M48T86_MONTH
m48t86_writeb(dev, tm->tm_mon + 1, M48T86_MONTH);
m48t86_writeb(dev, bin2bcd(tm->tm_mon + 1), M48T86_MONTH);
tm->tm_mon = m48t86_readb(dev, M48T86_MONTH) - 1;
tm->tm_mon = bcd2bin(m48t86_readb(dev, M48T86_MONTH)) - 1;