driver-api/hte/tegra-hte.rst

1 .. SPDX-License-Identifier: GPL-2.0+
3 HTE Kernel provider driver
7 -----------
8 The Nvidia tegra HTE provider also known as GTE (Generic Timestamping Engine)
9 driver implements two GTE instances: 1) GPIO GTE and 2) LIC
14 GPIO GTE
15 --------
17 This GTE instance timestamps GPIO in real time. For that to happen GPIO
18 needs to be configured as input. Only the always on (AON) GPIO controller
20 the GPIO GTE. To support this, GPIOLIB adds two optional APIs as mentioned
21 below. The GPIO GTE code supports both kernel and userspace consumers. The
22 kernel space consumers can directly talk to HTE subsystem while userspace
23 consumers timestamp requests go through GPIOLIB CDEV framework to HTE
24 subsystem. The hte devicetree binding described at
26 consumer can request an GPIO line.
31 specified during IOCTL calls. Refer to ``tools/gpio/gpio-event-mon.c``, which
35 -----------------------------------------
37 This GTE instance timestamps LIC IRQ lines in real time. The hte devicetree
40 one-to-one mapping with IRQ GTE provider, consumers can simply specify the IRQ
42 this GTE instance in the HTE framework.
44 The provider source code of both IRQ and GPIO GTE instances is located at
45 ``drivers/hte/hte-tegra194.c``. The test driver
46 ``drivers/hte/hte-tegra194-test.c`` demonstrates HTE API usage for both IRQ
47 and GPIO GTE.