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