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Linux/drivers/watchdog/bfin_wdt.c

  1 /*
  2  * Blackfin On-Chip Watchdog Driver
  3  *
  4  * Originally based on softdog.c
  5  * Copyright 2006-2010 Analog Devices Inc.
  6  * Copyright 2006-2007 Michele d'Amico
  7  * Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>
  8  *
  9  * Enter bugs at http://blackfin.uclinux.org/
 10  *
 11  * Licensed under the GPL-2 or later.
 12  */
 13 
 14 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 15 
 16 #include <linux/platform_device.h>
 17 #include <linux/module.h>
 18 #include <linux/moduleparam.h>
 19 #include <linux/types.h>
 20 #include <linux/timer.h>
 21 #include <linux/miscdevice.h>
 22 #include <linux/watchdog.h>
 23 #include <linux/fs.h>
 24 #include <linux/init.h>
 25 #include <linux/interrupt.h>
 26 #include <linux/uaccess.h>
 27 #include <asm/blackfin.h>
 28 #include <asm/bfin_watchdog.h>
 29 
 30 #define stamp(fmt, args...) \
 31         pr_debug("%s:%i: " fmt "\n", __func__, __LINE__, ## args)
 32 #define stampit() stamp("here i am")
 33 
 34 #define WATCHDOG_NAME "bfin-wdt"
 35 
 36 /* The BF561 has two watchdogs (one per core), but since Linux
 37  * only runs on core A, we'll just work with that one.
 38  */
 39 #ifdef BF561_FAMILY
 40 # define bfin_read_WDOG_CTL()    bfin_read_WDOGA_CTL()
 41 # define bfin_read_WDOG_CNT()    bfin_read_WDOGA_CNT()
 42 # define bfin_read_WDOG_STAT()   bfin_read_WDOGA_STAT()
 43 # define bfin_write_WDOG_CTL(x)  bfin_write_WDOGA_CTL(x)
 44 # define bfin_write_WDOG_CNT(x)  bfin_write_WDOGA_CNT(x)
 45 # define bfin_write_WDOG_STAT(x) bfin_write_WDOGA_STAT(x)
 46 #endif
 47 
 48 /* some defaults */
 49 #define WATCHDOG_TIMEOUT 20
 50 
 51 static unsigned int timeout = WATCHDOG_TIMEOUT;
 52 static bool nowayout = WATCHDOG_NOWAYOUT;
 53 static const struct watchdog_info bfin_wdt_info;
 54 static unsigned long open_check;
 55 static char expect_close;
 56 static DEFINE_SPINLOCK(bfin_wdt_spinlock);
 57 
 58 /**
 59  *      bfin_wdt_keepalive - Keep the Userspace Watchdog Alive
 60  *
 61  *      The Userspace watchdog got a KeepAlive: schedule the next timeout.
 62  */
 63 static int bfin_wdt_keepalive(void)
 64 {
 65         stampit();
 66         bfin_write_WDOG_STAT(0);
 67         return 0;
 68 }
 69 
 70 /**
 71  *      bfin_wdt_stop - Stop the Watchdog
 72  *
 73  *      Stops the on-chip watchdog.
 74  */
 75 static int bfin_wdt_stop(void)
 76 {
 77         stampit();
 78         bfin_write_WDOG_CTL(WDEN_DISABLE);
 79         return 0;
 80 }
 81 
 82 /**
 83  *      bfin_wdt_start - Start the Watchdog
 84  *
 85  *      Starts the on-chip watchdog.  Automatically loads WDOG_CNT
 86  *      into WDOG_STAT for us.
 87  */
 88 static int bfin_wdt_start(void)
 89 {
 90         stampit();
 91         bfin_write_WDOG_CTL(WDEN_ENABLE | ICTL_RESET);
 92         return 0;
 93 }
 94 
 95 /**
 96  *      bfin_wdt_running - Check Watchdog status
 97  *
 98  *      See if the watchdog is running.
 99  */
100 static int bfin_wdt_running(void)
101 {
102         stampit();
103         return ((bfin_read_WDOG_CTL() & WDEN_MASK) != WDEN_DISABLE);
104 }
105 
106 /**
107  *      bfin_wdt_set_timeout - Set the Userspace Watchdog timeout
108  *      @t: new timeout value (in seconds)
109  *
110  *      Translate the specified timeout in seconds into System Clock
111  *      terms which is what the on-chip Watchdog requires.
112  */
113 static int bfin_wdt_set_timeout(unsigned long t)
114 {
115         u32 cnt, max_t, sclk;
116         unsigned long flags;
117 
118         sclk = get_sclk();
119         max_t = -1 / sclk;
120         cnt = t * sclk;
121         stamp("maxtimeout=%us newtimeout=%lus (cnt=%#x)", max_t, t, cnt);
122 
123         if (t > max_t) {
124                 pr_warn("timeout value is too large\n");
125                 return -EINVAL;
126         }
127 
128         spin_lock_irqsave(&bfin_wdt_spinlock, flags);
129         {
130                 int run = bfin_wdt_running();
131                 bfin_wdt_stop();
132                 bfin_write_WDOG_CNT(cnt);
133                 if (run)
134                         bfin_wdt_start();
135         }
136         spin_unlock_irqrestore(&bfin_wdt_spinlock, flags);
137 
138         timeout = t;
139 
140         return 0;
141 }
142 
143 /**
144  *      bfin_wdt_open - Open the Device
145  *      @inode: inode of device
146  *      @file: file handle of device
147  *
148  *      Watchdog device is opened and started.
149  */
150 static int bfin_wdt_open(struct inode *inode, struct file *file)
151 {
152         stampit();
153 
154         if (test_and_set_bit(0, &open_check))
155                 return -EBUSY;
156 
157         if (nowayout)
158                 __module_get(THIS_MODULE);
159 
160         bfin_wdt_keepalive();
161         bfin_wdt_start();
162 
163         return nonseekable_open(inode, file);
164 }
165 
166 /**
167  *      bfin_wdt_close - Close the Device
168  *      @inode: inode of device
169  *      @file: file handle of device
170  *
171  *      Watchdog device is closed and stopped.
172  */
173 static int bfin_wdt_release(struct inode *inode, struct file *file)
174 {
175         stampit();
176 
177         if (expect_close == 42)
178                 bfin_wdt_stop();
179         else {
180                 pr_crit("Unexpected close, not stopping watchdog!\n");
181                 bfin_wdt_keepalive();
182         }
183         expect_close = 0;
184         clear_bit(0, &open_check);
185         return 0;
186 }
187 
188 /**
189  *      bfin_wdt_write - Write to Device
190  *      @file: file handle of device
191  *      @buf: buffer to write
192  *      @count: length of buffer
193  *      @ppos: offset
194  *
195  *      Pings the watchdog on write.
196  */
197 static ssize_t bfin_wdt_write(struct file *file, const char __user *data,
198                                                 size_t len, loff_t *ppos)
199 {
200         stampit();
201 
202         if (len) {
203                 if (!nowayout) {
204                         size_t i;
205 
206                         /* In case it was set long ago */
207                         expect_close = 0;
208 
209                         for (i = 0; i != len; i++) {
210                                 char c;
211                                 if (get_user(c, data + i))
212                                         return -EFAULT;
213                                 if (c == 'V')
214                                         expect_close = 42;
215                         }
216                 }
217                 bfin_wdt_keepalive();
218         }
219 
220         return len;
221 }
222 
223 /**
224  *      bfin_wdt_ioctl - Query Device
225  *      @file: file handle of device
226  *      @cmd: watchdog command
227  *      @arg: argument
228  *
229  *      Query basic information from the device or ping it, as outlined by the
230  *      watchdog API.
231  */
232 static long bfin_wdt_ioctl(struct file *file,
233                                 unsigned int cmd, unsigned long arg)
234 {
235         void __user *argp = (void __user *)arg;
236         int __user *p = argp;
237 
238         stampit();
239 
240         switch (cmd) {
241         case WDIOC_GETSUPPORT:
242                 if (copy_to_user(argp, &bfin_wdt_info, sizeof(bfin_wdt_info)))
243                         return -EFAULT;
244                 else
245                         return 0;
246         case WDIOC_GETSTATUS:
247         case WDIOC_GETBOOTSTATUS:
248                 return put_user(!!(_bfin_swrst & SWRST_RESET_WDOG), p);
249         case WDIOC_SETOPTIONS: {
250                 unsigned long flags;
251                 int options, ret = -EINVAL;
252 
253                 if (get_user(options, p))
254                         return -EFAULT;
255 
256                 spin_lock_irqsave(&bfin_wdt_spinlock, flags);
257                 if (options & WDIOS_DISABLECARD) {
258                         bfin_wdt_stop();
259                         ret = 0;
260                 }
261                 if (options & WDIOS_ENABLECARD) {
262                         bfin_wdt_start();
263                         ret = 0;
264                 }
265                 spin_unlock_irqrestore(&bfin_wdt_spinlock, flags);
266                 return ret;
267         }
268         case WDIOC_KEEPALIVE:
269                 bfin_wdt_keepalive();
270                 return 0;
271         case WDIOC_SETTIMEOUT: {
272                 int new_timeout;
273 
274                 if (get_user(new_timeout, p))
275                         return -EFAULT;
276                 if (bfin_wdt_set_timeout(new_timeout))
277                         return -EINVAL;
278         }
279         /* Fall */
280         case WDIOC_GETTIMEOUT:
281                 return put_user(timeout, p);
282         default:
283                 return -ENOTTY;
284         }
285 }
286 
287 #ifdef CONFIG_PM
288 static int state_before_suspend;
289 
290 /**
291  *      bfin_wdt_suspend - suspend the watchdog
292  *      @pdev: device being suspended
293  *      @state: requested suspend state
294  *
295  *      Remember if the watchdog was running and stop it.
296  *      TODO: is this even right?  Doesn't seem to be any
297  *            standard in the watchdog world ...
298  */
299 static int bfin_wdt_suspend(struct platform_device *pdev, pm_message_t state)
300 {
301         stampit();
302 
303         state_before_suspend = bfin_wdt_running();
304         bfin_wdt_stop();
305 
306         return 0;
307 }
308 
309 /**
310  *      bfin_wdt_resume - resume the watchdog
311  *      @pdev: device being resumed
312  *
313  *      If the watchdog was running, turn it back on.
314  */
315 static int bfin_wdt_resume(struct platform_device *pdev)
316 {
317         stampit();
318 
319         if (state_before_suspend) {
320                 bfin_wdt_set_timeout(timeout);
321                 bfin_wdt_start();
322         }
323 
324         return 0;
325 }
326 #else
327 # define bfin_wdt_suspend NULL
328 # define bfin_wdt_resume NULL
329 #endif
330 
331 static const struct file_operations bfin_wdt_fops = {
332         .owner          = THIS_MODULE,
333         .llseek         = no_llseek,
334         .write          = bfin_wdt_write,
335         .unlocked_ioctl = bfin_wdt_ioctl,
336         .open           = bfin_wdt_open,
337         .release        = bfin_wdt_release,
338 };
339 
340 static struct miscdevice bfin_wdt_miscdev = {
341         .minor    = WATCHDOG_MINOR,
342         .name     = "watchdog",
343         .fops     = &bfin_wdt_fops,
344 };
345 
346 static const struct watchdog_info bfin_wdt_info = {
347         .identity = "Blackfin Watchdog",
348         .options  = WDIOF_SETTIMEOUT |
349                     WDIOF_KEEPALIVEPING |
350                     WDIOF_MAGICCLOSE,
351 };
352 
353 /**
354  *      bfin_wdt_probe - Initialize module
355  *
356  *      Registers the misc device.  Actual device
357  *      initialization is handled by bfin_wdt_open().
358  */
359 static int bfin_wdt_probe(struct platform_device *pdev)
360 {
361         int ret;
362 
363         ret = misc_register(&bfin_wdt_miscdev);
364         if (ret) {
365                 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
366                        WATCHDOG_MINOR, ret);
367                 return ret;
368         }
369 
370         pr_info("initialized: timeout=%d sec (nowayout=%d)\n",
371                 timeout, nowayout);
372 
373         return 0;
374 }
375 
376 /**
377  *      bfin_wdt_remove - Initialize module
378  *
379  *      Unregisters the misc device.  Actual device
380  *      deinitialization is handled by bfin_wdt_close().
381  */
382 static int bfin_wdt_remove(struct platform_device *pdev)
383 {
384         misc_deregister(&bfin_wdt_miscdev);
385         return 0;
386 }
387 
388 /**
389  *      bfin_wdt_shutdown - Soft Shutdown Handler
390  *
391  *      Handles the soft shutdown event.
392  */
393 static void bfin_wdt_shutdown(struct platform_device *pdev)
394 {
395         stampit();
396 
397         bfin_wdt_stop();
398 }
399 
400 static struct platform_device *bfin_wdt_device;
401 
402 static struct platform_driver bfin_wdt_driver = {
403         .probe     = bfin_wdt_probe,
404         .remove    = bfin_wdt_remove,
405         .shutdown  = bfin_wdt_shutdown,
406         .suspend   = bfin_wdt_suspend,
407         .resume    = bfin_wdt_resume,
408         .driver    = {
409                 .name  = WATCHDOG_NAME,
410                 .owner = THIS_MODULE,
411         },
412 };
413 
414 /**
415  *      bfin_wdt_init - Initialize module
416  *
417  *      Checks the module params and registers the platform device & driver.
418  *      Real work is in the platform probe function.
419  */
420 static int __init bfin_wdt_init(void)
421 {
422         int ret;
423 
424         stampit();
425 
426         /* Check that the timeout value is within range */
427         if (bfin_wdt_set_timeout(timeout))
428                 return -EINVAL;
429 
430         /* Since this is an on-chip device and needs no board-specific
431          * resources, we'll handle all the platform device stuff here.
432          */
433         ret = platform_driver_register(&bfin_wdt_driver);
434         if (ret) {
435                 pr_err("unable to register driver\n");
436                 return ret;
437         }
438 
439         bfin_wdt_device = platform_device_register_simple(WATCHDOG_NAME,
440                                                                 -1, NULL, 0);
441         if (IS_ERR(bfin_wdt_device)) {
442                 pr_err("unable to register device\n");
443                 platform_driver_unregister(&bfin_wdt_driver);
444                 return PTR_ERR(bfin_wdt_device);
445         }
446 
447         return 0;
448 }
449 
450 /**
451  *      bfin_wdt_exit - Deinitialize module
452  *
453  *      Back out the platform device & driver steps.  Real work is in the
454  *      platform remove function.
455  */
456 static void __exit bfin_wdt_exit(void)
457 {
458         platform_device_unregister(bfin_wdt_device);
459         platform_driver_unregister(&bfin_wdt_driver);
460 }
461 
462 module_init(bfin_wdt_init);
463 module_exit(bfin_wdt_exit);
464 
465 MODULE_AUTHOR("Michele d'Amico, Mike Frysinger <vapier@gentoo.org>");
466 MODULE_DESCRIPTION("Blackfin Watchdog Device Driver");
467 MODULE_LICENSE("GPL");
468 
469 module_param(timeout, uint, 0);
470 MODULE_PARM_DESC(timeout,
471         "Watchdog timeout in seconds. (1<=timeout<=((2^32)/SCLK), default="
472                 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
473 
474 module_param(nowayout, bool, 0);
475 MODULE_PARM_DESC(nowayout,
476         "Watchdog cannot be stopped once started (default="
477                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
478 

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