From patchwork Wed Nov 29 09:13:36 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sean Young X-Patchwork-Id: 13472472 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=mess.org header.i=@mess.org header.b="IFiTmvyg"; dkim=pass (2048-bit key) header.d=mess.org header.i=@mess.org header.b="HZqr3Bk0" Received: from gofer.mess.org (gofer.mess.org [88.97.38.141]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 51F7B19BF; Wed, 29 Nov 2023 01:14:08 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=mess.org; s=2020; t=1701249247; bh=GDt/QGFqEdFRkVDZgETPHCj6Jv9POqOqoTfpWoZLvRY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=IFiTmvygiy0uzNbZVDFBQ+6YkB4Xw8LjiUtZdUXgHEvQAqNhQ6nXcUDTuacv9OEoM wSZAXPSkX4KeTFdv1eY5eLMfY5fCgz9kpbk4mrne8HWGqYdtEjBhQuXSR+kmEL8JbL OYTY2yT/ZcHpwSFpuylcaI3xSU9puvE16RMiEcPLOg2NZM/7C2XHypCniIcQKZulda a4Q1rlrXCekCFN1q5RVfPbVkEcCk5kqYr85CnPGQSxJIjEhWs7yzGx3/oRIOfqAoWi nIiwEeaBobENupOsD8kSyerYHWNj6XNxVrtNJAqqC3g/gzEr3YzAJ7yfH/JshpQHjV Lk4UY1PfxJBjQ== Received: by gofer.mess.org (Postfix, from userid 501) id 3EC8F10029D; Wed, 29 Nov 2023 09:14:07 +0000 (GMT) X-Spam-Level: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=mess.org; s=2020; t=1701249229; bh=GDt/QGFqEdFRkVDZgETPHCj6Jv9POqOqoTfpWoZLvRY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HZqr3Bk07ZBh1TRRzsBJ3LgIh08ANfvAMRdGG3FuykyEvfE4w7BXktSqJKsP7UMLD kjfzaH7uM0BlNWPQuBXRLKAKfc+Cbzgdj0ywskPQsajoOu6SD0eTaEQe7wnunRxXqw brvA3SUE0eXFRXNBUjt+plaCy+58GmBy0Q9IH8aVNiveAilEtBnAVSoiAkDCxR4s3Q BR75PFAIDjXVMvLnvop57oIlOl7A4780cJeg71BPXSq34BDM2hIzgW3DbhTHcl8Ifk hq2HkyeLxjrpUXeoBc7DtaS31j+iZmJZ8XVLxSz3OxnEOvNivOg2hmp+rebjAfduD9 9KfTRtDJw8cGg== Received: from localhost.localdomain (bigcore-99.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 49223100101; Wed, 29 Nov 2023 09:13:49 +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 v6 3/4] pwm: bcm2835: allow pwm driver to be used in atomic context Date: Wed, 29 Nov 2023 09:13:36 +0000 Message-ID: <179dc1ce85702a8b64b43c0e0df656b0c5e3ce30.1701248996.git.sean@mess.org> 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 --- 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 9777babd5b95..52748194a3da 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 */ @@ -151,14 +146,29 @@ 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; 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; } @@ -167,6 +177,7 @@ 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;