mc146818rtc.c.svn-base

我们自己开发的一个OSEK操作系统！不知道可不可以？

/*
 * QEMU MC146818 RTC emulation
 *
 * Copyright (c) 2003-2004 Fabrice Bellard
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
#include "hw.h"
#include "qemu-timer.h"
#include "sysemu.h"
#include "pc.h"
#include "isa.h"

//#define DEBUG_CMOS

#define RTC_SECONDS             0
#define RTC_SECONDS_ALARM       1
#define RTC_MINUTES             2
#define RTC_MINUTES_ALARM       3
#define RTC_HOURS               4
#define RTC_HOURS_ALARM         5
#define RTC_ALARM_DONT_CARE    0xC0

#define RTC_DAY_OF_WEEK         6
#define RTC_DAY_OF_MONTH        7
#define RTC_MONTH               8
#define RTC_YEAR                9

#define RTC_REG_A               10
#define RTC_REG_B               11
#define RTC_REG_C               12
#define RTC_REG_D               13

#define REG_A_UIP 0x80

#define REG_B_SET 0x80
#define REG_B_PIE 0x40
#define REG_B_AIE 0x20
#define REG_B_UIE 0x10

struct RTCState {
    uint8_t cmos_data[128];
    uint8_t cmos_index;
    struct tm current_tm;
    qemu_irq irq;
    target_phys_addr_t base;
    int it_shift;
    /* periodic timer */
    QEMUTimer *periodic_timer;
    int64_t next_periodic_time;
    /* second update */
    int64_t next_second_time;
    QEMUTimer *second_timer;
    QEMUTimer *second_timer2;
};

static void rtc_set_time(RTCState *s);
static void rtc_copy_date(RTCState *s);

static void rtc_timer_update(RTCState *s, int64_t current_time)
{
    int period_code, period;
    int64_t cur_clock, next_irq_clock;

    period_code = s->cmos_data[RTC_REG_A] & 0x0f;
    if (period_code != 0 &&
        (s->cmos_data[RTC_REG_B] & REG_B_PIE)) {
        if (period_code <= 2)
            period_code += 7;
        /* period in 32 Khz cycles */
        period = 1 << (period_code - 1);
        /* compute 32 khz clock */
        cur_clock = muldiv64(current_time, 32768, ticks_per_sec);
        next_irq_clock = (cur_clock & ~(period - 1)) + period;
        s->next_periodic_time = muldiv64(next_irq_clock, ticks_per_sec, 32768) + 1;
        qemu_mod_timer(s->periodic_timer, s->next_periodic_time);
    } else {
        qemu_del_timer(s->periodic_timer);
    }
}

static void rtc_periodic_timer(void *opaque)
{
    RTCState *s = opaque;

    rtc_timer_update(s, s->next_periodic_time);
    s->cmos_data[RTC_REG_C] |= 0xc0;
    qemu_irq_raise(s->irq);
}

static void cmos_ioport_write(void *opaque, uint32_t addr, uint32_t data)
{
    RTCState *s = opaque;

    if ((addr & 1) == 0) {
        s->cmos_index = data & 0x7f;
    } else {
#ifdef DEBUG_CMOS
        printf("cmos: write index=0x%02x val=0x%02x\n",
               s->cmos_index, data);
#endif
        switch(s->cmos_index) {
        case RTC_SECONDS_ALARM:
        case RTC_MINUTES_ALARM:
        case RTC_HOURS_ALARM:
            /* XXX: not supported */
            s->cmos_data[s->cmos_index] = data;
            break;
        case RTC_SECONDS:
        case RTC_MINUTES:
        case RTC_HOURS:
        case RTC_DAY_OF_WEEK:
        case RTC_DAY_OF_MONTH:
        case RTC_MONTH:
        case RTC_YEAR:
            s->cmos_data[s->cmos_index] = data;
            /* if in set mode, do not update the time */
            if (!(s->cmos_data[RTC_REG_B] & REG_B_SET)) {
                rtc_set_time(s);
            }
            break;
        case RTC_REG_A:
            /* UIP bit is read only */
            s->cmos_data[RTC_REG_A] = (data & ~REG_A_UIP) |
                (s->cmos_data[RTC_REG_A] & REG_A_UIP);
            rtc_timer_update(s, qemu_get_clock(vm_clock));
            break;
        case RTC_REG_B:
            if (data & REG_B_SET) {
                /* set mode: reset UIP mode */
                s->cmos_data[RTC_REG_A] &= ~REG_A_UIP;
                data &= ~REG_B_UIE;
            } else {
                /* if disabling set mode, update the time */
                if (s->cmos_data[RTC_REG_B] & REG_B_SET) {
                    rtc_set_time(s);
                }
            }
            s->cmos_data[RTC_REG_B] = data;
            rtc_timer_update(s, qemu_get_clock(vm_clock));
            break;
        case RTC_REG_C:
        case RTC_REG_D:
            /* cannot write to them */
            break;
        default:
            s->cmos_data[s->cmos_index] = data;
            break;
        }
    }
}

static inline int to_bcd(RTCState *s, int a)
{
    if (s->cmos_data[RTC_REG_B] & 0x04) {
        return a;
    } else {
        return ((a / 10) << 4) | (a % 10);
    }
}

static inline int from_bcd(RTCState *s, int a)
{
    if (s->cmos_data[RTC_REG_B] & 0x04) {
        return a;
    } else {
        return ((a >> 4) * 10) + (a & 0x0f);
    }
}

static void rtc_set_time(RTCState *s)
{
    struct tm *tm = &s->current_tm;

    tm->tm_sec = from_bcd(s, s->cmos_data[RTC_SECONDS]);
    tm->tm_min = from_bcd(s, s->cmos_data[RTC_MINUTES]);
    tm->tm_hour = from_bcd(s, s->cmos_data[RTC_HOURS] & 0x7f);
    if (!(s->cmos_data[RTC_REG_B] & 0x02) &&
        (s->cmos_data[RTC_HOURS] & 0x80)) {
        tm->tm_hour += 12;
    }
    tm->tm_wday = from_bcd(s, s->cmos_data[RTC_DAY_OF_WEEK]);
    tm->tm_mday = from_bcd(s, s->cmos_data[RTC_DAY_OF_MONTH]);
    tm->tm_mon = from_bcd(s, s->cmos_data[RTC_MONTH]) - 1;
    tm->tm_year = from_bcd(s, s->cmos_data[RTC_YEAR]) + 100;
}

static void rtc_copy_date(RTCState *s)
{
    const struct tm *tm = &s->current_tm;

    s->cmos_data[RTC_SECONDS] = to_bcd(s, tm->tm_sec);
    s->cmos_data[RTC_MINUTES] = to_bcd(s, tm->tm_min);
    if (s->cmos_data[RTC_REG_B] & 0x02) {
        /* 24 hour format */
        s->cmos_data[RTC_HOURS] = to_bcd(s, tm->tm_hour);
    } else {
        /* 12 hour format */
        s->cmos_data[RTC_HOURS] = to_bcd(s, tm->tm_hour % 12);
        if (tm->tm_hour >= 12)
            s->cmos_data[RTC_HOURS] |= 0x80;
    }
    s->cmos_data[RTC_DAY_OF_WEEK] = to_bcd(s, tm->tm_wday);
    s->cmos_data[RTC_DAY_OF_MONTH] = to_bcd(s, tm->tm_mday);
    s->cmos_data[RTC_MONTH] = to_bcd(s, tm->tm_mon + 1);
    s->cmos_data[RTC_YEAR] = to_bcd(s, tm->tm_year % 100);
}

/* month is between 0 and 11. */
static int get_days_in_month(int month, int year)
{
    static const int days_tab[12] = {
        31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
    };
    int d;
    if ((unsigned )month >= 12)
        return 31;
    d = days_tab[month];
    if (month == 1) {
        if ((year % 4) == 0 && ((year % 100) != 0 || (year % 400) == 0))
            d++;
    }
    return d;
}

/* update 'tm' to the next second */
static void rtc_next_second(struct tm *tm)
{
    int days_in_month;

    tm->tm_sec++;
    if ((unsigned)tm->tm_sec >= 60) {
        tm->tm_sec = 0;
        tm->tm_min++;
        if ((unsigned)tm->tm_min >= 60) {
            tm->tm_min = 0;
            tm->tm_hour++;
            if ((unsigned)tm->tm_hour >= 24) {
                tm->tm_hour = 0;
                /* next day */
                tm->tm_wday++;
                if ((unsigned)tm->tm_wday >= 7)
                    tm->tm_wday = 0;
                days_in_month = get_days_in_month(tm->tm_mon,
                                                  tm->tm_year + 1900);
                tm->tm_mday++;
                if (tm->tm_mday < 1) {
                    tm->tm_mday = 1;
                } else if (tm->tm_mday > days_in_month) {
                    tm->tm_mday = 1;
                    tm->tm_mon++;
                    if (tm->tm_mon >= 12) {
                        tm->tm_mon = 0;
                        tm->tm_year++;
                    }
                }
            }
        }
    }
}


static void rtc_update_second(void *opaque)
{
    RTCState *s = opaque;
    int64_t delay;

    /* if the oscillator is not in normal operation, we do not update */
    if ((s->cmos_data[RTC_REG_A] & 0x70) != 0x20) {
        s->next_second_time += ticks_per_sec;
        qemu_mod_timer(s->second_timer, s->next_second_time);
    } else {
        rtc_next_second(&s->current_tm);

        if (!(s->cmos_data[RTC_REG_B] & REG_B_SET)) {
            /* update in progress bit */
            s->cmos_data[RTC_REG_A] |= REG_A_UIP;
        }
        /* should be 244 us = 8 / 32768 seconds, but currently the
           timers do not have the necessary resolution. */
        delay = (ticks_per_sec * 1) / 100;
        if (delay < 1)
            delay = 1;
        qemu_mod_timer(s->second_timer2,
                       s->next_second_time + delay);
    }
}