Fixed races accessing the RTC. The races apparently caused
apm_default_resume() to sometimes set a very wrong time.
(1) Accesses to the RTC index and data registers were not atomic enough.
Interrupts were not masked. This was only good enough until an
interrupt handler (rtcintr()) started accessing the RTC in FreeBSD-2.0.
(2) Access to the block of time registers in inittodr() was not atomic
enough. inittodr() has 244us to read the time registers. Interrupts
were not masked. This was only good enough until something (apm)
started calling inittodr() after boot time in FreeBSD-2.0.
The fix for (2) also makes the timecounter update more atomic, although
this is currently unimportant due to the low resolution of the RTC.
Problem reported by: mckay
This commit is contained in:
bde
parent
afa829033b
commit
b68c18d69f
@ -550,23 +550,30 @@ int
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rtcin(reg)
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int reg;
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{
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int s;
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u_char val;
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s = splhigh();
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outb(IO_RTC, reg);
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inb(0x84);
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val = inb(IO_RTC + 1);
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inb(0x84);
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splx(s);
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return (val);
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}
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static __inline void
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writertc(u_char reg, u_char val)
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{
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int s;
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s = splhigh();
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inb(0x84);
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outb(IO_RTC, reg);
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inb(0x84);
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outb(IO_RTC + 1, val);
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inb(0x84); /* XXX work around wrong order in rtcin() */
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splx(s);
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}
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static __inline int
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@ -847,7 +854,11 @@ inittodr(time_t base)
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/* wait for time update to complete */
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/* If RTCSA_TUP is zero, we have at least 244us before next update */
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while (rtcin(RTC_STATUSA) & RTCSA_TUP);
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s = splhigh();
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while (rtcin(RTC_STATUSA) & RTCSA_TUP) {
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splx(s);
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s = splhigh();
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}
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days = 0;
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#ifdef USE_RTC_CENTURY
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@ -857,8 +868,10 @@ inittodr(time_t base)
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if (year < 1970)
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year += 100;
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#endif
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if (year < 1970)
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if (year < 1970) {
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splx(s);
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goto wrong_time;
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}
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month = readrtc(RTC_MONTH);
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for (m = 1; m < month; m++)
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days += daysinmonth[m-1];
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@ -880,12 +893,11 @@ inittodr(time_t base)
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y = time_second - sec;
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if (y <= -2 || y >= 2) {
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/* badly off, adjust it */
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s = splclock();
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ts.tv_sec = sec;
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ts.tv_nsec = 0;
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set_timecounter(&ts);
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splx(s);
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}
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splx(s);
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return;
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wrong_time:
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@ -550,23 +550,30 @@ int
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rtcin(reg)
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int reg;
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{
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int s;
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u_char val;
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s = splhigh();
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outb(IO_RTC, reg);
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inb(0x84);
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val = inb(IO_RTC + 1);
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inb(0x84);
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splx(s);
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return (val);
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}
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static __inline void
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writertc(u_char reg, u_char val)
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{
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int s;
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s = splhigh();
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inb(0x84);
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outb(IO_RTC, reg);
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inb(0x84);
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outb(IO_RTC + 1, val);
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inb(0x84); /* XXX work around wrong order in rtcin() */
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splx(s);
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}
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static __inline int
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@ -847,7 +854,11 @@ inittodr(time_t base)
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/* wait for time update to complete */
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/* If RTCSA_TUP is zero, we have at least 244us before next update */
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while (rtcin(RTC_STATUSA) & RTCSA_TUP);
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s = splhigh();
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while (rtcin(RTC_STATUSA) & RTCSA_TUP) {
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splx(s);
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s = splhigh();
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}
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days = 0;
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#ifdef USE_RTC_CENTURY
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@ -857,8 +868,10 @@ inittodr(time_t base)
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if (year < 1970)
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year += 100;
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#endif
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if (year < 1970)
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if (year < 1970) {
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splx(s);
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goto wrong_time;
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}
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month = readrtc(RTC_MONTH);
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for (m = 1; m < month; m++)
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days += daysinmonth[m-1];
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@ -880,12 +893,11 @@ inittodr(time_t base)
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y = time_second - sec;
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if (y <= -2 || y >= 2) {
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/* badly off, adjust it */
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s = splclock();
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ts.tv_sec = sec;
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ts.tv_nsec = 0;
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set_timecounter(&ts);
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splx(s);
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}
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splx(s);
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return;
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wrong_time:
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@ -550,23 +550,30 @@ int
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rtcin(reg)
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int reg;
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{
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int s;
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u_char val;
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s = splhigh();
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outb(IO_RTC, reg);
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inb(0x84);
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val = inb(IO_RTC + 1);
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inb(0x84);
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splx(s);
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return (val);
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}
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static __inline void
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writertc(u_char reg, u_char val)
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{
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int s;
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s = splhigh();
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inb(0x84);
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outb(IO_RTC, reg);
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inb(0x84);
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outb(IO_RTC + 1, val);
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inb(0x84); /* XXX work around wrong order in rtcin() */
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splx(s);
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}
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static __inline int
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@ -847,7 +854,11 @@ inittodr(time_t base)
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/* wait for time update to complete */
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/* If RTCSA_TUP is zero, we have at least 244us before next update */
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while (rtcin(RTC_STATUSA) & RTCSA_TUP);
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s = splhigh();
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while (rtcin(RTC_STATUSA) & RTCSA_TUP) {
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splx(s);
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s = splhigh();
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}
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days = 0;
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#ifdef USE_RTC_CENTURY
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@ -857,8 +868,10 @@ inittodr(time_t base)
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if (year < 1970)
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year += 100;
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#endif
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if (year < 1970)
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if (year < 1970) {
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splx(s);
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goto wrong_time;
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}
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month = readrtc(RTC_MONTH);
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for (m = 1; m < month; m++)
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days += daysinmonth[m-1];
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@ -880,12 +893,11 @@ inittodr(time_t base)
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y = time_second - sec;
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if (y <= -2 || y >= 2) {
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/* badly off, adjust it */
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s = splclock();
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ts.tv_sec = sec;
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ts.tv_nsec = 0;
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set_timecounter(&ts);
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splx(s);
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}
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splx(s);
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return;
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wrong_time:
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@ -550,23 +550,30 @@ int
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rtcin(reg)
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int reg;
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{
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int s;
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u_char val;
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s = splhigh();
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outb(IO_RTC, reg);
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inb(0x84);
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val = inb(IO_RTC + 1);
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inb(0x84);
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splx(s);
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return (val);
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}
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static __inline void
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writertc(u_char reg, u_char val)
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{
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int s;
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s = splhigh();
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inb(0x84);
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outb(IO_RTC, reg);
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inb(0x84);
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outb(IO_RTC + 1, val);
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inb(0x84); /* XXX work around wrong order in rtcin() */
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splx(s);
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}
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static __inline int
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@ -847,7 +854,11 @@ inittodr(time_t base)
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/* wait for time update to complete */
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/* If RTCSA_TUP is zero, we have at least 244us before next update */
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while (rtcin(RTC_STATUSA) & RTCSA_TUP);
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s = splhigh();
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while (rtcin(RTC_STATUSA) & RTCSA_TUP) {
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splx(s);
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s = splhigh();
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}
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days = 0;
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#ifdef USE_RTC_CENTURY
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@ -857,8 +868,10 @@ inittodr(time_t base)
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if (year < 1970)
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year += 100;
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#endif
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if (year < 1970)
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if (year < 1970) {
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splx(s);
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goto wrong_time;
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}
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month = readrtc(RTC_MONTH);
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for (m = 1; m < month; m++)
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days += daysinmonth[m-1];
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@ -880,12 +893,11 @@ inittodr(time_t base)
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y = time_second - sec;
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if (y <= -2 || y >= 2) {
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/* badly off, adjust it */
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s = splclock();
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ts.tv_sec = sec;
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ts.tv_nsec = 0;
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set_timecounter(&ts);
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splx(s);
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}
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splx(s);
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return;
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wrong_time:
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@ -550,23 +550,30 @@ int
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rtcin(reg)
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int reg;
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{
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int s;
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u_char val;
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s = splhigh();
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outb(IO_RTC, reg);
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inb(0x84);
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val = inb(IO_RTC + 1);
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inb(0x84);
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splx(s);
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return (val);
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}
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static __inline void
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writertc(u_char reg, u_char val)
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{
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int s;
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s = splhigh();
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inb(0x84);
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outb(IO_RTC, reg);
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inb(0x84);
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outb(IO_RTC + 1, val);
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inb(0x84); /* XXX work around wrong order in rtcin() */
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splx(s);
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}
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static __inline int
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@ -847,7 +854,11 @@ inittodr(time_t base)
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/* wait for time update to complete */
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/* If RTCSA_TUP is zero, we have at least 244us before next update */
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while (rtcin(RTC_STATUSA) & RTCSA_TUP);
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s = splhigh();
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while (rtcin(RTC_STATUSA) & RTCSA_TUP) {
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splx(s);
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s = splhigh();
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}
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days = 0;
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#ifdef USE_RTC_CENTURY
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@ -857,8 +868,10 @@ inittodr(time_t base)
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if (year < 1970)
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year += 100;
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#endif
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if (year < 1970)
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if (year < 1970) {
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splx(s);
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goto wrong_time;
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}
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month = readrtc(RTC_MONTH);
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for (m = 1; m < month; m++)
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days += daysinmonth[m-1];
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@ -880,12 +893,11 @@ inittodr(time_t base)
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y = time_second - sec;
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if (y <= -2 || y >= 2) {
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/* badly off, adjust it */
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s = splclock();
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ts.tv_sec = sec;
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ts.tv_nsec = 0;
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set_timecounter(&ts);
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splx(s);
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}
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splx(s);
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return;
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wrong_time:
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