On Fri, Jan 27, 2017 at 1:32 AM, Jaghathiswari Rankappagounder Natarajan <jaghu@xxxxxxxxxx> wrote: > > > On Fri, Jan 13, 2017 at 8:21 AM, Rob Herring <robh@xxxxxxxxxx> wrote: >> >> On Mon, Jan 09, 2017 at 01:59:34PM -0800, Jaghathiswari Rankappagounder >> Natarajan wrote: >> > 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. >> > PWM clock types M, N and 0 are three types just to have three >> > independent >> > PWM sources. >> > >> > Signed-off-by: Jaghathiswari Rankappagounder Natarajan >> > <jaghu@xxxxxxxxxx> >> > --- >> > .../devicetree/bindings/hwmon/aspeed-pwm-tacho.txt | 153 >> > +++++++++++++++++++++ >> >> Perhaps bindings/pwm/... even though this is more than just PWM. > > The corresponding hwmon driver is present in /drivers/hwmon/. So would it > make more > > sense to include the devicetree document for that driver in > /devicetree/bindings/hwmon/. > > In future if there any more hwmon related functionalities are added to this > driver then /devicetree/bindings/hwmon/ would be more relevant. > > >> >> >> > 1 file changed, 153 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..8f346409ee8c >> > --- /dev/null >> > +++ b/Documentation/devicetree/bindings/hwmon/aspeed-pwm-tacho.txt >> > @@ -0,0 +1,153 @@ >> > +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. The PWM controller >> > supports >> > +3 types of frequency mode PWM for fan speed control. PWM clock types M, >> > N and 0 >> > +are 3 types of frequency mode PWM just to have 3 independent PWM >> > sources. >> > + >> > +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: >> >> Don't use '_' in node or property names. > > Done. >> >> >> > +=========================== >> > +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): >> > +- 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. >> >> Can't you have a single divider value and driver convert to register >> values? Really, you should specify the PWM period in ns/us and calculate >> the divider based on the input clock freq. (i.e. use the clock binding). >> There's already PWM binding to specify the period. >> >> I think you should have a node for the fan using the PWM binding and >> perhaps moving some of these properties to the fan node. > > > There are three different types M, N, O. These three types are just to have > > different PWM/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. > > If the clock type is type M then : > The PWM frequency = 24MHz / (type M clock division L value * type M clock > division H value * > > (type M PWM period value + 1)) > > Because of this formula, I thought I could use properties to specify type > clock division High and Low and > > type period values so that the desired PWM frequency be achieved. >> >> >> > + >> > +- fan_tach_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): >> > +- enable : enable PWM #X port, X ranges from A through H. boolean >> > value. >> >> A connection in the PWM binding would imply this. > > Had to change this property to indicate PWM port number. > > >> >> >> > + >> > +- type : indicates type selection value of PWM #X port, X ranges from A >> > + through H. integer value in the range 0 to 2; >> > + 0 indicates type M, 1 indicates type N, 2 indicates type O. >> >> This is meaningless to me. > > > Each PWM port should be assigned a type which can be type M, N or O. > > >> >> >> > +- fan_ctrl : set the PWM fan control 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 #16): >> > +- fan-ctrl-gpios : should specify the tachometer input pin on the >> > hardware. >> >> I don't understand the connection here. You have a tach block with 16 >> inputs on the SoC, so why the GPIOs? If the GPIOs go to the fan, then a >> fan node should have the GPIO properties. > > This property specifies the tachometer input GPIO pin on the hardware. Fan > Tachometer function > > can only work when GPIO is in ”input mode” . >> >> >> > + >> > +- enable : enable fan tach #X, X ranges from 0 through 16. boolean >> > value. >> >> 'status' property is the standard way to enable a node or not. Not sure >> if that makes sense here though. > > Had to change this property to indicate Fan tach channel number. > > >> >> >> > + >> > +- pwm_source : indicates PWM source of fan tach #X, X ranges from 0 >> > through 16. >> > + 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. > > -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
