linux-kernel - [PATCH V3] watchdog: mtk: support pre-timeout when the bark irq is available

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Message-Id: <1618400929-17013-1-git-send-email-wangqing@vivo.com>
Date:   Wed, 14 Apr 2021 19:48:49 +0800
From:   Wang Qing <wangqing@...o.com>
To:     Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Matthias Brugger <matthias.bgg@...il.com>,
        linux-watchdog@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:     Wang Qing <wangqing@...o.com>
Subject: [PATCH V3] watchdog: mtk: support pre-timeout when the bark irq is available

Use the bark interrupt as the pretimeout notifier if available.

By default, the pretimeout notification shall occur one second earlier
than the timeout.

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.

Signed-off-by: Wang Qing <wangqing@...o.com>
---
 drivers/watchdog/mtk_wdt.c | 62 ++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 57 insertions(+), 5 deletions(-)

diff --git a/drivers/watchdog/mtk_wdt.c b/drivers/watchdog/mtk_wdt.c
index 97ca993..7bef1e3
--- 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
@@ -234,18 +235,46 @@ static int mtk_wdt_start(struct watchdog_device *wdt_dev)
 	void __iomem *wdt_base = mtk_wdt->wdt_base;
 	int ret;
 
-	ret = mtk_wdt_set_timeout(wdt_dev, wdt_dev->timeout);
+	ret = mtk_wdt_set_timeout(wdt_dev, wdt_dev->timeout - wdt_dev->pretimeout);
 	if (ret < 0)
 		return ret;
 
 	reg = ioread32(wdt_base + WDT_MODE);
-	reg &= ~(WDT_MODE_IRQ_EN | WDT_MODE_DUAL_EN);
+	reg &= ~WDT_MODE_IRQ_EN;
+	if (wdt_dev->pretimeout)
+		reg |= WDT_MODE_IRQ_EN;
+	else
+		reg &= ~WDT_MODE_IRQ_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)
+{
+	wdd->pretimeout = timeout;
+	return mtk_wdt_start(wdd);
+}
+
+static irqreturn_t mtk_wdt_isr(int irq, void *arg)
+{
+	struct watchdog_device *wdd = arg;
+	struct mtk_wdt_dev *mtk_wdt = watchdog_get_drvdata(wdd);
+	void __iomem *wdt_base = mtk_wdt->wdt_base;
+
+	watchdog_notify_pretimeout(wdd);
+	/*
+	 * Guaranteed to be reset when the timeout
+	 * expires under any situations
+	 */
+	mdelay(1000*wdd->pretimeout);
+	writel(WDT_SWRST_KEY, wdt_base + WDT_SWRST);
+
+	return IRQ_HANDLED;
+}
+
 static const struct watchdog_info mtk_wdt_info = {
 	.identity	= DRV_NAME,
 	.options	= WDIOF_SETTIMEOUT |
@@ -253,12 +282,21 @@ 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 +305,7 @@ 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 +317,22 @@ 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 = 1;
+	} 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;
@@ -360,7 +413,6 @@ static struct platform_driver mtk_wdt_driver = {
 };
 
 module_platform_driver(mtk_wdt_driver);
-
 module_param(timeout, uint, 0);
 MODULE_PARM_DESC(timeout, "Watchdog heartbeat in seconds");
 
-- 
2.7.4