linux-kernel - [PATCH 7/10] watchdog: bcm63xx_wdt: Add get

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Message-ID: <5651CC90.7090402@simon.arlott.org.uk>
Date:	Sun, 22 Nov 2015 14:09:20 +0000
From:	Simon Arlott <simon@...e.lp0.eu>
To:	Guenter Roeck <linux@...ck-us.net>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	Ralf Baechle <ralf@...ux-mips.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Jason Cooper <jason@...edaemon.net>,
	Marc Zyngier <marc.zyngier@....com>,
	Kevin Cernekee <cernekee@...il.com>,
	Florian Fainelli <f.fainelli@...il.com>,
	Wim Van Sebroeck <wim@...ana.be>,
	Maxime Bizon <mbizon@...ebox.fr>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-mips@...ux-mips.org, linux-watchdog@...r.kernel.org
Cc:	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>,
	Jonas Gorski <jogo@...nwrt.org>
Subject: [PATCH 7/10] watchdog: bcm63xx_wdt: Add get_timeleft function

Return the remaining time from the hardware control register.

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 | 38 +++++++++++++++++++++++++++++++++++++-
 1 file changed, 37 insertions(+), 1 deletion(-)

diff --git a/drivers/watchdog/bcm63xx_wdt.c b/drivers/watchdog/bcm63xx_wdt.c
index eb5e551..7109eb4 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>
@@ -75,6 +76,19 @@ static int bcm63xx_wdt_stop(struct watchdog_device *wdd)
 	return 0;
 }
 
+static unsigned int bcm63xx_wdt_get_timeleft(struct watchdog_device *wdd)
+{
+	struct bcm63xx_wdt_hw *hw = watchdog_get_drvdata(wdd);
+	unsigned long flags;
+	u32 val;
+
+	raw_spin_lock_irqsave(&hw->lock, flags);
+	val = __raw_readl(hw->regs + WDT_CTL_REG);
+	val /= hw->clock_hz;
+	raw_spin_unlock_irqrestore(&hw->lock, flags);
+	return val;
+}
+
 static int bcm63xx_wdt_set_timeout(struct watchdog_device *wdd,
 	unsigned int timeout)
 {
@@ -130,6 +144,7 @@ static struct watchdog_ops bcm63xx_wdt_ops = {
 	.owner = THIS_MODULE,
 	.start = bcm63xx_wdt_start,
 	.stop = bcm63xx_wdt_stop,
+	.get_timeleft = bcm63xx_wdt_get_timeleft,
 	.set_timeout = bcm63xx_wdt_set_timeout,
 };
 
@@ -144,6 +159,8 @@ 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);
@@ -182,7 +199,6 @@ 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;
@@ -197,6 +213,23 @@ 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 = bcm63xx_timer_register(TIMER_WDT_ID, bcm63xx_wdt_isr, wdd);
 	if (ret < 0) {
 		dev_err(&pdev->dev, "failed to register wdt timer isr\n");
@@ -214,6 +247,8 @@ static int bcm63xx_wdt_probe(struct platform_device *pdev)
 		dev_name(wdd->dev), hw->regs,
 		wdd->timeout, wdd->max_timeout);
 
+	if (timeleft > 0)
+		dev_alert(wdd->dev, "running, reboot in %us\n", timeleft);
 	return 0;
 
 unregister_timer:
@@ -255,6 +290,7 @@ module_platform_driver(bcm63xx_wdt_driver);
 
 MODULE_AUTHOR("Miguel Gaio <miguel.gaio@...xo.com>");
 MODULE_AUTHOR("Florian Fainelli <florian@...nwrt.org>");
+MODULE_AUTHOR("Simon Arlott");
 MODULE_DESCRIPTION("Driver for the Broadcom BCM63xx SoC watchdog");
 MODULE_LICENSE("GPL");
 MODULE_ALIAS("platform:bcm63xx-wdt");
-- 
2.1.4

-- 
Simon Arlott
--
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