From patchwork Mon Dec 4 15:32:12 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Crt Mori X-Patchwork-Id: 10090659 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 906A560329 for ; Mon, 4 Dec 2017 15:32:26 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 8077F29244 for ; Mon, 4 Dec 2017 15:32:26 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 744562924A; Mon, 4 Dec 2017 15:32:26 +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 0057B29244 for ; Mon, 4 Dec 2017 15:32:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751851AbdLDPcZ (ORCPT ); Mon, 4 Dec 2017 10:32:25 -0500 Received: from mail-wm0-f66.google.com ([74.125.82.66]:42683 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751821AbdLDPcY (ORCPT ); Mon, 4 Dec 2017 10:32:24 -0500 Received: by mail-wm0-f66.google.com with SMTP id l141so6548182wmg.1 for ; Mon, 04 Dec 2017 07:32:24 -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=KK/9Nl8icSQ6RgkUzAgDjGjqMfOt2ODA15tjciAq2CM=; b=YirL3ex225/U5ZQk6g8uzexhZM2Zi3x/HugCLtle7HjELjjyx4qx5mc+HAsVifqnsB y+k2gt/OU3h2VrT6Yty65uAQKFEKaHcffmGt0GeT8YHk+N6IhnZDythF49d8BcbXWk14 vC3+RFcuauxeT7ZkDGJqQV0dYL3G8Gblv6CkVr+cSW20rHWVsrNU/WGEP7F0BA1JHzey 79hmppo2lQvtGdm5HuTVaKx208xNECJjDX2oj1LXfEKx+m1uuvXCCyxdEHM8VN8gZB+7 sPETQvsJIaToVeZ4ou97TEAwzXHLhyjto3LvXyM2GokhGr0S64pKATMshC4CQdsk0jK3 F3Gg== 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=KK/9Nl8icSQ6RgkUzAgDjGjqMfOt2ODA15tjciAq2CM=; b=B7bA1Vg3qvIiUqvIw6An260zVjXwGE6HOTMuuBBdiuCJTBF2Ojy1QdVFTQvK71t4j6 vFDLCiHs+bOmAyBI+FSbd6zKrbE3eVf9BxQOk5O3/VwQjLYm8d2oHXBde6bstHUtGKGF hjJdvgTHssw8IIIftEhIwZ7HQdlKvcIymyDQoTFKWN8QNjkdfDoTvQvlBkr0gg5Qcj7l O+pKeBwY+9wfbNwTT7TCIbAIvihSQRMpbz2hZ3uY9JWJg6lpL6llX0m8ujdfJT58wEod a8Wl0F0R8tYGiw36BZHXAy0vF7uf30M03Llq0nOic/YjlArOilqVzSVkLwTxQOZBrbmP yEYw== X-Gm-Message-State: AJaThX466fRLq82QvaUD7T3VNrCtm6TE8MQRfLeJsBSbsOAEWDG319KU I+Vm9o+DW/dQoGk45c8midLOwA== X-Google-Smtp-Source: AGs4zManc8dTLzbvovY1bBq6XH9/PamBnVzzhPc7aFMKv/gD17HL3nKP7Rstc3hbqfeiOKjGKYf61w== X-Received: by 10.80.148.10 with SMTP id p10mr31701135eda.250.1512401543317; Mon, 04 Dec 2017 07:32:23 -0800 (PST) Received: from pc3729.tess.elex.be ([194.150.35.21]) by smtp.gmail.com with ESMTPSA id f11sm8928664edf.28.2017.12.04.07.32.21 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 04 Dec 2017 07:32:22 -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 v2 3/3] lib: Add strongly typed 64bit int_sqrt Date: Mon, 4 Dec 2017 16:32:12 +0100 Message-Id: <20171204153212.26270-1-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 | 27 +++++++++++++++++++++++++++ 2 files changed, 28 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..3a106ffb1069 100644 --- a/lib/int_sqrt.c +++ b/lib/int_sqrt.c @@ -36,3 +36,30 @@ 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); +