Archipelago » qemu

/*

 * 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 "mc146818rtc.h"

#ifdef TARGET_I386

#include "apic.h"

#endif

//#define DEBUG_CMOS

//#define DEBUG_COALESCED

#ifdef DEBUG_CMOS

# define CMOS_DPRINTF(format, ...)      printf(format, ## __VA_ARGS__)

#else

# define CMOS_DPRINTF(format, ...)      do { } while (0)

#endif

#ifdef DEBUG_COALESCED

# define DPRINTF_C(format, ...)      printf(format, ## __VA_ARGS__)

#else

# define DPRINTF_C(format, ...)      do { } while (0)

#endif

#define NSEC_PER_SEC    1000000000LL

#define SEC_PER_MIN     60

#define MIN_PER_HOUR    60

#define SEC_PER_HOUR    3600

#define HOUR_PER_DAY    24

#define SEC_PER_DAY     86400

#define RTC_REINJECT_ON_ACK_COUNT 20

#define RTC_CLOCK_RATE            32768

#define UIP_HOLD_LENGTH           (8 * NSEC_PER_SEC / 32768)

typedef struct RTCState {

    ISADevice dev;

    MemoryRegion io;

    uint8_t cmos_data[128];

    uint8_t cmos_index;

    int32_t base_year;

    uint64_t base_rtc;

    uint64_t last_update;

    int64_t offset;

    qemu_irq irq;

    qemu_irq sqw_irq;

    int it_shift;

    /* periodic timer */

    QEMUTimer *periodic_timer;

    int64_t next_periodic_time;

    /* update-ended timer */

    QEMUTimer *update_timer;

    uint64_t next_alarm_time;

    uint16_t irq_reinject_on_ack_count;

    uint32_t irq_coalesced;

    uint32_t period;

    QEMUTimer *coalesced_timer;

    Notifier clock_reset_notifier;

    LostTickPolicy lost_tick_policy;

    Notifier suspend_notifier;

} RTCState;

static void rtc_set_time(RTCState *s);

static void rtc_update_time(RTCState *s);

static void rtc_set_cmos(RTCState *s, const struct tm *tm);

static inline int rtc_from_bcd(RTCState *s, int a);

static uint64_t get_next_alarm(RTCState *s);

static inline bool rtc_running(RTCState *s)

{

    return (!(s->cmos_data[RTC_REG_B] & REG_B_SET) &&

            (s->cmos_data[RTC_REG_A] & 0x70) <= 0x20);

}

static uint64_t get_guest_rtc_ns(RTCState *s)

{

    uint64_t guest_rtc;

    uint64_t guest_clock = qemu_get_clock_ns(rtc_clock);

    guest_rtc = s->base_rtc * NSEC_PER_SEC

                 + guest_clock - s->last_update + s->offset;

    return guest_rtc;

}

#ifdef TARGET_I386

static void rtc_coalesced_timer_update(RTCState *s)

{

    if (s->irq_coalesced == 0) {

        qemu_del_timer(s->coalesced_timer);

    } else {

        /* divide each RTC interval to 2 - 8 smaller intervals */

        int c = MIN(s->irq_coalesced, 7) + 1; 

        int64_t next_clock = qemu_get_clock_ns(rtc_clock) +

            muldiv64(s->period / c, get_ticks_per_sec(), RTC_CLOCK_RATE);

        qemu_mod_timer(s->coalesced_timer, next_clock);

    }

}

static void rtc_coalesced_timer(void *opaque)

{

    RTCState *s = opaque;

    if (s->irq_coalesced != 0) {

        apic_reset_irq_delivered();

        s->cmos_data[RTC_REG_C] |= 0xc0;

        DPRINTF_C("cmos: injecting from timer\n");

        qemu_irq_raise(s->irq);

        if (apic_get_irq_delivered()) {

            s->irq_coalesced--;

            DPRINTF_C("cmos: coalesced irqs decreased to %d\n",

                      s->irq_coalesced);

        }

    }

    rtc_coalesced_timer_update(s);

}

#endif

/* handle periodic timer */

static void periodic_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)

            || ((s->cmos_data[RTC_REG_B] & REG_B_SQWE) && s->sqw_irq))) {

        if (period_code <= 2)

            period_code += 7;

        /* period in 32 Khz cycles */

        period = 1 << (period_code - 1);

#ifdef TARGET_I386

        if (period != s->period) {

            s->irq_coalesced = (s->irq_coalesced * s->period) / period;

            DPRINTF_C("cmos: coalesced irqs scaled to %d\n", s->irq_coalesced);

        }

        s->period = period;

#endif

        /* compute 32 khz clock */

        cur_clock = muldiv64(current_time, RTC_CLOCK_RATE, get_ticks_per_sec());

        next_irq_clock = (cur_clock & ~(period - 1)) + period;

        s->next_periodic_time =

            muldiv64(next_irq_clock, get_ticks_per_sec(), RTC_CLOCK_RATE) + 1;

        qemu_mod_timer(s->periodic_timer, s->next_periodic_time);

    } else {

#ifdef TARGET_I386

        s->irq_coalesced = 0;

#endif

        qemu_del_timer(s->periodic_timer);

    }

}

static void rtc_periodic_timer(void *opaque)

{

    RTCState *s = opaque;

    periodic_timer_update(s, s->next_periodic_time);

    s->cmos_data[RTC_REG_C] |= REG_C_PF;

    if (s->cmos_data[RTC_REG_B] & REG_B_PIE) {

        s->cmos_data[RTC_REG_C] |= REG_C_IRQF;

#ifdef TARGET_I386

        if (s->lost_tick_policy == LOST_TICK_SLEW) {

            if (s->irq_reinject_on_ack_count >= RTC_REINJECT_ON_ACK_COUNT)

                s->irq_reinject_on_ack_count = 0;                

            apic_reset_irq_delivered();

            qemu_irq_raise(s->irq);

            if (!apic_get_irq_delivered()) {

                s->irq_coalesced++;

                rtc_coalesced_timer_update(s);

                DPRINTF_C("cmos: coalesced irqs increased to %d\n",

                          s->irq_coalesced);

            }

        } else

#endif

        qemu_irq_raise(s->irq);

    }

    if (s->cmos_data[RTC_REG_B] & REG_B_SQWE) {

        /* Not square wave at all but we don't want 2048Hz interrupts!

           Must be seen as a pulse.  */

        qemu_irq_raise(s->sqw_irq);

    }

}

/* handle update-ended timer */

static void check_update_timer(RTCState *s)

{

    uint64_t next_update_time;

    uint64_t guest_nsec;

    int next_alarm_sec;

    /* From the data sheet: "Holding the dividers in reset prevents

     * interrupts from operating, while setting the SET bit allows"

     * them to occur.  However, it will prevent an alarm interrupt

     * from occurring, because the time of day is not updated.

     */

    if ((s->cmos_data[RTC_REG_A] & 0x60) == 0x60) {

        qemu_del_timer(s->update_timer);

        return;

    }

    if ((s->cmos_data[RTC_REG_C] & REG_C_UF) &&

        (s->cmos_data[RTC_REG_B] & REG_B_SET)) {

        qemu_del_timer(s->update_timer);

        return;

    }

    if ((s->cmos_data[RTC_REG_C] & REG_C_UF) &&

        (s->cmos_data[RTC_REG_C] & REG_C_AF)) {

        qemu_del_timer(s->update_timer);

        return;

    }

    guest_nsec = get_guest_rtc_ns(s) % NSEC_PER_SEC;

    /* if UF is clear, reprogram to next second */

    next_update_time = qemu_get_clock_ns(rtc_clock)

        + NSEC_PER_SEC - guest_nsec;

    /* Compute time of next alarm.  One second is already accounted

     * for in next_update_time.

     */

    next_alarm_sec = get_next_alarm(s);

    s->next_alarm_time = next_update_time + (next_alarm_sec - 1) * NSEC_PER_SEC;

    if (s->cmos_data[RTC_REG_C] & REG_C_UF) {

        /* UF is set, but AF is clear.  Program the timer to target

         * the alarm time.  */

        next_update_time = s->next_alarm_time;

    }

    if (next_update_time != qemu_timer_expire_time_ns(s->update_timer)) {

        qemu_mod_timer(s->update_timer, next_update_time);

    }

}

static inline uint8_t convert_hour(RTCState *s, uint8_t hour)

{

    if (!(s->cmos_data[RTC_REG_B] & REG_B_24H)) {

        hour %= 12;

        if (s->cmos_data[RTC_HOURS] & 0x80) {

            hour += 12;

        }

    }

    return hour;

}

static uint64_t get_next_alarm(RTCState *s)

{

    int32_t alarm_sec, alarm_min, alarm_hour, cur_hour, cur_min, cur_sec;

    int32_t hour, min, sec;

    rtc_update_time(s);

    alarm_sec = rtc_from_bcd(s, s->cmos_data[RTC_SECONDS_ALARM]);

    alarm_min = rtc_from_bcd(s, s->cmos_data[RTC_MINUTES_ALARM]);

    alarm_hour = rtc_from_bcd(s, s->cmos_data[RTC_HOURS_ALARM]);

    alarm_hour = alarm_hour == -1 ? -1 : convert_hour(s, alarm_hour);

    cur_sec = rtc_from_bcd(s, s->cmos_data[RTC_SECONDS]);

    cur_min = rtc_from_bcd(s, s->cmos_data[RTC_MINUTES]);

    cur_hour = rtc_from_bcd(s, s->cmos_data[RTC_HOURS]);

    cur_hour = convert_hour(s, cur_hour);

    if (alarm_hour == -1) {

        alarm_hour = cur_hour;

        if (alarm_min == -1) {

            alarm_min = cur_min;

            if (alarm_sec == -1) {

                alarm_sec = cur_sec + 1;

            } else if (cur_sec > alarm_sec) {

                alarm_min++;

            }

        } else if (cur_min == alarm_min) {

            if (alarm_sec == -1) {

                alarm_sec = cur_sec + 1;

            } else {

                if (cur_sec > alarm_sec) {

                    alarm_hour++;

                }

            }

            if (alarm_sec == SEC_PER_MIN) {

                /* wrap to next hour, minutes is not in don't care mode */

                alarm_sec = 0;

                alarm_hour++;

            }

        } else if (cur_min > alarm_min) {

            alarm_hour++;

        }

    } else if (cur_hour == alarm_hour) {

        if (alarm_min == -1) {

            alarm_min = cur_min;

            if (alarm_sec == -1) {

                alarm_sec = cur_sec + 1;

            } else if (cur_sec > alarm_sec) {

                alarm_min++;

            }

            if (alarm_sec == SEC_PER_MIN) {

                alarm_sec = 0;

                alarm_min++;

            }

            /* wrap to next day, hour is not in don't care mode */

            alarm_min %= MIN_PER_HOUR;

        } else if (cur_min == alarm_min) {

            if (alarm_sec == -1) {

                alarm_sec = cur_sec + 1;

            }

            /* wrap to next day, hours+minutes not in don't care mode */

            alarm_sec %= SEC_PER_MIN;

        }

    }

    /* values that are still don't care fire at the next min/sec */

    if (alarm_min == -1) {

        alarm_min = 0;

    }

    if (alarm_sec == -1) {

        alarm_sec = 0;

    }

    /* keep values in range */

    if (alarm_sec == SEC_PER_MIN) {

        alarm_sec = 0;

        alarm_min++;

    }

    if (alarm_min == MIN_PER_HOUR) {

        alarm_min = 0;

        alarm_hour++;

    }

    alarm_hour %= HOUR_PER_DAY;

    hour = alarm_hour - cur_hour;

    min = hour * MIN_PER_HOUR + alarm_min - cur_min;

    sec = min * SEC_PER_MIN + alarm_sec - cur_sec;

    return sec <= 0 ? sec + SEC_PER_DAY : sec;

}

static void rtc_update_timer(void *opaque)

{

    RTCState *s = opaque;

    int32_t irqs = REG_C_UF;

    int32_t new_irqs;

    assert((s->cmos_data[RTC_REG_A] & 0x60) != 0x60);

    /* UIP might have been latched, update time and clear it.  */

    rtc_update_time(s);

    s->cmos_data[RTC_REG_A] &= ~REG_A_UIP;

    if (qemu_get_clock_ns(rtc_clock) >= s->next_alarm_time) {

        irqs |= REG_C_AF;

        if (s->cmos_data[RTC_REG_B] & REG_B_AIE) {

            qemu_system_wakeup_request(QEMU_WAKEUP_REASON_RTC);

        }

    }

    new_irqs = irqs & ~s->cmos_data[RTC_REG_C];

    s->cmos_data[RTC_REG_C] |= irqs;

    if ((new_irqs & s->cmos_data[RTC_REG_B]) != 0) {

        s->cmos_data[RTC_REG_C] |= REG_C_IRQF;

        qemu_irq_raise(s->irq);

    }

    check_update_timer(s);

}

static void cmos_ioport_write(void *opaque, hwaddr addr,

                              uint64_t data, unsigned size)

{

    RTCState *s = opaque;

    if ((addr & 1) == 0) {

        s->cmos_index = data & 0x7f;

    } else {

        CMOS_DPRINTF("cmos: write index=0x%02x val=0x%02x\n",

                     s->cmos_index, data);

        switch(s->cmos_index) {

        case RTC_SECONDS_ALARM:

        case RTC_MINUTES_ALARM:

        case RTC_HOURS_ALARM:

            s->cmos_data[s->cmos_index] = data;

            check_update_timer(s);

            break;

        case RTC_IBM_PS2_CENTURY_BYTE:

            s->cmos_index = RTC_CENTURY;

            /* fall through */

        case RTC_CENTURY:

        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 (rtc_running(s)) {

                rtc_set_time(s);

                check_update_timer(s);

            }

            break;

        case RTC_REG_A:

            if ((data & 0x60) == 0x60) {

                if (rtc_running(s)) {

                    rtc_update_time(s);

                }

                /* What happens to UIP when divider reset is enabled is

                 * unclear from the datasheet.  Shouldn't matter much

                 * though.

                 */

                s->cmos_data[RTC_REG_A] &= ~REG_A_UIP;

            } else if (((s->cmos_data[RTC_REG_A] & 0x60) == 0x60) &&

                    (data & 0x70)  <= 0x20) {

                /* when the divider reset is removed, the first update cycle

                 * begins one-half second later*/

                if (!(s->cmos_data[RTC_REG_B] & REG_B_SET)) {

                    s->offset = 500000000;

                    rtc_set_time(s);

                }

                s->cmos_data[RTC_REG_A] &= ~REG_A_UIP;

            }

            /* UIP bit is read only */

            s->cmos_data[RTC_REG_A] = (data & ~REG_A_UIP) |

                (s->cmos_data[RTC_REG_A] & REG_A_UIP);

            periodic_timer_update(s, qemu_get_clock_ns(rtc_clock));

            check_update_timer(s);

            break;

        case RTC_REG_B:

            if (data & REG_B_SET) {

                /* update cmos to when the rtc was stopping */

                if (rtc_running(s)) {

                    rtc_update_time(s);

                }

                /* 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) &&

                    (s->cmos_data[RTC_REG_A] & 0x70) <= 0x20) {

                    s->offset = get_guest_rtc_ns(s) % NSEC_PER_SEC;

                    rtc_set_time(s);

                }

            }

            /* if an interrupt flag is already set when the interrupt

             * becomes enabled, raise an interrupt immediately.  */

            if (data & s->cmos_data[RTC_REG_C] & REG_C_MASK) {

                s->cmos_data[RTC_REG_C] |= REG_C_IRQF;

                qemu_irq_raise(s->irq);

            } else {

                s->cmos_data[RTC_REG_C] &= ~REG_C_IRQF;

                qemu_irq_lower(s->irq);

            }

            s->cmos_data[RTC_REG_B] = data;

            periodic_timer_update(s, qemu_get_clock_ns(rtc_clock));

            check_update_timer(s);

            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 rtc_to_bcd(RTCState *s, int a)

{

    if (s->cmos_data[RTC_REG_B] & REG_B_DM) {

        return a;

    } else {

        return ((a / 10) << 4) | (a % 10);

    }

}

static inline int rtc_from_bcd(RTCState *s, int a)

{

    if ((a & 0xc0) == 0xc0) {

        return -1;

    }

    if (s->cmos_data[RTC_REG_B] & REG_B_DM) {

        return a;

    } else {

        return ((a >> 4) * 10) + (a & 0x0f);

    }

}

static void rtc_get_time(RTCState *s, struct tm *tm)

{

    tm->tm_sec = rtc_from_bcd(s, s->cmos_data[RTC_SECONDS]);

    tm->tm_min = rtc_from_bcd(s, s->cmos_data[RTC_MINUTES]);

    tm->tm_hour = rtc_from_bcd(s, s->cmos_data[RTC_HOURS] & 0x7f);

    if (!(s->cmos_data[RTC_REG_B] & REG_B_24H)) {

        tm->tm_hour %= 12;

        if (s->cmos_data[RTC_HOURS] & 0x80) {

            tm->tm_hour += 12;

        }

    }

    tm->tm_wday = rtc_from_bcd(s, s->cmos_data[RTC_DAY_OF_WEEK]) - 1;

    tm->tm_mday = rtc_from_bcd(s, s->cmos_data[RTC_DAY_OF_MONTH]);

    tm->tm_mon = rtc_from_bcd(s, s->cmos_data[RTC_MONTH]) - 1;

    tm->tm_year =

        rtc_from_bcd(s, s->cmos_data[RTC_YEAR]) + s->base_year +

        rtc_from_bcd(s, s->cmos_data[RTC_CENTURY]) * 100 - 1900;

}

static void rtc_set_time(RTCState *s)

{

    struct tm tm;

    rtc_get_time(s, &tm);

    s->base_rtc = mktimegm(&tm);

    s->last_update = qemu_get_clock_ns(rtc_clock);

    rtc_change_mon_event(&tm);

}

static void rtc_set_cmos(RTCState *s, const struct tm *tm)

{

    int year;

    s->cmos_data[RTC_SECONDS] = rtc_to_bcd(s, tm->tm_sec);

    s->cmos_data[RTC_MINUTES] = rtc_to_bcd(s, tm->tm_min);

    if (s->cmos_data[RTC_REG_B] & REG_B_24H) {

        /* 24 hour format */

        s->cmos_data[RTC_HOURS] = rtc_to_bcd(s, tm->tm_hour);

    } else {

        /* 12 hour format */

        int h = (tm->tm_hour % 12) ? tm->tm_hour % 12 : 12;

        s->cmos_data[RTC_HOURS] = rtc_to_bcd(s, h);

        if (tm->tm_hour >= 12)

            s->cmos_data[RTC_HOURS] |= 0x80;

    }

    s->cmos_data[RTC_DAY_OF_WEEK] = rtc_to_bcd(s, tm->tm_wday + 1);

    s->cmos_data[RTC_DAY_OF_MONTH] = rtc_to_bcd(s, tm->tm_mday);

    s->cmos_data[RTC_MONTH] = rtc_to_bcd(s, tm->tm_mon + 1);

    year = tm->tm_year + 1900 - s->base_year;

    s->cmos_data[RTC_YEAR] = rtc_to_bcd(s, year % 100);

    s->cmos_data[RTC_CENTURY] = rtc_to_bcd(s, year / 100);

}

static void rtc_update_time(RTCState *s)

{

    struct tm ret;

    time_t guest_sec;

    int64_t guest_nsec;

    guest_nsec = get_guest_rtc_ns(s);

    guest_sec = guest_nsec / NSEC_PER_SEC;

    gmtime_r(&guest_sec, &ret);

    rtc_set_cmos(s, &ret);

}

static int update_in_progress(RTCState *s)

{

    int64_t guest_nsec;

    if (!rtc_running(s)) {

        return 0;

    }

    if (qemu_timer_pending(s->update_timer)) {

        int64_t next_update_time = qemu_timer_expire_time_ns(s->update_timer);

        /* Latch UIP until the timer expires.  */

        if (qemu_get_clock_ns(rtc_clock) >= (next_update_time - UIP_HOLD_LENGTH)) {

            s->cmos_data[RTC_REG_A] |= REG_A_UIP;

            return 1;

        }

    }

    guest_nsec = get_guest_rtc_ns(s);

    /* UIP bit will be set at last 244us of every second. */

    if ((guest_nsec % NSEC_PER_SEC) >= (NSEC_PER_SEC - UIP_HOLD_LENGTH)) {

        return 1;

    }

    return 0;

}

static uint64_t cmos_ioport_read(void *opaque, hwaddr addr,

                                 unsigned size)

{

    RTCState *s = opaque;

    int ret;

    if ((addr & 1) == 0) {

        return 0xff;

    } else {

        switch(s->cmos_index) {

        case RTC_IBM_PS2_CENTURY_BYTE:

            s->cmos_index = RTC_CENTURY;

            /* fall through */

        case RTC_CENTURY:

        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:

            /* if not in set mode, calibrate cmos before

             * reading*/

            if (rtc_running(s)) {

                rtc_update_time(s);

            }

            ret = s->cmos_data[s->cmos_index];

            break;

        case RTC_REG_A:

            if (update_in_progress(s)) {

                s->cmos_data[s->cmos_index] |= REG_A_UIP;

            } else {

                s->cmos_data[s->cmos_index] &= ~REG_A_UIP;

            }

            ret = s->cmos_data[s->cmos_index];

            break;

        case RTC_REG_C:

            ret = s->cmos_data[s->cmos_index];

            qemu_irq_lower(s->irq);

            s->cmos_data[RTC_REG_C] = 0x00;

            if (ret & (REG_C_UF | REG_C_AF)) {

                check_update_timer(s);

            }

#ifdef TARGET_I386

            if(s->irq_coalesced &&

                    (s->cmos_data[RTC_REG_B] & REG_B_PIE) &&

                    s->irq_reinject_on_ack_count < RTC_REINJECT_ON_ACK_COUNT) {

                s->irq_reinject_on_ack_count++;

                s->cmos_data[RTC_REG_C] |= REG_C_IRQF | REG_C_PF;

                apic_reset_irq_delivered();

                DPRINTF_C("cmos: injecting on ack\n");

                qemu_irq_raise(s->irq);

                if (apic_get_irq_delivered()) {

                    s->irq_coalesced--;

                    DPRINTF_C("cmos: coalesced irqs decreased to %d\n",

                              s->irq_coalesced);

                }

            }

#endif

            break;

        default:

            ret = s->cmos_data[s->cmos_index];

            break;

        }

        CMOS_DPRINTF("cmos: read index=0x%02x val=0x%02x\n",

                     s->cmos_index, ret);

        return ret;

    }

}

void rtc_set_memory(ISADevice *dev, int addr, int val)

{

    RTCState *s = DO_UPCAST(RTCState, dev, dev);

    if (addr >= 0 && addr <= 127)

        s->cmos_data[addr] = val;

}

static void rtc_set_date_from_host(ISADevice *dev)

{

    RTCState *s = DO_UPCAST(RTCState, dev, dev);

    struct tm tm;

    qemu_get_timedate(&tm, 0);

    s->base_rtc = mktimegm(&tm);

    s->last_update = qemu_get_clock_ns(rtc_clock);

    s->offset = 0;

    /* set the CMOS date */

    rtc_set_cmos(s, &tm);

}

static int rtc_post_load(void *opaque, int version_id)

{

    RTCState *s = opaque;

    if (version_id <= 2) {

        rtc_set_time(s);

        s->offset = 0;

        check_update_timer(s);

    }

#ifdef TARGET_I386

    if (version_id >= 2) {

        if (s->lost_tick_policy == LOST_TICK_SLEW) {

            rtc_coalesced_timer_update(s);

        }

    }

#endif

    return 0;

}

static const VMStateDescription vmstate_rtc = {

    .name = "mc146818rtc",

    .version_id = 3,

    .minimum_version_id = 1,

    .minimum_version_id_old = 1,

    .post_load = rtc_post_load,

    .fields      = (VMStateField []) {

        VMSTATE_BUFFER(cmos_data, RTCState),

        VMSTATE_UINT8(cmos_index, RTCState),

        VMSTATE_UNUSED(7*4),

        VMSTATE_TIMER(periodic_timer, RTCState),

        VMSTATE_INT64(next_periodic_time, RTCState),

        VMSTATE_UNUSED(3*8),

        VMSTATE_UINT32_V(irq_coalesced, RTCState, 2),

        VMSTATE_UINT32_V(period, RTCState, 2),

        VMSTATE_UINT64_V(base_rtc, RTCState, 3),

        VMSTATE_UINT64_V(last_update, RTCState, 3),

        VMSTATE_INT64_V(offset, RTCState, 3),

        VMSTATE_TIMER_V(update_timer, RTCState, 3),

        VMSTATE_UINT64_V(next_alarm_time, RTCState, 3),

        VMSTATE_END_OF_LIST()

    }

};

static void rtc_notify_clock_reset(Notifier *notifier, void *data)

{

    RTCState *s = container_of(notifier, RTCState, clock_reset_notifier);

    int64_t now = *(int64_t *)data;

    rtc_set_date_from_host(&s->dev);

    periodic_timer_update(s, now);

    check_update_timer(s);

#ifdef TARGET_I386

    if (s->lost_tick_policy == LOST_TICK_SLEW) {

        rtc_coalesced_timer_update(s);

    }

#endif

}

/* set CMOS shutdown status register (index 0xF) as S3_resume(0xFE)

   BIOS will read it and start S3 resume at POST Entry */

static void rtc_notify_suspend(Notifier *notifier, void *data)

{

    RTCState *s = container_of(notifier, RTCState, suspend_notifier);

    rtc_set_memory(&s->dev, 0xF, 0xFE);

}

static void rtc_reset(void *opaque)

{

    RTCState *s = opaque;

    s->cmos_data[RTC_REG_B] &= ~(REG_B_PIE | REG_B_AIE | REG_B_SQWE);

    s->cmos_data[RTC_REG_C] &= ~(REG_C_UF | REG_C_IRQF | REG_C_PF | REG_C_AF);

    check_update_timer(s);

    qemu_irq_lower(s->irq);

#ifdef TARGET_I386

    if (s->lost_tick_policy == LOST_TICK_SLEW) {

        s->irq_coalesced = 0;

    }

#endif

}

static const MemoryRegionOps cmos_ops = {

    .read = cmos_ioport_read,

    .write = cmos_ioport_write,

    .impl = {

        .min_access_size = 1,

        .max_access_size = 1,

    },

    .endianness = DEVICE_LITTLE_ENDIAN,

};

static void rtc_get_date(Object *obj, Visitor *v, void *opaque,

                         const char *name, Error **errp)

{

    ISADevice *isa = ISA_DEVICE(obj);

    RTCState *s = DO_UPCAST(RTCState, dev, isa);

    struct tm current_tm;

    rtc_update_time(s);

    rtc_get_time(s, &current_tm);

    visit_start_struct(v, NULL, "struct tm", name, 0, errp);

    visit_type_int32(v, &current_tm.tm_year, "tm_year", errp);

    visit_type_int32(v, &current_tm.tm_mon, "tm_mon", errp);

    visit_type_int32(v, &current_tm.tm_mday, "tm_mday", errp);

    visit_type_int32(v, &current_tm.tm_hour, "tm_hour", errp);

    visit_type_int32(v, &current_tm.tm_min, "tm_min", errp);

    visit_type_int32(v, &current_tm.tm_sec, "tm_sec", errp);

    visit_end_struct(v, errp);

}

static int rtc_initfn(ISADevice *dev)

{

    RTCState *s = DO_UPCAST(RTCState, dev, dev);

    int base = 0x70;

    s->cmos_data[RTC_REG_A] = 0x26;

    s->cmos_data[RTC_REG_B] = 0x02;

    s->cmos_data[RTC_REG_C] = 0x00;

    s->cmos_data[RTC_REG_D] = 0x80;

    /* This is for historical reasons.  The default base year qdev property

     * was set to 2000 for most machine types before the century byte was

     * implemented.

     *

     * This if statement means that the century byte will be always 0

     * (at least until 2079...) for base_year = 1980, but will be set

     * correctly for base_year = 2000.

     */

    if (s->base_year == 2000) {

        s->base_year = 0;

    }

    rtc_set_date_from_host(dev);

#ifdef TARGET_I386

    switch (s->lost_tick_policy) {

    case LOST_TICK_SLEW:

        s->coalesced_timer =

            qemu_new_timer_ns(rtc_clock, rtc_coalesced_timer, s);

        break;

    case LOST_TICK_DISCARD:

        break;

    default:

        return -EINVAL;

    }

#endif

    s->periodic_timer = qemu_new_timer_ns(rtc_clock, rtc_periodic_timer, s);

    s->update_timer = qemu_new_timer_ns(rtc_clock, rtc_update_timer, s);

    check_update_timer(s);

    s->clock_reset_notifier.notify = rtc_notify_clock_reset;

    qemu_register_clock_reset_notifier(rtc_clock, &s->clock_reset_notifier);

    s->suspend_notifier.notify = rtc_notify_suspend;

    qemu_register_suspend_notifier(&s->suspend_notifier);

    memory_region_init_io(&s->io, &cmos_ops, s, "rtc", 2);

    isa_register_ioport(dev, &s->io, base);

    qdev_set_legacy_instance_id(&dev->qdev, base, 3);

    qemu_register_reset(rtc_reset, s);

    object_property_add(OBJECT(s), "date", "struct tm",

                        rtc_get_date, NULL, NULL, s, NULL);

    return 0;

}

ISADevice *rtc_init(ISABus *bus, int base_year, qemu_irq intercept_irq)

{

    ISADevice *dev;

    RTCState *s;

    dev = isa_create(bus, "mc146818rtc");

    s = DO_UPCAST(RTCState, dev, dev);

    qdev_prop_set_int32(&dev->qdev, "base_year", base_year);

    qdev_init_nofail(&dev->qdev);

    if (intercept_irq) {

        s->irq = intercept_irq;

    } else {

        isa_init_irq(dev, &s->irq, RTC_ISA_IRQ);

    }

    return dev;

}

static Property mc146818rtc_properties[] = {

    DEFINE_PROP_INT32("base_year", RTCState, base_year, 1980),

    DEFINE_PROP_LOSTTICKPOLICY("lost_tick_policy", RTCState,

                               lost_tick_policy, LOST_TICK_DISCARD),

    DEFINE_PROP_END_OF_LIST(),

};

static void rtc_class_initfn(ObjectClass *klass, void *data)

{

    DeviceClass *dc = DEVICE_CLASS(klass);

    ISADeviceClass *ic = ISA_DEVICE_CLASS(klass);

    ic->init = rtc_initfn;

    dc->no_user = 1;

    dc->vmsd = &vmstate_rtc;

    dc->props = mc146818rtc_properties;

}

static TypeInfo mc146818rtc_info = {

    .name          = "mc146818rtc",

    .parent        = TYPE_ISA_DEVICE,

    .instance_size = sizeof(RTCState),

    .class_init    = rtc_class_initfn,

};

static void mc146818rtc_register_types(void)

{

    type_register_static(&mc146818rtc_info);

}