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([82.78.167.70]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-a6f56da43fbsm659014066b.39.2024.06.19.05.09.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 19 Jun 2024 05:09:44 -0700 (PDT) From: Claudiu X-Google-Original-From: Claudiu To: ulf.hansson@linaro.org, wim@linux-watchdog.org, linux@roeck-us.net, rafael@kernel.org Cc: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-watchdog@vger.kernel.org, claudiu.beznea@tuxon.dev, geert+renesas@glider.be, linux-renesas-soc@vger.kernel.org, Claudiu Beznea Subject: [PATCH RFC 1/3] pmdomain: core: Add a helper to power on the restart devices Date: Wed, 19 Jun 2024 15:09:18 +0300 Message-Id: <20240619120920.2703605-2-claudiu.beznea.uj@bp.renesas.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20240619120920.2703605-1-claudiu.beznea.uj@bp.renesas.com> References: <20240619120920.2703605-1-claudiu.beznea.uj@bp.renesas.com> Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Claudiu Beznea Restart devices (e.g., watchdog) may be part of a software-controlled power domain. In the case of watchdog devices, if they implement the struct watchdog::restart() API, this is called though: kernel_restart() -> machine_restart() -> do_kernel_restart() -> atomic_notifier_call_chain() -> watchdog_restart_notifier() The watchdog_restart_notifier() is called with local interrupts disabled and SMP disabled (machine_restart() calls local_irq_disable() and smp_send_stop() before calling do_kernel_restart()). If the restart device (e.g., watchdog) is part of a software-controlled power domain and this domain is off at the moment of restart, we need to power it on before configuring the watchdog device. Add the dev_pm_genpd_resume_restart_dev() function to power on a restart device in these scenarios. Signed-off-by: Claudiu Beznea --- drivers/pmdomain/core.c | 18 ++++++++++++++++++ include/linux/pm_domain.h | 2 ++ 2 files changed, 20 insertions(+) diff --git a/drivers/pmdomain/core.c b/drivers/pmdomain/core.c index 83d978743659..d05bd72f6cfe 100644 --- a/drivers/pmdomain/core.c +++ b/drivers/pmdomain/core.c @@ -1540,6 +1540,24 @@ void dev_pm_genpd_resume(struct device *dev) } EXPORT_SYMBOL_GPL(dev_pm_genpd_resume); +/** + * dev_pm_genpd_resume_restart_dev - Try to synchronously resume the genpd for + * a reset device + * @dev: The reset device that is attached to the genpd, which needs to be + * resumed. + * + * This routine should tipicaly be called for a restart device (e.g. watchdog) + * that needs to be resumed during system restart phase. + */ +void dev_pm_genpd_resume_restart_dev(struct device *dev) +{ + if (system_state != SYSTEM_RESTART) + return; + + dev_pm_genpd_resume(dev); +} +EXPORT_SYMBOL_GPL(dev_pm_genpd_resume_restart_dev); + #else /* !CONFIG_PM_SLEEP */ #define genpd_prepare NULL diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h index 71e4f0fb8867..9f8ecfa0bf3c 100644 --- a/include/linux/pm_domain.h +++ b/include/linux/pm_domain.h @@ -347,9 +347,11 @@ static inline void dev_pm_genpd_synced_poweroff(struct device *dev) #ifdef CONFIG_PM_GENERIC_DOMAINS_SLEEP void dev_pm_genpd_suspend(struct device *dev); void dev_pm_genpd_resume(struct device *dev); +void dev_pm_genpd_resume_restart_dev(struct device *dev); #else static inline void dev_pm_genpd_suspend(struct device *dev) {} static inline void dev_pm_genpd_resume(struct device *dev) {} +static inline void dev_pm_genpd_resume_restart_dev(struct device *dev) {} #endif /* OF PM domain providers */ From patchwork Wed Jun 19 12:09:19 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: claudiu beznea X-Patchwork-Id: 805903 Received: from mail-ej1-f44.google.com (mail-ej1-f44.google.com [209.85.218.44]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 351F613F439 for ; Wed, 19 Jun 2024 12:09:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.218.44 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718798990; 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([82.78.167.70]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-a6f56da43fbsm659014066b.39.2024.06.19.05.09.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 19 Jun 2024 05:09:46 -0700 (PDT) From: Claudiu X-Google-Original-From: Claudiu To: ulf.hansson@linaro.org, wim@linux-watchdog.org, linux@roeck-us.net, rafael@kernel.org Cc: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-watchdog@vger.kernel.org, claudiu.beznea@tuxon.dev, geert+renesas@glider.be, linux-renesas-soc@vger.kernel.org, Claudiu Beznea Subject: [PATCH RFC 2/3] watchdog: rzg2l_wdt: Keep the clocks prepared Date: Wed, 19 Jun 2024 15:09:19 +0300 Message-Id: <20240619120920.2703605-3-claudiu.beznea.uj@bp.renesas.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20240619120920.2703605-1-claudiu.beznea.uj@bp.renesas.com> References: <20240619120920.2703605-1-claudiu.beznea.uj@bp.renesas.com> Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Claudiu Beznea The watchdog restart handler is called with interrupts disabled. In rzg2l_wdt_restart() we call clk_prepare_enable() to enable the watchdog clocks. The prepare part of clk_prepare_enable() may sleep. Sleep in atomic context should not happen. The clock drivers for all the micro-architectures where the RZ/G2L watchdog driver is used are not implementing struct clk_ops::prepare(). Even so, to be sure we are not hitted by this at some point, keep the watchdog clocks prepared and only enable them in restart handler. It is guaranteed that clk_enable() can be called in atomic context. Reported-by: Ulf Hansson Closes: https://lore.kernel.org/all/CAPDyKFq1+cL1M9qGY0P58ETHUZHGymxQL0w92emUJPMe7a_GxA@mail.gmail.com Signed-off-by: Claudiu Beznea --- drivers/watchdog/rzg2l_wdt.c | 31 ++++++++++++++++++++++++++----- 1 file changed, 26 insertions(+), 5 deletions(-) diff --git a/drivers/watchdog/rzg2l_wdt.c b/drivers/watchdog/rzg2l_wdt.c index 2a35f890a288..6e3d7512f38c 100644 --- a/drivers/watchdog/rzg2l_wdt.c +++ b/drivers/watchdog/rzg2l_wdt.c @@ -166,8 +166,8 @@ static int rzg2l_wdt_restart(struct watchdog_device *wdev, struct rzg2l_wdt_priv *priv = watchdog_get_drvdata(wdev); int ret; - clk_prepare_enable(priv->pclk); - clk_prepare_enable(priv->osc_clk); + clk_enable(priv->pclk); + clk_enable(priv->osc_clk); if (priv->devtype == WDT_RZG2L) { ret = reset_control_deassert(priv->rstc); @@ -226,11 +226,28 @@ static const struct watchdog_ops rzg2l_wdt_ops = { .restart = rzg2l_wdt_restart, }; +static int rzg2l_clks_prepare(struct rzg2l_wdt_priv *priv) +{ + int ret; + + ret = clk_prepare(priv->pclk); + if (ret) + return ret; + + ret = clk_prepare(priv->osc_clk); + if (ret) + clk_unprepare(priv->pclk); + + return ret; +} + static void rzg2l_wdt_pm_disable(void *data) { - struct watchdog_device *wdev = data; + struct rzg2l_wdt_priv *priv = data; - pm_runtime_disable(wdev->parent); + pm_runtime_disable(priv->wdev.parent); + clk_unprepare(priv->osc_clk); + clk_unprepare(priv->pclk); } static int rzg2l_wdt_probe(struct platform_device *pdev) @@ -275,6 +292,10 @@ static int rzg2l_wdt_probe(struct platform_device *pdev) priv->devtype = (uintptr_t)of_device_get_match_data(dev); + ret = rzg2l_clks_prepare(priv); + if (ret) + return ret; + pm_runtime_enable(&pdev->dev); priv->wdev.info = &rzg2l_wdt_ident; @@ -287,7 +308,7 @@ static int rzg2l_wdt_probe(struct platform_device *pdev) watchdog_set_drvdata(&priv->wdev, priv); dev_set_drvdata(dev, priv); - ret = devm_add_action_or_reset(&pdev->dev, rzg2l_wdt_pm_disable, &priv->wdev); + ret = devm_add_action_or_reset(&pdev->dev, rzg2l_wdt_pm_disable, &priv); 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([82.78.167.70]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-a6f56da43fbsm659014066b.39.2024.06.19.05.09.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 19 Jun 2024 05:09:47 -0700 (PDT) From: Claudiu X-Google-Original-From: Claudiu To: ulf.hansson@linaro.org, wim@linux-watchdog.org, linux@roeck-us.net, rafael@kernel.org Cc: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-watchdog@vger.kernel.org, claudiu.beznea@tuxon.dev, geert+renesas@glider.be, linux-renesas-soc@vger.kernel.org, Claudiu Beznea Subject: [PATCH RFC 3/3] watchdog: rzg2l_wdt: Power on the PM domain in rzg2l_wdt_restart() Date: Wed, 19 Jun 2024 15:09:20 +0300 Message-Id: <20240619120920.2703605-4-claudiu.beznea.uj@bp.renesas.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20240619120920.2703605-1-claudiu.beznea.uj@bp.renesas.com> References: <20240619120920.2703605-1-claudiu.beznea.uj@bp.renesas.com> Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Claudiu Beznea The rzg2l_wdt_restart() is called in atomic context. Calling pm_runtime_{get_sync, resume_and_get}() or any other runtime PM resume APIs is not an option as it may lead to issues as described in commit e4cf89596c1f ("watchdog: rzg2l_wdt: Fix 'BUG: Invalid wait context'") that removed the pm_runtime_get_sync() and enabled directly the clocks. Starting with RZ/G3S the watchdog could be part of its own software-controlled power domain. In case the watchdog is not used the power domain is off and accessing watchdog registers leads to aborts. To solve this, the patch powers on the power domain using dev_pm_genpd_resume_restart_dev() API after enabling its clock. This is not sleeping or taking any other locks as the watchdog power domain is not registered with GENPD_FLAG_IRQ_SAFE flags. Signed-off-by: Claudiu Beznea --- drivers/watchdog/rzg2l_wdt.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/drivers/watchdog/rzg2l_wdt.c b/drivers/watchdog/rzg2l_wdt.c index 6e3d7512f38c..bbdbbaa7b82b 100644 --- a/drivers/watchdog/rzg2l_wdt.c +++ b/drivers/watchdog/rzg2l_wdt.c @@ -12,6 +12,7 @@ #include #include #include +#include #include #include #include @@ -169,6 +170,17 @@ static int rzg2l_wdt_restart(struct watchdog_device *wdev, clk_enable(priv->pclk); clk_enable(priv->osc_clk); + /* + * The device may be part of a power domain that is currently + * powered off. We need to power it on before accessing registers. + * We don't undo the dev_pm_genpd_resume_restart_dev() as the device + * need to be on for the reboot to happen. Also, as we are in atomic + * context here, there is no need to increment PM runtime usage counter + * (to make sure pm_runtime_active() doesn't return wrong code). + */ + if (!pm_runtime_active(wdev->parent)) + dev_pm_genpd_resume_restart_dev(wdev->parent); + if (priv->devtype == WDT_RZG2L) { ret = reset_control_deassert(priv->rstc); if (ret)