Message-ID: <20160118125525.2163fa0d@xhacker>
Date:	Mon, 18 Jan 2016 12:55:25 +0800
From:	Jisheng Zhang <jszhang@...vell.com>
To:	Guenter Roeck <linux@...ck-us.net>
CC:	<wim@...ana.be>, <sebastian.hesselbarth@...il.com>,
	<linux-watchdog@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] watchdog: dw_wdt: convert to watchdog core api

On Sun, 17 Jan 2016 09:30:28 -0800 Guenter Roeck wrote:

> On 12/16/2015 02:27 AM, Jisheng Zhang wrote:
> > Convert the dw_wdt driver to the new watchdog core api.
> >
> > Signed-off-by: Jisheng Zhang <jszhang@...vell.com>
> > ---
> > This patch depends on the signedness bug fix patch:
> > http://lists.infradead.org/pipermail/linux-arm-kernel/2015-December/393872.html
> >  
> 
> Hi,
> 
> sorry for not getting back earlier.
> 
> I have a similar patch pending, but it depends on watchdog core changes which
> are still being worked on. Hopefully those changes, together with the reworked
> dw_wdt driver, can make it into 4.6.

oops, I didn't notice that. Glad to know there's already a patch for it.
Waiting for the merging ;)

Thanks a lot,
Jisheng

> 
> Thanks,
> Guenter
> 
> 
> >   drivers/watchdog/Kconfig  |   1 +
> >   drivers/watchdog/dw_wdt.c | 316 +++++++++++++++++++---------------------------
> >   2 files changed, 131 insertions(+), 186 deletions(-)
> >
> > diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> > index 7a8a6c6..886468a 100644
> > --- a/drivers/watchdog/Kconfig
> > +++ b/drivers/watchdog/Kconfig
> > @@ -291,6 +291,7 @@ config SA1100_WATCHDOG
> >   config DW_WATCHDOG
> >   	tristate "Synopsys DesignWare watchdog"
> >   	depends on HAS_IOMEM
> > +	select WATCHDOG_CORE
> >   	help
> >   	  Say Y here if to include support for the Synopsys DesignWare
> >   	  watchdog timer found in many chips.
> > diff --git a/drivers/watchdog/dw_wdt.c b/drivers/watchdog/dw_wdt.c
> > index 8fefa4ad..9e8706a 100644
> > --- a/drivers/watchdog/dw_wdt.c
> > +++ b/drivers/watchdog/dw_wdt.c
> > @@ -24,10 +24,8 @@
> >   #include <linux/delay.h>
> >   #include <linux/device.h>
> >   #include <linux/err.h>
> > -#include <linux/fs.h>
> >   #include <linux/io.h>
> >   #include <linux/kernel.h>
> > -#include <linux/miscdevice.h>
> >   #include <linux/module.h>
> >   #include <linux/moduleparam.h>
> >   #include <linux/notifier.h>
> > @@ -36,7 +34,6 @@
> >   #include <linux/platform_device.h>
> >   #include <linux/reboot.h>
> >   #include <linux/timer.h>
> > -#include <linux/uaccess.h>
> >   #include <linux/watchdog.h>
> >
> >   #define WDOG_CONTROL_REG_OFFSET		    0x00
> > @@ -59,59 +56,60 @@ MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
> >
> >   #define WDT_TIMEOUT		(HZ / 2)
> >
> > -static struct {
> > +struct dw_wdt_device {
> >   	void __iomem		*regs;
> >   	struct clk		*clk;
> > -	unsigned long		in_use;
> > -	unsigned long		next_heartbeat;
> >   	struct timer_list	timer;
> > -	int			expect_close;
> > +	struct watchdog_device	wdog;
> >   	struct notifier_block	restart_handler;
> > -} dw_wdt;
> > +};
> >
> > -static inline int dw_wdt_is_enabled(void)
> > +static inline bool dw_wdt_is_enabled(struct dw_wdt_device *wdev)
> >   {
> > -	return readl(dw_wdt.regs + WDOG_CONTROL_REG_OFFSET) &
> > +	return readl(wdev->regs + WDOG_CONTROL_REG_OFFSET) &
> >   		WDOG_CONTROL_REG_WDT_EN_MASK;
> >   }
> >
> > -static inline int dw_wdt_top_in_seconds(unsigned top)
> > +static inline unsigned int dw_wdt_top_in_seconds(struct dw_wdt_device *wdev,
> > +						 unsigned int top)
> >   {
> >   	/*
> >   	 * There are 16 possible timeout values in 0..15 where the number of
> >   	 * cycles is 2 ^ (16 + i) and the watchdog counts down.
> >   	 */
> > -	return (1U << (16 + top)) / clk_get_rate(dw_wdt.clk);
> > +	return (1U << (16 + top)) / clk_get_rate(wdev->clk);
> >   }
> >
> > -static int dw_wdt_get_top(void)
> > +static unsigned int dw_wdt_get_timeleft(struct watchdog_device *wdog)
> >   {
> > -	int top = readl(dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET) & 0xF;
> > +	struct dw_wdt_device *wdev = watchdog_get_drvdata(wdog);
> >
> > -	return dw_wdt_top_in_seconds(top);
> > +	return readl(wdev->regs + WDOG_CURRENT_COUNT_REG_OFFSET) /
> > +		clk_get_rate(wdev->clk);
> >   }
> >
> > -static inline void dw_wdt_set_next_heartbeat(void)
> > +static int dw_wdt_ping(struct watchdog_device *wdog)
> >   {
> > -	dw_wdt.next_heartbeat = jiffies + dw_wdt_get_top() * HZ;
> > -}
> > +	struct dw_wdt_device *wdev = watchdog_get_drvdata(wdog);
> >
> > -static void dw_wdt_keepalive(void)
> > -{
> > -	writel(WDOG_COUNTER_RESTART_KICK_VALUE, dw_wdt.regs +
> > +	writel(WDOG_COUNTER_RESTART_KICK_VALUE, wdev->regs +
> >   	       WDOG_COUNTER_RESTART_REG_OFFSET);
> > +
> > +	return 0;
> >   }
> >
> > -static int dw_wdt_set_top(unsigned top_s)
> > +static int dw_wdt_set_timeout(struct watchdog_device *wdog,
> > +			      unsigned int new_timeout)
> >   {
> > -	int i, top_val = DW_WDT_MAX_TOP;
> > +	unsigned int i, top_val = DW_WDT_MAX_TOP;
> > +	struct dw_wdt_device *wdev = watchdog_get_drvdata(wdog);
> >
> >   	/*
> >   	 * Iterate over the timeout values until we find the closest match. We
> >   	 * always look for >=.
> >   	 */
> >   	for (i = 0; i <= DW_WDT_MAX_TOP; ++i)
> > -		if (dw_wdt_top_in_seconds(i) >= top_s) {
> > +		if (dw_wdt_top_in_seconds(wdev, i) >= new_timeout) {
> >   			top_val = i;
> >   			break;
> >   		}
> > @@ -123,33 +121,34 @@ static int dw_wdt_set_top(unsigned top_s)
> >   	 * effectively get a pat of the watchdog right here.
> >   	 */
> >   	writel(top_val | top_val << WDOG_TIMEOUT_RANGE_TOPINIT_SHIFT,
> > -		dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
> > +		wdev->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
> >
> >   	/*
> >   	 * Add an explicit pat to handle versions of the watchdog that
> >   	 * don't have TOPINIT.  This won't hurt on versions that have
> >   	 * it.
> >   	 */
> > -	dw_wdt_keepalive();
> > -
> > -	dw_wdt_set_next_heartbeat();
> > +	dw_wdt_ping(wdog);
> >
> > -	return dw_wdt_top_in_seconds(top_val);
> > +	return 0;
> >   }
> >
> >   static int dw_wdt_restart_handle(struct notifier_block *this,
> >   				unsigned long mode, void *cmd)
> >   {
> >   	u32 val;
> > +	struct dw_wdt_device *wdev = container_of(this,
> > +						  struct dw_wdt_device,
> > +						  restart_handler);
> >
> > -	writel(0, dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
> > -	val = readl(dw_wdt.regs + WDOG_CONTROL_REG_OFFSET);
> > +	writel(0, wdev->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
> > +	val = readl(wdev->regs + WDOG_CONTROL_REG_OFFSET);
> >   	if (val & WDOG_CONTROL_REG_WDT_EN_MASK)
> > -		writel(WDOG_COUNTER_RESTART_KICK_VALUE, dw_wdt.regs +
> > +		writel(WDOG_COUNTER_RESTART_KICK_VALUE, wdev->regs +
> >   			WDOG_COUNTER_RESTART_REG_OFFSET);
> >   	else
> >   		writel(WDOG_CONTROL_REG_WDT_EN_MASK,
> > -		       dw_wdt.regs + WDOG_CONTROL_REG_OFFSET);
> > +		       wdev->regs + WDOG_CONTROL_REG_OFFSET);
> >
> >   	/* wait for reset to assert... */
> >   	mdelay(500);
> > @@ -157,74 +156,52 @@ static int dw_wdt_restart_handle(struct notifier_block *this,
> >   	return NOTIFY_DONE;
> >   }
> >
> > -static void dw_wdt_ping(unsigned long data)
> > +static void dw_wdt_timer_ping(unsigned long arg)
> >   {
> > -	if (time_before(jiffies, dw_wdt.next_heartbeat) ||
> > -	    (!nowayout && !dw_wdt.in_use)) {
> > -		dw_wdt_keepalive();
> > -		mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);
> > -	} else
> > -		pr_crit("keepalive missed, machine will reset\n");
> > +	struct watchdog_device *wdog = (struct watchdog_device *)arg;
> > +	struct dw_wdt_device *wdev = watchdog_get_drvdata(wdog);
> > +
> > +	/* ping it every wdog->timeout / 2 seconds to prevent reboot */
> > +	dw_wdt_ping(wdog);
> > +	mod_timer(&wdev->timer, jiffies + wdog->timeout * HZ / 2);
> >   }
> >
> > -static int dw_wdt_open(struct inode *inode, struct file *filp)
> > +static int dw_wdt_start(struct watchdog_device *wdog)
> >   {
> > -	if (test_and_set_bit(0, &dw_wdt.in_use))
> > -		return -EBUSY;
> > -
> > -	/* Make sure we don't get unloaded. */
> > -	__module_get(THIS_MODULE);
> > -
> > -	if (!dw_wdt_is_enabled()) {
> > -		/*
> > -		 * The watchdog is not currently enabled. Set the timeout to
> > -		 * something reasonable and then start it.
> > -		 */
> > -		dw_wdt_set_top(DW_WDT_DEFAULT_SECONDS);
> > +	struct dw_wdt_device *wdev = watchdog_get_drvdata(wdog);
> > +
> > +	if (!dw_wdt_is_enabled(wdev)) {
> > +		dw_wdt_set_timeout(wdog, wdog->timeout);
> >   		writel(WDOG_CONTROL_REG_WDT_EN_MASK,
> > -		       dw_wdt.regs + WDOG_CONTROL_REG_OFFSET);
> > +		       wdev->regs + WDOG_CONTROL_REG_OFFSET);
> > +	} else {
> > +		/* delete the timer that pings the watchdog after close */
> > +		del_timer_sync(&wdev->timer);
> > +		dw_wdt_set_timeout(wdog, wdog->timeout);
> >   	}
> >
> > -	dw_wdt_set_next_heartbeat();
> > -
> > -	return nonseekable_open(inode, filp);
> > +	return 0;
> >   }
> >
> > -static ssize_t dw_wdt_write(struct file *filp, const char __user *buf,
> > -			    size_t len, loff_t *offset)
> > +static int dw_wdt_stop(struct watchdog_device *wdog)
> >   {
> > -	if (!len)
> > -		return 0;
> > -
> > -	if (!nowayout) {
> > -		size_t i;
> > -
> > -		dw_wdt.expect_close = 0;
> > -
> > -		for (i = 0; i < len; ++i) {
> > -			char c;
> > -
> > -			if (get_user(c, buf + i))
> > -				return -EFAULT;
> > -
> > -			if (c == 'V') {
> > -				dw_wdt.expect_close = 1;
> > -				break;
> > -			}
> > -		}
> > -	}
> > -
> > -	dw_wdt_set_next_heartbeat();
> > -	dw_wdt_keepalive();
> > -	mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);
> > -
> > -	return len;
> > +	/*
> > +	 * We don't need a clk_disable_unprepare, the wdt cannot be disabled
> > +	 * once started. We use a timer to ping the watchdog while the
> > +	 * /dev/watchdog is closed
> > +	 */
> > +	dw_wdt_timer_ping((unsigned long)wdog);
> > +	return 0;
> >   }
> >
> > -static u32 dw_wdt_time_left(void)
> > +static inline void dw_wdt_ping_if_active(struct watchdog_device *wdog)
> >   {
> > -	return readl(dw_wdt.regs + WDOG_CURRENT_COUNT_REG_OFFSET) /
> > -		clk_get_rate(dw_wdt.clk);
> > +	struct dw_wdt_device *wdev = watchdog_get_drvdata(wdog);
> > +
> > +	if (dw_wdt_is_enabled(wdev)) {
> > +		dw_wdt_set_timeout(wdog, wdog->timeout);
> > +		dw_wdt_timer_ping((unsigned long)wdog);
> > +	}
> >   }
> >
> >   static const struct watchdog_info dw_wdt_ident = {
> > @@ -233,78 +210,37 @@ static const struct watchdog_info dw_wdt_ident = {
> >   	.identity	= "Synopsys DesignWare Watchdog",
> >   };
> >
> > -static long dw_wdt_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> > -{
> > -	unsigned long val;
> > -	int timeout;
> > -
> > -	switch (cmd) {
> > -	case WDIOC_GETSUPPORT:
> > -		return copy_to_user((void __user *)arg, &dw_wdt_ident,
> > -				    sizeof(dw_wdt_ident)) ? -EFAULT : 0;
> > -
> > -	case WDIOC_GETSTATUS:
> > -	case WDIOC_GETBOOTSTATUS:
> > -		return put_user(0, (int __user *)arg);
> > -
> > -	case WDIOC_KEEPALIVE:
> > -		dw_wdt_set_next_heartbeat();
> > -		return 0;
> > -
> > -	case WDIOC_SETTIMEOUT:
> > -		if (get_user(val, (int __user *)arg))
> > -			return -EFAULT;
> > -		timeout = dw_wdt_set_top(val);
> > -		return put_user(timeout , (int __user *)arg);
> > -
> > -	case WDIOC_GETTIMEOUT:
> > -		return put_user(dw_wdt_get_top(), (int __user *)arg);
> > -
> > -	case WDIOC_GETTIMELEFT:
> > -		/* Get the time left until expiry. */
> > -		if (get_user(val, (int __user *)arg))
> > -			return -EFAULT;
> > -		return put_user(dw_wdt_time_left(), (int __user *)arg);
> > -
> > -	default:
> > -		return -ENOTTY;
> > -	}
> > -}
> > -
> > -static int dw_wdt_release(struct inode *inode, struct file *filp)
> > -{
> > -	clear_bit(0, &dw_wdt.in_use);
> > -
> > -	if (!dw_wdt.expect_close) {
> > -		del_timer(&dw_wdt.timer);
> > -
> > -		if (!nowayout)
> > -			pr_crit("unexpected close, system will reboot soon\n");
> > -		else
> > -			pr_crit("watchdog cannot be disabled, system will reboot soon\n");
> > -	}
> > -
> > -	dw_wdt.expect_close = 0;
> > -
> > -	return 0;
> > -}
> > +static const struct watchdog_ops dw_wdt_ops = {
> > +	.owner		= THIS_MODULE,
> > +	.start		= dw_wdt_start,
> > +	.stop		= dw_wdt_stop,
> > +	.ping		= dw_wdt_ping,
> > +	.set_timeout	= dw_wdt_set_timeout,
> > +	.get_timeleft	= dw_wdt_get_timeleft,
> > +};
> >
> >   #ifdef CONFIG_PM_SLEEP
> >   static int dw_wdt_suspend(struct device *dev)
> >   {
> > -	clk_disable_unprepare(dw_wdt.clk);
> > +	struct watchdog_device *wdog = dev_get_drvdata(dev);
> > +	struct dw_wdt_device *wdev = watchdog_get_drvdata(wdog);
> > +
> > +	clk_disable_unprepare(wdev->clk);
> >
> >   	return 0;
> >   }
> >
> >   static int dw_wdt_resume(struct device *dev)
> >   {
> > -	int err = clk_prepare_enable(dw_wdt.clk);
> > +	struct watchdog_device *wdog = dev_get_drvdata(dev);
> > +	struct dw_wdt_device *wdev = watchdog_get_drvdata(wdog);
> > +
> > +	int err = clk_prepare_enable(wdev->clk);
> >
> >   	if (err)
> >   		return err;
> >
> > -	dw_wdt_keepalive();
> > +	dw_wdt_ping(wdog);
> >
> >   	return 0;
> >   }
> > @@ -312,67 +248,75 @@ static int dw_wdt_resume(struct device *dev)
> >
> >   static SIMPLE_DEV_PM_OPS(dw_wdt_pm_ops, dw_wdt_suspend, dw_wdt_resume);
> >
> > -static const struct file_operations wdt_fops = {
> > -	.owner		= THIS_MODULE,
> > -	.llseek		= no_llseek,
> > -	.open		= dw_wdt_open,
> > -	.write		= dw_wdt_write,
> > -	.unlocked_ioctl	= dw_wdt_ioctl,
> > -	.release	= dw_wdt_release
> > -};
> > -
> > -static struct miscdevice dw_wdt_miscdev = {
> > -	.fops		= &wdt_fops,
> > -	.name		= "watchdog",
> > -	.minor		= WATCHDOG_MINOR,
> > -};
> > -
> >   static int dw_wdt_drv_probe(struct platform_device *pdev)
> >   {
> >   	int ret;
> > -	struct resource *mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > -
> > -	dw_wdt.regs = devm_ioremap_resource(&pdev->dev, mem);
> > -	if (IS_ERR(dw_wdt.regs))
> > -		return PTR_ERR(dw_wdt.regs);
> > -
> > -	dw_wdt.clk = devm_clk_get(&pdev->dev, NULL);
> > -	if (IS_ERR(dw_wdt.clk))
> > -		return PTR_ERR(dw_wdt.clk);
> > -
> > -	ret = clk_prepare_enable(dw_wdt.clk);
> > +	struct dw_wdt_device *wdev;
> > +	struct watchdog_device *wdog;
> > +	struct resource *mem;
> > +
> > +	wdev = devm_kzalloc(&pdev->dev, sizeof(*wdev), GFP_KERNEL);
> > +	if (!wdev)
> > +		return -ENOMEM;
> > +
> > +	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > +	wdev->regs = devm_ioremap_resource(&pdev->dev, mem);
> > +	if (IS_ERR(wdev->regs))
> > +		return PTR_ERR(wdev->regs);
> > +
> > +	wdev->clk = devm_clk_get(&pdev->dev, NULL);
> > +	if (IS_ERR(wdev->clk))
> > +		return PTR_ERR(wdev->clk);
> > +
> > +	wdog			= &wdev->wdog;
> > +	wdog->info		= &dw_wdt_ident;
> > +	wdog->ops		= &dw_wdt_ops;
> > +	wdog->min_timeout	= dw_wdt_top_in_seconds(wdev, 0);
> > +	wdog->max_timeout	= dw_wdt_top_in_seconds(wdev, DW_WDT_MAX_TOP);
> > +
> > +	ret = clk_prepare_enable(wdev->clk);
> >   	if (ret)
> >   		return ret;
> >
> > -	ret = misc_register(&dw_wdt_miscdev);
> > -	if (ret)
> > -		goto out_disable_clk;
> > +	platform_set_drvdata(pdev, wdog);
> > +	watchdog_set_drvdata(wdog, wdev);
> > +	watchdog_set_nowayout(wdog, nowayout);
> > +	watchdog_init_timeout(wdog, wdog->max_timeout, &pdev->dev);
> >
> > -	dw_wdt.restart_handler.notifier_call = dw_wdt_restart_handle;
> > -	dw_wdt.restart_handler.priority = 128;
> > -	ret = register_restart_handler(&dw_wdt.restart_handler);
> > +	wdev->restart_handler.notifier_call = dw_wdt_restart_handle;
> > +	wdev->restart_handler.priority = 128;
> > +	ret = register_restart_handler(&wdev->restart_handler);
> >   	if (ret)
> > -		pr_warn("cannot register restart handler\n");
> > +		dev_warn(&pdev->dev, "cannot register restart handler\n");
> >
> > -	dw_wdt_set_next_heartbeat();
> > -	setup_timer(&dw_wdt.timer, dw_wdt_ping, 0);
> > -	mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);
> > +	setup_timer(&wdev->timer, dw_wdt_timer_ping, (unsigned long)wdog);
> > +
> > +	dw_wdt_ping_if_active(wdog);
> > +
> > +	ret = watchdog_register_device(wdog);
> > +	if (ret) {
> > +		dev_err(&pdev->dev, "cannot register watchdog device\n");
> > +		goto out_disable_clk;
> > +	}
> >
> >   	return 0;
> >
> >   out_disable_clk:
> > -	clk_disable_unprepare(dw_wdt.clk);
> > +	clk_disable_unprepare(wdev->clk);
> >
> >   	return ret;
> >   }
> >
> >   static int dw_wdt_drv_remove(struct platform_device *pdev)
> >   {
> > -	unregister_restart_handler(&dw_wdt.restart_handler);
> > +	struct watchdog_device *wdog = platform_get_drvdata(pdev);
> > +	struct dw_wdt_device *wdev = watchdog_get_drvdata(wdog);
> > +
> > +	unregister_restart_handler(&wdev->restart_handler);
> >
> > -	misc_deregister(&dw_wdt_miscdev);
> > +	watchdog_unregister_device(wdog);
> >
> > -	clk_disable_unprepare(dw_wdt.clk);
> > +	clk_disable_unprepare(wdev->clk);
> >
> >   	return 0;
> >   }
> >  
> 

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