From patchwork Tue Oct 17 09:17:38 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sean Young X-Patchwork-Id: 13424910 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2A0EDCDB484 for ; Tue, 17 Oct 2023 09:29:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234916AbjJQJ3x (ORCPT ); Tue, 17 Oct 2023 05:29:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36006 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343536AbjJQJSX (ORCPT ); Tue, 17 Oct 2023 05:18:23 -0400 Received: from gofer.mess.org (gofer.mess.org [88.97.38.141]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0DD75B0; Tue, 17 Oct 2023 02:18:22 -0700 (PDT) Received: by gofer.mess.org (Postfix, from userid 501) id A9B95100104; Tue, 17 Oct 2023 10:18:20 +0100 (BST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=mess.org; s=2020; t=1697534300; bh=ZxkAUO/92zmH6rwh0JhJYrp15Z9F2+z1H8tS7+HuIAw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=X3SAEy0Jh/uC6yOisGXO7E8FcJndlpHQXuu8+SOJ4mkBl3KlJFZR8bw5HHqXrUPhu 0kk+TnXZ6+gDrlv3ZVkUV5oNOTdQurFoCFubawAnFlbfYJ5ccFjZpgJr3JsMBFlGZa Cn4qV8Twe7S9JlOzwqKyZprOJEZvhMNh17Eg1jaI3soETrabW6bynYvIy6Xjihmlz4 asCxY7RJX728mIwLZo8gGkwPDoJZkXVRQiy9YeF8hv4INidGJ7aNXWEMXgk+ovT+Jk M+rXI1xcjarUx/PhahnUoDibOrVhId8muFWoQ2kPQ6TTfPJimwTarsgHmdpDXOqK/O 28+z35quysClA== 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 C326A1000FC; Tue, 17 Oct 2023 10:18:01 +0100 (BST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=mess.org; s=2020; t=1697534281; bh=ZxkAUO/92zmH6rwh0JhJYrp15Z9F2+z1H8tS7+HuIAw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=EHTwiL3HjDbFE9ouWJwhZWrVKb7IKfxwHplcViSwMPdSQNNi7zVHZSNGuwa4zxBLe NXLN3pVFxLQAHoGM/LAap5h9zZ1dfA4/Wpfq3gzT9tVDL4ApnVyuLSBjk9Z8mzC6aX yHabu3WGq1g1YPFis65Zm7lpbhhcfqkw3GBs0a8HfIRti7dCczkP75LRQq2u3Cs11G k5vLUMIblfnn5TTQRLkG7idVgOXz56iZMALKcDD2Ylcw1xglQCrhXlvbmP8zXzTBAb qs+4fyLB/sC5qHuUCgTx/20EyNzBsrbCRgZD0iL41/2Om+jOgdGiqH2D587OzRIJSq bUBmkCxDenmpQ== 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 , Ray Jui , Scott Branden , Broadcom internal kernel review list Cc: Sean Young , linux-rpi-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 2/3] pwm: bcm2835: allow pwm driver to be used in atomic context Date: Tue, 17 Oct 2023 10:17:38 +0100 Message-ID: X-Mailer: git-send-email 2.42.0 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org clk_get_rate() may do a mutex lock. Since the clock rate cannot change on an rpi, simply fetch it once. 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 bdfc2a5ec0d69..bd636ac1c5074 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); }