From patchwork Fri Oct 27 09:20:46 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sean Young X-Patchwork-Id: 13438425 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 8E90CC25B67 for ; Fri, 27 Oct 2023 09:22:13 +0000 (UTC) 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=Mbmr3/q4AFdq+TmqLOOPh8m/TAA34RS9/sscQbreLOc=; b=2yP0gAO6nvV8zy EDT7afwCuORFwRHmfLalyBXzJyf2VX2gS6QLHiREDdFmGy8PmQ8ZQNlRKJRK5enI9GwN3x50ahG2T 8sCb+LggUy542KxJ+s/063jMxffX3cyxk40v8KM//AGBAOFuRKmEncwzhD7a8vNCGEh6dwQCZbyZH e68BaXvPH/82g2JewcUcdyl0zfv05FIVuf6gTSOnDnAbVHRczSdl/niaNhk9AG75vg165FVKe/7pT Enz/azffJ/5xqGbUlstldZgjIvy7D8+XHTVur6ooEEt+frvMra4xHaFsXAeOz3KRFMc1xFB2NpeDt uPo7JaohX8mEg6WJnQUA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qwJ2G-00G17W-1V; Fri, 27 Oct 2023 09:21:44 +0000 Received: from gofer.mess.org ([88.97.38.141]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1qwJ2B-00G155-3D; Fri, 27 Oct 2023 09:21:43 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=mess.org; s=2020; t=1698398496; bh=DxPI5121StgRUTEEL0CSVrpqb1VBB6L4IQP86fCtZS4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=lHZ/P6p9cPOb4VIPy5szQEgn/RyoC+fp41jvypWr7jBKqTEFToIY56NgW0y4G/kMQ EZI/VSSCqTjeN5wrzXHslUtXbXGZ5a0C9LDxfd21U4wxtv3TXlrOY6Wy/auiVgdmhh tZGSpNMfV6rNxfqvZ5WOMxpsiL6LeGyDqBMAJhAIM5BcIIUuS0LJJe1PbWHvBNXQ1h oXfSMwlXJSfFVV4wasF+lVErBCyQlDScXkEW2jat6qFpJKd4NFxkqGRcxA85dekW5d bfZ/YxmPjASl5wMjBd9HJRDqopDotTqiBaxkG/dqu/USCTG+R7OStrUqTkrQex0hL7 XLPsss9PhfFSQ== Received: by gofer.mess.org (Postfix, from userid 501) id E42FA100102; Fri, 27 Oct 2023 10:21:36 +0100 (BST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=mess.org; s=2020; t=1698398482; bh=DxPI5121StgRUTEEL0CSVrpqb1VBB6L4IQP86fCtZS4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=eqRX3nAb8Kbz5B2eWpPVpDHhIwvGLQI7kThd56gEs7mUJDkr8eooxv+2Dvv+HBZ7T zWqZZmmhjvL6NHfnHUuBsw1z2fhtoxXGJLV09n2DZ2+tA03VpDODlJf1fDROjYQ/X2 fw3ZWzkwdFAn0R/Wmm4edM2MpvDqs4ysywkf4sy8Pr0ARCVMS9iXMVQew74bDjsKxo cbrataWnJDm1fGyQyVgZ2z+2JM/Iau4Na01myEkyv4KGAiX68mOenk8D5jICT4/jjJ GcqNVhjWMqwNMZtKZOHTIuhQMFED7NTp8uFnGHofAHxynmji2u7irN5Tf6lharrxWX UJFafEaXsitiA== Received: from bigcore.mess.org (unknown [IPv6:2a02:8011:d000:212:ca7f:54ff:fe51:14d6]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by gofer.mess.org (Postfix) with ESMTPSA id 63784100100; Fri, 27 Oct 2023 10:21:22 +0100 (BST) From: Sean Young To: linux-media@vger.kernel.org, linux-pwm@vger.kernel.org, Ivaylo Dimitrov , Thierry Reding , =?utf-8?q?Uwe_Kleine-K=C3=B6nig?= , Florian Fainelli , Broadcom internal kernel review list , Ray Jui , Scott Branden Cc: Sean Young , linux-rpi-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH v4 3/4] pwm: bcm2835: allow pwm driver to be used in atomic context Date: Fri, 27 Oct 2023 10:20:46 +0100 Message-ID: <0b35ca65d6f4d53d3beb1411a64970ea5f969060.1698398004.git.sean@mess.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: References: MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20231027_022140_194571_96BA7F12 X-CRM114-Status: GOOD ( 16.44 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org clk_get_rate() may do a mutex lock. Fetch the clock rate once, and prevent rate changes using clk_rate_exclusive_get(). Signed-off-by: Sean Young --- drivers/pwm/pwm-bcm2835.c | 30 ++++++++++++++++++++---------- 1 file changed, 20 insertions(+), 10 deletions(-) diff --git a/drivers/pwm/pwm-bcm2835.c b/drivers/pwm/pwm-bcm2835.c index bdfc2a5ec0d6..bd636ac1c507 100644 --- a/drivers/pwm/pwm-bcm2835.c +++ b/drivers/pwm/pwm-bcm2835.c @@ -28,6 +28,7 @@ struct bcm2835_pwm { struct device *dev; void __iomem *base; struct clk *clk; + unsigned long rate; }; static inline struct bcm2835_pwm *to_bcm2835_pwm(struct pwm_chip *chip) @@ -63,17 +64,11 @@ static int bcm2835_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, { struct bcm2835_pwm *pc = to_bcm2835_pwm(chip); - unsigned long rate = clk_get_rate(pc->clk); unsigned long long period_cycles; u64 max_period; u32 val; - if (!rate) { - dev_err(pc->dev, "failed to get clock rate\n"); - return -EINVAL; - } - /* * period_cycles must be a 32 bit value, so period * rate / NSEC_PER_SEC * must be <= U32_MAX. As U32_MAX * NSEC_PER_SEC < U64_MAX the @@ -88,13 +83,13 @@ static int bcm2835_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, * <=> period < ((U32_MAX * NSEC_PER_SEC + NSEC_PER_SEC/2) / rate * <=> period <= ceil((U32_MAX * NSEC_PER_SEC + NSEC_PER_SEC/2) / rate) - 1 */ - max_period = DIV_ROUND_UP_ULL((u64)U32_MAX * NSEC_PER_SEC + NSEC_PER_SEC / 2, rate) - 1; + max_period = DIV_ROUND_UP_ULL((u64)U32_MAX * NSEC_PER_SEC + NSEC_PER_SEC / 2, pc->rate) - 1; if (state->period > max_period) return -EINVAL; /* set period */ - period_cycles = DIV_ROUND_CLOSEST_ULL(state->period * rate, NSEC_PER_SEC); + period_cycles = DIV_ROUND_CLOSEST_ULL(state->period * pc->rate, NSEC_PER_SEC); /* don't accept a period that is too small */ if (period_cycles < PERIOD_MIN) @@ -103,7 +98,7 @@ static int bcm2835_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, writel(period_cycles, pc->base + PERIOD(pwm->hwpwm)); /* set duty cycle */ - val = DIV_ROUND_CLOSEST_ULL(state->duty_cycle * rate, NSEC_PER_SEC); + val = DIV_ROUND_CLOSEST_ULL(state->duty_cycle * pc->rate, NSEC_PER_SEC); writel(val, pc->base + DUTY(pwm->hwpwm)); /* set polarity */ @@ -156,18 +151,32 @@ static int bcm2835_pwm_probe(struct platform_device *pdev) if (ret) return ret; + ret = clk_rate_exclusive_get(pc->clk); + if (ret) + goto add_fail; + + pc->rate = clk_get_rate(pc->clk); + if (!pc->rate) { + dev_err(pc->dev, "failed to get clock rate\n"); + ret = -EINVAL; + goto rate_fail; + } + pc->chip.dev = &pdev->dev; pc->chip.ops = &bcm2835_pwm_ops; + pc->chip.atomic = true; pc->chip.npwm = 2; platform_set_drvdata(pdev, pc); ret = pwmchip_add(&pc->chip); if (ret < 0) - goto add_fail; + goto rate_fail; return 0; +rate_fail: + clk_rate_exclusive_put(pc->clk); add_fail: clk_disable_unprepare(pc->clk); return ret; @@ -179,6 +188,7 @@ static void bcm2835_pwm_remove(struct platform_device *pdev) pwmchip_remove(&pc->chip); + clk_rate_exclusive_put(pc->clk); clk_disable_unprepare(pc->clk); }