From patchwork Mon Dec 18 15:05:44 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Crt Mori X-Patchwork-Id: 10119839 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 1AF2C6019C for ; Mon, 18 Dec 2017 15:05:56 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 0CC5A28D51 for ; Mon, 18 Dec 2017 15:05:56 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 0100F28E26; Mon, 18 Dec 2017 15:05:55 +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 7763728D51 for ; Mon, 18 Dec 2017 15:05:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758301AbdLRPFy (ORCPT ); Mon, 18 Dec 2017 10:05:54 -0500 Received: from mail-wr0-f195.google.com ([209.85.128.195]:46201 "EHLO mail-wr0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752928AbdLRPFx (ORCPT ); Mon, 18 Dec 2017 10:05:53 -0500 Received: by mail-wr0-f195.google.com with SMTP id g17so5141758wrd.13 for ; Mon, 18 Dec 2017 07:05:53 -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=d69VwdAuFmqmTJC0t9td9zGCQqLesrE9Noe2MP61DLNqtbGbZiIOnWPSInLNDTuTCj ObneUDKKBl6XBZsnF7OebBtCY6EaQPyFfacE219Ikp0vv5RHbjf9bJihg+LNapZPvN35 CK+aJ7VFqV5vJ6cR2AeoQDr8fO235rHhxdI6mTxzpgGhsMatDU5dOXMdu/KlwsUoh+xE 3fviSNBc5w/IPktd9o/5vzFF8Y69CpKKeLpXSqu5bZkwHQywFOKop2r4/dNkfRydZ3z3 F5iuiMlXZ4uZGPBSAlooCVmliFF+tc/RlSVq142qZVoxsANeLWBHf8GXFZKxCyHWlPD2 yqJA== 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=HnCBYf3KFmm/oA92tMQYyhSp05C4fvK0/71saOPisGz+V6jIHhyKMiIY6m+2sOnVIo Ko8v5QD31hHVb0HiRClQ1KtyQl0XjiEvzArW+pY5LGfL7mawOnZ6inaebzXY3iGJclja d8qYlPAmA5aEJM1uQe6KLk8M12yXWOjpdnTD10cR8QHy56UNRi+rQBgJ9tIWA48vI0F7 n3Ff2/lAaKyu5W4SQTkqt1VnqCck3D8hRULViw0jKS2yEWHRmZt86JaNl8+d/QAdwdcR fJjkXzus9FSpLNsZp1UjgMT4wvX/xbrFK3yg97cykSh/06x+GjD0W+iU2u0NIDmH/VFf OD/g== X-Gm-Message-State: AKGB3mL/d/53s/39wQacRV9CvXlgTI15pd3gU2up/+1WUh1H/U+WLK0d 6vGwnwMPdXofyAnS5DhniP1Rnw== X-Google-Smtp-Source: ACJfBos5HvqRnRJPA9SFtEM64PZa12b4StKQUd25hntel/dKZLyV15zQkTApuCShOq3pbPw8AttSCg== X-Received: by 10.223.185.85 with SMTP id b21mr20914wrg.264.1513609552319; Mon, 18 Dec 2017 07:05:52 -0800 (PST) Received: from pc3729.tess.elex.be ([194.150.35.21]) by smtp.gmail.com with ESMTPSA id r64sm12242614wrb.62.2017.12.18.07.05.50 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 18 Dec 2017 07:05:50 -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 v6 1/3] lib: Add strongly typed 64bit int_sqrt Date: Mon, 18 Dec 2017 16:05:44 +0100 Message-Id: <20171218150544.8000-1-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);