--- /dev/null
+.. SPDX-License-Identifier: GPL-2.0+
+
+============================================
+The Linux Hardware Timestamping Engine (HTE)
+============================================
+
+:Author: Dipen Patel
+
+Introduction
+------------
+
+Certain devices have built in hardware timestamping engines which can
+monitor sets of system signals, lines, buses etc... in realtime for state
+change; upon detecting the change they can automatically store the timestamp at
+the moment of occurrence. Such functionality may help achieve better accuracy
+in obtaining timestamps 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. Both consumers and providers must include
+``#include <linux/hte.h>``.
+
+The HTE framework APIs for the providers
+----------------------------------------
+
+.. kernel-doc:: drivers/hte/hte.c
+ :functions: devm_hte_register_chip hte_push_ts_ns
+
+The HTE framework APIs for the consumers
+----------------------------------------
+
+.. kernel-doc:: drivers/hte/hte.c
+ :functions: hte_init_line_attr hte_ts_get hte_ts_put devm_hte_request_ts_ns hte_request_ts_ns hte_enable_ts hte_disable_ts of_hte_req_count hte_get_clk_src_info
+
+The HTE framework public structures
+-----------------------------------
+.. kernel-doc:: include/linux/hte.h
+
+More on the HTE timestamp data
+------------------------------
+The ``struct hte_ts_data`` is used to pass timestamp details between the
+consumers and the providers. It expresses timestamp data in nanoseconds in
+u64. An example of the typical timestamp data life cycle, for the GPIO line is
+as follows::
+
+ - Monitors GPIO line change.
+ - Detects the state change on GPIO line.
+ - Converts timestamps in nanoseconds.
+ - Stores GPIO raw level in raw_level variable if the provider has that
+ hardware capability.
+ - Pushes this hte_ts_data object to HTE subsystem.
+ - HTE subsystem increments seq counter and invokes consumer provided callback.
+ Based on callback return value, the HTE core invokes secondary callback in
+ the thread context.
+
+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/<provider>/<label or line id>/``. Note that these
+attributes are read-only.
+
+`ts_requested`
+ The total number of entities requested from the given provider,
+ where entity is specified by the provider and could represent
+ lines, GPIO, chip signals, buses etc...
+ The attribute will be available at
+ ``/sys/kernel/debug/hte/<provider>/``.
+
+`total_ts`
+ The total number of entities supported by the provider.
+ The attribute will be available at
+ ``/sys/kernel/debug/hte/<provider>/``.
+
+`dropped_timestamps`
+ The dropped timestamps for a given line.
+ The attribute will be available at
+ ``/sys/kernel/debug/hte/<provider>/<label or line id>/``.
--- /dev/null
+.. SPDX-License-Identifier: GPL-2.0
+
+============================================
+The Linux Hardware Timestamping Engine (HTE)
+============================================
+
+The HTE Subsystem
+=================
+
+.. toctree::
+ :maxdepth: 1
+
+ hte
+
+HTE Tegra Provider
+==================
+
+.. toctree::
+ :maxdepth: 1
+
+ tegra194-hte
+
--- /dev/null
+.. SPDX-License-Identifier: GPL-2.0+
+
+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.
+
+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.
+
+.. kernel-doc:: drivers/gpio/gpiolib.c
+ :functions: gpiod_enable_hw_timestamp_ns gpiod_disable_hw_timestamp_ns
+
+For userspace consumers, GPIO_V2_LINE_FLAG_EVENT_CLOCK_HTE flag must be
+specified during IOCTL calls. Refer to ``tools/gpio/gpio-event-mon.c``, which
+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/hte/``
+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
+this GTE instance in the HTE framework.
+
+The provider source code of both IRQ and GPIO GTE instances is located at
+``drivers/hte/hte-tegra194.c``. The test driver
+``drivers/hte/hte-tegra194-test.c`` demonstrates HTE API usage for both IRQ
+and GPIO GTE.
xilinx/index
xillybus
zorro
+ hte/index
.. only:: subproject and html
+++ /dev/null
-.. SPDX-License-Identifier: GPL-2.0+
-
-============================================
-The Linux Hardware Timestamping Engine (HTE)
-============================================
-
-:Author: Dipen Patel
-
-Introduction
-------------
-
-Certain devices have built in hardware timestamping engines which can
-monitor sets of system signals, lines, buses etc... in realtime for state
-change; upon detecting the change they can automatically store the timestamp at
-the moment of occurrence. Such functionality may help achieve better accuracy
-in obtaining timestamps 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. Both consumers and providers must include
-``#include <linux/hte.h>``.
-
-The HTE framework APIs for the providers
-----------------------------------------
-
-.. kernel-doc:: drivers/hte/hte.c
- :functions: devm_hte_register_chip hte_push_ts_ns
-
-The HTE framework APIs for the consumers
-----------------------------------------
-
-.. kernel-doc:: drivers/hte/hte.c
- :functions: hte_init_line_attr hte_ts_get hte_ts_put devm_hte_request_ts_ns hte_request_ts_ns hte_enable_ts hte_disable_ts of_hte_req_count hte_get_clk_src_info
-
-The HTE framework public structures
------------------------------------
-.. kernel-doc:: include/linux/hte.h
-
-More on the HTE timestamp data
-------------------------------
-The ``struct hte_ts_data`` is used to pass timestamp details between the
-consumers and the providers. It expresses timestamp data in nanoseconds in
-u64. An example of the typical timestamp data life cycle, for the GPIO line is
-as follows::
-
- - Monitors GPIO line change.
- - Detects the state change on GPIO line.
- - Converts timestamps in nanoseconds.
- - Stores GPIO raw level in raw_level variable if the provider has that
- hardware capability.
- - Pushes this hte_ts_data object to HTE subsystem.
- - HTE subsystem increments seq counter and invokes consumer provided callback.
- Based on callback return value, the HTE core invokes secondary callback in
- the thread context.
-
-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/<provider>/<label or line id>/``. Note that these
-attributes are read-only.
-
-`ts_requested`
- The total number of entities requested from the given provider,
- where entity is specified by the provider and could represent
- lines, GPIO, chip signals, buses etc...
- The attribute will be available at
- ``/sys/kernel/debug/hte/<provider>/``.
-
-`total_ts`
- The total number of entities supported by the provider.
- The attribute will be available at
- ``/sys/kernel/debug/hte/<provider>/``.
-
-`dropped_timestamps`
- The dropped timestamps for a given line.
- The attribute will be available at
- ``/sys/kernel/debug/hte/<provider>/<label or line id>/``.
+++ /dev/null
-.. SPDX-License-Identifier: GPL-2.0
-
-============================================
-The Linux Hardware Timestamping Engine (HTE)
-============================================
-
-The HTE Subsystem
-=================
-
-.. toctree::
- :maxdepth: 1
-
- hte
-
-HTE Tegra Provider
-==================
-
-.. toctree::
- :maxdepth: 1
-
- tegra194-hte
-
+++ /dev/null
-.. SPDX-License-Identifier: GPL-2.0+
-
-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.
-
-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.
-
-.. kernel-doc:: drivers/gpio/gpiolib.c
- :functions: gpiod_enable_hw_timestamp_ns gpiod_disable_hw_timestamp_ns
-
-For userspace consumers, GPIO_V2_LINE_FLAG_EVENT_CLOCK_HTE flag must be
-specified during IOCTL calls. Refer to ``tools/gpio/gpio-event-mon.c``, which
-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/hte/``
-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
-this GTE instance in the HTE framework.
-
-The provider source code of both IRQ and GPIO GTE instances is located at
-``drivers/hte/hte-tegra194.c``. The test driver
-``drivers/hte/hte-tegra194-test.c`` demonstrates HTE API usage for both IRQ
-and GPIO GTE.
scheduler/index
mhi/index
peci/index
- hte/index
Architecture-agnostic documentation
-----------------------------------
M: Dipen Patel <dipenp@nvidia.com>
S: Maintained
F: Documentation/devicetree/bindings/timestamp/
-F: Documentation/hte/
+F: Documentation/driver-api/hte/
F: drivers/hte/
F: include/linux/hte.h
projects / kernel.git / commitdiff