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dt-bindings: add mmio-based syscon mux controller DT bindings
This adds device tree binding documentation for mmio-based syscon multiplexers controlled by a bitfields in a syscon register range. Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de> Acked-by: Rob Herring <robh@kernel.org> Signed-off-by: Peter Rosin <peda@axentia.se> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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MMIO register bitfield-based multiplexer controller bindings | ||
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Define register bitfields to be used to control multiplexers. The parent | ||
device tree node must be a syscon node to provide register access. | ||
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Required properties: | ||
- compatible : "mmio-mux" | ||
- #mux-control-cells : <1> | ||
- mux-reg-masks : an array of register offset and pre-shifted bitfield mask | ||
pairs, each describing a single mux control. | ||
* Standard mux-controller bindings as decribed in mux-controller.txt | ||
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Optional properties: | ||
- idle-states : if present, the state the muxes will have when idle. The | ||
special state MUX_IDLE_AS_IS is the default. | ||
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The multiplexer state of each multiplexer is defined as the value of the | ||
bitfield described by the corresponding register offset and bitfield mask pair | ||
in the mux-reg-masks array, accessed through the parent syscon. | ||
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Example: | ||
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syscon { | ||
compatible = "syscon"; | ||
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mux: mux-controller { | ||
compatible = "mmio-mux"; | ||
#mux-control-cells = <1>; | ||
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mux-reg-masks = <0x3 0x30>, /* 0: reg 0x3, bits 5:4 */ | ||
<0x3 0x40>, /* 1: reg 0x3, bit 6 */ | ||
idle-states = <MUX_IDLE_AS_IS>, <0>; | ||
}; | ||
}; | ||
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video-mux { | ||
compatible = "video-mux"; | ||
mux-controls = <&mux 0>; | ||
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ports { | ||
/* inputs 0..3 */ | ||
port@0 { | ||
reg = <0>; | ||
}; | ||
port@1 { | ||
reg = <1>; | ||
}; | ||
port@2 { | ||
reg = <2>; | ||
}; | ||
port@3 { | ||
reg = <3>; | ||
}; | ||
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/* output */ | ||
port@4 { | ||
reg = <4>; | ||
}; | ||
}; | ||
}; |