[PATCH 2/2] clk: clps711x: Add DT bindings documentation

Mark Rutland
2014-06-02T10:42:22Z

On Mon, Jun 02, 2014 at 10:32:48AM +0100, Alexander Shiyan wrote:
> Mon, 2 Jun 2014 09:56:51 +0100 ?? Mark Rutland <mark.rutland@arm.com>:
> > On Sun, Jun 01, 2014 at 10:55:22AM +0100, Alexander Shiyan wrote:
> > > This patch adds DT binding documentation for the Cirrus Logic
> > > CLPS711X-based CPUs clock subsystem.
> > >
> > > Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
> > > ---
> > > .../devicetree/bindings/clock/clps711x-clock.txt | 19 +++++++++++++++++++
> > > 1 file changed, 19 insertions(+)
> > > create mode 100644 Documentation/devicetree/bindings/clock/clps711x-clock.txt
> > >
> > > diff --git a/Documentation/devicetree/bindings/clock/clps711x-clock.txt b/Documentation/devicetree/bindings/clock/clps711x-clock.txt
> > > new file mode 100644
> > > index 0000000..0fdf3c9
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/clock/clps711x-clock.txt
> > > @@ -0,0 +1,19 @@
> > > +* Clock bindings for the Cirrus Logic CLPS711X CPUs
> > > +
> > > +Required properties:
> > > +- compatible : Shall contain "cirrus,clps711x-clk".
> > > +- reg : Address of the internal register set.
> > > +- cpufreq : Factory set default frequency in HZ.
> >
> > Huh? Why is this called "cpufreq" what is this the frequency of,
> > exactly?
> >
> > Is this an input or an output?
>
> Modern CLPS711X CPUs support PLL reprogramming, while for older processors,
> this procedure is not possible and the CPU clock is set to a fixed value. Thus if the
> value of the PLL multiplier is not correct (missing), we use a fixed CPU frequency
> of the processor, described in DT, which allows us to use the driver for the new and
> old versions of this CPU.

Ok. So this is the frequency of a (non-programmable) PLL which feeds the
clock IP block?

Or is this internal to the IP block?

Typically we'd use "clock-frequency" as the name for such an input, or
just model it as a normal clock input and feed it a fixed-rate-clock for
the non-programmable case.

Cheers,
Mark.