This binding provides interface for adding values related to ASPEED AST2400/2500 PWM and Fan tach controller support. The PWM controller can support upto 8 PWM output ports. The Fan tach controller can support upto 16 tachometer inputs. Types M, N and 0 are three types just to have three independent PWM/Fan Tach related settings. Signed-off-by: Jaghathiswari Rankappagounder Natarajan <jaghu@xxxxxxxxxx> --- v2: - Removed '_' in node or property names - Gave some explanation for the properties used. .../devicetree/bindings/hwmon/aspeed-pwm-tacho.txt | 178 +++++++++++++++++++++ 1 file changed, 178 insertions(+) create mode 100644 Documentation/devicetree/bindings/hwmon/aspeed-pwm-tacho.txt 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 000000000000..290122bfe170 --- /dev/null +++ b/Documentation/devicetree/bindings/hwmon/aspeed-pwm-tacho.txt @@ -0,0 +1,178 @@ +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 tachometer inputs. + +There are three different types M, N, O. These three types are just to have +different PWM and Fan Tach settings. Each type can have the following settings: + PWM related: + 1) PWM period + 2) PWM clock division high + 3) PWM clock division low + Fan Tach related: + 1) Fan Tach type enable + 2) Fan Tach clock division + 3) Fan Tach mode selection + 4) Fan Tach period + +Each PWM port should be assigned a type which can be type M, N or O. + +Each Fan Tach channel should be assigned a PWM source, which can be PWM port A +through H. The Fan Tach channel implicitly gets the type (M, N or O), from the +type assigned to its PWM source. + +Required properties for pwm-tacho node: +- #address-cells : should be 1. + +- #size-cells : should be 1. + +- 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 AST2400/AST2500 PWM + ports. + +- compatible : should be "aspeed,aspeed2400-pwm-tacho" for AST2400 or + "aspeed,aspeed2500-pwm-tacho" for AST2500. + +- clocks : a fixed clock providing input clock frequency(PWM + and Fan Tach clock) + +type-values subnode format: +=========================== +Under type-values subnode there can be upto 3 child nodes indicating type M/N/O +values. Atleast one child node is required. + +Required properties for the child node(type M/N/O): +- type : indicates type M/N/O. integer value in the range 0 to 2 with 0 + indicating type M, 1 indicating type N and 2 indicating type O. + +- pwm-period : indicates type M/N/O PWM period, as per the AST2400/AST2500 + datasheet. integer value in the range 0 to 255. + +- pwm-clock-division-l : indicates type M/N/O PWM clock division L value, + as per the AST2400/AST2500 datasheet. + integer value in the range 0 to 15. + 0 here indicates divide 1, 1 indicates divide 2, + 2 indicates divide 4, 3 indicates divide 6, and so on + till 15 indicates divide 30. + +- pwm-clock-division-h : indicates type M/N/O PWM clock division H value, + as per the AST2400/AST2500 datasheet. + integer value in the range 0 to 15. + 0 here indicates divide 1, 1 indicates divide 2, + 2 indicates divide 4, 3 indicates divide 8, and so on + till 15 indicates divide 32768. + +- fan-tach-type-enable : indicates fan tach enable of type M/N/O as per the + AST2400/AST2500 datasheet. boolean value. + +- fan-tach-clock-division : indicates fan tach clock division as per the + AST2400/AST2500 datasheet. + integer value in the range 0 to 7. + 0 indicates divide 4, 1 indicates divide 16, + 2 indicates divide 64, 3 indicates divide 256 + and so on till 7 indicates divide 65536. + +- fan-tach-mode-selection : indicates fan tach mode mode selection as per the + AST2400/AST2500 datasheet. integer value in the + range 0 to 2. 0 indicates falling edge, 1 indicates + rising edge and 2 indicates both edges. + +- fan-tach-period : indicates fan tach period as per the AST2400/AST2500 + datasheet. integer value (can be upto 16 bits long). + +pwm-port subnode format: +======================== +Under pwm-port subnode there can upto 8 child nodes each indicating values +for one of the 8 PWM output ports. + +Required properties for each child node(starting from PWM A through PWM H): +- pwm-port : should specify PWM #X port , X ranges from A through H. + integer value in the range 0 to 7 with 0 indicating PWM port + A and 7 indicating PWM port H. + +- type : indicates type selection value of PWM port. integer value in the + range 0 to 2; 0 indicates type M, 1 indicates type N, 2 indicates + type O. + +- fan-ctrl : set the PWM duty cycle initial value. integer value between + 0(off) and 255(full speed). + +fan-tach-channel subnode format: +================================ +Under fan-tach-channel subnode there can be upto 16 child nodes each indicating +values for one of the 16 fan tach channels. + +Required properties for each child node(starting from fan tach #0 through +fan tach #15): +- fan-ctrl-gpios : should specify the tachometer input GPIO pin on the hardware. + Fan Tachometer function can only work when GPIO is in + ”input mode” + +- fan-tach : should specify the fan tach channel #X, X ranges from 0 through + 15. integer value in the range 0 through 15. + +- pwm-source : indicates PWM source of the fan tach channel. integer value in + the range 0 to 7. 0 indicates PWM port A, 1 indicates PWM + port B and so on till 7 indicates PWM port H. + +Examples: + +pwm-tacho-fixed-clk: fixedclk { + compatible = "fixed-clock"; + #clock-cells = <0>; + clock-frequency = <24000000>; +} + +pwm-tacho: pwm-tacho-controller@1e786000 { + #address-cells = <1>; + #size-cells = <1>; + reg = <0x1E786000 0x1000>; + pinctrl-names = "default"; + pinctrl-0 = <&pinctrl_pwm0_default &pinctrl_pwm1_default>; + compatible = "aspeed,aspeed2500-pwm-tacho"; + clocks = <&pwm-tacho-fixed-clk>; + type-values { + typem { + type = /bits/ 8 <0x00>; + pwm-period = /bits/ 8 <0x5F>; + pwm-clock-division-h = /bits/ 8 <0x00>; + pwm-clock-division-l = /bits/ 8 <0x05>; + fan-tach-type-enable; + fan-tach-clock-division = /bits/ 8 <0x00>; + fan-tach-mode-selection = /bits/ 8 <0x00>; + fan-tach-period = /bits/ 16 <0x1000>; + }; + }; + + pwm-port { + pwm-port0 { + pwm-port = /bits/ 8 <0x00>; + type = /bits/ 8 <0x00>; + fan-ctrl = /bits/ 8 <0xFF>; + }; + + pwm-port1 { + pwm-port = /bits/ 8 <0x01>; + type = /bits/ 8 <0x00>; + fan-ctrl = /bits/ 8 <0xFF>; + }; + }; + + fan-tach-channel { + fan-tach0 { + fan-ctrl-gpios = <&gpio ASPEED_GPIO(O, 0) GPIO_ACTIVE_HIGH>; + fan-tach = /bits/ 8 <0x00>; + pwm-source = /bits/ 8 <0x00>; + }; + + fan-tach1 { + fan-ctrl-gpios = <&gpio ASPEED_GPIO(O, 1) GPIO_ACTIVE_HIGH>; + fan-tach = /bits/ 8 <0x01>; + pwm-source = /bits/ 8 <0x01>; + }; + + }; +}; -- 2.11.0.483.g087da7b7c-goog -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html