Add device tree binding documentation for the Qualcomm Shared Memory
Device, used for communication between the various CPUs in the Qualcomm
SoCs.
Signed-off-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxxxxxx>
---
No changes since v2
.../devicetree/bindings/soc/qcom/qcom,smd.txt | 79 ++++++++++++++++++++++
1 file changed, 79 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 000000000000..f65c76db9859
--- /dev/null
+++ b/Documentation/devicetree/bindings/soc/qcom/qcom,smd.txt
@@ -0,0 +1,79 @@
+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"
+
+= EDGES
+
+Each subnode of the SMD node represents a remote subsystem or a remote
+processor of some sort - or in SMD language an "edge". The name of the edges
+are not important.
+The edge is described by the following properties:
+
+- 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: the identifier of the remote processor in the smd channel
+ allocation table
+
+= 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.
+
+ apcs: syscon@f9011000 {
+ compatible = "syscon";
+ reg = <0xf9011000 0x1000>;
+ };
+
+ smd {
+ compatible = "qcom,smd";
+
+ 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";
+
+ ...
+ };
+ };
+ };
--
1.8.2.2
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