Re: [PATCH V2 06/11] dts: bindings: Document device tree bindings for ETE
From: Suzuki K Poulose
Date: Mon Jan 25 2021 - 18:30:39 EST
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@xxxxxxx>
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@xxxxxxxxxxxxxxx
Cc: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
Cc: Mike Leach <mike.leach@xxxxxxxxxx>
Cc: Rob Herring <robh@xxxxxxxxxx>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
---
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@xxxxxxx>
+ - Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
+
+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