18c2ecf20Sopenharmony_ci Motorola mc146818 compatible RTC 28c2ecf20Sopenharmony_ci~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 38c2ecf20Sopenharmony_ci 48c2ecf20Sopenharmony_ciRequired properties: 58c2ecf20Sopenharmony_ci - compatible : "motorola,mc146818" 68c2ecf20Sopenharmony_ci - reg : should contain registers location and length. 78c2ecf20Sopenharmony_ci 88c2ecf20Sopenharmony_ciOptional properties: 98c2ecf20Sopenharmony_ci - interrupts : should contain interrupt. 108c2ecf20Sopenharmony_ci - ctrl-reg : Contains the initial value of the control register also 118c2ecf20Sopenharmony_ci called "Register B". 128c2ecf20Sopenharmony_ci - freq-reg : Contains the initial value of the frequency register also 138c2ecf20Sopenharmony_ci called "Regsiter A". 148c2ecf20Sopenharmony_ci 158c2ecf20Sopenharmony_ci"Register A" and "B" are usually initialized by the firmware (BIOS for 168c2ecf20Sopenharmony_ciinstance). If this is not done, it can be performed by the driver. 178c2ecf20Sopenharmony_ci 188c2ecf20Sopenharmony_ciISA Example: 198c2ecf20Sopenharmony_ci 208c2ecf20Sopenharmony_ci rtc@70 { 218c2ecf20Sopenharmony_ci compatible = "motorola,mc146818"; 228c2ecf20Sopenharmony_ci interrupts = <8 3>; 238c2ecf20Sopenharmony_ci interrupt-parent = <&ioapic1>; 248c2ecf20Sopenharmony_ci ctrl-reg = <2>; 258c2ecf20Sopenharmony_ci freq-reg = <0x26>; 268c2ecf20Sopenharmony_ci reg = <1 0x70 2>; 278c2ecf20Sopenharmony_ci }; 28