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m68k: Fix off-by-one calendar month

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This fixes a bug in read_persistent_clock() which causes the system
clock to lag the Real Time Clock by one month. The problem was noticed
on a Mac, but theoretically it must also affect Atari, BVME6000 and Q40.

The tm_mon value in the struct rtc_time passed to mach_hwclk() is
zero-based, and atari_mste_hwclk(), atari_tt_hwclk(), bvme6000_hwclk(),
mac_hwclk() and q40_hwclk() all make this adjustment. Unfortunately,
dn_dummy_hwclk(), mvme147_hwclk(), mvme16x_hwclk(), sun3_hwclk() and
sun3x_hwclk() fail to decrement tm_mon.  Also m68328_hwclk() assumes
a one-based tm_mon.

Bring these platforms into line and fix read_persistent_clock() so it
works correctly on all m68k platforms.

The datasheets for the RTC devices found on the affected platforms
all confirm that the year is stored as a value in the range 0-99 and
the month is stored as a value in the range 1-12. Please refer to the
datasheets for MC146818 (Apollo), DS1643 (MVME), ICM7170 (Sun 3)
and M48T02 (Sun 3x).

Reported-by: Stan Johnson <userm57@yahoo.com>
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
This commit is contained in:
Finn Thain
2018-04-23 11:02:57 +10:00
committed by Geert Uytterhoeven
parent 4eee57d68b
commit b65769fc01
7 changed files with 31 additions and 19 deletions
Download Patch File Download Diff File Expand all files Collapse all files

8
arch/m68k/apollo/config.c
View File

@@ -221,8 +221,10 @@ int dn_dummy_hwclk(int op, struct rtc_time *t) {
t->tm_hour=rtc->hours;
t->tm_mday=rtc->day_of_month;
t->tm_wday=rtc->day_of_week;
t->tm_mon=rtc->month;
t->tm_mon = rtc->month - 1;
t->tm_year=rtc->year;
if (t->tm_year < 70)
t->tm_year += 100;
} else {
rtc->second=t->tm_sec;
rtc->minute=t->tm_min;
@@ -230,8 +232,8 @@ int dn_dummy_hwclk(int op, struct rtc_time *t) {
rtc->day_of_month=t->tm_mday;
if(t->tm_wday!=-1)
rtc->day_of_week=t->tm_wday;
rtc->month=t->tm_mon;
rtc->year=t->tm_year;
rtc->month = t->tm_mon + 1;
rtc->year = t->tm_year % 100;
}
return 0;