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Diffstat (limited to 'Documentation/devicetree/bindings/clock/renesas,rcar-usb2-clock-sel.txt')
-rw-r--r-- | Documentation/devicetree/bindings/clock/renesas,rcar-usb2-clock-sel.txt | 68 |
1 files changed, 68 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 000000000..da92f5748 --- /dev/null +++ b/Documentation/devicetree/bindings/clock/renesas,rcar-usb2-clock-sel.txt @@ -0,0 +1,68 @@ +* 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 R8A77960 SoC. + "renesas,r8a77961-rcar-usb2-clock-sel" if the device if a part of + an R8A77961 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 of USB 2.0 host side must be "ehci_ohci" + - The functional clock of HS-USB side must be "hs-usb-if" + - The USB_EXTAL clock pin must be "usb_extal" + - The USB_XTAL clock pin must be "usb_xtal" +- #clock-cells: Must be 0 +- power-domains: A phandle and symbolic PM domain specifier. + See power/renesas,rcar-sysc.yaml. +- resets: A list of phandles and specifier pairs. +- reset-names: Name of the resets. + - The reset of USB 2.0 host side must be "ehci_ohci" + - The reset of HS-USB side must be "hs-usb-if" + +Example (R-Car H3): + + usb2_clksel: clock-controller@e6590630 { + compatible = "renesas,r8a7795-rcar-usb2-clock-sel", + "renesas,rcar-gen3-usb2-clock-sel"; + reg = <0 0xe6590630 0 0x02>; + clocks = <&cpg CPG_MOD 703>, <&cpg CPG_MOD 704>, + <&usb_extal>, <&usb_xtal>; + clock-names = "ehci_ohci", "hs-usb-if", "usb_extal", "usb_xtal"; + #clock-cells = <0>; + power-domains = <&sysc R8A7795_PD_ALWAYS_ON>; + resets = <&cpg 703>, <&cpg 704>; + reset-names = "ehci_ohci", "hs-usb-if"; + }; |