From patchwork Tue Aug 1 16:21:22 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: =?utf-8?q?Heiko_St=C3=BCbner?= X-Patchwork-Id: 9874963 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 0D4156037D for ; Tue, 1 Aug 2017 16:22:00 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id F346B286A8 for ; Tue, 1 Aug 2017 16:21:59 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id E81BD286B9; Tue, 1 Aug 2017 16:21:59 +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=-1.9 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,RCVD_IN_DNSWL_NONE autolearn=unavailable version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [65.50.211.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id A6E4F286A8 for ; Tue, 1 Aug 2017 16:21:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Date:Subject:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=5jwftuYqUsYdy15MN+g2+omhKGYkB9urwlTHf5fZ3G0=; b=LVGhhSwOrxMHA3 Xm2hu++IFoqus8m+9+08fy5b3MM9HTLf4/ICPRhQwiuniJ0C8X4IUgiysKxQpzoFpPhdnxivl93gG IiQF4Oad6huNxGMMxskykxHqxqKnerd8Nvl6tWy+DwdNU0teV0O02mW0VliRIMuORgW8OkZeB1qUC 5lXNA9udF7JmlV/I/+Hf3UJTMLpwi0mNg91Mq4mf1iV76yrdmFGhwD1q/gDq5f0ah1mMWpe8hJbHX 0YrUtR9vPvO0wXhzhW6w3V41RfbB6dIuoWxjQ27Hl0drixrLnYXFDGFzBgezql4fMNYyPYtDGQeIr o8MUB2YRqIP1dxlallbA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.87 #1 (Red Hat Linux)) id 1dcZvf-0000b0-T0; Tue, 01 Aug 2017 16:21:55 +0000 Received: from gloria.sntech.de ([95.129.55.99]) by bombadil.infradead.org with esmtps (Exim 4.87 #1 (Red Hat Linux)) id 1dcZva-0000TW-NC; Tue, 01 Aug 2017 16:21:53 +0000 Received: from [217.243.129.235] (helo=phil.localnet) by gloria.sntech.de with esmtpsa (TLS1.1:DHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.80) (envelope-from ) id 1dcZv9-0005xk-2S; Tue, 01 Aug 2017 18:21:23 +0200 From: Heiko Stuebner To: Elaine Zhang Subject: [PATCH 1/2] clk: fractional-divider: allow overriding of approximation Date: Tue, 01 Aug 2017 18:21:22 +0200 Message-ID: <5453089.AIzWDZk3ey@phil> User-Agent: KMail/5.2.3 (Linux/4.9.0-2-amd64; KDE/5.28.0; x86_64; ; ) In-Reply-To: <5990882.df1suBpf8V@phil> References: <1500624187-12165-1-git-send-email-zhangqing@rock-chips.com> <5990882.df1suBpf8V@phil> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20170801_092150_987966_EE127A1D X-CRM114-Status: UNSURE ( 9.25 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: huangtao@rock-chips.com, xxx@rock-chips.com, xf@rock-chips.com, mturquette@baylibre.com, sboyd@codeaurora.org, linux-kernel@vger.kernel.org, linux-rockchip@lists.infradead.org, cl@rock-chips.com, linux-clk@vger.kernel.org, linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP From: Elaine Zhang Fractional dividers may have special requirements concerning numerator and denominator selection that differ from just getting the best approximation. For example on Rockchip socs the denominator must be at least 20 times larger than the numerator to generate precise clock frequencies. Therefore add the ability to provide custom approximation functions. Signed-off-by: Elaine Zhang Tested-by: Elaine Zhang Acked-by: Stephen Boyd --- drivers/clk/clk-fractional-divider.c | 28 ++++++++++++++++++++-------- include/linux/clk-provider.h | 3 +++ 2 files changed, 23 insertions(+), 8 deletions(-) diff --git a/drivers/clk/clk-fractional-divider.c b/drivers/clk/clk-fractional-divider.c index aab904618eb6..fdf625fb10fa 100644 --- a/drivers/clk/clk-fractional-divider.c +++ b/drivers/clk/clk-fractional-divider.c @@ -49,16 +49,12 @@ static unsigned long clk_fd_recalc_rate(struct clk_hw *hw, return ret; } -static long clk_fd_round_rate(struct clk_hw *hw, unsigned long rate, - unsigned long *parent_rate) +static void clk_fd_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; - unsigned long m, n; - u64 ret; - - if (!rate || rate >= *parent_rate) - return *parent_rate; /* * Get rate closer to *parent_rate to guarantee there is no overflow @@ -71,7 +67,23 @@ static long clk_fd_round_rate(struct clk_hw *hw, unsigned long rate, rational_best_approximation(rate, *parent_rate, GENMASK(fd->mwidth - 1, 0), GENMASK(fd->nwidth - 1, 0), - &m, &n); + m, n); +} + +static long clk_fd_round_rate(struct clk_hw *hw, unsigned long rate, + unsigned long *parent_rate) +{ + struct clk_fractional_divider *fd = to_clk_fd(hw); + unsigned long m, n; + u64 ret; + + if (!rate || rate >= *parent_rate) + return *parent_rate; + + if (fd->approximation) + fd->approximation(hw, rate, parent_rate, &m, &n); + else + clk_fd_general_approximation(hw, rate, parent_rate, &m, &n); ret = (u64)*parent_rate * m; do_div(ret, n); diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h index c59c62571e4f..1fc113fbf955 100644 --- a/include/linux/clk-provider.h +++ b/include/linux/clk-provider.h @@ -565,6 +565,9 @@ struct clk_fractional_divider { u8 nwidth; u32 nmask; u8 flags; + void (*approximation)(struct clk_hw *hw, + unsigned long rate, unsigned long *parent_rate, + unsigned long *m, unsigned long *n); spinlock_t *lock; };