ASPEED AST2400/AST2500 PWM and Fan Tacho controller device driver
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The ASPEED PWM controller can support upto 8 PWM outputs. The ASPEED Fan Tacho
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controller can support upto 16 Fan tachometer inputs.
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There can be upto 8 fans supported. Each fan can have one PWM output and
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one/two Fan tach inputs.
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Required properties for pwm-tacho node:
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- #address-cells : should be 1.
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- #size-cells : should be 1.
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- #cooling-cells: should be 2.
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- reg : address and length of the register set for the device.
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- pinctrl-names : a pinctrl state named "default" must be defined.
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- pinctrl-0 : phandle referencing pin configuration of the PWM ports.
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- compatible : should be "aspeed,ast2400-pwm-tacho" for AST2400 and
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"aspeed,ast2500-pwm-tacho" for AST2500.
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- clocks : phandle to clock provider with the clock number in the second cell
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- resets : phandle to reset controller with the reset number in the second cell
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fan subnode format:
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===================
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Under fan subnode there can upto 8 child nodes, with each child node
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representing a fan. If there are 8 fans each fan can have one PWM port and
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one/two Fan tach inputs.
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For PWM port can be configured cooling-levels to create cooling device.
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Cooling device could be bound to a thermal zone for the thermal control.
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Required properties for each child node:
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- reg : should specify PWM source port.
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integer value in the range 0 to 7 with 0 indicating PWM port A and
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7 indicating PWM port H.
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- cooling-levels: PWM duty cycle values in a range from 0 to 255
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which correspond to thermal cooling states.
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- aspeed,fan-tach-ch : should specify the Fan tach input channel.
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integer value in the range 0 through 15, with 0 indicating
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Fan tach channel 0 and 15 indicating Fan tach channel 15.
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Atleast one Fan tach input channel is required.
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Examples:
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pwm_tacho: pwmtachocontroller@1e786000 {
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#address-cells = <1>;
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#size-cells = <1>;
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#cooling-cells = <2>;
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reg = <0x1E786000 0x1000>;
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compatible = "aspeed,ast2500-pwm-tacho";
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clocks = <&syscon ASPEED_CLK_APB>;
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resets = <&syscon ASPEED_RESET_PWM>;
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pinctrl-names = "default";
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pinctrl-0 = <&pinctrl_pwm0_default &pinctrl_pwm1_default>;
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fan@0 {
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reg = <0x00>;
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cooling-levels = /bits/ 8 <125 151 177 203 229 255>;
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aspeed,fan-tach-ch = /bits/ 8 <0x00>;
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};
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fan@1 {
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reg = <0x01>;
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aspeed,fan-tach-ch = /bits/ 8 <0x01 0x02>;
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};
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};
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