Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754535AbcJNLlD (ORCPT ); Fri, 14 Oct 2016 07:41:03 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:39617 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754478AbcJNLlB (ORCPT ); Fri, 14 Oct 2016 07:41:01 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Prarit Bhargava , Richard Cochran , Thomas Gleixner , Ingo Molnar , Andy Lutomirski , kevin.b.stanton@intel.com, kevin.j.clarke@intel.com, hpa@zytor.com, jeffrey.t.kirsher@intel.com, netdev@vger.kernel.org, "Christopher S. Hall" , John Stultz Subject: [PATCH 4.4 01/21] time: Add cycles to nanoseconds translation Date: Fri, 14 Oct 2016 13:40:39 +0200 Message-Id: <20161014114024.727012250@linuxfoundation.org> X-Mailer: git-send-email 2.10.0 In-Reply-To: <20161014114024.667943585@linuxfoundation.org> References: <20161014114024.667943585@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2558 Lines: 78 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Christopher S. Hall commit 6bd58f09e1d8cc6c50a824c00bf0d617919986a1 upstream. 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. Cc: Prarit Bhargava Cc: Richard Cochran Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Andy Lutomirski Cc: kevin.b.stanton@intel.com Cc: kevin.j.clarke@intel.com Cc: hpa@zytor.com Cc: jeffrey.t.kirsher@intel.com Cc: netdev@vger.kernel.org Reviewed-by: Thomas Gleixner Signed-off-by: Christopher S. Hall Signed-off-by: John Stultz Signed-off-by: Greg Kroah-Hartman --- kernel/time/timekeeping.c | 25 +++++++++++++++++++++---- 1 file changed, 21 insertions(+), 4 deletions(-) --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -298,17 +298,34 @@ u32 (*arch_gettimeoffset)(void) = defaul 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); } /**