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Tue, 14 Feb 2023 03:56:01 -0800 From: Dipen Patel To: , , , , , , , , , CC: Dipen Patel Subject: [PATCH V2 5/6] hte: Re-phrase tegra API document Date: Tue, 14 Feb 2023 03:55:52 -0800 Message-ID: <20230214115553.10416-6-dipenp@nvidia.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20230214115553.10416-1-dipenp@nvidia.com> References: <20230214115553.10416-1-dipenp@nvidia.com> X-NVConfidentiality: public Precedence: bulk X-Mailing-List: timestamp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DM6NAM11FT105:EE_|DM4PR12MB5168:EE_ X-MS-Office365-Filtering-Correlation-Id: 14095c0c-91a8-475c-42fe-08db0e827795 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:216.228.117.160;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:dc6edge1.nvidia.com;CAT:NONE;SFS:(13230025)(4636009)(376002)(136003)(346002)(396003)(39860400002)(451199018)(40470700004)(36840700001)(46966006)(26005)(186003)(2616005)(478600001)(41300700001)(40480700001)(107886003)(6666004)(336012)(7696005)(1076003)(110136005)(316002)(83380400001)(4326008)(356005)(8676002)(40460700003)(70206006)(921005)(8936002)(70586007)(7636003)(36756003)(426003)(47076005)(82740400003)(86362001)(5660300002)(2906002)(36860700001)(82310400005)(83996005)(2101003);DIR:OUT;SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 14 Feb 2023 11:56:11.6459 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 14095c0c-91a8-475c-42fe-08db0e827795 X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.117.160];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: DM6NAM11FT105.eop-nam11.prod.protection.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM4PR12MB5168 Make Tegra194 API document generic to make it applicable for current and future tegra hte providers. Signed-off-by: Dipen Patel --- Documentation/driver-api/hte/tegra194-hte.rst | 33 +++++++++---------- 1 file changed, 16 insertions(+), 17 deletions(-) diff --git a/Documentation/driver-api/hte/tegra194-hte.rst b/Documentation/driver-api/hte/tegra194-hte.rst index f2d617265546..85e654772782 100644 --- a/Documentation/driver-api/hte/tegra194-hte.rst +++ b/Documentation/driver-api/hte/tegra194-hte.rst @@ -5,25 +5,25 @@ HTE Kernel provider driver Description ----------- -The Nvidia tegra194 HTE provider driver implements two GTE -(Generic Timestamping Engine) instances: 1) GPIO GTE and 2) LIC -(Legacy Interrupt Controller) IRQ GTE. Both GTE instances get the -timestamp from the system counter TSC which has 31.25MHz clock rate, and the -driver converts clock tick rate to nanoseconds before storing it as timestamp -value. +The Nvidia tegra HTE provider also known as GTE (Generic Timestamping Engine) +driver implements two GTE instances: 1) GPIO GTE and 2) LIC +(Legacy Interrupt Controller) IRQ GTE. Both GTE instances get the timestamp +from the system counter TSC which has 31.25MHz clock rate, and the driver +converts clock tick rate to nanoseconds before storing it as timestamp value. GPIO GTE -------- This GTE instance timestamps GPIO in real time. For that to happen GPIO -needs to be configured as input. The always on (AON) GPIO controller instance -supports timestamping GPIOs in real time and it has 39 GPIO lines. The GPIO GTE -and AON GPIO controller are tightly coupled as it requires very specific bits -to be set in GPIO config register before GPIO GTE can be used, for that GPIOLIB -adds two optional APIs as below. The GPIO GTE code supports both kernel -and userspace consumers. The kernel space consumers can directly talk to HTE -subsystem while userspace consumers timestamp requests go through GPIOLIB CDEV -framework to HTE subsystem. +needs to be configured as input. Only the always on (AON) GPIO controller +instance supports timestamping GPIOs in real time as it is tightly coupled with +the GPIO GTE. To support this, GPIOLIB adds two optional APIs as mentioned +below. The GPIO GTE code supports both kernel and userspace consumers. The +kernel space consumers can directly talk to HTE subsystem while userspace +consumers timestamp requests go through GPIOLIB CDEV framework to HTE +subsystem. The hte devicetree binding described at +``Documentation/devicetree/bindings/timestamp`` provides an example of how a +consumer can request an GPIO line. See gpiod_enable_hw_timestamp_ns() and gpiod_disable_hw_timestamp_ns(). @@ -34,9 +34,8 @@ returns the timestamp in nanoseconds. LIC (Legacy Interrupt Controller) IRQ GTE ----------------------------------------- -This GTE instance timestamps LIC IRQ lines in real time. There are 352 IRQ -lines which this instance can add timestamps to in real time. The hte -devicetree binding described at ``Documentation/devicetree/bindings/timestamp`` +This GTE instance timestamps LIC IRQ lines in real time. The hte devicetree +binding described at ``Documentation/devicetree/bindings/timestamp`` provides an example of how a consumer can request an IRQ line. Since it is a one-to-one mapping with IRQ GTE provider, consumers can simply specify the IRQ number that they are interested in. There is no userspace consumer support for