xref: /openbmc/linux/drivers/watchdog/cpwd.c (revision cc85f87a)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /* cpwd.c - driver implementation for hardware watchdog
3  * timers found on Sun Microsystems CP1400 and CP1500 boards.
4  *
5  * This device supports both the generic Linux watchdog
6  * interface and Solaris-compatible ioctls as best it is
7  * able.
8  *
9  * NOTE:	CP1400 systems appear to have a defective intr_mask
10  *			register on the PLD, preventing the disabling of
11  *			timer interrupts.  We use a timer to periodically
12  *			reset 'stopped' watchdogs on affected platforms.
13  *
14  * Copyright (c) 2000 Eric Brower (ebrower@usa.net)
15  * Copyright (C) 2008 David S. Miller <davem@davemloft.net>
16  */
17 
18 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
19 
20 #include <linux/kernel.h>
21 #include <linux/module.h>
22 #include <linux/fs.h>
23 #include <linux/errno.h>
24 #include <linux/major.h>
25 #include <linux/miscdevice.h>
26 #include <linux/interrupt.h>
27 #include <linux/ioport.h>
28 #include <linux/timer.h>
29 #include <linux/compat.h>
30 #include <linux/slab.h>
31 #include <linux/mutex.h>
32 #include <linux/io.h>
33 #include <linux/of.h>
34 #include <linux/platform_device.h>
35 #include <linux/uaccess.h>
36 
37 #include <asm/irq.h>
38 #include <asm/watchdog.h>
39 
40 #define DRIVER_NAME	"cpwd"
41 
42 #define WD_OBPNAME	"watchdog"
43 #define WD_BADMODEL	"SUNW,501-5336"
44 #define WD_BTIMEOUT	(jiffies + (HZ * 1000))
45 #define WD_BLIMIT	0xFFFF
46 
47 #define WD0_MINOR	212
48 #define WD1_MINOR	213
49 #define WD2_MINOR	214
50 
51 /* Internal driver definitions.  */
52 #define WD0_ID			0
53 #define WD1_ID			1
54 #define WD2_ID			2
55 #define WD_NUMDEVS		3
56 
57 #define WD_INTR_OFF		0
58 #define WD_INTR_ON		1
59 
60 #define WD_STAT_INIT	0x01	/* Watchdog timer is initialized	*/
61 #define WD_STAT_BSTOP	0x02	/* Watchdog timer is brokenstopped	*/
62 #define WD_STAT_SVCD	0x04	/* Watchdog interrupt occurred		*/
63 
64 /* Register value definitions
65  */
66 #define WD0_INTR_MASK	0x01	/* Watchdog device interrupt masks	*/
67 #define WD1_INTR_MASK	0x02
68 #define WD2_INTR_MASK	0x04
69 
70 #define WD_S_RUNNING	0x01	/* Watchdog device status running	*/
71 #define WD_S_EXPIRED	0x02	/* Watchdog device status expired	*/
72 
73 struct cpwd {
74 	void __iomem	*regs;
75 	spinlock_t	lock;
76 
77 	unsigned int	irq;
78 
79 	unsigned long	timeout;
80 	bool		enabled;
81 	bool		reboot;
82 	bool		broken;
83 	bool		initialized;
84 
85 	struct {
86 		struct miscdevice	misc;
87 		void __iomem		*regs;
88 		u8			intr_mask;
89 		u8			runstatus;
90 		u16			timeout;
91 	} devs[WD_NUMDEVS];
92 };
93 
94 static DEFINE_MUTEX(cpwd_mutex);
95 static struct cpwd *cpwd_device;
96 
97 /* Sun uses Altera PLD EPF8820ATC144-4
98  * providing three hardware watchdogs:
99  *
100  * 1) RIC - sends an interrupt when triggered
101  * 2) XIR - asserts XIR_B_RESET when triggered, resets CPU
102  * 3) POR - asserts POR_B_RESET when triggered, resets CPU, backplane, board
103  *
104  *** Timer register block definition (struct wd_timer_regblk)
105  *
106  * dcntr and limit registers (halfword access):
107  * -------------------
108  * | 15 | ...| 1 | 0 |
109  * -------------------
110  * |-  counter val  -|
111  * -------------------
112  * dcntr -	Current 16-bit downcounter value.
113  *			When downcounter reaches '0' watchdog expires.
114  *			Reading this register resets downcounter with
115  *			'limit' value.
116  * limit -	16-bit countdown value in 1/10th second increments.
117  *			Writing this register begins countdown with input value.
118  *			Reading from this register does not affect counter.
119  * NOTES:	After watchdog reset, dcntr and limit contain '1'
120  *
121  * status register (byte access):
122  * ---------------------------
123  * | 7 | ... | 2 |  1  |  0  |
124  * --------------+------------
125  * |-   UNUSED  -| EXP | RUN |
126  * ---------------------------
127  * status-	Bit 0 - Watchdog is running
128  *			Bit 1 - Watchdog has expired
129  *
130  *** PLD register block definition (struct wd_pld_regblk)
131  *
132  * intr_mask register (byte access):
133  * ---------------------------------
134  * | 7 | ... | 3 |  2  |  1  |  0  |
135  * +-------------+------------------
136  * |-   UNUSED  -| WD3 | WD2 | WD1 |
137  * ---------------------------------
138  * WD3 -  1 == Interrupt disabled for watchdog 3
139  * WD2 -  1 == Interrupt disabled for watchdog 2
140  * WD1 -  1 == Interrupt disabled for watchdog 1
141  *
142  * pld_status register (byte access):
143  * UNKNOWN, MAGICAL MYSTERY REGISTER
144  *
145  */
146 #define WD_TIMER_REGSZ	16
147 #define WD0_OFF		0
148 #define WD1_OFF		(WD_TIMER_REGSZ * 1)
149 #define WD2_OFF		(WD_TIMER_REGSZ * 2)
150 #define PLD_OFF		(WD_TIMER_REGSZ * 3)
151 
152 #define WD_DCNTR	0x00
153 #define WD_LIMIT	0x04
154 #define WD_STATUS	0x08
155 
156 #define PLD_IMASK	(PLD_OFF + 0x00)
157 #define PLD_STATUS	(PLD_OFF + 0x04)
158 
159 static struct timer_list cpwd_timer;
160 
161 static int wd0_timeout;
162 static int wd1_timeout;
163 static int wd2_timeout;
164 
165 module_param(wd0_timeout, int, 0);
166 MODULE_PARM_DESC(wd0_timeout, "Default watchdog0 timeout in 1/10secs");
167 module_param(wd1_timeout, int, 0);
168 MODULE_PARM_DESC(wd1_timeout, "Default watchdog1 timeout in 1/10secs");
169 module_param(wd2_timeout, int, 0);
170 MODULE_PARM_DESC(wd2_timeout, "Default watchdog2 timeout in 1/10secs");
171 
172 MODULE_AUTHOR("Eric Brower <ebrower@usa.net>");
173 MODULE_DESCRIPTION("Hardware watchdog driver for Sun Microsystems CP1400/1500");
174 MODULE_LICENSE("GPL");
175 
cpwd_writew(u16 val,void __iomem * addr)176 static void cpwd_writew(u16 val, void __iomem *addr)
177 {
178 	writew(cpu_to_le16(val), addr);
179 }
cpwd_readw(void __iomem * addr)180 static u16 cpwd_readw(void __iomem *addr)
181 {
182 	u16 val = readw(addr);
183 
184 	return le16_to_cpu(val);
185 }
186 
cpwd_writeb(u8 val,void __iomem * addr)187 static void cpwd_writeb(u8 val, void __iomem *addr)
188 {
189 	writeb(val, addr);
190 }
191 
cpwd_readb(void __iomem * addr)192 static u8 cpwd_readb(void __iomem *addr)
193 {
194 	return readb(addr);
195 }
196 
197 /* Enable or disable watchdog interrupts
198  * Because of the CP1400 defect this should only be
199  * called during initialzation or by wd_[start|stop]timer()
200  *
201  * index	- sub-device index, or -1 for 'all'
202  * enable	- non-zero to enable interrupts, zero to disable
203  */
cpwd_toggleintr(struct cpwd * p,int index,int enable)204 static void cpwd_toggleintr(struct cpwd *p, int index, int enable)
205 {
206 	unsigned char curregs = cpwd_readb(p->regs + PLD_IMASK);
207 	unsigned char setregs =
208 		(index == -1) ?
209 		(WD0_INTR_MASK | WD1_INTR_MASK | WD2_INTR_MASK) :
210 		(p->devs[index].intr_mask);
211 
212 	if (enable == WD_INTR_ON)
213 		curregs &= ~setregs;
214 	else
215 		curregs |= setregs;
216 
217 	cpwd_writeb(curregs, p->regs + PLD_IMASK);
218 }
219 
220 /* Restarts timer with maximum limit value and
221  * does not unset 'brokenstop' value.
222  */
cpwd_resetbrokentimer(struct cpwd * p,int index)223 static void cpwd_resetbrokentimer(struct cpwd *p, int index)
224 {
225 	cpwd_toggleintr(p, index, WD_INTR_ON);
226 	cpwd_writew(WD_BLIMIT, p->devs[index].regs + WD_LIMIT);
227 }
228 
229 /* Timer method called to reset stopped watchdogs--
230  * because of the PLD bug on CP1400, we cannot mask
231  * interrupts within the PLD so me must continually
232  * reset the timers ad infinitum.
233  */
cpwd_brokentimer(struct timer_list * unused)234 static void cpwd_brokentimer(struct timer_list *unused)
235 {
236 	struct cpwd *p = cpwd_device;
237 	int id, tripped = 0;
238 
239 	/* kill a running timer instance, in case we
240 	 * were called directly instead of by kernel timer
241 	 */
242 	if (timer_pending(&cpwd_timer))
243 		del_timer(&cpwd_timer);
244 
245 	for (id = 0; id < WD_NUMDEVS; id++) {
246 		if (p->devs[id].runstatus & WD_STAT_BSTOP) {
247 			++tripped;
248 			cpwd_resetbrokentimer(p, id);
249 		}
250 	}
251 
252 	if (tripped) {
253 		/* there is at least one timer brokenstopped-- reschedule */
254 		cpwd_timer.expires = WD_BTIMEOUT;
255 		add_timer(&cpwd_timer);
256 	}
257 }
258 
259 /* Reset countdown timer with 'limit' value and continue countdown.
260  * This will not start a stopped timer.
261  */
cpwd_pingtimer(struct cpwd * p,int index)262 static void cpwd_pingtimer(struct cpwd *p, int index)
263 {
264 	if (cpwd_readb(p->devs[index].regs + WD_STATUS) & WD_S_RUNNING)
265 		cpwd_readw(p->devs[index].regs + WD_DCNTR);
266 }
267 
268 /* Stop a running watchdog timer-- the timer actually keeps
269  * running, but the interrupt is masked so that no action is
270  * taken upon expiration.
271  */
cpwd_stoptimer(struct cpwd * p,int index)272 static void cpwd_stoptimer(struct cpwd *p, int index)
273 {
274 	if (cpwd_readb(p->devs[index].regs + WD_STATUS) & WD_S_RUNNING) {
275 		cpwd_toggleintr(p, index, WD_INTR_OFF);
276 
277 		if (p->broken) {
278 			p->devs[index].runstatus |= WD_STAT_BSTOP;
279 			cpwd_brokentimer(NULL);
280 		}
281 	}
282 }
283 
284 /* Start a watchdog timer with the specified limit value
285  * If the watchdog is running, it will be restarted with
286  * the provided limit value.
287  *
288  * This function will enable interrupts on the specified
289  * watchdog.
290  */
cpwd_starttimer(struct cpwd * p,int index)291 static void cpwd_starttimer(struct cpwd *p, int index)
292 {
293 	if (p->broken)
294 		p->devs[index].runstatus &= ~WD_STAT_BSTOP;
295 
296 	p->devs[index].runstatus &= ~WD_STAT_SVCD;
297 
298 	cpwd_writew(p->devs[index].timeout, p->devs[index].regs + WD_LIMIT);
299 	cpwd_toggleintr(p, index, WD_INTR_ON);
300 }
301 
cpwd_getstatus(struct cpwd * p,int index)302 static int cpwd_getstatus(struct cpwd *p, int index)
303 {
304 	unsigned char stat = cpwd_readb(p->devs[index].regs + WD_STATUS);
305 	unsigned char intr = cpwd_readb(p->devs[index].regs + PLD_IMASK);
306 	unsigned char ret  = WD_STOPPED;
307 
308 	/* determine STOPPED */
309 	if (!stat)
310 		return ret;
311 
312 	/* determine EXPIRED vs FREERUN vs RUNNING */
313 	else if (WD_S_EXPIRED & stat) {
314 		ret = WD_EXPIRED;
315 	} else if (WD_S_RUNNING & stat) {
316 		if (intr & p->devs[index].intr_mask) {
317 			ret = WD_FREERUN;
318 		} else {
319 			/* Fudge WD_EXPIRED status for defective CP1400--
320 			 * IF timer is running
321 			 *	AND brokenstop is set
322 			 *	AND an interrupt has been serviced
323 			 * we are WD_EXPIRED.
324 			 *
325 			 * IF timer is running
326 			 *	AND brokenstop is set
327 			 *	AND no interrupt has been serviced
328 			 * we are WD_FREERUN.
329 			 */
330 			if (p->broken &&
331 			    (p->devs[index].runstatus & WD_STAT_BSTOP)) {
332 				if (p->devs[index].runstatus & WD_STAT_SVCD) {
333 					ret = WD_EXPIRED;
334 				} else {
335 					/* we could as well pretend
336 					 * we are expired */
337 					ret = WD_FREERUN;
338 				}
339 			} else {
340 				ret = WD_RUNNING;
341 			}
342 		}
343 	}
344 
345 	/* determine SERVICED */
346 	if (p->devs[index].runstatus & WD_STAT_SVCD)
347 		ret |= WD_SERVICED;
348 
349 	return ret;
350 }
351 
cpwd_interrupt(int irq,void * dev_id)352 static irqreturn_t cpwd_interrupt(int irq, void *dev_id)
353 {
354 	struct cpwd *p = dev_id;
355 
356 	/* Only WD0 will interrupt-- others are NMI and we won't
357 	 * see them here....
358 	 */
359 	spin_lock_irq(&p->lock);
360 
361 	cpwd_stoptimer(p, WD0_ID);
362 	p->devs[WD0_ID].runstatus |=  WD_STAT_SVCD;
363 
364 	spin_unlock_irq(&p->lock);
365 
366 	return IRQ_HANDLED;
367 }
368 
cpwd_open(struct inode * inode,struct file * f)369 static int cpwd_open(struct inode *inode, struct file *f)
370 {
371 	struct cpwd *p = cpwd_device;
372 
373 	mutex_lock(&cpwd_mutex);
374 	switch (iminor(inode)) {
375 	case WD0_MINOR:
376 	case WD1_MINOR:
377 	case WD2_MINOR:
378 		break;
379 
380 	default:
381 		mutex_unlock(&cpwd_mutex);
382 		return -ENODEV;
383 	}
384 
385 	/* Register IRQ on first open of device */
386 	if (!p->initialized) {
387 		if (request_irq(p->irq, &cpwd_interrupt,
388 				IRQF_SHARED, DRIVER_NAME, p)) {
389 			pr_err("Cannot register IRQ %d\n", p->irq);
390 			mutex_unlock(&cpwd_mutex);
391 			return -EBUSY;
392 		}
393 		p->initialized = true;
394 	}
395 
396 	mutex_unlock(&cpwd_mutex);
397 
398 	return stream_open(inode, f);
399 }
400 
cpwd_release(struct inode * inode,struct file * file)401 static int cpwd_release(struct inode *inode, struct file *file)
402 {
403 	return 0;
404 }
405 
cpwd_ioctl(struct file * file,unsigned int cmd,unsigned long arg)406 static long cpwd_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
407 {
408 	static const struct watchdog_info info = {
409 		.options		= WDIOF_SETTIMEOUT,
410 		.firmware_version	= 1,
411 		.identity		= DRIVER_NAME,
412 	};
413 	void __user *argp = (void __user *)arg;
414 	struct inode *inode = file_inode(file);
415 	int index = iminor(inode) - WD0_MINOR;
416 	struct cpwd *p = cpwd_device;
417 	int setopt = 0;
418 
419 	switch (cmd) {
420 	/* Generic Linux IOCTLs */
421 	case WDIOC_GETSUPPORT:
422 		if (copy_to_user(argp, &info, sizeof(struct watchdog_info)))
423 			return -EFAULT;
424 		break;
425 
426 	case WDIOC_GETSTATUS:
427 	case WDIOC_GETBOOTSTATUS:
428 		if (put_user(0, (int __user *)argp))
429 			return -EFAULT;
430 		break;
431 
432 	case WDIOC_KEEPALIVE:
433 		cpwd_pingtimer(p, index);
434 		break;
435 
436 	case WDIOC_SETOPTIONS:
437 		if (copy_from_user(&setopt, argp, sizeof(unsigned int)))
438 			return -EFAULT;
439 
440 		if (setopt & WDIOS_DISABLECARD) {
441 			if (p->enabled)
442 				return -EINVAL;
443 			cpwd_stoptimer(p, index);
444 		} else if (setopt & WDIOS_ENABLECARD) {
445 			cpwd_starttimer(p, index);
446 		} else {
447 			return -EINVAL;
448 		}
449 		break;
450 
451 	/* Solaris-compatible IOCTLs */
452 	case WIOCGSTAT:
453 		setopt = cpwd_getstatus(p, index);
454 		if (copy_to_user(argp, &setopt, sizeof(unsigned int)))
455 			return -EFAULT;
456 		break;
457 
458 	case WIOCSTART:
459 		cpwd_starttimer(p, index);
460 		break;
461 
462 	case WIOCSTOP:
463 		if (p->enabled)
464 			return -EINVAL;
465 
466 		cpwd_stoptimer(p, index);
467 		break;
468 
469 	default:
470 		return -EINVAL;
471 	}
472 
473 	return 0;
474 }
475 
cpwd_compat_ioctl(struct file * file,unsigned int cmd,unsigned long arg)476 static long cpwd_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
477 {
478 	return cpwd_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
479 }
480 
cpwd_write(struct file * file,const char __user * buf,size_t count,loff_t * ppos)481 static ssize_t cpwd_write(struct file *file, const char __user *buf,
482 			  size_t count, loff_t *ppos)
483 {
484 	struct inode *inode = file_inode(file);
485 	struct cpwd *p = cpwd_device;
486 	int index = iminor(inode);
487 
488 	if (count) {
489 		cpwd_pingtimer(p, index);
490 		return 1;
491 	}
492 
493 	return 0;
494 }
495 
cpwd_read(struct file * file,char __user * buffer,size_t count,loff_t * ppos)496 static ssize_t cpwd_read(struct file *file, char __user *buffer,
497 			 size_t count, loff_t *ppos)
498 {
499 	return -EINVAL;
500 }
501 
502 static const struct file_operations cpwd_fops = {
503 	.owner =		THIS_MODULE,
504 	.unlocked_ioctl =	cpwd_ioctl,
505 	.compat_ioctl =		cpwd_compat_ioctl,
506 	.open =			cpwd_open,
507 	.write =		cpwd_write,
508 	.read =			cpwd_read,
509 	.release =		cpwd_release,
510 	.llseek =		no_llseek,
511 };
512 
cpwd_probe(struct platform_device * op)513 static int cpwd_probe(struct platform_device *op)
514 {
515 	struct device_node *options;
516 	const char *str_prop;
517 	const void *prop_val;
518 	int i, err = -EINVAL;
519 	struct cpwd *p;
520 
521 	if (cpwd_device)
522 		return -EINVAL;
523 
524 	p = devm_kzalloc(&op->dev, sizeof(*p), GFP_KERNEL);
525 	if (!p)
526 		return -ENOMEM;
527 
528 	p->irq = op->archdata.irqs[0];
529 
530 	spin_lock_init(&p->lock);
531 
532 	p->regs = of_ioremap(&op->resource[0], 0,
533 			     4 * WD_TIMER_REGSZ, DRIVER_NAME);
534 	if (!p->regs) {
535 		pr_err("Unable to map registers\n");
536 		return -ENOMEM;
537 	}
538 
539 	options = of_find_node_by_path("/options");
540 	if (!options) {
541 		err = -ENODEV;
542 		pr_err("Unable to find /options node\n");
543 		goto out_iounmap;
544 	}
545 
546 	prop_val = of_get_property(options, "watchdog-enable?", NULL);
547 	p->enabled = (prop_val ? true : false);
548 
549 	prop_val = of_get_property(options, "watchdog-reboot?", NULL);
550 	p->reboot = (prop_val ? true : false);
551 
552 	str_prop = of_get_property(options, "watchdog-timeout", NULL);
553 	if (str_prop)
554 		p->timeout = simple_strtoul(str_prop, NULL, 10);
555 
556 	of_node_put(options);
557 
558 	/* CP1400s seem to have broken PLD implementations-- the
559 	 * interrupt_mask register cannot be written, so no timer
560 	 * interrupts can be masked within the PLD.
561 	 */
562 	str_prop = of_get_property(op->dev.of_node, "model", NULL);
563 	p->broken = (str_prop && !strcmp(str_prop, WD_BADMODEL));
564 
565 	if (!p->enabled)
566 		cpwd_toggleintr(p, -1, WD_INTR_OFF);
567 
568 	for (i = 0; i < WD_NUMDEVS; i++) {
569 		static const char *cpwd_names[] = { "RIC", "XIR", "POR" };
570 		static int *parms[] = { &wd0_timeout,
571 					&wd1_timeout,
572 					&wd2_timeout };
573 		struct miscdevice *mp = &p->devs[i].misc;
574 
575 		mp->minor = WD0_MINOR + i;
576 		mp->name = cpwd_names[i];
577 		mp->fops = &cpwd_fops;
578 
579 		p->devs[i].regs = p->regs + (i * WD_TIMER_REGSZ);
580 		p->devs[i].intr_mask = (WD0_INTR_MASK << i);
581 		p->devs[i].runstatus &= ~WD_STAT_BSTOP;
582 		p->devs[i].runstatus |= WD_STAT_INIT;
583 		p->devs[i].timeout = p->timeout;
584 		if (*parms[i])
585 			p->devs[i].timeout = *parms[i];
586 
587 		err = misc_register(&p->devs[i].misc);
588 		if (err) {
589 			pr_err("Could not register misc device for dev %d\n",
590 			       i);
591 			goto out_unregister;
592 		}
593 	}
594 
595 	if (p->broken) {
596 		timer_setup(&cpwd_timer, cpwd_brokentimer, 0);
597 		cpwd_timer.expires	= WD_BTIMEOUT;
598 
599 		pr_info("PLD defect workaround enabled for model %s\n",
600 			WD_BADMODEL);
601 	}
602 
603 	platform_set_drvdata(op, p);
604 	cpwd_device = p;
605 	return 0;
606 
607 out_unregister:
608 	for (i--; i >= 0; i--)
609 		misc_deregister(&p->devs[i].misc);
610 
611 out_iounmap:
612 	of_iounmap(&op->resource[0], p->regs, 4 * WD_TIMER_REGSZ);
613 
614 	return err;
615 }
616 
cpwd_remove(struct platform_device * op)617 static void cpwd_remove(struct platform_device *op)
618 {
619 	struct cpwd *p = platform_get_drvdata(op);
620 	int i;
621 
622 	for (i = 0; i < WD_NUMDEVS; i++) {
623 		misc_deregister(&p->devs[i].misc);
624 
625 		if (!p->enabled) {
626 			cpwd_stoptimer(p, i);
627 			if (p->devs[i].runstatus & WD_STAT_BSTOP)
628 				cpwd_resetbrokentimer(p, i);
629 		}
630 	}
631 
632 	if (p->broken)
633 		del_timer_sync(&cpwd_timer);
634 
635 	if (p->initialized)
636 		free_irq(p->irq, p);
637 
638 	of_iounmap(&op->resource[0], p->regs, 4 * WD_TIMER_REGSZ);
639 
640 	cpwd_device = NULL;
641 }
642 
643 static const struct of_device_id cpwd_match[] = {
644 	{
645 		.name = "watchdog",
646 	},
647 	{},
648 };
649 MODULE_DEVICE_TABLE(of, cpwd_match);
650 
651 static struct platform_driver cpwd_driver = {
652 	.driver = {
653 		.name = DRIVER_NAME,
654 		.of_match_table = cpwd_match,
655 	},
656 	.probe		= cpwd_probe,
657 	.remove_new	= cpwd_remove,
658 };
659 
660 module_platform_driver(cpwd_driver);
661