Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull timer updates from Thomas Gleixner:
 "Yet another big pile of changes:

   - More year 2038 work from Arnd slowly reaching the point where we
     need to think about the syscalls themself.

   - A new timer function which allows to conditionally (re)arm a timer
     only when it's either not running or the new expiry time is sooner
     than the armed expiry time. This allows to use a single timer for
     multiple timeout requirements w/o caring about the first expiry
     time at the call site.

   - A new NMI safe accessor to clock real time for the printk timestamp
     work. Can be used by tracing, perf as well if required.

   - A large number of timer setup conversions from Kees which got
     collected here because either maintainers requested so or they
     simply got ignored. As Kees pointed out already there are a few
     trivial merge conflicts and some redundant commits which was
     unavoidable due to the size of this conversion effort.

   - Avoid a redundant iteration in the timer wheel softirq processing.

   - Provide a mechanism to treat RTC implementations depending on their
     hardware properties, i.e. don't inflict the write at the 0.5
     seconds boundary which originates from the PC CMOS RTC to all RTCs.
     No functional change as drivers need to be updated separately.

   - The usual small updates to core code clocksource drivers. Nothing
     really exciting"

* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (111 commits)
  timers: Add a function to start/reduce a timer
  pstore: Use ktime_get_real_fast_ns() instead of __getnstimeofday()
  timer: Prepare to change all DEFINE_TIMER() callbacks
  netfilter: ipvs: Convert timers to use timer_setup()
  scsi: qla2xxx: Convert timers to use timer_setup()
  block/aoe: discover_timer: Convert timers to use timer_setup()
  ide: Convert timers to use timer_setup()
  drbd: Convert timers to use timer_setup()
  mailbox: Convert timers to use timer_setup()
  crypto: Convert timers to use timer_setup()
  drivers/pcmcia: omap1: Fix error in automated timer conversion
  ARM: footbridge: Fix typo in timer conversion
  drivers/sgi-xp: Convert timers to use timer_setup()
  drivers/pcmcia: Convert timers to use timer_setup()
  drivers/memstick: Convert timers to use timer_setup()
  drivers/macintosh: Convert timers to use timer_setup()
  hwrng/xgene-rng: Convert timers to use timer_setup()
  auxdisplay: Convert timers to use timer_setup()
  sparc/led: Convert timers to use timer_setup()
  mips: ip22/32: Convert timers to use timer_setup()
  ...

1 files changed, 42 insertions, 1 deletions

diff --git a/include/linux/rtc.h b/include/linux/rtc.h
index f6d7ee98d93c..41319a2e409b 100644
--- a/include/linux/rtc.h
+++ b/include/linux/rtc.h
@@ -136,6 +136,14 @@ struct rtc_device {
         /* Some hardware can't support UIE mode */
         int uie_unsupported;
 
+        /* Number of nsec it takes to set the RTC clock. This influences when
+         * the set ops are called. An offset:
+         *   - of 0.5 s will call RTC set for wall clock time 10.0 s at 9.5 s
+         *   - of 1.5 s will call RTC set for wall clock time 10.0 s at 8.5 s
+         *   - of -0.5 s will call RTC set for wall clock time 10.0 s at 10.5 s
+         */
+        long set_offset_nsec;
+
         bool registered;
 
         struct nvmem_config *nvmem_config;
@@ -173,7 +181,7 @@ extern void devm_rtc_device_unregister(struct device *dev,
 
 extern int rtc_read_time(struct rtc_device *rtc, struct rtc_time *tm);
 extern int rtc_set_time(struct rtc_device *rtc, struct rtc_time *tm);
-extern int rtc_set_ntp_time(struct timespec64 now);
+extern int rtc_set_ntp_time(struct timespec64 now, unsigned long *target_nsec);
 int __rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm);
 extern int rtc_read_alarm(struct rtc_device *rtc,
                         struct rtc_wkalrm *alrm);
@@ -222,6 +230,39 @@ static inline bool is_leap_year(unsigned int year)
         return (!(year % 4) && (year % 100)) || !(year % 400);
 }
 
+/* Determine if we can call to driver to set the time. Drivers can only be
+ * called to set a second aligned time value, and the field set_offset_nsec
+ * specifies how far away from the second aligned time to call the driver.
+ *
+ * This also computes 'to_set' which is the time we are trying to set, and has
+ * a zero in tv_nsecs, such that:
+ *    to_set - set_delay_nsec == now +/- FUZZ
+ *
+ */
+static inline bool rtc_tv_nsec_ok(s64 set_offset_nsec,
+                                  struct timespec64 *to_set,
+                                  const struct timespec64 *now)
+{
+        /* Allowed error in tv_nsec, arbitarily set to 5 jiffies in ns. */
+        const unsigned long TIME_SET_NSEC_FUZZ = TICK_NSEC * 5;
+        struct timespec64 delay = {.tv_sec = 0,
+                                   .tv_nsec = set_offset_nsec};
+
+        *to_set = timespec64_add(*now, delay);
+
+        if (to_set->tv_nsec < TIME_SET_NSEC_FUZZ) {
+                to_set->tv_nsec = 0;
+                return true;
+        }
+
+        if (to_set->tv_nsec > NSEC_PER_SEC - TIME_SET_NSEC_FUZZ) {
+                to_set->tv_sec++;
+                to_set->tv_nsec = 0;
+                return true;
+        }
+        return false;
+}
+
 #define rtc_register_device(device) \
         __rtc_register_device(THIS_MODULE, device)