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Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/devicetree/bindings/timestamp/hardware-timestamps-common.yaml | 29 | ||||
| -rw-r--r-- | Documentation/devicetree/bindings/timestamp/hte-consumer.yaml | 39 | ||||
| -rw-r--r-- | Documentation/devicetree/bindings/timestamp/nvidia,tegra194-hte.yaml | 88 | ||||
| -rw-r--r-- | Documentation/hte/hte.rst | 79 | ||||
| -rw-r--r-- | Documentation/hte/index.rst | 22 | ||||
| -rw-r--r-- | Documentation/hte/tegra194-hte.rst | 49 | ||||
| -rw-r--r-- | Documentation/index.rst | 1 |
7 files changed, 307 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/timestamp/hardware-timestamps-common.yaml b/Documentation/devicetree/bindings/timestamp/hardware-timestamps-common.yaml new file mode 100644 index 000000000000..fd6a7b51f571 --- /dev/null +++ b/Documentation/devicetree/bindings/timestamp/hardware-timestamps-common.yaml @@ -0,0 +1,29 @@ +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/timestamp/hardware-timestamps-common.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: Hardware timestamp providers + +maintainers: + - Dipen Patel <dipenp@nvidia.com> + +description: + Some devices/SoCs have hardware timestamp engines (HTE) which can use + hardware means to timestamp entity in realtime. The entity could be anything + from GPIOs, IRQs, Bus and so on. The hardware timestamp engine present + itself as a provider with the bindings described in this document. + +properties: + $nodename: + pattern: "^timestamp(@.*|-[0-9a-f])?$" + + "#timestamp-cells": + description: + Number of cells in a HTE specifier. + +required: + - "#timestamp-cells" + +additionalProperties: true diff --git a/Documentation/devicetree/bindings/timestamp/hte-consumer.yaml b/Documentation/devicetree/bindings/timestamp/hte-consumer.yaml new file mode 100644 index 000000000000..6456515c3d26 --- /dev/null +++ b/Documentation/devicetree/bindings/timestamp/hte-consumer.yaml @@ -0,0 +1,39 @@ +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/timestamp/hte-consumer.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: HTE Consumer Device Tree Bindings + +maintainers: + - Dipen Patel <dipenp@nvidia.com> + +select: true + +properties: + timestamps: + $ref: /schemas/types.yaml#/definitions/phandle-array + description: + The list of HTE provider phandle. The first cell must represent the + provider phandle followed by the line identifiers. The meaning of the + line identifier and exact number of arguments must be specified in the + HTE provider device tree binding document. + + timestamp-names: + $ref: /schemas/types.yaml#/definitions/string-array + description: + An optional string property to label each line specifier present in the + timestamp property. + +dependencies: + timestamp-names: [ timestamps ] + +additionalProperties: true + +examples: + - | + hte_tegra_consumer { + timestamps = <&tegra_hte_aon 0x9>, <&tegra_hte_lic 0x19>; + timestamp-names = "hte-gpio", "hte-i2c"; + }; diff --git a/Documentation/devicetree/bindings/timestamp/nvidia,tegra194-hte.yaml b/Documentation/devicetree/bindings/timestamp/nvidia,tegra194-hte.yaml new file mode 100644 index 000000000000..c31e207d1652 --- /dev/null +++ b/Documentation/devicetree/bindings/timestamp/nvidia,tegra194-hte.yaml @@ -0,0 +1,88 @@ +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/timestamp/nvidia,tegra194-hte.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: Tegra194 on chip generic hardware timestamping engine (HTE) + +maintainers: + - Dipen Patel <dipenp@nvidia.com> + +description: + Tegra SoC has two instances of generic hardware timestamping engines (GTE) + known as GTE GPIO and GTE IRQ, which can monitor subset of GPIO and on chip + IRQ lines for the state change respectively, upon detection it will record + timestamp (taken from system counter) in its internal hardware FIFO. It has + a bitmap array arranged in 32bit slices where each bit represent signal/line + to enable or disable for the hardware timestamping. The GTE GPIO monitors + GPIO lines from the AON (always on) GPIO controller. + +properties: + compatible: + enum: + - nvidia,tegra194-gte-aon + - nvidia,tegra194-gte-lic + + reg: + maxItems: 1 + + interrupts: + maxItems: 1 + + nvidia,int-threshold: + $ref: /schemas/types.yaml#/definitions/uint32 + description: + HTE device generates its interrupt based on this u32 FIFO threshold + value. The recommended value is 1. + minimum: 1 + maximum: 256 + + nvidia,slices: + $ref: /schemas/types.yaml#/definitions/uint32 + description: + HTE lines are arranged in 32 bit slice where each bit represents different + line/signal that it can enable/configure for the timestamp. It is u32 + property and depends on the HTE instance in the chip. The value 3 is for + GPIO GTE and 11 for IRQ GTE. + enum: [3, 11] + + '#timestamp-cells': + description: + This represents number of line id arguments as specified by the + consumers. For the GTE IRQ, this is IRQ number as mentioned in the + SoC technical reference manual. For the GTE GPIO, its value is same as + mentioned in the nvidia GPIO device tree binding document. + const: 1 + +required: + - compatible + - reg + - interrupts + - nvidia,slices + - "#timestamp-cells" + +additionalProperties: false + +examples: + - | + tegra_hte_aon: timestamp@c1e0000 { + compatible = "nvidia,tegra194-gte-aon"; + reg = <0xc1e0000 0x10000>; + interrupts = <0 13 0x4>; + nvidia,int-threshold = <1>; + nvidia,slices = <3>; + #timestamp-cells = <1>; + }; + + - | + tegra_hte_lic: timestamp@3aa0000 { + compatible = "nvidia,tegra194-gte-lic"; + reg = <0x3aa0000 0x10000>; + interrupts = <0 11 0x4>; + nvidia,int-threshold = <1>; + nvidia,slices = <11>; + #timestamp-cells = <1>; + }; + +... diff --git a/Documentation/hte/hte.rst b/Documentation/hte/hte.rst new file mode 100644 index 000000000000..153f3233c100 --- /dev/null +++ b/Documentation/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>/``. diff --git a/Documentation/hte/index.rst b/Documentation/hte/index.rst new file mode 100644 index 000000000000..9f43301c05dc --- /dev/null +++ b/Documentation/hte/index.rst @@ -0,0 +1,22 @@ +.. 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 + diff --git a/Documentation/hte/tegra194-hte.rst b/Documentation/hte/tegra194-hte.rst new file mode 100644 index 000000000000..41983e04d2a0 --- /dev/null +++ b/Documentation/hte/tegra194-hte.rst @@ -0,0 +1,49 @@ +.. 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. diff --git a/Documentation/index.rst b/Documentation/index.rst index 67036a05b771..8f9be0e658b4 100644 --- a/Documentation/index.rst +++ b/Documentation/index.rst @@ -137,6 +137,7 @@ needed). scheduler/index mhi/index peci/index + hte/index Architecture-agnostic documentation ----------------------------------- |