shwdt.c 12.6 KB
Newer Older
L
Linus Torvalds 已提交
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
/*
 * drivers/char/watchdog/shwdt.c
 *
 * Watchdog driver for integrated watchdog in the SuperH processors.
 *
 * Copyright (C) 2001, 2002, 2003 Paul Mundt <lethal@linux-sh.org>
 *
 * 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.
 *
 * 14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
 *     Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
 *
 * 19-Apr-2002 Rob Radez <rob@osinvestor.com>
 *     Added expect close support, made emulated timeout runtime changeable
 *     general cleanups, add some ioctls
 */
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/reboot.h>
#include <linux/notifier.h>
#include <linux/ioport.h>
#include <linux/fs.h>
30
#include <linux/mm.h>
L
Linus Torvalds 已提交
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
#include <asm/io.h>
#include <asm/uaccess.h>
#include <asm/watchdog.h>

#define PFX "shwdt: "

/*
 * Default clock division ratio is 5.25 msecs. For an additional table of
 * values, consult the asm-sh/watchdog.h. Overload this at module load
 * time.
 *
 * In order for this to work reliably we need to have HZ set to 1000 or
 * something quite higher than 100 (or we need a proper high-res timer
 * implementation that will deal with this properly), otherwise the 10ms
 * resolution of a jiffy is enough to trigger the overflow. For things like
 * the SH-4 and SH-5, this isn't necessarily that big of a problem, though
 * for the SH-2 and SH-3, this isn't recommended unless the WDT is absolutely
 * necssary.
 *
 * As a result of this timing problem, the only modes that are particularly
 * feasible are the 4096 and the 2048 divisors, which yeild 5.25 and 2.62ms
 * overflow periods respectively.
 *
 * Also, since we can't really expect userspace to be responsive enough
 * before the overflow happens, we maintain two seperate timers .. One in
 * the kernel for clearing out WOVF every 2ms or so (again, this depends on
 * HZ == 1000), and another for monitoring userspace writes to the WDT device.
 *
 * As such, we currently use a configurable heartbeat interval which defaults
 * to 30s. In this case, the userspace daemon is only responsible for periodic
 * writes to the device before the next heartbeat is scheduled. If the daemon
 * misses its deadline, the kernel timer will allow the WDT to overflow.
 */
static int clock_division_ratio = WTCSR_CKS_4096;

#define next_ping_period(cks)	msecs_to_jiffies(cks - 4)

static unsigned long shwdt_is_open;
static struct watchdog_info sh_wdt_info;
static char shwdt_expect_close;
static struct timer_list timer;
static unsigned long next_heartbeat;

#define WATCHDOG_HEARTBEAT 30			/* 30 sec default heartbeat */
static int heartbeat = WATCHDOG_HEARTBEAT;	/* in seconds */

77
static int nowayout = WATCHDOG_NOWAYOUT;
L
Linus Torvalds 已提交
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

/**
 * 	sh_wdt_start - Start the Watchdog
 *
 * 	Starts the watchdog.
 */
static void sh_wdt_start(void)
{
	__u8 csr;

	next_heartbeat = jiffies + (heartbeat * HZ);
	mod_timer(&timer, next_ping_period(clock_division_ratio));

	csr = sh_wdt_read_csr();
	csr |= WTCSR_WT | clock_division_ratio;
	sh_wdt_write_csr(csr);

	sh_wdt_write_cnt(0);

	/*
	 * These processors have a bit of an inconsistent initialization
	 * process.. starting with SH-3, RSTS was moved to WTCSR, and the
	 * RSTCSR register was removed.
	 *
	 * On the SH-2 however, in addition with bits being in different
	 * locations, we must deal with RSTCSR outright..
	 */
	csr = sh_wdt_read_csr();
	csr |= WTCSR_TME;
	csr &= ~WTCSR_RSTS;
	sh_wdt_write_csr(csr);

#ifdef CONFIG_CPU_SH2
	/*
	 * Whoever came up with the RSTCSR semantics must've been smoking
	 * some of the good stuff, since in addition to the WTCSR/WTCNT write
	 * brain-damage, it's managed to fuck things up one step further..
	 *
	 * If we need to clear the WOVF bit, the upper byte has to be 0xa5..
	 * but if we want to touch RSTE or RSTS, the upper byte has to be
	 * 0x5a..
	 */
	csr = sh_wdt_read_rstcsr();
	csr &= ~RSTCSR_RSTS;
	sh_wdt_write_rstcsr(csr);
#endif
}

/**
 * 	sh_wdt_stop - Stop the Watchdog
 * 	Stops the watchdog.
 */
static void sh_wdt_stop(void)
{
	__u8 csr;

	del_timer(&timer);

	csr = sh_wdt_read_csr();
	csr &= ~WTCSR_TME;
	sh_wdt_write_csr(csr);
}

/**
 * 	sh_wdt_keepalive - Keep the Userspace Watchdog Alive
 * 	The Userspace watchdog got a KeepAlive: schedule the next heartbeat.
 */
P
Paul Mundt 已提交
145
static inline void sh_wdt_keepalive(void)
L
Linus Torvalds 已提交
146 147 148 149 150 151 152 153 154 155
{
	next_heartbeat = jiffies + (heartbeat * HZ);
}

/**
 * 	sh_wdt_set_heartbeat - Set the Userspace Watchdog heartbeat
 * 	Set the Userspace Watchdog heartbeat
 */
static int sh_wdt_set_heartbeat(int t)
{
P
Paul Mundt 已提交
156
	if (unlikely((t < 1) || (t > 3600))) /* arbitrary upper limit */
L
Linus Torvalds 已提交
157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180
		return -EINVAL;

	heartbeat = t;
	return 0;
}

/**
 * 	sh_wdt_ping - Ping the Watchdog
 *	@data: Unused
 *
 * 	Clears overflow bit, resets timer counter.
 */
static void sh_wdt_ping(unsigned long data)
{
	if (time_before(jiffies, next_heartbeat)) {
		__u8 csr;

		csr = sh_wdt_read_csr();
		csr &= ~WTCSR_IOVF;
		sh_wdt_write_csr(csr);

		sh_wdt_write_cnt(0);

		mod_timer(&timer, next_ping_period(clock_division_ratio));
P
Paul Mundt 已提交
181 182 183
	} else
		printk(KERN_WARNING PFX "Heartbeat lost! Will not ping "
		       "the watchdog\n");
L
Linus Torvalds 已提交
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
}

/**
 * 	sh_wdt_open - Open the Device
 * 	@inode: inode of device
 * 	@file: file handle of device
 *
 * 	Watchdog device is opened and started.
 */
static int sh_wdt_open(struct inode *inode, struct file *file)
{
	if (test_and_set_bit(0, &shwdt_is_open))
		return -EBUSY;
	if (nowayout)
		__module_get(THIS_MODULE);

	sh_wdt_start();

	return nonseekable_open(inode, file);
}

/**
 * 	sh_wdt_close - Close the Device
 * 	@inode: inode of device
 * 	@file: file handle of device
 *
 * 	Watchdog device is closed and stopped.
 */
static int sh_wdt_close(struct inode *inode, struct file *file)
{
	if (shwdt_expect_close == 42) {
		sh_wdt_stop();
	} else {
P
Paul Mundt 已提交
217 218
		printk(KERN_CRIT PFX "Unexpected close, not "
		       "stopping watchdog!\n");
L
Linus Torvalds 已提交
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
		sh_wdt_keepalive();
	}

	clear_bit(0, &shwdt_is_open);
	shwdt_expect_close = 0;

	return 0;
}

/**
 * 	sh_wdt_write - Write to Device
 * 	@file: file handle of device
 * 	@buf: buffer to write
 * 	@count: length of buffer
 * 	@ppos: offset
 *
 * 	Pings the watchdog on write.
 */
static ssize_t sh_wdt_write(struct file *file, const char *buf,
			    size_t count, loff_t *ppos)
{
	if (count) {
		if (!nowayout) {
			size_t i;

			shwdt_expect_close = 0;

			for (i = 0; i != count; i++) {
				char c;
				if (get_user(c, buf + i))
					return -EFAULT;
				if (c == 'V')
					shwdt_expect_close = 42;
			}
		}
		sh_wdt_keepalive();
	}

	return count;
}

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
/**
 * 	sh_wdt_mmap - map WDT/CPG registers into userspace
 * 	@file: file structure for the device
 * 	@vma: VMA to map the registers into
 *
 * 	A simple mmap() implementation for the corner cases where the counter
 * 	needs to be mapped in userspace directly. Due to the relatively small
 * 	size of the area, neighbouring registers not necessarily tied to the
 * 	CPG will also be accessible through the register page, so this remains
 * 	configurable for users that really know what they're doing.
 *
 *	Additionaly, the register page maps in the CPG register base relative
 *	to the nearest page-aligned boundary, which requires that userspace do
 *	the appropriate CPU subtype math for calculating the page offset for
 *	the counter value.
 */
static int sh_wdt_mmap(struct file *file, struct vm_area_struct *vma)
{
	int ret = -ENOSYS;

#ifdef CONFIG_SH_WDT_MMAP
	unsigned long addr;

	/* Only support the simple cases where we map in a register page. */
	if (((vma->vm_end - vma->vm_start) != PAGE_SIZE) || vma->vm_pgoff)
		return -EINVAL;

	/*
	 * Pick WTCNT as the start, it's usually the first register after the
	 * FRQCR, and neither one are generally page-aligned out of the box.
	 */
	addr = WTCNT & ~(PAGE_SIZE - 1);

	vma->vm_flags |= VM_IO;
	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);

	if (io_remap_pfn_range(vma, vma->vm_start, addr >> PAGE_SHIFT,
			       PAGE_SIZE, vma->vm_page_prot)) {
		printk(KERN_ERR PFX "%s: io_remap_pfn_range failed\n",
		       __FUNCTION__);
		return -EAGAIN;
	}

	ret = 0;
#endif

	return ret;
}

L
Linus Torvalds 已提交
309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380
/**
 * 	sh_wdt_ioctl - Query Device
 * 	@inode: inode of device
 * 	@file: file handle of device
 * 	@cmd: watchdog command
 * 	@arg: argument
 *
 * 	Query basic information from the device or ping it, as outlined by the
 * 	watchdog API.
 */
static int sh_wdt_ioctl(struct inode *inode, struct file *file,
			unsigned int cmd, unsigned long arg)
{
	int new_heartbeat;
	int options, retval = -EINVAL;

	switch (cmd) {
		case WDIOC_GETSUPPORT:
			return copy_to_user((struct watchdog_info *)arg,
					  &sh_wdt_info,
					  sizeof(sh_wdt_info)) ? -EFAULT : 0;
		case WDIOC_GETSTATUS:
		case WDIOC_GETBOOTSTATUS:
			return put_user(0, (int *)arg);
		case WDIOC_KEEPALIVE:
			sh_wdt_keepalive();
			return 0;
		case WDIOC_SETTIMEOUT:
			if (get_user(new_heartbeat, (int *)arg))
				return -EFAULT;

			if (sh_wdt_set_heartbeat(new_heartbeat))
				return -EINVAL;

			sh_wdt_keepalive();
			/* Fall */
		case WDIOC_GETTIMEOUT:
			return put_user(heartbeat, (int *)arg);
		case WDIOC_SETOPTIONS:
			if (get_user(options, (int *)arg))
				return -EFAULT;

			if (options & WDIOS_DISABLECARD) {
				sh_wdt_stop();
				retval = 0;
			}

			if (options & WDIOS_ENABLECARD) {
				sh_wdt_start();
				retval = 0;
			}

			return retval;
		default:
			return -ENOIOCTLCMD;
	}

	return 0;
}

/**
 * 	sh_wdt_notify_sys - Notifier Handler
 * 	@this: notifier block
 * 	@code: notifier event
 * 	@unused: unused
 *
 * 	Handles specific events, such as turning off the watchdog during a
 * 	shutdown event.
 */
static int sh_wdt_notify_sys(struct notifier_block *this,
			     unsigned long code, void *unused)
{
P
Paul Mundt 已提交
381
	if (code == SYS_DOWN || code == SYS_HALT)
L
Linus Torvalds 已提交
382 383 384 385 386
		sh_wdt_stop();

	return NOTIFY_DONE;
}

387
static const struct file_operations sh_wdt_fops = {
L
Linus Torvalds 已提交
388 389 390 391 392 393
	.owner		= THIS_MODULE,
	.llseek		= no_llseek,
	.write		= sh_wdt_write,
	.ioctl		= sh_wdt_ioctl,
	.open		= sh_wdt_open,
	.release	= sh_wdt_close,
394
	.mmap		= sh_wdt_mmap,
L
Linus Torvalds 已提交
395 396 397
};

static struct watchdog_info sh_wdt_info = {
P
Paul Mundt 已提交
398 399
	.options		= WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
				  WDIOF_MAGICCLOSE,
L
Linus Torvalds 已提交
400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424
	.firmware_version	= 1,
	.identity		= "SH WDT",
};

static struct notifier_block sh_wdt_notifier = {
	.notifier_call		= sh_wdt_notify_sys,
};

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

/**
 * 	sh_wdt_init - Initialize module
 * 	Registers the device and notifier handler. Actual device
 * 	initialization is handled by sh_wdt_open().
 */
static int __init sh_wdt_init(void)
{
	int rc;

	if ((clock_division_ratio < 0x5) || (clock_division_ratio > 0x7)) {
		clock_division_ratio = WTCSR_CKS_4096;
P
Paul Mundt 已提交
425 426
		printk(KERN_INFO PFX "clock_division_ratio value must "
		       "be 0x5<=x<=0x7, using %d\n", clock_division_ratio);
L
Linus Torvalds 已提交
427 428
	}

P
Paul Mundt 已提交
429 430
	rc = sh_wdt_set_heartbeat(heartbeat);
	if (unlikely(rc)) {
L
Linus Torvalds 已提交
431
		heartbeat = WATCHDOG_HEARTBEAT;
P
Paul Mundt 已提交
432 433
		printk(KERN_INFO PFX "heartbeat value must "
		       "be 1<=x<=3600, using %d\n", heartbeat);
L
Linus Torvalds 已提交
434 435 436 437 438 439 440
	}

	init_timer(&timer);
	timer.function = sh_wdt_ping;
	timer.data = 0;

	rc = register_reboot_notifier(&sh_wdt_notifier);
P
Paul Mundt 已提交
441 442 443
	if (unlikely(rc)) {
		printk(KERN_ERR PFX "Can't register reboot notifier (err=%d)\n",
		       rc);
L
Linus Torvalds 已提交
444 445 446 447
		return rc;
	}

	rc = misc_register(&sh_wdt_miscdev);
P
Paul Mundt 已提交
448 449 450
	if (unlikely(rc)) {
		printk(KERN_ERR PFX "Can't register miscdev on "
		       "minor=%d (err=%d)\n", sh_wdt_miscdev.minor, rc);
L
Linus Torvalds 已提交
451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477
		unregister_reboot_notifier(&sh_wdt_notifier);
		return rc;
	}

	printk(KERN_INFO PFX "initialized. heartbeat=%d sec (nowayout=%d)\n",
		heartbeat, nowayout);

	return 0;
}

/**
 * 	sh_wdt_exit - Deinitialize module
 * 	Unregisters the device and notifier handler. Actual device
 * 	deinitialization is handled by sh_wdt_close().
 */
static void __exit sh_wdt_exit(void)
{
	misc_deregister(&sh_wdt_miscdev);
	unregister_reboot_notifier(&sh_wdt_notifier);
}

MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
MODULE_DESCRIPTION("SuperH watchdog driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);

module_param(clock_division_ratio, int, 0);
P
Paul Mundt 已提交
478
MODULE_PARM_DESC(clock_division_ratio, "Clock division ratio. Valid ranges are from 0x5 (1.31ms) to 0x7 (5.25ms). (default=" __MODULE_STRING(clock_division_ratio) ")");
L
Linus Torvalds 已提交
479 480 481 482 483

module_param(heartbeat, int, 0);
MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds. (1<=heartbeat<=3600, default=" __MODULE_STRING(WATCHDOG_HEARTBEAT) ")");

module_param(nowayout, int, 0);
P
Paul Mundt 已提交
484
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
L
Linus Torvalds 已提交
485 486 487

module_init(sh_wdt_init);
module_exit(sh_wdt_exit);