From patchwork Thu Aug 12 17:00:22 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andy Shevchenko X-Patchwork-Id: 12433921 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=-17.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT 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 A9187C4338F for ; Thu, 12 Aug 2021 17:00:55 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 2CE9E60527 for ; Thu, 12 Aug 2021 17:00:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 2CE9E60527 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Message-Id:Date:Subject:Cc :To:From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=5/T0v9gsHthuIiYrKxMqQoCYxXn0c12KyFQoghG3Ep0=; b=y5m8+0NSJlk5it CxYjWxUityQhlB6UoPQqDp2bBWBxr4alA7OXZHYaB11pLZIQbz8fvhAqTOvTnPh6e0N4XpjJdp67Y JcZ0ycb7UBloDr6M9nLnMYCBpsqSBRt7qqXOzMxjety+kSpTdrqfEWMu6GcO966k7+h0x71OYGVyP aksRux7px1c1cmYnkuEDbKYdJdviDsbxsZMyugazEiqITPyQscNR5PkzHwbT3aTuGot1fegfmgRaL dYaHJccsOY4Zl6333w3z2AWNlkDPI9vsjw04SDqPCENoSIrCpwUZElV35suzCfMlyJyjuJpvR05kr Eh5+VcS9Orkt4WNbHRHQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mEE4Y-00AhCc-OJ; Thu, 12 Aug 2021 17:00:50 +0000 Received: from mga02.intel.com ([134.134.136.20]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mEE4L-00Ah9B-Kb; Thu, 12 Aug 2021 17:00:39 +0000 X-IronPort-AV: E=McAfee;i="6200,9189,10074"; a="202592822" X-IronPort-AV: E=Sophos;i="5.84,316,1620716400"; d="scan'208";a="202592822" Received: from orsmga004.jf.intel.com ([10.7.209.38]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Aug 2021 10:00:34 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.84,316,1620716400"; d="scan'208";a="571539798" Received: from black.fi.intel.com ([10.237.72.28]) by orsmga004.jf.intel.com with ESMTP; 12 Aug 2021 10:00:29 -0700 Received: by black.fi.intel.com (Postfix, from userid 1003) id 13C93B1; Thu, 12 Aug 2021 20:00:28 +0300 (EEST) From: Andy Shevchenko To: "Rafael J. Wysocki" , Andy Shevchenko , Heiko Stuebner , Elaine Zhang , Stephen Boyd , linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, linux-clk@vger.kernel.org, linux-imx@nxp.com, linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org Cc: "Rafael J. Wysocki" , Len Brown , Michael Turquette , Abel Vesa , Shawn Guo , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , Lee Jones Subject: [PATCH v4 1/4] clk: fractional-divider: Export approximation algorithm to the CCF users Date: Thu, 12 Aug 2021 20:00:22 +0300 Message-Id: <20210812170025.67074-1-andriy.shevchenko@linux.intel.com> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210812_100037_761326_EEB3441A X-CRM114-Status: GOOD ( 18.51 ) X-BeenThere: linux-rockchip@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Upstream kernel work for Rockchip platforms List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-rockchip" Errors-To: linux-rockchip-bounces+linux-rockchip=archiver.kernel.org@lists.infradead.org At least one user currently duplicates some functions that are provided by fractional divider module. Let's export approximation algorithm and replace the open-coded variant. As a bonus the exported function will get better documentation in place. Signed-off-by: Andy Shevchenko Tested-by: Heiko Stuebner Acked-by: Heiko Stuebner --- v4: rebased on top of latest CLK codebase drivers/clk/clk-fractional-divider.c | 11 +++++++---- drivers/clk/clk-fractional-divider.h | 9 +++++++++ drivers/clk/rockchip/clk.c | 17 +++-------------- 3 files changed, 19 insertions(+), 18 deletions(-) create mode 100644 drivers/clk/clk-fractional-divider.h diff --git a/drivers/clk/clk-fractional-divider.c b/drivers/clk/clk-fractional-divider.c index b1e556f20911..535d299af646 100644 --- a/drivers/clk/clk-fractional-divider.c +++ b/drivers/clk/clk-fractional-divider.c @@ -14,6 +14,8 @@ #include #include +#include "clk-fractional-divider.h" + static inline u32 clk_fd_readl(struct clk_fractional_divider *fd) { if (fd->flags & CLK_FRAC_DIVIDER_BIG_ENDIAN) @@ -68,9 +70,10 @@ static unsigned long clk_fd_recalc_rate(struct clk_hw *hw, return ret; } -static void clk_fd_general_approximation(struct clk_hw *hw, unsigned long rate, - unsigned long *parent_rate, - unsigned long *m, unsigned long *n) +void clk_fractional_divider_general_approximation(struct clk_hw *hw, + unsigned long rate, + unsigned long *parent_rate, + unsigned long *m, unsigned long *n) { struct clk_fractional_divider *fd = to_clk_fd(hw); unsigned long scale; @@ -102,7 +105,7 @@ static long clk_fd_round_rate(struct clk_hw *hw, unsigned long rate, if (fd->approximation) fd->approximation(hw, rate, parent_rate, &m, &n); else - clk_fd_general_approximation(hw, rate, parent_rate, &m, &n); + clk_fractional_divider_general_approximation(hw, rate, parent_rate, &m, &n); ret = (u64)*parent_rate * m; do_div(ret, n); diff --git a/drivers/clk/clk-fractional-divider.h b/drivers/clk/clk-fractional-divider.h new file mode 100644 index 000000000000..4fa359a12ef4 --- /dev/null +++ b/drivers/clk/clk-fractional-divider.h @@ -0,0 +1,9 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +struct clk_hw; + +void clk_fractional_divider_general_approximation(struct clk_hw *hw, + unsigned long rate, + unsigned long *parent_rate, + unsigned long *m, + unsigned long *n); diff --git a/drivers/clk/rockchip/clk.c b/drivers/clk/rockchip/clk.c index 049e5e0b64f6..b7be7e11b0df 100644 --- a/drivers/clk/rockchip/clk.c +++ b/drivers/clk/rockchip/clk.c @@ -22,6 +22,8 @@ #include #include #include + +#include "../clk-fractional-divider.h" #include "clk.h" /* @@ -178,10 +180,8 @@ static void rockchip_fractional_approximation(struct clk_hw *hw, unsigned long rate, unsigned long *parent_rate, unsigned long *m, unsigned long *n) { - struct clk_fractional_divider *fd = to_clk_fd(hw); unsigned long p_rate, p_parent_rate; struct clk_hw *p_parent; - unsigned long scale; p_rate = clk_hw_get_rate(clk_hw_get_parent(hw)); if ((rate * 20 > p_rate) && (p_rate % rate != 0)) { @@ -190,18 +190,7 @@ static void rockchip_fractional_approximation(struct clk_hw *hw, *parent_rate = p_parent_rate; } - /* - * Get rate closer to *parent_rate to guarantee there is no overflow - * for m and n. In the result it will be the nearest rate left shifted - * by (scale - fd->nwidth) bits. - */ - scale = fls_long(*parent_rate / rate - 1); - if (scale > fd->nwidth) - rate <<= scale - fd->nwidth; - - rational_best_approximation(rate, *parent_rate, - GENMASK(fd->mwidth - 1, 0), GENMASK(fd->nwidth - 1, 0), - m, n); + clk_fractional_divider_general_approximation(hw, rate, parent_rate, m, n); } static struct clk *rockchip_clk_register_frac_branch( From patchwork Thu Aug 12 17:00:23 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andy Shevchenko X-Patchwork-Id: 12433927 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=-17.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham 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 69B13C4338F for ; Thu, 12 Aug 2021 17:01:32 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id EF2CB60F57 for ; Thu, 12 Aug 2021 17:01:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org EF2CB60F57 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=jiPt9AdgdsWccMNsx3ekOF/SKttyxlNCYlo93LESjCE=; b=ohQfQd6o2d37Ab SLpKNhItmsDIqb9S6dGXLJ9V3vJYEmHQ++FrLjXK+IhkKjOzloZVUUDloNzzEDmqUccHo7jiqDi9t LpYt602hnJxVShOXRyNw+/Pjm0fsUAY1zWCB6ED1JG7Ogt0zbUJd4QhODmKCVEmya3U2CBXrKQq2v 5vLUcA4dxCiaJVh7f8eV+QknruAKBNrrJ0p+l/zINcq/7qjMnrSS4jpwzkM8ZYyaQzxTnms1db/cV k4So/2EA1K7z7i2e2X2z3YII1VojzLIwM+W2Rdzo4Ev63oeNjz6Cs9kXam/dU7mpRR4LyOr37uezT Ugfz0QPN8vLiTKk/fY/A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mEE5A-00AhPl-HQ; Thu, 12 Aug 2021 17:01:28 +0000 Received: from mga05.intel.com ([192.55.52.43]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mEE4c-00AhDB-R4; Thu, 12 Aug 2021 17:00:56 +0000 X-IronPort-AV: E=McAfee;i="6200,9189,10074"; a="300986797" X-IronPort-AV: E=Sophos;i="5.84,316,1620716400"; d="scan'208";a="300986797" Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Aug 2021 10:00:41 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.84,316,1620716400"; d="scan'208";a="503934251" Received: from black.fi.intel.com ([10.237.72.28]) by orsmga001.jf.intel.com with ESMTP; 12 Aug 2021 10:00:30 -0700 Received: by black.fi.intel.com (Postfix, from userid 1003) id 1D23E9F; Thu, 12 Aug 2021 20:00:29 +0300 (EEST) From: Andy Shevchenko To: "Rafael J. Wysocki" , Andy Shevchenko , Heiko Stuebner , Elaine Zhang , Stephen Boyd , linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, linux-clk@vger.kernel.org, linux-imx@nxp.com, linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org Cc: "Rafael J. Wysocki" , Len Brown , Michael Turquette , Abel Vesa , Shawn Guo , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , Lee Jones Subject: [PATCH v4 2/4] clk: fractional-divider: Hide clk_fractional_divider_ops from wide audience Date: Thu, 12 Aug 2021 20:00:23 +0300 Message-Id: <20210812170025.67074-2-andriy.shevchenko@linux.intel.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210812170025.67074-1-andriy.shevchenko@linux.intel.com> References: <20210812170025.67074-1-andriy.shevchenko@linux.intel.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210812_100054_935051_D10DE061 X-CRM114-Status: GOOD ( 14.30 ) X-BeenThere: linux-rockchip@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Upstream kernel work for Rockchip platforms List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-rockchip" Errors-To: linux-rockchip-bounces+linux-rockchip=archiver.kernel.org@lists.infradead.org The providers are all located in drivers/clk/ and hence no need to export the clock operations to wider audience. Hide them by moving to drivers/clk/clk-fractional-divider.h. Signed-off-by: Andy Shevchenko --- v4: rebased on top of latest CLK codebase, fixed compilation error drivers/clk/clk-fractional-divider.h | 2 ++ drivers/clk/imx/clk-composite-7ulp.c | 1 + include/linux/clk-provider.h | 1 - 3 files changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/clk/clk-fractional-divider.h b/drivers/clk/clk-fractional-divider.h index 4fa359a12ef4..aaaef90b2777 100644 --- a/drivers/clk/clk-fractional-divider.h +++ b/drivers/clk/clk-fractional-divider.h @@ -2,6 +2,8 @@ struct clk_hw; +extern const struct clk_ops clk_fractional_divider_ops; + void clk_fractional_divider_general_approximation(struct clk_hw *hw, unsigned long rate, unsigned long *parent_rate, diff --git a/drivers/clk/imx/clk-composite-7ulp.c b/drivers/clk/imx/clk-composite-7ulp.c index 7c4f31b31eb0..d85ba78abbb1 100644 --- a/drivers/clk/imx/clk-composite-7ulp.c +++ b/drivers/clk/imx/clk-composite-7ulp.c @@ -10,6 +10,7 @@ #include #include +#include "../clk-fractional-divider.h" #include "clk.h" #define PCG_PCS_SHIFT 24 diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h index 7be81d5fcf8c..d8609aef2394 100644 --- a/include/linux/clk-provider.h +++ b/include/linux/clk-provider.h @@ -1023,7 +1023,6 @@ struct clk_fractional_divider { #define CLK_FRAC_DIVIDER_ZERO_BASED BIT(0) #define CLK_FRAC_DIVIDER_BIG_ENDIAN BIT(1) -extern const struct clk_ops clk_fractional_divider_ops; struct clk *clk_register_fractional_divider(struct device *dev, const char *name, const char *parent_name, unsigned long flags, void __iomem *reg, u8 mshift, u8 mwidth, u8 nshift, u8 nwidth, From patchwork Thu Aug 12 17:00:24 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andy Shevchenko X-Patchwork-Id: 12433923 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=-17.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT 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 BE81DC4338F for ; Thu, 12 Aug 2021 17:01:05 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 71AC260527 for ; Thu, 12 Aug 2021 17:01:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 71AC260527 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=4JJTvj/gRPT5TV40glPUq29rKJ2/oGyiPtaazLTCmlU=; b=05G78NYjt0xh+r j3+ehzcC/0AAbp4Osf6HWmS4HMerw2gZJA5ig2cqWa7qSADnsAcKios+PUsa6cuOHnbirzaBi4++Z UKc0mVMYv9tpS3c/vM/+ovy+PA3151ffPRnpqq5pH6EtGQxGQ/yp6nwSvep60qomK+gNvf70xjUjC yF6bQOMBVWG4YehEZu80VFoBqTGhWS32oLZvoPW8q4Ga0KiIOfmVML1FeVJB4yR1F+IF8MINJnu6p /iQMDKKlVM3qMpCzK8T9qburWIgqHpj7nXGcLa17qWNbaymRUDOZ61QYNaIl1Qpx3C1ue/2zSsBQN OLO5baAtV7BDQTmcrb3w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mEE4k-00AhF3-7J; Thu, 12 Aug 2021 17:01:02 +0000 Received: from mga14.intel.com ([192.55.52.115]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mEE4M-00Ah9E-FF; Thu, 12 Aug 2021 17:00:40 +0000 X-IronPort-AV: E=McAfee;i="6200,9189,10074"; a="215130320" X-IronPort-AV: E=Sophos;i="5.84,316,1620716400"; d="scan'208";a="215130320" Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Aug 2021 10:00:35 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.84,316,1620716400"; d="scan'208";a="446614409" Received: from black.fi.intel.com ([10.237.72.28]) by fmsmga007.fm.intel.com with ESMTP; 12 Aug 2021 10:00:29 -0700 Received: by black.fi.intel.com (Postfix, from userid 1003) id 2786B1E0; Thu, 12 Aug 2021 20:00:29 +0300 (EEST) From: Andy Shevchenko To: "Rafael J. Wysocki" , Andy Shevchenko , Heiko Stuebner , Elaine Zhang , Stephen Boyd , linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, linux-clk@vger.kernel.org, linux-imx@nxp.com, linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org Cc: "Rafael J. Wysocki" , Len Brown , Michael Turquette , Abel Vesa , Shawn Guo , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , Lee Jones , Liu Ying Subject: [PATCH v4 3/4] clk: fractional-divider: Introduce POWER_OF_TWO_PS flag Date: Thu, 12 Aug 2021 20:00:24 +0300 Message-Id: <20210812170025.67074-3-andriy.shevchenko@linux.intel.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210812170025.67074-1-andriy.shevchenko@linux.intel.com> References: <20210812170025.67074-1-andriy.shevchenko@linux.intel.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210812_100038_562147_B606D5C8 X-CRM114-Status: GOOD ( 17.89 ) X-BeenThere: linux-rockchip@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Upstream kernel work for Rockchip platforms List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-rockchip" Errors-To: linux-rockchip-bounces+linux-rockchip=archiver.kernel.org@lists.infradead.org The newly introduced POWER_OF_TWO_PS flag, when set, makes the flow to skip the assumption that the caller will use an additional 2^scale prescaler to get the desired clock rate. Reported-by: Liu Ying Signed-off-by: Andy Shevchenko --- v4: rebased on top of latest CLK codebase drivers/acpi/acpi_lpss.c | 4 ++-- drivers/clk/clk-fractional-divider.c | 10 ++++++---- drivers/mfd/intel-lpss.c | 3 ++- include/linux/clk-provider.h | 11 +++++++++-- 4 files changed, 19 insertions(+), 9 deletions(-) diff --git a/drivers/acpi/acpi_lpss.c b/drivers/acpi/acpi_lpss.c index 7f163074e4e4..30b1f511c2af 100644 --- a/drivers/acpi/acpi_lpss.c +++ b/drivers/acpi/acpi_lpss.c @@ -436,8 +436,8 @@ static int register_device_clock(struct acpi_device *adev, if (!clk_name) return -ENOMEM; clk = clk_register_fractional_divider(NULL, clk_name, parent, - 0, prv_base, - 1, 15, 16, 15, 0, NULL); + CLK_FRAC_DIVIDER_POWER_OF_TWO_PS, + prv_base, 1, 15, 16, 15, 0, NULL); parent = clk_name; clk_name = kasprintf(GFP_KERNEL, "%s-update", devname); diff --git a/drivers/clk/clk-fractional-divider.c b/drivers/clk/clk-fractional-divider.c index 535d299af646..6a3ed82fdae9 100644 --- a/drivers/clk/clk-fractional-divider.c +++ b/drivers/clk/clk-fractional-divider.c @@ -76,16 +76,18 @@ void clk_fractional_divider_general_approximation(struct clk_hw *hw, unsigned long *m, unsigned long *n) { struct clk_fractional_divider *fd = to_clk_fd(hw); - unsigned long scale; /* * Get rate closer to *parent_rate to guarantee there is no overflow * for m and n. In the result it will be the nearest rate left shifted * by (scale - fd->nwidth) bits. */ - scale = fls_long(*parent_rate / rate - 1); - if (scale > fd->nwidth) - rate <<= scale - fd->nwidth; + if (fd->flags & CLK_FRAC_DIVIDER_POWER_OF_TWO_PS) { + unsigned long scale = fls_long(*parent_rate / rate - 1); + + if (scale > fd->nwidth) + rate <<= scale - fd->nwidth; + } rational_best_approximation(rate, *parent_rate, GENMASK(fd->mwidth - 1, 0), GENMASK(fd->nwidth - 1, 0), diff --git a/drivers/mfd/intel-lpss.c b/drivers/mfd/intel-lpss.c index a9bf10bee796..0e15afc39f54 100644 --- a/drivers/mfd/intel-lpss.c +++ b/drivers/mfd/intel-lpss.c @@ -301,7 +301,8 @@ static int intel_lpss_register_clock_divider(struct intel_lpss *lpss, snprintf(name, sizeof(name), "%s-div", devname); tmp = clk_register_fractional_divider(NULL, name, __clk_get_name(tmp), - 0, lpss->priv, 1, 15, 16, 15, 0, + CLK_FRAC_DIVIDER_POWER_OF_TWO_PS, + lpss->priv, 1, 15, 16, 15, 0, NULL); if (IS_ERR(tmp)) return PTR_ERR(tmp); diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h index d8609aef2394..f59c875271a0 100644 --- a/include/linux/clk-provider.h +++ b/include/linux/clk-provider.h @@ -1001,6 +1001,12 @@ struct clk_hw *devm_clk_hw_register_fixed_factor(struct device *dev, * CLK_FRAC_DIVIDER_BIG_ENDIAN - By default little endian register accesses are * used for the divider register. Setting this flag makes the register * accesses big endian. + * CLK_FRAC_DIVIDER_POWER_OF_TWO_PS - By default the resulting fraction might + * be saturated and the caller will get quite far from the good enough + * approximation. Instead the caller may require, by setting this flag, + * to shift left by a few bits in case, when the asked one is quite small + * to satisfy the desired range of denominator. It assumes that on the + * caller's side the power-of-two capable prescaler exists. */ struct clk_fractional_divider { struct clk_hw hw; @@ -1020,8 +1026,9 @@ struct clk_fractional_divider { #define to_clk_fd(_hw) container_of(_hw, struct clk_fractional_divider, hw) -#define CLK_FRAC_DIVIDER_ZERO_BASED BIT(0) -#define CLK_FRAC_DIVIDER_BIG_ENDIAN BIT(1) +#define CLK_FRAC_DIVIDER_ZERO_BASED BIT(0) +#define CLK_FRAC_DIVIDER_BIG_ENDIAN BIT(1) +#define CLK_FRAC_DIVIDER_POWER_OF_TWO_PS BIT(2) struct clk *clk_register_fractional_divider(struct device *dev, const char *name, const char *parent_name, unsigned long flags, From patchwork Thu Aug 12 17:00:25 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andy Shevchenko X-Patchwork-Id: 12433925 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=-17.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT 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 C5E9FC4338F for ; Thu, 12 Aug 2021 17:01:18 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 5B9226023E for ; Thu, 12 Aug 2021 17:01:18 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 5B9226023E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=iT0eYTyh6YrR9eJemOk/rFCYL8U6wjsgS+mO0W1ZiP4=; b=FCua0B8ItpajpO gHtbaCqe5a8vOtVqvl3pI3wnrDvI2nTHDZHdEt+37A4WMlnDVajnNhzRh+Uap3aU/+Vt/quUGqWq9 xIuc27eRHHoTj3gKvbI/EizqAKB9NW1B8+TXQcUijfEsbh2E4Ij0pvs+2L864RgflHtQVfQaZOMjU mBoiYNL8WeCUi27W1G7pHCnIJVCPnxq0w9d8q6m0iHXxKAYVZBLHY9IodnB/IUAoL6+UCLtWt/f7h +s9Oe7pGoU69gbN8xi8DRw2Dr6PG5tHBuqajdh0vcjJaUdgCQUHiVR1OMjgbgHPzbPMR68hcVzwsz OnsfDdcbN4J2FGTNaAoA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mEE4v-00AhHz-0p; Thu, 12 Aug 2021 17:01:13 +0000 Received: from mga06.intel.com ([134.134.136.31]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mEE4O-00AhAK-Oj; Thu, 12 Aug 2021 17:00:42 +0000 X-IronPort-AV: E=McAfee;i="6200,9189,10074"; a="276435240" X-IronPort-AV: E=Sophos;i="5.84,316,1620716400"; d="scan'208";a="276435240" Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Aug 2021 10:00:38 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.84,316,1620716400"; d="scan'208";a="517527485" Received: from black.fi.intel.com ([10.237.72.28]) by FMSMGA003.fm.intel.com with ESMTP; 12 Aug 2021 10:00:29 -0700 Received: by black.fi.intel.com (Postfix, from userid 1003) id 30EA5238; Thu, 12 Aug 2021 20:00:29 +0300 (EEST) From: Andy Shevchenko To: "Rafael J. Wysocki" , Andy Shevchenko , Heiko Stuebner , Elaine Zhang , Stephen Boyd , linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, linux-clk@vger.kernel.org, linux-imx@nxp.com, linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org Cc: "Rafael J. Wysocki" , Len Brown , Michael Turquette , Abel Vesa , Shawn Guo , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , Lee Jones , Liu Ying Subject: [PATCH v4 4/4] clk: fractional-divider: Document the arithmetics used behind the code Date: Thu, 12 Aug 2021 20:00:25 +0300 Message-Id: <20210812170025.67074-4-andriy.shevchenko@linux.intel.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210812170025.67074-1-andriy.shevchenko@linux.intel.com> References: <20210812170025.67074-1-andriy.shevchenko@linux.intel.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210812_100040_919315_717CE72E X-CRM114-Status: GOOD ( 17.06 ) X-BeenThere: linux-rockchip@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Upstream kernel work for Rockchip platforms List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-rockchip" Errors-To: linux-rockchip-bounces+linux-rockchip=archiver.kernel.org@lists.infradead.org It appears that some code lines raise the question why they are needed and how they are participated in the calculus of the resulting values. Document this in a form of the top comment in the module file. Reported-by: Liu Ying Signed-off-by: Andy Shevchenko --- v4: rebased on top of latest CLK codebase drivers/clk/clk-fractional-divider.c | 35 +++++++++++++++++++++++++++- 1 file changed, 34 insertions(+), 1 deletion(-) diff --git a/drivers/clk/clk-fractional-divider.c b/drivers/clk/clk-fractional-divider.c index 6a3ed82fdae9..b4f365d97bd0 100644 --- a/drivers/clk/clk-fractional-divider.c +++ b/drivers/clk/clk-fractional-divider.c @@ -3,8 +3,39 @@ * Copyright (C) 2014 Intel Corporation * * Adjustable fractional divider clock implementation. - * Output rate = (m / n) * parent_rate. * Uses rational best approximation algorithm. + * + * Output is calculated as + * + * rate = (m / n) * parent_rate (1) + * + * This is useful when on die we have a prescaler block which asks for + * m (numerator) and n (denominator) values to be provided to satisfy + * the (1) as much as possible. + * + * Since m and n have the limitation by a range, e.g. + * + * n >= 1, n < N_width, where N_width = 2^nwidth (2) + * + * for some cases the output may be saturated. Hence, from (1) and (2), + * assuming the worst case when m = 1, the inequality + * + * floor(log2(parent_rate / rate)) <= nwidth (3) + * + * may be derived. Thus, in cases when + * + * (parent_rate / rate) >> N_width (4) + * + * we might scale up the rate by 2^scale (see the description of + * CLK_FRAC_DIVIDER_POWER_OF_TWO_PS for additional information), where + * + * scale = floor(log2(parent_rate / rate)) - nwidth (5) + * + * and assume that the IP, that needs m and n, has also its own + * prescaler, which is capable to divide by 2^scale. In this way + * we get the denominator to satisfy the desired range (2) and + * at the same time much much better result of m and n than simple + * saturated values. */ #include @@ -81,6 +112,8 @@ void clk_fractional_divider_general_approximation(struct clk_hw *hw, * Get rate closer to *parent_rate to guarantee there is no overflow * for m and n. In the result it will be the nearest rate left shifted * by (scale - fd->nwidth) bits. + * + * For the detailed explanation see the top comment in this file. */ if (fd->flags & CLK_FRAC_DIVIDER_POWER_OF_TWO_PS) { unsigned long scale = fls_long(*parent_rate / rate - 1);