== ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=content-transfer-encoding:mime-version:list-unsubscribe :list-subscribe:list-id:precedence:references:in-reply-to:message-id :date:subject:cc:to:from:dkim-signature; bh=cv1lpDGOlJtPMI8kmqsIKcuLSVOH//YyBhXLAva2+rk=; fh=mPIFfM1zNHEnjHX4vcfmwMyxUtPPUIqMMcRf1q+bh94=; b=LENFR2HcCSDJAeF3mJFZ3HJLC5jGoEXipvx4lQtQcMkaNJ+SxBhLwPW76WRpPmDzx5 mVFwDV/OA2m2lrnDE5AhXR3LY1HMfMivfcCzAOfqmYkHJ0p1PtSvGloAYHhN7+X5oQrL ogKPDR/L3YhuOi1Koe132K3mSkatvMcKw2dUmQxQ/sB2adE4AYubAE/syFARDeY8Yvkm AkL+ER/CtN1SPtXYQYWXuzSxO3+I8fPshJH8vvD9atzJxP14c2JfUyXPRmKdJbt8ChmL iLjLo7QYIXI8jZFAQK01TLsfXougjLyt+7csJuaGP6tMS2c1D9Ca+8IX7qbGvx5is+oD BYOw==; dara=google.com ARC-Authentication-Results: i=2; mx.google.com; dkim=pass header.i=@intel.com header.s=Intel header.b=hNBTfKVH; arc=pass (i=1 spf=pass spfdomain=intel.com dkim=pass dkdomain=intel.com dmarc=pass fromdomain=intel.com); spf=pass (google.com: domain of linux-kernel+bounces-56003-ouuuleilei=gmail.com@vger.kernel.org designates 2604:1380:4601:e00::3 as permitted sender) smtp.mailfrom="linux-kernel+bounces-56003-ouuuleilei=gmail.com@vger.kernel.org"; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=intel.com X-Forwarded-Encrypted: i=2; AJvYcCU1fDm2j1utgZsKcHSGR44ZL/rgs8gPcoCtT8W+bDWUGS99HX8WtQbcxCOlaQzSZPIte3KRT2b23konrpyQtYBd3fGWwQ== Received: from am.mirrors.kernel.org (am.mirrors.kernel.org. [2604:1380:4601:e00::3]) by mx.google.com with ESMTPS id f24-20020a05640214d800b0056007f1ac8esi441355edx.326.2024.02.06.22.13.31 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 06 Feb 2024 22:13:31 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel+bounces-56003-ouuuleilei=gmail.com@vger.kernel.org designates 2604:1380:4601:e00::3 as permitted sender) client-ip=2604:1380:4601:e00::3; Authentication-Results: mx.google.com; dkim=pass header.i=@intel.com header.s=Intel header.b=hNBTfKVH; arc=pass (i=1 spf=pass spfdomain=intel.com dkim=pass dkdomain=intel.com dmarc=pass fromdomain=intel.com); spf=pass (google.com: domain of linux-kernel+bounces-56003-ouuuleilei=gmail.com@vger.kernel.org designates 2604:1380:4601:e00::3 as permitted sender) smtp.mailfrom="linux-kernel+bounces-56003-ouuuleilei=gmail.com@vger.kernel.org"; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=intel.com Received: from smtp.subspace.kernel.org (wormhole.subspace.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by am.mirrors.kernel.org (Postfix) with ESMTPS id 87B921F26600 for ; Wed, 7 Feb 2024 06:13:31 +0000 (UTC) Received: from localhost.localdomain (localhost.localdomain [127.0.0.1]) by smtp.subspace.kernel.org (Postfix) with ESMTP id A877E225D6; Wed, 7 Feb 2024 06:10:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="hNBTfKVH" 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 5931A23761; Wed, 7 Feb 2024 06:10:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.55.52.88 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707286212; cv=none; b=cqVI9p33mp0COpFQg0D5tmqVSNmL+1hA/rqYGcOiCb8VBpFeOK36jbbSVIRV27Jd1gmItu7HNJkB22uzYvgTRxZ8P9C7oiFy3RhNFGE5vFsg/ujvX9y0r+PWJ3HQwCow6VaFKjoN6tXO6bbS39zFPi2pwHupR+jBHtKGegStvZQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707286212; c=relaxed/simple; bh=6PS4+2Ywv1DMIM5u9+tNfbsYVKa0PISW1H4pAS3IZH0=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=U9TtldAEt/WPMHRE4ysL8UJeSk7+VHujxAmTxbNvOo8Ox1OXTDXrTL3b3QTghefEE1adhkElP5Q5uOtNHPojhTHjjfdU5JFhN7BAGT5ND+DRYAHnHg4kjpiG60nTPd8LSbrXBHuwsX48QZS/laHTqSAkbYkltXGr+M0wTW/B/ZI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=hNBTfKVH; arc=none smtp.client-ip=192.55.52.88 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 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1707286210; x=1738822210; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=6PS4+2Ywv1DMIM5u9+tNfbsYVKa0PISW1H4pAS3IZH0=; b=hNBTfKVHiOQvJvGJmtLGzCRM+Z7ooOQVcC8L6+4jyuvlCKrPXAFpyDmD 7kLT032VSW9S+pZ8mPBBVkH7/Uot52VmmottkKGSHMHSzcH7QWH7gsJuD YXskFrgWrf+1OnrPL68iuRRa4aiYbwcbZArqGAEAkvRamGcGRGHWDGkuk rIZipmyKLLC2XHpFhrIHBUrw5SeCYHJfff2hnhZcxd5b3i+JLFKt+Eb+u X04ve7zoOU5Q6609wTCb0ZI7MF7u6gzvNdsvdTH/IQCZbBWTPPHyXOjsP zxeAkd5qekINTytSFBe9cl0g30ZJV1ymK6gBJFziAPiTemH7W8Wm866eP g==; X-IronPort-AV: E=McAfee;i="6600,9927,10976"; a="436054098" X-IronPort-AV: E=Sophos;i="6.05,250,1701158400"; d="scan'208";a="436054098" Received: from fmviesa004.fm.intel.com ([10.60.135.144]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Feb 2024 22:10:09 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.05,250,1701158400"; d="scan'208";a="5849933" Received: from inlubt0316.iind.intel.com ([10.191.20.213]) by fmviesa004.fm.intel.com with ESMTP; 06 Feb 2024 22:10:03 -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, peter.hilber@opensynergy.com, pandith.n@intel.com, mallikarjunappa.sangannavar@intel.com, subramanian.mohan@intel.com, thejesh.reddy.t.r@intel.com, lakshmi.sowjanya.d@intel.com Subject: [PATCH v4 10/11] Documentation: driver-api: pps: Add Intel Timed I/O PPS generator Date: Wed, 7 Feb 2024 11:38:53 +0530 Message-Id: <20240207060854.6524-11-lakshmi.sowjanya.d@intel.com> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20240207060854.6524-1-lakshmi.sowjanya.d@intel.com> References: <20240207060854.6524-1-lakshmi.sowjanya.d@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1790219556709419413 X-GMAIL-MSGID: 1790219556709419413 From: Lakshmi Sowjanya D Add Intel Timed I/O PPS usage instructions. Co-developed-by: Pandith N Signed-off-by: Pandith N Signed-off-by: Lakshmi Sowjanya D Reviewed-by: Andy Shevchenko --- Documentation/driver-api/pps.rst | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/Documentation/driver-api/pps.rst b/Documentation/driver-api/pps.rst index 78dded03e5d8..52a6d5faf885 100644 --- a/Documentation/driver-api/pps.rst +++ b/Documentation/driver-api/pps.rst @@ -246,3 +246,25 @@ delay between assert and clear edge as small as possible to reduce system latencies. But if it is too small slave won't be able to capture clear edge transition. The default of 30us should be good enough in most situations. The delay can be selected using 'delay' pps_gen_parport module parameter. + + +Intel Timed I/O PPS signal generator +------------------------------------ + +Intel Timed I/O is a high precision device, present on 2019 and newer Intel +CPUs, that can generate PPS signals. + +Timed I/O and system time are both driven by same hardware clock. The signal +is generated with a precision of ~20 nanoseconds. The generated PPS signal +is used to synchronize an external device with system clock. For example, +share your clock with a device that receives PPS signal, generated by +Timed I/O device. There are dedicated Timed I/O pins to deliver the PPS signal +to an external device. + +Usage of Intel Timed I/O as PPS generator: + +Start generating PPS signal:: + $echo 1 > /sys/devices/platform/INTCxxxx\:00/enable + +Stop generating PPS signal:: + $echo 0 > /sys/devices/platform/INTCxxxx\:00/enable