From patchwork Wed Apr 10 11:48:27 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: 13624144 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.14]) (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 ED77115F3F7; Wed, 10 Apr 2024 11:49:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.14 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712749785; cv=none; b=mDvblD3CIrun9A3lepq+qnauJNdiuhnoaS0dvG7FyaQHPyBRjUsmM7Dgpd/2DKnw0rDhYHDjYLHijJNYvvT8wD8HbjkmLof0Sbq14oZH+Z4/v4KJjdPKLhBfnC8A4DQ01YIAahMhgTgPWZi4cbz5Z9o8n7yLmGdcoXKgZ/r8BKI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712749785; c=relaxed/simple; bh=9iwioP7RAGt6CZjyiP2VZXazdAn5HXvP+jiooI94v+E=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=YB7McNbquELV+yfATXOTo9mGT2hdmjtHRTgKjtRaM4cDAD7ANaw4/ECxn8t4f02snlzE/sKAaC0sG/gGAYGnG3m60+cDzHHOy0khjorXyRJJ0C+jHK6n3Glv0c7WRk/UtXydN1LkTUjcfzpuLnjjny0OTCV2T8cHddh3yqaYaeA= 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=TbtFC4vs; arc=none smtp.client-ip=198.175.65.14 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="TbtFC4vs" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1712749784; x=1744285784; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=9iwioP7RAGt6CZjyiP2VZXazdAn5HXvP+jiooI94v+E=; b=TbtFC4vs6Q3l444l9Gsw45ZgKxk6UgyXVWAwwNl5jXmyKy1rii5T6ViA HvVSy6DnVBBtR0qdxU+RoJeLbQiiWian5KAc6+UrBZ+3ThBm1BQ4i33f5 +gdhhv0dZM+2hvXqM01qarz8dpXjVSPfpyrZdyUu4o5xbxaXaHUct7GB3 h8ISb7nGAOxSkiMZ/DqLH5seHGICL1uVHQbeH/RZ9rVTMqb92koAzy5BA nJoiu8zPIu51vkSJOigLVZS8v57FzMMCY5YZc0CqJENGKzNWzo2UpUIvN IxRRYvy04KIztAamYolEKHcaLLBerVAvv4dLqItKYcd9CNZ+9Kt4dKOf5 g==; X-CSE-ConnectionGUID: dHihnkD2RHaKZ08DOzMWcg== X-CSE-MsgGUID: MvxUYidsQ8ej3RwWC3j3Ng== X-IronPort-AV: E=McAfee;i="6600,9927,11039"; a="11944228" X-IronPort-AV: E=Sophos;i="6.07,190,1708416000"; d="scan'208";a="11944228" Received: from fmviesa002.fm.intel.com ([10.60.135.142]) by orvoesa106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Apr 2024 04:49:43 -0700 X-CSE-ConnectionGUID: ZMxXGvjpTKqYYBzVgaXFdQ== X-CSE-MsgGUID: wruXKCixRWOi5eIjY0pPUA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.07,190,1708416000"; d="scan'208";a="43769356" Received: from inlubt0316.iind.intel.com ([10.191.20.213]) by fmviesa002.fm.intel.com with ESMTP; 10 Apr 2024 04:49:36 -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 v6 10/11] Documentation: driver-api: pps: Add Intel Timed I/O PPS generator Date: Wed, 10 Apr 2024 17:18:27 +0530 Message-Id: <20240410114828.25581-11-lakshmi.sowjanya.d@intel.com> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20240410114828.25581-1-lakshmi.sowjanya.d@intel.com> References: <20240410114828.25581-1-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