- 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>;
};
