On Mon, Mar 31, 2014 at 06:04:54PM +0100, Ben Dooks wrote: > 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. > > [snip] > > 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? Not setting a rate is supported by specifying the rate to 0. That should be documented of course. Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html