Subject: [PATCH linux v2 1/2] Documentation: dt-bindings: Document bindings for
ASPEED AST2400/AST2500 PWM and Fan tach controller device driver

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@google.com>
- ---
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
+ ΓÇ¥input modeΓÇ¥
+
+- 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

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