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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>
56 lines
2.1 KiB
Plaintext
56 lines
2.1 KiB
Plaintext
* Renesas R-Car USB 2.0 clock selector
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This file provides information on what the device node for the R-Car USB 2.0
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clock selector.
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If you connect an external clock to the USB_EXTAL pin only, you should set
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the clock rate to "usb_extal" node only.
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If you connect an oscillator to both the USB_XTAL and USB_EXTAL, this module
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is not needed because this is default setting. (Of course, you can set the
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clock rates to both "usb_extal" and "usb_xtal" nodes.
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Case 1: An external clock connects to R-Car SoC
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+----------+ +--- R-Car ---------------------+
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|External |---|USB_EXTAL ---> all usb channels|
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|clock | |USB_XTAL |
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+----------+ +-------------------------------+
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In this case, we need this driver with "usb_extal" clock.
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Case 2: An oscillator connects to R-Car SoC
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+----------+ +--- R-Car ---------------------+
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|Oscillator|---|USB_EXTAL -+-> all usb channels|
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| |---|USB_XTAL --+ |
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+----------+ +-------------------------------+
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In this case, we don't need this selector.
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Required properties:
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- compatible: "renesas,r8a7795-rcar-usb2-clock-sel" if the device is a part of
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an R8A7795 SoC.
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"renesas,r8a7796-rcar-usb2-clock-sel" if the device if a part of
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an R8A7796 SoC.
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"renesas,rcar-gen3-usb2-clock-sel" for a generic R-Car Gen3
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compatible device.
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When compatible with the generic version, nodes must list the
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SoC-specific version corresponding to the platform first
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followed by the generic version.
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- reg: offset and length of the USB 2.0 clock selector register block.
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- clocks: A list of phandles and specifier pairs.
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- clock-names: Name of the clocks.
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- The functional clock must be "ehci_ohci"
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- The USB_EXTAL clock pin must be "usb_extal"
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- The USB_XTAL clock pin must be "usb_xtal"
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- #clock-cells: Must be 0
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Example (R-Car H3):
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usb2_clksel: clock-controller@e6590630 {
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compatible = "renesas,r8a77950-rcar-usb2-clock-sel",
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"renesas,rcar-gen3-usb2-clock-sel";
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reg = <0 0xe6590630 0 0x02>;
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clocks = <&cpg CPG_MOD 703>, <&usb_extal>, <&usb_xtal>;
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clock-names = "ehci_ohci", "usb_extal", "usb_xtal";
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#clock-cells = <0>;
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};
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