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clk: at91: add slow clk documentation
Add slow clk, and slow oscillators documentation.
Signed-off-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
Acked-by: Mike Turquette <mturquette@linaro.org>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
authored by
Boris BREZILLON
and committed by
Nicolas Ferre
4d735e54
80eded6c
+72
+72
Documentation/devicetree/bindings/clock/at91-clock.txt
+72
Documentation/devicetree/bindings/clock/at91-clock.txt
···
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Required properties:
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- compatible : shall be one of the following:
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"atmel,at91sam9x5-sckc":
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at91 SCKC (Slow Clock Controller)
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This node contains the slow clock definitions.
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"atmel,at91sam9x5-clk-slow-osc":
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at91 slow oscillator
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"atmel,at91sam9x5-clk-slow-rc-osc":
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at91 internal slow RC oscillator
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"atmel,at91rm9200-pmc" or
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"atmel,at91sam9g45-pmc" or
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"atmel,at91sam9n12-pmc" or
···
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at91 PMC (Power Management Controller)
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All at91 specific clocks (clocks defined below) must be child
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node of the PMC node.
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"atmel,at91sam9x5-clk-slow" (under sckc node)
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or
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"atmel,at91sam9260-clk-slow" (under pmc node):
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at91 slow clk
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"atmel,at91rm9200-clk-main-osc"
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"atmel,at91sam9x5-clk-main-rc-osc"
···
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"atmel,at91sam9x5-clk-utmi":
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at91 utmi clock
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Required properties for SCKC node:
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- reg : defines the IO memory reserved for the SCKC.
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- #size-cells : shall be 0 (reg is used to encode clk id).
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- #address-cells : shall be 1 (reg is used to encode clk id).
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For example:
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sckc: sckc@fffffe50 {
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compatible = "atmel,sama5d3-pmc";
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reg = <0xfffffe50 0x4>
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#size-cells = <0>;
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#address-cells = <1>;
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/* put at91 slow clocks here */
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};
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Required properties for internal slow RC oscillator:
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- #clock-cells : from common clock binding; shall be set to 0.
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- clock-frequency : define the internal RC oscillator frequency.
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Optional properties:
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- clock-accuracy : define the internal RC oscillator accuracy.
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For example:
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slow_rc_osc: slow_rc_osc {
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compatible = "atmel,at91sam9x5-clk-slow-rc-osc";
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clock-frequency = <32768>;
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clock-accuracy = <50000000>;
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};
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Required properties for slow oscillator:
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- #clock-cells : from common clock binding; shall be set to 0.
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- clocks : shall encode the main osc source clk sources (see atmel datasheet).
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Optional properties:
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- atmel,osc-bypass : boolean property. Set this when a clock signal is directly
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provided on XIN.
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For example:
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slow_osc: slow_osc {
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compatible = "atmel,at91rm9200-clk-slow-osc";
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#clock-cells = <0>;
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clocks = <&slow_xtal>;
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};
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Required properties for slow clock:
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- #clock-cells : from common clock binding; shall be set to 0.
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- clocks : shall encode the slow clk sources (see atmel datasheet).
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For example:
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clk32k: slck {
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compatible = "atmel,at91sam9x5-clk-slow";
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#clock-cells = <0>;
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clocks = <&slow_rc_osc &slow_osc>;
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};
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Required properties for PMC node:
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- reg : defines the IO memory reserved for the PMC.