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-clock property of a clock controller
allows listing clock which must never be turned off. The implementation here
is similar to "protected-clock".
Signed-off-by: Marek Vasut <marex@xxxxxxx>
Cc: Matti Vaittinen <matti.vaittinen@xxxxxxxxxxxxxxxxx>
Cc: Michael Turquette <mturquette@xxxxxxxxxxxx>
Cc: Rob Herring <robh+dt@xxxxxxxxxx>
Cc: Stephen Boyd <sboyd@xxxxxxxxxx>
Cc: devicetree@xxxxxxxxxxxxxxx
Cc: linux-power@xxxxxxxxxxxxxxxxx
To: linux-clk@xxxxxxxxxxxxxxx
---
.../devicetree/bindings/clock/clock-bindings.txt | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/Documentation/devicetree/bindings/clock/clock-bindings.txt b/Documentation/devicetree/bindings/clock/clock-bindings.txt
index f2ea53832ac63..d9a783c35c5a1 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-clock 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
--
2.34.1
