Re: [PATCH v4 15/19] dts: bindings: Document device tree bindings for ETE

From: Mike Leach <mike.leach@linaro.org>
To: Rob Herring <robh@kernel.org>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Mathieu Poirier <mathieu.poirier@linaro.org>,
	Anshuman Khandual <anshuman.khandual@arm.com>,
	Leo Yan <leo.yan@linaro.org>,
	devicetree@vger.kernel.org
Subject: Re: [PATCH v4 15/19] dts: bindings: Document device tree bindings for ETE
Date: Mon, 8 Mar 2021 17:25:57 +0000	[thread overview]
Message-ID: <CAJ9a7Vgw5-kR7HJ+HzQ=rK41BOxhi5jOO7N+85kbxuDzzNO=-A@mail.gmail.com> (raw)
In-Reply-To: <20210306210627.GA1207387@robh.at.kernel.org>

Hi Suzuki

Need to add this file and the TRBE bindings file to the ARM/CORESIGHT
section of the MAINTAINERS file.

Regards

Mike

On Sat, 6 Mar 2021 at 21:06, Rob Herring <robh@kernel.org> wrote:
>
> On Thu, Feb 25, 2021 at 07:35:39PM +0000, Suzuki K Poulose wrote:
> > 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>
> > ---
> > Changes:
> >  - Fix out-ports defintion
> > ---
> >  .../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 000000000000..35a42d92bf97
> > --- /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:
> > +    description: |
> > +      Handle to the cpu this ETE is bound to.
> > +    $ref: /schemas/types.yaml#/definitions/phandle
> > +
> > +  out-ports:
> > +    description: |
> > +      Output connections from the ETE to legacy CoreSight trace bus.
> > +    $ref: /schemas/graph.yaml#/properties/port
>
> s/port/ports/
>
> And then you need:
>
>        properties:
>          port:
>            description: what this port is
>            $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>;
> > +             };
> > +         };
> > +      };
> > +   };
> > +
> > +...
> > --
> > 2.24.1
> >

--
Mike Leach
Principal Engineer, ARM Ltd.
Manchester Design Centre. UK