Re: [RFC PATCH v2] watchdog: ep93xx: Use the WatchDog Timer Driver Core.

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On Wed, Aug 03, 2011 at 10:21:26AM -0700, H Hartley Sweeten wrote:
> Convert the ep93xx watchdog driver to using the WatchDog Timer Driver Core.
> 
> Signed-off-by: H Hartley Sweeten <hsweeten@xxxxxxxxxxxxxxxxxxx>
> Cc: Wim Van Sebroeck <wim@xxxxxxxxx>
> Cc: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>

Tested-by: Mika Westerberg <mika.westerberg@xxxxxx>

BTW, now that the driver uses watchdog core should we also select
WATCHDOG_CORE in the Kconfig? If it is not enabled we get:

drivers/built-in.o: In function `ep93xx_wdt_init':
clkdev.c:(.init.text+0x2bd8): undefined reference to
`watchdog_register_device'
make: *** [.tmp_vmlinux1] Error 1

Other than that, you can also add my

Reviewed-by: Mika Westerberg <mika.westerberg@xxxxxx>

if you like.

> 
> ---
> 
> v2: use the pr_* functions instead of printk(KERN_* PFX
>     document the register magic numbers and bits
>     fold the register access functions into the callers
>     add WDIOF_KEEPALIVEPING to the options
>     fix the bootstatus use, any detected reset is reported as WDIOF_CARDRESET
>     add a boot message so the user can see what actually caused the reset
>     validate that the user's requested timeout is actually valid
>     fix a typo in the v1 patch (extra void in ep93xx_wdt_start)
>     fix ep93xx_wdt_exit, ep93xx_wdt_stop should be called not wdt_shutdown
> 
> diff --git a/drivers/watchdog/ep93xx_wdt.c b/drivers/watchdog/ep93xx_wdt.c
> index 726b7df..4309db3 100644
> --- a/drivers/watchdog/ep93xx_wdt.c
> +++ b/drivers/watchdog/ep93xx_wdt.c
> @@ -23,184 +23,102 @@
>   *	- Add a few missing ioctls
>   */
>  
> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> +
>  #include <linux/module.h>
> -#include <linux/fs.h>
>  #include <linux/miscdevice.h>
>  #include <linux/watchdog.h>
>  #include <linux/timer.h>
> -#include <linux/uaccess.h>
>  #include <linux/io.h>
>  #include <mach/hardware.h>
>  
>  #define WDT_VERSION	"0.3"
> -#define PFX		"ep93xx_wdt: "
>  
>  /* default timeout (secs) */
>  #define WDT_TIMEOUT 30
>  
>  static int nowayout = WATCHDOG_NOWAYOUT;
> +module_param(nowayout, int, 0);
> +MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
> +
>  static int timeout = WDT_TIMEOUT;
> +module_param(timeout, int, 0);
> +MODULE_PARM_DESC(timeout,
> +	"Watchdog timeout in seconds. (1<=timeout<=3600, default="
> +				__MODULE_STRING(WDT_TIMEOUT) ")");
>  
>  static struct timer_list timer;
>  static unsigned long next_heartbeat;
> -static unsigned long wdt_status;
> -static unsigned long boot_status;
> -
> -#define WDT_IN_USE		0
> -#define WDT_OK_TO_CLOSE		1
>  
>  #define EP93XX_WDT_REG(x)	(EP93XX_WATCHDOG_BASE + (x))
>  #define EP93XX_WDT_WATCHDOG	EP93XX_WDT_REG(0x00)
>  #define EP93XX_WDT_WDSTATUS	EP93XX_WDT_REG(0x04)
>  
> +/* Watchdog register write only values */
> +#define EP93XX_WATCHDOG_RESTART		0x5555
> +#define EP93XX_WATCHDOG_DISABLE		0xaa55
> +#define EP93XX_WATCHDOG_ENABLE		0xaaaa
> +
> +/* Watchdog register read only bits */
> +#define EP93XX_WATCHDOG_PLSDSN		(1 << 6)
> +#define EP93XX_WATCHDOG_OVRID		(1 << 5)
> +#define EP93XX_WATCHDOG_SWDIS		(1 << 4)
> +#define EP93XX_WATCHDOG_HWDIS		(1 << 3)
> +#define EP93XX_WATCHDOG_URST		(1 << 2)
> +#define EP93XX_WATCHDOG_3KRST		(1 << 1)
> +#define EP93XX_WATCHDOG_WD		(1 << 0)
> +#define EP93XX_WATCHDOG_RESET_MASK	(0x07)
> +
>  /* reset the wdt every ~200ms */
>  #define WDT_INTERVAL (HZ/5)
>  
> -static void wdt_enable(void)
> -{
> -	__raw_writew(0xaaaa, EP93XX_WDT_WATCHDOG);
> -}
> -
> -static void wdt_disable(void)
> +static int ep93xx_wdt_start(struct watchdog_device *wdd)
>  {
> -	__raw_writew(0xaa55, EP93XX_WDT_WATCHDOG);
> -}
> -
> -static inline void wdt_ping(void)
> -{
> -	__raw_writew(0x5555, EP93XX_WDT_WATCHDOG);
> -}
> +	next_heartbeat = jiffies + (wdd->timeout * HZ);
>  
> -static void wdt_startup(void)
> -{
> -	next_heartbeat = jiffies + (timeout * HZ);
> -
> -	wdt_enable();
> +	__raw_writew(EP93XX_WATCHDOG_ENABLE, EP93XX_WDT_WATCHDOG);
>  	mod_timer(&timer, jiffies + WDT_INTERVAL);
> +	return 0;
>  }
>  
> -static void wdt_shutdown(void)
> +static int ep93xx_wdt_stop(struct watchdog_device *wdd)
>  {
>  	del_timer_sync(&timer);
> -	wdt_disable();
> +	__raw_writew(EP93XX_WATCHDOG_DISABLE, EP93XX_WDT_WATCHDOG);
> +	return 0;
>  }
>  
> -static void wdt_keepalive(void)
> +static int ep93xx_wdt_keepalive(struct watchdog_device *wdd)
>  {
>  	/* user land ping */
> -	next_heartbeat = jiffies + (timeout * HZ);
> -}
> -
> -static int ep93xx_wdt_open(struct inode *inode, struct file *file)
> -{
> -	if (test_and_set_bit(WDT_IN_USE, &wdt_status))
> -		return -EBUSY;
> -
> -	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
> -
> -	wdt_startup();
> -
> -	return nonseekable_open(inode, file);
> -}
> -
> -static ssize_t
> -ep93xx_wdt_write(struct file *file, const char __user *data, size_t len,
> -		 loff_t *ppos)
> -{
> -	if (len) {
> -		if (!nowayout) {
> -			size_t i;
> -
> -			clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
> -
> -			for (i = 0; i != len; i++) {
> -				char c;
> -
> -				if (get_user(c, data + i))
> -					return -EFAULT;
> -
> -				if (c == 'V')
> -					set_bit(WDT_OK_TO_CLOSE, &wdt_status);
> -				else
> -					clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
> -			}
> -		}
> -		wdt_keepalive();
> -	}
> -
> -	return len;
> +	next_heartbeat = jiffies + (wdd->timeout * HZ);
> +	return 0;
>  }
>  
> -static const struct watchdog_info ident = {
> -	.options = WDIOF_CARDRESET | WDIOF_MAGICCLOSE,
> -	.identity = "EP93xx Watchdog",
> +static const struct watchdog_info ep93xx_wdt_ident = {
> +	.options	= WDIOF_CARDRESET | WDIOF_MAGICCLOSE |
> +			  WDIOF_KEEPALIVEPING,
> +	.identity	= "EP93xx Watchdog",
>  };
>  
> -static long ep93xx_wdt_ioctl(struct file *file,
> -					unsigned int cmd, unsigned long arg)
> -{
> -	int ret = -ENOTTY;
> -
> -	switch (cmd) {
> -	case WDIOC_GETSUPPORT:
> -		ret = copy_to_user((struct watchdog_info __user *)arg, &ident,
> -				sizeof(ident)) ? -EFAULT : 0;
> -		break;
> -
> -	case WDIOC_GETSTATUS:
> -		ret = put_user(0, (int __user *)arg);
> -		break;
> -
> -	case WDIOC_GETBOOTSTATUS:
> -		ret = put_user(boot_status, (int __user *)arg);
> -		break;
> -
> -	case WDIOC_KEEPALIVE:
> -		wdt_keepalive();
> -		ret = 0;
> -		break;
> -
> -	case WDIOC_GETTIMEOUT:
> -		/* actually, it is 0.250 seconds.... */
> -		ret = put_user(1, (int __user *)arg);
> -		break;
> -	}
> -	return ret;
> -}
> -
> -static int ep93xx_wdt_release(struct inode *inode, struct file *file)
> -{
> -	if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
> -		wdt_shutdown();
> -	else
> -		printk(KERN_CRIT PFX
> -			"Device closed unexpectedly - timer will not stop\n");
> -
> -	clear_bit(WDT_IN_USE, &wdt_status);
> -	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
> -
> -	return 0;
> -}
> -
> -static const struct file_operations ep93xx_wdt_fops = {
> +static const struct watchdog_ops ep93xx_wdt_ops = {
>  	.owner		= THIS_MODULE,
> -	.write		= ep93xx_wdt_write,
> -	.unlocked_ioctl	= ep93xx_wdt_ioctl,
> -	.open		= ep93xx_wdt_open,
> -	.release	= ep93xx_wdt_release,
> -	.llseek		= no_llseek,
> +	.start		= ep93xx_wdt_start,
> +	.stop		= ep93xx_wdt_stop,
> +	.ping		= ep93xx_wdt_keepalive,
>  };
>  
> -static struct miscdevice ep93xx_wdt_miscdev = {
> -	.minor		= WATCHDOG_MINOR,
> -	.name		= "watchdog",
> -	.fops		= &ep93xx_wdt_fops,
> +static struct watchdog_device ep93xx_wdd = {
> +	.info		= &ep93xx_wdt_ident,
> +	.ops		= &ep93xx_wdt_ops,
> +	.min_timeout	= 1,
> +	.max_timeout	= 3600,
>  };
>  
>  static void ep93xx_timer_ping(unsigned long data)
>  {
>  	if (time_before(jiffies, next_heartbeat))
> -		wdt_ping();
> +		__raw_writew(EP93XX_WATCHDOG_RESTART, EP93XX_WDT_WATCHDOG);
>  
>  	/* Re-set the timer interval */
>  	mod_timer(&timer, jiffies + WDT_INTERVAL);
> @@ -208,45 +126,50 @@ static void ep93xx_timer_ping(unsigned long data)
>  
>  static int __init ep93xx_wdt_init(void)
>  {
> +	int v;
>  	int err;
>  
> -	err = misc_register(&ep93xx_wdt_miscdev);
> -
> -	boot_status = __raw_readl(EP93XX_WDT_WATCHDOG) & 0x01 ? 1 : 0;
> -
> -	printk(KERN_INFO PFX "EP93XX watchdog, driver version "
> -		WDT_VERSION "%s\n",
> -		(__raw_readl(EP93XX_WDT_WATCHDOG) & 0x08)
> -		? " (nCS1 disable detected)" : "");
> +	v = readl(EP93XX_WDT_WATCHDOG);
> +	ep93xx_wdd.bootstatus = (v & EP93XX_WATCHDOG_RESET_MASK)
> +				? WDIOF_CARDRESET : 0;
> +	if (ep93xx_wdd.bootstatus) {
> +		/* Only a power-on-reset will clear these bits */
> +		pr_info("Last reset was due to %s%s%s\n",
> +			(v & EP93XX_WATCHDOG_WD) ? "- watchdog timeout " : "",
> +			(v & EP93XX_WATCHDOG_3KRST) ? "- 3-key reset " : "",
> +			(v & EP93XX_WATCHDOG_URST) ? "- user reset" : "");
> +	}
>  
> -	if (timeout < 1 || timeout > 3600) {
> -		timeout = WDT_TIMEOUT;
> -		printk(KERN_INFO PFX
> -			"timeout value must be 1<=x<=3600, using %d\n",
> -			timeout);
> +	if (timeout < ep93xx_wdd.min_timeout ||
> +	    timeout > ep93xx_wdd.max_timeout) {
> +		ep93xx_wdd.timeout = WDT_TIMEOUT;
> +		pr_info("timeout value must be %d<=x<=%d, using %d\n",
> +			ep93xx_wdd.min_timeout, ep93xx_wdd.max_timeout,
> +			ep93xx_wdd.timeout);
> +	} else {
> +		ep93xx_wdd.timeout = timeout;
>  	}
>  
> +	err = watchdog_register_device(&ep93xx_wdd);
> +	if (err)
> +		return err;
> +
>  	setup_timer(&timer, ep93xx_timer_ping, 1);
> -	return err;
> +
> +	pr_info("EP93XX watchdog, driver version " WDT_VERSION "%s\n",
> +		(v & EP93XX_WATCHDOG_HWDIS) ? " (nCS1 disable detected)" : "");
> +
> +	return 0;
>  }
> +module_init(ep93xx_wdt_init);
>  
>  static void __exit ep93xx_wdt_exit(void)
>  {
> -	wdt_shutdown();
> -	misc_deregister(&ep93xx_wdt_miscdev);
> +	ep93xx_wdt_stop(&ep93xx_wdd);
> +	watchdog_unregister_device(&ep93xx_wdd);
>  }
> -
> -module_init(ep93xx_wdt_init);
>  module_exit(ep93xx_wdt_exit);
>  
> -module_param(nowayout, int, 0);
> -MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
> -
> -module_param(timeout, int, 0);
> -MODULE_PARM_DESC(timeout,
> -	"Watchdog timeout in seconds. (1<=timeout<=3600, default="
> -				__MODULE_STRING(WDT_TIMEOUT) ")");
> -
>  MODULE_AUTHOR("Ray Lehtiniemi <rayl@xxxxxxxx>,"
>  		"Alessandro Zummo <a.zummo@xxxxxxxxxxxx>");
>  MODULE_DESCRIPTION("EP93xx Watchdog");
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