From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2BE01C433E0 for ; Wed, 17 Jun 2020 08:28:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 087A22085B for ; Wed, 17 Jun 2020 08:28:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="cTNkPciZ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726540AbgFQI2h (ORCPT ); Wed, 17 Jun 2020 04:28:37 -0400 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:45847 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726025AbgFQI2g (ORCPT ); Wed, 17 Jun 2020 04:28:36 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1592382515; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=u3GjgZLiUiOxM4KW4wCX/5fbom+hzlu3qzH3FU/CI2Q=; b=cTNkPciZgl17dMb9SqRz7giUq5tVeQh/Kc9Fze08QYzr0+/rZv/1wrWLa4fQb5+/HsakCD vUiSpEShEuBGcKSfsEXLTLFkxnPBYedeQtYSkBe8BQBHmwFmOdXFAP9yO/3UiT3Ccc/j3Y du62zusVXt2Vg2WP5HGCgejYH4yUgfo= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-475-EvvX-GE5NZO2aV2eIq5a0w-1; Wed, 17 Jun 2020 04:28:31 -0400 X-MC-Unique: EvvX-GE5NZO2aV2eIq5a0w-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id B44E18C31F2; Wed, 17 Jun 2020 08:28:30 +0000 (UTC) Received: from gondolin (ovpn-112-222.ams2.redhat.com [10.36.112.222]) by smtp.corp.redhat.com (Postfix) with ESMTP id B2791512FE; Wed, 17 Jun 2020 08:28:26 +0000 (UTC) Date: Wed, 17 Jun 2020 10:27:03 +0200 From: Cornelia Huck To: Pierre Morel Cc: kvm@vger.kernel.org, linux-s390@vger.kernel.org, frankja@linux.ibm.com, david@redhat.com, thuth@redhat.com Subject: Re: [kvm-unit-tests PATCH v9 06/12] s390x: clock and delays caluculations Message-ID: <20200617102704.7755e11a.cohuck@redhat.com> In-Reply-To: <1592213521-19390-7-git-send-email-pmorel@linux.ibm.com> References: <1592213521-19390-1-git-send-email-pmorel@linux.ibm.com> <1592213521-19390-7-git-send-email-pmorel@linux.ibm.com> Organization: Red Hat GmbH MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Mon, 15 Jun 2020 11:31:55 +0200 Pierre Morel wrote: > The hardware gives us a good definition of the microsecond, > let's keep this information and let the routine accessing > the hardware keep all the information and return microseconds. > > Calculate delays in microseconds and take care about wrapping > around zero. > > Define values with macros and use inlines to keep the > milliseconds interface. > > Signed-off-by: Pierre Morel > --- > lib/s390x/asm/time.h | 29 +++++++++++++++++++++++++++-- > 1 file changed, 27 insertions(+), 2 deletions(-) > > diff --git a/lib/s390x/asm/time.h b/lib/s390x/asm/time.h > index 1791380..7f1d891 100644 > --- a/lib/s390x/asm/time.h > +++ b/lib/s390x/asm/time.h > @@ -13,14 +13,39 @@ > #ifndef ASM_S390X_TIME_H > #define ASM_S390X_TIME_H > > -static inline uint64_t get_clock_ms(void) > +#define STCK_SHIFT_US (63 - 51) > +#define STCK_MAX ((1UL << 52) - 1) > + > +static inline uint64_t get_clock_us(void) > { > uint64_t clk; > > asm volatile(" stck %0 " : : "Q"(clk) : "memory"); > > /* Bit 51 is incrememented each microsecond */ That comment may now be a tad non-obvious, because the details are hidden behind the #define? Anyway, no strong opinion. > - return (clk >> (63 - 51)) / 1000; > + return clk >> STCK_SHIFT_US; > +} > + > +static inline void udelay(unsigned long us) > +{ > + unsigned long startclk = get_clock_us(); > + unsigned long c; > + > + do { > + c = get_clock_us(); > + if (c < startclk) > + c += STCK_MAX; > + } while (c < startclk + us); > +} > + > +static inline void mdelay(unsigned long ms) > +{ > + udelay(ms * 1000); > +} > + > +static inline uint64_t get_clock_ms(void) > +{ > + return get_clock_us() / 1000; > } > > #endif Acked-by: Cornelia Huck