From mboxrd@z Thu Jan 1 00:00:00 1970 From: Martin Schwidefsky Subject: [patch 3/3] use direct ktime path for s390 clockevent device Date: Tue, 23 Aug 2011 15:29:44 +0200 Message-ID: <20110823133143.153017933@de.ibm.com> References: <20110823132941.744407154@de.ibm.com> Return-path: Content-Disposition: inline; filename=clockevent-feat-ktime-s390.diff Sender: linux-arch-owner@vger.kernel.org List-Archive: List-Post: To: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, Thomas Gleixner , Ingo Molnar , john stultz Cc: Martin Schwidefsky List-ID: From: Martin Schwidefsky The clock comparator on s390 uses the same format as the TOD clock. If the value in the clock comparator is smaller than the current TOD value an interrupt is pending. Use the CLOCK_EVT_FEAT_KTIME feature to get the unmodified ktime of the next clockevent expiration and use it to program the clock comparator without querying the TOD clock. Signed-off-by: Martin Schwidefsky --- arch/s390/kernel/time.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) Index: linux-clockevents/arch/s390/kernel/time.c =================================================================== --- linux-clockevents.orig/arch/s390/kernel/time.c 2011-05-31 12:30:48.082228487 +0200 +++ linux-clockevents/arch/s390/kernel/time.c 2011-08-23 15:16:03.219640374 +0200 @@ -109,10 +109,14 @@ set_clock_comparator(S390_lowcore.clock_comparator); } -static int s390_next_event(unsigned long delta, +static int s390_next_ktime(ktime_t expires, struct clock_event_device *evt) { - S390_lowcore.clock_comparator = get_clock() + delta; + s64 nsecs; + + nsecs = ktime_to_ns(ktime_sub(expires, ktime_get_monotonic_offset())); + do_div(nsecs, 125); + S390_lowcore.clock_comparator = TOD_UNIX_EPOCH + (nsecs << 9); set_clock_comparator(S390_lowcore.clock_comparator); return 0; } @@ -137,14 +141,15 @@ cpu = smp_processor_id(); cd = &per_cpu(comparators, cpu); cd->name = "comparator"; - cd->features = CLOCK_EVT_FEAT_ONESHOT; + cd->features = CLOCK_EVT_FEAT_ONESHOT | + CLOCK_EVT_FEAT_KTIME; cd->mult = 16777; cd->shift = 12; cd->min_delta_ns = 1; cd->max_delta_ns = LONG_MAX; cd->rating = 400; cd->cpumask = cpumask_of(cpu); - cd->set_next_event = s390_next_event; + cd->set_next_ktime = s390_next_ktime; cd->set_mode = s390_set_mode; clockevents_register_device(cd);