Subject: [PATCH v2 2/2] watchdog: dw_wdt: add restart handler support

From: [email-masked] (Jisheng Zhang)
Date: Wed, 24 Sep 2014 09:11:01 +0800

Dear Guenter,

On Tue, 23 Sep 2014 11:31:59 -0700
Guenter Roeck <[email-masked]> wrote:

> On Tue, Sep 23, 2014 at 03:42:12PM +0800, Jisheng Zhang wrote:
> > The kernel core now provides an API to trigger a system restart.
> > Register with it to support restarting the system via. watchdog.
> > 
> > Signed-off-by: Jisheng Zhang <[email-masked]>
> > ---
> >  drivers/watchdog/dw_wdt.c | 32 ++++++++++++++++++++++++++++++++
> >  1 file changed, 32 insertions(+)
> > 
> > diff --git a/drivers/watchdog/dw_wdt.c b/drivers/watchdog/dw_wdt.c
> > index 449c885..9e577a6 100644
> > --- a/drivers/watchdog/dw_wdt.c
> > +++ b/drivers/watchdog/dw_wdt.c
> > @@ -21,6 +21,7 @@
> >  
> >  #include <linux/bitops.h>
> >  #include <linux/clk.h>
> > +#include <linux/delay.h>
> >  #include <linux/device.h>
> >  #include <linux/err.h>
> >  #include <linux/fs.h>
> > @@ -29,9 +30,11 @@
> >  #include <linux/miscdevice.h>
> >  #include <linux/module.h>
> >  #include <linux/moduleparam.h>
> > +#include <linux/notifier.h>
> >  #include <linux/of.h>
> >  #include <linux/pm.h>
> >  #include <linux/platform_device.h>
> > +#include <linux/reboot.h>
> >  #include <linux/spinlock.h>
> >  #include <linux/timer.h>
> >  #include <linux/uaccess.h>
> > @@ -63,6 +66,7 @@ static struct {
> >  	unsigned long		next_heartbeat;
> >  	struct timer_list	timer;
> >  	int			expect_close;
> > +	struct notifier_block	restart_handler;
> >  } dw_wdt;
> >  
> >  static inline int dw_wdt_is_enabled(void)
> > @@ -121,6 +125,26 @@ static void dw_wdt_keepalive(void)
> >  	       WDOG_COUNTER_RESTART_REG_OFFSET);
> >  }
> >  
> > +static int dw_wdt_restart_handle(struct notifier_block *this,
> > +				unsigned long mode, void *cmd)
> > +{
> > +	u32 val;
> > +
> > +	writel(0, dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
> > +	val = readl(dw_wdt.regs + WDOG_CONTROL_REG_OFFSET);
> > +	if (val & WDOG_CONTROL_REG_WDT_EN_MASK)
> > +		writel(WDOG_COUNTER_RESTART_KICK_VALUE, dw_wdt.regs +
> > +			WDOG_COUNTER_RESTART_REG_OFFSET);
> > +	else
> > +		writel(WDOG_CONTROL_REG_WDT_EN_MASK,
> > +		       dw_wdt.regs + WDOG_CONTROL_REG_OFFSET);
> > +
> > +	/* wait for reset to assert... */
> > +	mdelay(500);
> > +
> > +	return NOTIFY_DONE;
> > +}
> > +
> >  static void dw_wdt_ping(unsigned long data)
> >  {
> >  	if (time_before(jiffies, dw_wdt.next_heartbeat) ||
> > @@ -316,6 +340,12 @@ static int dw_wdt_drv_probe(struct platform_device
> > *pdev) if (ret)
> >  		goto out_disable_clk;
> >  
> > +	dw_wdt.restart_handler.notifier_call = dw_wdt_restart_handle;
> > +	dw_wdt.restart_handler.priority = 128;
> > +	ret = register_restart_handler(&dw_wdt.restart_handler);
> > +	if (ret)
> > +		pr_warn("cannot register restart handler\n");
> 
> Please use dev_warn(&pdev->dev, ...).

Yep, that's what I thought when patching the code. But the original source is
using pr_*(), so I use pr_warn() to keep unification. Is there any better
solution?

Thanks for your review,
Jisheng

> 
> Thanks,
> Guenter
> 
> > +
> >  	dw_wdt_set_next_heartbeat();
> >  	setup_timer(&dw_wdt.timer, dw_wdt_ping, 0);
> >  	mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);
> > @@ -330,6 +360,8 @@ out_disable_clk:
> >  
> >  static int dw_wdt_drv_remove(struct platform_device *pdev)
> >  {
> > +	unregister_restart_handler(&dw_wdt.restart_handler);
> > +
> >  	misc_deregister(&dw_wdt_miscdev);
> >  
> >  	clk_disable_unprepare(dw_wdt.clk);
> > -- 
> > 2.1.0
> > 
> > --
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