Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758526AbZA2EGw (ORCPT ); Wed, 28 Jan 2009 23:06:52 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753983AbZA2EGm (ORCPT ); Wed, 28 Jan 2009 23:06:42 -0500 Received: from e5.ny.us.ibm.com ([32.97.182.145]:35237 "EHLO e5.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751069AbZA2EGl (ORCPT ); Wed, 28 Jan 2009 23:06:41 -0500 Subject: [RFC][PATCH 1/10] Create arch_gettimeoffset infrastructure for use in the generic timekeeping core. From: john stultz To: lkml Cc: rmk+lkml@arm.linux.org.uk, cooloney@kernel.org, starvik@axis.com, takata@linux-m32r.org, geert@linux-m68k.org, Roman Zippel , lethal@linux-sh.org, Magnus Damm , wli@holomorphy.com, chris@zankel.net, Thomas Gleixner In-Reply-To: <1233201926.6895.25.camel@localhost.localdomain> References: <1233201926.6895.25.camel@localhost.localdomain> Content-Type: text/plain Date: Wed, 28 Jan 2009 20:06:35 -0800 Message-Id: <1233201995.6895.27.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.22.3.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2632 Lines: 68 Some arches don't supply their own clocksource. This is mainly the case in architectures that get their inter-tick times by reading the counter on their interval timer. Since these timers wrap every tick, they're not really useful as clocksources. Wrapping them to act like one is possible but not very efficient. So we provide a callout these arches can implement for use with the jiffies clocksource to provide finer then tick granular time. Signed-off-by: John Stultz diff --git a/include/linux/time.h b/include/linux/time.h index fbbd2a1..4768f16 100644 --- a/include/linux/time.h +++ b/include/linux/time.h @@ -113,6 +113,21 @@ struct timespec current_kernel_time(void); #define CURRENT_TIME (current_kernel_time()) #define CURRENT_TIME_SEC ((struct timespec) { get_seconds(), 0 }) +/* Some architectures do not supply their own clocksource. + * This is mainly the case in architectures that get their + * inter-tick times by reading the counter on their interval + * timer. Since these timers wrap every tick, they're not really + * useful as clocksources. Wrapping them to act like one is possible + * but not very efficient. So we provide a callout these arches + * can implement for use with the jiffies clocksource to provide + * finer then tick granular time. + */ +#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET +extern u32 arch_gettimeoffset(void); +#else +#define arch_gettimeoffset() (0) +#endif + extern void do_gettimeofday(struct timeval *tv); extern int do_settimeofday(struct timespec *tv); extern int do_sys_settimeofday(struct timespec *tv, struct timezone *tz); diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 900f1b6..45d777f 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -77,6 +77,10 @@ static void clocksource_forward_now(void) clock->cycle_last = cycle_now; nsec = cyc2ns(clock, cycle_delta); + + /* If arch requires, add in gettimeoffset() */ + nsec += arch_gettimeoffset(); + timespec_add_ns(&xtime, nsec); nsec = ((s64)cycle_delta * clock->mult_orig) >> clock->shift; @@ -111,6 +115,9 @@ void getnstimeofday(struct timespec *ts) /* convert to nanoseconds: */ nsecs = cyc2ns(clock, cycle_delta); + /* If arch requires, add in gettimeoffset() */ + nsecs += arch_gettimeoffset(); + } while (read_seqretry(&xtime_lock, seq)); timespec_add_ns(ts, nsecs); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/