From 1478cebfa0b472f797134d6a1d6d7e1222fd1a96 Mon Sep 17 00:00:00 2001 From: Linus Walleij Date: Tue, 13 Oct 2015 14:27:30 +0200 Subject: [PATCH] clk: add ARM syscon ICST device tree bindings This adds the device tree bindings for the ARM Syscon ICST oscillators, which is a register-level interface to the Integrated Device Technology (IDT) ICS525 and ICS307 serially programmable oscillators. Cc: devicetree@vger.kernel.org Cc: Michael Turquette Cc: linux-clk@vger.kernel.org Acked-by: Stephen Boyd Acked-by: Rob Herring Signed-off-by: Linus Walleij --- .../bindings/clock/arm-syscon-icst.txt | 40 +++++++++++++++++++ 1 file changed, 40 insertions(+) create mode 100644 Documentation/devicetree/bindings/clock/arm-syscon-icst.txt 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..8b7177cecb36 --- /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 serialize and initialize +an ICST clock request after a write to the 32 bit register at an offset +into the system controller. Furthermore, to even be able to alter one of +these frequencies, the system controller must first be unlocked by +writing a special token to another offset in the system controller. + +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) +- 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@10000000 { + compatible = "syscon"; + reg = <0x10000000 0x1000>; + + oscclk0: osc0@0c { + compatible = "arm,syscon-icst307"; + #clock-cells = <0>; + lock-offset = <0x20>; + vco-offset = <0x0c>; + clocks = <&xtal24mhz>; + }; + (...) +}; -- 2.20.1