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mips/malta,loongson2ef: use generic mc146818_get_time function

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mc146818_get_cmos_time() is now mostly equivalent to mc146818_get_time()
from drivers/rtc/rtc-mc146818-lib.c, with the latter using a more
advanced algorithm (which checks the UIP bit in the CMOS). The Malta
and Loongson2ef platforms, the only users of mc146818_get_cmos_time()
have RTC devices that should be MC146818 compatible.

So, rewrite mc146818_get_cmos_time() in a way that uses
mc146818_get_time() and add CONFIG_RTC_MC146818_LIB as a dependency of
CONFIG_MIPS_MALTA and CONFIG_CPU_LOONGSON2EF.

The should be safe as:

- malta_defconfig already uses a standard RTC CMOS driver
  (CONFIG_RTC_DRV_CMOS=y). The Malta board has an Intel 82371EB (PIIX4E)
  south bridge with the CMOS RTC, so should work correctly with the
  modification,

- Loongson2e and 2f apparently use the VIA686B south bridge and the AMD
  CS5536 south bridge respectively (at least according to Kconfig). I
  have checked datasheets of both and these appear to be MC146818
  software compatible.

Signed-off-by: Mateusz Jończyk <mat.jonczyk@o2.pl>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
This commit is contained in:
Mateusz Jończyk 2025-07-13 12:04:34 +02:00 committed by Thomas Bogendoerfer
parent 6e68ee3475
commit 01557e349c
2 changed files with 9 additions and 27 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/mips/Kconfig
View File

@ -563,6 +563,7 @@ config MIPS_MALTA
select MIPS_L1_CACHE_SHIFT_6
select MIPS_MSC
select PCI_GT64XXX_PCI0
select RTC_MC146818_LIB
select SMP_UP if SMP
select SWAP_IO_SPACE
select SYS_HAS_CPU_MIPS32_R1
@ -1837,6 +1838,7 @@ config CPU_LOONGSON2EF
select CPU_SUPPORTS_64BIT_KERNEL
select CPU_SUPPORTS_HIGHMEM
select CPU_SUPPORTS_HUGEPAGES
select RTC_MC146818_LIB
config CPU_LOONGSON32
bool

34
arch/mips/include/asm/mc146818-time.h
View File

@ -8,41 +8,21 @@
#ifndef __ASM_MC146818_TIME_H
#define __ASM_MC146818_TIME_H
#include <linux/bcd.h>
#include <linux/mc146818rtc.h>
#include <linux/time.h>
#ifdef CONFIG_RTC_MC146818_LIB
static inline time64_t mc146818_get_cmos_time(void)
{
unsigned int year, mon, day, hour, min, sec;
unsigned long flags;
struct rtc_time tm;
spin_lock_irqsave(&rtc_lock, flags);
do {
sec = CMOS_READ(RTC_SECONDS);
min = CMOS_READ(RTC_MINUTES);
hour = CMOS_READ(RTC_HOURS);
day = CMOS_READ(RTC_DAY_OF_MONTH);
mon = CMOS_READ(RTC_MONTH);
year = CMOS_READ(RTC_YEAR);
} while (sec != CMOS_READ(RTC_SECONDS));
if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
sec = bcd2bin(sec);
min = bcd2bin(min);
hour = bcd2bin(hour);
day = bcd2bin(day);
mon = bcd2bin(mon);
year = bcd2bin(year);
if (mc146818_get_time(&tm, 1000)) {
pr_err("Unable to read current time from RTC\n");
return 0;
}
spin_unlock_irqrestore(&rtc_lock, flags);
if (year < 70)
year += 2000;
else
year += 1900;
return mktime64(year, mon, day, hour, min, sec);
return rtc_tm_to_time64(&tm);
}
#endif /* CONFIG_RTC_MC146818_LIB */
#endif /* __ASM_MC146818_TIME_H */