mc146818rtc: update periodic timer only if it is needed
Currently, the timer is updated whenever RegA or RegB is written even if the periodic timer related configuration is not changed This patch optimizes it slightly to make the update happen only if its period or enable-status is changed, also later patches are depend on this optimization Signed-off-by: Xiao Guangrong <xiaoguangrong@tencent.com> Message-Id: <20170510083259.3900-2-xiaoguangrong@tencent.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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@ -391,6 +391,7 @@ static void cmos_ioport_write(void *opaque, hwaddr addr,
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uint64_t data, unsigned size)
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uint64_t data, unsigned size)
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{
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{
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RTCState *s = opaque;
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RTCState *s = opaque;
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bool update_periodic_timer;
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if ((addr & 1) == 0) {
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if ((addr & 1) == 0) {
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s->cmos_index = data & 0x7f;
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s->cmos_index = data & 0x7f;
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@ -423,6 +424,8 @@ static void cmos_ioport_write(void *opaque, hwaddr addr,
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}
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}
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break;
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break;
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case RTC_REG_A:
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case RTC_REG_A:
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update_periodic_timer = (s->cmos_data[RTC_REG_A] ^ data) & 0x0f;
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if ((data & 0x60) == 0x60) {
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if ((data & 0x60) == 0x60) {
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if (rtc_running(s)) {
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if (rtc_running(s)) {
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rtc_update_time(s);
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rtc_update_time(s);
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@ -445,10 +448,17 @@ static void cmos_ioport_write(void *opaque, hwaddr addr,
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/* UIP bit is read only */
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/* UIP bit is read only */
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s->cmos_data[RTC_REG_A] = (data & ~REG_A_UIP) |
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s->cmos_data[RTC_REG_A] = (data & ~REG_A_UIP) |
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(s->cmos_data[RTC_REG_A] & REG_A_UIP);
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(s->cmos_data[RTC_REG_A] & REG_A_UIP);
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if (update_periodic_timer) {
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periodic_timer_update(s, qemu_clock_get_ns(rtc_clock));
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periodic_timer_update(s, qemu_clock_get_ns(rtc_clock));
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}
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check_update_timer(s);
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check_update_timer(s);
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break;
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break;
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case RTC_REG_B:
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case RTC_REG_B:
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update_periodic_timer = (s->cmos_data[RTC_REG_B] ^ data)
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& REG_B_PIE;
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if (data & REG_B_SET) {
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if (data & REG_B_SET) {
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/* update cmos to when the rtc was stopping */
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/* update cmos to when the rtc was stopping */
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if (rtc_running(s)) {
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if (rtc_running(s)) {
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@ -475,7 +485,11 @@ static void cmos_ioport_write(void *opaque, hwaddr addr,
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qemu_irq_lower(s->irq);
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qemu_irq_lower(s->irq);
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}
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}
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s->cmos_data[RTC_REG_B] = data;
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s->cmos_data[RTC_REG_B] = data;
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if (update_periodic_timer) {
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periodic_timer_update(s, qemu_clock_get_ns(rtc_clock));
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periodic_timer_update(s, qemu_clock_get_ns(rtc_clock));
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}
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check_update_timer(s);
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check_update_timer(s);
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break;
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break;
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case RTC_REG_C:
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case RTC_REG_C:
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