summaryrefslogtreecommitdiffstats
path: root/drivers/watchdog/sb_wdog.c
blob: c8b544ce77fb05fc1b0423847e88ed22a4b3ea18 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
/*
 * Watchdog driver for SiByte SB1 SoCs
 *
 * Copyright (C) 2007 OnStor, Inc. * Andrew Sharp <andy.sharp@onstor.com>
 *
 * This driver is intended to make the second of two hardware watchdogs
 * on the Sibyte 12XX and 11XX SoCs available to the user.  There are two
 * such devices available on the SoC, but it seems that there isn't an
 * enumeration class for watchdogs in Linux like there is for RTCs.
 * The second is used rather than the first because it uses IRQ 1,
 * thereby avoiding all that IRQ 0 problematic nonsense.
 *
 * I have not tried this driver on a 1480 processor; it might work
 * just well enough to really screw things up.
 *
 * It is a simple timer, and there is an interrupt that is raised the
 * first time the timer expires.  The second time it expires, the chip
 * is reset and there is no way to redirect that NMI.  Which could
 * be problematic in some cases where this chip is sitting on the HT
 * bus and has just taken responsibility for providing a cache block.
 * Since the reset can't be redirected to the external reset pin, it is
 * possible that other HT connected processors might hang and not reset.
 * For Linux, a soft reset would probably be even worse than a hard reset.
 * There you have it.
 *
 * The timer takes 23 bits of a 64 bit register (?) as a count value,
 * and decrements the count every microsecond, for a max value of
 * 0x7fffff usec or about 8.3ish seconds.
 *
 * This watchdog borrows some user semantics from the softdog driver,
 * in that if you close the fd, it leaves the watchdog running, unless
 * you previously wrote a 'V' to the fd, in which case it disables
 * the watchdog when you close the fd like some other drivers.
 *
 * Based on various other watchdog drivers, which are probably all
 * loosely based on something Alan Cox wrote years ago.
 *
 *	(c) Copyright 1996 Alan Cox <alan@redhat.com>, All Rights Reserved.
 *				http://www.redhat.com
 *
 *	This program is free software; you can redistribute it and/or
 *	modify it under the terms of the GNU General Public License
 *	version 1 or 2 as published by the Free Software Foundation.
 *
 */
#include <linux/module.h>
#include <linux/io.h>
#include <linux/uaccess.h>
#include <linux/fs.h>
#include <linux/reboot.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/interrupt.h>

#include <asm/sibyte/sb1250.h>
#include <asm/sibyte/sb1250_regs.h>
#include <asm/sibyte/sb1250_int.h>
#include <asm/sibyte/sb1250_scd.h>

static DEFINE_SPINLOCK(sbwd_lock);

/*
 * set the initial count value of a timer
 *
 * wdog is the iomem address of the cfg register
 */
void sbwdog_set(char __iomem *wdog, unsigned long t)
{
	spin_lock(&sbwd_lock);
	__raw_writeb(0, wdog - 0x10);
	__raw_writeq(t & 0x7fffffUL, wdog);
	spin_unlock(&sbwd_lock);
}

/*
 * cause the timer to [re]load it's initial count and start counting
 * all over again
 *
 * wdog is the iomem address of the cfg register
 */
void sbwdog_pet(char __iomem *wdog)
{
	spin_lock(&sbwd_lock);
	__raw_writeb(__raw_readb(wdog) | 1, wdog);
	spin_unlock(&sbwd_lock);
}

static unsigned long sbwdog_gate; /* keeps it to one thread only */
static char __iomem *kern_dog = (char __iomem *)(IO_BASE + (A_SCD_WDOG_CFG_0));
static char __iomem *user_dog = (char __iomem *)(IO_BASE + (A_SCD_WDOG_CFG_1));
static unsigned long timeout = 0x7fffffUL;	/* useconds: 8.3ish secs. */
static int expect_close;

static const struct watchdog_info ident = {
	.options	= WDIOF_CARDRESET | WDIOF_SETTIMEOUT |
						WDIOF_KEEPALIVEPING,
	.identity	= "SiByte Watchdog",
};

/*
 * Allow only a single thread to walk the dog
 */
static int sbwdog_open(struct inode *inode, struct file *file)
{
	nonseekable_open(inode, file);
	if (test_and_set_bit(0, &sbwdog_gate))
		return -EBUSY;
	__module_get(THIS_MODULE);

	/*
	 * Activate the timer
	 */
	sbwdog_set(user_dog, timeout);
	__raw_writeb(1, user_dog);

	return 0;
}

/*
 * Put the dog back in the kennel.
 */
static int sbwdog_release(struct inode *inode, struct file *file)
{
	if (expect_close == 42) {
		__raw_writeb(0, user_dog);
		module_put(THIS_MODULE);
	} else {
		printk(KERN_CRIT
			"%s: Unexpected close, not stopping watchdog!\n",
						ident.identity);
		sbwdog_pet(user_dog);
	}
	clear_bit(0, &sbwdog_gate);
	expect_close = 0;

	return 0;
}

/*
 * 42 - the answer
 */
static ssize_t sbwdog_write(struct file *file, const char __user *data,
			size_t len, loff_t *ppos)
{
	int i;

	if (len) {
		/*
		 * restart the timer
		 */
		expect_close = 0;

		for (i = 0; i != len; i++) {
			char c;

			if (get_user(c, data + i))
				return -EFAULT;
			if (c == 'V')
				expect_close = 42;
		}
		sbwdog_pet(user_dog);
	}

	return len;
}

static long sbwdog_ioctl(struct file *file, unsigned int cmd,
						unsigned long arg)
{
	int ret = -ENOTTY;
	unsigned long time;
	void __user *argp = (void __user *)arg;
	int __user *p = argp;

	switch (cmd) {
	case WDIOC_GETSUPPORT:
		ret = copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
		break;

	case WDIOC_GETSTATUS:
	case WDIOC_GETBOOTSTATUS:
		ret = put_user(0, p);
		break;

	case WDIOC_SETTIMEOUT:
		ret = get_user(time, p);
		if (ret)
			break;

		time *= 1000000;
		if (time > 0x7fffffUL) {
			ret = -EINVAL;
			break;
		}
		timeout = time;
		sbwdog_set(user_dog, timeout);
		sbwdog_pet(user_dog);

	case WDIOC_GETTIMEOUT:
		/*
		 * get the remaining count from the ... count register
		 * which is 1*8 before the config register
		 */
		ret = put_user(__raw_readq(user_dog - 8) / 1000000, p);
		break;

	case WDIOC_KEEPALIVE:
		sbwdog_pet(user_dog);
		ret = 0;
		break;
	}
	return ret;
}

/*
 *	Notifier for system down
 */
static int
sbwdog_notify_sys(struct notifier_block *this, unsigned long code, void *erf)
{
	if (code == SYS_DOWN || code == SYS_HALT) {
		/*
		 * sit and sit
		 */
		__raw_writeb(0, user_dog);
		__raw_writeb(0, kern_dog);
	}

	return NOTIFY_DONE;
}

static const struct file_operations sbwdog_fops = {
	.owner		= THIS_MODULE,
	.llseek		= no_llseek,
	.write		= sbwdog_write,
	.unlocked_ioctl	= sbwdog_ioctl,
	.open		= sbwdog_open,
	.release	= sbwdog_release,
};

static struct miscdevice sbwdog_miscdev = {
	.minor		= WATCHDOG_MINOR,
	.name		= "watchdog",
	.fops		= &sbwdog_fops,
};

static struct notifier_block sbwdog_notifier = {
	.notifier_call	= sbwdog_notify_sys,
};

/*
 * interrupt handler
 *
 * doesn't do a whole lot for user, but oh so cleverly written so kernel
 * code can use it to re-up the watchdog, thereby saving the kernel from
 * having to create and maintain a timer, just to tickle another timer,
 * which is just so wrong.
 */
irqreturn_t sbwdog_interrupt(int irq, void *addr)
{
	unsigned long wd_init;
	char *wd_cfg_reg = (char *)addr;
	u8 cfg;

	cfg = __raw_readb(wd_cfg_reg);
	wd_init = __raw_readq(wd_cfg_reg - 8) & 0x7fffff;

	/*
	 * if it's the second watchdog timer, it's for those users
	 */
	if (wd_cfg_reg == user_dog)
		printk(KERN_CRIT
			"%s in danger of initiating system reset in %ld.%01ld seconds\n",
			ident.identity, wd_init / 1000000, (wd_init / 100000) % 10);
	else
		cfg |= 1;

	__raw_writeb(cfg, wd_cfg_reg);

	return IRQ_HANDLED;
}

static int __init sbwdog_init(void)
{
	int ret;

	/*
	 * register a reboot notifier
	 */
	ret = register_reboot_notifier(&sbwdog_notifier);
	if (ret) {
		printk(KERN_ERR
			"%s: cannot register reboot notifier (err=%d)\n",
						ident.identity, ret);
		return ret;
	}

	/*
	 * get the resources
	 */

	ret = request_irq(1, sbwdog_interrupt, IRQF_DISABLED | IRQF_SHARED,
		ident.identity, (void *)user_dog);
	if (ret) {
		printk(KERN_ERR "%s: failed to request irq 1 - %d\n",
						ident.identity, ret);
		return ret;
	}

	ret = misc_register(&sbwdog_miscdev);
	if (ret == 0) {
		printk(KERN_INFO "%s: timeout is %ld.%ld secs\n",
				ident.identity,
				timeout / 1000000, (timeout / 100000) % 10);
	} else
		free_irq(1, (void *)user_dog);
	return ret;
}

static void __exit sbwdog_exit(void)
{
	misc_deregister(&sbwdog_miscdev);
}

module_init(sbwdog_init);
module_exit(sbwdog_exit);

MODULE_AUTHOR("Andrew Sharp <andy.sharp@onstor.com>");
MODULE_DESCRIPTION("SiByte Watchdog");

module_param(timeout, ulong, 0);
MODULE_PARM_DESC(timeout,
      "Watchdog timeout in microseconds (max/default 8388607 or 8.3ish secs)");

MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);

/*
 * example code that can be put in a platform code area to utilize the
 * first watchdog timer for the kernels own purpose.

void platform_wd_setup(void)
{
	int ret;

	ret = request_irq(1, sbwdog_interrupt, IRQF_DISABLED | IRQF_SHARED,
		"Kernel Watchdog", IOADDR(A_SCD_WDOG_CFG_0));
	if (ret) {
		printk(KERN_CRIT
		  "Watchdog IRQ zero(0) failed to be requested - %d\n", ret);
	}
}


 */