xref: /linux/Documentation/devicetree/bindings/rtc/rtc-cmos.txt (revision 1573c26775f2e7ce7dfd6015b46f2cf55fa87368)
1 Motorola mc146818 compatible RTC
2~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
3
4Required properties:
5  - compatible : "motorola,mc146818"
6  - reg : should contain registers location and length.
7
8Optional properties:
9  - interrupts : should contain interrupt.
10  - ctrl-reg : Contains the initial value of the control register also
11    called "Register B".
12  - freq-reg : Contains the initial value of the frequency register also
13    called "Register A".
14
15"Register A" and "B" are usually initialized by the firmware (BIOS for
16instance). If this is not done, it can be performed by the driver.
17
18ISA Example:
19
20	rtc@70 {
21	         compatible = "motorola,mc146818";
22	         interrupts = <8 3>;
23	         interrupt-parent = <&ioapic1>;
24	         ctrl-reg = <2>;
25	         freq-reg = <0x26>;
26	         reg = <1 0x70 2>;
27	 };
28