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Add documentation for the mt6779 gce. Add gce header file defined the gce hardware event, subsys number and constant for mt6779. Signed-off-by: Dennis YC Hsieh <dennis-yc.hsieh@mediatek.com> Reviewed-by: Rob Herring <robh@kernel.org> Reviewed-by: CK Hu <ck.hu@mediatek.com> Reviewed-by: Bibby Hsieh <bibby.hsieh@mediatek.com> Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>
65 lines
2.4 KiB
Plaintext
65 lines
2.4 KiB
Plaintext
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", "mediatek,mt8183-gce" or
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"mediatek,mt6779-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 2.
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<&phandle channel priority>
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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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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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'dt-binding/gce/mt8183-gce.h' or 'dt-bindings/gce/mt6779-gce.h'. Such as
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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>,
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<&gce 1 CMDQ_THR_PRIO_LOWEST>;
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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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