[PATCH 1/2] soc: qcom: Add device tree binding for Shared Memory Device

[Bjorn Andersson]

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>
---
 .../devicetree/bindings/soc/qcom/qcom,smd.txt      | 78 ++++++++++++++++++++++
 1 file changed, 78 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..0fdb7f9d
--- /dev/null
+++ b/Documentation/devicetree/bindings/soc/qcom/qcom,smd.txt
@@ -0,0 +1,78 @@
+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.
+
+- 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 representing 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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