Message ID | 1436281613-899-7-git-send-email-lee.jones@linaro.org |
---|---|
State | Accepted, archived |
Commit | 02258b8bcbb98b28064cc829f7062455da398633 |
Headers | show |
Hi Lee, On Tue, 7 Jul 2015 16:06:50 +0100 Lee Jones <lee.jones@linaro.org> wrote: > * Add support for continuous-voltage mode > * Put more meat on the bones with regards to voltage-table mode > * Sort out formatting for ease of consumption > > Cc: devicetree@vger.kernel.org > Signed-off-by: Lee Jones <lee.jones@linaro.org> > --- > .../bindings/regulator/pwm-regulator.txt | 68 ++++++++++++++++++---- > 1 file changed, 56 insertions(+), 12 deletions(-) > > diff --git a/Documentation/devicetree/bindings/regulator/pwm-regulator.txt b/Documentation/devicetree/bindings/regulator/pwm-regulator.txt > index ce91f61..892b366 100644 > --- a/Documentation/devicetree/bindings/regulator/pwm-regulator.txt > +++ b/Documentation/devicetree/bindings/regulator/pwm-regulator.txt > @@ -1,27 +1,71 @@ > -pwm regulator bindings > +Bindings for the Generic PWM Regulator > +====================================== > + > +Currently supports 2 modes of operation: > + > +voltage-table: When in this mode, a voltage table (See below) of > + predefined voltage <=> duty-cycle values must be > + provided via DT. Limitations are that the regulator can > + only operate at the voltages supplied in the table. > + Intermediary duty-cycle values which would normally > + allow finer grained voltage selection are ignored and > + rendered useless. Although more control is given to > + the user if the assumptions made in continuous-voltage > + mode do not reign true. > + > +continuous-voltage: This mode uses the regulator's maximum and minimum > + supplied voltages specified in the > + regulator-{min,max}-microvolt properties to calculate > + appropriate duty-cycle values. This allows for a much > + more fine grained solution when compared with > + voltage-table mode above. This solution does make an > + assumption that a %50 duty-cycle value will cause the > + regulator voltage to run at half way between the > + supplied max_uV and min_uV values. Do we really have to specify a new property to select the mode ? The existing DT will have to be modified anyway, so maybe we can just add a new compatible string differentiate those two modes. Also note that if you're doing linear interpolation between the points specified in the voltage-table instead of doing it on the min -> max values, you wouldn't have to modify the binding. > > Required properties: > -- compatible: Should be "pwm-regulator" > -- pwms: OF device-tree PWM specification (see PWM binding pwm.txt) > -- voltage-table: voltage and duty table, include 2 members in each set of > - brackets, first one is voltage(unit: uv), the next is duty(unit: percent) > +-------------------- > +- compatible: Should be "pwm-regulator" > + > +- pwms: PWM specification (See: ../pwm/pwm.txt) > + > +One of these must be provided: > +- voltage-table: Voltage and Duty-Cycle table consisting of 2 cells > + First cell is voltage in microvolts (uV) > + Second cell is duty-cycle in percent (%) > + > +- max-duty-cycle: Maximum Duty-Cycle value -- this will normally be > + 255 (0xff) for an 8 bit PWM device Why are you introducing another random unit. What is max-duty-cycle really encoding (I guess it has to do with the precision you're expecting, but I'm not sure) ? The PWM framework is using nanoseconds, the existing pwm-regulator binding is using percents. Shouldn't we reuse one of them (I guess you changed that because the percent unit was not precise enough) ? Best Regards, Boris
diff --git a/Documentation/devicetree/bindings/regulator/pwm-regulator.txt b/Documentation/devicetree/bindings/regulator/pwm-regulator.txt index ce91f61..892b366 100644 --- a/Documentation/devicetree/bindings/regulator/pwm-regulator.txt +++ b/Documentation/devicetree/bindings/regulator/pwm-regulator.txt @@ -1,27 +1,71 @@ -pwm regulator bindings +Bindings for the Generic PWM Regulator +====================================== + +Currently supports 2 modes of operation: + +voltage-table: When in this mode, a voltage table (See below) of + predefined voltage <=> duty-cycle values must be + provided via DT. Limitations are that the regulator can + only operate at the voltages supplied in the table. + Intermediary duty-cycle values which would normally + allow finer grained voltage selection are ignored and + rendered useless. Although more control is given to + the user if the assumptions made in continuous-voltage + mode do not reign true. + +continuous-voltage: This mode uses the regulator's maximum and minimum + supplied voltages specified in the + regulator-{min,max}-microvolt properties to calculate + appropriate duty-cycle values. This allows for a much + more fine grained solution when compared with + voltage-table mode above. This solution does make an + assumption that a %50 duty-cycle value will cause the + regulator voltage to run at half way between the + supplied max_uV and min_uV values. Required properties: -- compatible: Should be "pwm-regulator" -- pwms: OF device-tree PWM specification (see PWM binding pwm.txt) -- voltage-table: voltage and duty table, include 2 members in each set of - brackets, first one is voltage(unit: uv), the next is duty(unit: percent) +-------------------- +- compatible: Should be "pwm-regulator" + +- pwms: PWM specification (See: ../pwm/pwm.txt) + +One of these must be provided: +- voltage-table: Voltage and Duty-Cycle table consisting of 2 cells + First cell is voltage in microvolts (uV) + Second cell is duty-cycle in percent (%) + +- max-duty-cycle: Maximum Duty-Cycle value -- this will normally be + 255 (0xff) for an 8 bit PWM device -Any property defined as part of the core regulator binding defined in -regulator.txt can also be used. +If both are provided, the current default is voltage-table mode. -Example: +Any property defined as part of the core regulator binding can also be used. +(See: ../regulator/regulator.txt) + +Continuous Voltage Example: pwm_regulator { compatible = "pwm-regulator; pwms = <&pwm1 0 8448 0>; + regulator-min-microvolt = <1016000>; + regulator-max-microvolt = <1114000>; + regulator-name = "vdd_logic"; + + max-duty-cycle = <255>; /* 8bit PWM */ + }; +Voltage Table Example: + pwm_regulator { + compatible = "pwm-regulator; + pwms = <&pwm1 0 8448 0>; + regulator-min-microvolt = <1016000>; + regulator-max-microvolt = <1114000>; + regulator-name = "vdd_logic"; + + /* Voltage Duty-Cycle */ voltage-table = <1114000 0>, <1095000 10>, <1076000 20>, <1056000 30>, <1036000 40>, <1016000 50>; - - regulator-min-microvolt = <1016000>; - regulator-max-microvolt = <1114000>; - regulator-name = "vdd_logic"; };
* Add support for continuous-voltage mode * Put more meat on the bones with regards to voltage-table mode * Sort out formatting for ease of consumption Cc: devicetree@vger.kernel.org Signed-off-by: Lee Jones <lee.jones@linaro.org> --- .../bindings/regulator/pwm-regulator.txt | 68 ++++++++++++++++++---- 1 file changed, 56 insertions(+), 12 deletions(-)