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

diff --git a/drivers/rtc/rtc-mc146818-lib.c b/drivers/rtc/rtc-mc146818-lib.c
index b20f4eb..15604b7 100644 (file)
--- a/drivers/rtc/rtc-mc146818-lib.c
+++ b/drivers/rtc/rtc-mc146818-lib.c
@@ -103,49 +103,20 @@ bool mc146818_does_rtc_work(void)
 }
 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 long flags;
-       unsigned int iter_count = 0;
-       unsigned char century = 0;
-       bool retry;
-
+#ifdef CONFIG_ACPI
+       unsigned char century;
+#endif
 #ifdef CONFIG_MACH_DECSTATION
        unsigned int real_year;
 #endif
+};
 
-again:
-       if (iter_count > 10) {
-               memset(time, 0, sizeof(*time));
-               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;
-       }
+static void mc146818_get_time_callback(unsigned char seconds, void *param_in)
+{
+       struct mc146818_get_time_callback_param *p = param_in;
 
        /*
         * 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
         * by the RTC when initially set to a non-zero value.
         */
-       time->tm_min = CMOS_READ(RTC_MINUTES);
-       time->tm_hour = CMOS_READ(RTC_HOURS);
-       time->tm_mday = CMOS_READ(RTC_DAY_OF_MONTH);
-       time->tm_mon = CMOS_READ(RTC_MONTH);
-       time->tm_year = CMOS_READ(RTC_YEAR);
+       p->time->tm_sec = seconds;
+       p->time->tm_min = CMOS_READ(RTC_MINUTES);
+       p->time->tm_hour = CMOS_READ(RTC_HOURS);
+       p->time->tm_mday = CMOS_READ(RTC_DAY_OF_MONTH);
+       p->time->tm_mon = CMOS_READ(RTC_MONTH);
+       p->time->tm_year = CMOS_READ(RTC_YEAR);
 #ifdef CONFIG_MACH_DECSTATION
-       real_year = CMOS_READ(RTC_DEC_YEAR);
+       p->real_year = CMOS_READ(RTC_DEC_YEAR);
 #endif
 #ifdef CONFIG_ACPI
        if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID &&
-           acpi_gbl_FADT.century)
-               century = CMOS_READ(acpi_gbl_FADT.century);
+           acpi_gbl_FADT.century) {
+               p->century = CMOS_READ(acpi_gbl_FADT.century);
+       } else {
+               p->century = 0;
+       }
 #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)
-               goto again;
+unsigned int mc146818_get_time(struct rtc_time *time)
+{
+       struct mc146818_get_time_callback_param p = {
+               .time = time
+       };
+
+       if (!mc146818_avoid_UIP(mc146818_get_time_callback, &p)) {
+               memset(time, 0, sizeof(*time));
+               return -EIO;
+       }
 
-       if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
+       if (!(p.ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
        {
                time->tm_sec = bcd2bin(time->tm_sec);
                time->tm_min = bcd2bin(time->tm_min);
@@ -193,15 +164,19 @@ again:
                time->tm_mday = bcd2bin(time->tm_mday);
                time->tm_mon = bcd2bin(time->tm_mon);
                time->tm_year = bcd2bin(time->tm_year);
-               century = bcd2bin(century);
+#ifdef CONFIG_ACPI
+               p.century = bcd2bin(p.century);
+#endif
        }
 
 #ifdef CONFIG_MACH_DECSTATION
-       time->tm_year += real_year - 72;
+       time->tm_year += p.real_year - 72;
 #endif
 
-       if (century > 20)
-               time->tm_year += (century - 19) * 100;
+#ifdef CONFIG_ACPI
+       if (p.century > 20)
+               time->tm_year += (p.century - 19) * 100;
+#endif
 
        /*
         * Account for differences between how the RTC uses the values