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Linux/drivers/watchdog/alim7101_wdt.c

  1 /*
  2  *      ALi M7101 PMU Computer Watchdog Timer driver
  3  *
  4  *      Based on w83877f_wdt.c by Scott Jennings <linuxdrivers@oro.net>
  5  *      and the Cobalt kernel WDT timer driver by Tim Hockin
  6  *                                            <thockin@cobaltnet.com>
  7  *
  8  *      (c)2002 Steve Hill <steve@navaho.co.uk>
  9  *
 10  *  This WDT driver is different from most other Linux WDT
 11  *  drivers in that the driver will ping the watchdog by itself,
 12  *  because this particular WDT has a very short timeout (1.6
 13  *  seconds) and it would be insane to count on any userspace
 14  *  daemon always getting scheduled within that time frame.
 15  *
 16  *  Additions:
 17  *   Aug 23, 2004 - Added use_gpio module parameter for use on revision a1d PMUs
 18  *                  found on very old cobalt hardware.
 19  *                  -- Mike Waychison <michael.waychison@sun.com>
 20  */
 21 
 22 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 23 
 24 #include <linux/module.h>
 25 #include <linux/moduleparam.h>
 26 #include <linux/types.h>
 27 #include <linux/timer.h>
 28 #include <linux/miscdevice.h>
 29 #include <linux/watchdog.h>
 30 #include <linux/ioport.h>
 31 #include <linux/notifier.h>
 32 #include <linux/reboot.h>
 33 #include <linux/init.h>
 34 #include <linux/fs.h>
 35 #include <linux/pci.h>
 36 #include <linux/io.h>
 37 #include <linux/uaccess.h>
 38 
 39 
 40 #define WDT_ENABLE 0x9C
 41 #define WDT_DISABLE 0x8C
 42 
 43 #define ALI_7101_WDT    0x92
 44 #define ALI_7101_GPIO   0x7D
 45 #define ALI_7101_GPIO_O 0x7E
 46 #define ALI_WDT_ARM     0x01
 47 
 48 /*
 49  * We're going to use a 1 second timeout.
 50  * If we reset the watchdog every ~250ms we should be safe.  */
 51 
 52 #define WDT_INTERVAL (HZ/4+1)
 53 
 54 /*
 55  * We must not require too good response from the userspace daemon.
 56  * Here we require the userspace daemon to send us a heartbeat
 57  * char to /dev/watchdog every 30 seconds.
 58  */
 59 
 60 #define WATCHDOG_TIMEOUT 30            /* 30 sec default timeout */
 61 /* in seconds, will be multiplied by HZ to get seconds to wait for a ping */
 62 static int timeout = WATCHDOG_TIMEOUT;
 63 module_param(timeout, int, 0);
 64 MODULE_PARM_DESC(timeout,
 65                 "Watchdog timeout in seconds. (1<=timeout<=3600, default="
 66                                 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
 67 
 68 static int use_gpio; /* Use the pic (for a1d revision alim7101) */
 69 module_param(use_gpio, int, 0);
 70 MODULE_PARM_DESC(use_gpio,
 71                 "Use the gpio watchdog (required by old cobalt boards).");
 72 
 73 static void wdt_timer_ping(unsigned long);
 74 static DEFINE_TIMER(timer, wdt_timer_ping, 0, 1);
 75 static unsigned long next_heartbeat;
 76 static unsigned long wdt_is_open;
 77 static char wdt_expect_close;
 78 static struct pci_dev *alim7101_pmu;
 79 
 80 static bool nowayout = WATCHDOG_NOWAYOUT;
 81 module_param(nowayout, bool, 0);
 82 MODULE_PARM_DESC(nowayout,
 83                 "Watchdog cannot be stopped once started (default="
 84                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 85 
 86 /*
 87  *      Whack the dog
 88  */
 89 
 90 static void wdt_timer_ping(unsigned long data)
 91 {
 92         /* If we got a heartbeat pulse within the WDT_US_INTERVAL
 93          * we agree to ping the WDT
 94          */
 95         char tmp;
 96 
 97         if (time_before(jiffies, next_heartbeat)) {
 98                 /* Ping the WDT (this is actually a disarm/arm sequence) */
 99                 pci_read_config_byte(alim7101_pmu, 0x92, &tmp);
100                 pci_write_config_byte(alim7101_pmu,
101                                         ALI_7101_WDT, (tmp & ~ALI_WDT_ARM));
102                 pci_write_config_byte(alim7101_pmu,
103                                         ALI_7101_WDT, (tmp | ALI_WDT_ARM));
104                 if (use_gpio) {
105                         pci_read_config_byte(alim7101_pmu,
106                                         ALI_7101_GPIO_O, &tmp);
107                         pci_write_config_byte(alim7101_pmu,
108                                         ALI_7101_GPIO_O, tmp | 0x20);
109                         pci_write_config_byte(alim7101_pmu,
110                                         ALI_7101_GPIO_O, tmp & ~0x20);
111                 }
112         } else {
113                 pr_warn("Heartbeat lost! Will not ping the watchdog\n");
114         }
115         /* Re-set the timer interval */
116         mod_timer(&timer, jiffies + WDT_INTERVAL);
117 }
118 
119 /*
120  * Utility routines
121  */
122 
123 static void wdt_change(int writeval)
124 {
125         char tmp;
126 
127         pci_read_config_byte(alim7101_pmu, ALI_7101_WDT, &tmp);
128         if (writeval == WDT_ENABLE) {
129                 pci_write_config_byte(alim7101_pmu,
130                                         ALI_7101_WDT, (tmp | ALI_WDT_ARM));
131                 if (use_gpio) {
132                         pci_read_config_byte(alim7101_pmu,
133                                         ALI_7101_GPIO_O, &tmp);
134                         pci_write_config_byte(alim7101_pmu,
135                                         ALI_7101_GPIO_O, tmp & ~0x20);
136                 }
137 
138         } else {
139                 pci_write_config_byte(alim7101_pmu,
140                                         ALI_7101_WDT, (tmp & ~ALI_WDT_ARM));
141                 if (use_gpio) {
142                         pci_read_config_byte(alim7101_pmu,
143                                         ALI_7101_GPIO_O, &tmp);
144                         pci_write_config_byte(alim7101_pmu,
145                                         ALI_7101_GPIO_O, tmp | 0x20);
146                 }
147         }
148 }
149 
150 static void wdt_startup(void)
151 {
152         next_heartbeat = jiffies + (timeout * HZ);
153 
154         /* We must enable before we kick off the timer in case the timer
155            occurs as we ping it */
156 
157         wdt_change(WDT_ENABLE);
158 
159         /* Start the timer */
160         mod_timer(&timer, jiffies + WDT_INTERVAL);
161 
162         pr_info("Watchdog timer is now enabled\n");
163 }
164 
165 static void wdt_turnoff(void)
166 {
167         /* Stop the timer */
168         del_timer_sync(&timer);
169         wdt_change(WDT_DISABLE);
170         pr_info("Watchdog timer is now disabled...\n");
171 }
172 
173 static void wdt_keepalive(void)
174 {
175         /* user land ping */
176         next_heartbeat = jiffies + (timeout * HZ);
177 }
178 
179 /*
180  * /dev/watchdog handling
181  */
182 
183 static ssize_t fop_write(struct file *file, const char __user *buf,
184                                                 size_t count, loff_t *ppos)
185 {
186         /* See if we got the magic character 'V' and reload the timer */
187         if (count) {
188                 if (!nowayout) {
189                         size_t ofs;
190 
191                         /* note: just in case someone wrote the magic character
192                          * five months ago... */
193                         wdt_expect_close = 0;
194 
195                         /* now scan */
196                         for (ofs = 0; ofs != count; ofs++) {
197                                 char c;
198                                 if (get_user(c, buf + ofs))
199                                         return -EFAULT;
200                                 if (c == 'V')
201                                         wdt_expect_close = 42;
202                         }
203                 }
204                 /* someone wrote to us, we should restart timer */
205                 wdt_keepalive();
206         }
207         return count;
208 }
209 
210 static int fop_open(struct inode *inode, struct file *file)
211 {
212         /* Just in case we're already talking to someone... */
213         if (test_and_set_bit(0, &wdt_is_open))
214                 return -EBUSY;
215         /* Good, fire up the show */
216         wdt_startup();
217         return nonseekable_open(inode, file);
218 }
219 
220 static int fop_close(struct inode *inode, struct file *file)
221 {
222         if (wdt_expect_close == 42)
223                 wdt_turnoff();
224         else {
225                 /* wim: shouldn't there be a: del_timer(&timer); */
226                 pr_crit("device file closed unexpectedly. Will not stop the WDT!\n");
227         }
228         clear_bit(0, &wdt_is_open);
229         wdt_expect_close = 0;
230         return 0;
231 }
232 
233 static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
234 {
235         void __user *argp = (void __user *)arg;
236         int __user *p = argp;
237         static const struct watchdog_info ident = {
238                 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT
239                                                         | WDIOF_MAGICCLOSE,
240                 .firmware_version = 1,
241                 .identity = "ALiM7101",
242         };
243 
244         switch (cmd) {
245         case WDIOC_GETSUPPORT:
246                 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
247         case WDIOC_GETSTATUS:
248         case WDIOC_GETBOOTSTATUS:
249                 return put_user(0, p);
250         case WDIOC_SETOPTIONS:
251         {
252                 int new_options, retval = -EINVAL;
253 
254                 if (get_user(new_options, p))
255                         return -EFAULT;
256                 if (new_options & WDIOS_DISABLECARD) {
257                         wdt_turnoff();
258                         retval = 0;
259                 }
260                 if (new_options & WDIOS_ENABLECARD) {
261                         wdt_startup();
262                         retval = 0;
263                 }
264                 return retval;
265         }
266         case WDIOC_KEEPALIVE:
267                 wdt_keepalive();
268                 return 0;
269         case WDIOC_SETTIMEOUT:
270         {
271                 int new_timeout;
272 
273                 if (get_user(new_timeout, p))
274                         return -EFAULT;
275                 /* arbitrary upper limit */
276                 if (new_timeout < 1 || new_timeout > 3600)
277                         return -EINVAL;
278                 timeout = new_timeout;
279                 wdt_keepalive();
280                 /* Fall through */
281         }
282         case WDIOC_GETTIMEOUT:
283                 return put_user(timeout, p);
284         default:
285                 return -ENOTTY;
286         }
287 }
288 
289 static const struct file_operations wdt_fops = {
290         .owner          =       THIS_MODULE,
291         .llseek         =       no_llseek,
292         .write          =       fop_write,
293         .open           =       fop_open,
294         .release        =       fop_close,
295         .unlocked_ioctl =       fop_ioctl,
296 };
297 
298 static struct miscdevice wdt_miscdev = {
299         .minor  =       WATCHDOG_MINOR,
300         .name   =       "watchdog",
301         .fops   =       &wdt_fops,
302 };
303 
304 static int wdt_restart_handle(struct notifier_block *this, unsigned long mode,
305                               void *cmd)
306 {
307         /*
308          * Cobalt devices have no way of rebooting themselves other
309          * than getting the watchdog to pull reset, so we restart the
310          * watchdog on reboot with no heartbeat.
311          */
312         wdt_change(WDT_ENABLE);
313 
314         /* loop until the watchdog fires */
315         while (true)
316                 ;
317 
318         return NOTIFY_DONE;
319 }
320 
321 static struct notifier_block wdt_restart_handler = {
322         .notifier_call = wdt_restart_handle,
323         .priority = 128,
324 };
325 
326 /*
327  *      Notifier for system down
328  */
329 
330 static int wdt_notify_sys(struct notifier_block *this,
331                                         unsigned long code, void *unused)
332 {
333         if (code == SYS_DOWN || code == SYS_HALT)
334                 wdt_turnoff();
335 
336         return NOTIFY_DONE;
337 }
338 
339 /*
340  *      The WDT needs to learn about soft shutdowns in order to
341  *      turn the timebomb registers off.
342  */
343 
344 static struct notifier_block wdt_notifier = {
345         .notifier_call = wdt_notify_sys,
346 };
347 
348 static void __exit alim7101_wdt_unload(void)
349 {
350         wdt_turnoff();
351         /* Deregister */
352         misc_deregister(&wdt_miscdev);
353         unregister_reboot_notifier(&wdt_notifier);
354         unregister_restart_handler(&wdt_restart_handler);
355         pci_dev_put(alim7101_pmu);
356 }
357 
358 static int __init alim7101_wdt_init(void)
359 {
360         int rc = -EBUSY;
361         struct pci_dev *ali1543_south;
362         char tmp;
363 
364         pr_info("Steve Hill <steve@navaho.co.uk>\n");
365         alim7101_pmu = pci_get_device(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M7101,
366                 NULL);
367         if (!alim7101_pmu) {
368                 pr_info("ALi M7101 PMU not present - WDT not set\n");
369                 return -EBUSY;
370         }
371 
372         /* Set the WDT in the PMU to 1 second */
373         pci_write_config_byte(alim7101_pmu, ALI_7101_WDT, 0x02);
374 
375         ali1543_south = pci_get_device(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M1533,
376                 NULL);
377         if (!ali1543_south) {
378                 pr_info("ALi 1543 South-Bridge not present - WDT not set\n");
379                 goto err_out;
380         }
381         pci_read_config_byte(ali1543_south, 0x5e, &tmp);
382         pci_dev_put(ali1543_south);
383         if ((tmp & 0x1e) == 0x00) {
384                 if (!use_gpio) {
385                         pr_info("Detected old alim7101 revision 'a1d'.  If this is a cobalt board, set the 'use_gpio' module parameter.\n");
386                         goto err_out;
387                 }
388                 nowayout = 1;
389         } else if ((tmp & 0x1e) != 0x12 && (tmp & 0x1e) != 0x00) {
390                 pr_info("ALi 1543 South-Bridge does not have the correct revision number (???1001?) - WDT not set\n");
391                 goto err_out;
392         }
393 
394         if (timeout < 1 || timeout > 3600) {
395                 /* arbitrary upper limit */
396                 timeout = WATCHDOG_TIMEOUT;
397                 pr_info("timeout value must be 1 <= x <= 3600, using %d\n",
398                         timeout);
399         }
400 
401         rc = register_reboot_notifier(&wdt_notifier);
402         if (rc) {
403                 pr_err("cannot register reboot notifier (err=%d)\n", rc);
404                 goto err_out;
405         }
406 
407         rc = register_restart_handler(&wdt_restart_handler);
408         if (rc) {
409                 pr_err("cannot register restart handler (err=%d)\n", rc);
410                 goto err_out_reboot;
411         }
412 
413         rc = misc_register(&wdt_miscdev);
414         if (rc) {
415                 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
416                        wdt_miscdev.minor, rc);
417                 goto err_out_restart;
418         }
419 
420         if (nowayout)
421                 __module_get(THIS_MODULE);
422 
423         pr_info("WDT driver for ALi M7101 initialised. timeout=%d sec (nowayout=%d)\n",
424                 timeout, nowayout);
425         return 0;
426 
427 err_out_restart:
428         unregister_restart_handler(&wdt_restart_handler);
429 err_out_reboot:
430         unregister_reboot_notifier(&wdt_notifier);
431 err_out:
432         pci_dev_put(alim7101_pmu);
433         return rc;
434 }
435 
436 module_init(alim7101_wdt_init);
437 module_exit(alim7101_wdt_unload);
438 
439 static const struct pci_device_id alim7101_pci_tbl[] __used = {
440         { PCI_DEVICE(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M1533) },
441         { PCI_DEVICE(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M7101) },
442         { }
443 };
444 
445 MODULE_DEVICE_TABLE(pci, alim7101_pci_tbl);
446 
447 MODULE_AUTHOR("Steve Hill");
448 MODULE_DESCRIPTION("ALi M7101 PMU Computer Watchdog Timer driver");
449 MODULE_LICENSE("GPL");
450 

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