[PATCH V3 06/14] dts: bindings: Document device tree bindings for ETE

[PATCH V3 06/14] dts: bindings: Document device tree bindings for ETE

[Anshuman Khandual]

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>
---
Changes in V3:

- Fixed all DT yaml semantics problems

 Documentation/devicetree/bindings/arm/ete.yaml | 74 ++++++++++++++++++++++++++
 1 file changed, 74 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..edc1fe2
--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/ete.yaml
@@ -0,0 +1,74 @@
+# 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:
+    description: |
+      Handle to the cpu this ETE is bound to.
+    $ref: /schemas/types.yaml#/definitions/phandle
+
+  out-ports:
+    type: object
+    description: |
+      Output connections from the ETE to legacy CoreSight trace bus.
+    properties:
+      port:
+        $ref: /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

Re: [PATCH V3 06/14] dts: bindings: Document device tree bindings for ETE

[Rob Herring]

On Wed, Jan 27, 2021 at 02:25:30PM +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>
> ---
> Changes in V3:
> 
> - Fixed all DT yaml semantics problems
> 
>  Documentation/devicetree/bindings/arm/ete.yaml | 74 ++++++++++++++++++++++++++
>  1 file changed, 74 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..edc1fe2
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/arm/ete.yaml
> @@ -0,0 +1,74 @@
> +# 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've already established 'cpus' for this purpose.

> +    description: |
> +      Handle to the cpu this ETE is bound to.
> +    $ref: /schemas/types.yaml#/definitions/phandle
> +
> +  out-ports:
> +    type: object

Replace with: $ref: /schemas/graph.yaml#/properties/ports

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

Actually, if only 1 port ever, you can drop 'out-ports' and just have 
'port'. Not sure though if the coresight stuff depends on 'out-ports'.

> +
> +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
> 

Re: [PATCH V3 06/14] dts: bindings: Document device tree bindings for ETE

[Suzuki K Poulose]

Hi Rob

On 2/9/21 7:00 PM, Rob Herring wrote:
> On Wed, Jan 27, 2021 at 02:25:30PM +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>
>> ---
>> Changes in V3:
>>
>> - Fixed all DT yaml semantics problems
>>
>>   Documentation/devicetree/bindings/arm/ete.yaml | 74 ++++++++++++++++++++++++++
>>   1 file changed, 74 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..edc1fe2
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/arm/ete.yaml
>> @@ -0,0 +1,74 @@
>> +# 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've already established 'cpus' for this purpose.
> 

Please see : https://lkml.kernel.org/r/9417218b-6eda-373b-a2cb-869089ffc7cd@arm.com
for my response in the previous version to this and the one with out-ports.

>> +    description: |
>> +      Handle to the cpu this ETE is bound to.
>> +    $ref: /schemas/types.yaml#/definitions/phandle
>> +
>> +  out-ports:
>> +    type: object
> 
> Replace with: $ref: /schemas/graph.yaml#/properties/ports

So, just to confirm again :
The CoreSight graph bindings expect the input ports and output ports
grouped under in-ports{} and out-ports{} respectively to avoid having
to specify the direction of the ports in the individual "port" nodes.
i.e

in-ports {

	property: ports
	  OR
	property: port

	required:
		OneOf:
			ports
			port
}

out-ports {

	# same as above
}

So thats why I added out-ports as a new object, where the ports/port
could be a child node.

Ideally the definition of out-ports /in-ports should go to a common schema
for CoreSight bindings, when we move to Yaml for the existing bindings,
which will follow in a separate series, later.

> 
>> +    description: |
>> +      Output connections from the ETE to legacy CoreSight trace bus.
>> +    properties:
>> +      port:
>> +        $ref: /schemas/graph.yaml#/properties/port
> 
> Actually, if only 1 port ever, you can drop 'out-ports' and just have
> 'port'. Not sure though if the coresight stuff depends on 'out-ports'.
> 

Cheers
Suzuki

Re: [PATCH V3 06/14] dts: bindings: Document device tree bindings for ETE

[Rob Herring]

On Wed, Feb 10, 2021 at 12:33:44PM +0000, Suzuki K Poulose wrote:
> Hi Rob
> 
> On 2/9/21 7:00 PM, Rob Herring wrote:
> > On Wed, Jan 27, 2021 at 02:25:30PM +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>
> > > ---
> > > Changes in V3:
> > > 
> > > - Fixed all DT yaml semantics problems
> > > 
> > >   Documentation/devicetree/bindings/arm/ete.yaml | 74 ++++++++++++++++++++++++++
> > >   1 file changed, 74 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..edc1fe2
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/arm/ete.yaml
> > > @@ -0,0 +1,74 @@
> > > +# 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've already established 'cpus' for this purpose.
> > 
> 
> Please see : https://lkml.kernel.org/r/9417218b-6eda-373b-a2cb-869089ffc7cd@arm.com
> for my response in the previous version to this and the one with out-ports.

Okay, fair enough.

> 
> > > +    description: |
> > > +      Handle to the cpu this ETE is bound to.
> > > +    $ref: /schemas/types.yaml#/definitions/phandle
> > > +
> > > +  out-ports:
> > > +    type: object
> > 
> > Replace with: $ref: /schemas/graph.yaml#/properties/ports
> 
> So, just to confirm again :
> The CoreSight graph bindings expect the input ports and output ports
> grouped under in-ports{} and out-ports{} respectively to avoid having
> to specify the direction of the ports in the individual "port" nodes.
> i.e
> 
> in-ports {
> 
> 	property: ports
> 	  OR
> 	property: port
> 
> 	required:
> 		OneOf:
> 			ports
> 			port

No, 'ports' as a child of in-ports is not correct. There should only be 
'port(@[0-9a-f]+)?' nodes. That's why you need the above $ref added. The 
$ref doesn't define the node name is 'ports', but what a 'ports' or 
'foo-ports' contains.

> }
> 
> out-ports {
> 
> 	# same as above
> }
> 
> So thats why I added out-ports as a new object, where the ports/port
> could be a child node.
> 
> Ideally the definition of out-ports /in-ports should go to a common schema
> for CoreSight bindings, when we move to Yaml for the existing bindings,
> which will follow in a separate series, later.

Yes, maybe, but I'm not sure something common is going to help here. 
You'll still have to describe what each 'port' node does in each device 
specific binding.

Rob

Re: [PATCH V3 06/14] dts: bindings: Document device tree bindings for ETE

[Suzuki K Poulose]

On 2/18/21 6:33 PM, Rob Herring wrote:
> On Wed, Feb 10, 2021 at 12:33:44PM +0000, Suzuki K Poulose wrote:
>> Hi Rob
>>
>> On 2/9/21 7:00 PM, Rob Herring wrote:
>>> On Wed, Jan 27, 2021 at 02:25:30PM +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>
>>>> ---
>>>> Changes in V3:
>>>>
>>>> - Fixed all DT yaml semantics problems
>>>>
>>>>    Documentation/devicetree/bindings/arm/ete.yaml | 74 ++++++++++++++++++++++++++
>>>>    1 file changed, 74 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..edc1fe2
>>>> --- /dev/null
>>>> +++ b/Documentation/devicetree/bindings/arm/ete.yaml
>>>> @@ -0,0 +1,74 @@
>>>> +# 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've already established 'cpus' for this purpose.
>>>
>>
>> Please see : https://lkml.kernel.org/r/9417218b-6eda-373b-a2cb-869089ffc7cd@arm.com
>> for my response in the previous version to this and the one with out-ports.
> 
> Okay, fair enough.
> 
>>
>>>> +    description: |
>>>> +      Handle to the cpu this ETE is bound to.
>>>> +    $ref: /schemas/types.yaml#/definitions/phandle
>>>> +
>>>> +  out-ports:
>>>> +    type: object
>>>
>>> Replace with: $ref: /schemas/graph.yaml#/properties/ports
>>
>> So, just to confirm again :
>> The CoreSight graph bindings expect the input ports and output ports
>> grouped under in-ports{} and out-ports{} respectively to avoid having
>> to specify the direction of the ports in the individual "port" nodes.
>> i.e
>>
>> in-ports {
>>
>> 	property: ports
>> 	  OR
>> 	property: port
>>
>> 	required:
>> 		OneOf:
>> 			ports
>> 			port
> 
> No, 'ports' as a child of in-ports is not correct. There should only be
> 'port(@[0-9a-f]+)?' nodes. That's why you need the above $ref added. The
> $ref doesn't define the node name is 'ports', but what a 'ports' or
> 'foo-ports' contains.

Sorry, it is my bad. We don't expect ports{} under in-ports. So your
suggestion is the accurate one. I will respin.



> 
>> }
>>
>> out-ports {
>>
>> 	# same as above
>> }
>>
>> So thats why I added out-ports as a new object, where the ports/port
>> could be a child node.
>>
>> Ideally the definition of out-ports /in-ports should go to a common schema
>> for CoreSight bindings, when we move to Yaml for the existing bindings,
>> which will follow in a separate series, later.
> 
> Yes, maybe, but I'm not sure something common is going to help here.
> You'll still have to describe what each 'port' node does in each device
> specific binding.

For CoreSight components the end-point of the ports are system specific.
i.e, it could be anything on the other end. There is no fixed end-point
connection.

e.g, ETM could be connected to a Replicator or a Funnel. Same as here
above for ETE. Thus the driver must parse the endpoints and make
the connection path from devices to other devices.

Anyways, will come to that in a different series.

I will fix the in-ports/out-ports for the next version.

Thanks for your guidance.

Cheers
Suzuki



> 
> Rob
> 

[PATCH V3 12/14] dts: bindings: Document device tree bindings for Arm TRBE

[Anshuman Khandual]

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

Document the device tree bindings for Trace Buffer Extension (TRBE).

Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Rob Herring <robh@kernel.org>
Cc: devicetree@vger.kernel.org
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
---
Changes in V3:

- Added missing description for the TRBE hardware
- Fixed all DT yaml semantics problems

 Documentation/devicetree/bindings/arm/trbe.yaml | 49 +++++++++++++++++++++++++
 1 file changed, 49 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/arm/trbe.yaml

diff --git a/Documentation/devicetree/bindings/arm/trbe.yaml b/Documentation/devicetree/bindings/arm/trbe.yaml
new file mode 100644
index 0000000..4402d7b
--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/trbe.yaml
@@ -0,0 +1,49 @@
+# SPDX-License-Identifier: GPL-2.0-only or BSD-2-Clause
+# Copyright 2021, Arm Ltd
+%YAML 1.2
+---
+$id: "http://devicetree.org/schemas/arm/trbe.yaml#"
+$schema: "http://devicetree.org/meta-schemas/core.yaml#"
+
+title: ARM Trace Buffer Extensions
+
+maintainers:
+  - Anshuman Khandual <anshuman.khandual@arm.com>
+
+description: |
+  Arm Trace Buffer Extension (TRBE) is a per CPU component
+  for storing trace generated on the CPU to memory. It is
+  accessed via CPU system registers. The software can verify
+  if it is permitted to use the component by checking the
+  TRBIDR register.
+
+properties:
+  $nodename:
+    const: "trbe"
+  compatible:
+    items:
+      - const: arm,trace-buffer-extension
+
+  interrupts:
+    description: |
+       Exactly 1 PPI must be listed. For heterogeneous systems where
+       TRBE is only supported on a subset of the CPUs, please consult
+       the arm,gic-v3 binding for details on describing a PPI partition.
+    maxItems: 1
+
+required:
+  - compatible
+  - interrupts
+
+additionalProperties: false
+
+examples:
+
+  - |
+   #include <dt-bindings/interrupt-controller/arm-gic.h>
+
+   trbe {
+     compatible = "arm,trace-buffer-extension";
+     interrupts = <GIC_PPI 15 IRQ_TYPE_LEVEL_HIGH>;
+   };
+...
-- 
2.7.4

Re: [PATCH V3 12/14] dts: bindings: Document device tree bindings for Arm TRBE

[Rob Herring]

On Wed, 27 Jan 2021 14:25:36 +0530, Anshuman Khandual wrote:
> From: Suzuki K Poulose <suzuki.poulose@arm.com>
> 
> Document the device tree bindings for Trace Buffer Extension (TRBE).
> 
> Cc: Anshuman Khandual <anshuman.khandual@arm.com>
> Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
> Cc: Rob Herring <robh@kernel.org>
> Cc: devicetree@vger.kernel.org
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
> ---
> Changes in V3:
> 
> - Added missing description for the TRBE hardware
> - Fixed all DT yaml semantics problems
> 
>  Documentation/devicetree/bindings/arm/trbe.yaml | 49 +++++++++++++++++++++++++
>  1 file changed, 49 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/arm/trbe.yaml
> 

Reviewed-by: Rob Herring <robh@kernel.org>