[V2,06/11] dts: bindings: Document device tree bindings for ETE

From: Suzuki K Poulose <suzuki.poulose@arm.com>

Document the device tree bindings for Embedded Trace Extensions.
ETE can be connected to legacy coresight components and thus
could optionally contain a connection graph as described by
the CoreSight bindings.

Cc: devicetree@vger.kernel.org
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Rob Herring <robh@kernel.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
---
 Documentation/devicetree/bindings/arm/ete.yaml | 71 ++++++++++++++++++++++++++
 1 file changed, 71 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/arm/ete.yaml

On Wed, Jan 13, 2021 at 09:48:13AM +0530, Anshuman Khandual wrote:
> From: Suzuki K Poulose <suzuki.poulose@arm.com>
> 
> Document the device tree bindings for Embedded Trace Extensions.
> ETE can be connected to legacy coresight components and thus
> could optionally contain a connection graph as described by
> the CoreSight bindings.
> 
> Cc: devicetree@vger.kernel.org
> Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
> Cc: Mike Leach <mike.leach@linaro.org>
> Cc: Rob Herring <robh@kernel.org>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
> ---
>  Documentation/devicetree/bindings/arm/ete.yaml | 71 ++++++++++++++++++++++++++
>  1 file changed, 71 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/arm/ete.yaml
> 
> diff --git a/Documentation/devicetree/bindings/arm/ete.yaml b/Documentation/devicetree/bindings/arm/ete.yaml
> new file mode 100644
> index 0000000..00e6a77
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/arm/ete.yaml
> @@ -0,0 +1,71 @@
> +# SPDX-License-Identifier: GPL-2.0-only or BSD-2-Clause
> +# Copyright 2021, Arm Ltd
> +%YAML 1.2
> +---
> +$id: "http://devicetree.org/schemas/arm/ete.yaml#"
> +$schema: "http://devicetree.org/meta-schemas/core.yaml#"
> +
> +title: ARM Embedded Trace Extensions
> +
> +maintainers:
> +  - Suzuki K Poulose <suzuki.poulose@arm.com>
> +  - Mathieu Poirier <mathieu.poirier@linaro.org>
> +
> +description: |
> +  Arm Embedded Trace Extension(ETE) is a per CPU trace component that
> +  allows tracing the CPU execution. It overlaps with the CoreSight ETMv4
> +  architecture and has extended support for future architecture changes.
> +  The trace generated by the ETE could be stored via legacy CoreSight
> +  components (e.g, TMC-ETR) or other means (e.g, using a per CPU buffer
> +  Arm Trace Buffer Extension (TRBE)). Since the ETE can be connected to
> +  legacy CoreSight components, a node must be listed per instance, along
> +  with any optional connection graph as per the coresight bindings.
> +  See bindings/arm/coresight.txt.
> +
> +properties:
> +  $nodename:
> +    pattern: "^ete([0-9a-f]+)$"
> +  compatible:
> +    items:
> +      - const: arm,embedded-trace-extension
> +
> +  cpu:

We use 'cpus' in a couple of other places, let's do that here for 
consistency.

> +    description: |
> +      Handle to the cpu this ETE is bound to.
> +    $ref: /schemas/types.yaml#/definitions/phandle
> +
> +  out-ports:
> +    description: |
> +      Out put connections from the ETE to legacy CoreSight trace bus.

Output

> +    $ref: /schemas/graph.yaml#/properties/ports

You have to define what each 'port' is if there can be more than 1. If 
there's only ever 1 then you just need 'port' though maybe all the 
coresight bindings require 'out-ports'. And the port nodes need a $ref 
to '/schemas/graph.yaml#/properties/port'.

> +
> +required:
> +  - compatible
> +  - cpu
> +
> +additionalProperties: false
> +
> +examples:
> +
> +# An ETE node without legacy CoreSight connections
> +  - |
> +    ete0 {
> +      compatible = "arm,embedded-trace-extension";
> +      cpu = <&cpu_0>;
> +    };
> +# An ETE node with legacy CoreSight connections
> +  - |
> +   ete1 {
> +      compatible = "arm,embedded-trace-extension";
> +      cpu = <&cpu_1>;
> +
> +      out-ports {        /* legacy coresight connection */
> +         port {
> +             ete1_out_port: endpoint {
> +                remote-endpoint = <&funnel_in_port0>;
> +             };
> +         };
> +      };
> +   };
> +
> +...
> -- 
> 2.7.4
>

Hi Rob

On 1/25/21 7:22 PM, Rob Herring wrote:
> On Wed, Jan 13, 2021 at 09:48:13AM +0530, Anshuman Khandual wrote:
>> From: Suzuki K Poulose <suzuki.poulose@arm.com>
>>
>> Document the device tree bindings for Embedded Trace Extensions.
>> ETE can be connected to legacy coresight components and thus
>> could optionally contain a connection graph as described by
>> the CoreSight bindings.
>>
>> Cc: devicetree@vger.kernel.org
>> Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
>> Cc: Mike Leach <mike.leach@linaro.org>
>> Cc: Rob Herring <robh@kernel.org>
>> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
>> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
>> ---
>>   Documentation/devicetree/bindings/arm/ete.yaml | 71 ++++++++++++++++++++++++++
>>   1 file changed, 71 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/arm/ete.yaml
>>
>> diff --git a/Documentation/devicetree/bindings/arm/ete.yaml b/Documentation/devicetree/bindings/arm/ete.yaml
>> new file mode 100644
>> index 0000000..00e6a77
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/arm/ete.yaml
>> @@ -0,0 +1,71 @@
>> +# SPDX-License-Identifier: GPL-2.0-only or BSD-2-Clause
>> +# Copyright 2021, Arm Ltd
>> +%YAML 1.2
>> +---
>> +$id: "http://devicetree.org/schemas/arm/ete.yaml#"
>> +$schema: "http://devicetree.org/meta-schemas/core.yaml#"
>> +
>> +title: ARM Embedded Trace Extensions
>> +
>> +maintainers:
>> +  - Suzuki K Poulose <suzuki.poulose@arm.com>
>> +  - Mathieu Poirier <mathieu.poirier@linaro.org>
>> +
>> +description: |
>> +  Arm Embedded Trace Extension(ETE) is a per CPU trace component that
>> +  allows tracing the CPU execution. It overlaps with the CoreSight ETMv4
>> +  architecture and has extended support for future architecture changes.
>> +  The trace generated by the ETE could be stored via legacy CoreSight
>> +  components (e.g, TMC-ETR) or other means (e.g, using a per CPU buffer
>> +  Arm Trace Buffer Extension (TRBE)). Since the ETE can be connected to
>> +  legacy CoreSight components, a node must be listed per instance, along
>> +  with any optional connection graph as per the coresight bindings.
>> +  See bindings/arm/coresight.txt.
>> +
>> +properties:
>> +  $nodename:
>> +    pattern: "^ete([0-9a-f]+)$"
>> +  compatible:
>> +    items:
>> +      - const: arm,embedded-trace-extension
>> +
>> +  cpu:
> 
> We use 'cpus' in a couple of other places, let's do that here for
> consistency.

This is following the existing CoreSight bindings for ETM. The same driver
probes both. Also there can only ever be a single CPU for ete/etm. So, we
would prefer to keep it aligned with the existing bindings to avoid causing
confusion.

> 
>> +    description: |
>> +      Handle to the cpu this ETE is bound to.
>> +    $ref: /schemas/types.yaml#/definitions/phandle
>> +
>> +  out-ports:
>> +    description: |
>> +      Out put connections from the ETE to legacy CoreSight trace bus.
> 
> Output

Will fix.

> 
>> +    $ref: /schemas/graph.yaml#/properties/ports
> 
> You have to define what each 'port' is if there can be more than 1. If
> there's only ever 1 then you just need 'port' though maybe all the
> coresight bindings require 'out-ports'. And the port nodes need a $ref
> to '/schemas/graph.yaml#/properties/port'.

All CoreSight components require an out-ports and/or in-ports. The ETM/ETE
always has one port, but must be under out-ports in line with the CoreSight
bindings.

Does this look more apt:

    out-ports:
      description: |
        Output connection from the ETE to legacy CoreSight trace bus.
      poperties:
         port:
           $ref: /schemas/graph.yaml#/properties/port

Suzuki

On 1/25/21 10:20 PM, Suzuki K Poulose wrote:
> Hi Rob
> 
> On 1/25/21 7:22 PM, Rob Herring wrote:
>> On Wed, Jan 13, 2021 at 09:48:13AM +0530, Anshuman Khandual wrote:
>>> From: Suzuki K Poulose <suzuki.poulose@arm.com>
>>>
>>> Document the device tree bindings for Embedded Trace Extensions.
>>> ETE can be connected to legacy coresight components and thus
>>> could optionally contain a connection graph as described by
>>> the CoreSight bindings.
>>>
>>> Cc: devicetree@vger.kernel.org
>>> Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
>>> Cc: Mike Leach <mike.leach@linaro.org>
>>> Cc: Rob Herring <robh@kernel.org>
>>> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
>>> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
>>> ---
>>>   Documentation/devicetree/bindings/arm/ete.yaml | 71 ++++++++++++++++++++++++++
>>>   1 file changed, 71 insertions(+)
>>>   create mode 100644 Documentation/devicetree/bindings/arm/ete.yaml
>>>
>>> diff --git a/Documentation/devicetree/bindings/arm/ete.yaml 
>>> b/Documentation/devicetree/bindings/arm/ete.yaml
>>> new file mode 100644
>>> index 0000000..00e6a77
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/arm/ete.yaml
>>> @@ -0,0 +1,71 @@
>>> +# SPDX-License-Identifier: GPL-2.0-only or BSD-2-Clause
>>> +# Copyright 2021, Arm Ltd
>>> +%YAML 1.2
>>> +---
>>> +$id: "http://devicetree.org/schemas/arm/ete.yaml#"
>>> +$schema: "http://devicetree.org/meta-schemas/core.yaml#"
>>> +
>>> +title: ARM Embedded Trace Extensions
>>> +
>>> +maintainers:
>>> +  - Suzuki K Poulose <suzuki.poulose@arm.com>
>>> +  - Mathieu Poirier <mathieu.poirier@linaro.org>
>>> +
>>> +description: |
>>> +  Arm Embedded Trace Extension(ETE) is a per CPU trace component that
>>> +  allows tracing the CPU execution. It overlaps with the CoreSight ETMv4
>>> +  architecture and has extended support for future architecture changes.
>>> +  The trace generated by the ETE could be stored via legacy CoreSight
>>> +  components (e.g, TMC-ETR) or other means (e.g, using a per CPU buffer
>>> +  Arm Trace Buffer Extension (TRBE)). Since the ETE can be connected to
>>> +  legacy CoreSight components, a node must be listed per instance, along
>>> +  with any optional connection graph as per the coresight bindings.
>>> +  See bindings/arm/coresight.txt.
>>> +
>>> +properties:
>>> +  $nodename:
>>> +    pattern: "^ete([0-9a-f]+)$"
>>> +  compatible:
>>> +    items:
>>> +      - const: arm,embedded-trace-extension
>>> +
>>> +  cpu:
>>
>> We use 'cpus' in a couple of other places, let's do that here for
>> consistency.
> 
> This is following the existing CoreSight bindings for ETM. The same driver
> probes both. Also there can only ever be a single CPU for ete/etm. So, we
> would prefer to keep it aligned with the existing bindings to avoid causing
> confusion.
> 
>>
>>> +    description: |
>>> +      Handle to the cpu this ETE is bound to.
>>> +    $ref: /schemas/types.yaml#/definitions/phandle
>>> +
>>> +  out-ports:
>>> +    description: |
>>> +      Out put connections from the ETE to legacy CoreSight trace bus.
>>
>> Output
> 
> Will fix.
> 
>>
>>> +    $ref: /schemas/graph.yaml#/properties/ports
>>
>> You have to define what each 'port' is if there can be more than 1. If
>> there's only ever 1 then you just need 'port' though maybe all the
>> coresight bindings require 'out-ports'. And the port nodes need a $ref
>> to '/schemas/graph.yaml#/properties/port'.
> 
> All CoreSight components require an out-ports and/or in-ports. The ETM/ETE
> always has one port, but must be under out-ports in line with the CoreSight
> bindings.
> 
> Does this look more apt:
> 
>     out-ports:
>       description: |
>         Output connection from the ETE to legacy CoreSight trace bus.
>       poperties:
>          port:
>            $ref: /schemas/graph.yaml#/properties/port


Correction, the above should be :

+  out-ports:
+    type: object
+    description: |
+      Output connections from the ETE to legacy CoreSight trace bus.
+    properties:
+      port:
+        $ref: /schemas/graph.yaml#/properties/port


That works fine for me. Does that look fine ?  Some day, we should convert the
coresight dt bindings to yaml and import the out-ports/in-ports from the scheme :-)

Cheers
Suzuki