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/of_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
73struct 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
94static DEFINE_MUTEX(cpwd_mutex);
95static 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
159static struct timer_list cpwd_timer;
160
161static int wd0_timeout;
162static int wd1_timeout;
163static int wd2_timeout;
164
165module_param(wd0_timeout, int, 0);
166MODULE_PARM_DESC(wd0_timeout, "Default watchdog0 timeout in 1/10secs");
167module_param(wd1_timeout, int, 0);
168MODULE_PARM_DESC(wd1_timeout, "Default watchdog1 timeout in 1/10secs");
169module_param(wd2_timeout, int, 0);
170MODULE_PARM_DESC(wd2_timeout, "Default watchdog2 timeout in 1/10secs");
171
172MODULE_AUTHOR("Eric Brower <ebrower@usa.net>");
173MODULE_DESCRIPTION("Hardware watchdog driver for Sun Microsystems CP1400/1500");
174MODULE_LICENSE("GPL");
175MODULE_SUPPORTED_DEVICE("watchdog");
176
177static void cpwd_writew(u16 val, void __iomem *addr)
178{
179	writew(cpu_to_le16(val), addr);
180}
181static u16 cpwd_readw(void __iomem *addr)
182{
183	u16 val = readw(addr);
184
185	return le16_to_cpu(val);
186}
187
188static void cpwd_writeb(u8 val, void __iomem *addr)
189{
190	writeb(val, addr);
191}
192
193static u8 cpwd_readb(void __iomem *addr)
194{
195	return readb(addr);
196}
197
198/* Enable or disable watchdog interrupts
199 * Because of the CP1400 defect this should only be
200 * called during initialzation or by wd_[start|stop]timer()
201 *
202 * index	- sub-device index, or -1 for 'all'
203 * enable	- non-zero to enable interrupts, zero to disable
204 */
205static void cpwd_toggleintr(struct cpwd *p, int index, int enable)
206{
207	unsigned char curregs = cpwd_readb(p->regs + PLD_IMASK);
208	unsigned char setregs =
209		(index == -1) ?
210		(WD0_INTR_MASK | WD1_INTR_MASK | WD2_INTR_MASK) :
211		(p->devs[index].intr_mask);
212
213	if (enable == WD_INTR_ON)
214		curregs &= ~setregs;
215	else
216		curregs |= setregs;
217
218	cpwd_writeb(curregs, p->regs + PLD_IMASK);
219}
220
221/* Restarts timer with maximum limit value and
222 * does not unset 'brokenstop' value.
223 */
224static void cpwd_resetbrokentimer(struct cpwd *p, int index)
225{
226	cpwd_toggleintr(p, index, WD_INTR_ON);
227	cpwd_writew(WD_BLIMIT, p->devs[index].regs + WD_LIMIT);
228}
229
230/* Timer method called to reset stopped watchdogs--
231 * because of the PLD bug on CP1400, we cannot mask
232 * interrupts within the PLD so me must continually
233 * reset the timers ad infinitum.
234 */
235static void cpwd_brokentimer(struct timer_list *unused)
236{
237	struct cpwd *p = cpwd_device;
238	int id, tripped = 0;
239
240	/* kill a running timer instance, in case we
241	 * were called directly instead of by kernel timer
242	 */
243	if (timer_pending(&cpwd_timer))
244		del_timer(&cpwd_timer);
245
246	for (id = 0; id < WD_NUMDEVS; id++) {
247		if (p->devs[id].runstatus & WD_STAT_BSTOP) {
248			++tripped;
249			cpwd_resetbrokentimer(p, id);
250		}
251	}
252
253	if (tripped) {
254		/* there is at least one timer brokenstopped-- reschedule */
255		cpwd_timer.expires = WD_BTIMEOUT;
256		add_timer(&cpwd_timer);
257	}
258}
259
260/* Reset countdown timer with 'limit' value and continue countdown.
261 * This will not start a stopped timer.
262 */
263static void cpwd_pingtimer(struct cpwd *p, int index)
264{
265	if (cpwd_readb(p->devs[index].regs + WD_STATUS) & WD_S_RUNNING)
266		cpwd_readw(p->devs[index].regs + WD_DCNTR);
267}
268
269/* Stop a running watchdog timer-- the timer actually keeps
270 * running, but the interrupt is masked so that no action is
271 * taken upon expiration.
272 */
273static void cpwd_stoptimer(struct cpwd *p, int index)
274{
275	if (cpwd_readb(p->devs[index].regs + WD_STATUS) & WD_S_RUNNING) {
276		cpwd_toggleintr(p, index, WD_INTR_OFF);
277
278		if (p->broken) {
279			p->devs[index].runstatus |= WD_STAT_BSTOP;
280			cpwd_brokentimer(NULL);
281		}
282	}
283}
284
285/* Start a watchdog timer with the specified limit value
286 * If the watchdog is running, it will be restarted with
287 * the provided limit value.
288 *
289 * This function will enable interrupts on the specified
290 * watchdog.
291 */
292static void cpwd_starttimer(struct cpwd *p, int index)
293{
294	if (p->broken)
295		p->devs[index].runstatus &= ~WD_STAT_BSTOP;
296
297	p->devs[index].runstatus &= ~WD_STAT_SVCD;
298
299	cpwd_writew(p->devs[index].timeout, p->devs[index].regs + WD_LIMIT);
300	cpwd_toggleintr(p, index, WD_INTR_ON);
301}
302
303static int cpwd_getstatus(struct cpwd *p, int index)
304{
305	unsigned char stat = cpwd_readb(p->devs[index].regs + WD_STATUS);
306	unsigned char intr = cpwd_readb(p->devs[index].regs + PLD_IMASK);
307	unsigned char ret  = WD_STOPPED;
308
309	/* determine STOPPED */
310	if (!stat)
311		return ret;
312
313	/* determine EXPIRED vs FREERUN vs RUNNING */
314	else if (WD_S_EXPIRED & stat) {
315		ret = WD_EXPIRED;
316	} else if (WD_S_RUNNING & stat) {
317		if (intr & p->devs[index].intr_mask) {
318			ret = WD_FREERUN;
319		} else {
320			/* Fudge WD_EXPIRED status for defective CP1400--
321			 * IF timer is running
322			 *	AND brokenstop is set
323			 *	AND an interrupt has been serviced
324			 * we are WD_EXPIRED.
325			 *
326			 * IF timer is running
327			 *	AND brokenstop is set
328			 *	AND no interrupt has been serviced
329			 * we are WD_FREERUN.
330			 */
331			if (p->broken &&
332			    (p->devs[index].runstatus & WD_STAT_BSTOP)) {
333				if (p->devs[index].runstatus & WD_STAT_SVCD) {
334					ret = WD_EXPIRED;
335				} else {
336					/* we could as well pretend
337					 * we are expired */
338					ret = WD_FREERUN;
339				}
340			} else {
341				ret = WD_RUNNING;
342			}
343		}
344	}
345
346	/* determine SERVICED */
347	if (p->devs[index].runstatus & WD_STAT_SVCD)
348		ret |= WD_SERVICED;
349
350	return ret;
351}
352
353static irqreturn_t cpwd_interrupt(int irq, void *dev_id)
354{
355	struct cpwd *p = dev_id;
356
357	/* Only WD0 will interrupt-- others are NMI and we won't
358	 * see them here....
359	 */
360	spin_lock_irq(&p->lock);
361
362	cpwd_stoptimer(p, WD0_ID);
363	p->devs[WD0_ID].runstatus |=  WD_STAT_SVCD;
364
365	spin_unlock_irq(&p->lock);
366
367	return IRQ_HANDLED;
368}
369
370static int cpwd_open(struct inode *inode, struct file *f)
371{
372	struct cpwd *p = cpwd_device;
373
374	mutex_lock(&cpwd_mutex);
375	switch (iminor(inode)) {
376	case WD0_MINOR:
377	case WD1_MINOR:
378	case WD2_MINOR:
379		break;
380
381	default:
382		mutex_unlock(&cpwd_mutex);
383		return -ENODEV;
384	}
385
386	/* Register IRQ on first open of device */
387	if (!p->initialized) {
388		if (request_irq(p->irq, &cpwd_interrupt,
389				IRQF_SHARED, DRIVER_NAME, p)) {
390			pr_err("Cannot register IRQ %d\n", p->irq);
391			mutex_unlock(&cpwd_mutex);
392			return -EBUSY;
393		}
394		p->initialized = true;
395	}
396
397	mutex_unlock(&cpwd_mutex);
398
399	return stream_open(inode, f);
400}
401
402static int cpwd_release(struct inode *inode, struct file *file)
403{
404	return 0;
405}
406
407static long cpwd_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
408{
409	static const struct watchdog_info info = {
410		.options		= WDIOF_SETTIMEOUT,
411		.firmware_version	= 1,
412		.identity		= DRIVER_NAME,
413	};
414	void __user *argp = (void __user *)arg;
415	struct inode *inode = file_inode(file);
416	int index = iminor(inode) - WD0_MINOR;
417	struct cpwd *p = cpwd_device;
418	int setopt = 0;
419
420	switch (cmd) {
421	/* Generic Linux IOCTLs */
422	case WDIOC_GETSUPPORT:
423		if (copy_to_user(argp, &info, sizeof(struct watchdog_info)))
424			return -EFAULT;
425		break;
426
427	case WDIOC_GETSTATUS:
428	case WDIOC_GETBOOTSTATUS:
429		if (put_user(0, (int __user *)argp))
430			return -EFAULT;
431		break;
432
433	case WDIOC_KEEPALIVE:
434		cpwd_pingtimer(p, index);
435		break;
436
437	case WDIOC_SETOPTIONS:
438		if (copy_from_user(&setopt, argp, sizeof(unsigned int)))
439			return -EFAULT;
440
441		if (setopt & WDIOS_DISABLECARD) {
442			if (p->enabled)
443				return -EINVAL;
444			cpwd_stoptimer(p, index);
445		} else if (setopt & WDIOS_ENABLECARD) {
446			cpwd_starttimer(p, index);
447		} else {
448			return -EINVAL;
449		}
450		break;
451
452	/* Solaris-compatible IOCTLs */
453	case WIOCGSTAT:
454		setopt = cpwd_getstatus(p, index);
455		if (copy_to_user(argp, &setopt, sizeof(unsigned int)))
456			return -EFAULT;
457		break;
458
459	case WIOCSTART:
460		cpwd_starttimer(p, index);
461		break;
462
463	case WIOCSTOP:
464		if (p->enabled)
465			return -EINVAL;
466
467		cpwd_stoptimer(p, index);
468		break;
469
470	default:
471		return -EINVAL;
472	}
473
474	return 0;
475}
476
477static long cpwd_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
478{
479	return cpwd_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
480}
481
482static ssize_t cpwd_write(struct file *file, const char __user *buf,
483			  size_t count, loff_t *ppos)
484{
485	struct inode *inode = file_inode(file);
486	struct cpwd *p = cpwd_device;
487	int index = iminor(inode);
488
489	if (count) {
490		cpwd_pingtimer(p, index);
491		return 1;
492	}
493
494	return 0;
495}
496
497static ssize_t cpwd_read(struct file *file, char __user *buffer,
498			 size_t count, loff_t *ppos)
499{
500	return -EINVAL;
501}
502
503static const struct file_operations cpwd_fops = {
504	.owner =		THIS_MODULE,
505	.unlocked_ioctl =	cpwd_ioctl,
506	.compat_ioctl =		cpwd_compat_ioctl,
507	.open =			cpwd_open,
508	.write =		cpwd_write,
509	.read =			cpwd_read,
510	.release =		cpwd_release,
511	.llseek =		no_llseek,
512};
513
514static int cpwd_probe(struct platform_device *op)
515{
516	struct device_node *options;
517	const char *str_prop;
518	const void *prop_val;
519	int i, err = -EINVAL;
520	struct cpwd *p;
521
522	if (cpwd_device)
523		return -EINVAL;
524
525	p = devm_kzalloc(&op->dev, sizeof(*p), GFP_KERNEL);
526	if (!p)
527		return -ENOMEM;
528
529	p->irq = op->archdata.irqs[0];
530
531	spin_lock_init(&p->lock);
532
533	p->regs = of_ioremap(&op->resource[0], 0,
534			     4 * WD_TIMER_REGSZ, DRIVER_NAME);
535	if (!p->regs) {
536		pr_err("Unable to map registers\n");
537		return -ENOMEM;
538	}
539
540	options = of_find_node_by_path("/options");
541	if (!options) {
542		err = -ENODEV;
543		pr_err("Unable to find /options node\n");
544		goto out_iounmap;
545	}
546
547	prop_val = of_get_property(options, "watchdog-enable?", NULL);
548	p->enabled = (prop_val ? true : false);
549
550	prop_val = of_get_property(options, "watchdog-reboot?", NULL);
551	p->reboot = (prop_val ? true : false);
552
553	str_prop = of_get_property(options, "watchdog-timeout", NULL);
554	if (str_prop)
555		p->timeout = simple_strtoul(str_prop, NULL, 10);
556
557	of_node_put(options);
558
559	/* CP1400s seem to have broken PLD implementations-- the
560	 * interrupt_mask register cannot be written, so no timer
561	 * interrupts can be masked within the PLD.
562	 */
563	str_prop = of_get_property(op->dev.of_node, "model", NULL);
564	p->broken = (str_prop && !strcmp(str_prop, WD_BADMODEL));
565
566	if (!p->enabled)
567		cpwd_toggleintr(p, -1, WD_INTR_OFF);
568
569	for (i = 0; i < WD_NUMDEVS; i++) {
570		static const char *cpwd_names[] = { "RIC", "XIR", "POR" };
571		static int *parms[] = { &wd0_timeout,
572					&wd1_timeout,
573					&wd2_timeout };
574		struct miscdevice *mp = &p->devs[i].misc;
575
576		mp->minor = WD0_MINOR + i;
577		mp->name = cpwd_names[i];
578		mp->fops = &cpwd_fops;
579
580		p->devs[i].regs = p->regs + (i * WD_TIMER_REGSZ);
581		p->devs[i].intr_mask = (WD0_INTR_MASK << i);
582		p->devs[i].runstatus &= ~WD_STAT_BSTOP;
583		p->devs[i].runstatus |= WD_STAT_INIT;
584		p->devs[i].timeout = p->timeout;
585		if (*parms[i])
586			p->devs[i].timeout = *parms[i];
587
588		err = misc_register(&p->devs[i].misc);
589		if (err) {
590			pr_err("Could not register misc device for dev %d\n",
591			       i);
592			goto out_unregister;
593		}
594	}
595
596	if (p->broken) {
597		timer_setup(&cpwd_timer, cpwd_brokentimer, 0);
598		cpwd_timer.expires	= WD_BTIMEOUT;
599
600		pr_info("PLD defect workaround enabled for model %s\n",
601			WD_BADMODEL);
602	}
603
604	platform_set_drvdata(op, p);
605	cpwd_device = p;
606	return 0;
607
608out_unregister:
609	for (i--; i >= 0; i--)
610		misc_deregister(&p->devs[i].misc);
611
612out_iounmap:
613	of_iounmap(&op->resource[0], p->regs, 4 * WD_TIMER_REGSZ);
614
615	return err;
616}
617
618static int cpwd_remove(struct platform_device *op)
619{
620	struct cpwd *p = platform_get_drvdata(op);
621	int i;
622
623	for (i = 0; i < WD_NUMDEVS; i++) {
624		misc_deregister(&p->devs[i].misc);
625
626		if (!p->enabled) {
627			cpwd_stoptimer(p, i);
628			if (p->devs[i].runstatus & WD_STAT_BSTOP)
629				cpwd_resetbrokentimer(p, i);
630		}
631	}
632
633	if (p->broken)
634		del_timer_sync(&cpwd_timer);
635
636	if (p->initialized)
637		free_irq(p->irq, p);
638
639	of_iounmap(&op->resource[0], p->regs, 4 * WD_TIMER_REGSZ);
640
641	cpwd_device = NULL;
642
643	return 0;
644}
645
646static const struct of_device_id cpwd_match[] = {
647	{
648		.name = "watchdog",
649	},
650	{},
651};
652MODULE_DEVICE_TABLE(of, cpwd_match);
653
654static struct platform_driver cpwd_driver = {
655	.driver = {
656		.name = DRIVER_NAME,
657		.of_match_table = cpwd_match,
658	},
659	.probe		= cpwd_probe,
660	.remove		= cpwd_remove,
661};
662
663module_platform_driver(cpwd_driver);
664