On Tue, 27 Jan 2015, Mike Turquette wrote:
> Quoting Lee Jones (2015-01-26 03:14:00)
> > Signed-off-by: Lee Jones <lee.jones@xxxxxxxxxx>
> > ---
> > .../devicetree/bindings/clock/st/st,clk-domain.txt | 34 ++++++++++++++++++++++
> > 1 file changed, 34 insertions(+)
> > create mode 100644 Documentation/devicetree/bindings/clock/st/st,clk-domain.txt
> >
> > diff --git a/Documentation/devicetree/bindings/clock/st/st,clk-domain.txt b/Documentation/devicetree/bindings/clock/st/st,clk-domain.txt
> > new file mode 100644
> > index 0000000..7309937
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/clock/st/st,clk-domain.txt
> > @@ -0,0 +1,34 @@
> > +STMicroelectronics Clock Domain
> > +
> > +ST hardware have a bunch of clocks which must not be turned off.
> > +If drivers a) fail to obtain a reference to any of these or b) give
> > +up a previously obtained reference during suspend, the common clk
> > +framework will attempt to turn them off and the hardware will
> > +subsequently die. The only way to recover from this failure is to
> > +restart.
> > +
> > +To avoid either of these two scenarios from catastrophically
> > +disabling the running system we have implemented a clock domain
> > +where clocks are consumed and references are taken, thus preventing
> > +them from being shut down by the framework.
> > +
> > +We use the generic clock bindings found in:
> > + Documentation/devicetree/bindings/clock/clock-bindings.txt
> > +
> > +Required properties:
> > +- compatible : Must be "st,clk-domain"
>
> Seems like a useful feature for any clock provider, not just ST's. Have
> you thought about making this solution generic for DT-based clock
> providers?
>
> We could amend the common clock binding to include a special "always on"
> clock group that is automagically prepared and enabled when the clock
> provider/driver is registered, using a common function.
OMG, I'm actually going to strangle you!
This is what I've been proposing to you (privately) for weeks.
Does this ring any bells?
"Just FYI, I am not going to add any method to the kernel that
permanently enables a clock via some new api. At the worst case your
clock driver can simply call clk_prepare_enable in its probe
function (there are some examples of this)."
I will be more than happy to make this a generic driver, if thats what
you want (now). ;)
> > +Example:
> > +
> > +clk-domain {
> > + compatible = "st,clk-domain";
> > + clocks = <&clk_s_c0_flexgen CLK_EXT2F_A9>,
> > + <&clk_s_c0_flexgen CLK_COMPO_DVP>,
> > + <&clk_s_c0_flexgen CLK_MMC_1>,
> > + <&clk_s_c0_flexgen CLK_ICN_SBC>,
> > + <&clk_s_c0_flexgen CLK_ICN_LMI>,
> > + <&clk_s_c0_flexgen CLK_ICN_CPU>,
> > + <&clk_s_c0_flexgen CLK_TX_ICN_DMU>,
> > + <&clk_s_a0_flexgen CLK_IC_LMI0>,
> > + <&clk_m_a9>;
> > +};
--
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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