From patchwork Tue Aug 25 20:44:47 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Laurent Vivier X-Patchwork-Id: 510619 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 2548A14010F for ; Wed, 26 Aug 2015 06:47:46 +1000 (AEST) Received: from localhost ([::1]:34507 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZUL8C-0000Cq-A6 for incoming@patchwork.ozlabs.org; Tue, 25 Aug 2015 16:47:44 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:32992) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZUL5Y-0004KE-58 for qemu-devel@nongnu.org; Tue, 25 Aug 2015 16:45:01 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZUL5X-0000IF-6z for qemu-devel@nongnu.org; Tue, 25 Aug 2015 16:45:00 -0400 Received: from mx1.redhat.com ([209.132.183.28]:43268) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZUL5X-0000I6-1m for qemu-devel@nongnu.org; Tue, 25 Aug 2015 16:44:59 -0400 Received: from int-mx13.intmail.prod.int.phx2.redhat.com (int-mx13.intmail.prod.int.phx2.redhat.com [10.5.11.26]) by mx1.redhat.com (Postfix) with ESMTPS id B72AC5BA0F; Tue, 25 Aug 2015 20:44:58 +0000 (UTC) Received: from thinkpad.redhat.com (vpn1-5-196.ams2.redhat.com [10.36.5.196]) by int-mx13.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id t7PKipFo030113; Tue, 25 Aug 2015 16:44:57 -0400 From: Laurent Vivier To: qemu-devel@nongnu.org, Jia Liu Date: Tue, 25 Aug 2015 22:44:47 +0200 Message-Id: <1440535491-4511-4-git-send-email-lvivier@redhat.com> In-Reply-To: <1440535491-4511-1-git-send-email-lvivier@redhat.com> References: <1440535491-4511-1-git-send-email-lvivier@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.26 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH 3/7] openrisc: remove muldiv64() X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Originally, timers were ticks based, and it made sense to add ticks to current time to know when to trigger an alarm. But since commit: 7447545 change all other clock references to use nanosecond resolution accessors All timers use nanoseconds and we need to convert ticks to nanoseconds, by doing something like: y = muldiv64(x, get_ticks_per_sec(), TIMER_FREQ) where x is the number of device ticks and y the number of system ticks. y is used as nanoseconds in timer functions, it works because 1 tick is 1 nanosecond. (get_ticks_per_sec() is 10^9) But as openrisc timer frequency is 20 MHz, we can also do: y = x * 50; /* 20 MHz period is 50 ns */ Signed-off-by: Laurent Vivier --- hw/openrisc/cputimer.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/hw/openrisc/cputimer.c b/hw/openrisc/cputimer.c index 9c54945..560cb91 100644 --- a/hw/openrisc/cputimer.c +++ b/hw/openrisc/cputimer.c @@ -22,7 +22,7 @@ #include "hw/hw.h" #include "qemu/timer.h" -#define TIMER_FREQ (20 * 1000 * 1000) /* 20MHz */ +#define TIMER_PERIOD 50 /* 50 ns period for 20 MHz timer */ /* The time when TTCR changes */ static uint64_t last_clk; @@ -36,8 +36,7 @@ void cpu_openrisc_count_update(OpenRISCCPU *cpu) return; } now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); - cpu->env.ttcr += (uint32_t)muldiv64(now - last_clk, TIMER_FREQ, - get_ticks_per_sec()); + cpu->env.ttcr += (uint32_t)((now - last_clk) / TIMER_PERIOD); last_clk = now; } @@ -59,7 +58,7 @@ void cpu_openrisc_timer_update(OpenRISCCPU *cpu) } else { wait = (cpu->env.ttmr & TTMR_TP) - (cpu->env.ttcr & TTMR_TP); } - next = now + muldiv64(wait, get_ticks_per_sec(), TIMER_FREQ); + next = now + (uint64_t)wait * TIMER_PERIOD; timer_mod(cpu->env.timer, next); }