xref: /freebsd/sys/contrib/device-tree/Bindings/clock/renesas,rcar-usb2-clock-sel.txt (revision cfd6422a5217410fbd66f7a7a8a64d9d85e61229) 
1* Renesas R-Car USB 2.0 clock selector
2
3This file provides information on what the device node for the R-Car USB 2.0
4clock selector.
5
6If you connect an external clock to the USB_EXTAL pin only, you should set
7the clock rate to "usb_extal" node only.
8If you connect an oscillator to both the USB_XTAL and USB_EXTAL, this module
9is not needed because this is default setting. (Of course, you can set the
10clock rates to both "usb_extal" and "usb_xtal" nodes.
11
12Case 1: An external clock connects to R-Car SoC
13	+----------+   +--- R-Car ---------------------+
14	|External  |---|USB_EXTAL ---> all usb channels|
15	|clock     |   |USB_XTAL                       |
16	+----------+   +-------------------------------+
17In this case, we need this driver with "usb_extal" clock.
18
19Case 2: An oscillator connects to R-Car SoC
20	+----------+   +--- R-Car ---------------------+
21	|Oscillator|---|USB_EXTAL -+-> all usb channels|
22	|          |---|USB_XTAL --+                   |
23	+----------+   +-------------------------------+
24In this case, we don't need this selector.
25
26Required properties:
27- compatible: "renesas,r8a7795-rcar-usb2-clock-sel" if the device is a part of
28	      an R8A7795 SoC.
29	      "renesas,r8a7796-rcar-usb2-clock-sel" if the device if a part of
30	      an R8A77960 SoC.
31	      "renesas,r8a77961-rcar-usb2-clock-sel" if the device if a part of
32	      an R8A77961 SoC.
33	      "renesas,rcar-gen3-usb2-clock-sel" for a generic R-Car Gen3
34	      compatible device.
35
36	      When compatible with the generic version, nodes must list the
37	      SoC-specific version corresponding to the platform first
38	      followed by the generic version.
39
40- reg: offset and length of the USB 2.0 clock selector register block.
41- clocks: A list of phandles and specifier pairs.
42- clock-names: Name of the clocks.
43 - The functional clock of USB 2.0 host side must be "ehci_ohci"
44 - The functional clock of HS-USB side must be "hs-usb-if"
45 - The USB_EXTAL clock pin must be "usb_extal"
46 - The USB_XTAL clock pin must be "usb_xtal"
47- #clock-cells: Must be 0
48- power-domains: A phandle and symbolic PM domain specifier.
49                 See power/renesas,rcar-sysc.yaml.
50- resets: A list of phandles and specifier pairs.
51- reset-names: Name of the resets.
52 - The reset of USB 2.0 host side must be "ehci_ohci"
53 - The reset of HS-USB side must be "hs-usb-if"
54
55Example (R-Car H3):
56
57	usb2_clksel: clock-controller@e6590630 {
58		compatible = "renesas,r8a7795-rcar-usb2-clock-sel",
59			     "renesas,rcar-gen3-usb2-clock-sel";
60		reg = <0 0xe6590630 0 0x02>;
61		clocks = <&cpg CPG_MOD 703>, <&cpg CPG_MOD 704>,
62			 <&usb_extal>, <&usb_xtal>;
63		clock-names = "ehci_ohci", "hs-usb-if", "usb_extal", "usb_xtal";
64		#clock-cells = <0>;
65		power-domains = <&sysc R8A7795_PD_ALWAYS_ON>;
66		resets = <&cpg 703>, <&cpg 704>;
67		reset-names = "ehci_ohci", "hs-usb-if";
68	};
69