Messages in this thread | | | Subject | Re: [PATCH v3 2/2] watchdog: Add Spreadtrum watchdog driver | From | Guenter Roeck <> | Date | Mon, 30 Oct 2017 02:32:38 -0700 |
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On 10/30/2017 02:18 AM, Baolin Wang wrote: > Hi Guenter, > > (There are some problem with Eric's email, he can not receive this > email, so I help to reply his comments following yours. sorry for > troubles.) > >>>>> +#define SPRD_WDT_MAX_TIMEOUT 60 >>>> >>>> >>>> Is that really the maximum supported timeout ? Seems a bit low. >>>> Shouldn't it be something like (U32_MAX / SPRD_WDT_CNT_STEP) ? >>>> >>> >>> It supports the max value like as U32_MAX/SPRD_WDT_CNT_STEP, >>> but it doesn't unnecessary to support so big value, if the system can not >>> response it in 60s, the watchdog could trigger timeout. >>> >> It is customary to provide the highest possible value here. >> No one is forced to set such high values. You are making a choice for >> others here. But, sure, if you insist; not worth arguing about. > > Eric said 60s is better for us, thanks for your patient explanation. > >> >>>>> + >>>>> +#define SPRD_WDT_CNT_HIGH_VALUE 16 >>>> >>>> >>>> Maybe name it "SPRD_WDT_CNT_HIGH_SHIFT". It is not really a value, >>>> it is a shift. >>>> >>> >>> Yes, you are right, _SHIFT will be better. >>> >>>>> >>>>> +#define SPRD_WDT_LOW_VALUE_MASK GENMASK(15, 0) >>>>> +#define SPRD_WDT_CNT_VALUE_MAX GENMASK(31, 0) >>>> >>>> >>>> Does this mask serve a useful purpose ? >>>> >>> >>> OK, I will remove it, thanks! >>> >>>>> +#define SPRD_WDT_LOAD_TIMEOUT 1000 >>>>> + >>>>> +struct sprd_wdt { >>>>> + void __iomem *base; >>>>> + struct watchdog_device wdd; >>>>> + struct clk *enable; >>>>> + struct clk *rtc_enable; >>>>> + unsigned int irq; >>>>> +}; >>>>> + >>>>> +static inline struct sprd_wdt *to_sprd_wdt(struct watchdog_device *wdd) >>>>> +{ >>>>> + return container_of(wdd, struct sprd_wdt, wdd); >>>>> +} >>>>> + >>>>> +static inline void sprd_wdt_lock(void __iomem *addr) >>>>> +{ >>>>> + writel_relaxed(0x0, addr + SPRD_WDT_LOCK); >>>>> +} >>>>> + >>>>> +static inline void sprd_wdt_unlock(void __iomem *addr) >>>>> +{ >>>>> + writel_relaxed(SPRD_WDT_UNLOCK_KEY, addr + SPRD_WDT_LOCK); >>>>> +} >>>>> + >>>>> +static inline bool sprd_wdt_is_running(struct sprd_wdt *wdt) >>>>> +{ >>>>> + u32 val; >>>>> + >>>>> + val = readl_relaxed(wdt->base + SPRD_WDT_CTRL); >>>>> + return val & SPRD_WDT_NEW_VER_EN; >>>>> +} >>>>> + >>>>> +static irqreturn_t sprd_wdt_isr(int irq, void *dev_id) >>>>> +{ >>>>> + struct sprd_wdt *wdt = (struct sprd_wdt *)dev_id; >>>>> + >>>>> + sprd_wdt_unlock(wdt->base); >>>>> + writel_relaxed(SPRD_WDT_INT_CLEAR_BIT, wdt->base + >>>>> SPRD_WDT_INT_CLR); >>>>> + sprd_wdt_lock(wdt->base); >>>>> + watchdog_notify_pretimeout(&wdt->wdd); >>>>> + return IRQ_HANDLED; >>>>> +} >>>>> + >>>>> +static u32 sprd_wdt_get_cnt_value(struct sprd_wdt *wdt) >>>>> +{ >>>>> + u32 val; >>>>> + >>>>> + val = readl_relaxed(wdt->base + SPRD_WDT_CNT_HIGH) << >>>>> + SPRD_WDT_CNT_HIGH_VALUE; >>>>> + val |= readl_relaxed(wdt->base + SPRD_WDT_CNT_LOW) & >>>>> + SPRD_WDT_LOW_VALUE_MASK; >>>>> + >>>>> + return val; >>>>> +} >>>>> + >>>>> +static int sprd_wdt_load_value(struct sprd_wdt *wdt, u32 timeout, >>>>> + u32 pretimeout) >>>>> +{ >>>>> + u32 val, delay_cnt = 0; >>>>> + u32 tmr_step = timeout * SPRD_WDT_CNT_STEP; >>>>> + u32 prtmr_step = pretimeout * SPRD_WDT_CNT_STEP; >>>>> + >>>>> + sprd_wdt_unlock(wdt->base); >>>>> + writel_relaxed((tmr_step >> SPRD_WDT_CNT_HIGH_VALUE) & >>>>> + SPRD_WDT_LOW_VALUE_MASK, wdt->base + >>>>> SPRD_WDT_LOAD_HIGH); >>>>> + writel_relaxed((tmr_step & SPRD_WDT_LOW_VALUE_MASK), >>>>> + wdt->base + SPRD_WDT_LOAD_LOW); >>>>> + writel_relaxed((prtmr_step >> SPRD_WDT_CNT_HIGH_VALUE) & >>>>> + SPRD_WDT_LOW_VALUE_MASK, >>>>> + wdt->base + SPRD_WDT_IRQ_LOAD_HIGH); >>>>> + writel_relaxed(prtmr_step & SPRD_WDT_LOW_VALUE_MASK, >>>>> + wdt->base + SPRD_WDT_IRQ_LOAD_LOW); >>>>> + sprd_wdt_lock(wdt->base); >>>>> + >>>>> + /* >>>>> + * Waiting the load value operation done, >>>>> + * it needs two or three RTC clock cycles. >>>>> + */ >>>>> + do { >>>>> + val = readl_relaxed(wdt->base + SPRD_WDT_INT_RAW); >>>>> + if (!(val & SPRD_WDT_LD_BUSY_BIT)) >>>>> + break; >>>>> + >>>>> + cpu_relax(); >>>>> + } while (delay_cnt++ < SPRD_WDT_LOAD_TIMEOUT); >>>>> + >>>>> + if (delay_cnt >= SPRD_WDT_LOAD_TIMEOUT) >>>>> + return -EBUSY; >>>>> + return 0; >>>>> +} >>>>> + >>>>> +static int sprd_wdt_enable(struct sprd_wdt *wdt) >>>>> +{ >>>>> + u32 val; >>>>> + int ret; >>>>> + >>>>> + ret = clk_prepare_enable(wdt->enable); >>>>> + if (ret) >>>>> + return ret; >>>>> + ret = clk_prepare_enable(wdt->rtc_enable); >>>>> + if (ret) >>>>> + return ret; >>>>> + >>>>> + sprd_wdt_unlock(wdt->base); >>>>> + val = readl_relaxed(wdt->base + SPRD_WDT_CTRL); >>>>> + val |= SPRD_WDT_NEW_VER_EN; >>>>> + writel_relaxed(val, wdt->base + SPRD_WDT_CTRL); >>>>> + sprd_wdt_lock(wdt->base); >>>>> + return 0; >>>>> +} >>>>> + >>>>> +static void sprd_wdt_disable(struct sprd_wdt *wdt) >>>>> +{ >>>>> + sprd_wdt_unlock(wdt->base); >>>>> + writel_relaxed(0x0, wdt->base + SPRD_WDT_CTRL); >>>>> + sprd_wdt_lock(wdt->base); >>>>> + >>>>> + clk_disable_unprepare(wdt->rtc_enable); >>>>> + clk_disable_unprepare(wdt->enable); >>>>> +} >>>>> + >>>>> +static int sprd_wdt_start(struct watchdog_device *wdd) >>>>> +{ >>>>> + struct sprd_wdt *wdt = to_sprd_wdt(wdd); >>>>> + u32 val; >>>>> + int ret; >>>>> + >>>>> + ret = sprd_wdt_load_value(wdt, wdd->timeout, wdd->pretimeout); >>>>> + if (ret) >>>>> + return ret; >>>>> + >>>>> + sprd_wdt_unlock(wdt->base); >>>>> + val = readl_relaxed(wdt->base + SPRD_WDT_CTRL); >>>>> + val |= SPRD_WDT_CNT_EN_BIT | SPRD_WDT_INT_EN_BIT | >>>>> SPRD_WDT_RST_EN_BIT; >>>>> + writel_relaxed(val, wdt->base + SPRD_WDT_CTRL); >>>>> + sprd_wdt_lock(wdt->base); >>>>> + set_bit(WDOG_HW_RUNNING, &wdd->status); >>>>> + >>>>> + return 0; >>>>> +} >>>>> + >>>>> +static int sprd_wdt_stop(struct watchdog_device *wdd) >>>>> +{ >>>>> + struct sprd_wdt *wdt = to_sprd_wdt(wdd); >>>>> + u32 val; >>>>> + >>>>> + sprd_wdt_unlock(wdt->base); >>>>> + val = readl_relaxed(wdt->base + SPRD_WDT_CTRL); >>>>> + val &= ~(SPRD_WDT_CNT_EN_BIT | SPRD_WDT_RST_EN_BIT | >>>>> + SPRD_WDT_INT_EN_BIT); >>>>> + writel_relaxed(val, wdt->base + SPRD_WDT_CTRL); >>>>> + sprd_wdt_lock(wdt->base); >>>>> + return 0; >>>>> +} >>>>> + >>>>> +static int sprd_wdt_set_timeout(struct watchdog_device *wdd, >>>>> + u32 timeout) >>>>> +{ >>>>> + struct sprd_wdt *wdt = to_sprd_wdt(wdd); >>>>> + >>>>> + if (timeout == wdd->timeout) >>>>> + return 0; >>>>> + >>>>> + wdd->timeout = timeout; >>>>> + >>>>> + return sprd_wdt_load_value(wdt, timeout, wdd->pretimeout); >>>>> +} >>>>> + >>>>> +static int sprd_wdt_set_pretimeout(struct watchdog_device *wdd, >>>>> + u32 new_pretimeout) >>>>> +{ >>>>> + struct sprd_wdt *wdt = to_sprd_wdt(wdd); >>>>> + >>>>> + if (new_pretimeout == wdd->pretimeout) >>>>> + return 0; >>>> >>>> >>>> This is inconsistent. pretimeout == 0 is accepted until it is set >>>> to a non-zero value once, then 0 is no longer accepted. pretimeout==0 >>>> should reflect "pretimeout disabled". If that is not possible you >>>> need to set some non-0 default value in the probe function. >>>> >>> >>> I understand your opinion, I will fix it. >>> >>>>> + if (new_pretimeout <= wdd->min_timeout) >>>>> + return -EINVAL; >>>> >>>> >>>> Why is pretimeout == wdd->min_timeout invalid ? >>>> >>> >>> OK, you are right, it should be pretimeout < min_timeout. >>> >>>>> + >>>>> + wdd->pretimeout = new_pretimeout; >>>>> + >>>>> + return sprd_wdt_load_value(wdt, wdd->timeout, new_pretimeout); >>>>> +} >>>>> + >>>>> +static u32 sprd_wdt_get_timeleft(struct watchdog_device *wdd) >>>>> +{ >>>>> + struct sprd_wdt *wdt = to_sprd_wdt(wdd); >>>>> + u32 val; >>>>> + >>>>> + val = sprd_wdt_get_cnt_value(wdt); >>>>> + val = val / SPRD_WDT_CNT_STEP; >>>>> + >>>>> + return val; >>>>> +} >>>>> + >>>>> +static const struct watchdog_ops sprd_wdt_ops = { >>>>> + .owner = THIS_MODULE, >>>>> + .start = sprd_wdt_start, >>>>> + .stop = sprd_wdt_stop, >>>>> + .set_timeout = sprd_wdt_set_timeout, >>>>> + .set_pretimeout = sprd_wdt_set_pretimeout, >>>>> + .get_timeleft = sprd_wdt_get_timeleft, >>>> >>>> >>>> Just wondering - no heartbeat function ? Having to load the timer >>>> values for each heartbeat is expensive. >>>> >>> >>> Unfortunately, this watchdog has not RELOAD register. >>> >>>>> >>>>> +}; >>>>> + >>>>> +static const struct watchdog_info sprd_wdt_info = { >>>>> + .options = WDIOF_SETTIMEOUT | >>>>> + WDIOF_PRETIMEOUT | >>>>> + WDIOF_MAGICCLOSE | >>>>> + WDIOF_KEEPALIVEPING, >>>>> + .identity = "Spreadtrum Watchdog Timer", >>>>> +}; >>>>> + >>>>> +static int sprd_wdt_probe(struct platform_device *pdev) >>>>> +{ >>>>> + struct resource *wdt_res; >>>>> + struct sprd_wdt *wdt; >>>>> + int ret; >>>>> + >>>>> + wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL); >>>>> + if (!wdt) >>>>> + return -ENOMEM; >>>>> + >>>>> + wdt_res = platform_get_resource(pdev, IORESOURCE_MEM, 0); >>>>> + if (!wdt_res) { >>>>> + dev_err(&pdev->dev, "failed to memory resource\n"); >>>>> + return -ENOMEM; >>>>> + } >>>> >>>> >>>> Unnecessary error check and message. devm_ioremap_resource() >>>> returns an error if res is NULL. >>>> >>> >>> OK, I will fix it. >>> >>>>> >>>>> + >>>>> + wdt->base = devm_ioremap_resource(&pdev->dev, wdt_res); >>>>> + if (IS_ERR(wdt->base)) >>>> >>>> >>>> Move the error message to here. >>>> >>>>> + return PTR_ERR(wdt->base); >>>>> + >>>>> + wdt->enable = devm_clk_get(&pdev->dev, "enable"); >>>>> + if (IS_ERR(wdt->enable)) { >>>>> + dev_err(&pdev->dev, "can't get the enable clock\n"); >>>>> + return PTR_ERR(wdt->enable); >>>>> + } >>>>> + >>>>> + wdt->rtc_enable = devm_clk_get(&pdev->dev, "rtc_enable"); >>>>> + if (IS_ERR(wdt->rtc_enable)) { >>>>> + dev_err(&pdev->dev, "can't get the rtc enable clock\n"); >>>>> + return PTR_ERR(wdt->rtc_enable); >>>>> + } >>>>> + >>>>> + wdt->irq = platform_get_irq(pdev, 0); >>>>> + if (wdt->irq < 0) { >>>>> + dev_err(&pdev->dev, "failed to get IRQ resource\n"); >>>>> + return wdt->irq; >>>>> + } >>>>> + >>>>> + ret = devm_request_irq(&pdev->dev, wdt->irq, sprd_wdt_isr, >>>>> + IRQF_NO_SUSPEND, "sprd-wdt", (void >>>>> *)wdt); >>>>> + if (ret) { >>>>> + dev_err(&pdev->dev, "failed to register irq\n"); >>>>> + return ret; >>>>> + } >>>>> + >>>>> + wdt->wdd.info = &sprd_wdt_info; >>>>> + wdt->wdd.ops = &sprd_wdt_ops; >>>>> + wdt->wdd.parent = &pdev->dev; >>>>> + wdt->wdd.min_timeout = SPRD_WDT_MIN_TIMROUT; >>>>> + wdt->wdd.max_timeout = SPRD_WDT_MAX_TIMEOUT; >>>>> + >>>> >>>> You might want to set wdt->wdd.timeout to a default value. >>>> >>> >>> OK, I will set a default timeout value in case of no timeout-sec in >>> device-tree. >>> >>>>> >>>>> + ret = sprd_wdt_enable(wdt); >>>>> + if (ret) { >>>>> + dev_err(&pdev->dev, "failed to enable wdt\n"); >>>>> + return ret; >>>>> + } >>>>> + >>>> >>>> >>>> This needs a matching sprd_wdt_disable() call in the remove function. >>>> Best way to handle this would be to add devm_add_action() here. >>>> >>> >>> If add devm_add_action(), it will be called in the remove function, >>> but this is not our expect, if someone remove this module, we want it just >>> timeout. >>> >> >> But that leaves the watchdog enabled even if it was stopped (no call to >> sprd_wdt_disable()). > > Eric said It can not be stopped since we have set WATCHDOG_NOWAYOUT, > which means it will reboot the system when removing the watchdog. > >> Relying on NOWAYOUT would be a better option here. Again, you are >> making a choice for the user. > > we have set WATCHDOG_NOWAYOUT. > Yes, I understand, but that is configurable.
Guenter
>> >> >>>>> + watchdog_set_nowayout(&wdt->wdd, WATCHDOG_NOWAYOUT); >>>>> + watchdog_init_timeout(&wdt->wdd, 0, &pdev->dev); >>>>> + >>>>> + ret = watchdog_register_device(&wdt->wdd); >>>> >>>> >>>> Unfortunately this doesn't work. It leaves interrupts enabled >>>> after the watchdog device is removed in sprd_wdt_remove(), >>>> but the driver will be gone. I would suggest to use >>>> devm_watchdog_register_device() and reorder calls to request >>>> the interrupt after registering the watchdog device. Then you >>>> can drop the remove function entirely. >>>> >>> >>> Yes, you are right, I understand your opinion, and it is very important, >>> devm_watchdog_register_device() is better. Thanks. >>> >>>>> + if (ret) { >>>>> + sprd_wdt_disable(wdt); >>>>> + dev_err(&pdev->dev, "failed to register watchdog\n"); >>>>> + return ret; >>>>> + } >>>>> + platform_set_drvdata(pdev, wdt); >>>>> + >>>>> + return 0; >>>>> +} >>>>> + >>>>> +static int sprd_wdt_remove(struct platform_device *pdev) >>>>> +{ >>>>> + struct sprd_wdt *wdt = platform_get_drvdata(pdev); >>>>> + >>>>> + watchdog_unregister_device(&wdt->wdd); >>>>> + >>>>> + if (sprd_wdt_is_running(wdt)) >>>>> + dev_crit(&pdev->dev, "Device removed: Expect >>>>> reboot!\n"); >>>>> + return 0; >>>>> +} >>>>> + >>>>> +static int __maybe_unused sprd_wdt_pm_suspend(struct device *dev) >>>>> +{ >>>>> + struct watchdog_device *wdd = dev_get_drvdata(dev); >>>>> + struct sprd_wdt *wdt = dev_get_drvdata(dev); >>>>> + >>>>> + if (watchdog_active(wdd)) { >>>>> + sprd_wdt_stop(&wdt->wdd); >>>>> + sprd_wdt_disable(wdt); >>>> >>>> >>>> Are you sure you only want to disable the clocks if the watchdog was >>>> active ? >>>> That seems to be a bit inconsistent. >>>> >>> >>> This watchdog is in always on power domain, if system suspend, it needs to >>> disable it, or it will timeout. >>> >> That is not what I asked. I asked why it isn't >> >> if (watchdog_active(wdd)) >> sprd_wdt_stop(&wdt->wdd); >> >> sprd_wdt_disable(wdt); >> >> instead. > > Yes, Eric will fix this in next version. > >> >>>>> + } >>>>> + >>>>> + return 0; >>>>> +} >>>>> + >>>>> +static int __maybe_unused sprd_wdt_pm_resume(struct device *dev) >>>>> +{ >>>>> + struct watchdog_device *wdd = dev_get_drvdata(dev); >>>>> + struct sprd_wdt *wdt = dev_get_drvdata(dev); >>>>> + int ret; >>>>> + >>>>> + if (watchdog_active(wdd)) { >>>>> + ret = sprd_wdt_enable(wdt); >>>>> + if (ret) >>>>> + return ret; >>>>> + ret = sprd_wdt_start(&wdt->wdd); >>>>> + if (ret) { >>>>> + sprd_wdt_disable(wdt); >>>>> + return ret; >>>>> + } >>>> >>>> >>>> This can leave the system in an inconsistent state. Sometimes the wdt may >>>> be >>>> disabled, sometimes not. >>>> >>> >>> If watchdog enable failed, it means there is something wrong in this >>> system. >>> >> >> >> True. >> >> Guenter > > >
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