Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934700Ab3GRXVh (ORCPT ); Thu, 18 Jul 2013 19:21:37 -0400 Received: from smtp.codeaurora.org ([198.145.11.231]:58685 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933466Ab3GRXVe (ORCPT ); Thu, 18 Jul 2013 19:21:34 -0400 From: Stephen Boyd To: John Stultz Cc: linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Thomas Gleixner , Russell King , Catalin Marinas , Will Deacon , Christopher Covington Subject: [PATCH v4 01/17] clocksource: Extract max nsec calculation into separate function Date: Thu, 18 Jul 2013 16:21:14 -0700 Message-Id: <1374189690-10810-2-git-send-email-sboyd@codeaurora.org> X-Mailer: git-send-email 1.8.3.3.754.g9c3c367 In-Reply-To: <1374189690-10810-1-git-send-email-sboyd@codeaurora.org> References: <1374189690-10810-1-git-send-email-sboyd@codeaurora.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4389 Lines: 108 We need to calculate the same number in the clocksource code and the sched_clock code, so extract this code into its own function. We also drop the min_t and just use min() because the two types are the same. Signed-off-by: Stephen Boyd --- include/linux/clocksource.h | 2 ++ kernel/time/clocksource.c | 45 ++++++++++++++++++++++++++++++--------------- 2 files changed, 32 insertions(+), 15 deletions(-) diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h index dbbf8aa..67301a4 100644 --- a/include/linux/clocksource.h +++ b/include/linux/clocksource.h @@ -292,6 +292,8 @@ extern void clocksource_resume(void); extern struct clocksource * __init __weak clocksource_default_clock(void); extern void clocksource_mark_unstable(struct clocksource *cs); +extern u64 +clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask); extern void clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 minsec); diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c index 50a8736..637a14a 100644 --- a/kernel/time/clocksource.c +++ b/kernel/time/clocksource.c @@ -537,40 +537,55 @@ static u32 clocksource_max_adjustment(struct clocksource *cs) } /** - * clocksource_max_deferment - Returns max time the clocksource can be deferred - * @cs: Pointer to clocksource - * + * clocks_calc_max_nsecs - Returns maximum nanoseconds that can be converted + * @mult: cycle to nanosecond multiplier + * @shift: cycle to nanosecond divisor (power of two) + * @maxadj: maximum adjustment value to mult (~11%) + * @mask: bitmask for two's complement subtraction of non 64 bit counters */ -static u64 clocksource_max_deferment(struct clocksource *cs) +u64 clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask) { u64 max_nsecs, max_cycles; /* * Calculate the maximum number of cycles that we can pass to the * cyc2ns function without overflowing a 64-bit signed result. The - * maximum number of cycles is equal to ULLONG_MAX/(cs->mult+cs->maxadj) + * maximum number of cycles is equal to ULLONG_MAX/(mult+maxadj) * which is equivalent to the below. - * max_cycles < (2^63)/(cs->mult + cs->maxadj) - * max_cycles < 2^(log2((2^63)/(cs->mult + cs->maxadj))) - * max_cycles < 2^(log2(2^63) - log2(cs->mult + cs->maxadj)) - * max_cycles < 2^(63 - log2(cs->mult + cs->maxadj)) - * max_cycles < 1 << (63 - log2(cs->mult + cs->maxadj)) + * max_cycles < (2^63)/(mult + maxadj) + * max_cycles < 2^(log2((2^63)/(mult + maxadj))) + * max_cycles < 2^(log2(2^63) - log2(mult + maxadj)) + * max_cycles < 2^(63 - log2(mult + maxadj)) + * max_cycles < 1 << (63 - log2(mult + maxadj)) * Please note that we add 1 to the result of the log2 to account for * any rounding errors, ensure the above inequality is satisfied and * no overflow will occur. */ - max_cycles = 1ULL << (63 - (ilog2(cs->mult + cs->maxadj) + 1)); + max_cycles = 1ULL << (63 - (ilog2(mult + maxadj) + 1)); /* * The actual maximum number of cycles we can defer the clocksource is - * determined by the minimum of max_cycles and cs->mask. + * determined by the minimum of max_cycles and mask. * Note: Here we subtract the maxadj to make sure we don't sleep for * too long if there's a large negative adjustment. */ - max_cycles = min_t(u64, max_cycles, (u64) cs->mask); - max_nsecs = clocksource_cyc2ns(max_cycles, cs->mult - cs->maxadj, - cs->shift); + max_cycles = min(max_cycles, mask); + max_nsecs = clocksource_cyc2ns(max_cycles, mult - maxadj, shift); + + return max_nsecs; +} + +/** + * clocksource_max_deferment - Returns max time the clocksource can be deferred + * @cs: Pointer to clocksource + * + */ +static u64 clocksource_max_deferment(struct clocksource *cs) +{ + u64 max_nsecs; + max_nsecs = clocks_calc_max_nsecs(cs->mult, cs->shift, cs->maxadj, + cs->mask); /* * To ensure that the clocksource does not wrap whilst we are idle, * limit the time the clocksource can be deferred by 12.5%. 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