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Diffstat (limited to 'Documentation/devicetree/bindings/clock/mediatek,mt8196-sys-clock.yaml')
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diff --git a/Documentation/devicetree/bindings/clock/mediatek,mt8196-sys-clock.yaml b/Documentation/devicetree/bindings/clock/mediatek,mt8196-sys-clock.yaml new file mode 100644 index 000000000000..660ab64f390d --- /dev/null +++ b/Documentation/devicetree/bindings/clock/mediatek,mt8196-sys-clock.yaml @@ -0,0 +1,107 @@ +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause) +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/clock/mediatek,mt8196-sys-clock.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: MediaTek System Clock Controller for MT8196 + +maintainers: + - Guangjie Song <guangjie.song@mediatek.com> + - Laura Nao <laura.nao@collabora.com> + +description: | + The clock architecture in MediaTek SoCs is structured like below: + PLLs --> + dividers --> + muxes + --> + clock gate + + The apmixedsys, apmixedsys_gp2, vlpckgen, armpll, ccipll, mfgpll and ptppll + provide most of the PLLs which are generated from the SoC's 26MHZ crystal oscillator. + The topckgen, topckgen_gp2 and vlpckgen provide dividers and muxes which + provide the clock source to other IP blocks. + +properties: + compatible: + items: + - enum: + - mediatek,mt8196-apmixedsys + - mediatek,mt8196-armpll-b-pll-ctrl + - mediatek,mt8196-armpll-bl-pll-ctrl + - mediatek,mt8196-armpll-ll-pll-ctrl + - mediatek,mt8196-apmixedsys-gp2 + - mediatek,mt8196-ccipll-pll-ctrl + - mediatek,mt8196-mfgpll-pll-ctrl + - mediatek,mt8196-mfgpll-sc0-pll-ctrl + - mediatek,mt8196-mfgpll-sc1-pll-ctrl + - mediatek,mt8196-ptppll-pll-ctrl + - mediatek,mt8196-topckgen + - mediatek,mt8196-topckgen-gp2 + - mediatek,mt8196-vlpckgen + - const: syscon + + reg: + maxItems: 1 + + '#clock-cells': + const: 1 + + mediatek,hardware-voter: + $ref: /schemas/types.yaml#/definitions/phandle + description: | + Phandle to the "Hardware Voter" (HWV), as named in the vendor + documentation for MT8196/MT6991. + + The HWV is a SoC-internal fixed-function MCU used to collect votes from + both the Application Processor and other remote processors within the SoC. + It is intended to transparently enable or disable hardware resources (such + as power domains or clocks) based on internal vote aggregation handled by + the MCU's internal state machine. + + However, in practice, this design is incomplete. While the HWV performs + some internal vote aggregation,software is still required to + - Manually enable power supplies externally, if present and if required + - Manually enable parent clocks via direct MMIO writes to clock controllers + - Enable the FENC after the clock has been ungated via direct MMIO + writes to clock controllers + + As such, the HWV behaves more like a hardware-managed clock reference + counter than a true voter. Furthermore, it is not a separate + controller. It merely serves as an alternative interface to the same + underlying clock or power controller. Actual control still requires + direct access to the controller's own MMIO register space, in + addition to writing to the HWV's MMIO region. + + For this reason, a custom phandle is used here - drivers need to directly + access the HWV MMIO region in a syscon-like fashion, due to how the + hardware is wired. This differs from true hardware voting systems, which + typically do not require custom phandles and rely instead on generic APIs + (clocks, power domains, interconnects). + + The name "hardware-voter" is retained to match vendor documentation, but + this should not be reused or misunderstood as a proper voting mechanism. + +required: + - compatible + - reg + - '#clock-cells' + +additionalProperties: false + +examples: + - | + apmixedsys_clk: syscon@10000800 { + compatible = "mediatek,mt8196-apmixedsys", "syscon"; + reg = <0x10000800 0x1000>; + #clock-cells = <1>; + }; + - | + topckgen: syscon@10000000 { + compatible = "mediatek,mt8196-topckgen", "syscon"; + reg = <0x10000000 0x800>; + mediatek,hardware-voter = <&scp_hwv>; + #clock-cells = <1>; + }; + |