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rtc: mc146818-lib: refactor mc146818_get_time 

Refactor mc146818_get_time() so that it uses mc146818_avoid_UIP().

Signed-off-by: Mateusz Jończyk <mat.jonczyk@o2.pl>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20211210200131.153887-7-mat.jonczyk@o2.pl
This commit is contained in:
Mateusz Jończyk 2021-12-10 21:01:28 +01:00 committed by Alexandre Belloni
parent ec5895c0f2
commit 2a61b0ac54
1 changed files with 42 additions and 67 deletions
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109
drivers/rtc/rtc-mc146818-lib.c
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@ -103,49 +103,20 @@ bool mc146818_does_rtc_work(void)
} }
EXPORT_SYMBOL_GPL(mc146818_does_rtc_work); EXPORT_SYMBOL_GPL(mc146818_does_rtc_work);
unsigned int mc146818_get_time(struct rtc_time *time) struct mc146818_get_time_callback_param {
{ struct rtc_time *time;
unsigned char ctrl; unsigned char ctrl;
unsigned long flags; #ifdef CONFIG_ACPI
unsigned int iter_count = 0; unsigned char century;
unsigned char century = 0; #endif
bool retry;
#ifdef CONFIG_MACH_DECSTATION #ifdef CONFIG_MACH_DECSTATION
unsigned int real_year; unsigned int real_year;
#endif #endif
};
again: static void mc146818_get_time_callback(unsigned char seconds, void *param_in)
if (iter_count > 10) { {
memset(time, 0, sizeof(*time)); struct mc146818_get_time_callback_param *p = param_in;
return -EIO;
}
iter_count++;
spin_lock_irqsave(&rtc_lock, flags);
/*
* Check whether there is an update in progress during which the
* readout is unspecified. The maximum update time is ~2ms. Poll
* every msec for completion.
*
* Store the second value before checking UIP so a long lasting NMI
* which happens to hit after the UIP check cannot make an update
* cycle invisible.
*/
time->tm_sec = CMOS_READ(RTC_SECONDS);
if (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP) {
spin_unlock_irqrestore(&rtc_lock, flags);
mdelay(1);
goto again;
}
/* Revalidate the above readout */
if (time->tm_sec != CMOS_READ(RTC_SECONDS)) {
spin_unlock_irqrestore(&rtc_lock, flags);
goto again;
}
/* /*
* Only the values that we read from the RTC are set. We leave * Only the values that we read from the RTC are set. We leave
@ -153,39 +124,39 @@ again:
* RTC has RTC_DAY_OF_WEEK, we ignore it, as it is only updated * RTC has RTC_DAY_OF_WEEK, we ignore it, as it is only updated
* by the RTC when initially set to a non-zero value. * by the RTC when initially set to a non-zero value.
*/ */
time->tm_min = CMOS_READ(RTC_MINUTES); p->time->tm_sec = seconds;
time->tm_hour = CMOS_READ(RTC_HOURS); p->time->tm_min = CMOS_READ(RTC_MINUTES);
time->tm_mday = CMOS_READ(RTC_DAY_OF_MONTH); p->time->tm_hour = CMOS_READ(RTC_HOURS);
time->tm_mon = CMOS_READ(RTC_MONTH); p->time->tm_mday = CMOS_READ(RTC_DAY_OF_MONTH);
time->tm_year = CMOS_READ(RTC_YEAR); p->time->tm_mon = CMOS_READ(RTC_MONTH);
p->time->tm_year = CMOS_READ(RTC_YEAR);
#ifdef CONFIG_MACH_DECSTATION #ifdef CONFIG_MACH_DECSTATION
real_year = CMOS_READ(RTC_DEC_YEAR); p->real_year = CMOS_READ(RTC_DEC_YEAR);
#endif #endif
#ifdef CONFIG_ACPI #ifdef CONFIG_ACPI
if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID && if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID &&
acpi_gbl_FADT.century) acpi_gbl_FADT.century) {
century = CMOS_READ(acpi_gbl_FADT.century); p->century = CMOS_READ(acpi_gbl_FADT.century);
} else {
p->century = 0;
}
#endif #endif
ctrl = CMOS_READ(RTC_CONTROL);
/*
* Check for the UIP bit again. If it is set now then
* the above values may contain garbage.
*/
retry = CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP;
/*
* A NMI might have interrupted the above sequence so check whether
* the seconds value has changed which indicates that the NMI took
* longer than the UIP bit was set. Unlikely, but possible and
* there is also virt...
*/
retry |= time->tm_sec != CMOS_READ(RTC_SECONDS);
spin_unlock_irqrestore(&rtc_lock, flags); p->ctrl = CMOS_READ(RTC_CONTROL);
}
if (retry) unsigned int mc146818_get_time(struct rtc_time *time)
goto again; {
struct mc146818_get_time_callback_param p = {
.time = time
};
if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD) if (!mc146818_avoid_UIP(mc146818_get_time_callback, &p)) {
memset(time, 0, sizeof(*time));
return -EIO;
}
if (!(p.ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
{ {
time->tm_sec = bcd2bin(time->tm_sec); time->tm_sec = bcd2bin(time->tm_sec);
time->tm_min = bcd2bin(time->tm_min); time->tm_min = bcd2bin(time->tm_min);
@ -193,15 +164,19 @@ again:
time->tm_mday = bcd2bin(time->tm_mday); time->tm_mday = bcd2bin(time->tm_mday);
time->tm_mon = bcd2bin(time->tm_mon); time->tm_mon = bcd2bin(time->tm_mon);
time->tm_year = bcd2bin(time->tm_year); time->tm_year = bcd2bin(time->tm_year);
century = bcd2bin(century); #ifdef CONFIG_ACPI
p.century = bcd2bin(p.century);
#endif
} }
#ifdef CONFIG_MACH_DECSTATION #ifdef CONFIG_MACH_DECSTATION
time->tm_year += real_year - 72; time->tm_year += p.real_year - 72;
#endif #endif
if (century > 20) #ifdef CONFIG_ACPI
time->tm_year += (century - 19) * 100; if (p.century > 20)
time->tm_year += (p.century - 19) * 100;
#endif
/* /*
* Account for differences between how the RTC uses the values * Account for differences between how the RTC uses the values