| Message ID | 20220428110107.149524-1-marex@denx.de (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Headers | show |
| Series | [RESEND,v2,1/2] dt-bindings: clk: Introduce 'critical-clocks' property | expand |
On Thu, Apr 28, 2022 at 01:01:06PM +0200, Marek Vasut wrote: > Some platforms require select clock to be always running, e.g. because > those clock supply vital devices which are not otherwise attached to > the system and thus do not have a matching DT node and clock consumer. > > An example is a system where the SoC serves as a crystal oscillator > replacement for a programmable logic device. The "critical-clocks" > property of a clock controller allows listing clock which must never > be turned off. > > Clock listed in the "critical-clocks" property may have other consumers > in DT, listing the clock in "critical-clocks" only assures those clock > are never turned off, and none of these optional additional consumers > can turn the clock off either. > > The implementation is modeled after "protected-clocks". > > Signed-off-by: Marek Vasut <marex@denx.de> > Cc: Michael Turquette <mturquette@baylibre.com> > Cc: Rob Herring <robh+dt@kernel.org> > Cc: Stephen Boyd <sboyd@kernel.org> > Cc: devicetree@vger.kernel.org > To: linux-clk@vger.kernel.org > --- > V2: Update the commit message to clarify the behavior > --- > .../devicetree/bindings/clock/clock-bindings.txt | 16 ++++++++++++++++ > 1 file changed, 16 insertions(+) As mentioned on IRC, I'm okay with the property, but want Stephen's opinion on it. It also needs to be a schema in dtschema with the rest of the clock binding. I've submitted a patch to redirect this file to the schema. > > diff --git a/Documentation/devicetree/bindings/clock/clock-bindings.txt b/Documentation/devicetree/bindings/clock/clock-bindings.txt > index f2ea53832ac6..975230e603d1 100644 > --- a/Documentation/devicetree/bindings/clock/clock-bindings.txt > +++ b/Documentation/devicetree/bindings/clock/clock-bindings.txt > @@ -169,6 +169,22 @@ a shared clock is forbidden. > Configuration of common clocks, which affect multiple consumer devices can > be similarly specified in the clock provider node. > > +==Critical clocks== > + > +Some platforms require clock to be always running, e.g. because those clock require some clocks > +supply devices which are not otherwise attached to the system. One example > +is a system where the SoC serves as a crystal oscillator replacement for a > +programmable logic device. The critical-clocks property of a clock controller > +allows listing clock which must never be turned off. > + > + clock-controller@a000f000 { > + compatible = "vendor,clk95; > + reg = <0xa000f000 0x1000> > + #clocks-cells = <1>; > + ... > + critical-clocks = <UART3_CLK>, <SPI5_CLK>; > + }; > + > ==Protected clocks== > > Some platforms or firmwares may not fully expose all the clocks to the OS, such > -- > 2.35.1 > >
diff --git a/Documentation/devicetree/bindings/clock/clock-bindings.txt b/Documentation/devicetree/bindings/clock/clock-bindings.txt index f2ea53832ac6..975230e603d1 100644 --- a/Documentation/devicetree/bindings/clock/clock-bindings.txt +++ b/Documentation/devicetree/bindings/clock/clock-bindings.txt @@ -169,6 +169,22 @@ a shared clock is forbidden. Configuration of common clocks, which affect multiple consumer devices can be similarly specified in the clock provider node. +==Critical clocks== + +Some platforms require clock to be always running, e.g. because those clock +supply devices which are not otherwise attached to the system. One example +is a system where the SoC serves as a crystal oscillator replacement for a +programmable logic device. The critical-clocks property of a clock controller +allows listing clock which must never be turned off. + + clock-controller@a000f000 { + compatible = "vendor,clk95; + reg = <0xa000f000 0x1000> + #clocks-cells = <1>; + ... + critical-clocks = <UART3_CLK>, <SPI5_CLK>; + }; + ==Protected clocks== Some platforms or firmwares may not fully expose all the clocks to the OS, such
Some platforms require select clock to be always running, e.g. because those clock supply vital devices which are not otherwise attached to the system and thus do not have a matching DT node and clock consumer. An example is a system where the SoC serves as a crystal oscillator replacement for a programmable logic device. The "critical-clocks" property of a clock controller allows listing clock which must never be turned off. Clock listed in the "critical-clocks" property may have other consumers in DT, listing the clock in "critical-clocks" only assures those clock are never turned off, and none of these optional additional consumers can turn the clock off either. The implementation is modeled after "protected-clocks". Signed-off-by: Marek Vasut <marex@denx.de> Cc: Michael Turquette <mturquette@baylibre.com> Cc: Rob Herring <robh+dt@kernel.org> Cc: Stephen Boyd <sboyd@kernel.org> Cc: devicetree@vger.kernel.org To: linux-clk@vger.kernel.org --- V2: Update the commit message to clarify the behavior --- .../devicetree/bindings/clock/clock-bindings.txt | 16 ++++++++++++++++ 1 file changed, 16 insertions(+)