linux-kernel - [PATCH 08/11] watchdog: bcm63xx_wdt: Warn if the watchdog is currently running

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Message-ID: <565D9BE9.4060008@simon.arlott.org.uk>
Date:	Tue, 1 Dec 2015 13:08:57 +0000
From:	Simon Arlott <simon@...e.lp0.eu>
To:	Guenter Roeck <linux@...ck-us.net>,
	Thomas Gleixner <tglx@...utronix.de>
Cc:	Florian Fainelli <f.fainelli@...il.com>,
	MIPS Mailing List <linux-mips@...ux-mips.org>,
	Jonas Gorski <jogo@...nwrt.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	Ralf Baechle <ralf@...ux-mips.org>,
	Jason Cooper <jason@...edaemon.net>,
	Marc Zyngier <marc.zyngier@....com>,
	Kevin Cernekee <cernekee@...il.com>,
	Wim Van Sebroeck <wim@...ana.be>,
	Maxime Bizon <mbizon@...ebox.fr>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-watchdog@...r.kernel.org, Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>
Subject: [PATCH 08/11] watchdog: bcm63xx_wdt: Warn if the watchdog is
 currently running

Warn when the device is registered if the hardware watchdog is currently
running and report the remaining time left.

Signed-off-by: Simon Arlott <simon@...e.lp0.eu>
---
 drivers/watchdog/bcm63xx_wdt.c | 23 ++++++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/drivers/watchdog/bcm63xx_wdt.c b/drivers/watchdog/bcm63xx_wdt.c
index ab4a794..2312dc2 100644
--- a/drivers/watchdog/bcm63xx_wdt.c
+++ b/drivers/watchdog/bcm63xx_wdt.c
@@ -14,6 +14,7 @@
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #include <linux/clk.h>
+#include <linux/delay.h>
 #include <linux/errno.h>
 #include <linux/io.h>
 #include <linux/kernel.h>
@@ -159,6 +160,8 @@ static int bcm63xx_wdt_probe(struct platform_device *pdev)
 	struct bcm63xx_wdt_hw *hw;
 	struct watchdog_device *wdd;
 	struct resource *r;
+	u32 timeleft1, timeleft2;
+	unsigned int timeleft;
 	int ret;
 
 	hw = devm_kzalloc(&pdev->dev, sizeof(*hw), GFP_KERNEL);
@@ -199,7 +202,6 @@ static int bcm63xx_wdt_probe(struct platform_device *pdev)
 	}
 
 	raw_spin_lock_init(&hw->lock);
-	hw->running = false;
 
 	wdd->parent = &pdev->dev;
 	wdd->ops = &bcm63xx_wdt_ops;
@@ -213,6 +215,23 @@ static int bcm63xx_wdt_probe(struct platform_device *pdev)
 	watchdog_init_timeout(wdd, 0, &pdev->dev);
 	watchdog_set_nowayout(wdd, nowayout);
 
+	/* Compare two reads of the time left value, 2 clock ticks apart */
+	rmb();
+	timeleft1 = __raw_readl(hw->regs + WDT_CTL_REG);
+	udelay(DIV_ROUND_UP(1000000, hw->clock_hz / 2));
+	/* Ensure the register is read twice */
+	rmb();
+	timeleft2 = __raw_readl(hw->regs + WDT_CTL_REG);
+
+	/* If the time left is changing, the watchdog is running */
+	if (timeleft1 != timeleft2) {
+		hw->running = true;
+		timeleft = bcm63xx_wdt_get_timeleft(wdd);
+	} else {
+		hw->running = false;
+		timeleft = 0;
+	}
+
 	ret = watchdog_register_device(wdd);
 	if (ret < 0) {
 		dev_err(&pdev->dev, "failed to register watchdog device\n");
@@ -230,6 +249,8 @@ static int bcm63xx_wdt_probe(struct platform_device *pdev)
 		dev_name(wdd->dev), hw->regs,
 		wdd->timeout, wdd->max_timeout);
 
+	if (hw->running)
+		dev_alert(wdd->dev, "running, reboot in %us\n", timeleft);
 	return 0;
 
 unregister_watchdog:
-- 
2.1.4


-- 
Simon Arlott
--
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