On Tue, 28 Jul 2015, Rob Herring wrote:
> On Tue, Jul 28, 2015 at 9:39 AM, Lee Jones <lee.jones@xxxxxxxxxx> wrote:
> > On Tue, 28 Jul 2015, Rob Herring wrote:
> >
> >> On Mon, Jul 27, 2015 at 10:20 AM, Lee Jones <lee.jones@xxxxxxxxxx> wrote:
> >> > These OPPs are used in ST's CPUFreq implementation.
> >> >
> >> > Signed-off-by: Lee Jones <lee.jones@xxxxxxxxxx>
> >> > ---
> >> >
> >> > Changelog:
> >> > - None, new patch
> >> >
> >> > Documentation/devicetree/bindings/power/opp-st.txt | 76 ++++++++++++++++++++++
> >> > 1 file changed, 76 insertions(+)
> >> > create mode 100644 Documentation/devicetree/bindings/power/opp-st.txt
> >> >
> >> > diff --git a/Documentation/devicetree/bindings/power/opp-st.txt b/Documentation/devicetree/bindings/power/opp-st.txt
> >> > new file mode 100644
> >> > index 0000000..6eb2a91
> >> > --- /dev/null
> >> > +++ b/Documentation/devicetree/bindings/power/opp-st.txt
> >> > @@ -0,0 +1,76 @@
> >> > +STMicroelectronics OPP (Operating Performance Points) Bindings
> >> > +--------------------------------------------------------------
> >> > +
> >> > +Frequency Scaling only
> >> > +----------------------
> >> > +
> >> > +Located in CPU's node:
> >> > +
> >> > +- operating-points : [See: ./opp.txt]
> >> > +
> >> > +Example [safe]
> >> > +--------------
> >> > +
> >> > +cpus {
> >> > + cpu@0 {
> >> > + /* kHz uV */
> >> > + operating-points = <1500000 0
> >> > + 1200000 0
> >> > + 800000 0
> >> > + 500000 0>;
> >> > + };
> >> > +};
> >> > +
> >> > +Dynamic Voltage and Frequency Scaling (DVFS)
> >> > +--------------------------------------------
> >> > +
> >> > +Located in 'cpu0-opp-list' node [to be provided ONLY by the bootloader]:
> >> > +
> >> > +- compatible : Should be "operating-points-v2-sti"
> >> > +- opp{1..N} : Each 'oppX' subnode will contain the following properties:
> >> > + - opp-hz : CPU frequency [Hz] for this OPP [See: ./opp.txt]
> >> > + - st,avs : List of available voltages [uV] indexed by process code
> >>
> >> Add a unit suffix (-microvolt).
> >
> > Sure.
> >
> >> > + - st,cuts : Cut version this OPP is suitable for [0xFF means ALL]
> >> > + - st,substrate : Substrate version this OPP is suitable for [0xFF means ALL]
> >>
> >> How about not present means all?
> >
> > I think that would be an unsafe assumption. If it's forgotten, then
> > we may try to run an invalid/dangerous voltage/frequency combination.
> >
> > I'd really like 'all' to be defined an deliberate.
>
> Okay.
>
> >> > +- st,syscfg : Phandle to Major number register
> >> > + First cell: offset to major number
> >> > +- st,syscfg-eng : Phandle to Minor number and Pcode registers
> >> > + First cell: offset to process code
> >> > + Second cell: offset to minor number
> >>
> >> Would the proposed nvmem binding work for this?
> >
> > We already use sysconf for all of this type of stuff, as this
> > information is contained in ST's Sysconf banks. Moving over to a new
> > API would be a huge move and would require lots of planning
> > discussions with ST.
>
> Okay.
Thanks.
I'm going to fix up your suggestions above and add your Ack to make
Viresh happy. :)
Thanks Rob.
--
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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