1 /*
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 */
20 #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>
30 #include <linux/mm.h>
31 #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 separate 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 */
64 static int clock_division_ratio = WTCSR_CKS_4096;
65
66 #define next_ping_period(cks) msecs_to_jiffies(cks - 4)
67
68 static void sh_wdt_ping(unsigned long data);
69
70 static unsigned long shwdt_is_open;
71 static struct watchdog_info sh_wdt_info;
72 static char shwdt_expect_close;
73 static DEFINE_TIMER(timer, sh_wdt_ping, 0, 0);
74 static unsigned long next_heartbeat;
75
76 #define WATCHDOG_HEARTBEAT 30 /* 30 sec default heartbeat */
77 static int heartbeat = WATCHDOG_HEARTBEAT; /* in seconds */
78
79 static int nowayout = WATCHDOG_NOWAYOUT;
80
81 /**
82 * sh_wdt_start - Start the Watchdog
83 *
84 * Starts the watchdog.
85 */
86 static void sh_wdt_start(void)
87 {
88 __u8 csr;
89
90 next_heartbeat = jiffies + (heartbeat * HZ);
91 mod_timer(&timer, next_ping_period(clock_division_ratio));
92
93 csr = sh_wdt_read_csr();
94 csr |= WTCSR_WT | clock_division_ratio;
95 sh_wdt_write_csr(csr);
96
97 sh_wdt_write_cnt(0);
98
99 /*
100 * These processors have a bit of an inconsistent initialization
101 * process.. starting with SH-3, RSTS was moved to WTCSR, and the
102 * RSTCSR register was removed.
103 *
104 * On the SH-2 however, in addition with bits being in different
105 * locations, we must deal with RSTCSR outright..
106 */
107 csr = sh_wdt_read_csr();
108 csr |= WTCSR_TME;
109 csr &= ~WTCSR_RSTS;
110 sh_wdt_write_csr(csr);
111
112 #ifdef CONFIG_CPU_SH2
113 /*
114 * Whoever came up with the RSTCSR semantics must've been smoking
115 * some of the good stuff, since in addition to the WTCSR/WTCNT write
116 * brain-damage, it's managed to fuck things up one step further..
117 *
118 * If we need to clear the WOVF bit, the upper byte has to be 0xa5..
119 * but if we want to touch RSTE or RSTS, the upper byte has to be
120 * 0x5a..
121 */
122 csr = sh_wdt_read_rstcsr();
123 csr &= ~RSTCSR_RSTS;
124 sh_wdt_write_rstcsr(csr);
125 #endif
126 }
127
128 /**
129 * sh_wdt_stop - Stop the Watchdog
130 * Stops the watchdog.
131 */
132 static void sh_wdt_stop(void)
133 {
134 __u8 csr;
135
136 del_timer(&timer);
137
138 csr = sh_wdt_read_csr();
139 csr &= ~WTCSR_TME;
140 sh_wdt_write_csr(csr);
141 }
142
143 /**
144 * sh_wdt_keepalive - Keep the Userspace Watchdog Alive
145 * The Userspace watchdog got a KeepAlive: schedule the next heartbeat.
146 */
147 static inline void sh_wdt_keepalive(void)
148 {
149 next_heartbeat = jiffies + (heartbeat * HZ);
150 }
151
152 /**
153 * sh_wdt_set_heartbeat - Set the Userspace Watchdog heartbeat
154 * Set the Userspace Watchdog heartbeat
155 */
156 static int sh_wdt_set_heartbeat(int t)
157 {
158 if (unlikely((t < 1) || (t > 3600))) /* arbitrary upper limit */
159 return -EINVAL;
160
161 heartbeat = t;
162 return 0;
163 }
164
165 /**
166 * sh_wdt_ping - Ping the Watchdog
167 * @data: Unused
168 *
169 * Clears overflow bit, resets timer counter.
170 */
171 static void sh_wdt_ping(unsigned long data)
172 {
173 if (time_before(jiffies, next_heartbeat)) {
174 __u8 csr;
175
176 csr = sh_wdt_read_csr();
177 csr &= ~WTCSR_IOVF;
178 sh_wdt_write_csr(csr);
179
180 sh_wdt_write_cnt(0);
181
182 mod_timer(&timer, next_ping_period(clock_division_ratio));
183 } else
184 printk(KERN_WARNING PFX "Heartbeat lost! Will not ping "
185 "the watchdog\n");
186 }
187
188 /**
189 * sh_wdt_open - Open the Device
190 * @inode: inode of device
191 * @file: file handle of device
192 *
193 * Watchdog device is opened and started.
194 */
195 static int sh_wdt_open(struct inode *inode, struct file *file)
196 {
197 if (test_and_set_bit(0, &shwdt_is_open))
198 return -EBUSY;
199 if (nowayout)
200 __module_get(THIS_MODULE);
201
202 sh_wdt_start();
203
204 return nonseekable_open(inode, file);
205 }
206
207 /**
208 * sh_wdt_close - Close the Device
209 * @inode: inode of device
210 * @file: file handle of device
211 *
212 * Watchdog device is closed and stopped.
213 */
214 static int sh_wdt_close(struct inode *inode, struct file *file)
215 {
216 if (shwdt_expect_close == 42) {
217 sh_wdt_stop();
218 } else {
219 printk(KERN_CRIT PFX "Unexpected close, not "
220 "stopping watchdog!\n");
221 sh_wdt_keepalive();
222 }
223
224 clear_bit(0, &shwdt_is_open);
225 shwdt_expect_close = 0;
226
227 return 0;
228 }
229
230 /**
231 * sh_wdt_write - Write to Device
232 * @file: file handle of device
233 * @buf: buffer to write
234 * @count: length of buffer
235 * @ppos: offset
236 *
237 * Pings the watchdog on write.
238 */
239 static ssize_t sh_wdt_write(struct file *file, const char *buf,
240 size_t count, loff_t *ppos)
241 {
242 if (count) {
243 if (!nowayout) {
244 size_t i;
245
246 shwdt_expect_close = 0;
247
248 for (i = 0; i != count; i++) {
249 char c;
250 if (get_user(c, buf + i))
251 return -EFAULT;
252 if (c == 'V')
253 shwdt_expect_close = 42;
254 }
255 }
256 sh_wdt_keepalive();
257 }
258
259 return count;
260 }
261
262 /**
263 * sh_wdt_mmap - map WDT/CPG registers into userspace
264 * @file: file structure for the device
265 * @vma: VMA to map the registers into
266 *
267 * A simple mmap() implementation for the corner cases where the counter
268 * needs to be mapped in userspace directly. Due to the relatively small
269 * size of the area, neighbouring registers not necessarily tied to the
270 * CPG will also be accessible through the register page, so this remains
271 * configurable for users that really know what they're doing.
272 *
273 * Additionaly, the register page maps in the CPG register base relative
274 * to the nearest page-aligned boundary, which requires that userspace do
275 * the appropriate CPU subtype math for calculating the page offset for
276 * the counter value.
277 */
278 static int sh_wdt_mmap(struct file *file, struct vm_area_struct *vma)
279 {
280 int ret = -ENOSYS;
281
282 #ifdef CONFIG_SH_WDT_MMAP
283 unsigned long addr;
284
285 /* Only support the simple cases where we map in a register page. */
286 if (((vma->vm_end - vma->vm_start) != PAGE_SIZE) || vma->vm_pgoff)
287 return -EINVAL;
288
289 /*
290 * Pick WTCNT as the start, it's usually the first register after the
291 * FRQCR, and neither one are generally page-aligned out of the box.
292 */
293 addr = WTCNT & ~(PAGE_SIZE - 1);
294
295 vma->vm_flags |= VM_IO;
296 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
297
298 if (io_remap_pfn_range(vma, vma->vm_start, addr >> PAGE_SHIFT,
299 PAGE_SIZE, vma->vm_page_prot)) {
300 printk(KERN_ERR PFX "%s: io_remap_pfn_range failed\n",
301 __func__);
302 return -EAGAIN;
303 }
304
305 ret = 0;
306 #endif
307
308 return ret;
309 }
310
311 /**
312 * sh_wdt_ioctl - Query Device
313 * @inode: inode of device
314 * @file: file handle of device
315 * @cmd: watchdog command
316 * @arg: argument
317 *
318 * Query basic information from the device or ping it, as outlined by the
319 * watchdog API.
320 */
321 static int sh_wdt_ioctl(struct inode *inode, struct file *file,
322 unsigned int cmd, unsigned long arg)
323 {
324 int new_heartbeat;
325 int options, retval = -EINVAL;
326
327 switch (cmd) {
328 case WDIOC_GETSUPPORT:
329 return copy_to_user((struct watchdog_info *)arg,
330 &sh_wdt_info,
331 sizeof(sh_wdt_info)) ? -EFAULT : 0;
332 case WDIOC_GETSTATUS:
333 case WDIOC_GETBOOTSTATUS:
334 return put_user(0, (int *)arg);
335 case WDIOC_KEEPALIVE:
336 sh_wdt_keepalive();
337 return 0;
338 case WDIOC_SETTIMEOUT:
339 if (get_user(new_heartbeat, (int *)arg))
340 return -EFAULT;
341
342 if (sh_wdt_set_heartbeat(new_heartbeat))
343 return -EINVAL;
344
345 sh_wdt_keepalive();
346 /* Fall */
347 case WDIOC_GETTIMEOUT:
348 return put_user(heartbeat, (int *)arg);
349 case WDIOC_SETOPTIONS:
350 if (get_user(options, (int *)arg))
351 return -EFAULT;
352
353 if (options & WDIOS_DISABLECARD) {
354 sh_wdt_stop();
355 retval = 0;
356 }
357
358 if (options & WDIOS_ENABLECARD) {
359 sh_wdt_start();
360 retval = 0;
361 }
362
363 return retval;
364 default:
365 return -ENOTTY;
366 }
367
368 return 0;
369 }
370
371 /**
372 * sh_wdt_notify_sys - Notifier Handler
373 * @this: notifier block
374 * @code: notifier event
375 * @unused: unused
376 *
377 * Handles specific events, such as turning off the watchdog during a
378 * shutdown event.
379 */
380 static int sh_wdt_notify_sys(struct notifier_block *this,
381 unsigned long code, void *unused)
382 {
383 if (code == SYS_DOWN || code == SYS_HALT)
384 sh_wdt_stop();
385
386 return NOTIFY_DONE;
387 }
388
389 static const struct file_operations sh_wdt_fops = {
390 .owner = THIS_MODULE,
391 .llseek = no_llseek,
392 .write = sh_wdt_write,
393 .ioctl = sh_wdt_ioctl,
394 .open = sh_wdt_open,
395 .release = sh_wdt_close,
396 .mmap = sh_wdt_mmap,
397 };
398
399 static struct watchdog_info sh_wdt_info = {
400 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
401 WDIOF_MAGICCLOSE,
402 .firmware_version = 1,
403 .identity = "SH WDT",
404 };
405
406 static struct notifier_block sh_wdt_notifier = {
407 .notifier_call = sh_wdt_notify_sys,
408 };
409
410 static struct miscdevice sh_wdt_miscdev = {
411 .minor = WATCHDOG_MINOR,
412 .name = "watchdog",
413 .fops = &sh_wdt_fops,
414 };
415
416 /**
417 * sh_wdt_init - Initialize module
418 * Registers the device and notifier handler. Actual device
419 * initialization is handled by sh_wdt_open().
420 */
421 static int __init sh_wdt_init(void)
422 {
423 int rc;
424
425 if ((clock_division_ratio < 0x5) || (clock_division_ratio > 0x7)) {
426 clock_division_ratio = WTCSR_CKS_4096;
427 printk(KERN_INFO PFX "clock_division_ratio value must "
428 "be 0x5<=x<=0x7, using %d\n", clock_division_ratio);
429 }
430
431 rc = sh_wdt_set_heartbeat(heartbeat);
432 if (unlikely(rc)) {
433 heartbeat = WATCHDOG_HEARTBEAT;
434 printk(KERN_INFO PFX "heartbeat value must "
435 "be 1<=x<=3600, using %d\n", heartbeat);
436 }
437
438 rc = register_reboot_notifier(&sh_wdt_notifier);
439 if (unlikely(rc)) {
440 printk(KERN_ERR PFX "Can't register reboot notifier (err=%d)\n",
441 rc);
442 return rc;
443 }
444
445 rc = misc_register(&sh_wdt_miscdev);
446 if (unlikely(rc)) {
447 printk(KERN_ERR PFX "Can't register miscdev on "
448 "minor=%d (err=%d)\n", sh_wdt_miscdev.minor, rc);
449 unregister_reboot_notifier(&sh_wdt_notifier);
450 return rc;
451 }
452
453 printk(KERN_INFO PFX "initialized. heartbeat=%d sec (nowayout=%d)\n",
454 heartbeat, nowayout);
455
456 return 0;
457 }
458
459 /**
460 * sh_wdt_exit - Deinitialize module
461 * Unregisters the device and notifier handler. Actual device
462 * deinitialization is handled by sh_wdt_close().
463 */
464 static void __exit sh_wdt_exit(void)
465 {
466 misc_deregister(&sh_wdt_miscdev);
467 unregister_reboot_notifier(&sh_wdt_notifier);
468 }
469
470 MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
471 MODULE_DESCRIPTION("SuperH watchdog driver");
472 MODULE_LICENSE("GPL");
473 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
474
475 module_param(clock_division_ratio, int, 0);
476 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) ")");
477
478 module_param(heartbeat, int, 0);
479 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds. (1<=heartbeat<=3600, default=" __MODULE_STRING(WATCHDOG_HEARTBEAT) ")");
480
481 module_param(nowayout, int, 0);
482 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
483
484 module_init(sh_wdt_init);
485 module_exit(sh_wdt_exit);
486
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