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| author | Rob Herring (Arm) <robh@kernel.org> | 2026-08-31 14:43:51 -0500 |
|---|---|---|
| committer | Dmitry Torokhov <dmitry.torokhov@gmail.com> | 2026-09-13 18:17:31 -0700 |
| commit | 55fc280e951ab2b39f3dcb640edc1b1eebc6d173 (patch) | |
| tree | f0b5f37b42fc13b9908a31b657c646b024231cdd /Documentation/driver-api/hte/hte.rst | |
| download | linux-stable-55fc280e951ab2b39f3dcb640edc1b1eebc6d173.tar.gz linux-stable-55fc280e951ab2b39f3dcb640edc1b1eebc6d173.zip | |
Input: tsc2007 - read "ti,poll-period" as u32grafted
The "ti,poll-period" property is documented as a normal uint32 cell.
The driver used a u64 helper, which makes the helper type disagree with
the schema even though the stored value is still small.
Read "ti,poll-period" with the u32 helper matching the documented DT
cell size.
Assisted-by: Codex:gpt-5-5
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://patch.msgid.link/20260831194352.1185860-1-robh@kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Diffstat (limited to 'Documentation/driver-api/hte/hte.rst')
| -rw-r--r-- | Documentation/driver-api/hte/hte.rst | 79 |
1 files changed, 79 insertions, 0 deletions
diff --git a/Documentation/driver-api/hte/hte.rst b/Documentation/driver-api/hte/hte.rst new file mode 100644 index 000000000..153f3233c --- /dev/null +++ b/Documentation/driver-api/hte/hte.rst @@ -0,0 +1,79 @@ +.. 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>/``. |
