RE: [PATCH] rtc: ds1374: wdt: Use watchdog core for watchdog part

[Johnson CH Chen (陳昭勳)]

Hi,

> > diff --git a/drivers/rtc/rtc-ds1374.c b/drivers/rtc/rtc-ds1374.c index
> > 9c51a12cf70f..25b28f7546ff 100644
> > --- a/drivers/rtc/rtc-ds1374.c
> > +++ b/drivers/rtc/rtc-ds1374.c
> > @@ -1,3 +1,4 @@
> > +// SPDX-License-Identifier: GPL-2.0
> >  /*
> >   * RTC client/driver for the Maxim/Dallas DS1374 Real-Time Clock over
> I2C
> >   *
> > @@ -6,11 +7,7 @@
> >   *
> >   * Copyright (C) 2014 Rose Technology
> >   * Copyright (C) 2006-2007 Freescale Semiconductor
> > - *
> > - * 2005 (c) MontaVista Software, Inc. This file is licensed under
> > - * the terms of the GNU General Public License version 2. This
> > program
> > - * is licensed "as is" without any warranty of any kind, whether
> > express
> > - * or implied.
> > + * Copyright (C) 2005 (c) MontaVista Software, Inc.
> >   */
> 
> The above should be a separate patch.
> 
> >  /*
> >   * It would be more efficient to use i2c msgs/i2c_transfer directly
> > but, as @@ -46,6 +43,7 @@
> >  #define DS1374_REG_WDALM2	0x06
> >  #define DS1374_REG_CR		0x07 /* Control */
> >  #define DS1374_REG_CR_AIE	0x01 /* Alarm Int. Enable */
> > +#define DS1374_REG_CR_WDSTR	0x08 /* 1=INT, 0=RST */
> >  #define DS1374_REG_CR_WDALM	0x20 /* 1=Watchdog, 0=Alarm */
> >  #define DS1374_REG_CR_WACE	0x40 /* WD/Alarm counter enable */
> >  #define DS1374_REG_SR		0x08 /* Status */
> > @@ -71,7 +69,9 @@ struct ds1374 {
> >  	struct i2c_client *client;
> >  	struct rtc_device *rtc;
> >  	struct work_struct work;
> > -
> > +#ifdef CONFIG_RTC_DRV_DS1374_WDT
> > +	struct watchdog_device wdt;
> > +#endif
> >  	/* The mutex protects alarm operations, and prevents a race
> >  	 * between the enable_irq() in the workqueue and the free_irq()
> >  	 * in the remove function.
> > @@ -257,7 +257,8 @@ static int ds1374_set_alarm(struct device *dev,
> struct rtc_wkalrm *alarm)
> >  		goto out;
> >
> >  	/* Disable any existing alarm before setting the new one
> > -	 * (or lack thereof). */
> > +	 * (or lack thereof).
> > +	 */
> 
> Unrelated (and cosmetic). Drop or separate patch.
> 
> >  	cr &= ~DS1374_REG_CR_WACE;
> >
> >  	ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr); @@
> > -371,14 +372,21 @@ static const struct rtc_class_ops ds1374_rtc_ops = {
> >   */
> >  static struct i2c_client *save_client;
> >  /* Default margin */
> > -#define WD_TIMO 131762
> > +#define TIMER_MARGIN_DEFAULT  32
> 
> Parameter alignment is off. Please use tab after TIMER_MARGIN_DEFAULT.
> 
> > +#define TIMER_MARGIN_MIN	1
> > +#define TIMER_MARGIN_MAX	(60*60*24) /* one day */
> 
> Real limits are necessary. The old limit was 16777216/4096 = 4096 seconds.
> 
> Ok, time to look up the datasheet. The counter is a 24-bit value.
> The maximum value is thus 0xffffff, or 16777215. 16777215 / 4096 = 4095,
> which should be the maximum timeout in seconds to set here.
> 
> >
> >  #define DRV_NAME "DS1374 Watchdog"
> >
> > -static int wdt_margin = WD_TIMO;
> > -static unsigned long wdt_is_open;
> > -module_param(wdt_margin, int, 0);
> > -MODULE_PARM_DESC(wdt_margin, "Watchdog timeout in seconds (default
> > 32s)");
> > +static int timeout = TIMER_MARGIN_DEFAULT; module_param(timeout, int,
> > +0); MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default
> > +32s)");
> 
> This changes the module parameter which may be unexpected.
> I would suggest to keep using wdt_margin.
> 
> > +
> > +static bool nowayout = WATCHDOG_NOWAYOUT; module_param(nowayout,
> > +bool, 0); MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped
> once
> > +started (default ="
> > +		__MODULE_STRING(WATCHDOG_NOWAYOUT)")");
> > +
> >
> >  static const struct watchdog_info ds1374_wdt_info = {
> >  	.identity       = "DS1374 WTD",
> > @@ -386,57 +394,61 @@ static const struct watchdog_info
> ds1374_wdt_info = {
> >  						WDIOF_MAGICCLOSE,
> >  };
> >
> > -static int ds1374_wdt_settimeout(unsigned int timeout)
> > +static int ds1374_wdt_settimeout(struct watchdog_device *wdt,
> > +					unsigned int timeout)
> 
> This fits into one line (new line length limit)
> 
> >  {
> > -	int ret = -ENOIOCTLCMD;
> > -	int cr;
> > +	int ret, cr;
> > +
> > +	wdt->timeout = timeout;
> >
> > -	ret = cr = i2c_smbus_read_byte_data(save_client, DS1374_REG_CR);
> > +	cr = i2c_smbus_read_byte_data(save_client, DS1374_REG_CR);
> > +	ret = cr;
> >  	if (ret < 0)
> > -		goto out;
> > +		return ret;
> >
> Assignment to ret is pointless. Just return cr if negative.
> 
> >  	/* Disable any existing watchdog/alarm before setting the new one */
> >  	cr &= ~DS1374_REG_CR_WACE;
> >
> >  	ret = i2c_smbus_write_byte_data(save_client, DS1374_REG_CR, cr);
> >  	if (ret < 0)
> > -		goto out;
> > +		return ret;
> >
> >  	/* Set new watchdog time */
> > +	timeout = timeout * 4096;
> >  	ret = ds1374_write_rtc(save_client, timeout, DS1374_REG_WDALM0, 3);
> >  	if (ret) {
> >  		pr_info("couldn't set new watchdog time\n");
> > -		goto out;
> > +		return ret;
> >  	}
> >
> >  	/* Enable watchdog timer */
> >  	cr |= DS1374_REG_CR_WACE | DS1374_REG_CR_WDALM;
> > +	cr &= ~DS1374_REG_CR_WDSTR;/* for RST PIN */
> >  	cr &= ~DS1374_REG_CR_AIE;
> >
> >  	ret = i2c_smbus_write_byte_data(save_client, DS1374_REG_CR, cr);
> >  	if (ret < 0)
> > -		goto out;
> > +		return ret;
> >
> >  	return 0;
> > -out:
> > -	return ret;
> >  }
> >
> > -
> >  /*
> >   * Reload the watchdog timer.  (ie, pat the watchdog)
> >   */
> > -static void ds1374_wdt_ping(void)
> > +static int ds1374_wdt_ping(struct watchdog_device *wdt)
> >  {
> >  	u32 val;
> > -	int ret = 0;
> >
> > -	ret = ds1374_read_rtc(save_client, &val, DS1374_REG_WDALM0, 3);
> > -	if (ret)
> > -		pr_info("WD TICK FAIL!!!!!!!!!! %i\n", ret);
> > +	return ds1374_read_rtc(save_client, &val, DS1374_REG_WDALM0, 3); }
> > +
> > +static int ds1374_wdt_start(struct watchdog_device *wdt) {
> > +	return ds1374_wdt_ping(wdt);
> 
> Unnecessary. Just declare the start function and drop the ping function.
> See Documentation/watchdog/watchdog-kernel-api.rst
> 
> >  }
> >
> > -static void ds1374_wdt_disable(void)
> > +static int ds1374_wdt_stop(struct watchdog_device *wdt)
> >  {
> >  	int cr;
> >
> > @@ -444,162 +456,17 @@ static void ds1374_wdt_disable(void)
> >  	/* Disable watchdog timer */
> >  	cr &= ~DS1374_REG_CR_WACE;
> >
> > -	i2c_smbus_write_byte_data(save_client, DS1374_REG_CR, cr);
> > +	return i2c_smbus_write_byte_data(save_client, DS1374_REG_CR, cr);
> >  }
> >
> > -/*
> > - * Watchdog device is opened, and watchdog starts running.
> > - */
> > -static int ds1374_wdt_open(struct inode *inode, struct file *file) -{
> > -	struct ds1374 *ds1374 = i2c_get_clientdata(save_client);
> > -
> > -	if (MINOR(inode->i_rdev) == WATCHDOG_MINOR) {
> > -		mutex_lock(&ds1374->mutex);
> > -		if (test_and_set_bit(0, &wdt_is_open)) {
> > -			mutex_unlock(&ds1374->mutex);
> > -			return -EBUSY;
> > -		}
> > -		/*
> > -		 *      Activate
> > -		 */
> > -		wdt_is_open = 1;
> > -		mutex_unlock(&ds1374->mutex);
> > -		return stream_open(inode, file);
> > -	}
> > -	return -ENODEV;
> > -}
> > -
> > -/*
> > - * Close the watchdog device.
> > - */
> > -static int ds1374_wdt_release(struct inode *inode, struct file *file)
> > -{
> > -	if (MINOR(inode->i_rdev) == WATCHDOG_MINOR)
> > -		clear_bit(0, &wdt_is_open);
> > -
> > -	return 0;
> > -}
> > -
> > -/*
> > - * Pat the watchdog whenever device is written to.
> > - */
> > -static ssize_t ds1374_wdt_write(struct file *file, const char __user *data,
> > -				size_t len, loff_t *ppos)
> > -{
> > -	if (len) {
> > -		ds1374_wdt_ping();
> > -		return 1;
> > -	}
> > -	return 0;
> > -}
> > -
> > -static ssize_t ds1374_wdt_read(struct file *file, char __user *data,
> > -				size_t len, loff_t *ppos)
> > -{
> > -	return 0;
> > -}
> > -
> > -/*
> > - * Handle commands from user-space.
> > - */
> > -static long ds1374_wdt_ioctl(struct file *file, unsigned int cmd,
> > -							unsigned long arg)
> > -{
> > -	int new_margin, options;
> > -
> > -	switch (cmd) {
> > -	case WDIOC_GETSUPPORT:
> > -		return copy_to_user((struct watchdog_info __user *)arg,
> > -		&ds1374_wdt_info, sizeof(ds1374_wdt_info)) ? -EFAULT : 0;
> > -
> > -	case WDIOC_GETSTATUS:
> > -	case WDIOC_GETBOOTSTATUS:
> > -		return put_user(0, (int __user *)arg);
> > -	case WDIOC_KEEPALIVE:
> > -		ds1374_wdt_ping();
> > -		return 0;
> > -	case WDIOC_SETTIMEOUT:
> > -		if (get_user(new_margin, (int __user *)arg))
> > -			return -EFAULT;
> > -
> > -		/* the hardware's tick rate is 4096 Hz, so
> > -		 * the counter value needs to be scaled accordingly
> > -		 */
> > -		new_margin <<= 12;
> > -		if (new_margin < 1 || new_margin > 16777216)
> > -			return -EINVAL;
> > -
> > -		wdt_margin = new_margin;
> > -		ds1374_wdt_settimeout(new_margin);
> > -		ds1374_wdt_ping();
> > -		/* fallthrough */
> > -	case WDIOC_GETTIMEOUT:
> > -		/* when returning ... inverse is true */
> > -		return put_user((wdt_margin >> 12), (int __user *)arg);
> > -	case WDIOC_SETOPTIONS:
> > -		if (copy_from_user(&options, (int __user *)arg, sizeof(int)))
> > -			return -EFAULT;
> > -
> > -		if (options & WDIOS_DISABLECARD) {
> > -			pr_info("disable watchdog\n");
> > -			ds1374_wdt_disable();
> > -			return 0;
> > -		}
> > -
> > -		if (options & WDIOS_ENABLECARD) {
> > -			pr_info("enable watchdog\n");
> > -			ds1374_wdt_settimeout(wdt_margin);
> > -			ds1374_wdt_ping();
> > -			return 0;
> > -		}
> > -		return -EINVAL;
> > -	}
> > -	return -ENOTTY;
> > -}
> > -
> > -static long ds1374_wdt_unlocked_ioctl(struct file *file, unsigned int cmd,
> > -			unsigned long arg)
> > -{
> > -	int ret;
> > -	struct ds1374 *ds1374 = i2c_get_clientdata(save_client);
> > -
> > -	mutex_lock(&ds1374->mutex);
> > -	ret = ds1374_wdt_ioctl(file, cmd, arg);
> > -	mutex_unlock(&ds1374->mutex);
> > -
> > -	return ret;
> > -}
> > -
> > -static int ds1374_wdt_notify_sys(struct notifier_block *this,
> > -			unsigned long code, void *unused)
> > -{
> > -	if (code == SYS_DOWN || code == SYS_HALT)
> > -		/* Disable Watchdog */
> > -		ds1374_wdt_disable();
> > -	return NOTIFY_DONE;
> > -}
> > -
> > -static const struct file_operations ds1374_wdt_fops = {
> > -	.owner			= THIS_MODULE,
> > -	.read			= ds1374_wdt_read,
> > -	.unlocked_ioctl		= ds1374_wdt_unlocked_ioctl,
> > -	.compat_ioctl		= compat_ptr_ioctl,
> > -	.write			= ds1374_wdt_write,
> > -	.open                   = ds1374_wdt_open,
> > -	.release                = ds1374_wdt_release,
> > -	.llseek			= no_llseek,
> > -};
> > -
> > -static struct miscdevice ds1374_miscdev = {
> > -	.minor          = WATCHDOG_MINOR,
> > -	.name           = "watchdog",
> > -	.fops           = &ds1374_wdt_fops,
> > +static const struct watchdog_ops ds1374_wdt_fops = {
> 
> s/fops/ops/
> 
> Those are not file operations.
> 
> > +	.owner          = THIS_MODULE,
> > +	.start          = ds1374_wdt_start,
> > +	.stop           = ds1374_wdt_stop,
> > +	.ping           = ds1374_wdt_ping,
> > +	.set_timeout    = ds1374_wdt_settimeout,
> >  };
> >
> > -static struct notifier_block ds1374_wdt_notifier = {
> > -	.notifier_call = ds1374_wdt_notify_sys,
> > -};
> >
> >  #endif /*CONFIG_RTC_DRV_DS1374_WDT*/
> >  /*
> > @@ -653,15 +520,25 @@ static int ds1374_probe(struct i2c_client *client,
> >
> >  #ifdef CONFIG_RTC_DRV_DS1374_WDT
> >  	save_client = client;
> > -	ret = misc_register(&ds1374_miscdev);
> > -	if (ret)
> > -		return ret;
> > -	ret = register_reboot_notifier(&ds1374_wdt_notifier);
> > +	ds1374->wdt.info = &ds1374_wdt_info;
> > +	ds1374->wdt.ops = &ds1374_wdt_fops;
> > +	ds1374->wdt.timeout = TIMER_MARGIN_DEFAULT;
> > +	ds1374->wdt.min_timeout = TIMER_MARGIN_MIN;
> > +	ds1374->wdt.max_timeout = TIMER_MARGIN_MAX;
> > +
> > +	watchdog_init_timeout(&ds1374->wdt, timeout, &client->dev);
> > +	watchdog_set_nowayout(&ds1374->wdt, nowayout);
> > +	watchdog_stop_on_reboot(&ds1374->wdt);
> > +	watchdog_stop_on_unregister(&ds1374->wdt);
> > +
> > +	ret = devm_watchdog_register_device(&client->dev, &ds1374->wdt);
> >  	if (ret) {
> > -		misc_deregister(&ds1374_miscdev);
> > +		dev_err(&client->dev, "failed to register DS1374 watchdog
> device\n");
> >  		return ret;
> >  	}
> > -	ds1374_wdt_settimeout(131072);
> > +
> > +	ds1374_wdt_settimeout(&ds1374->wdt, timeout);
> 
> You'll want to do that before registering the watchdog to avoid a
> race condition.
> 
> > +	dev_info(&client->dev, "DS1374 watchdog device enabled\n");
> >  #endif
> >
> >  	return 0;
> > @@ -670,10 +547,10 @@ static int ds1374_probe(struct i2c_client *client,
> >  static int ds1374_remove(struct i2c_client *client)
> >  {
> >  	struct ds1374 *ds1374 = i2c_get_clientdata(client);
> > +
> >  #ifdef CONFIG_RTC_DRV_DS1374_WDT
> > -	misc_deregister(&ds1374_miscdev);
> > -	ds1374_miscdev.parent = NULL;
> > -	unregister_reboot_notifier(&ds1374_wdt_notifier);
> > +	dev_warn(&client->dev, "Unregister DS1374 watchdog device\n");
> 
> Noise.
> 
> > +	watchdog_unregister_device(&ds1374->wdt);
> 
> Drop: The watchdog was registered using devm_watchdog_register_device().
> 

Thanks for your good suggestions. I'll fix them and kernel test robot by v2.

> >  #endif
> >
> >  	if (client->irq > 0) {
> >

Best regards,
Johnson