Add device tree binding documentation for the Qualcomm Shared Memory
Device.
Signed-off-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxxxxxx>
---
I was looking at having one smd node per remote processor - e.g flatten the
first and second level. As all the channels, for all the remote processors are
allocated from the same pool this does however not feel very natural.
.../devicetree/bindings/soc/qcom/qcom,smd.txt | 82 ++++++++++++++++++++
1 file changed, 82 insertions(+)
create mode 100644 Documentation/devicetree/bindings/soc/qcom/qcom,smd.txt
diff --git a/Documentation/devicetree/bindings/soc/qcom/qcom,smd.txt b/Documentation/devicetree/bindings/soc/qcom/qcom,smd.txt
new file mode 100644
index 0000000..c56e4fc
--- /dev/null
+++ b/Documentation/devicetree/bindings/soc/qcom/qcom,smd.txt
@@ -0,0 +1,82 @@
+Qualcomm Shared Memory Driver (SMD) binding
+
+This binding describes the Qualcomm Shared Memory Driver, a fifo based
+communication channel for sending data between the various subsystems in
+Qualcomm platforms.
+
+- compatible:
+ Usage: required
+ Value type: <stringlist>
+ Definition: must be "qcom,smd"
+
+- qcom,smem:
+ Usage: required
+ Value type: <prop-encoded-array>
+ Definition: reference to a smem node managing the shared memory items
+ used for smd
+
+= EDGES
+
+Each subnode of the SMD node represents a remote subsystem, i.e. a remote
+processor of some sort - in SMD language called an "edge". The name of the
+edges are not important.
+
+- interrupts:
+ Usage: required
+ Value type: <prop-encoded-array>
+ Definition: should specify the IRQ used by the remote processor to
+ signal this processor about communication related updates
+
+- qcom,ipc:
+ Usage: required
+ Value type: <prop-encoded-array>
+ Definition: three entries specifying the outgoing ipc bit used for
+ signaling the remote processor:
+ - phandle to a syscon node representing the apcs registers
+ - u32 representing offset to the register within the syscon
+ - u32 representing the ipc bit within the register
+
+- qcom,smd-edge:
+ Usage: required
+ Value type: <u32>
+ Definition: an identifier representing the remote processor
+
+= SMD DEVICES
+
+In turn, subnodes of the "edges" represent devices tied to SMD channels on that
+"edge". The names of the devices are not important. The properties of these
+nodes are defined by the individual bindings for the SMD devices - but must
+contain the following property:
+
+- qcom,smd-channels:
+ Usage: required
+ Value type: <stringlist>
+ Definition: a list of channels tied to this device, used for matching
+ the device to channels
+
+= EXAMPLE
+
+The following example represents a smd node, with one edge representing the
+"rpm" subsystem. For the "rpm" subsystem we have a device tied to the
+"rpm_request" channel.
+
+ smd {
+ compatible = "qcom,smd";
+ qcom,smem = <&smem>;
+
+ rpm {
+ interrupts = <0 168 1>;
+ qcom,ipc = <&apcs 8 0>;
+ qcom,smd-edge = <15>;
+
+ rpm_requests {
+ compatible = "qcom,rpm-msm8974";
+ qcom,smd-channels = "rpm_requests";
+
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ ...
+ };
+ };
+ };
--
1.7.9.5
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