From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A1544C49EAB for ; Fri, 25 Jun 2021 23:48:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 870CD61962 for ; Fri, 25 Jun 2021 23:48:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229996AbhFYXud (ORCPT ); Fri, 25 Jun 2021 19:50:33 -0400 Received: from mail-dm6nam08on2061.outbound.protection.outlook.com ([40.107.102.61]:57023 "EHLO NAM04-DM6-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S229933AbhFYXua (ORCPT ); Fri, 25 Jun 2021 19:50:30 -0400 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=bTkpRQefyqx54RLS0aRMdWJZg9UvxtS7HhjDmIbF5oeXD+XcvOIkmi6W2z7786qTg+dlVLn0nSNcOcpqwCBH0Zr3Z3gXfaFOLbQoQKDY8U3e5A57ajxO5GB7+1ID3TBdBzYh5As85F3PjTlw6JoEJIDSE6+FAbywzAywN7PmtBOY0tsONpceYPNihiRxJCqdS/Ipq5NWf44a6xEDM+U1HOeST+QxOaHX5kd5EZljo35sXVw5kIP6RWX/n+pmSZZjRiTMb+E8k11EdaZQE0bVr8Zj6IKkOhayrCfPZs43REkTvm0RwDPY7FN3ZL41okIx5rG3xQZrjfxcjFNSC11PUw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=gknGpml5gdzaoSbl72Yt4XpgyGP8DJ28L4UrnuZpZ6I=; b=khehv6wKJr3mFdMiEvB0NaxVMiIeds2M1WIm8P6YOznWHp1Od9k3Z9ZsowHUGZQvfLYYiK3hRoMegoUoqX6W1UQ0NVUfTWajn0clFelpoMUBlndjkpMBaB3lN4FDVbBPNX2Ft3xXZz/f6KjF/4NnyI5ux7DHL4vxSbAuMWABH0N1N6J2unoK4qT5VLVAwnfniExJ2HKhaAT2akav4OCGpSdtGBMfnrzvBe/J1RxmY/b7PE86BSgjA7N7thuQFWpmHO/lNnOPdPO0+vijf7mVXpip/zNIKkkQnJ4jgPVMvWs4WNepX8jmuvaFKzuuVCvUBLQb2DDkUhwZb9Q+eeeyUw== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass (sender ip is 216.228.112.35) smtp.rcpttodomain=gmail.com smtp.mailfrom=nvidia.com; dmarc=pass (p=none sp=none pct=100) action=none header.from=nvidia.com; dkim=none (message not signed); arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=Nvidia.com; s=selector2; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=gknGpml5gdzaoSbl72Yt4XpgyGP8DJ28L4UrnuZpZ6I=; b=KwXu/4RAZcdRYdahbuag36JrYVIW6of6wz8gytnMcv8cUROKj37vDERvrtsnnUMIHUYzRWI+mrjVdg/Tf06+agGeVx5ub05KTOatrLKGKm8HZE8DQ67dzp+hvoMALHwYpI6+b2HsJPpfXq+O/Zhxoj8k0SJEBrhLZoFaavRLuLehuA5qKF6uHfsAQLa4rZ9dBH2i2GYcCiLDOszuI/lU+yFc1Ux8pOKlbQmalcPMwUKnyMmtfvDOFp63MV9JOCyysMZaC/XSaIjdghly4m5qXUo/RkvJ6t9tePXF7C3FjRZAqfGz44qdL8fq40Oi0B/2vjd74Qg+ooMqOustaN4QKQ== Received: from BN8PR07CA0006.namprd07.prod.outlook.com (2603:10b6:408:ac::19) by BN8PR12MB3124.namprd12.prod.outlook.com (2603:10b6:408:41::12) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4264.20; Fri, 25 Jun 2021 23:48:07 +0000 Received: from BN8NAM11FT024.eop-nam11.prod.protection.outlook.com (2603:10b6:408:ac:cafe::9b) by BN8PR07CA0006.outlook.office365.com (2603:10b6:408:ac::19) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4264.18 via Frontend Transport; Fri, 25 Jun 2021 23:48:07 +0000 X-MS-Exchange-Authentication-Results: spf=pass (sender IP is 216.228.112.35) smtp.mailfrom=nvidia.com; gmail.com; dkim=none (message not signed) header.d=none;gmail.com; dmarc=pass action=none header.from=nvidia.com; Received-SPF: Pass (protection.outlook.com: domain of nvidia.com designates 216.228.112.35 as permitted sender) receiver=protection.outlook.com; client-ip=216.228.112.35; helo=mail.nvidia.com; Received: from mail.nvidia.com (216.228.112.35) by BN8NAM11FT024.mail.protection.outlook.com (10.13.177.38) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id 15.20.4264.18 via Frontend Transport; Fri, 25 Jun 2021 23:48:06 +0000 Received: from HQMAIL101.nvidia.com (172.20.187.10) by HQMAIL111.nvidia.com (172.20.187.18) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Fri, 25 Jun 2021 23:48:05 +0000 Received: from dipenp.nvidia.com (172.20.187.6) by mail.nvidia.com (172.20.187.10) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Fri, 25 Jun 2021 23:48:05 +0000 From: Dipen Patel To: , , , , , , , , , , , Subject: [RFC 01/11] Documentation: Add HTE subsystem guide Date: Fri, 25 Jun 2021 16:55:22 -0700 Message-ID: <20210625235532.19575-2-dipenp@nvidia.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20210625235532.19575-1-dipenp@nvidia.com> References: <20210625235532.19575-1-dipenp@nvidia.com> X-NVConfidentiality: public MIME-Version: 1.0 Content-Type: text/plain X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 158268eb-c5fe-46ad-cbb3-08d93833ae43 X-MS-TrafficTypeDiagnostic: BN8PR12MB3124: X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:8882; X-MS-Exchange-SenderADCheck: 1 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:216.228.112.35;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:schybrid02.nvidia.com;CAT:NONE;SFS:(4636009)(39860400002)(346002)(136003)(396003)(376002)(46966006)(36840700001)(7416002)(2616005)(70586007)(70206006)(8676002)(86362001)(2906002)(7696005)(6666004)(8936002)(921005)(7636003)(356005)(26005)(83380400001)(336012)(478600001)(426003)(110136005)(186003)(36756003)(82310400003)(47076005)(36860700001)(1076003)(5660300002)(316002)(82740400003)(2101003)(83996005);DIR:OUT;SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 25 Jun 2021 23:48:06.6023 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 158268eb-c5fe-46ad-cbb3-08d93833ae43 X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.112.35];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: BN8NAM11FT024.eop-nam11.prod.protection.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: BN8PR12MB3124 Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org Adding hte document which can help understand various APIs implemented in HTE framework for the HTE producers and the consumers. Signed-off-by: Dipen Patel --- Documentation/hte/hte.rst | 198 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 198 insertions(+) create mode 100644 Documentation/hte/hte.rst diff --git a/Documentation/hte/hte.rst b/Documentation/hte/hte.rst new file mode 100644 index 000000000000..11744dbc6d16 --- /dev/null +++ b/Documentation/hte/hte.rst @@ -0,0 +1,198 @@ +============================================ +The Linux Hardware Timestamping Engine (HTE) +============================================ + +:Author: Dipen Patel + +Introduction +------------ + +The certain devices have the built in hardware timestamping engine which can +monitor sets of system signals, lines, buses etc... in realtime for the state +change; upon detecting the change it can automatically store the timestamp at +the moment of occurrence. Such functionality may help achieve better accuracy +in obtaining timestamp than using software counterparts i.e. ktime and friends. + +This document describes the API that can be used by hardware timestamping +engine provider and consumer drivers that want to use the hardware timestamping +engine (HTE) framework. + +The HTE framework APIs for the providers +---------------------------------------- +Each driver must #include . The ``linux/hte.h`` declares the +following functions for the provider: + +.. c:function:: int hte_register_chip( struct hte_chip *chip ) + int hte_unregister_chip( struct hte_chip *chip ) + + The provider uses these APIs to un/register itself with HTE framework. + +.. c:function:: int hte_push_ts_ns_atomic( const struct hte_chip *chip, u32 xlated_id, struct hte_ts_data *data, size_t n ) + + The provider pushes timestamp data in nano seconds unit using this API. + +The detail about parameters and API usage are described in each functions +definitions in ``drivers/hte/hte.c`` file. + +The HTE framework APIs for the consumers +---------------------------------------- +The consumers use following APIs to control the line for the timestamp: + +.. c:function:: int hte_release_ts( struct hte_ts_desc *desc ) + int devm_hte_release_ts( struct device *dev, struct hte_ts_desc *desc ) + + The consumer uses API to release specified desc from timestamping. + The API frees resources associated with the desc and disables the + timestamping on it. The later is managed version of the same API. + +.. c:function:: struct hte_ts_desc *of_hte_request_ts( struct device *dev, const char *label, void (*cb)(enum hte_notify n) ) + struct hte_ts_desc *devm_of_hte_request_ts( struct device *dev, const char *label, void (*cb)(enum hte_notify n) ) + + The consumers can use above request APIs to request real timestamp + capability on specified entity. The later is resource managed version + of the of_hte_request_ts API. Both the APIs expect consumer to follow + device tree bindings for the HTE consumer. The details about binding + is in ``Documentation/devicetree/bindings/hte/hte-consumer.yaml``. + +.. c:function:: struct hte_ts_desc *hte_req_ts_by_dt_node( struct device_node *of_node, unsigned int id, void (*cb)(enum hte_notify n) ) + + The consumer can request timestamping directly specifying provider + device tree node. + +.. c:function:: int hte_enable_ts( struct hte_ts_desc *desc ) +.. c:function:: int hte_disable_ts( struct hte_ts_desc *desc ) + + The consumer can enable/disable timestamping on given desc. + +.. c:function:: int hte_retrieve_ts_ns( const struct hte_ts_desc *desc, struct hte_ts_data *el, size_t n ) + int hte_retrieve_ts_ns_wait( const struct hte_ts_desc *desc, struct hte_ts_data *el, size_t n ) + + The consumer uses above two API versions to get/retrieve timestamp data + for the given desc. The later is blocking version. + +.. c:function:: hte_get_clk_src_info(const struct hte_line_desc *desc, struct hte_clk_info *ci) + + The consumer retrieves clock source information that provider uses to + timestamp entity in the structure hte_clk_info. This information + specifies clock rate in HZ and clock. + +The details on struct hte_clk_info +----------------------------------- +This structure presents detail of the hardware clock that provider uses for +realtime timestamping purposes. The consumer can use hte_get_clk_src_info API +to get the information in hte_clk_info structure. It has hz and type parameters +where hz represents clock rate in HZ and type is clock type of clockid_t and +of CLOCK_* family (for example, CLOCK_MONOTONIC). + +The consumers calling of_hte_request_ts or hte_req_ts_by_dt_node APIs with +cb parameter set, usually will call hte_retrieve_ts (non blocking +version) after being notified by the callbacks from HTE subsystem. The +consumers calling those requests APIs with cb parameter NULL, usually will call +hte_retrieve_ts_wait API. + +The HTE subsystem provides software buffer per requested id/entity to store +timestamp data (struct hte_ts_data type). The consumers can manage the buffer. +It also provides buffer watermark which can notify (if cb parameter is provided +during request API call) consumer or unblock consumers calling +hte_retrieve_ts_wait API. The following APIs are used to manipulate the +software buffer: + +.. c:function:: int hte_set_buf_len( const struct hte_ts_desc *desc,unsigned int len ) + int hte_get_buf_len( const struct hte_ts_desc *desc ) + + The consumer uses above APIs to set/get software buffer depth. + +.. c:function:: int hte_set_buf_watermark( const struct hte_ts_desc *desc, unsigned int val ) + int hte_get_buf_watermark( const struct hte_ts_desc *desc ) + + The consumer uses above APIs to set/get software threshold, threshold + can be used to notity or unblock waiting consumer when data becomes + available equal or above to threshold value. + +.. c:function:: size_t hte_available_ts( const struct hte_ts_desc *desc ) + + The consumer uses above API to get available timestamp data stored + in the software buffer for the desc. + +The detail about parameters and API usage are described in each functions +definitions in ``drivers/hte/hte.c`` file. + +The HTE timestamp element detail +-------------------------------- +The struct hte_ts_data, declared at ``include/linux/hte.h``, is used to pass +timestamp details between the consumers and the providers. It expresses +timestamp data in nano second in u64 data type. For now all the HTE APIs +using struct hte_ts_data requires tsc to be in nano seconds. The timestamp +element structure stores below information along with timestamp data:: + + struct hte_ts_data { + /* + * Timestamp value + */ + u64 tsc; + /* + * The sequence counter, keep track of the number of timestamps. + * It can be used to check if data is dropped in between. + */ + u64 seq; + /* Direction of the event, i.e. falling or rising */ + int dir; + }; + +The typical hte_ts_data data life cycle:: +In this example the provider provides timestamp in nano seconds and for the +GPIO line:: + + - Monitors GPIO line change. + - Detects the state change on GPIO line. + - Converts timestamps in nano seconds and stores it in tsc. + - Stores GPIO direction in dir variable if the provider has that hardware + capability. + - Pushes this hte_timestamp_el object to HTE subsystem. + - HTE subsystem increments seq counter and stores it in software buffer + dedicated to requested GPIO line. + - Waiting consumer gets notified. + - The consumer calls the retrieve timestamp API. + +HTE subsystem debugfs attributes +-------------------------------- +HTE subsystem creates debugfs attributes at ``/sys/kernel/debug/hte/``. +It also creates line/signal related debugfs attributes at +``/sys/kernel/debug/hte//