Re: [PATCH] m68k: Remove read_persistent_clock()

From: Arnd Bergmann
Date: Fri Apr 20 2018 - 11:22:57 EST

On Thu, Apr 19, 2018 at 8:22 AM, Baolin Wang <> wrote:
> The read_persistent_clock() uses a timespec, which is not year 2038 safe
> on 32bit systems. Moreover on m68k architecture, we have implemented generic
> RTC drivers that can be used to compensate the system suspend time. So
> we can remove the obsolete read_persistent_clock().
> Signed-off-by: Baolin Wang <>

I'm not sure about this one: it's still possible to turn off
on M68KCLASSIC, and in that case we still need a read_persistent_clock64()
implementation. Or we use your patch but make CONFIG_RTC_DRV_GENERIC

See below for a version I did a while ago (but never submitted as I got


commit 13ddf5a33a195e9b7a7a6ed10481363b5259c1d4
Author: Arnd Bergmann <arnd@xxxxxxxx>
Date: Thu Jan 25 15:30:50 2018 +0100

m68k: use read_persistent_clock64 consistently

We have two ways of getting the current time from a platform at boot
or during suspend: either using read_persistent_clock() or the rtc
class operation. We never need both, so I'm hiding the
read_persistent_clock variant when the generic RTC is enabled.

Since read_persistent_clock() and mktime() are deprecated because of
the y2038 overflow of time_t, we should use the time64_t based
replacements here.

Finally, the dependency on CONFIG_ARCH_USES_GETTIMEOFFSET looks
completely bogus in this case, so let's remove that. It was
added in commit b13b3f51ff7b ("m68k: fix inclusion of
arch_gettimeoffset for non-MMU 68k classic CPU types") to deal
with arch_gettimeoffset(), which has since been removed from
this file and is unrelated to the RTC functions.

The rtc accessors are only used by classic machines, while
coldfire uses proper RTC drivers, so we can put the old
ifdef back around both functions.

Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>

diff --git a/arch/m68k/kernel/time.c b/arch/m68k/kernel/time.c
index 97dd4e26f234..edcf3855d8b0 100644
--- a/arch/m68k/kernel/time.c
+++ b/arch/m68k/kernel/time.c
@@ -71,7 +71,9 @@ static irqreturn_t timer_interrupt(int irq, void *dummy)

-void read_persistent_clock(struct timespec *ts)
+void read_persistent_clock64(struct timespec64 *ts)
struct rtc_time time;
ts->tv_sec = 0;
@@ -82,12 +84,13 @@ void read_persistent_clock(struct timespec *ts)

if ((time.tm_year += 1900) < 1970)
time.tm_year += 100;
- ts->tv_sec = mktime(time.tm_year, time.tm_mon, time.tm_mday,
+ ts->tv_sec = mktime64(time.tm_year, time.tm_mon, time.tm_mday,
time.tm_hour, time.tm_min, time.tm_sec);

static int rtc_generic_get_time(struct device *dev, struct rtc_time *tm)
mach_hwclk(0, tm);
@@ -145,8 +148,8 @@ static int __init rtc_init(void)

+#endif /* CONFIG M68KCLASSIC */

void __init time_init(void)