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authorFinn Thain <fthain@telegraphics.com.au>2018-04-23 11:02:57 +1000
committerGeert Uytterhoeven <geert@linux-m68k.org>2018-05-22 10:31:50 +0200
commitb65769fc013edb7c2e5fdcd91ea6124ad76168f5 (patch)
treeb6ad02cfbf7a81d1a4f339d0873fabb71b8b549e /arch/m68k/kernel
parent4eee57d68b8b2e6e0a6960c0bacf93448e4ae214 (diff)
downloadblackbird-op-linux-b65769fc013edb7c2e5fdcd91ea6124ad76168f5.tar.gz
blackbird-op-linux-b65769fc013edb7c2e5fdcd91ea6124ad76168f5.zip
m68k: Fix off-by-one calendar month
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>
Diffstat (limited to 'arch/m68k/kernel')
-rw-r--r--arch/m68k/kernel/time.c14
1 files changed, 7 insertions, 7 deletions
diff --git a/arch/m68k/kernel/time.c b/arch/m68k/kernel/time.c
index 97dd4e26f234..6b4389a6e8ea 100644
--- a/arch/m68k/kernel/time.c
+++ b/arch/m68k/kernel/time.c
@@ -74,17 +74,17 @@ static irqreturn_t timer_interrupt(int irq, void *dummy)
void read_persistent_clock(struct timespec *ts)
{
struct rtc_time time;
+
ts->tv_sec = 0;
ts->tv_nsec = 0;
- if (mach_hwclk) {
- mach_hwclk(0, &time);
+ if (!mach_hwclk)
+ return;
+
+ mach_hwclk(0, &time);
- if ((time.tm_year += 1900) < 1970)
- time.tm_year += 100;
- ts->tv_sec = mktime(time.tm_year, time.tm_mon, time.tm_mday,
- time.tm_hour, time.tm_min, time.tm_sec);
- }
+ ts->tv_sec = mktime(time.tm_year + 1900, time.tm_mon + 1, time.tm_mday,
+ time.tm_hour, time.tm_min, time.tm_sec);
}
#if defined(CONFIG_ARCH_USES_GETTIMEOFFSET) && IS_ENABLED(CONFIG_RTC_DRV_GENERIC)
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