1ASPEED AST2400/AST2500 PWM and Fan Tacho controller device driver 2 3The ASPEED PWM controller can support upto 8 PWM outputs. The ASPEED Fan Tacho 4controller can support upto 16 Fan tachometer inputs. 5 6There can be upto 8 fans supported. Each fan can have one PWM output and 7one/two Fan tach inputs. 8 9Required properties for pwm-tacho node: 10- #address-cells : should be 1. 11 12- #size-cells : should be 1. 13 14- #cooling-cells: should be 2. 15 16- reg : address and length of the register set for the device. 17 18- pinctrl-names : a pinctrl state named "default" must be defined. 19 20- pinctrl-0 : phandle referencing pin configuration of the PWM ports. 21 22- compatible : should be "aspeed,ast2400-pwm-tacho" for AST2400 and 23 "aspeed,ast2500-pwm-tacho" for AST2500. 24 25- clocks : phandle to clock provider with the clock number in the second cell 26 27- resets : phandle to reset controller with the reset number in the second cell 28 29fan subnode format: 30=================== 31Under fan subnode there can upto 8 child nodes, with each child node 32representing a fan. If there are 8 fans each fan can have one PWM port and 33one/two Fan tach inputs. 34For PWM port can be configured cooling-levels to create cooling device. 35Cooling device could be bound to a thermal zone for the thermal control. 36 37Required properties for each child node: 38- reg : should specify PWM source port. 39 integer value in the range 0 to 7 with 0 indicating PWM port A and 40 7 indicating PWM port H. 41 42- cooling-levels: PWM duty cycle values in a range from 0 to 255 43 which correspond to thermal cooling states. 44 45- aspeed,fan-tach-ch : should specify the Fan tach input channel. 46 integer value in the range 0 through 15, with 0 indicating 47 Fan tach channel 0 and 15 indicating Fan tach channel 15. 48 At least one Fan tach input channel is required. 49 50Examples: 51 52pwm_tacho: pwmtachocontroller@1e786000 { 53 #address-cells = <1>; 54 #size-cells = <1>; 55 #cooling-cells = <2>; 56 reg = <0x1E786000 0x1000>; 57 compatible = "aspeed,ast2500-pwm-tacho"; 58 clocks = <&syscon ASPEED_CLK_APB>; 59 resets = <&syscon ASPEED_RESET_PWM>; 60 pinctrl-names = "default"; 61 pinctrl-0 = <&pinctrl_pwm0_default &pinctrl_pwm1_default>; 62 63 fan@0 { 64 reg = <0x00>; 65 cooling-levels = /bits/ 8 <125 151 177 203 229 255>; 66 aspeed,fan-tach-ch = /bits/ 8 <0x00>; 67 }; 68 69 fan@1 { 70 reg = <0x01>; 71 aspeed,fan-tach-ch = /bits/ 8 <0x01 0x02>; 72 }; 73}; 74