[PATCH 08/13] clk: add ARM syscon ICST device tree bindings
From: Stephen Boyd <hidden>
Date: 2015-10-15 19:23:25
Also in:
linux-clk, linux-devicetree
On 10/15, Linus Walleij wrote:
quoted hunk ↗ jump to hunk
diff --git a/Documentation/devicetree/bindings/clock/arm-syscon-icst.txt b/Documentation/devicetree/bindings/clock/arm-syscon-icst.txt new file mode 100644 index 000000000000..19eb3aa765c7 --- /dev/null +++ b/Documentation/devicetree/bindings/clock/arm-syscon-icst.txt@@ -0,0 +1,40 @@ +ARM System Controller ICST clocks + +The ICS525 and ICS307 oscillators are produced by Integrated Devices +Technology (IDT). ARM integrated these oscillators deeply into their +reference designs by adding special control registers that manage such +oscillators to their system controllers. + +The ARM system controller contains logic to serialized and initialize
serialize ?
+an ICST clock request after a write to the 32 bit register at an offset +into the system controller. Further, to even be able to alter one of
Furthermore?
+these frequencies, the system controller must first be unlocked by +writing a special token to another offset in the system controller.
Sounds like a great design!
+ +The ICST oscillator must be provided inside a system controller node. + +Required properties: +- lock-offset: the offset address into the system controller where the + unlocking register is located +- vco-offset: the offset address into the system controller where the + ICST control register is located (even 32 bit address)
Is there any reason why we don't use a reg property for this?
+- compatible: must be one of "arm,syscon-icst525" or "arm,syscon-icst307"
+- #clock-cells: must be <0>
+- clocks: parent clock, since the ICST needs a parent clock to derive its
+ frequency from, this attribute is compulsory.
+
+Example:
+
+syscon: syscon at 10000000 {
+ compatible = "syscon";
+ reg = <0x10000000 0x1000>;
+
+ oscclk0: osc0 at 0c {
+ compatible = "arm,syscon-icst307";
+ #clock-cells = <0>;
+ lock-offset = <0x20>;
+ vco-offset = <0x0C>;lowercase the C?
+ clocks = <&xtal24mhz>; + }; + (...) +};
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