From: "Mateusz Jończyk" <mat.jonczyk@o2.pl>
To: Jiaxun Yang <jiaxun.yang@flygoat.com>,
Huacai Chen <chenhuacai@kernel.org>,
Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: "Alexandre Belloni" <alexandre.belloni@bootlin.com>,
linux-mips@vger.kernel.org, linux-rtc@vger.kernel.org,
"Mateusz Jończyk" <mat.jonczyk@o2.pl>
Subject: [PATCH 1/4] mips: remove unused function mc146818_set_rtc_mmss
Date: Sun, 13 Jul 2025 12:04:31 +0200 [thread overview]
Message-ID: <20250713100434.699843-2-mat.jonczyk@o2.pl> (raw)
In-Reply-To: <20250713100434.699843-1-mat.jonczyk@o2.pl>
I have checked carefully: this function is unused, so remove it.
The last caller appears to have been removed in 2007 in
commit 4b550488f894 ("[MIPS] Deforest the function pointer jungle in the time code.")
mc146818-time.h is included only in three files:
- arch/mips/mti-malta/malta-time.c
- arch/mips/loongson64/numa.c
- arch/mips/loongson2ef/common/time.c
Also, remove unused macros USEC_AFTER/USEC_BEFORE.
Signed-off-by: Mateusz Jończyk <mat.jonczyk@o2.pl>
---
arch/mips/include/asm/mc146818-time.h | 74 ---------------------------
1 file changed, 74 deletions(-)
diff --git a/arch/mips/include/asm/mc146818-time.h b/arch/mips/include/asm/mc146818-time.h
index cbf5cec345f1..07bf30bee792 100644
--- a/arch/mips/include/asm/mc146818-time.h
+++ b/arch/mips/include/asm/mc146818-time.h
@@ -12,80 +12,6 @@
#include <linux/mc146818rtc.h>
#include <linux/time.h>
-/*
- * For check timing call set_rtc_mmss() 500ms; used in timer interrupt.
- */
-#define USEC_AFTER 500000
-#define USEC_BEFORE 500000
-
-/*
- * In order to set the CMOS clock precisely, set_rtc_mmss has to be
- * called 500 ms after the second nowtime has started, because when
- * nowtime is written into the registers of the CMOS clock, it will
- * jump to the next second precisely 500 ms later. Check the Motorola
- * MC146818A or Dallas DS12887 data sheet for details.
- *
- * BUG: This routine does not handle hour overflow properly; it just
- * sets the minutes. Usually you'll only notice that after reboot!
- */
-static inline int mc146818_set_rtc_mmss(unsigned long nowtime)
-{
- int real_seconds, real_minutes, cmos_minutes;
- unsigned char save_control, save_freq_select;
- int retval = 0;
- unsigned long flags;
-
- spin_lock_irqsave(&rtc_lock, flags);
- save_control = CMOS_READ(RTC_CONTROL); /* tell the clock it's being set */
- CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL);
-
- save_freq_select = CMOS_READ(RTC_FREQ_SELECT); /* stop and reset prescaler */
- CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
-
- cmos_minutes = CMOS_READ(RTC_MINUTES);
- if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
- cmos_minutes = bcd2bin(cmos_minutes);
-
- /*
- * since we're only adjusting minutes and seconds,
- * don't interfere with hour overflow. This avoids
- * messing with unknown time zones but requires your
- * RTC not to be off by more than 15 minutes
- */
- real_seconds = nowtime % 60;
- real_minutes = nowtime / 60;
- if (((abs(real_minutes - cmos_minutes) + 15)/30) & 1)
- real_minutes += 30; /* correct for half hour time zone */
- real_minutes %= 60;
-
- if (abs(real_minutes - cmos_minutes) < 30) {
- if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
- real_seconds = bin2bcd(real_seconds);
- real_minutes = bin2bcd(real_minutes);
- }
- CMOS_WRITE(real_seconds, RTC_SECONDS);
- CMOS_WRITE(real_minutes, RTC_MINUTES);
- } else {
- printk_once(KERN_NOTICE
- "set_rtc_mmss: can't update from %d to %d\n",
- cmos_minutes, real_minutes);
- retval = -1;
- }
-
- /* The following flags have to be released exactly in this order,
- * otherwise the DS12887 (popular MC146818A clone with integrated
- * battery and quartz) will not reset the oscillator and will not
- * update precisely 500 ms later. You won't find this mentioned in
- * the Dallas Semiconductor data sheets, but who believes data
- * sheets anyway ... -- Markus Kuhn
- */
- CMOS_WRITE(save_control, RTC_CONTROL);
- CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
- spin_unlock_irqrestore(&rtc_lock, flags);
-
- return retval;
-}
-
static inline time64_t mc146818_get_cmos_time(void)
{
unsigned int year, mon, day, hour, min, sec;
--
2.25.1
next prev parent reply other threads:[~2025-07-13 10:05 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-07-13 10:04 [PATCH 0/4] mips: CMOS RTC refactoring Mateusz Jończyk
2025-07-13 10:04 ` Mateusz Jończyk [this message]
2025-07-13 10:04 ` [PATCH 2/4] mips/mach-rm: remove custom mc146818rtc.h file Mateusz Jończyk
2025-07-13 10:04 ` [PATCH 3/4] mips: remove redundant macro mc146818_decode_year Mateusz Jończyk
2025-07-13 10:04 ` [PATCH 4/4] mips/malta,loongson2ef: use generic mc146818_get_time function Mateusz Jończyk
2025-07-16 18:07 ` [PATCH 0/4] mips: CMOS RTC refactoring Thomas Bogendoerfer
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