From nobody Thu Feb 12 15:50:55 2026 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.9]) (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 232C1286A8; Wed, 12 Jun 2024 03:54:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.9 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718164454; cv=none; b=hFxh5SwabY7jDq/mPIubVQk8ABOId5jH3G1Sj7Fs4/Tp+VUhjVWXLpBys60EZlk4tg4HCoZDJlnCsSKtJoKNIZcHABPVUMEUBRpQNvG1IErNBuGW5zi+qegHpPErdyz8sAkap+U/LRqNpR6btx+Gl6YG8GRLnj1xmFx1t+fGTd4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718164454; c=relaxed/simple; bh=bivqRNthuRrhiu9l+tfLYSHdvbOw1MUw9EiQZxQ84PY=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=u0gbhhs4Y7EC+aX9v/D66aLCSNENEu+umqMnPaknYCQxbSmbdrRw5jb0cZDCNdGHolUZ/Pb5g9BgvD/JFX84my2jVP6ayFptYQPA/ahC3JhzgXnJffy/TcM8q5dngB6i5fFHJqt41durS4k8L0Ky0FMWufkZn4bo655cNUItbBc= 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=BJHTFW/6; arc=none smtp.client-ip=198.175.65.9 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="BJHTFW/6" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1718164452; x=1749700452; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=bivqRNthuRrhiu9l+tfLYSHdvbOw1MUw9EiQZxQ84PY=; b=BJHTFW/6tTI/OyceWy+kxLwmO0jJQfXV1dWv2+R8lcCoAZObS6PzbQR9 5DXcFrY+RjUDCY4PYUQqx/3sogMvm6NERxZL7B6M5OJ2IJlcBTYldihMt NKTkGw3CV5RfDwp/nvwvnElV9KooPXYy8e+DFBFdwWUFp/PhNJYObD1Q9 kE5vdQ+O2LitpyceShncN/zwzEe5faAaEQ9BDznGm3cZrS/nQ8L1NGbC0 eY6zPCHVFmp6Zwe1pe5JJ9aGKLv2R3P1NVoU0PCgcCCW18ApkNsMZpSLl AOzvl+FsXTjV8z6Mh0YTren5haTnnWLFS/7IUHz3hAhqi3Sm6eNpKTMbx Q==; X-CSE-ConnectionGUID: 1d5+CItlTLiagrLxn+oFkQ== X-CSE-MsgGUID: VuMhyoKVQqCeU0S/XPsfxA== X-IronPort-AV: E=McAfee;i="6600,9927,11100"; a="37433749" X-IronPort-AV: E=Sophos;i="6.08,232,1712646000"; d="scan'208";a="37433749" Received: from fmviesa009.fm.intel.com ([10.60.135.149]) by orvoesa101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Jun 2024 20:54:11 -0700 X-CSE-ConnectionGUID: zsV2O8ztT6W34B88zsQXEA== X-CSE-MsgGUID: YDkcNxk2R7e1D08QS9jxWg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.08,232,1712646000"; d="scan'208";a="39758576" Received: from inlubt0316.iind.intel.com ([10.191.20.213]) by fmviesa009.fm.intel.com with ESMTP; 11 Jun 2024 20:54:07 -0700 From: lakshmi.sowjanya.d@intel.com 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, eddie.dong@intel.com, christopher.s.hall@intel.com, pandith.n@intel.com, subramanian.mohan@intel.com, thejesh.reddy.t.r@intel.com, lakshmi.sowjanya.d@intel.com Subject: [PATCH v10 2/3] Documentation: driver-api: pps: Add Intel Timed I/O PPS generator Date: Wed, 12 Jun 2024 09:23:58 +0530 Message-Id: <20240612035359.7307-3-lakshmi.sowjanya.d@intel.com> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20240612035359.7307-1-lakshmi.sowjanya.d@intel.com> References: <20240612035359.7307-1-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 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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 | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/Documentation/driver-api/pps.rst b/Documentation/driver-api/pp= s.rst index 78dded03e5d8..75f7b094f963 100644 --- a/Documentation/driver-api/pps.rst +++ b/Documentation/driver-api/pps.rst @@ -246,3 +246,27 @@ delay between assert and clear edge as small as possib= le 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 sign= al +is generated with a precision of ~20 nanoseconds. The generated PPS signal +is used to synchronize an external device with system clock. For example, +it can be used to share your clock with a device that receives PPS signal, +generated by Timed I/O device. There are dedicated Timed I/O pins to deliv= er +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 --=20 2.35.3