Subversion Repositories shark

/*
 *  include/asm-i386/mach-pc9800/mach_time.h
 *
 *  Machine specific set RTC function for PC-9800.
 *  Written by Osamu Tomita <tomita@cinet.co.jp>
 */
#ifndef _MACH_TIME_H
#define _MACH_TIME_H

#include <linux/bcd.h>
#include <linux/upd4990a.h>

/* for check timing call set_rtc_mmss() */
/* used in arch/i386/time.c::do_timer_interrupt() */
/*
 * Because PC-9800's RTC (NEC uPD4990A) does not allow setting
 * time partially, we always have to read-modify-write the
 * entire time (including year) so that set_rtc_mmss() will
 * take quite much time to execute.  You may want to relax
 * RTC resetting interval (currently ~11 minuts)...
 */
#define USEC_AFTER      1000000
#define USEC_BEFORE     0

static inline int mach_set_rtc_mmss(unsigned long nowtime)
{
        int retval = 0;
        int real_seconds, real_minutes, cmos_minutes;
        struct upd4990a_raw_data data;

        upd4990a_get_time(&data, 1);
        cmos_minutes = BCD2BIN(data.min);

        /*
         * since we're only adjusting minutes and seconds,
         * don't interfere with hour overflow. This avoids
         * messing with unknown time zones but requires your
         * RTC not to be off by more than 15 minutes
         */
        real_seconds = nowtime % 60;
        real_minutes = nowtime / 60;
        if (((abs(real_minutes - cmos_minutes) + 15) / 30) & 1)
                real_minutes += 30;     /* correct for half hour time zone */
        real_minutes %= 60;

        if (abs(real_minutes - cmos_minutes) < 30) {
                u8 temp_seconds = (real_seconds / 10) * 16 + real_seconds % 10;
                u8 temp_minutes = (real_minutes / 10) * 16 + real_minutes % 10;

                if (data.sec != temp_seconds || data.min != temp_minutes) {
                        data.sec = temp_seconds;
                        data.min = temp_minutes;
                        upd4990a_set_time(&data, 1);
                }
        } else {
                printk(KERN_WARNING
                       "set_rtc_mmss: can't update from %d to %d\n",
                       cmos_minutes, real_minutes);
                retval = -1;
        }

        /* uPD4990A users' manual says we should issue Register Hold
         * command after reading time, or future Time Read command
         * may not work.  When we have set the time, this also starts
         * the clock.
         */
        upd4990a_serial_command(UPD4990A_REGISTER_HOLD);

        return retval;
}

static inline unsigned long mach_get_cmos_time(void)
{
        int i;
        u8 prev, cur;
        unsigned int year;
        struct upd4990a_raw_data data;

        /* Connect uPD4990A's DATA OUT pin to its 1Hz reference clock. */
        upd4990a_serial_command(UPD4990A_REGISTER_HOLD);

        /* Catch rising edge of reference clock.  */
        prev = ~UPD4990A_READ_DATA();
        for (i = 0; i < 1800000; i++) { /* may take up to 1 second... */
                __asm__ ("outb %%al,%0" : : "N" (0x5f)); /* 0.6usec delay */
                cur = UPD4990A_READ_DATA();
                if (!(prev & cur & 1))
                        break;
                prev = ~cur;
        }

        upd4990a_get_time(&data, 0);

        if ((year = BCD2BIN(data.year) + 1900) < 1995)
                year += 100;
        return mktime(year, data.mon, BCD2BIN(data.mday), BCD2BIN(data.hour),
                        BCD2BIN(data.min), BCD2BIN(data.sec));
}

#endif /* !_MACH_TIME_H */