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Message-ID: <3acb9bb1-763b-5af7-de3c-d7d8d3f5b2f7@roeck-us.net>
Date: Thu, 22 Apr 2021 21:26:35 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: 王擎 <wangqing@...o.com>
Cc: Wim Van Sebroeck <wim@...ux-watchdog.org>,
Rob Herring <robh+dt@...nel.org>,
Matthias Brugger <matthias.bgg@...il.com>,
linux-watchdog@...r.kernel.org, devicetree@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org,
linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V7 1/2] watchdog: mtk: support pre-timeout when the bark
irq is available
On 4/22/21 8:48 PM, 王擎 wrote:
>
>> On 4/22/21 7:53 PM, Wang Qing wrote:
>>> Use the bark interrupt as the pretimeout notifier if available.
>>>
>>> When the watchdog timer expires in dual mode, an interrupt will be
>>> triggered first, then the timing restarts. The reset signal will be
>>> initiated when the timer expires again.
>>>
>>> The pretimeout notification shall occur at timeout-sec/2.
>>>
>>> V2:
>>> - panic() by default if WATCHDOG_PRETIMEOUT_GOV is not enabled.
>>>
>>> V3:
>>> - Modify the pretimeout behavior, manually reset after the pretimeout
>>> - is processed and wait until timeout.
>>>
>>> V4:
>>> - Remove pretimeout related processing.
>>> - Add dual mode control separately.
>>>
>>> V5:
>>> - Fix some formatting and printing problems.
>>>
>>> V6:
>>> - Realize pretimeout processing through dualmode.
>>>
>>> V7:
>>> - Add set_pretimeout().
>>>
>>> Signed-off-by: Wang Qing <wangqing@...o.com>
>>> ---
>>> drivers/watchdog/mtk_wdt.c | 76 +++++++++++++++++++++++++++++++++++++++++++---
>>> 1 file changed, 71 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/drivers/watchdog/mtk_wdt.c b/drivers/watchdog/mtk_wdt.c
>>> index 97ca993..ab3ac5d
>>> --- a/drivers/watchdog/mtk_wdt.c
>>> +++ b/drivers/watchdog/mtk_wdt.c
>>> @@ -25,6 +25,7 @@
>>> #include <linux/reset-controller.h>
>>> #include <linux/types.h>
>>> #include <linux/watchdog.h>
>>> +#include <linux/interrupt.h>
>>>
>>> #define WDT_MAX_TIMEOUT 31
>>> #define WDT_MIN_TIMEOUT 1
>>> @@ -184,15 +185,23 @@ static int mtk_wdt_set_timeout(struct watchdog_device *wdt_dev,
>>> {
>>> struct mtk_wdt_dev *mtk_wdt = watchdog_get_drvdata(wdt_dev);
>>> void __iomem *wdt_base = mtk_wdt->wdt_base;
>>> + unsigned int timeout_interval = timeout;
>>> u32 reg;
>>>
>>> wdt_dev->timeout = timeout;
>>> -
>>> + /*
>>> + * In dual mode, irq will be triggered at timeout / 2
>>> + * the real timeout occurs at timeout
>>> + */
>>> + if (wdt_dev->pretimeout) {
>>> + wdt_dev->pretimeout = timeout / 2;
>>
>> min_timeout is set to 1. I don't this works well if timeout == 1.
>> You'll either need to set min_timeout to 2, or handle that case.
>
> It is appropriate to change min_timeout to 2.
>
>>
>>> + timeout_interval = wdt_dev->pretimeout;
>>
>> timeout_interval is unnecessary. Just update timeout accordingly.
>> It needs to take the situation of timeout == 1 into account, though.
>
> timeout represents the reset time. When the user calls timeout_show,
> He hopes to get the configured timeout, not the value changed
> by pre-timeout.
> I modify it like this more in line with the original intention.
>
>>
>>> + }
>>> /*
>>> * One bit is the value of 512 ticks
>>> * The clock has 32 KHz
>>> */
>>> - reg = WDT_LENGTH_TIMEOUT(timeout << 6) | WDT_LENGTH_KEY;
>>> + reg = WDT_LENGTH_TIMEOUT(timeout_interval << 6) | WDT_LENGTH_KEY;
>>> iowrite32(reg, wdt_base + WDT_LENGTH);
>>>
>>> mtk_wdt_ping(wdt_dev);
>>> @@ -239,13 +248,46 @@ static int mtk_wdt_start(struct watchdog_device *wdt_dev)
>>> return ret;
>>>
>>> reg = ioread32(wdt_base + WDT_MODE);
>>> - reg &= ~(WDT_MODE_IRQ_EN | WDT_MODE_DUAL_EN);
>>> + if (wdt_dev->pretimeout)
>>> + reg |= (WDT_MODE_IRQ_EN | WDT_MODE_DUAL_EN);
>>> + else
>>> + reg &= ~(WDT_MODE_IRQ_EN | WDT_MODE_DUAL_EN);
>>> reg |= (WDT_MODE_EN | WDT_MODE_KEY);
>>> iowrite32(reg, wdt_base + WDT_MODE);
>>>
>>> return 0;
>>> }
>>>
>>> +static int mtk_wdt_set_pretimeout(struct watchdog_device *wdd,
>>> + unsigned int timeout)
>>> +{
>>> + struct mtk_wdt_dev *mtk_wdt = watchdog_get_drvdata(wdd);
>>> + void __iomem *wdt_base = mtk_wdt->wdt_base;
>>> + u32 reg = ioread32(wdt_base + WDT_MODE);
>>> +
>>> + if (timeout && !wdd->pretimeout) {
>>> + wdd->pretimeout = wdd->timeout / 2;
>>> + reg |= (WDT_MODE_IRQ_EN | WDT_MODE_DUAL_EN);
>>> + } else if (!timeout && wdd->pretimeout) {
>>> + wdd->pretimeout = 0;
>>> + reg &= ~(WDT_MODE_IRQ_EN | WDT_MODE_DUAL_EN);
>>> + } else
>>> + return 0;
>>> +
>>> + iowrite32(reg, wdt_base + WDT_MODE);
>>
>> What is the point of setting the mode here ? It will
>> be set again in mtk_wdt_set_timeout(). Seems to me all
>> you need to do here is to set wdd->pretimeout,
>> then call mtk_wdt_set_timeout().
>
> mtk_wdt_set_timeout() only set timeout and ping().
> Here also need to config to the dualmode or not.
>
Ah, you are correct. Sorry, I confused this with the start function.
That makes me wonder if it would be better to extract a separate
function, mtk_wdt_set_mode(), for that purpose. Thoughts ?
Thanks,
Guenter
> Thanks,
> Qing
>>
>> Guenter
>>
>>> +
>>> + return mtk_wdt_set_timeout(wdd, wdd->timeout);
>>> +}
>>> +
>>> +static irqreturn_t mtk_wdt_isr(int irq, void *arg)
>>> +{
>>> + struct watchdog_device *wdd = arg;
>>> +
>>> + watchdog_notify_pretimeout(wdd);
>>> +
>>> + return IRQ_HANDLED;
>>> +}
>>> +
>>> static const struct watchdog_info mtk_wdt_info = {
>>> .identity = DRV_NAME,
>>> .options = WDIOF_SETTIMEOUT |
>>> @@ -253,12 +295,21 @@ static const struct watchdog_info mtk_wdt_info = {
>>> WDIOF_MAGICCLOSE,
>>> };
>>>
>>> +static const struct watchdog_info mtk_wdt_pt_info = {
>>> + .identity = DRV_NAME,
>>> + .options = WDIOF_SETTIMEOUT |
>>> + WDIOF_PRETIMEOUT |
>>> + WDIOF_KEEPALIVEPING |
>>> + WDIOF_MAGICCLOSE,
>>> +};
>>> +
>>> static const struct watchdog_ops mtk_wdt_ops = {
>>> .owner = THIS_MODULE,
>>> .start = mtk_wdt_start,
>>> .stop = mtk_wdt_stop,
>>> .ping = mtk_wdt_ping,
>>> .set_timeout = mtk_wdt_set_timeout,
>>> + .set_pretimeout = mtk_wdt_set_pretimeout,
>>> .restart = mtk_wdt_restart,
>>> };
>>>
>>> @@ -267,7 +318,7 @@ static int mtk_wdt_probe(struct platform_device *pdev)
>>> struct device *dev = &pdev->dev;
>>> struct mtk_wdt_dev *mtk_wdt;
>>> const struct mtk_wdt_data *wdt_data;
>>> - int err;
>>> + int err, irq;
>>>
>>> mtk_wdt = devm_kzalloc(dev, sizeof(*mtk_wdt), GFP_KERNEL);
>>> if (!mtk_wdt)
>>> @@ -279,7 +330,22 @@ static int mtk_wdt_probe(struct platform_device *pdev)
>>> if (IS_ERR(mtk_wdt->wdt_base))
>>> return PTR_ERR(mtk_wdt->wdt_base);
>>>
>>> - mtk_wdt->wdt_dev.info = &mtk_wdt_info;
>>> + irq = platform_get_irq(pdev, 0);
>>> + if (irq > 0) {
>>> + err = devm_request_irq(&pdev->dev, irq, mtk_wdt_isr, 0, "wdt_bark",
>>> + &mtk_wdt->wdt_dev);
>>> + if (err)
>>> + return err;
>>> +
>>> + mtk_wdt->wdt_dev.info = &mtk_wdt_pt_info;
>>> + mtk_wdt->wdt_dev.pretimeout = WDT_MAX_TIMEOUT / 2;
>>> + } else {
>>> + if (irq == -EPROBE_DEFER)
>>> + return -EPROBE_DEFER;
>>> +
>>> + mtk_wdt->wdt_dev.info = &mtk_wdt_info;
>>> + }
>>> +
>>> mtk_wdt->wdt_dev.ops = &mtk_wdt_ops;
>>> mtk_wdt->wdt_dev.timeout = WDT_MAX_TIMEOUT;
>>> mtk_wdt->wdt_dev.max_hw_heartbeat_ms = WDT_MAX_TIMEOUT * 1000;
>>>
>>
>
>
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