From patchwork Mon May 13 10:38:12 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: 13663303 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.8]) (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 F0B5014B06E; Mon, 13 May 2024 10:39:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.8 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715596774; cv=none; b=BgZjsGcys2lbV5dh6U3oXIa4HEw3sMr9DOdfSF0FMSPC5/Tg3dspgreLkNAtQisxjA9TtROVJtTeNIsB/2f/zVTLCewcXaB/zKRHfjfg1NvNcQX2AF9DwBChYoPFp9tFtgsJf16c8qtVGYKX5KQaLFyjBNXR4oobQ7CFG8OviA8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715596774; c=relaxed/simple; bh=9iwioP7RAGt6CZjyiP2VZXazdAn5HXvP+jiooI94v+E=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=GQkpSfPPsjyHY3m46onhAeFsDQD5c9pqsflNnBl932vwPyou088EG8kEDukNiEGcpvg3Q09DBrNE6ILwnnzETazXa8JJWvM9Q+5n+A8UO4o59QJw2/51Ta1Yy1U4ZVIw4vr2zt9u0BO6telJ4oB2xmSrsIoxg+CpEi3yF6ELqT4= 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=jEPX+Xju; arc=none smtp.client-ip=192.198.163.8 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="jEPX+Xju" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1715596773; x=1747132773; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=9iwioP7RAGt6CZjyiP2VZXazdAn5HXvP+jiooI94v+E=; b=jEPX+XjuDQaQ8U83tr9lZ3gLnAAVydRHiu/5VU8ZBrZjR/JHE1V9QgWr 6b/TY+LEWWvKV1dJryPduZBRsdMB7IJ/2Ng79HgrHTEPEyXwcoaFSc1uh VCJP4c+MAqQkj1nVrBqVUbE6P1mwsbbn5Ji5Ez7tMr8H7zbwA1C+zARJV 64UZRZTZ7hHVjjm6SGLsFYpq/iF8IMk37n9OK5u+ln9hskWN4hhUOQ4iP WZc8eXBUxmy7oJ6bs3A3jGsIFjKr8TjTAKE3nRWWpuAocDLC3RiMtnVjX ZsR+EL5UNJczGWHAaCSW8XbejZ8+Pu9+iSv7/R6M+DFfrcgdXYHhQ4HmC g==; X-CSE-ConnectionGUID: FWBdrBjkSlGJnVo96MjLRg== X-CSE-MsgGUID: v6wOUrC+QdSMYeaN0cd2eA== X-IronPort-AV: E=McAfee;i="6600,9927,11071"; a="29039165" X-IronPort-AV: E=Sophos;i="6.08,158,1712646000"; d="scan'208";a="29039165" Received: from fmviesa001.fm.intel.com ([10.60.135.141]) by fmvoesa102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 May 2024 03:39:31 -0700 X-CSE-ConnectionGUID: YcPM5iW/QQyTmMhJEdPLPg== X-CSE-MsgGUID: v5twAhKHQtu1OQuEE0slSA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.08,158,1712646000"; d="scan'208";a="61481873" Received: from inlubt0316.iind.intel.com ([10.191.20.213]) by fmviesa001.fm.intel.com with ESMTP; 13 May 2024 03:39:25 -0700 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, subramanian.mohan@intel.com, thejesh.reddy.t.r@intel.com, lakshmi.sowjanya.d@intel.com Subject: [PATCH v8 11/12] Documentation: driver-api: pps: Add Intel Timed I/O PPS generator Date: Mon, 13 May 2024 16:08:12 +0530 Message-Id: <20240513103813.5666-12-lakshmi.sowjanya.d@intel.com> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20240513103813.5666-1-lakshmi.sowjanya.d@intel.com> References: <20240513103813.5666-1-lakshmi.sowjanya.d@intel.com> Precedence: bulk X-Mailing-List: linux-sound@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 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 Acked-by: Rodolfo Giometti --- 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