3 This UART driver supports many chip variants and is used in mamy SoCs.
6 - compatible: "ns16550" or "nvidia,tegra20-uart"
7 - reg: start address and size of registers
8 - reg-shift: shift value indicating register size: 0=byte, 1=16bit,2=32bit etc.
9 - clock-frequency: input clock frequency for the UART (used to calculate the