From b65769fc013edb7c2e5fdcd91ea6124ad76168f5 Mon Sep 17 00:00:00 2001 From: Finn Thain Date: Mon, 23 Apr 2018 11:02:57 +1000 Subject: 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 Signed-off-by: Finn Thain Reviewed-by: Arnd Bergmann Signed-off-by: Geert Uytterhoeven --- arch/m68k/kernel/time.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) (limited to 'arch/m68k/kernel') 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) -- cgit v1.2.1