From patchwork Tue Apr 30 08:52:24 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: 13648507 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.13]) (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 08B6A1C2301; Tue, 30 Apr 2024 08:53:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.13 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714467231; cv=none; b=gHme2rDMH/KyQ0C8Mr/HD1VG3LDk9C3tNJ0qxtWflDE/1nSDCRWRWhVVxyQz1CRnkvgsxZ16lrZU6JBfGAJZlWBVSI6/CTjC11JaukB9RZyJ+G4jlZIQvWBYsQ71WP4vyqVDvkyXIH1UagbSy5vXYXSD2+YML6VSBm8KoMZTjso= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714467231; c=relaxed/simple; bh=9iwioP7RAGt6CZjyiP2VZXazdAn5HXvP+jiooI94v+E=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=hrpb01yXq8Kj4Pxy3tFTjPSg5Yw2WIBjJQXi/bw8tKTRRJCAZOpPs1Onn3Pal410ge+2z+JYcVgpO6ALV9pLtKrZHKz/ragfnFaQb0v61BPCLLWnBH4DDrF18na0nmpuF1FZUWCDlrLolSu5jgID7mH/XWn+TOmVSN72hDhq/gE= 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=ilddsNAS; arc=none smtp.client-ip=198.175.65.13 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="ilddsNAS" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1714467231; x=1746003231; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=9iwioP7RAGt6CZjyiP2VZXazdAn5HXvP+jiooI94v+E=; b=ilddsNASGTqKgMAhLxBG7TU5xtcuDxeYDyfohrts7MzDIZfyS6SOl9Tn C9Yvm/Wx4AOLKNtxTPeQilGmMKi63GPhn4D9aKM5kvQa4SDSJBcgQFDC4 WQhzOf8cIoBdbtxATC2FK3nAWf3Pk4irqhY1uQq4FgaLdT2jdIcL4zuPz Az6Nik5AaHSJSHjnUduv+oXCGWB1WS1fSxvtZMv3RvqJcrv8Z9RhpBN16 PrlmQkLg2KMJtUqfR0blagUUgR2uh4yNBhGrkiJZUZb0FX+N7q7F8mcVi Og9HUhHyK31ffADop0jnFQSGvz80VH3cdvIP8DbJK8F+Zq2SOPjU8t9d+ w==; X-CSE-ConnectionGUID: 4qP1F22QRpOuNyY7FL4PXA== X-CSE-MsgGUID: dMVhiFmBT2mS1OikJNgubQ== X-IronPort-AV: E=McAfee;i="6600,9927,11059"; a="21311537" X-IronPort-AV: E=Sophos;i="6.07,241,1708416000"; d="scan'208";a="21311537" Received: from orviesa007.jf.intel.com ([10.64.159.147]) by orvoesa105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Apr 2024 01:53:50 -0700 X-CSE-ConnectionGUID: 7HdIUzMYTBuEBbzXwK9Ssg== X-CSE-MsgGUID: CWG1FaSkRIOXsO4dIBuRYQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.07,241,1708416000"; d="scan'208";a="26891687" Received: from inlubt0316.iind.intel.com ([10.191.20.213]) by orviesa007.jf.intel.com with ESMTP; 30 Apr 2024 01:53:42 -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 v7 11/12] Documentation: driver-api: pps: Add Intel Timed I/O PPS generator Date: Tue, 30 Apr 2024 14:22:24 +0530 Message-Id: <20240430085225.18086-12-lakshmi.sowjanya.d@intel.com> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20240430085225.18086-1-lakshmi.sowjanya.d@intel.com> References: <20240430085225.18086-1-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