base/arch/x86_64/hal/rtc.c

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/*
 * Copyright (C) 2005-2008  Paolo Mantegazza  (mantegazza@aero.polimi.it)
 * (RTC specific part with) Giuseppe Quaranta (quaranta@aero.polimi.it)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */


#ifdef INCLUDED_BY_HAL_C

#include <linux/mc146818rtc.h>
static inline unsigned char RT_CMOS_READ(unsigned char addr)
{
    outb_p(addr, RTC_PORT(0));
    return inb_p(RTC_PORT(1));
}

//#define TEST_RTC
#define MIN_RTC_FREQ  2
#define MAX_RTC_FREQ  8192
#define RTC_FREQ      MAX_RTC_FREQ

static void rt_broadcast_rtc_interrupt(void)
{
#ifdef CONFIG_SMP
    apic_wait_icr_idle();
    apic_write_around(APIC_ICR, APIC_DM_FIXED | APIC_DEST_ALLBUT | RTAI_APIC_TIMER_VECTOR | APIC_DEST_LOGICAL);
    ((void (*)(void))rtai_realtime_irq[RTAI_APIC_TIMER_IPI].handler)();
#endif
}

static void (*usr_rtc_handler)(void);

static void rtc_handler(int irq, int rtc_freq)
{
#ifdef TEST_RTC
    static int stp, cnt;
    if (++cnt == rtc_freq) {
        rt_printk("<> IRQ %d, %d: CNT %d <>\n", irq, ++stp, cnt);
        cnt = 0;
    }
#endif
    RT_CMOS_READ(RTC_INTR_FLAGS); // CMOS_READ(RTC_INTR_FLAGS);
    rt_enable_irq(RTC_IRQ);
    if (usr_rtc_handler) {
        usr_rtc_handler();
    }
}

void rt_request_rtc(long rtc_freq, void *handler)
{
    int pwr2;

    if (rtc_freq <= 0) {
        rtc_freq = RTC_FREQ;
    }
    if (rtc_freq > MAX_RTC_FREQ) {
        rtc_freq = MAX_RTC_FREQ;
    } else if (rtc_freq < MIN_RTC_FREQ) {
        rtc_freq = MIN_RTC_FREQ;
    }
    pwr2 = 1;
    if (rtc_freq > MIN_RTC_FREQ) {
        while (rtc_freq > (1 << pwr2)) {
            pwr2++;
        }
        if (rtc_freq <= ((3*(1 << (pwr2 - 1)) + 1)>>1)) {
            pwr2--;
        }
    }

    rt_disable_irq(RTC_IRQ);
    rt_release_irq(RTC_IRQ);
    rtai_cli();
    CMOS_WRITE(CMOS_READ(RTC_FREQ_SELECT), RTC_FREQ_SELECT);
    CMOS_WRITE(CMOS_READ(RTC_CONTROL),     RTC_CONTROL);
    CMOS_WRITE(RTC_REF_CLCK_32KHZ | (16 - pwr2),          RTC_FREQ_SELECT);
    CMOS_WRITE((CMOS_READ(RTC_CONTROL) & 0x8F) | RTC_PIE, RTC_CONTROL);
    rtai_sti();
    usr_rtc_handler = handler ? handler : rt_broadcast_rtc_interrupt;
    rt_request_irq(RTC_IRQ, (void *)rtc_handler, (void *)rtc_freq, 0);
    rt_enable_irq(RTC_IRQ);
    CMOS_READ(RTC_INTR_FLAGS);
    return;
}

void rt_release_rtc(void)
{
    rt_disable_irq(RTC_IRQ);
    usr_rtc_handler = NULL;
    rt_release_irq(RTC_IRQ);
    rtai_cli();
    CMOS_WRITE(CMOS_READ(RTC_FREQ_SELECT), RTC_FREQ_SELECT);
    CMOS_WRITE(CMOS_READ(RTC_CONTROL),     RTC_CONTROL);
    rtai_sti();
    return;
}

EXPORT_SYMBOL(rt_request_rtc);
EXPORT_SYMBOL(rt_release_rtc);

#endif /* INCLUDED_BY_HAL_C */

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