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Date: Sat, 30 Oct 2021 23:46:32 +0200
From: Mateusz Jończyk <mat.jonczyk@...pl>
To: linux-rtc@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: Mateusz Jończyk <mat.jonczyk@...pl>,
Alessandro Zummo <a.zummo@...ertech.it>,
Alexandre Belloni <alexandre.belloni@...tlin.com>
Subject: [PATCH v3 4/7] rtc-mc146818-lib: refactor mc146818_get_time
Refactor mc146818_get_time() to make use of mc146818_do_avoiding_UIP().
Signed-off-by: Mateusz Jończyk <mat.jonczyk@...pl>
Cc: Alessandro Zummo <a.zummo@...ertech.it>
Cc: Alexandre Belloni <alexandre.belloni@...tlin.com>
---
drivers/rtc/rtc-mc146818-lib.c | 111 +++++++++++++--------------------
1 file changed, 43 insertions(+), 68 deletions(-)
I'm sorry that the diff is quite difficult to read, but I was unable to
fix this easily.
diff --git a/drivers/rtc/rtc-mc146818-lib.c b/drivers/rtc/rtc-mc146818-lib.c
index 946ad43a512c..f3178244db37 100644
--- a/drivers/rtc/rtc-mc146818-lib.c
+++ b/drivers/rtc/rtc-mc146818-lib.c
@@ -102,50 +102,20 @@ 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) {
- pr_err_ratelimited("Unable to read current time from RTC\n");
- memset(time, 0xff, sizeof(*time));
- return 0;
- }
- 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 +123,40 @@ unsigned int mc146818_get_time(struct rtc_time *time)
* 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 (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
+ if (!mc146818_do_avoiding_UIP(mc146818_get_time_callback, &p)) {
+ pr_err_ratelimited("Unable to read current time from RTC\n");
+ memset(time, 0xff, sizeof(*time));
+ return 0;
+ }
+
+ 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 @@ unsigned int mc146818_get_time(struct rtc_time *time)
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
--
2.25.1
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