From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751240AbcBMDb4 (ORCPT ); Fri, 12 Feb 2016 22:31:56 -0500 Received: from mga09.intel.com ([134.134.136.24]:54000 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750925AbcBMDby (ORCPT ); Fri, 12 Feb 2016 22:31:54 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.22,438,1449561600"; d="scan'208";a="901946501" From: "Christopher S. Hall" To: tglx@linutronix.de, richardcochran@gmail.com, mingo@redhat.com, john.stultz@linaro.org, hpa@zytor.com, jeffrey.t.kirsher@intel.com Cc: "Christopher S. Hall" , x86@kernel.org, linux-kernel@vger.kernel.org, intel-wired-lan@lists.osuosl.org, netdev@vger.kernel.org, kevin.b.stanton@intel.com, kevin.j.clarke@intel.com Subject: [PATCH v7 1/8] time: Add cycles to nanoseconds translation Date: Fri, 12 Feb 2016 12:25:22 -0800 Message-Id: <1455308729-6280-2-git-send-email-christopher.s.hall@intel.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1455308729-6280-1-git-send-email-christopher.s.hall@intel.com> References: <1455308729-6280-1-git-send-email-christopher.s.hall@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The timekeeping code does not currently provide a way to translate externally provided clocksource cycles to system time. The cycle count is always provided by the result clocksource read() method internal to the timekeeping code. The added function timekeeping_cycles_to_ns() calculated a nanosecond value from a cycle count that can be added to tk_read_base.base value yielding the current system time. This allows clocksource cycle values external to the timekeeping code to provide a cycle count that can be transformed to system time. Signed-off-by: Christopher S. Hall Signed-off-by: John Stultz --- kernel/time/timekeeping.c | 25 +++++++++++++++++++++---- 1 file changed, 21 insertions(+), 4 deletions(-) diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 34b4ced..4243d28 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -298,17 +298,34 @@ u32 (*arch_gettimeoffset)(void) = default_arch_gettimeoffset; static inline u32 arch_gettimeoffset(void) { return 0; } #endif +static inline s64 timekeeping_delta_to_ns(struct tk_read_base *tkr, + cycle_t delta) +{ + s64 nsec; + + nsec = delta * tkr->mult + tkr->xtime_nsec; + nsec >>= tkr->shift; + + /* If arch requires, add in get_arch_timeoffset() */ + return nsec + arch_gettimeoffset(); +} + static inline s64 timekeeping_get_ns(struct tk_read_base *tkr) { cycle_t delta; - s64 nsec; delta = timekeeping_get_delta(tkr); + return timekeeping_delta_to_ns(tkr, delta); +} - nsec = (delta * tkr->mult + tkr->xtime_nsec) >> tkr->shift; +static inline s64 timekeeping_cycles_to_ns(struct tk_read_base *tkr, + cycle_t cycles) +{ + cycle_t delta; - /* If arch requires, add in get_arch_timeoffset() */ - return nsec + arch_gettimeoffset(); + /* calculate the delta since the last update_wall_time */ + delta = clocksource_delta(cycles, tkr->cycle_last, tkr->mask); + return timekeeping_delta_to_ns(tkr, delta); } /** -- 2.1.4