MIPS: Convert update_persistent_clock() to update_persistent_clock64()

Since struct timespec is not y2038 safe on 32bit machines, this patch
converts update_persistent_clock() to update_persistent_clock64() using
struct timespec64.

The rtc_mips_set_time() and rtc_mips_set_mmss() interfaces were using
'unsigned long' type that is not y2038 safe on 32bit machines, moreover
there is only one platform implementing rtc_mips_set_time() and two
platforms implementing rtc_mips_set_mmss(), so we can just make them each
implement update_persistent_clock64() directly, to get that helper out
of the common mips code by removing rtc_mips_set_time() and
rtc_mips_set_mmss() interfaces.

Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Huacai Chen <chenhc@lemote.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@linux-mips.org
Signed-off-by: James Hogan <jhogan@kernel.org>

arch/mips/dec/time.c

@@ -59,14 +59,15 @@ void read_persistent_clock64(struct timespec64 *ts)
 }
 
 /*
- * In order to set the CMOS clock precisely, rtc_mips_set_mmss has to
+ * In order to set the CMOS clock precisely, update_persistent_clock64 has to
  * be called 500 ms after the second nowtime has started, because when
  * nowtime is written into the registers of the CMOS clock, it will
  * jump to the next second precisely 500 ms later.  Check the Dallas
  * DS1287 data sheet for details.
  */
-int rtc_mips_set_mmss(unsigned long nowtime)
+int update_persistent_clock64(struct timespec64 now)
 {
+	time64_t nowtime = now.tv_sec;
 	int retval = 0;
 	int real_seconds, real_minutes, cmos_minutes;
 	unsigned char save_control, save_freq_select;
@@ -91,8 +92,7 @@ int rtc_mips_set_mmss(unsigned long nowtime)
 	 * messing with unknown time zones but requires your
 	 * RTC not to be off by more than 15 minutes
 	 */
-	real_seconds = nowtime % 60;
-	real_minutes = nowtime / 60;
+	real_minutes = div_s64_rem(nowtime, 60, &real_seconds);
 	if (((abs(real_minutes - cmos_minutes) + 15) / 30) & 1)
 		real_minutes += 30;	/* correct for half hour time zone */
 	real_minutes %= 60;

arch/mips/include/asm/time.h

@@ -21,15 +21,6 @@
 
 extern spinlock_t rtc_lock;
 
-/*
- * RTC ops.  By default, they point to weak no-op RTC functions.
- *	rtc_mips_set_time - reverse the above translation and set time to RTC.
- *	rtc_mips_set_mmss - similar to rtc_set_time, but only min and sec need
- *			to be set.  Used by RTC sync-up.
- */
-extern int rtc_mips_set_time(unsigned long);
-extern int rtc_mips_set_mmss(unsigned long);
-
 /*
  * board specific routines required by time_init().
  */

arch/mips/kernel/time.c

@@ -34,21 +34,6 @@
 DEFINE_SPINLOCK(rtc_lock);
 EXPORT_SYMBOL(rtc_lock);
 
-int __weak rtc_mips_set_time(unsigned long sec)
-{
-	return -ENODEV;
-}
-
-int __weak rtc_mips_set_mmss(unsigned long nowtime)
-{
-	return rtc_mips_set_time(nowtime);
-}
-
-int update_persistent_clock(struct timespec now)
-{
-	return rtc_mips_set_mmss(now.tv_sec);
-}
-
 static int null_perf_irq(void)
 {
 	return 0;

arch/mips/lasat/ds1603.c

@@ -152,14 +152,19 @@ void read_persistent_clock64(struct timespec64 *ts)
 	ts->tv_nsec = 0;
 }
 
-int rtc_mips_set_mmss(unsigned long time)
+int update_persistent_clock64(struct timespec64 now)
 {
+	time64_t time = now.tv_sec;
 	unsigned long flags;
 
 	spin_lock_irqsave(&rtc_lock, flags);
 	rtc_init_op();
 	rtc_write_byte(SET_TIME_CMD);
-	rtc_write_word(time);
+	/*
+	 * Due to the hardware limitation, we cast to 'unsigned long' type,
+	 * so it will overflow in year 2106 on 32-bit machine.
+	 */
+	rtc_write_word((unsigned long)time);
 	rtc_end_op();
 	spin_unlock_irqrestore(&rtc_lock, flags);
 

arch/mips/lasat/sysctl.c

@@ -73,8 +73,16 @@ int proc_dolasatrtc(struct ctl_table *table, int write,
 	if (r)
 		return r;
 
-	if (write)
-		rtc_mips_set_mmss(rtctmp);
+	if (write) {
+		/*
+		 * Due to the RTC hardware limitation, we can not actually
+		 * use the full 64-bit range here.
+		 */
+		ts.tv_sec = rtctmp;
+		ts.tv_nsec = 0;
+
+		update_persistent_clock64(ts);
+	}
 
 	return 0;
 }

arch/mips/sibyte/swarm/rtc_m41t81.c

@@ -141,13 +141,13 @@ static int m41t81_write(uint8_t addr, int b)
 	return 0;
 }
 
-int m41t81_set_time(unsigned long t)
+int m41t81_set_time(time64_t t)
 {
 	struct rtc_time tm;
 	unsigned long flags;
 
 	/* Note we don't care about the century */
-	rtc_time_to_tm(t, &tm);
+	rtc_time64_to_tm(t, &tm);
 
 	/*
 	 * Note the write order matters as it ensures the correctness.

arch/mips/sibyte/swarm/rtc_xicor1241.c

@@ -109,13 +109,13 @@ static int xicor_write(uint8_t addr, int b)
 	}
 }
 
-int xicor_set_time(unsigned long t)
+int xicor_set_time(time64_t t)
 {
 	struct rtc_time tm;
 	int tmp;
 	unsigned long flags;
 
-	rtc_time_to_tm(t, &tm);
+	rtc_time64_to_tm(t, &tm);
 	tm.tm_year += 1900;
 
 	spin_lock_irqsave(&rtc_lock, flags);

arch/mips/sibyte/swarm/setup.c

@@ -57,11 +57,11 @@ extern void sb1250_setup(void);
 #endif
 
 extern int xicor_probe(void);
-extern int xicor_set_time(unsigned long);
+extern int xicor_set_time(time64_t);
 extern time64_t xicor_get_time(void);
 
 extern int m41t81_probe(void);
-extern int m41t81_set_time(unsigned long);
+extern int m41t81_set_time(time64_t);
 extern time64_t m41t81_get_time(void);
 
 const char *get_system_type(void)
@@ -109,8 +109,10 @@ void read_persistent_clock64(struct timespec64 *ts)
 	ts->tv_nsec = 0;
 }
 
-int rtc_mips_set_time(unsigned long sec)
+int update_persistent_clock64(struct timespec64 now)
 {
+	time64_t sec = now.tv_sec;
+
 	switch (swarm_rtc_type) {
 	case RTC_XICOR:
 		return xicor_set_time(sec);