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authorYoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>2017-07-25 15:26:27 +0900
committerGeert Uytterhoeven <geert+renesas@glider.be>2017-08-17 09:22:23 +0200
commit311accb64570db45604dd8929af6f7da735835c9 (patch)
tree487638eae7cc90b411539b6f723354335cd08a10 /Documentation
parentd71e851d82c6cfe58bc592ce1e59e924f0374d0f (diff)
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clk: renesas: rcar-usb2-clock-sel: Add R-Car USB 2.0 clock selector PHY
R-Car USB 2.0 controller can change the clock source from an oscillator to an external clock via a register. So, this patch adds support the clock source selector as a clock driver. Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com> Acked-by: Rob Herring <robh@kernel.org> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/devicetree/bindings/clock/renesas,rcar-usb2-clock-sel.txt55
1 files changed, 55 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/clock/renesas,rcar-usb2-clock-sel.txt b/Documentation/devicetree/bindings/clock/renesas,rcar-usb2-clock-sel.txt
new file mode 100644
index 000000000000..e96e085271c1
--- /dev/null
+++ b/Documentation/devicetree/bindings/clock/renesas,rcar-usb2-clock-sel.txt
@@ -0,0 +1,55 @@
+* Renesas R-Car USB 2.0 clock selector
+
+This file provides information on what the device node for the R-Car USB 2.0
+clock selector.
+
+If you connect an external clock to the USB_EXTAL pin only, you should set
+the clock rate to "usb_extal" node only.
+If you connect an oscillator to both the USB_XTAL and USB_EXTAL, this module
+is not needed because this is default setting. (Of course, you can set the
+clock rates to both "usb_extal" and "usb_xtal" nodes.
+
+Case 1: An external clock connects to R-Car SoC
+ +----------+ +--- R-Car ---------------------+
+ |External |---|USB_EXTAL ---> all usb channels|
+ |clock | |USB_XTAL |
+ +----------+ +-------------------------------+
+In this case, we need this driver with "usb_extal" clock.
+
+Case 2: An oscillator connects to R-Car SoC
+ +----------+ +--- R-Car ---------------------+
+ |Oscillator|---|USB_EXTAL -+-> all usb channels|
+ | |---|USB_XTAL --+ |
+ +----------+ +-------------------------------+
+In this case, we don't need this selector.
+
+Required properties:
+- compatible: "renesas,r8a7795-rcar-usb2-clock-sel" if the device is a part of
+ an R8A7795 SoC.
+ "renesas,r8a7796-rcar-usb2-clock-sel" if the device if a part of
+ an R8A7796 SoC.
+ "renesas,rcar-gen3-usb2-clock-sel" for a generic R-Car Gen3
+ compatible device.
+
+ When compatible with the generic version, nodes must list the
+ SoC-specific version corresponding to the platform first
+ followed by the generic version.
+
+- reg: offset and length of the USB 2.0 clock selector register block.
+- clocks: A list of phandles and specifier pairs.
+- clock-names: Name of the clocks.
+ - The functional clock must be "ehci_ohci"
+ - The USB_EXTAL clock pin must be "usb_extal"
+ - The USB_XTAL clock pin must be "usb_xtal"
+- #clock-cells: Must be 0
+
+Example (R-Car H3):
+
+ usb2_clksel: clock-controller@e6590630 {
+ compatible = "renesas,r8a77950-rcar-usb2-clock-sel",
+ "renesas,rcar-gen3-usb2-clock-sel";
+ reg = <0 0xe6590630 0 0x02>;
+ clocks = <&cpg CPG_MOD 703>, <&usb_extal>, <&usb_xtal>;
+ clock-names = "ehci_ohci", "usb_extal", "usb_xtal";
+ #clock-cells = <0>;
+ };