Subject: Re: [PATCH v2] watchdog: mpc8xxx_wdt convert to watchdog core

From: Guenter Roeck <[email-masked]>
Date: Tue, 03 Dec 2013 21:10:14 -0800

On 12/03/2013 05:31 AM, Christophe Leroy wrote:
> Convert mpc8xxx_wdt.c to the new watchdog API.
>
> Signed-off-by: Christophe Leroy <[email-masked]>
>
> diff -ur a/drivers/watchdog/mpc8xxx_wdt.c b/drivers/watchdog/mpc8xxx_wdt.c
> --- a/drivers/watchdog/mpc8xxx_wdt.c	2013-05-11 22:57:46.000000000 +0200
> +++ b/drivers/watchdog/mpc8xxx_wdt.c	2013-11-30 16:14:53.803495472 +0100
> @@ -72,53 +72,36 @@
>    * to 0
>    */
>   static int prescale = 1;
> -static unsigned int timeout_sec;
>
> -static unsigned long wdt_is_open;
>   static DEFINE_SPINLOCK(wdt_spinlock);
>
> -static void mpc8xxx_wdt_keepalive(void)
> +static int mpc8xxx_wdt_ping(struct watchdog_device *w)
>   {
>   	/* Ping the WDT */
>   	spin_lock(&wdt_spinlock);
>   	out_be16(&wd_base->swsrr, 0x556c);
>   	out_be16(&wd_base->swsrr, 0xaa39);
>   	spin_unlock(&wdt_spinlock);
> +	return 0;
>   }
>

Ok, now I understand a bit better.

I think it would be better to keep the original mpc8xxx_wdt_keepalive()
function and add

static int mpc8xxx_wdt_ping(struct watchdog_device *w)
{
	mpc8xxx_wdt_keepalive();
}

since the parameter is not used. Then you can call mpc8xxx_wdt_keepalive()
from mpc8xxx_wdt_timer_ping(), and you don't have to add the dummy argument.

Otherwise looks good.

Note there is a problem in the probe function with
	u32 freq = fsl_get_sys_freq();
and
	if (!freq || freq == -1)
		     ^^^^^^^^^^^

but fixing that would be a different patch.	

Guenter

> +static struct watchdog_device mpc8xxx_wdt_dev;
>   static void mpc8xxx_wdt_timer_ping(unsigned long arg);
> -static DEFINE_TIMER(wdt_timer, mpc8xxx_wdt_timer_ping, 0, 0);
> +static DEFINE_TIMER(wdt_timer, mpc8xxx_wdt_timer_ping, 0,
> +		(unsigned long)&mpc8xxx_wdt_dev);
>
>   static void mpc8xxx_wdt_timer_ping(unsigned long arg)
>   {
> -	mpc8xxx_wdt_keepalive();
> -	/* We're pinging it twice faster than needed, just to be sure. */
> -	mod_timer(&wdt_timer, jiffies + HZ * timeout_sec / 2);
> -}
> +	struct watchdog_device *w = (struct watchdog_device *)arg;
>
> -static void mpc8xxx_wdt_pr_warn(const char *msg)
> -{
> -	pr_crit("%s, expect the %s soon!\n", msg,
> -		reset ? "reset" : "machine check exception");
> -}
> -
> -static ssize_t mpc8xxx_wdt_write(struct file *file, const char __user *buf,
> -				 size_t count, loff_t *ppos)
> -{
> -	if (count)
> -		mpc8xxx_wdt_keepalive();
> -	return count;
> +	mpc8xxx_wdt_ping(w);
> +	/* We're pinging it twice faster than needed, just to be sure. */
> +	mod_timer(&wdt_timer, jiffies + HZ * w->timeout / 2);
>   }
>
> -static int mpc8xxx_wdt_open(struct inode *inode, struct file *file)
> +static int mpc8xxx_wdt_start(struct watchdog_device *w)
>   {
>   	u32 tmp = SWCRR_SWEN;
> -	if (test_and_set_bit(0, &wdt_is_open))
> -		return -EBUSY;
> -
> -	/* Once we start the watchdog we can't stop it */
> -	if (nowayout)
> -		__module_get(THIS_MODULE);
>
>   	/* Good, fire up the show */
>   	if (prescale)
> @@ -132,59 +115,31 @@
>
>   	del_timer_sync(&wdt_timer);
>
> -	return nonseekable_open(inode, file);
> +	return 0;
>   }
>
> -static int mpc8xxx_wdt_release(struct inode *inode, struct file *file)
> +static int mpc8xxx_wdt_stop(struct watchdog_device *w)
>   {
> -	if (!nowayout)
> -		mpc8xxx_wdt_timer_ping(0);
> -	else
> -		mpc8xxx_wdt_pr_warn("watchdog closed");
> -	clear_bit(0, &wdt_is_open);
> +	mod_timer(&wdt_timer, jiffies);
>   	return 0;
>   }
>
> -static long mpc8xxx_wdt_ioctl(struct file *file, unsigned int cmd,
> -							unsigned long arg)
> -{
> -	void __user *argp = (void __user *)arg;
> -	int __user *p = argp;
> -	static const struct watchdog_info ident = {
> -		.options = WDIOF_KEEPALIVEPING,
> -		.firmware_version = 1,
> -		.identity = "MPC8xxx",
> -	};
> -
> -	switch (cmd) {
> -	case WDIOC_GETSUPPORT:
> -		return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
> -	case WDIOC_GETSTATUS:
> -	case WDIOC_GETBOOTSTATUS:
> -		return put_user(0, p);
> -	case WDIOC_KEEPALIVE:
> -		mpc8xxx_wdt_keepalive();
> -		return 0;
> -	case WDIOC_GETTIMEOUT:
> -		return put_user(timeout_sec, p);
> -	default:
> -		return -ENOTTY;
> -	}
> -}
> +static struct watchdog_info mpc8xxx_wdt_info = {
> +	.options = WDIOF_KEEPALIVEPING,
> +	.firmware_version = 1,
> +	.identity = "MPC8xxx",
> +};
>
> -static const struct file_operations mpc8xxx_wdt_fops = {
> -	.owner		= THIS_MODULE,
> -	.llseek		= no_llseek,
> -	.write		= mpc8xxx_wdt_write,
> -	.unlocked_ioctl	= mpc8xxx_wdt_ioctl,
> -	.open		= mpc8xxx_wdt_open,
> -	.release	= mpc8xxx_wdt_release,
> +static struct watchdog_ops mpc8xxx_wdt_ops = {
> +	.owner = THIS_MODULE,
> +	.start = mpc8xxx_wdt_start,
> +	.ping = mpc8xxx_wdt_ping,
> +	.stop = mpc8xxx_wdt_stop,
>   };
>
> -static struct miscdevice mpc8xxx_wdt_miscdev = {
> -	.minor	= WATCHDOG_MINOR,
> -	.name	= "watchdog",
> -	.fops	= &mpc8xxx_wdt_fops,
> +static struct watchdog_device mpc8xxx_wdt_dev = {
> +	.info = &mpc8xxx_wdt_info,
> +	.ops = &mpc8xxx_wdt_ops,
>   };
>
>   static const struct of_device_id mpc8xxx_wdt_match[];
> @@ -196,6 +151,7 @@
>   	const struct mpc8xxx_wdt_type *wdt_type;
>   	u32 freq = fsl_get_sys_freq();
>   	bool enabled;
> +	unsigned int timeout_sec;
>
>   	match = of_match_device(mpc8xxx_wdt_match, &ofdev->dev);
>   	if (!match)
> @@ -222,6 +178,7 @@
>   	else
>   		timeout_sec = timeout / freq;
>
> +	mpc8xxx_wdt_dev.timeout = timeout_sec;
>   #ifdef MODULE
>   	ret = mpc8xxx_wdt_init_late();
>   	if (ret)
> @@ -237,7 +194,7 @@
>   	 * userspace handles it.
>   	 */
>   	if (enabled)
> -		mpc8xxx_wdt_timer_ping(0);
> +		mod_timer(&wdt_timer, jiffies);
>   	return 0;
>   err_unmap:
>   	iounmap(wd_base);
> @@ -247,9 +204,10 @@
>
>   static int mpc8xxx_wdt_remove(struct platform_device *ofdev)
>   {
> -	mpc8xxx_wdt_pr_warn("watchdog removed");
> +	pr_crit("Watchdog removed, expect the %s soon!\n",
> +		reset ? "reset" : "machine check exception");
>   	del_timer_sync(&wdt_timer);
> -	misc_deregister(&mpc8xxx_wdt_miscdev);
> +	watchdog_unregister_device(&mpc8xxx_wdt_dev);
>   	iounmap(wd_base);
>
>   	return 0;
> @@ -301,10 +259,11 @@
>   	if (!wd_base)
>   		return -ENODEV;
>
> -	ret = misc_register(&mpc8xxx_wdt_miscdev);
> +	watchdog_set_nowayout(&mpc8xxx_wdt_dev, nowayout);
> +
> +	ret = watchdog_register_device(&mpc8xxx_wdt_dev);
>   	if (ret) {
> -		pr_err("cannot register miscdev on minor=%d (err=%d)\n",
> -		       WATCHDOG_MINOR, ret);
> +		pr_err("cannot register watchdog device (err=%d)\n", ret);
>   		return ret;
>   	}
>   	return 0;
> diff -ur a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -1146,6 +1146,7 @@
>   config 8xxx_WDT
>   	tristate "MPC8xxx Platform Watchdog Timer"
>   	depends on PPC_8xx || PPC_83xx || PPC_86xx
> +	select WATCHDOG_CORE
>   	help
>   	  This driver is for a SoC level watchdog that exists on some
>   	  Freescale PowerPC processors. So far this driver supports:
>
>