This documents a device tree binding for the Qualcomm Shared Memory
State Machine.
Signed-off-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxxxxxx>
---
Changes since v1:
- No longer representing outgoing state as gpio-controller
.../devicetree/bindings/soc/qcom/qcom,smsm.txt | 104 +++++++++++++++++++++
1 file changed, 104 insertions(+)
create mode 100644 Documentation/devicetree/bindings/soc/qcom/qcom,smsm.txt
diff --git a/Documentation/devicetree/bindings/soc/qcom/qcom,smsm.txt b/Documentation/devicetree/bindings/soc/qcom/qcom,smsm.txt
new file mode 100644
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@@ -0,0 +1,104 @@
+Qualcomm Shared Memory State Machine
+
+The Shared Memory State Machine facilitates broadcasting of single bit state
+information between the processors in a Qualcomm SoC. Each processor is
+assigned 32 bits of state that can be modified. A processor can through a
+matrix of bitmaps signal subscription of notifications upon changes to a
+certain bit owned by a certain remote processor.
+
+- compatible:
+ Usage: required
+ Value type: <string>
+ Definition: must be one of:
+ "qcom,smsm"
+
+- qcom,ipc-N:
+ Usage: required
+ Value type: <prop-encoded-array>
+ Definition: three entries specifying the outgoing ipc bit used for
+ signaling the N:th 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,local-host:
+ Usage: optional
+ Value type: <u32>
+ Definition: identifier of the local processor in the list of hosts, or
+ in other words specifier of the column in the subscription
+ matrix representing the local processor
+ defaults to host 0
+
+- #address-cells:
+ Usage: required
+ Value type: <u32>
+ Definition: must be 1
+
+- #size-cells:
+ Usage: required
+ Value type: <u32>
+ Definition: must be 0
+
+= SUBNODES
+Each processor's state bits are described by a subnode of the smsm device node.
+Nodes can either be flagged as an interrupt-controller to denote a remote
+processor's state bits or the local processors bits. The node names are not
+important.
+
+- reg:
+ Usage: required
+ Value type: <u32>
+ Definition: specifies the offset, in words, of the first bit for this
+ entry
+
+- #qcom,state-cells:
+ Usage: required for local entry
+ Value type: <u32>
+ Definition: must be 1 - denotes bit number
+
+- interrupt-controller:
+ Usage: required for remote entries
+ Value type: <empty>
+ Definition: marks the entry as a interrupt-controller and the state bits
+ to belong to a remote processor
+
+- #interrupt-cells:
+ Usage: required for remote entries
+ Value type: <u32>
+ Definition: must be 2 - denotes bit number and IRQ flags
+
+- interrupts:
+ Usage: required for remote entries
+ Value type: <prop-encoded-array>
+ Definition: one entry specifying remote IRQ used by the remote processor
+ to signal changes of its state bits
+
+
+= EXAMPLE
+The following example shows the SMEM setup for controlling properties of the
+wireless processor, defined from the 8974 apps processor's point-of-view. It
+encompasses one outbound entry and the outgoing interrupt for the wireless
+processor.
+
+smsm {
+ compatible = "qcom,smsm";
+
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ qcom,ipc-3 = <&apcs 8 19>;
+
+ apps_smsm: apps@0 {
+ reg = <0>;
+
+ #qcom,state-cells = <1>;
+ };
+
+ wcnss_smsm: wcnss@7 {
+ reg = <7>;
+ interrupts = <0 144 1>;
+
+ interrupt-controller;
+ #interrupt-cells = <2>;
+ };
+};
--
1.8.2.2
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