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 /*
305  *	Notifier for system down
306  */
307 
308 static int wdt_notify_sys(struct notifier_block *this,
309 					unsigned long code, void *unused)
310 {
311 	if (code == SYS_DOWN || code == SYS_HALT)
312 		wdt_turnoff();
313 
314 	if (code == SYS_RESTART) {
315 		/*
316 		 * Cobalt devices have no way of rebooting themselves other
317 		 * than getting the watchdog to pull reset, so we restart the
318 		 * watchdog on reboot with no heartbeat
319 		 */
320 		wdt_change(WDT_ENABLE);
321 		pr_info("Watchdog timer is now enabled with no heartbeat - should reboot in ~1 second\n");
322 	}
323 	return NOTIFY_DONE;
324 }
325 
326 /*
327  *	The WDT needs to learn about soft shutdowns in order to
328  *	turn the timebomb registers off.
329  */
330 
331 static struct notifier_block wdt_notifier = {
332 	.notifier_call = wdt_notify_sys,
333 };
334 
335 static void __exit alim7101_wdt_unload(void)
336 {
337 	wdt_turnoff();
338 	/* Deregister */
339 	misc_deregister(&wdt_miscdev);
340 	unregister_reboot_notifier(&wdt_notifier);
341 	pci_dev_put(alim7101_pmu);
342 }
343 
344 static int __init alim7101_wdt_init(void)
345 {
346 	int rc = -EBUSY;
347 	struct pci_dev *ali1543_south;
348 	char tmp;
349 
350 	pr_info("Steve Hill <steve@navaho.co.uk>\n");
351 	alim7101_pmu = pci_get_device(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M7101,
352 		NULL);
353 	if (!alim7101_pmu) {
354 		pr_info("ALi M7101 PMU not present - WDT not set\n");
355 		return -EBUSY;
356 	}
357 
358 	/* Set the WDT in the PMU to 1 second */
359 	pci_write_config_byte(alim7101_pmu, ALI_7101_WDT, 0x02);
360 
361 	ali1543_south = pci_get_device(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M1533,
362 		NULL);
363 	if (!ali1543_south) {
364 		pr_info("ALi 1543 South-Bridge not present - WDT not set\n");
365 		goto err_out;
366 	}
367 	pci_read_config_byte(ali1543_south, 0x5e, &tmp);
368 	pci_dev_put(ali1543_south);
369 	if ((tmp & 0x1e) == 0x00) {
370 		if (!use_gpio) {
371 			pr_info("Detected old alim7101 revision 'a1d'.  If this is a cobalt board, set the 'use_gpio' module parameter.\n");
372 			goto err_out;
373 		}
374 		nowayout = 1;
375 	} else if ((tmp & 0x1e) != 0x12 && (tmp & 0x1e) != 0x00) {
376 		pr_info("ALi 1543 South-Bridge does not have the correct revision number (???1001?) - WDT not set\n");
377 		goto err_out;
378 	}
379 
380 	if (timeout < 1 || timeout > 3600) {
381 		/* arbitrary upper limit */
382 		timeout = WATCHDOG_TIMEOUT;
383 		pr_info("timeout value must be 1 <= x <= 3600, using %d\n",
384 			timeout);
385 	}
386 
387 	rc = register_reboot_notifier(&wdt_notifier);
388 	if (rc) {
389 		pr_err("cannot register reboot notifier (err=%d)\n", rc);
390 		goto err_out;
391 	}
392 
393 	rc = misc_register(&wdt_miscdev);
394 	if (rc) {
395 		pr_err("cannot register miscdev on minor=%d (err=%d)\n",
396 		       wdt_miscdev.minor, rc);
397 		goto err_out_reboot;
398 	}
399 
400 	if (nowayout)
401 		__module_get(THIS_MODULE);
402 
403 	pr_info("WDT driver for ALi M7101 initialised. timeout=%d sec (nowayout=%d)\n",
404 		timeout, nowayout);
405 	return 0;
406 
407 err_out_reboot:
408 	unregister_reboot_notifier(&wdt_notifier);
409 err_out:
410 	pci_dev_put(alim7101_pmu);
411 	return rc;
412 }
413 
414 module_init(alim7101_wdt_init);
415 module_exit(alim7101_wdt_unload);
416 
417 static DEFINE_PCI_DEVICE_TABLE(alim7101_pci_tbl) __used = {
418 	{ PCI_DEVICE(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M1533) },
419 	{ PCI_DEVICE(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M7101) },
420 	{ }
421 };
422 
423 MODULE_DEVICE_TABLE(pci, alim7101_pci_tbl);
424 
425 MODULE_AUTHOR("Steve Hill");
426 MODULE_DESCRIPTION("ALi M7101 PMU Computer Watchdog Timer driver");
427 MODULE_LICENSE("GPL");
428 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
429