Re: [PATCH v11 1/7] dt-bindings: arm: Add support for Qualcomm TGU trace

["Songwei.Chai" <songwei.chai@oss.qualcomm.com>]

On 2/26/2026 2:07 PM, Jie Gan wrote:
>
>
> On 2/26/2026 10:04 AM, Songwei Chai 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    |
>>   |                         |                     | |             |
>>   |-------------------------|                     | |-------------|
>>   |                         |                     |     | priority[3] |
>>   |         step[7]         |<--                  | |-------------|
>>   |-------------------------|   |                 |     | priority[2] |
>>   |                         |   |                 | |-------------|
>>   |           ...           |   |Steps region     |     | priority[1] |
>>   |                         |   |                 | |-------------|
>>   |-------------------------|   |                 |     | priority[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 tgu.yaml file to describe the bindings required to
>> define the TGU in the device trees.
>>
>> Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
>> Signed-off-by: Songwei Chai <songwei.chai@oss.qualcomm.com>
>> ---
>>   .../devicetree/bindings/arm/qcom,tgu.yaml     | 92 +++++++++++++++++++
>>   1 file changed, 92 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/arm/qcom,tgu.yaml
>>
>> diff --git a/Documentation/devicetree/bindings/arm/qcom,tgu.yaml 
>> b/Documentation/devicetree/bindings/arm/qcom,tgu.yaml
>> new file mode 100644
>> index 000000000000..5b6a58ebe691
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/arm/qcom,tgu.yaml
>> @@ -0,0 +1,92 @@
>> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
>> +# Copyright (c) 2025 Qualcomm Innovation Center, Inc. All rights 
>> reserved.
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/arm/qcom,tgu.yaml#
>> +$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 to identify the issue in time
>> +  once there is abnormal behavior in the subsystem.
>> +
>> +maintainers:
>> +  - Mao Jinlong <jinlong.mao@oss.qualcomm.com>
>> +  - Songwei Chai <songwei.chai@oss.qualcomm.com>
>> +
>> +# Need a custom select here or 'arm,primecell' will match on lots of 
>> nodes
>> +select:
>> +  properties:
>> +    compatible:
>> +      contains:
>> +        enum:
>> +          - qcom,tgu
>> +  required:
>> +    - compatible
>> +
>> +properties:
>> +  compatible:
>> +    items:
>> +      - const: qcom,tgu
>> +      - const: arm,primecell
>> +
>> +  reg:
>> +    maxItems: 1
>> +
>> +  clocks:
>> +    maxItems: 1
>> +
>> +  clock-names:
>> +    items:
>> +      - const: apb_pclk
>> +
>> +  in-ports:
>> +    $ref: /schemas/graph.yaml#/properties/ports
>> +    additionalProperties: false
>> +
>
> The TGU device is no longer a CoreSight device, so I think the 
> in-ports property is no longer needed.
>
> Thanks,
> Jie
>
Thanks Jie,

Your comment has been addressed and updated in V12.

>> +    properties:
>> +      port:
>> +        description:
>> +          The port mechanism here ensures the relationship between 
>> TGU and
>> +          TPDM, as TPDM is one of the inputs for TGU. It will allow 
>> TGU to
>> +          function as TPDM's helper and enable TGU when the connected
>> +          TPDM is enabled.
>> +        $ref: /schemas/graph.yaml#/properties/port
>> +
>> +required:
>> +  - compatible
>> +  - reg
>> +  - clocks
>> +  - clock-names
>> +
>> +additionalProperties: false
>> +
>> +examples:
>> +  - |
>> +    tgu@10b0e000 {
>> +        compatible = "qcom,tgu", "arm,primecell";
>> +        reg = <0x10b0e000 0x1000>;
>> +
>> +        clocks = <&aoss_qmp>;
>> +        clock-names = "apb_pclk";
>> +
>> +        in-ports {
>> +            port {
>> +                tgu_in_tpdm_swao: endpoint{
>> +                    remote-endpoint = <&tpdm_swao_out_tgu>;
>> +                };
>> +            };
>> +        };
>> +    };
>> +...
>