xref: /freebsd-src/sys/contrib/device-tree/Bindings/rtc/rtc-cmos.txt (revision aa1a8ff2d6dbc51ef058f46f3db5a8bb77967145)
1c66ec88fSEmmanuel Vadot Motorola mc146818 compatible RTC
2c66ec88fSEmmanuel Vadot~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
3c66ec88fSEmmanuel Vadot
4c66ec88fSEmmanuel VadotRequired properties:
5c66ec88fSEmmanuel Vadot  - compatible : "motorola,mc146818"
6c66ec88fSEmmanuel Vadot  - reg : should contain registers location and length.
7c66ec88fSEmmanuel Vadot
8c66ec88fSEmmanuel VadotOptional properties:
9c66ec88fSEmmanuel Vadot  - interrupts : should contain interrupt.
10c66ec88fSEmmanuel Vadot  - ctrl-reg : Contains the initial value of the control register also
11c66ec88fSEmmanuel Vadot    called "Register B".
12c66ec88fSEmmanuel Vadot  - freq-reg : Contains the initial value of the frequency register also
13*aa1a8ff2SEmmanuel Vadot    called "Register A".
14c66ec88fSEmmanuel Vadot
15c66ec88fSEmmanuel Vadot"Register A" and "B" are usually initialized by the firmware (BIOS for
16c66ec88fSEmmanuel Vadotinstance). If this is not done, it can be performed by the driver.
17c66ec88fSEmmanuel Vadot
18c66ec88fSEmmanuel VadotISA Example:
19c66ec88fSEmmanuel Vadot
20c66ec88fSEmmanuel Vadot	rtc@70 {
21c66ec88fSEmmanuel Vadot	         compatible = "motorola,mc146818";
22c66ec88fSEmmanuel Vadot	         interrupts = <8 3>;
23c66ec88fSEmmanuel Vadot	         interrupt-parent = <&ioapic1>;
24c66ec88fSEmmanuel Vadot	         ctrl-reg = <2>;
25c66ec88fSEmmanuel Vadot	         freq-reg = <0x26>;
26c66ec88fSEmmanuel Vadot	         reg = <1 0x70 2>;
27c66ec88fSEmmanuel Vadot	 };
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