aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/watchdog/mpc8xxx_wdt.c
blob: ea438ad530559c401cba603e970a5564234c9092 (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
/*
 * mpc8xxx_wdt.c - MPC8xx/MPC83xx/MPC86xx watchdog userspace interface
 *
 * Authors: Dave Updegraff <dave@cray.org>
 * 	    Kumar Gala <galak@kernel.crashing.org>
 * 		Attribution: from 83xx_wst: Florian Schirmer <jolt@tuxbox.org>
 * 				..and from sc520_wdt
 * Copyright (c) 2008  MontaVista Software, Inc.
 *                     Anton Vorontsov <avorontsov@ru.mvista.com>
 *
 * Note: it appears that you can only actually ENABLE or DISABLE the thing
 * once after POR. Once enabled, you cannot disable, and vice versa.
 *
 * This program is free software; you can redistribute  it and/or modify it
 * under  the terms of  the GNU General  Public License as published by the
 * Free Software Foundation;  either version 2 of the  License, or (at your
 * option) any later version.
 */

#include <linux/fs.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/timer.h>
#include <linux/miscdevice.h>
#include <linux/of_platform.h>
#include <linux/module.h>
#include <linux/watchdog.h>
#include <linux/io.h>
#include <linux/uaccess.h>
#include <sysdev/fsl_soc.h>

struct mpc8xxx_wdt {
	__be32 res0;
	__be32 swcrr; /* System watchdog control register */
#define SWCRR_SWTC 0xFFFF0000 /* Software Watchdog Time Count. */
#define SWCRR_SWEN 0x00000004 /* Watchdog Enable bit. */
#define SWCRR_SWRI 0x00000002 /* Software Watchdog Reset/Interrupt Select bit.*/
#define SWCRR_SWPR 0x00000001 /* Software Watchdog Counter Prescale bit. */
	__be32 swcnr; /* System watchdog count register */
	u8 res1[2];
	__be16 swsrr; /* System watchdog service register */
	u8 res2[0xF0];
};

struct mpc8xxx_wdt_type {
	int prescaler;
	bool hw_enabled;
};

static struct mpc8xxx_wdt __iomem *wd_base;
static int mpc8xxx_wdt_init_late(void);

static u16 timeout = 0xffff;
module_param(timeout, ushort, 0);
MODULE_PARM_DESC(timeout,
	"Watchdog timeout in ticks. (0<timeout<65536, default=65535)");

static int reset = 1;
module_param(reset, bool, 0);
MODULE_PARM_DESC(reset,
	"Watchdog Interrupt/Reset Mode. 0 = interrupt, 1 = reset");

static int nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, int, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
		 "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

/*
 * We always prescale, but if someone really doesn't want to they can set this
 * to 0
 */
static int prescale = 1;
static unsigned int timeout_sec;

static unsigned long wdt_is_open;
static DEFINE_SPINLOCK(wdt_spinlock);

static void mpc8xxx_wdt_keepalive(void)
{
	/* Ping the WDT */
	spin_lock(&wdt_spinlock);
	out_be16(&wd_base->swsrr, 0x556c);
	out_be16(&wd_base->swsrr, 0xaa39);
	spin_unlock(&wdt_spinlock);
}

static void mpc8xxx_wdt_timer_ping(unsigned long arg);
static DEFINE_TIMER(wdt_timer, mpc8xxx_wdt_timer_ping, 0, 0);

static void mpc8xxx_wdt_timer_ping(unsigned long arg)
{
	mpc8xxx_wdt_keepalive();
	/* We're pinging it twice faster than needed, just to be sure. */
	mod_timer(&wdt_timer, jiffies + HZ * timeout_sec / 2);
}

static void mpc8xxx_wdt_pr_warn(const char *msg)
{
	pr_crit("mpc8xxx_wdt: %s, expect the %s soon!\n", msg,
		reset ? "reset" : "machine check exception");
}

static ssize_t mpc8xxx_wdt_write(struct file *file, const char __user *buf,
				 size_t count, loff_t *ppos)
{
	if (count)
		mpc8xxx_wdt_keepalive();
	return count;
}

static int mpc8xxx_wdt_open(struct inode *inode, struct file *file)
{
	u32 tmp = SWCRR_SWEN;
	if (test_and_set_bit(0, &wdt_is_open))
		return -EBUSY;

	/* Once we start the watchdog we can't stop it */
	if (nowayout)
		__module_get(THIS_MODULE);

	/* Good, fire up the show */
	if (prescale)
		tmp |= SWCRR_SWPR;
	if (reset)
		tmp |= SWCRR_SWRI;

	tmp |= timeout << 16;

	out_be32(&wd_base->swcrr, tmp);

	del_timer_sync(&wdt_timer);

	return nonseekable_open(inode, file);
}

static int mpc8xxx_wdt_release(struct inode *inode, struct file *file)
{
	if (!nowayout)
		mpc8xxx_wdt_timer_ping(0);
	else
		mpc8xxx_wdt_pr_warn("watchdog closed");
	clear_bit(0, &wdt_is_open);
	return 0;
}

static long mpc8xxx_wdt_ioctl(struct file *file, unsigned int cmd,
							unsigned long arg)
{
	void __user *argp = (void __user *)arg;
	int __user *p = argp;
	static const struct watchdog_info ident = {
		.options = WDIOF_KEEPALIVEPING,
		.firmware_version = 1,
		.identity = "MPC8xxx",
	};

	switch (cmd) {
	case WDIOC_GETSUPPORT:
		return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
	case WDIOC_GETSTATUS:
	case WDIOC_GETBOOTSTATUS:
		return put_user(0, p);
	case WDIOC_KEEPALIVE:
		mpc8xxx_wdt_keepalive();
		return 0;
	case WDIOC_GETTIMEOUT:
		return put_user(timeout_sec, p);
	default:
		return -ENOTTY;
	}
}

static const struct file_operations mpc8xxx_wdt_fops = {
	.owner		= THIS_MODULE,
	.llseek		= no_llseek,
	.write		= mpc8xxx_wdt_write,
	.unlocked_ioctl	= mpc8xxx_wdt_ioctl,
	.open		= mpc8xxx_wdt_open,
	.release	= mpc8xxx_wdt_release,
};

static struct miscdevice mpc8xxx_wdt_miscdev = {
	.minor	= WATCHDOG_MINOR,
	.name	= "watchdog",
	.fops	= &mpc8xxx_wdt_fops,
};

static int __devinit mpc8xxx_wdt_probe(struct platform_device *ofdev)
{
	int ret;
	struct device_node *np = ofdev->dev.of_node;
	struct mpc8xxx_wdt_type *wdt_type;
	u32 freq = fsl_get_sys_freq();
	bool enabled;

	if (!ofdev->dev.of_match)
		return -EINVAL;
	wdt_type = match->data;

	if (!freq || freq == -1)
		return -EINVAL;

	wd_base = of_iomap(np, 0);
	if (!wd_base)
		return -ENOMEM;

	enabled = in_be32(&wd_base->swcrr) & SWCRR_SWEN;
	if (!enabled && wdt_type->hw_enabled) {
		pr_info("mpc8xxx_wdt: could not be enabled in software\n");
		ret = -ENOSYS;
		goto err_unmap;
	}

	/* Calculate the timeout in seconds */
	if (prescale)
		timeout_sec = (timeout * wdt_type->prescaler) / freq;
	else
		timeout_sec = timeout / freq;

#ifdef MODULE
	ret = mpc8xxx_wdt_init_late();
	if (ret)
		goto err_unmap;
#endif

	pr_info("WDT driver for MPC8xxx initialized. mode:%s timeout=%d "
		"(%d seconds)\n", reset ? "reset" : "interrupt", timeout,
		timeout_sec);

	/*
	 * If the watchdog was previously enabled or we're running on
	 * MPC8xxx, we should ping the wdt from the kernel until the
	 * userspace handles it.
	 */
	if (enabled)
		mpc8xxx_wdt_timer_ping(0);
	return 0;
err_unmap:
	iounmap(wd_base);
	wd_base = NULL;
	return ret;
}

static int __devexit mpc8xxx_wdt_remove(struct platform_device *ofdev)
{
	mpc8xxx_wdt_pr_warn("watchdog removed");
	del_timer_sync(&wdt_timer);
	misc_deregister(&mpc8xxx_wdt_miscdev);
	iounmap(wd_base);

	return 0;
}

static const struct of_device_id mpc8xxx_wdt_match[] = {
	{
		.compatible = "mpc83xx_wdt",
		.data = &(struct mpc8xxx_wdt_type) {
			.prescaler = 0x10000,
		},
	},
	{
		.compatible = "fsl,mpc8610-wdt",
		.data = &(struct mpc8xxx_wdt_type) {
			.prescaler = 0x10000,
			.hw_enabled = true,
		},
	},
	{
		.compatible = "fsl,mpc823-wdt",
		.data = &(struct mpc8xxx_wdt_type) {
			.prescaler = 0x800,
		},
	},
	{},
};
MODULE_DEVICE_TABLE(of, mpc8xxx_wdt_match);

static struct platform_driver mpc8xxx_wdt_driver = {
	.probe		= mpc8xxx_wdt_probe,
	.remove		= __devexit_p(mpc8xxx_wdt_remove),
	.driver = {
		.name = "mpc8xxx_wdt",
		.owner = THIS_MODULE,
		.of_match_table = mpc8xxx_wdt_match,
	},
};

/*
 * We do wdt initialization in two steps: arch_initcall probes the wdt
 * very early to start pinging the watchdog (misc devices are not yet
 * available), and later module_init() just registers the misc device.
 */
static int mpc8xxx_wdt_init_late(void)
{
	int ret;

	if (!wd_base)
		return -ENODEV;

	ret = misc_register(&mpc8xxx_wdt_miscdev);
	if (ret) {
		pr_err("cannot register miscdev on minor=%d (err=%d)\n",
			WATCHDOG_MINOR, ret);
		return ret;
	}
	return 0;
}
#ifndef MODULE
module_init(mpc8xxx_wdt_init_late);
#endif

static int __init mpc8xxx_wdt_init(void)
{
	return platform_driver_register(&mpc8xxx_wdt_driver);
}
arch_initcall(mpc8xxx_wdt_init);

static void __exit mpc8xxx_wdt_exit(void)
{
	platform_driver_unregister(&mpc8xxx_wdt_driver);
}
module_exit(mpc8xxx_wdt_exit);

MODULE_AUTHOR("Dave Updegraff, Kumar Gala");
MODULE_DESCRIPTION("Driver for watchdog timer in MPC8xx/MPC83xx/MPC86xx "
		   "uProcessors");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);