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Message-ID: <0de7e5c8-57a2-9b27-d8a8-ed7e0b394b02@roeck-us.net>
Date: Thu, 22 Apr 2021 20:28:58 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Wang Qing <wangqing@...o.com>,
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 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.
> + 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.
> + }
> /*
> * 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().
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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