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Subject[PATCH v2 08/10] coresight: dts: Document usage of graph bindings
Before we update the bindings, document the current graph bindings
and usage of additional properties.

Reviewed-by: Mathieu Poirier <>
Signed-off-by: Suzuki K Poulose <>
.../devicetree/bindings/arm/coresight.txt | 30 +++++++++++++++++++---
1 file changed, 26 insertions(+), 4 deletions(-)

diff --git a/Documentation/devicetree/bindings/arm/coresight.txt b/Documentation/devicetree/bindings/arm/coresight.txt
index 5d1ad09..8e21512 100644
--- a/Documentation/devicetree/bindings/arm/coresight.txt
+++ b/Documentation/devicetree/bindings/arm/coresight.txt
@@ -54,9 +54,7 @@ its hardware characteristcs.
clocks the core of that coresight component. The latter clock
is optional.

- * port or ports: The representation of the component's port
- layout using the generic DT graph presentation found in
- "bindings/graph.txt".
+ * port or ports: see "Graph bindings for Coresight" below.

* Additional required properties for System Trace Macrocells (STM):
* reg: along with the physical base address and length of the register
@@ -73,7 +71,7 @@ its hardware characteristcs.
AMBA markee):
- "arm,coresight-replicator"

- * port or ports: same as above.
+ * port or ports: see "Graph bindings for Coresight" below.

* Optional properties for ETM/PTMs:

@@ -96,6 +94,30 @@ its hardware characteristcs.
* interrupts : Exactly one SPI may be listed for reporting the address

+Graph bindings for Coresight
+Coresight components are interconnected to create a data path for the flow of
+trace data generated from the "sources" to their collection points "sink".
+Each coresight component must describe the "input" and "output" connections.
+The connections must be described via generic DT graph bindings as described
+by the "bindings/graph.txt", where each "port" along with an "endpoint"
+component represents a hardware port and the connection.
+Since it is possible to have multiple connections for any coresight component
+with a specific direction of data flow, each connection must define the
+following properties to uniquely identify the connection details.
+ * Direction of the data flow w.r.t the component :
+ Each input port must have the following property defined at the "endpoint"
+ for the port.
+ "slave-mode"
+ * Hardware Port number at the component:
+ - The hardware port number is assumed to be the address of the "port"
+ component.

1. Sinks
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