int atari_tt_hwclk()

in atari/time.c [199:319]

• 93 lines of code
• 21 McCabe index (conditional complexity)

int atari_tt_hwclk( int op, struct rtc_time *t )
{
    int sec=0, min=0, hour=0, day=0, mon=0, year=0, wday=0;
    unsigned long	flags;
    unsigned char	ctrl;
    int pm = 0;

    ctrl = RTC_READ(RTC_CONTROL); /* control registers are
                                   * independent from the UIP */

    if (op) {
        /* write: prepare values */

        sec  = t->tm_sec;
        min  = t->tm_min;
        hour = t->tm_hour;
        day  = t->tm_mday;
        mon  = t->tm_mon + 1;
        year = t->tm_year - atari_rtc_year_offset;
        wday = t->tm_wday + (t->tm_wday >= 0);

        if (!(ctrl & RTC_24H)) {
	    if (hour > 11) {
		pm = 0x80;
		if (hour != 12)
		    hour -= 12;
	    }
	    else if (hour == 0)
		hour = 12;
        }

        if (!(ctrl & RTC_DM_BINARY)) {
	    sec = bin2bcd(sec);
	    min = bin2bcd(min);
	    hour = bin2bcd(hour);
	    day = bin2bcd(day);
	    mon = bin2bcd(mon);
	    year = bin2bcd(year);
	    if (wday >= 0)
		wday = bin2bcd(wday);
        }
    }

    /* Reading/writing the clock registers is a bit critical due to
     * the regular update cycle of the RTC. While an update is in
     * progress, registers 0..9 shouldn't be touched.
     * The problem is solved like that: If an update is currently in
     * progress (the UIP bit is set), the process sleeps for a while
     * (50ms). This really should be enough, since the update cycle
     * normally needs 2 ms.
     * If the UIP bit reads as 0, we have at least 244 usecs until the
     * update starts. This should be enough... But to be sure,
     * additionally the RTC_SET bit is set to prevent an update cycle.
     */

    while( RTC_READ(RTC_FREQ_SELECT) & RTC_UIP ) {
	if (in_atomic() || irqs_disabled())
	    mdelay(1);
	else
	    schedule_timeout_interruptible(HWCLK_POLL_INTERVAL);
    }

    local_irq_save(flags);
    RTC_WRITE( RTC_CONTROL, ctrl | RTC_SET );
    if (!op) {
        sec  = RTC_READ( RTC_SECONDS );
        min  = RTC_READ( RTC_MINUTES );
        hour = RTC_READ( RTC_HOURS );
        day  = RTC_READ( RTC_DAY_OF_MONTH );
        mon  = RTC_READ( RTC_MONTH );
        year = RTC_READ( RTC_YEAR );
        wday = RTC_READ( RTC_DAY_OF_WEEK );
    }
    else {
        RTC_WRITE( RTC_SECONDS, sec );
        RTC_WRITE( RTC_MINUTES, min );
        RTC_WRITE( RTC_HOURS, hour + pm);
        RTC_WRITE( RTC_DAY_OF_MONTH, day );
        RTC_WRITE( RTC_MONTH, mon );
        RTC_WRITE( RTC_YEAR, year );
        if (wday >= 0) RTC_WRITE( RTC_DAY_OF_WEEK, wday );
    }
    RTC_WRITE( RTC_CONTROL, ctrl & ~RTC_SET );
    local_irq_restore(flags);

    if (!op) {
        /* read: adjust values */

        if (hour & 0x80) {
	    hour &= ~0x80;
	    pm = 1;
	}

	if (!(ctrl & RTC_DM_BINARY)) {
	    sec = bcd2bin(sec);
	    min = bcd2bin(min);
	    hour = bcd2bin(hour);
	    day = bcd2bin(day);
	    mon = bcd2bin(mon);
	    year = bcd2bin(year);
	    wday = bcd2bin(wday);
        }

        if (!(ctrl & RTC_24H)) {
	    if (!pm && hour == 12)
		hour = 0;
	    else if (pm && hour != 12)
		hour += 12;
        }

        t->tm_sec  = sec;
        t->tm_min  = min;
        t->tm_hour = hour;
        t->tm_mday = day;
        t->tm_mon  = mon - 1;
        t->tm_year = year + atari_rtc_year_offset;
        t->tm_wday = wday - 1;
    }

    return( 0 );
}