65 lines
2.4 KiB
Plaintext
65 lines
2.4 KiB
Plaintext
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MediaTek GCE
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===============
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The Global Command Engine (GCE) is used to help read/write registers with
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critical time limitation, such as updating display configuration during the
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vblank. The GCE can be used to implement the Command Queue (CMDQ) driver.
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CMDQ driver uses mailbox framework for communication. Please refer to
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mailbox.txt for generic information about mailbox device-tree bindings.
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Required properties:
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- compatible: can be "mediatek,mt8173-gce" or "mediatek,mt8183-gce"
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- reg: Address range of the GCE unit
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- interrupts: The interrupt signal from the GCE block
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- clock: Clocks according to the common clock binding
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- clock-names: Must be "gce" to stand for GCE clock
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- #mbox-cells: Should be 3.
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<&phandle channel priority atomic_exec>
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phandle: Label name of a gce node.
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channel: Channel of mailbox. Be equal to the thread id of GCE.
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priority: Priority of GCE thread.
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atomic_exec: GCE processing continuous packets of commands in atomic
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way.
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Required properties for a client device:
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- mboxes: Client use mailbox to communicate with GCE, it should have this
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property and list of phandle, mailbox specifiers.
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Optional properties for a client device:
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- mediatek,gce-client-reg: Specify the sub-system id which is corresponding
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to the register address, it should have this property and list of phandle,
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sub-system specifiers.
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<&phandle subsys_number start_offset size>
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phandle: Label name of a gce node.
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subsys_number: specify the sub-system id which is corresponding
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to the register address.
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start_offset: the start offset of register address that GCE can access.
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size: the total size of register address that GCE can access.
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Some vaules of properties are defined in 'dt-bindings/gce/mt8173-gce.h'
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or 'dt-binding/gce/mt8183-gce.h'. Such as sub-system ids, thread priority, event ids.
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Example:
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gce: gce@10212000 {
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compatible = "mediatek,mt8173-gce";
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reg = <0 0x10212000 0 0x1000>;
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interrupts = <GIC_SPI 135 IRQ_TYPE_LEVEL_LOW>;
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clocks = <&infracfg CLK_INFRA_GCE>;
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clock-names = "gce";
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#mbox-cells = <3>;
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};
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Example for a client device:
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mmsys: clock-controller@14000000 {
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compatible = "mediatek,mt8173-mmsys";
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mboxes = <&gce 0 CMDQ_THR_PRIO_LOWEST 1>,
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<&gce 1 CMDQ_THR_PRIO_LOWEST 1>;
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mutex-event-eof = <CMDQ_EVENT_MUTEX0_STREAM_EOF
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CMDQ_EVENT_MUTEX1_STREAM_EOF>;
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mediatek,gce-client-reg = <&gce SUBSYS_1400XXXX 0x3000 0x1000>,
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<&gce SUBSYS_1401XXXX 0x2000 0x100>;
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...
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};
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