From patchwork Wed Jan 29 16:24:07 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Maxime Coquelin X-Patchwork-Id: 3552471 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 8C2E19F2E9 for ; Wed, 29 Jan 2014 16:26:05 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 48C15201BF for ; Wed, 29 Jan 2014 16:26:04 +0000 (UTC) Received: from casper.infradead.org (casper.infradead.org [85.118.1.10]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id A9DA6201BC for ; Wed, 29 Jan 2014 16:26:02 +0000 (UTC) Received: from merlin.infradead.org ([2001:4978:20e::2]) by casper.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1W8XxD-0001ox-QJ; Wed, 29 Jan 2014 16:25:32 +0000 Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1W8Xx7-0000bZ-FV; Wed, 29 Jan 2014 16:25:25 +0000 Received: from eu1sys200aog104.obsmtp.com ([207.126.144.117]) by merlin.infradead.org with smtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1W8Xwu-0000ZR-3w for linux-arm-kernel@lists.infradead.org; Wed, 29 Jan 2014 16:25:13 +0000 Received: from beta.dmz-eu.st.com ([164.129.1.35]) (using TLSv1) by eu1sys200aob104.postini.com ([207.126.147.11]) with SMTP ID DSNKUukrTUHEYGSGknIejea++9D0c+2CxIc9@postini.com; Wed, 29 Jan 2014 16:25:12 UTC Received: from zeta.dmz-eu.st.com (zeta.dmz-eu.st.com [164.129.230.9]) by beta.dmz-eu.st.com (STMicroelectronics) with ESMTP id 54C00118; Wed, 29 Jan 2014 16:23:34 +0000 (GMT) Received: from mail7.sgp.st.com (unknown [164.129.223.81]) by zeta.dmz-eu.st.com (STMicroelectronics) with ESMTP id 1A1D72C66D; Wed, 29 Jan 2014 16:24:22 +0000 (GMT) Received: from lmenx29l.st.com (lmenx29l.lme.st.com [10.201.23.80]) by mail7.sgp.st.com (MOS 4.3.3-GA) with ESMTP id BWY31350 (AUTH lme00137); Wed, 29 Jan 2014 17:24:22 +0100 From: Maxime COQUELIN To: Mike Turquette , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH 2/3] clk: divider: Add round to closest divider Date: Wed, 29 Jan 2014 17:24:07 +0100 Message-Id: <1391012648-12481-3-git-send-email-maxime.coquelin@st.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1391012648-12481-1-git-send-email-maxime.coquelin@st.com> References: <1391012648-12481-1-git-send-email-maxime.coquelin@st.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20140129_112512_385375_D4DF6B28 X-CRM114-Status: GOOD ( 21.68 ) X-Spam-Score: -4.2 (----) Cc: kernel@stlinux.com, maxime.coquelin@st.com X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-4.7 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP In some cases, we want to be able to round the divider to the closest one, instead than rounding up. This patch adds a new CLK_DIVIDER_ROUND_CLOSEST flag to specify the divider has to round to closest div, keeping rounding up as de default behaviour. Signed-off-by: Maxime Coquelin --- drivers/clk/clk-divider.c | 69 ++++++++++++++++++++++++++++++++++++++++-- include/linux/clk-provider.h | 3 ++ 2 files changed, 70 insertions(+), 2 deletions(-) diff --git a/drivers/clk/clk-divider.c b/drivers/clk/clk-divider.c index 2137d58..1eaa5d8 100644 --- a/drivers/clk/clk-divider.c +++ b/drivers/clk/clk-divider.c @@ -43,6 +43,17 @@ static unsigned int _get_table_maxdiv(const struct clk_div_table *table) return maxdiv; } +static unsigned int _get_table_mindiv(const struct clk_div_table *table) +{ + unsigned int mindiv = UINT_MAX; + const struct clk_div_table *clkt; + + for (clkt = table; clkt->div; clkt++) + if (clkt->div < mindiv) + mindiv = clkt->div; + return mindiv; +} + static unsigned int _get_maxdiv(struct clk_divider *divider) { if (divider->flags & CLK_DIVIDER_ONE_BASED) @@ -162,6 +173,24 @@ static int _round_up_table(const struct clk_div_table *table, int div) return up; } +static int _round_down_table(const struct clk_div_table *table, int div) +{ + const struct clk_div_table *clkt; + int down = _get_table_mindiv(table); + + for (clkt = table; clkt->div; clkt++) { + if (clkt->div == div) + return clkt->div; + else if (clkt->div > div) + continue; + + if ((div - clkt->div) < (div - down)) + down = clkt->div; + } + + return down; +} + static int _div_round_up(struct clk_divider *divider, unsigned long parent_rate, unsigned long rate) { @@ -175,6 +204,42 @@ static int _div_round_up(struct clk_divider *divider, return div; } +static int _div_round_closest(struct clk_divider *divider, + unsigned long parent_rate, unsigned long rate) +{ + int up, down, div; + + up = down = div = DIV_ROUND_CLOSEST(parent_rate, rate); + + if (divider->flags & CLK_DIVIDER_POWER_OF_TWO) { + up = __roundup_pow_of_two(div); + down = __rounddown_pow_of_two(div); + } else if (divider->table) { + up = _round_up_table(divider->table, div); + down = _round_down_table(divider->table, div); + } + + return (up - div) <= (div - down) ? up : down; +} + +static int _div_round(struct clk_divider *divider, unsigned long parent_rate, + unsigned long rate) +{ + if (divider->flags & CLK_DIVIDER_ROUND_CLOSEST) + return _div_round_closest(divider, parent_rate, rate); + + return _div_round_up(divider, parent_rate, rate); +} + +static bool _is_best_div(struct clk_divider *divider, + int rate, int now, int best) +{ + if (divider->flags & CLK_DIVIDER_ROUND_CLOSEST) + return abs(rate - now) < abs(rate - best); + + return now <= rate && now > best; +} + static int clk_divider_bestdiv(struct clk_hw *hw, unsigned long rate, unsigned long *best_parent_rate) { @@ -190,7 +255,7 @@ static int clk_divider_bestdiv(struct clk_hw *hw, unsigned long rate, if (!(__clk_get_flags(hw->clk) & CLK_SET_RATE_PARENT)) { parent_rate = *best_parent_rate; - bestdiv = _div_round_up(divider, parent_rate, rate); + bestdiv = _div_round(divider, parent_rate, rate); bestdiv = bestdiv == 0 ? 1 : bestdiv; bestdiv = bestdiv > maxdiv ? maxdiv : bestdiv; return bestdiv; @@ -217,7 +282,7 @@ static int clk_divider_bestdiv(struct clk_hw *hw, unsigned long rate, parent_rate = __clk_round_rate(__clk_get_parent(hw->clk), MULT_ROUND_UP(rate, i)); now = parent_rate / i; - if (now <= rate && now > best) { + if (_is_best_div(divider, rate, now, best)) { bestdiv = i; best = now; *best_parent_rate = parent_rate; diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h index 7e59253..595f0ba 100644 --- a/include/linux/clk-provider.h +++ b/include/linux/clk-provider.h @@ -275,6 +275,8 @@ struct clk_div_table { * of this register, and mask of divider bits are in higher 16-bit of this * register. While setting the divider bits, higher 16-bit should also be * updated to indicate changing divider bits. + * CLK_DIVIDER_ROUND_CLOSEST - Makes the best calculated divider to be rounded + * to the closest integer instead of the up one. */ struct clk_divider { struct clk_hw hw; @@ -290,6 +292,7 @@ struct clk_divider { #define CLK_DIVIDER_POWER_OF_TWO BIT(1) #define CLK_DIVIDER_ALLOW_ZERO BIT(2) #define CLK_DIVIDER_HIWORD_MASK BIT(3) +#define CLK_DIVIDER_ROUND_CLOSEST BIT(4) extern const struct clk_ops clk_divider_ops; struct clk *clk_register_divider(struct device *dev, const char *name,