Merge branch 'x86-cache-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git...

[sfrench/cifs-2.6.git] / drivers / rtc / systohc.c

diff --git a/drivers/rtc/systohc.c b/drivers/rtc/systohc.c
index b4a68ffcd06bb876231f2893de69f30a8fe854d9..0c177647ea6c71c00d5df725beea9b83c7e4e79e 100644 (file)
--- a/drivers/rtc/systohc.c
+++ b/drivers/rtc/systohc.c
@@ -10,6 +10,7 @@
 /**
  * rtc_set_ntp_time - Save NTP synchronized time to the RTC
  * @now: Current time of day
+ * @target_nsec: pointer for desired now->tv_nsec value
  *
  * Replacement for the NTP platform function update_persistent_clock64
  * that stores time for later retrieval by rtc_hctosys.
@@ -18,30 +19,52 @@
  * possible at all, and various other -errno for specific temporary failure
  * cases.
  *
+ * -EPROTO is returned if now.tv_nsec is not close enough to *target_nsec.
+ (
  * If temporary failure is indicated the caller should try again 'soon'
  */
-int rtc_set_ntp_time(struct timespec64 now)
+int rtc_set_ntp_time(struct timespec64 now, unsigned long *target_nsec)
 {
        struct rtc_device *rtc;
        struct rtc_time tm;
+       struct timespec64 to_set;
        int err = -ENODEV;
-
-       if (now.tv_nsec < (NSEC_PER_SEC >> 1))
-               rtc_time64_to_tm(now.tv_sec, &tm);
-       else
-               rtc_time64_to_tm(now.tv_sec + 1, &tm);
+       bool ok;
 
        rtc = rtc_class_open(CONFIG_RTC_SYSTOHC_DEVICE);
-       if (rtc) {
-               /* rtc_hctosys exclusively uses UTC, so we call set_time here,
-                * not set_mmss. */
-               if (rtc->ops &&
-                   (rtc->ops->set_time ||
-                    rtc->ops->set_mmss64 ||
-                    rtc->ops->set_mmss))
-                       err = rtc_set_time(rtc, &tm);
-               rtc_class_close(rtc);
+       if (!rtc)
+               goto out_err;
+
+       if (!rtc->ops || (!rtc->ops->set_time && !rtc->ops->set_mmss64 &&
+                         !rtc->ops->set_mmss))
+               goto out_close;
+
+       /* Compute the value of tv_nsec we require the caller to supply in
+        * now.tv_nsec.  This is the value such that (now +
+        * set_offset_nsec).tv_nsec == 0.
+        */
+       set_normalized_timespec64(&to_set, 0, -rtc->set_offset_nsec);
+       *target_nsec = to_set.tv_nsec;
+
+       /* The ntp code must call this with the correct value in tv_nsec, if
+        * it does not we update target_nsec and return EPROTO to make the ntp
+        * code try again later.
+        */
+       ok = rtc_tv_nsec_ok(rtc->set_offset_nsec, &to_set, &now);
+       if (!ok) {
+               err = -EPROTO;
+               goto out_close;
        }
 
+       rtc_time64_to_tm(to_set.tv_sec, &tm);
+
+       /* rtc_hctosys exclusively uses UTC, so we call set_time here, not
+        * set_mmss.
+        */
+       err = rtc_set_time(rtc, &tm);
+
+out_close:
+       rtc_class_close(rtc);
+out_err:
        return err;
 }