From patchwork Wed Dec 13 14:00:39 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Crt Mori X-Patchwork-Id: 10109983 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 D3F4A60352 for ; Wed, 13 Dec 2017 14:00:53 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id CA59728826 for ; Wed, 13 Dec 2017 14:00:53 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id BEE7C288DB; Wed, 13 Dec 2017 14:00:53 +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 AE49E28826 for ; Wed, 13 Dec 2017 14:00:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752909AbdLMOAv (ORCPT ); Wed, 13 Dec 2017 09:00:51 -0500 Received: from mail-wm0-f66.google.com ([74.125.82.66]:38924 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752957AbdLMOAs (ORCPT ); Wed, 13 Dec 2017 09:00:48 -0500 Received: by mail-wm0-f66.google.com with SMTP id i11so5278525wmf.4 for ; Wed, 13 Dec 2017 06:00:48 -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=R9jOhFqHOuGo2KAbEd8rqtgAWXd4zrxGgAjovJbguUK41QulhJB8yL16gqXko7NQh9 2WnLBFbW3ilFKhTsvUCwfG4yzkpr4dNxLH+v9AG3pmdZ4rm9uAxY2txmehVzNSgvGGk4 6nQdyUACJaK5n1TEPvgKiaR+LG5mvOE49Vqq79UtJdzDFd4UlliAbipBfbdG2dyYDtfY ISlwG60VbbZecL1IKuMLxaOuaoKpSNXaK2MkFfbmrZsO4h+2KBKtnF8AI/8St+xOh++W 0fVOwJ94ejfdLynwGXdb+8iLDqAOsz1WB8NOQWP7hMr3JctTiMROUL7zrYWhJrU75Xsf CvgQ== 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=AN4dzMi7kwi1m7sf5mnUXtZgLb1u/3lnz/uKpHY8HtOfu3GN3Sh81hb1iIkOdgBaHC YwzSeE4z1KaVG7uB6FlUz9sRl8z+w2CsSSlQsH+E8nTANJhEkdxeZGniDlifjFUd70yb 7D9cZ+1I9cL1hWNDlGL5jPVqNFmhpoL/2DnK9JUVr63cqeDz8wuErIghFcpaUDdSQcqm T/ZbTWLdl5QbfyZ1zm5DjaAezKBr+C/fCUC1eri24TL7Y6psKePF0OrAhKQQCsbzpIh9 pmTc7Pl88bdSlfhCfuAW9LpaHxYeXiggUdnVeGId/Pwxkua0RIPZkzZwm8s3XD3vowTw xd3A== X-Gm-Message-State: AKGB3mLepj4ZbI9wn7tnTU2EroaM+kzXH533KFvakKOnrPWdApnj8ilJ art42OUHCev2N8xpo7JJc1ovFhKsFKfH/Q== X-Google-Smtp-Source: ACJfBotGCVY9UKS6cjH6gKAxH/p5fu74xBt7Ek0iwIB7pAxPoVSXAt91Bn7yd4xws0l82MqJiExNaQ== X-Received: by 10.80.142.239 with SMTP id x44mr7763247edx.13.1513173647364; Wed, 13 Dec 2017 06:00:47 -0800 (PST) Received: from pc3729.tess.elex.be ([194.150.35.21]) by smtp.gmail.com with ESMTPSA id x28sm1551563edd.0.2017.12.13.06.00.45 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 13 Dec 2017 06:00:46 -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 v5 1/3] lib: Add strongly typed 64bit int_sqrt Date: Wed, 13 Dec 2017 15:00:39 +0100 Message-Id: <20171213140039.18482-1-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);