xref: /freebsd/sys/contrib/device-tree/Bindings/rtc/rtc-meson-vrtc.txt (revision 02e9120893770924227138ba49df1edb3896112a)
1* Amlogic Virtual RTC (VRTC)
2
3This is a Linux interface to an RTC managed by firmware, hence it's
4virtual from a Linux perspective.  The interface is 1 register where
5an alarm time (in seconds) is to be written.
6
7Required properties:
8- compatible: should be "amlogic,meson-vrtc"
9- reg: physical address for the alarm register
10
11The alarm register is a simple scratch register shared between the
12application processors (AP) and the secure co-processor (SCP.)  When
13the AP suspends, the SCP will use the value of this register to
14program an always-on timer before going sleep. When the timer expires,
15the SCP will wake up and will then wake the AP.
16
17Example:
18
19	vrtc: rtc@0a8 {
20		compatible = "amlogic,meson-vrtc";
21		reg = <0x0 0x000a8 0x0 0x4>;
22	};
23