blob: dc403629aeb3d79a4e112798fe4ababfd2751070 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * drivers/char/watchdog/shwdt.c
3 *
4 * Watchdog driver for integrated watchdog in the SuperH processors.
5 *
6 * Copyright (C) 2001, 2002, 2003 Paul Mundt <lethal@linux-sh.org>
7 *
8 * This program is free software; you can redistribute it and/or modify it
9 * under the terms of the GNU General Public License as published by the
10 * Free Software Foundation; either version 2 of the License, or (at your
11 * option) any later version.
12 *
13 * 14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
14 * Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
15 *
16 * 19-Apr-2002 Rob Radez <rob@osinvestor.com>
17 * Added expect close support, made emulated timeout runtime changeable
18 * general cleanups, add some ioctls
19 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070020#include <linux/module.h>
21#include <linux/moduleparam.h>
22#include <linux/init.h>
23#include <linux/types.h>
24#include <linux/miscdevice.h>
25#include <linux/watchdog.h>
26#include <linux/reboot.h>
27#include <linux/notifier.h>
28#include <linux/ioport.h>
29#include <linux/fs.h>
Paul Mundtf1184202006-09-27 17:53:59 +090030#include <linux/mm.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070031#include <asm/io.h>
32#include <asm/uaccess.h>
33#include <asm/watchdog.h>
34
35#define PFX "shwdt: "
36
37/*
38 * Default clock division ratio is 5.25 msecs. For an additional table of
39 * values, consult the asm-sh/watchdog.h. Overload this at module load
40 * time.
41 *
42 * In order for this to work reliably we need to have HZ set to 1000 or
43 * something quite higher than 100 (or we need a proper high-res timer
44 * implementation that will deal with this properly), otherwise the 10ms
45 * resolution of a jiffy is enough to trigger the overflow. For things like
46 * the SH-4 and SH-5, this isn't necessarily that big of a problem, though
47 * for the SH-2 and SH-3, this isn't recommended unless the WDT is absolutely
48 * necssary.
49 *
50 * As a result of this timing problem, the only modes that are particularly
51 * feasible are the 4096 and the 2048 divisors, which yeild 5.25 and 2.62ms
52 * overflow periods respectively.
53 *
54 * Also, since we can't really expect userspace to be responsive enough
55 * before the overflow happens, we maintain two seperate timers .. One in
56 * the kernel for clearing out WOVF every 2ms or so (again, this depends on
57 * HZ == 1000), and another for monitoring userspace writes to the WDT device.
58 *
59 * As such, we currently use a configurable heartbeat interval which defaults
60 * to 30s. In this case, the userspace daemon is only responsible for periodic
61 * writes to the device before the next heartbeat is scheduled. If the daemon
62 * misses its deadline, the kernel timer will allow the WDT to overflow.
63 */
64static int clock_division_ratio = WTCSR_CKS_4096;
65
66#define next_ping_period(cks) msecs_to_jiffies(cks - 4)
67
68static unsigned long shwdt_is_open;
69static struct watchdog_info sh_wdt_info;
70static char shwdt_expect_close;
71static struct timer_list timer;
72static unsigned long next_heartbeat;
73
74#define WATCHDOG_HEARTBEAT 30 /* 30 sec default heartbeat */
75static int heartbeat = WATCHDOG_HEARTBEAT; /* in seconds */
76
Andrey Panin4bfdf372005-07-27 11:43:58 -070077static int nowayout = WATCHDOG_NOWAYOUT;
Linus Torvalds1da177e2005-04-16 15:20:36 -070078
79/**
80 * sh_wdt_start - Start the Watchdog
81 *
82 * Starts the watchdog.
83 */
84static void sh_wdt_start(void)
85{
86 __u8 csr;
87
88 next_heartbeat = jiffies + (heartbeat * HZ);
89 mod_timer(&timer, next_ping_period(clock_division_ratio));
90
91 csr = sh_wdt_read_csr();
92 csr |= WTCSR_WT | clock_division_ratio;
93 sh_wdt_write_csr(csr);
94
95 sh_wdt_write_cnt(0);
96
97 /*
98 * These processors have a bit of an inconsistent initialization
99 * process.. starting with SH-3, RSTS was moved to WTCSR, and the
100 * RSTCSR register was removed.
101 *
102 * On the SH-2 however, in addition with bits being in different
103 * locations, we must deal with RSTCSR outright..
104 */
105 csr = sh_wdt_read_csr();
106 csr |= WTCSR_TME;
107 csr &= ~WTCSR_RSTS;
108 sh_wdt_write_csr(csr);
109
110#ifdef CONFIG_CPU_SH2
111 /*
112 * Whoever came up with the RSTCSR semantics must've been smoking
113 * some of the good stuff, since in addition to the WTCSR/WTCNT write
114 * brain-damage, it's managed to fuck things up one step further..
115 *
116 * If we need to clear the WOVF bit, the upper byte has to be 0xa5..
117 * but if we want to touch RSTE or RSTS, the upper byte has to be
118 * 0x5a..
119 */
120 csr = sh_wdt_read_rstcsr();
121 csr &= ~RSTCSR_RSTS;
122 sh_wdt_write_rstcsr(csr);
123#endif
124}
125
126/**
127 * sh_wdt_stop - Stop the Watchdog
Linus Torvalds1da177e2005-04-16 15:20:36 -0700128 * Stops the watchdog.
129 */
130static void sh_wdt_stop(void)
131{
132 __u8 csr;
133
134 del_timer(&timer);
135
136 csr = sh_wdt_read_csr();
137 csr &= ~WTCSR_TME;
138 sh_wdt_write_csr(csr);
139}
140
141/**
142 * sh_wdt_keepalive - Keep the Userspace Watchdog Alive
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143 * The Userspace watchdog got a KeepAlive: schedule the next heartbeat.
144 */
Paul Mundte4c2cfe2006-09-27 12:31:01 +0900145static inline void sh_wdt_keepalive(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700146{
147 next_heartbeat = jiffies + (heartbeat * HZ);
148}
149
150/**
151 * sh_wdt_set_heartbeat - Set the Userspace Watchdog heartbeat
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152 * Set the Userspace Watchdog heartbeat
153 */
154static int sh_wdt_set_heartbeat(int t)
155{
Paul Mundte4c2cfe2006-09-27 12:31:01 +0900156 if (unlikely((t < 1) || (t > 3600))) /* arbitrary upper limit */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700157 return -EINVAL;
158
159 heartbeat = t;
160 return 0;
161}
162
163/**
164 * sh_wdt_ping - Ping the Watchdog
Linus Torvalds1da177e2005-04-16 15:20:36 -0700165 * @data: Unused
166 *
167 * Clears overflow bit, resets timer counter.
168 */
169static void sh_wdt_ping(unsigned long data)
170{
171 if (time_before(jiffies, next_heartbeat)) {
172 __u8 csr;
173
174 csr = sh_wdt_read_csr();
175 csr &= ~WTCSR_IOVF;
176 sh_wdt_write_csr(csr);
177
178 sh_wdt_write_cnt(0);
179
180 mod_timer(&timer, next_ping_period(clock_division_ratio));
Paul Mundte4c2cfe2006-09-27 12:31:01 +0900181 } else
182 printk(KERN_WARNING PFX "Heartbeat lost! Will not ping "
183 "the watchdog\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700184}
185
186/**
187 * sh_wdt_open - Open the Device
Linus Torvalds1da177e2005-04-16 15:20:36 -0700188 * @inode: inode of device
189 * @file: file handle of device
190 *
191 * Watchdog device is opened and started.
192 */
193static int sh_wdt_open(struct inode *inode, struct file *file)
194{
195 if (test_and_set_bit(0, &shwdt_is_open))
196 return -EBUSY;
197 if (nowayout)
198 __module_get(THIS_MODULE);
199
200 sh_wdt_start();
201
202 return nonseekable_open(inode, file);
203}
204
205/**
206 * sh_wdt_close - Close the Device
Linus Torvalds1da177e2005-04-16 15:20:36 -0700207 * @inode: inode of device
208 * @file: file handle of device
209 *
210 * Watchdog device is closed and stopped.
211 */
212static int sh_wdt_close(struct inode *inode, struct file *file)
213{
214 if (shwdt_expect_close == 42) {
215 sh_wdt_stop();
216 } else {
Paul Mundte4c2cfe2006-09-27 12:31:01 +0900217 printk(KERN_CRIT PFX "Unexpected close, not "
218 "stopping watchdog!\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700219 sh_wdt_keepalive();
220 }
221
222 clear_bit(0, &shwdt_is_open);
223 shwdt_expect_close = 0;
224
225 return 0;
226}
227
228/**
229 * sh_wdt_write - Write to Device
Linus Torvalds1da177e2005-04-16 15:20:36 -0700230 * @file: file handle of device
231 * @buf: buffer to write
232 * @count: length of buffer
233 * @ppos: offset
234 *
235 * Pings the watchdog on write.
236 */
237static ssize_t sh_wdt_write(struct file *file, const char *buf,
238 size_t count, loff_t *ppos)
239{
240 if (count) {
241 if (!nowayout) {
242 size_t i;
243
244 shwdt_expect_close = 0;
245
246 for (i = 0; i != count; i++) {
247 char c;
248 if (get_user(c, buf + i))
249 return -EFAULT;
250 if (c == 'V')
251 shwdt_expect_close = 42;
252 }
253 }
254 sh_wdt_keepalive();
255 }
256
257 return count;
258}
259
260/**
Paul Mundtf1184202006-09-27 17:53:59 +0900261 * sh_wdt_mmap - map WDT/CPG registers into userspace
262 * @file: file structure for the device
263 * @vma: VMA to map the registers into
264 *
265 * A simple mmap() implementation for the corner cases where the counter
266 * needs to be mapped in userspace directly. Due to the relatively small
267 * size of the area, neighbouring registers not necessarily tied to the
268 * CPG will also be accessible through the register page, so this remains
269 * configurable for users that really know what they're doing.
270 *
271 * Additionaly, the register page maps in the CPG register base relative
272 * to the nearest page-aligned boundary, which requires that userspace do
273 * the appropriate CPU subtype math for calculating the page offset for
274 * the counter value.
275 */
276static int sh_wdt_mmap(struct file *file, struct vm_area_struct *vma)
277{
278 int ret = -ENOSYS;
279
280#ifdef CONFIG_SH_WDT_MMAP
281 unsigned long addr;
282
283 /* Only support the simple cases where we map in a register page. */
284 if (((vma->vm_end - vma->vm_start) != PAGE_SIZE) || vma->vm_pgoff)
285 return -EINVAL;
286
287 /*
288 * Pick WTCNT as the start, it's usually the first register after the
289 * FRQCR, and neither one are generally page-aligned out of the box.
290 */
291 addr = WTCNT & ~(PAGE_SIZE - 1);
292
293 vma->vm_flags |= VM_IO;
294 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
295
296 if (io_remap_pfn_range(vma, vma->vm_start, addr >> PAGE_SHIFT,
297 PAGE_SIZE, vma->vm_page_prot)) {
298 printk(KERN_ERR PFX "%s: io_remap_pfn_range failed\n",
299 __FUNCTION__);
300 return -EAGAIN;
301 }
302
303 ret = 0;
304#endif
305
306 return ret;
307}
308
309/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700310 * sh_wdt_ioctl - Query Device
Linus Torvalds1da177e2005-04-16 15:20:36 -0700311 * @inode: inode of device
312 * @file: file handle of device
313 * @cmd: watchdog command
314 * @arg: argument
315 *
316 * Query basic information from the device or ping it, as outlined by the
317 * watchdog API.
318 */
319static int sh_wdt_ioctl(struct inode *inode, struct file *file,
320 unsigned int cmd, unsigned long arg)
321{
322 int new_heartbeat;
323 int options, retval = -EINVAL;
324
325 switch (cmd) {
326 case WDIOC_GETSUPPORT:
327 return copy_to_user((struct watchdog_info *)arg,
328 &sh_wdt_info,
329 sizeof(sh_wdt_info)) ? -EFAULT : 0;
330 case WDIOC_GETSTATUS:
331 case WDIOC_GETBOOTSTATUS:
332 return put_user(0, (int *)arg);
333 case WDIOC_KEEPALIVE:
334 sh_wdt_keepalive();
335 return 0;
336 case WDIOC_SETTIMEOUT:
337 if (get_user(new_heartbeat, (int *)arg))
338 return -EFAULT;
339
340 if (sh_wdt_set_heartbeat(new_heartbeat))
341 return -EINVAL;
342
343 sh_wdt_keepalive();
344 /* Fall */
345 case WDIOC_GETTIMEOUT:
346 return put_user(heartbeat, (int *)arg);
347 case WDIOC_SETOPTIONS:
348 if (get_user(options, (int *)arg))
349 return -EFAULT;
350
351 if (options & WDIOS_DISABLECARD) {
352 sh_wdt_stop();
353 retval = 0;
354 }
355
356 if (options & WDIOS_ENABLECARD) {
357 sh_wdt_start();
358 retval = 0;
359 }
360
361 return retval;
362 default:
Samuel Tardieu795b89d2006-09-09 17:34:31 +0200363 return -ENOTTY;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700364 }
365
366 return 0;
367}
368
369/**
370 * sh_wdt_notify_sys - Notifier Handler
Linus Torvalds1da177e2005-04-16 15:20:36 -0700371 * @this: notifier block
372 * @code: notifier event
373 * @unused: unused
374 *
375 * Handles specific events, such as turning off the watchdog during a
376 * shutdown event.
377 */
378static int sh_wdt_notify_sys(struct notifier_block *this,
379 unsigned long code, void *unused)
380{
Paul Mundte4c2cfe2006-09-27 12:31:01 +0900381 if (code == SYS_DOWN || code == SYS_HALT)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700382 sh_wdt_stop();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700383
384 return NOTIFY_DONE;
385}
386
Arjan van de Ven62322d22006-07-03 00:24:21 -0700387static const struct file_operations sh_wdt_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700388 .owner = THIS_MODULE,
389 .llseek = no_llseek,
390 .write = sh_wdt_write,
391 .ioctl = sh_wdt_ioctl,
392 .open = sh_wdt_open,
393 .release = sh_wdt_close,
Paul Mundtf1184202006-09-27 17:53:59 +0900394 .mmap = sh_wdt_mmap,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700395};
396
397static struct watchdog_info sh_wdt_info = {
Paul Mundte4c2cfe2006-09-27 12:31:01 +0900398 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
399 WDIOF_MAGICCLOSE,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700400 .firmware_version = 1,
401 .identity = "SH WDT",
402};
403
404static struct notifier_block sh_wdt_notifier = {
405 .notifier_call = sh_wdt_notify_sys,
406};
407
408static struct miscdevice sh_wdt_miscdev = {
409 .minor = WATCHDOG_MINOR,
410 .name = "watchdog",
411 .fops = &sh_wdt_fops,
412};
413
414/**
415 * sh_wdt_init - Initialize module
Linus Torvalds1da177e2005-04-16 15:20:36 -0700416 * Registers the device and notifier handler. Actual device
417 * initialization is handled by sh_wdt_open().
418 */
419static int __init sh_wdt_init(void)
420{
421 int rc;
422
423 if ((clock_division_ratio < 0x5) || (clock_division_ratio > 0x7)) {
424 clock_division_ratio = WTCSR_CKS_4096;
Paul Mundte4c2cfe2006-09-27 12:31:01 +0900425 printk(KERN_INFO PFX "clock_division_ratio value must "
426 "be 0x5<=x<=0x7, using %d\n", clock_division_ratio);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700427 }
428
Paul Mundte4c2cfe2006-09-27 12:31:01 +0900429 rc = sh_wdt_set_heartbeat(heartbeat);
430 if (unlikely(rc)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700431 heartbeat = WATCHDOG_HEARTBEAT;
Paul Mundte4c2cfe2006-09-27 12:31:01 +0900432 printk(KERN_INFO PFX "heartbeat value must "
433 "be 1<=x<=3600, using %d\n", heartbeat);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700434 }
435
436 init_timer(&timer);
437 timer.function = sh_wdt_ping;
438 timer.data = 0;
439
440 rc = register_reboot_notifier(&sh_wdt_notifier);
Paul Mundte4c2cfe2006-09-27 12:31:01 +0900441 if (unlikely(rc)) {
442 printk(KERN_ERR PFX "Can't register reboot notifier (err=%d)\n",
443 rc);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700444 return rc;
445 }
446
447 rc = misc_register(&sh_wdt_miscdev);
Paul Mundte4c2cfe2006-09-27 12:31:01 +0900448 if (unlikely(rc)) {
449 printk(KERN_ERR PFX "Can't register miscdev on "
450 "minor=%d (err=%d)\n", sh_wdt_miscdev.minor, rc);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700451 unregister_reboot_notifier(&sh_wdt_notifier);
452 return rc;
453 }
454
455 printk(KERN_INFO PFX "initialized. heartbeat=%d sec (nowayout=%d)\n",
456 heartbeat, nowayout);
457
458 return 0;
459}
460
461/**
462 * sh_wdt_exit - Deinitialize module
Linus Torvalds1da177e2005-04-16 15:20:36 -0700463 * Unregisters the device and notifier handler. Actual device
464 * deinitialization is handled by sh_wdt_close().
465 */
466static void __exit sh_wdt_exit(void)
467{
468 misc_deregister(&sh_wdt_miscdev);
469 unregister_reboot_notifier(&sh_wdt_notifier);
470}
471
472MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
473MODULE_DESCRIPTION("SuperH watchdog driver");
474MODULE_LICENSE("GPL");
475MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
476
477module_param(clock_division_ratio, int, 0);
Paul Mundte4c2cfe2006-09-27 12:31:01 +0900478MODULE_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) ")");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700479
480module_param(heartbeat, int, 0);
481MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds. (1<=heartbeat<=3600, default=" __MODULE_STRING(WATCHDOG_HEARTBEAT) ")");
482
483module_param(nowayout, int, 0);
Paul Mundte4c2cfe2006-09-27 12:31:01 +0900484MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700485
486module_init(sh_wdt_init);
487module_exit(sh_wdt_exit);