From patchwork Wed Dec 6 09:56:04 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Crt Mori X-Patchwork-Id: 10095143 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id D716E60210 for ; Wed, 6 Dec 2017 09:56:16 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C87CD29C08 for ; Wed, 6 Dec 2017 09:56:16 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id BD29F29C76; Wed, 6 Dec 2017 09:56:16 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=2.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_HI,T_DKIM_INVALID autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4085829C08 for ; Wed, 6 Dec 2017 09:56:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752373AbdLFJ4P (ORCPT ); Wed, 6 Dec 2017 04:56:15 -0500 Received: from mail-wm0-f65.google.com ([74.125.82.65]:36394 "EHLO mail-wm0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754395AbdLFJ4N (ORCPT ); Wed, 6 Dec 2017 04:56:13 -0500 Received: by mail-wm0-f65.google.com with SMTP id b76so6074354wmg.1 for ; Wed, 06 Dec 2017 01:56:13 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=melexis.com; s=google; h=from:to:cc:subject:date:message-id; bh=mfn24FLYLGIHFDrz7tU6i54NUxtf9Yn2g/qJa129U8I=; b=n9gAoE/d4+/XiepBad5008CMKa7CifAaeRMf5J1naQuWYodiqhETwgjPeT6ktmhzIF 8LoL9gtFZeaYJrGrA1SFE60cAF3WlpEgHh/AqtinwcQeNV1D3ENGgQyrNtrGovGsXDKF 5yyv0Bs1m3/ppcfAFrmyf9XVSj/ogsivaYwDI0H5yGfKOZnYGhelcP9jrHrQxXv+5Ktz yIjqgZlLfnoedY444rgkXG91fA01azQ0vF2bYjbTKcdVUtwiezpCdYLgC65J/EgFILdC 1yjEjJxJIKvFJgg98KNzrFRSzziZU9EcqWtHgVM8j3ijdoKFM3rd3b3KPey80R+HiECT o83A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=mfn24FLYLGIHFDrz7tU6i54NUxtf9Yn2g/qJa129U8I=; b=eoLpeLxNsBzwcyzpSZbhlB0ydfZGlxkuGJtlCIFaCN06P8emePck6an9qU4kizaKAS pOYwg9fwwv0nSv3JVfAC6XMSy8ZBWc/QQCf9SaRyxjTE4XNJrw72SVGtjR9KugLEPZ3H 5iXvlv3CATWsZFAxeblesI8Mn1YRy1yrs7iPv0SSDkE3uuTS6wLfOttw5KaphMmbnwcQ aflAuaduo7x9FpKJWVswjVbUNfABYTaU+EurjYISHS/SblpYDGGKoBxyVwTSvS0fAYFv QRU9nsUWLumcbH9QtCKkHfBYNx+/F06S49ghfrFGXg6xVF1TMv09znMwEI2i3m+GqXbm 6z3g== X-Gm-Message-State: AJaThX4u1hyhb1U0+3NXPNmFdUkv+aWFhobqiE1vjdehIw2GWT9HgyOK 7TygKnGBAj84nf8mzrpITSrakA== X-Google-Smtp-Source: AGs4zMbPSFWptZLqi0sSFK41nzKQRxpdELdcusYb8ZnMNOs+f2tHeeHPl/DweD6V+rmbqKCaeU/pzQ== X-Received: by 10.80.204.197 with SMTP id b5mr39946450edj.249.1512554172476; Wed, 06 Dec 2017 01:56:12 -0800 (PST) Received: from pc3729.tess.elex.be ([194.150.35.21]) by smtp.gmail.com with ESMTPSA id e25sm1048943edc.64.2017.12.06.01.56.10 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 06 Dec 2017 01:56:11 -0800 (PST) From: Crt Mori To: Jonathan Cameron Cc: Ingo Molnar , Andrew Morton , Kees Cook , Rusty Russell , Ian Abbott , Larry Finger , Niklas Soderlund , Thomas Gleixner , Krzysztof Kozlowski , Masahiro Yamada , linux-kernel@vger.kernel.org, linux-iio@vger.kernel.org, Crt Mori Subject: [PATCH v3 3/3] lib: Add strongly typed 64bit int_sqrt Date: Wed, 6 Dec 2017 10:56:04 +0100 Message-Id: <20171206095604.8285-1-cmo@melexis.com> X-Mailer: git-send-email 2.15.0 Sender: linux-iio-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP There is no option to perform 64bit integer sqrt on 32bit platform. Added stronger typed int_sqrt64 enables the 64bit calculations to be performed on 32bit platforms. Although int_sqrt() is a rough approximation, the same algorithm is used in int_sqrt64() as good enough on 32bit platform. Signed-off-by: Crt Mori --- include/linux/kernel.h | 1 + lib/int_sqrt.c | 26 ++++++++++++++++++++++++++ 2 files changed, 27 insertions(+) diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 0ad4c3044cf9..09f53063f2c9 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -459,6 +459,7 @@ extern int kernel_text_address(unsigned long addr); extern int func_ptr_is_kernel_text(void *ptr); unsigned long int_sqrt(unsigned long); +u64 int_sqrt64(u64 x); extern void bust_spinlocks(int yes); extern int oops_in_progress; /* If set, an oops, panic(), BUG() or die() is in progress */ diff --git a/lib/int_sqrt.c b/lib/int_sqrt.c index 1ef4cc344977..de5836448ea3 100644 --- a/lib/int_sqrt.c +++ b/lib/int_sqrt.c @@ -36,3 +36,29 @@ unsigned long int_sqrt(unsigned long x) return y; } EXPORT_SYMBOL(int_sqrt); + +/** + * int_sqrt64 - strongly typed int_sqrt function + * @x: 64bit integer of which to calculate the sqrt + */ +u64 int_sqrt64(u64 x) +{ + u64 b, m, y = 0; + + if (x <= 1) + return x; + + m = 1ULL << (64 - 2); + while (m != 0) { + b = y + m; + y >>= 1; + + if (x >= b) { + x -= b; + y += m; + } + m >>= 2; + } + return y; +} +EXPORT_SYMBOL(int_sqrt64);