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1478cebfa0
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 <mturquette@baylibre.com> Cc: linux-clk@vger.kernel.org Acked-by: Stephen Boyd <sboyd@codeaurora.org> Acked-by: Rob Herring <robh@kernel.org> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
41 lines
1.4 KiB
Plaintext
41 lines
1.4 KiB
Plaintext
ARM System Controller ICST clocks
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The ICS525 and ICS307 oscillators are produced by Integrated Devices
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Technology (IDT). ARM integrated these oscillators deeply into their
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reference designs by adding special control registers that manage such
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oscillators to their system controllers.
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The ARM system controller contains logic to serialize and initialize
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an ICST clock request after a write to the 32 bit register at an offset
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into the system controller. Furthermore, to even be able to alter one of
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these frequencies, the system controller must first be unlocked by
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writing a special token to another offset in the system controller.
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The ICST oscillator must be provided inside a system controller node.
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Required properties:
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- lock-offset: the offset address into the system controller where the
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unlocking register is located
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- vco-offset: the offset address into the system controller where the
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ICST control register is located (even 32 bit address)
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- compatible: must be one of "arm,syscon-icst525" or "arm,syscon-icst307"
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- #clock-cells: must be <0>
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- clocks: parent clock, since the ICST needs a parent clock to derive its
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frequency from, this attribute is compulsory.
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Example:
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syscon: syscon@10000000 {
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compatible = "syscon";
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reg = <0x10000000 0x1000>;
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oscclk0: osc0@0c {
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compatible = "arm,syscon-icst307";
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#clock-cells = <0>;
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lock-offset = <0x20>;
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vco-offset = <0x0c>;
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clocks = <&xtal24mhz>;
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};
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(...)
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};
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