From patchwork Sat Dec 26 06:41:33 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Syed Nayyar Waris X-Patchwork-Id: 11990263 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=-9.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 F3B37C433E9 for ; Sat, 26 Dec 2020 06:42:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CCC01221E9 for ; Sat, 26 Dec 2020 06:42:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727442AbgLZGmc (ORCPT ); Sat, 26 Dec 2020 01:42:32 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58782 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725801AbgLZGmb (ORCPT ); Sat, 26 Dec 2020 01:42:31 -0500 Received: from mail-pf1-x436.google.com (mail-pf1-x436.google.com [IPv6:2607:f8b0:4864:20::436]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6D1ADC061757; Fri, 25 Dec 2020 22:41:51 -0800 (PST) Received: by mail-pf1-x436.google.com with SMTP id q22so3468208pfk.12; Fri, 25 Dec 2020 22:41:51 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:mime-version:content-disposition :user-agent; bh=+Zz2ASXn2o1AAzNUsSqx+OfWOMVjrvSh/KaatXZVe1E=; b=Zccd4ckmnwoGwoJssq58yRMJlLCGNmgWKNNLNjPKTx3E17zvDtnuw7ilNjlBxNdrb1 qerj6rEtAE36abDCvqNWbiBN4PGhCbF9gYAHvwLWAarZWV2yWtrkAbfwy6bvczTs+cU1 oxZLn9yYTPfTetbf6NTfTm25aLlq0nw4MYlAWhMQ9vBVaHn3XCM2jzREW+f+ue9C1kE1 Itsjgn3yOWpBFoQ3SMaTelD8wQUxjd8i5Qup82bvW20ZGgkiEbjvMjoSiZ1JzLccNYyY oRa9db2gXY4ED0ytu8bH+R97APnOhhrv05pSSk01QrZr6GJMB4PtmZRjCXTnl7Lw2c8U xMTg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:mime-version :content-disposition:user-agent; bh=+Zz2ASXn2o1AAzNUsSqx+OfWOMVjrvSh/KaatXZVe1E=; b=bkO3mPmV25MDLX2ch027WUxlULgn/FyWNYoQfzAAx7mItuWxW0AaUodZRWD9raf7h5 am1/T1j/zsDOGEYFF1yh0a5cdwkqSzXvOjOdMuQnEGYwHahvZ3c5UkMU4QPUtXx/FhpY nhocYOcg1VuqPqBud4DbtzrK5iSoA8V9CxjriWxhCEn4ZdpBefCVssIX3dS8ZZxpe8VT PHKOjx+i1VqqtwPsVV7Unn7EhH0VloDqFVDJHojle2vZxd6LJQ4FExwXS3Pchob5xD/b 4S1xlR8BZhJY2BJpW0dBX9s/KXdPYsXkKv1S/ibi70YICe4eZ3C1gVV+2oyG9fU2WoHJ 7yYQ== X-Gm-Message-State: AOAM530JZ2Rxi6PJvANwKIgNdmyL3bSWnDSSdzaxSD7zw/ykHqHEs7XH cXsWwBQwpJmqpDjIWd/i+Bk= X-Google-Smtp-Source: ABdhPJxplND6wyf4phagc3MU2/poQTo714TNFqVHAG10cwXZBfUhioXwtZNEbctnfmqiAKSxLgpNMg== X-Received: by 2002:a62:c312:0:b029:1a9:19c7:a8e with SMTP id v18-20020a62c3120000b02901a919c70a8emr33462581pfg.74.1608964909710; Fri, 25 Dec 2020 22:41:49 -0800 (PST) Received: from syed.domain.name ([103.201.127.53]) by smtp.gmail.com with ESMTPSA id x7sm12250703pga.0.2020.12.25.22.41.42 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 25 Dec 2020 22:41:49 -0800 (PST) Date: Sat, 26 Dec 2020 12:11:33 +0530 From: Syed Nayyar Waris To: linus.walleij@linaro.org Cc: andriy.shevchenko@linux.intel.com, vilhelm.gray@gmail.com, michal.simek@xilinx.com, arnd@arndb.de, rrichter@marvell.com, linus.walleij@linaro.org, bgolaszewski@baylibre.com, yamada.masahiro@socionext.com, akpm@linux-foundation.org, rui.zhang@intel.com, daniel.lezcano@linaro.org, amit.kucheria@verdurent.com, linux-arch@vger.kernel.org, linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-pm@vger.kernel.org Subject: [PATCH 0/5] Introduce the for_each_set_clump macro Message-ID: MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.5.24 (2015-08-30) Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org Hello Linus, Since this patchset primarily affects GPIO drivers, would you like to pick it up through your GPIO tree? (Note: Patchset resent with the new macro and relevant functions shifted to a new header clump_bits.h [Linus Torvalds]) Michal, What do you think of [PATCH 5/5]? Is the conditional check needed? And also does returning -EINVAL look good? This patchset introduces a new generic version of for_each_set_clump. The previous version of for_each_set_clump8 used a fixed size 8-bit clump, but the new generic version can work with clump of any size but less than or equal to BITS_PER_LONG. The patchset utilizes the new macro in several GPIO drivers. The earlier 8-bit for_each_set_clump8 facilitated a for-loop syntax that iterates over a memory region entire groups of set bits at a time. For example, suppose you would like to iterate over a 32-bit integer 8 bits at a time, skipping over 8-bit groups with no set bit, where XXXXXXXX represents the current 8-bit group: Example: 10111110 00000000 11111111 00110011 First loop: 10111110 00000000 11111111 XXXXXXXX Second loop: 10111110 00000000 XXXXXXXX 00110011 Third loop: XXXXXXXX 00000000 11111111 00110011 Each iteration of the loop returns the next 8-bit group that has at least one set bit. But with the new for_each_set_clump the clump size can be different from 8 bits. Moreover, the clump can be split at word boundary in situations where word size is not multiple of clump size. Following are examples showing the working of new macro for clump sizes of 24 bits and 6 bits. Example 1: clump size: 24 bits, Number of clumps (or ports): 10 bitmap stores the bit information from where successive clumps are retrieved. /* bitmap memory region */ 0x00aa0000ff000000; /* Most significant bits */ 0xaaaaaa0000ff0000; 0x000000aa000000aa; 0xbbbbabcdeffedcba; /* Least significant bits */ Different iterations of for_each_set_clump:- 'offset' is the bit position and 'clump' is the 24 bit clump from the above bitmap. Iteration first: offset: 0 clump: 0xfedcba Iteration second: offset: 24 clump: 0xabcdef Iteration third: offset: 48 clump: 0xaabbbb Iteration fourth: offset: 96 clump: 0xaa Iteration fifth: offset: 144 clump: 0xff Iteration sixth: offset: 168 clump: 0xaaaaaa Iteration seventh: offset: 216 clump: 0xff Loop breaks because in the end the remaining bits (0x00aa) size was less than clump size of 24 bits. In above example it can be seen that in iteration third, the 24 bit clump that was retrieved was split between bitmap[0] and bitmap[1]. This example also shows that 24 bit zeroes if present in between, were skipped (preserving the previous for_each_set_macro8 behaviour). Example 2: clump size = 6 bits, Number of clumps (or ports) = 3. /* bitmap memory region */ 0x00aa0000ff000000; /* Most significant bits */ 0xaaaaaa0000ff0000; 0x0f00000000000000; 0x0000000000000ac0; /* Least significant bits */ Different iterations of for_each_set_clump: 'offset' is the bit position and 'clump' is the 6 bit clump from the above bitmap. Iteration first: offset: 6 clump: 0x2b Loop breaks because 6 * 3 = 18 bits traversed in bitmap. Here 6 * 3 is clump size * no. of clumps. GCC gives warning in bitmap_set_value(): https://godbolt.org/z/rjx34r Add explicit check to see if the value being written into the bitmap does not fall outside the bitmap. The situation that it is falling outside would never be possible in the code because the boundaries are required to be correct before the function is called. The responsibility is on the caller for ensuring the boundaries are correct. The code change is simply to silence the GCC warning messages because GCC is not aware that the boundaries have already been checked. As such, we're better off using __builtin_unreachable() here because we can avoid the latency of the conditional check entirely. Syed Nayyar Waris (5): clump_bits: Introduce the for_each_set_clump macro lib/test_bitmap.c: Add for_each_set_clump test cases gpio: thunderx: Utilize for_each_set_clump macro gpio: xilinx: Utilize generic bitmap_get_value and _set_value gpio: xilinx: Add extra check if sum of widths exceed 64 drivers/gpio/clump_bits.h | 101 ++++++++++++++++++++++++ drivers/gpio/gpio-thunderx.c | 12 ++- drivers/gpio/gpio-xilinx.c | 72 ++++++++++-------- lib/test_bitmap.c | 144 +++++++++++++++++++++++++++++++++++ 4 files changed, 292 insertions(+), 37 deletions(-) create mode 100644 drivers/gpio/clump_bits.h base-commit: bbe2ba04c5a92a49db8a42c850a5a2f6481e47eb