RSECCNT
unsigned char buf[] = { RSECCNT, RMINCNT, RHRCNT,
ret = ret ? ret : write_reg(dev, RSECCNT, bin2bcd(dt->tm_sec));
tm->tm_sec = bcd2bin(readb(rtc->regbase + RSECCNT));
writeb(bin2bcd(tm->tm_sec), rtc->regbase + RSECCNT);