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diff --git a/Documentation/driver-api/hte/tegra194-hte.rst b/Documentation/driver-api/hte/tegra194-hte.rst deleted file mode 100644 index f2d617265546..000000000000 --- a/Documentation/driver-api/hte/tegra194-hte.rst +++ /dev/null @@ -1,48 +0,0 @@ -.. 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. - -See gpiod_enable_hw_timestamp_ns() and 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/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 -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. |