From patchwork Tue Dec 12 08:34:04 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Sean Young X-Patchwork-Id: 13488714 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=mess.org header.i=@mess.org header.b="PdDHjwkZ"; dkim=pass (2048-bit key) header.d=mess.org header.i=@mess.org header.b="pxTwT/yu" Received: from gofer.mess.org (gofer.mess.org [IPv6:2a02:8011:d000:212::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 63549F4; Tue, 12 Dec 2023 00:34:41 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=mess.org; s=2020; t=1702370080; bh=gTEti/8B23Lhh743tVWTymBVRCEpQHU5KFyCDk5okO0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PdDHjwkZrYIpKreAFvesoE6terpFGKIBaIpiJymKWFojQgagbOR7wt/H9h3zHDB4x HDXSUnbRhdpTkk2ugLr09zocrWcHJWIgxWb+wZpEWgiVyW+qNY/ywFziMPHLsBRpTb HQ57NtBJmsOJYA/w3DqxF2DfeWn8gkyFbq+r1D/6RbV4fuGLWAu8Q1/o/4XS0fj/z3 kY8o6KqnV9rhRbD8ZGfyCOuZDGovctXBKZquOFFP81ybVD9qeU5VjTTYf1Zc/GgcQQ moNLrbxsreLm/rJIPjMdmPpiWWz803eI9q0LJ0hpok+EKeSw6+bBoPAC6tQ8q3qq1U fV92GYeNxpNbA== Received: by gofer.mess.org (Postfix, from userid 501) id 37EAB100A00; Tue, 12 Dec 2023 08:34:40 +0000 (GMT) X-Spam-Level: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=mess.org; s=2020; t=1702370062; bh=gTEti/8B23Lhh743tVWTymBVRCEpQHU5KFyCDk5okO0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=pxTwT/yu6GbqALKFR6VoMRiIFXgE8GntD/iXPUVaPjQfJF49/FqkAtQtcpqxIqV3o ZwIMYifyK/VqRJ8JJx7/w1+8wXYCfmh3uj/uOEGMURFEM5ZtwNsschKbRYti5WuRuS 8DoHG+Ltz0a245V2kiAOds0OHKmz8Nw/4PHv/JDWhuKIkG9TofUYGeq5MzQabz9xWf KBW32GBSlXHVVSrAy9lBSNOnXoovEB4VQ/M1gkK0bs4uSOALyuMuyFI65YqBkVGD0J nRbpeqEI05LIVcGyqtQhokCAyMxV3hX5Eb24TBppmawjv2X8ZTOWEKKFM/iykl0LuW y/a7gJlj2/Z/g== Received: from localhost.localdomain (bigcore-58.local [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 E672310029E; Tue, 12 Dec 2023 08:34:22 +0000 (GMT) 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 v8 5/6] pwm: bcm2835: Allow PWM driver to be used in atomic context Date: Tue, 12 Dec 2023 08:34:04 +0000 Message-ID: X-Mailer: git-send-email 2.43.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-media@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 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 Reviewed-by: Florian Fainelli Reviewed-by: Uwe Kleine-König --- drivers/pwm/pwm-bcm2835.c | 31 +++++++++++++++++++++---------- 1 file changed, 21 insertions(+), 10 deletions(-) diff --git a/drivers/pwm/pwm-bcm2835.c b/drivers/pwm/pwm-bcm2835.c index ab30667f4f951..309d52ec43bbe 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 */ @@ -151,16 +146,31 @@ static int bcm2835_pwm_probe(struct platform_device *pdev) return dev_err_probe(&pdev->dev, PTR_ERR(pc->clk), "clock not found\n"); + ret = clk_rate_exclusive_get(pc->clk); + if (ret) + return dev_err_probe(&pdev->dev, ret, + "fail to get exclusive rate\n"); + + pc->rate = clk_get_rate(pc->clk); + if (!pc->rate) { + clk_rate_exclusive_put(pc->clk); + return dev_err_probe(&pdev->dev, -EINVAL, + "failed to get clock rate\n"); + } + 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 = devm_pwmchip_add(&pdev->dev, &pc->chip); - if (ret < 0) + if (ret < 0) { + clk_rate_exclusive_put(pc->clk); return dev_err_probe(&pdev->dev, ret, "failed to add pwmchip\n"); + } return 0; } @@ -169,6 +179,7 @@ static int bcm2835_pwm_suspend(struct device *dev) { struct bcm2835_pwm *pc = dev_get_drvdata(dev); + clk_rate_exclusive_put(pc->clk); clk_disable_unprepare(pc->clk); return 0;