Messages in this thread | | | Date | Mon, 31 Mar 2014 18:04:54 +0100 | From | Ben Dooks <> | Subject | Re: [PATCH RFC v4 2/2] clk: Add handling of clk parent and rate assigned from DT |
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On 31/03/14 17:41, Sylwester Nawrocki wrote: > This function adds a helper function to configure clock parents and rates > as specified in clock-parents, clock-rates DT properties for a consumer > device and a call to it before driver is bound to a device.
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tree/bindings/clock/clock-bindings.txt b/Documentation/devicetree/bindings/clock/clock-bindings.txt > index 700e7aa..59fbb4e 100644 > --- a/Documentation/devicetree/bindings/clock/clock-bindings.txt > +++ b/Documentation/devicetree/bindings/clock/clock-bindings.txt > @@ -132,3 +132,45 @@ clock signal, and a UART. > ("pll" and "pll-switched"). > * The UART has its baud clock connected the external oscillator and its > register clock connected to the PLL clock (the "pll-switched" signal) > + > +==Assigned clock parents and rates== > + > +Some platforms require static initial configuration of parts of the clocks > +controller. Such a configuration can be specified in a clock consumer node > +through clock-parents and clock-rates DT properties. The former should > +contain a list of parent clocks in form of phandle and clock specifier pairs, > +the latter the list of assigned clock frequency values (one cell each). > + > + uart@a000 { > + compatible = "fsl,imx-uart"; > + reg = <0xa000 0x1000>; > + ... > + clocks = <&clkcon 0>, <&clkcon 3>; > + clock-names = "baud", "mux"; > + > + clock-parents = <0>, <&pll 1>; > + clock-rates = <460800>; > + }; > + > +In this example the pll is set as parent of "mux" clock and frequency of "baud" > +clock is specified as 460800 Hz. > + > +Configuring a clock parent and rate through the device node that uses > +the clock can be done only for clocks that have a single user. Specifying > +conflicting parent or rate configuration in multiple consumer nodes for > +a shared clock is forbidden. > + > +Configuration of common clocks, which affect multiple consumer devices > +can be specified in a dedicated 'assigned-clocks' subnode of a clock > +provider node, e.g.: > + > + clkcon { > + ... > + #clock-cells = <1>; > + > + assigned-clocks { > + clocks = <&clkcon 16>, <&clkcon 17>; > + clock-parents = <0>, <&clkcon 1>; > + clock-rates = <200000>; > + }; > + };
How do you support not-setting a rate for a clock?
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-- Ben Dooks http://www.codethink.co.uk/ Senior Engineer Codethink - Providing Genius
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