cpwatchdog.c

该文件是rt_linux

		return -ESPIPE;

	if (count) {
		wd_pingtimer(pTimer);
		return 1;
	}
	return 0;
}

static ssize_t wd_read(struct file * file, char * buffer,
		        size_t count, loff_t *ppos)
{
#ifdef WD_DEBUG
	wd_dumpregs();
	return(0);
#else
	return(-EINVAL);
#endif /* ifdef WD_DEBUG */
}

static void wd_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
	/* Only WD0 will interrupt-- others are NMI and we won't
	 * see them here....
	 */
	spin_lock_irq(&wd_dev.lock);
	if((unsigned long)wd_dev.regs == (unsigned long)dev_id)
	{
		wd_stoptimer(&wd_dev.watchdog[WD0_ID]);
		wd_dev.watchdog[WD0_ID].runstatus |=  WD_STAT_SVCD;
	}
	spin_unlock_irq(&wd_dev.lock);
	return;
}

static struct file_operations wd_fops = {
	owner:		THIS_MODULE,
	ioctl:		wd_ioctl,
	open:		wd_open,
	write:		wd_write,
	read:		wd_read,
	release:	wd_release,
};

static struct miscdevice wd0_miscdev = { WD0_MINOR, WD0_DEVNAME, &wd_fops };
static struct miscdevice wd1_miscdev = { WD1_MINOR, WD1_DEVNAME, &wd_fops };
static struct miscdevice wd2_miscdev = { WD2_MINOR, WD2_DEVNAME, &wd_fops };

#ifdef WD_DEBUG
static void wd_dumpregs(void)
{
	/* Reading from downcounters initiates watchdog countdown--
	 * Example is included below for illustration purposes.
	 */
	int i;
	printk("%s: dumping register values\n", WD_OBPNAME);
	for(i = WD0_ID; i < WD_NUMDEVS; ++i) {
			/* printk("\t%s%i: dcntr  at 0x%lx: 0x%x\n", 
			 * 	WD_OBPNAME,
		 	 *	i,
			 *	(unsigned long)(&wd_dev.watchdog[i].regs->dcntr), 
			 *	readw(&wd_dev.watchdog[i].regs->dcntr));
			 */
			printk("\t%s%i: limit  at 0x%lx: 0x%x\n", 
				WD_OBPNAME,
				i,
				(unsigned long)(&wd_dev.watchdog[i].regs->limit), 
				readw(&wd_dev.watchdog[i].regs->limit));
			printk("\t%s%i: status at 0x%lx: 0x%x\n", 
				WD_OBPNAME,
				i,
				(unsigned long)(&wd_dev.watchdog[i].regs->status), 
				readb(&wd_dev.watchdog[i].regs->status));
			printk("\t%s%i: driver status: 0x%x\n",
				WD_OBPNAME,
				i,
				wd_getstatus(&wd_dev.watchdog[i]));
	}
	printk("\tintr_mask  at 0x%lx: 0x%x\n", 
		(unsigned long)(&wd_dev.regs->pld_regs.intr_mask), 
		readb(&wd_dev.regs->pld_regs.intr_mask));
	printk("\tpld_status at 0x%lx: 0x%x\n", 
		(unsigned long)(&wd_dev.regs->pld_regs.status), 
		readb(&wd_dev.regs->pld_regs.status));
}
#endif

/* Enable or disable watchdog interrupts
 * Because of the CP1400 defect this should only be
 * called during initialzation or by wd_[start|stop]timer()
 *
 * pTimer 	- pointer to timer device, or NULL to indicate all timers 
 * enable	- non-zero to enable interrupts, zero to disable
 */
static void wd_toggleintr(struct wd_timer* pTimer, int enable)
{
	unsigned char curregs = wd_readb(&wd_dev.regs->pld_regs.intr_mask);
	unsigned char setregs = 
		(NULL == pTimer) ? 
			(WD0_INTR_MASK | WD1_INTR_MASK | WD2_INTR_MASK) : 
			(pTimer->intr_mask);

	(WD_INTR_ON == enable) ?
		(curregs &= ~setregs):
		(curregs |=  setregs);

	wd_writeb(curregs, &wd_dev.regs->pld_regs.intr_mask);
	return;
}

/* Reset countdown timer with 'limit' value and continue countdown.
 * This will not start a stopped timer.
 *
 * pTimer	- pointer to timer device
 */
static void wd_pingtimer(struct wd_timer* pTimer)
{
	if(wd_readb(&pTimer->regs->status) & WD_S_RUNNING) {
		wd_readb(&pTimer->regs->dcntr);
	}
}

/* Stop a running watchdog timer-- the timer actually keeps
 * running, but the interrupt is masked so that no action is
 * taken upon expiration.
 *
 * pTimer	- pointer to timer device
 */
static void wd_stoptimer(struct wd_timer* pTimer)
{
	if(wd_readb(&pTimer->regs->status) & WD_S_RUNNING) {
		wd_toggleintr(pTimer, WD_INTR_OFF);

		if(wd_dev.isbaddoggie) {
			pTimer->runstatus |= WD_STAT_BSTOP;
			wd_brokentimer((unsigned long)&wd_dev);
		}
	}
}

/* Start a watchdog timer with the specified limit value
 * If the watchdog is running, it will be restarted with
 * the provided limit value.
 *
 * This function will enable interrupts on the specified
 * watchdog.
 *
 * pTimer	- pointer to timer device
 * limit	- limit (countdown) value in 1/10th seconds
 */
static void wd_starttimer(struct wd_timer* pTimer)
{
	if(wd_dev.isbaddoggie) {
		pTimer->runstatus &= ~WD_STAT_BSTOP;
	}
	pTimer->runstatus &= ~WD_STAT_SVCD;

	wd_writew(pTimer->timeout, &pTimer->regs->limit);
	wd_toggleintr(pTimer, WD_INTR_ON);
}

/* Restarts timer with maximum limit value and
 * does not unset 'brokenstop' value.
 */
static void wd_resetbrokentimer(struct wd_timer* pTimer)
{
	wd_toggleintr(pTimer, WD_INTR_ON);
	wd_writew(WD_BLIMIT, &pTimer->regs->limit);
}

/* Timer device initialization helper.
 * Returns 0 on success, other on failure
 */
static int wd_inittimer(int whichdog)
{
	struct miscdevice 				*whichmisc;
	volatile struct wd_timer_regblk	*whichregs;
	char 							whichident[8];
	int								whichmask;
	__u16							whichlimit;

	switch(whichdog)
	{
		case WD0_ID:
			whichmisc = &wd0_miscdev;
			strcpy(whichident, "RIC");
			whichregs = &wd_dev.regs->wd0_regs;
			whichmask = WD0_INTR_MASK;
			whichlimit= (0 == wd0_timeout) 	? 
						(wd_dev.opt_timeout): 
						(wd0_timeout);
			break;
		case WD1_ID:
			whichmisc = &wd1_miscdev;
			strcpy(whichident, "XIR");
			whichregs = &wd_dev.regs->wd1_regs;
			whichmask = WD1_INTR_MASK;
			whichlimit= (0 == wd1_timeout) 	? 
						(wd_dev.opt_timeout): 
						(wd1_timeout);
			break;
		case WD2_ID:
			whichmisc = &wd2_miscdev;
			strcpy(whichident, "POR");
			whichregs = &wd_dev.regs->wd2_regs;
			whichmask = WD2_INTR_MASK;
			whichlimit= (0 == wd2_timeout) 	? 
						(wd_dev.opt_timeout): 
						(wd2_timeout);
			break;
		default:
			printk("%s: %s: invalid watchdog id: %i\n",
				WD_OBPNAME, __FUNCTION__, whichdog);
			return(1);
	}
	if(0 != misc_register(whichmisc))
	{
		return(1);
	}
	wd_dev.watchdog[whichdog].regs			= whichregs;
	wd_dev.watchdog[whichdog].timeout 		= whichlimit;
	wd_dev.watchdog[whichdog].intr_mask		= whichmask;
	wd_dev.watchdog[whichdog].runstatus 	&= ~WD_STAT_BSTOP;
	wd_dev.watchdog[whichdog].runstatus 	|= WD_STAT_INIT;

	printk("%s%i: %s hardware watchdog [%01i.%i sec] %s\n", 
		WD_OBPNAME, 
		whichdog, 
		whichident, 
		wd_dev.watchdog[whichdog].timeout / 10,
		wd_dev.watchdog[whichdog].timeout % 10,
		(0 != wd_dev.opt_enable) ? "in ENABLED mode" : "");
	return(0);
}

/* Timer method called to reset stopped watchdogs--
 * because of the PLD bug on CP1400, we cannot mask
 * interrupts within the PLD so me must continually
 * reset the timers ad infinitum.
 */
static void wd_brokentimer(unsigned long data)
{
	struct wd_device* pDev = (struct wd_device*)data;
	int id, tripped = 0;

	/* kill a running timer instance, in case we
	 * were called directly instead of by kernel timer
	 */
	if(timer_pending(&wd_timer)) {
		del_timer(&wd_timer);
	}

	for(id = WD0_ID; id < WD_NUMDEVS; ++id) {
		if(pDev->watchdog[id].runstatus & WD_STAT_BSTOP) {
			++tripped;
			wd_resetbrokentimer(&pDev->watchdog[id]);
		}
	}

	if(tripped) {
		/* there is at least one timer brokenstopped-- reschedule */
		wd_timer.expires = WD_BTIMEOUT;
		add_timer(&wd_timer);
	}
}

static int wd_getstatus(struct wd_timer* pTimer)
{
	unsigned char stat = wd_readb(&pTimer->regs->status);
	unsigned char intr = wd_readb(&wd_dev.regs->pld_regs.intr_mask);
	unsigned char ret  = WD_STOPPED;

	/* determine STOPPED */
	if(0 == stat ) { 
		return(ret);
	}
	/* determine EXPIRED vs FREERUN vs RUNNING */
	else if(WD_S_EXPIRED & stat) {
		ret = WD_EXPIRED;
	}
	else if(WD_S_RUNNING & stat) {
		if(intr & pTimer->intr_mask) {
			ret = WD_FREERUN;
		}
		else {
			/* Fudge WD_EXPIRED status for defective CP1400--
			 * IF timer is running 
			 * 	AND brokenstop is set 
			 * 	AND an interrupt has been serviced
			 * we are WD_EXPIRED.
			 *
			 * IF timer is running 
			 * 	AND brokenstop is set 
			 * 	AND no interrupt has been serviced
			 * we are WD_FREERUN.
			 */
			if(wd_dev.isbaddoggie && (pTimer->runstatus & WD_STAT_BSTOP)) {
				if(pTimer->runstatus & WD_STAT_SVCD) {
					ret = WD_EXPIRED;
				}
				else {
					/* we could as well pretend we are expired */
					ret = WD_FREERUN;
				}
			}
			else {
				ret = WD_RUNNING;
			}
		}
	}

	/* determine SERVICED */
	if(pTimer->runstatus & WD_STAT_SVCD) {
		ret |= WD_SERVICED;
	}

	return(ret);
}

static int __init wd_init(void)
{
	int 	id;
	struct 	linux_ebus *ebus = NULL;
	struct 	linux_ebus_device *edev = NULL;

	for_each_ebus(ebus) {
		for_each_ebusdev(edev, ebus) {
			if (!strcmp(edev->prom_name, WD_OBPNAME))
				goto ebus_done;
		}
	}

ebus_done:
	if(!edev) {
		printk("%s: unable to locate device\n", WD_OBPNAME);
		return -ENODEV;
	}

	wd_dev.regs = 
		ioremap(edev->resource[0].start, sizeof(struct wd_regblk));

	if(NULL == wd_dev.regs) {
		printk("%s: unable to map registers\n", WD_OBPNAME);
		return(-ENODEV);
	}

	/* initialize device structure from OBP parameters */
	wd_dev.irq 			= edev->irqs[0];
	wd_dev.opt_enable	= wd_opt_enable();
	wd_dev.opt_reboot	= wd_opt_reboot();
	wd_dev.opt_timeout	= wd_opt_timeout();
	wd_dev.isbaddoggie	= wd_isbroken();

	/* disable all interrupts unless watchdog-enabled? == true */
	if(! wd_dev.opt_enable) {
		wd_toggleintr(NULL, WD_INTR_OFF);
	}

	/* register miscellaneous devices */
	for(id = WD0_ID; id < WD_NUMDEVS; ++id) {
		if(0 != wd_inittimer(id)) {
			printk("%s%i: unable to initialize\n", WD_OBPNAME, id);
		}
	}

	/* warn about possible defective PLD */
	if(wd_dev.isbaddoggie) {
		init_timer(&wd_timer);
		wd_timer.function 	= wd_brokentimer;
		wd_timer.data		= (unsigned long)&wd_dev;
		wd_timer.expires	= WD_BTIMEOUT;

		printk("%s: PLD defect workaround enabled for model %s\n",
			WD_OBPNAME, WD_BADMODEL);
	}
	return(0);
}

static void __exit wd_cleanup(void)
{
	int id;

	/* if 'watchdog-enable?' == TRUE, timers are not stopped 
	 * when module is unloaded.  All brokenstopped timers will
	 * also now eventually trip. 
	 */
	for(id = WD0_ID; id < WD_NUMDEVS; ++id) {
		if(WD_S_RUNNING == wd_readb(&wd_dev.watchdog[id].regs->status)) {
			if(wd_dev.opt_enable) {
				printk(KERN_WARNING "%s%i: timer not stopped at release\n",
					WD_OBPNAME, id);
			}
			else {
				wd_stoptimer(&wd_dev.watchdog[id]);
				if(wd_dev.watchdog[id].runstatus & WD_STAT_BSTOP) {
					wd_resetbrokentimer(&wd_dev.watchdog[id]);
					printk(KERN_WARNING 
							"%s%i: defect workaround disabled at release, "\
							"timer expires in ~%01i sec\n",
							WD_OBPNAME, id, 
							wd_readw(&wd_dev.watchdog[id].regs->limit) / 10);
				}
			}
		}
	}

	if(wd_dev.isbaddoggie && timer_pending(&wd_timer)) {
		del_timer(&wd_timer);
	}
	if(0 != (wd_dev.watchdog[WD0_ID].runstatus & WD_STAT_INIT)) {
		misc_deregister(&wd0_miscdev);
	}
	if(0 != (wd_dev.watchdog[WD1_ID].runstatus & WD_STAT_INIT)) {
		misc_deregister(&wd1_miscdev);
	}
	if(0 != (wd_dev.watchdog[WD2_ID].runstatus & WD_STAT_INIT)) {
		misc_deregister(&wd2_miscdev);
	}
	if(0 != wd_dev.initialized) {
		free_irq(wd_dev.irq, (void *)wd_dev.regs);
	}
	iounmap(wd_dev.regs);
}

module_init(wd_init);
module_exit(wd_cleanup);