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qemu/hw/mc146818rtc.c
Jan Kiszka 17604dac28 mc146818rtc: Handle host clock resets 
Make use of the new clock reset notifier to update the RTC whenever
rtc_clock is the host clock and that happens to jump backward. This
avoids that the RTC stalls for the period the host clock was set back.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2011-07-23 11:26:12 -05:00

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/*
* 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 "apic.h"
#include "isa.h"
#include "mc146818rtc.h"
//#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 RTC_REINJECT_ON_ACK_COUNT 20
#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
#define REG_B_SQWE 0x08
#define REG_B_DM 0x04
#define REG_B_24H 0x02
#define REG_C_UF 0x10
#define REG_C_IRQF 0x80
#define REG_C_PF 0x40
#define REG_C_AF 0x20
typedef struct RTCState {
ISADevice dev;
uint8_t cmos_data[128];
uint8_t cmos_index;
struct tm current_tm;
int32_t base_year;
qemu_irq irq;
qemu_irq sqw_irq;
int it_shift;
/* periodic timer */
QEMUTimer *periodic_timer;
int64_t next_periodic_time;
/* second update */
int64_t next_second_time;
uint16_t irq_reinject_on_ack_count;
uint32_t irq_coalesced;
uint32_t period;
QEMUTimer *coalesced_timer;
QEMUTimer *second_timer;
QEMUTimer *second_timer2;
Notifier clock_reset_notifier;
} RTCState;
static void rtc_set_time(RTCState *s);
static void rtc_copy_date(RTCState *s);
#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(), 32768);
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
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)
|| ((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, 32768, get_ticks_per_sec());
next_irq_clock = (cur_clock & ~(period - 1)) + period;
s->next_periodic_time =
muldiv64(next_irq_clock, get_ticks_per_sec(), 32768) + 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;
rtc_timer_update(s, s->next_periodic_time);
if (s->cmos_data[RTC_REG_B] & REG_B_PIE) {
s->cmos_data[RTC_REG_C] |= 0xc0;
#ifdef TARGET_I386
if(rtc_td_hack) {
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);
}
}
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 {
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;
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_ns(rtc_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);
}
}
if (((s->cmos_data[RTC_REG_B] ^ data) & (REG_B_DM | REG_B_24H)) &&
!(data & REG_B_SET)) {
/* If the time format has changed and not in set mode,
update the registers immediately. */
s->cmos_data[RTC_REG_B] = data;
rtc_copy_date(s);
} else {
s->cmos_data[RTC_REG_B] = data;
}
rtc_timer_update(s, qemu_get_clock_ns(rtc_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 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 (s->cmos_data[RTC_REG_B] & REG_B_DM) {
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 = 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) &&
(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 - 1900;
rtc_change_mon_event(tm);
}
static void rtc_copy_date(RTCState *s)
{
const struct tm *tm = &s->current_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 */
s->cmos_data[RTC_HOURS] = rtc_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] = 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 - s->base_year) % 100;
if (year < 0)
year += 100;
s->cmos_data[RTC_YEAR] = rtc_to_bcd(s, year);
}
/* 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 += get_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 = (get_ticks_per_sec() * 1) / 100;
if (delay < 1)
delay = 1;
qemu_mod_timer(s->second_timer2,
s->next_second_time + delay);
}
}
static void rtc_update_second2(void *opaque)
{
RTCState *s = opaque;
if (!(s->cmos_data[RTC_REG_B] & REG_B_SET)) {
rtc_copy_date(s);
}
/* check alarm */
if (s->cmos_data[RTC_REG_B] & REG_B_AIE) {
if (((s->cmos_data[RTC_SECONDS_ALARM] & 0xc0) == 0xc0 ||
rtc_from_bcd(s, s->cmos_data[RTC_SECONDS_ALARM]) == s->current_tm.tm_sec) &&
((s->cmos_data[RTC_MINUTES_ALARM] & 0xc0) == 0xc0 ||
rtc_from_bcd(s, s->cmos_data[RTC_MINUTES_ALARM]) == s->current_tm.tm_min) &&
((s->cmos_data[RTC_HOURS_ALARM] & 0xc0) == 0xc0 ||
rtc_from_bcd(s, s->cmos_data[RTC_HOURS_ALARM]) == s->current_tm.tm_hour)) {
s->cmos_data[RTC_REG_C] |= 0xa0;
qemu_irq_raise(s->irq);
}
}
/* update ended interrupt */
s->cmos_data[RTC_REG_C] |= REG_C_UF;
if (s->cmos_data[RTC_REG_B] & REG_B_UIE) {
s->cmos_data[RTC_REG_C] |= REG_C_IRQF;
qemu_irq_raise(s->irq);
}
/* clear update in progress bit */
s->cmos_data[RTC_REG_A] &= ~REG_A_UIP;
s->next_second_time += get_ticks_per_sec();
qemu_mod_timer(s->second_timer, s->next_second_time);
}
static uint32_t cmos_ioport_read(void *opaque, uint32_t addr)
{
RTCState *s = opaque;
int ret;
if ((addr & 1) == 0) {
return 0xff;
} else {
switch(s->cmos_index) {
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:
ret = s->cmos_data[s->cmos_index];
break;
case RTC_REG_A:
ret = s->cmos_data[s->cmos_index];
break;
case RTC_REG_C:
ret = s->cmos_data[s->cmos_index];
qemu_irq_lower(s->irq);
#ifdef TARGET_I386
if(s->irq_coalesced &&
s->irq_reinject_on_ack_count < RTC_REINJECT_ON_ACK_COUNT) {
s->irq_reinject_on_ack_count++;
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);
}
break;
}
#endif
s->cmos_data[RTC_REG_C] = 0x00;
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;
}
void rtc_set_date(ISADevice *dev, const struct tm *tm)
{
RTCState *s = DO_UPCAST(RTCState, dev, dev);
s->current_tm = *tm;
rtc_copy_date(s);
}
/* PC cmos mappings */
#define REG_IBM_CENTURY_BYTE 0x32
#define REG_IBM_PS2_CENTURY_BYTE 0x37
static void rtc_set_date_from_host(ISADevice *dev)
{
RTCState *s = DO_UPCAST(RTCState, dev, dev);
struct tm tm;
int val;
/* set the CMOS date */
qemu_get_timedate(&tm, 0);
rtc_set_date(dev, &tm);
val = rtc_to_bcd(s, (tm.tm_year / 100) + 19);
rtc_set_memory(dev, REG_IBM_CENTURY_BYTE, val);
rtc_set_memory(dev, REG_IBM_PS2_CENTURY_BYTE, val);
}
static int rtc_post_load(void *opaque, int version_id)
{
#ifdef TARGET_I386
RTCState *s = opaque;
if (version_id >= 2) {
if (rtc_td_hack) {
rtc_coalesced_timer_update(s);
}
}
#endif
return 0;
}
static const VMStateDescription vmstate_rtc = {
.name = "mc146818rtc",
.version_id = 2,
.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_INT32(current_tm.tm_sec, RTCState),
VMSTATE_INT32(current_tm.tm_min, RTCState),
VMSTATE_INT32(current_tm.tm_hour, RTCState),
VMSTATE_INT32(current_tm.tm_wday, RTCState),
VMSTATE_INT32(current_tm.tm_mday, RTCState),
VMSTATE_INT32(current_tm.tm_mon, RTCState),
VMSTATE_INT32(current_tm.tm_year, RTCState),
VMSTATE_TIMER(periodic_timer, RTCState),
VMSTATE_INT64(next_periodic_time, RTCState),
VMSTATE_INT64(next_second_time, RTCState),
VMSTATE_TIMER(second_timer, RTCState),
VMSTATE_TIMER(second_timer2, RTCState),
VMSTATE_UINT32_V(irq_coalesced, RTCState, 2),
VMSTATE_UINT32_V(period, RTCState, 2),
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);
s->next_second_time = now + (get_ticks_per_sec() * 99) / 100;
qemu_mod_timer(s->second_timer2, s->next_second_time);
rtc_timer_update(s, now);
#ifdef TARGET_I386
if (rtc_td_hack) {
rtc_coalesced_timer_update(s);
}
#endif
}
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);
qemu_irq_lower(s->irq);
#ifdef TARGET_I386
if (rtc_td_hack)
s->irq_coalesced = 0;
#endif
}
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;
rtc_set_date_from_host(dev);
s->periodic_timer = qemu_new_timer_ns(rtc_clock, rtc_periodic_timer, s);
#ifdef TARGET_I386
if (rtc_td_hack)
s->coalesced_timer =
qemu_new_timer_ns(rtc_clock, rtc_coalesced_timer, s);
#endif
s->second_timer = qemu_new_timer_ns(rtc_clock, rtc_update_second, s);
s->second_timer2 = qemu_new_timer_ns(rtc_clock, rtc_update_second2, s);
s->clock_reset_notifier.notify = rtc_notify_clock_reset;
qemu_register_clock_reset_notifier(rtc_clock, &s->clock_reset_notifier);
s->next_second_time =
qemu_get_clock_ns(rtc_clock) + (get_ticks_per_sec() * 99) / 100;
qemu_mod_timer(s->second_timer2, s->next_second_time);
register_ioport_write(base, 2, 1, cmos_ioport_write, s);
register_ioport_read(base, 2, 1, cmos_ioport_read, s);
isa_init_ioport_range(dev, base, 2);
qdev_set_legacy_instance_id(&dev->qdev, base, 2);
qemu_register_reset(rtc_reset, s);
return 0;
}
ISADevice *rtc_init(int base_year, qemu_irq intercept_irq)
{
ISADevice *dev;
RTCState *s;
dev = isa_create("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 ISADeviceInfo mc146818rtc_info = {
.qdev.name = "mc146818rtc",
.qdev.size = sizeof(RTCState),
.qdev.no_user = 1,
.qdev.vmsd = &vmstate_rtc,
.init = rtc_initfn,
.qdev.props = (Property[]) {
DEFINE_PROP_INT32("base_year", RTCState, base_year, 1980),
DEFINE_PROP_END_OF_LIST(),
}
};
static void mc146818rtc_register(void)
{
isa_qdev_register(&mc146818rtc_info);
}
device_init(mc146818rtc_register)
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