Re: [PATCH v1 1/7] dt-bindings: arm: Add support for Coresight TGU trace

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On 9/2/2024 3:02 PM, Krzysztof Kozlowski wrote:
On 02/09/2024 05:14, songchai wrote:
On 8/30/2024 6:11 PM, Krzysztof Kozlowski wrote:
On 30/08/2024 11:23, songchai wrote:
The Trigger Generation Unit (TGU) is designed to detect patterns or
sequences within a specific region of the System on Chip (SoC). Once
configured and activated, it monitors sense inputs and can detect a
pre-programmed state or sequence across clock cycles, subsequently
producing a trigger.

     TGU configuration space
          offset table
   x-------------------------x
   |                         |
   |                         |
   |                         |                           Step configuration
   |                         |                             space layout
   |   coresight management  |                           x-------------x
   |        registers        |                     |---> |             |
   |                         |                     |     |  reserve    |
   |                         |                     |     |             |
   |-------------------------|                     |     |-------------|
   |                         |                     |     | prioroty[3] |
   |         step[7]         |<--                  |     |-------------|
   |-------------------------|   |                 |     | prioroty[2] |
   |                         |   |                 |     |-------------|
   |           ...           |   |Steps region     |     | prioroty[1] |
   |                         |   |                 |     |-------------|
   |-------------------------|   |                 |     | prioroty[0] |
   |                         |<--                  |     |-------------|
   |         step[0]         |-------------------->      |             |
   |-------------------------|                           |  condition  |
   |                         |                           |             |
   |     control and status  |                           x-------------x
   |           space         |                           |             |
   x-------------------------x                           |Timer/Counter|
                                                         |             |
						       x-------------x
TGU Configuration in Hardware

The TGU provides a step region for user configuration, similar
to a flow chart. Each step region consists of three register clusters:

1.Priority Region: Sets the required signals with priority.
2.Condition Region: Defines specific requirements (e.g., signal A
reaches three times) and the subsequent action once the requirement is
met.
3.Timer/Counter (Optional): Provides timing or counting functionality.

Add a new coresight-tgu.yaml file to describe the bindings required to
define the TGU in the device trees.

Signed-off-by: songchai<quic_songchai@xxxxxxxxxxx>
It feels like you are using login name as real name. Please investigate
this and confirm whether latin transcription/transliteration of your
name is like above.
yes.. it's my login name. Will use my real name in next version.
---
   .../bindings/arm/qcom,coresight-tgu.yaml      | 136 ++++++++++++++++++
   1 file changed, 136 insertions(+)
   create mode 100644 Documentation/devicetree/bindings/arm/qcom,coresight-tgu.yaml

diff --git a/Documentation/devicetree/bindings/arm/qcom,coresight-tgu.yaml b/Documentation/devicetree/bindings/arm/qcom,coresight-tgu.yaml
new file mode 100644
index 000000000000..c261252e33e0
--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/qcom,coresight-tgu.yaml
@@ -0,0 +1,136 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+# Copyright (c) 2023 Qualcomm Innovation Center, Inc. All rights reserved.
+%YAML 1.2
+---
+$id:http://devicetree.org/schemas/arm/qcom,coresight-tgu.yaml#
+$schema:http://devicetree.org/meta-schemas/core.yaml#
+
+title: Trigger Generation Unit - TGU
+
+description: |
+  The Trigger Generation Unit (TGU) is a Data Engine which can be utilized
+  to sense a plurality of signals and create a trigger into the CTI or
+  generate interrupts to processors. The TGU is like the trigger circuit
+  of a Logic Analyzer.The corresponding trigger logic can be realized by
+  configuring the conditions for each step after sensing the signal.
+  Once setup and enabled, it will observe sense inputs and based upon
+  the activity of those inputs, even over clock cycles, may detect a
+  preprogrammed state/sequence and then produce a trigger or interrupt.
+
+  The primary use case of the TGU is to detect patterns or sequences on a
+  given set of signals within some region of the SoC.
+
+maintainers:
+  - Mao Jinlong<quic_jinlmao@xxxxxxxxxxx>
+  - Sam Chai<quic_songchai@xxxxxxxxxxx>
+
+# Need a custom select here or 'arm,primecell' will match on lots of nodes
+select:
+  properties:
+    compatible:
+      contains:
+        enum:
+          - qcom,coresight-tgu
+  required:
+    - compatible
+
+properties:
+  $nodename:
+    pattern: "^tgu(@[0-9a-f]+)$"
Drop the pattern (and anyway @ is not optional).
There will be several TGUs in the SoC, and we want to use the address of
each to distinguish them.
How is this related?

This is why we added the nodename pattern here.
How is this related?

Additionally, I noticed that both TPDM and CTI also use this format to
define the nodename.

Could you please share any concerns you have about using this pattern?
I don't get why you insist, but sure:
The name does not follow DT spec recommendation, plus child schema is
not really supposed to define the names.
Thanks for you clarification, will drop in the next version.

+  compatible:
+    items:
+      - const: qcom,coresight-tgu
+      - const: arm,primecell
+
+  reg:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+  clock-names:
+    items:
+      - const: apb_pclk
+
+  qcom,tgu-steps:
+    description:
+      The trigger logic is realized by configuring each step after sensing
+      the signal. The parameter here is used to describe the maximum of steps
+      that could be configured in the current TGU.
Why this is board or SoC level property? All below also feel like
unnecessary stuff from downstream.
There are actually four properties used to describe the number of
registers with different functionality for TGUs at the SoC level.

Each TGU may have a different number of registers, so we need to add
these four properties to describe each TGU’s hardware design.
Each TGU on the same SoC?
yes, in other words, there will be several TGUs in the SoC.



Best regards,
Krzysztof





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