EPSON RTC-8583 support code on i2c bus

[yamori813_yahoo.co.jp]

Summary

This is start up log.

https://gist.github.com/yamori813/bd6ccdbd73dd02eebfdd0bd6d92411d8

Test Plan

on RT2880 (Planex_MZK-W300NAG)

[yamori813_yahoo.co.jp]

This is dts

&i2c {
        status = "okay";
        rtc8583 {
                status = "okay";
                compatible = "epson,rtc8583";
                reg = <0x50>;
        };
};

[mizhka]

Few cosmetic style issues...

sys/dev/iicbus/rtc8583.c

183–200

I see datasheet for this clock, but can't understand this algo :)
ftp://download.epson-europe.com/pub/electronics-de/quartz/rtc8583.pdf

is 0x10 register number mentioned in datasheet? Does it mean that year is stored in user S-RAM and don't describe in datasheet?

[yamori813_yahoo.co.jp]

• use err value at return