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 #include <linux/module.h>
23 #include <linux/moduleparam.h>
24 #include <linux/types.h>
25 #include <linux/timer.h>
26 #include <linux/miscdevice.h>
27 #include <linux/watchdog.h>
28 #include <linux/ioport.h>
29 #include <linux/notifier.h>
30 #include <linux/reboot.h>
31 #include <linux/init.h>
32 #include <linux/fs.h>
33 #include <linux/pci.h>
34 #include <linux/io.h>
35 #include <linux/uaccess.h>
36 
37 #include <asm/system.h>
38 
39 #define OUR_NAME "alim7101_wdt"
40 #define PFX OUR_NAME ": "
41 
42 #define WDT_ENABLE 0x9C
43 #define WDT_DISABLE 0x8C
44 
45 #define ALI_7101_WDT    0x92
46 #define ALI_7101_GPIO   0x7D
47 #define ALI_7101_GPIO_O 0x7E
48 #define ALI_WDT_ARM     0x01
49 
50 /*
51  * We're going to use a 1 second timeout.
52  * If we reset the watchdog every ~250ms we should be safe.  */
53 
54 #define WDT_INTERVAL (HZ/4+1)
55 
56 /*
57  * We must not require too good response from the userspace daemon.
58  * Here we require the userspace daemon to send us a heartbeat
59  * char to /dev/watchdog every 30 seconds.
60  */
61 
62 #define WATCHDOG_TIMEOUT 30            /* 30 sec default timeout */
63 /* in seconds, will be multiplied by HZ to get seconds to wait for a ping */
64 static int timeout = WATCHDOG_TIMEOUT;
65 module_param(timeout, int, 0);
66 MODULE_PARM_DESC(timeout,
67 		"Watchdog timeout in seconds. (1<=timeout<=3600, default="
68 				__MODULE_STRING(WATCHDOG_TIMEOUT) ")");
69 
70 static int use_gpio; /* Use the pic (for a1d revision alim7101) */
71 module_param(use_gpio, int, 0);
72 MODULE_PARM_DESC(use_gpio,
73 		"Use the gpio watchdog (required by old cobalt boards).");
74 
75 static void wdt_timer_ping(unsigned long);
76 static DEFINE_TIMER(timer, wdt_timer_ping, 0, 1);
77 static unsigned long next_heartbeat;
78 static unsigned long wdt_is_open;
79 static char wdt_expect_close;
80 static struct pci_dev *alim7101_pmu;
81 
82 static int nowayout = WATCHDOG_NOWAYOUT;
83 module_param(nowayout, int, 0);
84 MODULE_PARM_DESC(nowayout,
85 		"Watchdog cannot be stopped once started (default="
86 				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
87 
88 /*
89  *	Whack the dog
90  */
91 
92 static void wdt_timer_ping(unsigned long data)
93 {
94 	/* If we got a heartbeat pulse within the WDT_US_INTERVAL
95 	 * we agree to ping the WDT
96 	 */
97 	char tmp;
98 
99 	if (time_before(jiffies, next_heartbeat)) {
100 		/* Ping the WDT (this is actually a disarm/arm sequence) */
101 		pci_read_config_byte(alim7101_pmu, 0x92, &tmp);
102 		pci_write_config_byte(alim7101_pmu,
103 					ALI_7101_WDT, (tmp & ~ALI_WDT_ARM));
104 		pci_write_config_byte(alim7101_pmu,
105 					ALI_7101_WDT, (tmp | ALI_WDT_ARM));
106 		if (use_gpio) {
107 			pci_read_config_byte(alim7101_pmu,
108 					ALI_7101_GPIO_O, &tmp);
109 			pci_write_config_byte(alim7101_pmu,
110 					ALI_7101_GPIO_O, tmp | 0x20);
111 			pci_write_config_byte(alim7101_pmu,
112 					ALI_7101_GPIO_O, tmp & ~0x20);
113 		}
114 	} else {
115 		printk(KERN_WARNING PFX
116 			"Heartbeat lost! Will not ping the watchdog\n");
117 	}
118 	/* Re-set the timer interval */
119 	mod_timer(&timer, jiffies + WDT_INTERVAL);
120 }
121 
122 /*
123  * Utility routines
124  */
125 
126 static void wdt_change(int writeval)
127 {
128 	char tmp;
129 
130 	pci_read_config_byte(alim7101_pmu, ALI_7101_WDT, &tmp);
131 	if (writeval == WDT_ENABLE) {
132 		pci_write_config_byte(alim7101_pmu,
133 					ALI_7101_WDT, (tmp | ALI_WDT_ARM));
134 		if (use_gpio) {
135 			pci_read_config_byte(alim7101_pmu,
136 					ALI_7101_GPIO_O, &tmp);
137 			pci_write_config_byte(alim7101_pmu,
138 					ALI_7101_GPIO_O, tmp & ~0x20);
139 		}
140 
141 	} else {
142 		pci_write_config_byte(alim7101_pmu,
143 					ALI_7101_WDT, (tmp & ~ALI_WDT_ARM));
144 		if (use_gpio) {
145 			pci_read_config_byte(alim7101_pmu,
146 					ALI_7101_GPIO_O, &tmp);
147 			pci_write_config_byte(alim7101_pmu,
148 					ALI_7101_GPIO_O, tmp | 0x20);
149 		}
150 	}
151 }
152 
153 static void wdt_startup(void)
154 {
155 	next_heartbeat = jiffies + (timeout * HZ);
156 
157 	/* We must enable before we kick off the timer in case the timer
158 	   occurs as we ping it */
159 
160 	wdt_change(WDT_ENABLE);
161 
162 	/* Start the timer */
163 	mod_timer(&timer, jiffies + WDT_INTERVAL);
164 
165 	printk(KERN_INFO PFX "Watchdog timer is now enabled.\n");
166 }
167 
168 static void wdt_turnoff(void)
169 {
170 	/* Stop the timer */
171 	del_timer_sync(&timer);
172 	wdt_change(WDT_DISABLE);
173 	printk(KERN_INFO PFX "Watchdog timer is now disabled...\n");
174 }
175 
176 static void wdt_keepalive(void)
177 {
178 	/* user land ping */
179 	next_heartbeat = jiffies + (timeout * HZ);
180 }
181 
182 /*
183  * /dev/watchdog handling
184  */
185 
186 static ssize_t fop_write(struct file *file, const char __user *buf,
187 						size_t count, loff_t *ppos)
188 {
189 	/* See if we got the magic character 'V' and reload the timer */
190 	if (count) {
191 		if (!nowayout) {
192 			size_t ofs;
193 
194 			/* note: just in case someone wrote the magic character
195 			 * five months ago... */
196 			wdt_expect_close = 0;
197 
198 			/* now scan */
199 			for (ofs = 0; ofs != count; ofs++) {
200 				char c;
201 				if (get_user(c, buf + ofs))
202 					return -EFAULT;
203 				if (c == 'V')
204 					wdt_expect_close = 42;
205 			}
206 		}
207 		/* someone wrote to us, we should restart timer */
208 		wdt_keepalive();
209 	}
210 	return count;
211 }
212 
213 static int fop_open(struct inode *inode, struct file *file)
214 {
215 	/* Just in case we're already talking to someone... */
216 	if (test_and_set_bit(0, &wdt_is_open))
217 		return -EBUSY;
218 	/* Good, fire up the show */
219 	wdt_startup();
220 	return nonseekable_open(inode, file);
221 }
222 
223 static int fop_close(struct inode *inode, struct file *file)
224 {
225 	if (wdt_expect_close == 42)
226 		wdt_turnoff();
227 	else {
228 		/* wim: shouldn't there be a: del_timer(&timer); */
229 		printk(KERN_CRIT PFX
230 		  "device file closed unexpectedly. Will not stop the WDT!\n");
231 	}
232 	clear_bit(0, &wdt_is_open);
233 	wdt_expect_close = 0;
234 	return 0;
235 }
236 
237 static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
238 {
239 	void __user *argp = (void __user *)arg;
240 	int __user *p = argp;
241 	static struct watchdog_info ident = {
242 		.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT
243 							| WDIOF_MAGICCLOSE,
244 		.firmware_version = 1,
245 		.identity = "ALiM7101",
246 	};
247 
248 	switch (cmd) {
249 	case WDIOC_GETSUPPORT:
250 		return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
251 	case WDIOC_GETSTATUS:
252 	case WDIOC_GETBOOTSTATUS:
253 		return put_user(0, p);
254 	case WDIOC_SETOPTIONS:
255 	{
256 		int new_options, retval = -EINVAL;
257 
258 		if (get_user(new_options, p))
259 			return -EFAULT;
260 		if (new_options & WDIOS_DISABLECARD) {
261 			wdt_turnoff();
262 			retval = 0;
263 		}
264 		if (new_options & WDIOS_ENABLECARD) {
265 			wdt_startup();
266 			retval = 0;
267 		}
268 		return retval;
269 	}
270 	case WDIOC_KEEPALIVE:
271 		wdt_keepalive();
272 		return 0;
273 	case WDIOC_SETTIMEOUT:
274 	{
275 		int new_timeout;
276 
277 		if (get_user(new_timeout, p))
278 			return -EFAULT;
279 		/* arbitrary upper limit */
280 		if (new_timeout < 1 || new_timeout > 3600)
281 			return -EINVAL;
282 		timeout = new_timeout;
283 		wdt_keepalive();
284 		/* Fall through */
285 	}
286 	case WDIOC_GETTIMEOUT:
287 		return put_user(timeout, p);
288 	default:
289 		return -ENOTTY;
290 	}
291 }
292 
293 static const struct file_operations wdt_fops = {
294 	.owner		=	THIS_MODULE,
295 	.llseek		=	no_llseek,
296 	.write		=	fop_write,
297 	.open		=	fop_open,
298 	.release	=	fop_close,
299 	.unlocked_ioctl	=	fop_ioctl,
300 };
301 
302 static struct miscdevice wdt_miscdev = {
303 	.minor	=	WATCHDOG_MINOR,
304 	.name	=	"watchdog",
305 	.fops	=	&wdt_fops,
306 };
307 
308 /*
309  *	Notifier for system down
310  */
311 
312 static int wdt_notify_sys(struct notifier_block *this,
313 					unsigned long code, void *unused)
314 {
315 	if (code == SYS_DOWN || code == SYS_HALT)
316 		wdt_turnoff();
317 
318 	if (code == SYS_RESTART) {
319 		/*
320 		 * Cobalt devices have no way of rebooting themselves other
321 		 * than getting the watchdog to pull reset, so we restart the
322 		 * watchdog on reboot with no heartbeat
323 		 */
324 		wdt_change(WDT_ENABLE);
325 		printk(KERN_INFO PFX "Watchdog timer is now enabled "
326 			"with no heartbeat - should reboot in ~1 second.\n");
327 	}
328 	return NOTIFY_DONE;
329 }
330 
331 /*
332  *	The WDT needs to learn about soft shutdowns in order to
333  *	turn the timebomb registers off.
334  */
335 
336 static struct notifier_block wdt_notifier = {
337 	.notifier_call = wdt_notify_sys,
338 };
339 
340 static void __exit alim7101_wdt_unload(void)
341 {
342 	wdt_turnoff();
343 	/* Deregister */
344 	misc_deregister(&wdt_miscdev);
345 	unregister_reboot_notifier(&wdt_notifier);
346 	pci_dev_put(alim7101_pmu);
347 }
348 
349 static int __init alim7101_wdt_init(void)
350 {
351 	int rc = -EBUSY;
352 	struct pci_dev *ali1543_south;
353 	char tmp;
354 
355 	printk(KERN_INFO PFX "Steve Hill <steve@navaho.co.uk>.\n");
356 	alim7101_pmu = pci_get_device(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M7101,
357 		NULL);
358 	if (!alim7101_pmu) {
359 		printk(KERN_INFO PFX
360 			"ALi M7101 PMU not present - WDT not set\n");
361 		return -EBUSY;
362 	}
363 
364 	/* Set the WDT in the PMU to 1 second */
365 	pci_write_config_byte(alim7101_pmu, ALI_7101_WDT, 0x02);
366 
367 	ali1543_south = pci_get_device(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M1533,
368 		NULL);
369 	if (!ali1543_south) {
370 		printk(KERN_INFO PFX
371 			"ALi 1543 South-Bridge not present - WDT not set\n");
372 		goto err_out;
373 	}
374 	pci_read_config_byte(ali1543_south, 0x5e, &tmp);
375 	pci_dev_put(ali1543_south);
376 	if ((tmp & 0x1e) == 0x00) {
377 		if (!use_gpio) {
378 			printk(KERN_INFO PFX
379 				"Detected old alim7101 revision 'a1d'.  "
380 				"If this is a cobalt board, set the 'use_gpio' "
381 				"module parameter.\n");
382 			goto err_out;
383 		}
384 		nowayout = 1;
385 	} else if ((tmp & 0x1e) != 0x12 && (tmp & 0x1e) != 0x00) {
386 		printk(KERN_INFO PFX
387 			"ALi 1543 South-Bridge does not have the correct "
388 			"revision number (???1001?) - WDT not set\n");
389 		goto err_out;
390 	}
391 
392 	if (timeout < 1 || timeout > 3600) {
393 		/* arbitrary upper limit */
394 		timeout = WATCHDOG_TIMEOUT;
395 		printk(KERN_INFO PFX
396 			"timeout value must be 1 <= x <= 3600, using %d\n",
397 								timeout);
398 	}
399 
400 	rc = register_reboot_notifier(&wdt_notifier);
401 	if (rc) {
402 		printk(KERN_ERR PFX
403 			"cannot register reboot notifier (err=%d)\n", rc);
404 		goto err_out;
405 	}
406 
407 	rc = misc_register(&wdt_miscdev);
408 	if (rc) {
409 		printk(KERN_ERR PFX
410 			"cannot register miscdev on minor=%d (err=%d)\n",
411 			wdt_miscdev.minor, rc);
412 		goto err_out_reboot;
413 	}
414 
415 	if (nowayout)
416 		__module_get(THIS_MODULE);
417 
418 	printk(KERN_INFO PFX "WDT driver for ALi M7101 initialised. "
419 					"timeout=%d sec (nowayout=%d)\n",
420 		timeout, nowayout);
421 	return 0;
422 
423 err_out_reboot:
424 	unregister_reboot_notifier(&wdt_notifier);
425 err_out:
426 	pci_dev_put(alim7101_pmu);
427 	return rc;
428 }
429 
430 module_init(alim7101_wdt_init);
431 module_exit(alim7101_wdt_unload);
432 
433 static struct pci_device_id alim7101_pci_tbl[] __devinitdata = {
434 	{ PCI_DEVICE(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M1533) },
435 	{ PCI_DEVICE(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M7101) },
436 	{ }
437 };
438 
439 MODULE_DEVICE_TABLE(pci, alim7101_pci_tbl);
440 
441 MODULE_AUTHOR("Steve Hill");
442 MODULE_DESCRIPTION("ALi M7101 PMU Computer Watchdog Timer driver");
443 MODULE_LICENSE("GPL");
444 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
445