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?
[snip code]
--
Ben Dooks http://www.codethink.co.uk/
Senior Engineer Codethink - Providing Genius
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