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authorHoulong Wei <houlong.wei@mediatek.com>2018-07-25 04:26:39 +0300
committerJassi Brar <jaswinder.singh@linaro.org>2018-08-03 17:22:14 +0300
commit1c82407aa302774b24bf619e56973aa97cbf25bd (patch)
tree1daa665747a50d0a8c88eea4da5266755f61d804 /Documentation/devicetree/bindings/mailbox
parenta2b79838b891718dd4f0caf86dfa193af789245d (diff)
downloadlinux-1c82407aa302774b24bf619e56973aa97cbf25bd.tar.xz
dt-bindings: soc: Add documentation for the MediaTek GCE unit
This adds documentation for the MediaTek Global Command Engine (GCE) unit found in MT8173 SoCs. Signed-off-by: Houlong Wei <houlong.wei@mediatek.com> Signed-off-by: HS Liao <hs.liao@mediatek.com> Reviewed-by: Rob Herring <robh@kernel.org> Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>
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+MediaTek GCE
+===============
+
+The Global Command Engine (GCE) is used to help read/write registers with
+critical time limitation, such as updating display configuration during the
+vblank. The GCE can be used to implement the Command Queue (CMDQ) driver.
+
+CMDQ driver uses mailbox framework for communication. Please refer to
+mailbox.txt for generic information about mailbox device-tree bindings.
+
+Required properties:
+- compatible: Must be "mediatek,mt8173-gce"
+- reg: Address range of the GCE unit
+- interrupts: The interrupt signal from the GCE block
+- clock: Clocks according to the common clock binding
+- clock-names: Must be "gce" to stand for GCE clock
+- #mbox-cells: Should be 3.
+ <&phandle channel priority atomic_exec>
+ phandle: Label name of a gce node.
+ channel: Channel of mailbox. Be equal to the thread id of GCE.
+ priority: Priority of GCE thread.
+ atomic_exec: GCE processing continuous packets of commands in atomic
+ way.
+
+Required properties for a client device:
+- mboxes: Client use mailbox to communicate with GCE, it should have this
+ property and list of phandle, mailbox specifiers.
+- mediatek,gce-subsys: u32, specify the sub-system id which is corresponding
+ to the register address.
+
+Some vaules of properties are defined in 'dt-bindings/gce/mt8173-gce.h'. Such as
+sub-system ids, thread priority, event ids.
+
+Example:
+
+ gce: gce@10212000 {
+ compatible = "mediatek,mt8173-gce";
+ reg = <0 0x10212000 0 0x1000>;
+ interrupts = <GIC_SPI 135 IRQ_TYPE_LEVEL_LOW>;
+ clocks = <&infracfg CLK_INFRA_GCE>;
+ clock-names = "gce";
+ thread-num = CMDQ_THR_MAX_COUNT;
+ #mbox-cells = <3>;
+ };
+
+Example for a client device:
+
+ mmsys: clock-controller@14000000 {
+ compatible = "mediatek,mt8173-mmsys";
+ mboxes = <&gce 0 CMDQ_THR_PRIO_LOWEST 1>,
+ <&gce 1 CMDQ_THR_PRIO_LOWEST 1>;
+ mediatek,gce-subsys = <SUBSYS_1400XXXX>;
+ mutex-event-eof = <CMDQ_EVENT_MUTEX0_STREAM_EOF
+ CMDQ_EVENT_MUTEX1_STREAM_EOF>;
+
+ ...
+ };