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| -rw-r--r-- | Documentation/devicetree/bindings/hwmon/aspeed-pwm-tacho.txt | 73 |
1 files changed, 73 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/hwmon/aspeed-pwm-tacho.txt b/Documentation/devicetree/bindings/hwmon/aspeed-pwm-tacho.txt new file mode 100644 index 000000000..3ac02988a --- /dev/null +++ b/Documentation/devicetree/bindings/hwmon/aspeed-pwm-tacho.txt @@ -0,0 +1,73 @@ +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>; + }; +}; |