linux-arkmicro/linux/Documentation/devicetree/bindings/serial/amlogic,meson-uart.txt

Amlogic Meson SoC UART Serial Interface
=======================================

The Amlogic Meson SoC UART Serial Interface is present on a large range
of SoCs, and can be present either in the "Always-On" power domain or the
"Everything-Else" power domain.

The particularity of the "Always-On" Serial Interface is that the hardware
is active since power-on and does not need any clock gating and is usable
as very early serial console.

Required properties:
- compatible : compatible: value should be different for each SoC family as :
	- Meson6 : "amlogic,meson6-uart"
	- Meson8 : "amlogic,meson8-uart"
	- Meson8b : "amlogic,meson8b-uart"
	- GX (GXBB, GXL, GXM) : "amlogic,meson-gx-uart"
	eventually followed by : "amlogic,meson-ao-uart" if this UART interface
	is in the "Always-On" power domain.
- reg : offset and length of the register set for the device.
- interrupts : identifier to the device interrupt
- clocks : a list of phandle + clock-specifier pairs, one for each
	   entry in clock names.
- clock-names :
   * "xtal" for external xtal clock identifier
   * "pclk" for the bus core clock, either the clk81 clock or the gate clock
   * "baud" for the source of the baudrate generator, can be either the xtal
	or the pclk.

e.g.
uart_A: serial@84c0 {
	compatible = "amlogic,meson-gx-uart";
	reg = <0x0 0x84c0 0x0 0x14>;
	interrupts = <GIC_SPI 26 IRQ_TYPE_EDGE_RISING>;
	/* Use xtal as baud rate clock source */
	clocks = <&xtal>, <&clkc CLKID_UART0>, <&xtal>;
	clock-names = "xtal", "pclk", "baud";
};