xref: /openbmc/linux/drivers/watchdog/nv_tco.c (revision 3a973109)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *	nv_tco 0.01:	TCO timer driver for NV chipsets
4  *
5  *	(c) Copyright 2005 Google Inc., All Rights Reserved.
6  *
7  *	Based off i8xx_tco.c:
8  *	(c) Copyright 2000 kernel concepts <nils@kernelconcepts.de>, All Rights
9  *	Reserved.
10  *				https://www.kernelconcepts.de
11  *
12  *	TCO timer driver for NV chipsets
13  *	based on softdog.c by Alan Cox <alan@redhat.com>
14  */
15 
16 /*
17  *	Includes, defines, variables, module parameters, ...
18  */
19 
20 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
21 
22 #include <linux/module.h>
23 #include <linux/moduleparam.h>
24 #include <linux/types.h>
25 #include <linux/miscdevice.h>
26 #include <linux/watchdog.h>
27 #include <linux/init.h>
28 #include <linux/fs.h>
29 #include <linux/pci.h>
30 #include <linux/ioport.h>
31 #include <linux/jiffies.h>
32 #include <linux/platform_device.h>
33 #include <linux/uaccess.h>
34 #include <linux/io.h>
35 
36 #include "nv_tco.h"
37 
38 /* Module and version information */
39 #define TCO_VERSION "0.01"
40 #define TCO_MODULE_NAME "NV_TCO"
41 #define TCO_DRIVER_NAME   TCO_MODULE_NAME ", v" TCO_VERSION
42 
43 /* internal variables */
44 static unsigned int tcobase;
45 static DEFINE_SPINLOCK(tco_lock);	/* Guards the hardware */
46 static unsigned long timer_alive;
47 static char tco_expect_close;
48 static struct pci_dev *tco_pci;
49 
50 /* the watchdog platform device */
51 static struct platform_device *nv_tco_platform_device;
52 
53 /* module parameters */
54 #define WATCHDOG_HEARTBEAT 30	/* 30 sec default heartbeat (2<heartbeat<39) */
55 static int heartbeat = WATCHDOG_HEARTBEAT;  /* in seconds */
56 module_param(heartbeat, int, 0);
57 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds. (2<heartbeat<39, "
58 			    "default=" __MODULE_STRING(WATCHDOG_HEARTBEAT) ")");
59 
60 static bool nowayout = WATCHDOG_NOWAYOUT;
61 module_param(nowayout, bool, 0);
62 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started"
63 		" (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
64 
65 /*
66  * Some TCO specific functions
67  */
seconds_to_ticks(int seconds)68 static inline unsigned char seconds_to_ticks(int seconds)
69 {
70 	/* the internal timer is stored as ticks which decrement
71 	 * every 0.6 seconds */
72 	return (seconds * 10) / 6;
73 }
74 
tco_timer_start(void)75 static void tco_timer_start(void)
76 {
77 	u32 val;
78 	unsigned long flags;
79 
80 	spin_lock_irqsave(&tco_lock, flags);
81 	val = inl(TCO_CNT(tcobase));
82 	val &= ~TCO_CNT_TCOHALT;
83 	outl(val, TCO_CNT(tcobase));
84 	spin_unlock_irqrestore(&tco_lock, flags);
85 }
86 
tco_timer_stop(void)87 static void tco_timer_stop(void)
88 {
89 	u32 val;
90 	unsigned long flags;
91 
92 	spin_lock_irqsave(&tco_lock, flags);
93 	val = inl(TCO_CNT(tcobase));
94 	val |= TCO_CNT_TCOHALT;
95 	outl(val, TCO_CNT(tcobase));
96 	spin_unlock_irqrestore(&tco_lock, flags);
97 }
98 
tco_timer_keepalive(void)99 static void tco_timer_keepalive(void)
100 {
101 	unsigned long flags;
102 
103 	spin_lock_irqsave(&tco_lock, flags);
104 	outb(0x01, TCO_RLD(tcobase));
105 	spin_unlock_irqrestore(&tco_lock, flags);
106 }
107 
tco_timer_set_heartbeat(int t)108 static int tco_timer_set_heartbeat(int t)
109 {
110 	int ret = 0;
111 	unsigned char tmrval;
112 	unsigned long flags;
113 	u8 val;
114 
115 	/*
116 	 * note seconds_to_ticks(t) > t, so if t > 0x3f, so is
117 	 * tmrval=seconds_to_ticks(t).  Check that the count in seconds isn't
118 	 * out of range on it's own (to avoid overflow in tmrval).
119 	 */
120 	if (t < 0 || t > 0x3f)
121 		return -EINVAL;
122 	tmrval = seconds_to_ticks(t);
123 
124 	/* "Values of 0h-3h are ignored and should not be attempted" */
125 	if (tmrval > 0x3f || tmrval < 0x04)
126 		return -EINVAL;
127 
128 	/* Write new heartbeat to watchdog */
129 	spin_lock_irqsave(&tco_lock, flags);
130 	val = inb(TCO_TMR(tcobase));
131 	val &= 0xc0;
132 	val |= tmrval;
133 	outb(val, TCO_TMR(tcobase));
134 	val = inb(TCO_TMR(tcobase));
135 
136 	if ((val & 0x3f) != tmrval)
137 		ret = -EINVAL;
138 	spin_unlock_irqrestore(&tco_lock, flags);
139 
140 	if (ret)
141 		return ret;
142 
143 	heartbeat = t;
144 	return 0;
145 }
146 
147 /*
148  *	/dev/watchdog handling
149  */
150 
nv_tco_open(struct inode * inode,struct file * file)151 static int nv_tco_open(struct inode *inode, struct file *file)
152 {
153 	/* /dev/watchdog can only be opened once */
154 	if (test_and_set_bit(0, &timer_alive))
155 		return -EBUSY;
156 
157 	/* Reload and activate timer */
158 	tco_timer_keepalive();
159 	tco_timer_start();
160 	return stream_open(inode, file);
161 }
162 
nv_tco_release(struct inode * inode,struct file * file)163 static int nv_tco_release(struct inode *inode, struct file *file)
164 {
165 	/* Shut off the timer */
166 	if (tco_expect_close == 42) {
167 		tco_timer_stop();
168 	} else {
169 		pr_crit("Unexpected close, not stopping watchdog!\n");
170 		tco_timer_keepalive();
171 	}
172 	clear_bit(0, &timer_alive);
173 	tco_expect_close = 0;
174 	return 0;
175 }
176 
nv_tco_write(struct file * file,const char __user * data,size_t len,loff_t * ppos)177 static ssize_t nv_tco_write(struct file *file, const char __user *data,
178 			    size_t len, loff_t *ppos)
179 {
180 	/* See if we got the magic character 'V' and reload the timer */
181 	if (len) {
182 		if (!nowayout) {
183 			size_t i;
184 
185 			/*
186 			 * note: just in case someone wrote the magic character
187 			 * five months ago...
188 			 */
189 			tco_expect_close = 0;
190 
191 			/*
192 			 * scan to see whether or not we got the magic
193 			 * character
194 			 */
195 			for (i = 0; i != len; i++) {
196 				char c;
197 				if (get_user(c, data + i))
198 					return -EFAULT;
199 				if (c == 'V')
200 					tco_expect_close = 42;
201 			}
202 		}
203 
204 		/* someone wrote to us, we should reload the timer */
205 		tco_timer_keepalive();
206 	}
207 	return len;
208 }
209 
nv_tco_ioctl(struct file * file,unsigned int cmd,unsigned long arg)210 static long nv_tco_ioctl(struct file *file, unsigned int cmd,
211 			 unsigned long arg)
212 {
213 	int new_options, retval = -EINVAL;
214 	int new_heartbeat;
215 	void __user *argp = (void __user *)arg;
216 	int __user *p = argp;
217 	static const struct watchdog_info ident = {
218 		.options =		WDIOF_SETTIMEOUT |
219 					WDIOF_KEEPALIVEPING |
220 					WDIOF_MAGICCLOSE,
221 		.firmware_version =	0,
222 		.identity =		TCO_MODULE_NAME,
223 	};
224 
225 	switch (cmd) {
226 	case WDIOC_GETSUPPORT:
227 		return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
228 	case WDIOC_GETSTATUS:
229 	case WDIOC_GETBOOTSTATUS:
230 		return put_user(0, p);
231 	case WDIOC_SETOPTIONS:
232 		if (get_user(new_options, p))
233 			return -EFAULT;
234 		if (new_options & WDIOS_DISABLECARD) {
235 			tco_timer_stop();
236 			retval = 0;
237 		}
238 		if (new_options & WDIOS_ENABLECARD) {
239 			tco_timer_keepalive();
240 			tco_timer_start();
241 			retval = 0;
242 		}
243 		return retval;
244 	case WDIOC_KEEPALIVE:
245 		tco_timer_keepalive();
246 		return 0;
247 	case WDIOC_SETTIMEOUT:
248 		if (get_user(new_heartbeat, p))
249 			return -EFAULT;
250 		if (tco_timer_set_heartbeat(new_heartbeat))
251 			return -EINVAL;
252 		tco_timer_keepalive();
253 		fallthrough;
254 	case WDIOC_GETTIMEOUT:
255 		return put_user(heartbeat, p);
256 	default:
257 		return -ENOTTY;
258 	}
259 }
260 
261 /*
262  *	Kernel Interfaces
263  */
264 
265 static const struct file_operations nv_tco_fops = {
266 	.owner =		THIS_MODULE,
267 	.llseek =		no_llseek,
268 	.write =		nv_tco_write,
269 	.unlocked_ioctl =	nv_tco_ioctl,
270 	.compat_ioctl =		compat_ptr_ioctl,
271 	.open =			nv_tco_open,
272 	.release =		nv_tco_release,
273 };
274 
275 static struct miscdevice nv_tco_miscdev = {
276 	.minor =	WATCHDOG_MINOR,
277 	.name =		"watchdog",
278 	.fops =		&nv_tco_fops,
279 };
280 
281 /*
282  * Data for PCI driver interface
283  *
284  * This data only exists for exporting the supported
285  * PCI ids via MODULE_DEVICE_TABLE.  We do not actually
286  * register a pci_driver, because someone else might one day
287  * want to register another driver on the same PCI id.
288  */
289 static const struct pci_device_id tco_pci_tbl[] = {
290 	{ PCI_VENDOR_ID_NVIDIA, PCI_DEVICE_ID_NVIDIA_NFORCE_MCP51_SMBUS,
291 	  PCI_ANY_ID, PCI_ANY_ID, },
292 	{ PCI_VENDOR_ID_NVIDIA, PCI_DEVICE_ID_NVIDIA_NFORCE_MCP55_SMBUS,
293 	  PCI_ANY_ID, PCI_ANY_ID, },
294 	{ PCI_VENDOR_ID_NVIDIA, PCI_DEVICE_ID_NVIDIA_NFORCE_MCP78S_SMBUS,
295 	  PCI_ANY_ID, PCI_ANY_ID, },
296 	{ PCI_VENDOR_ID_NVIDIA, PCI_DEVICE_ID_NVIDIA_NFORCE_MCP79_SMBUS,
297 	  PCI_ANY_ID, PCI_ANY_ID, },
298 	{ 0, },			/* End of list */
299 };
300 MODULE_DEVICE_TABLE(pci, tco_pci_tbl);
301 
302 /*
303  *	Init & exit routines
304  */
305 
nv_tco_getdevice(void)306 static unsigned char nv_tco_getdevice(void)
307 {
308 	struct pci_dev *dev = NULL;
309 	u32 val;
310 
311 	/* Find the PCI device */
312 	for_each_pci_dev(dev) {
313 		if (pci_match_id(tco_pci_tbl, dev) != NULL) {
314 			tco_pci = dev;
315 			break;
316 		}
317 	}
318 
319 	if (!tco_pci)
320 		return 0;
321 
322 	/* Find the base io port */
323 	pci_read_config_dword(tco_pci, 0x64, &val);
324 	val &= 0xffff;
325 	if (val == 0x0001 || val == 0x0000) {
326 		/* Something is wrong here, bar isn't setup */
327 		pr_err("failed to get tcobase address\n");
328 		return 0;
329 	}
330 	val &= 0xff00;
331 	tcobase = val + 0x40;
332 
333 	if (!request_region(tcobase, 0x10, "NV TCO")) {
334 		pr_err("I/O address 0x%04x already in use\n", tcobase);
335 		return 0;
336 	}
337 
338 	/* Set a reasonable heartbeat before we stop the timer */
339 	tco_timer_set_heartbeat(30);
340 
341 	/*
342 	 * Stop the TCO before we change anything so we don't race with
343 	 * a zeroed timer.
344 	 */
345 	tco_timer_keepalive();
346 	tco_timer_stop();
347 
348 	/* Disable SMI caused by TCO */
349 	if (!request_region(MCP51_SMI_EN(tcobase), 4, "NV TCO")) {
350 		pr_err("I/O address 0x%04x already in use\n",
351 		       MCP51_SMI_EN(tcobase));
352 		goto out;
353 	}
354 	val = inl(MCP51_SMI_EN(tcobase));
355 	val &= ~MCP51_SMI_EN_TCO;
356 	outl(val, MCP51_SMI_EN(tcobase));
357 	val = inl(MCP51_SMI_EN(tcobase));
358 	release_region(MCP51_SMI_EN(tcobase), 4);
359 	if (val & MCP51_SMI_EN_TCO) {
360 		pr_err("Could not disable SMI caused by TCO\n");
361 		goto out;
362 	}
363 
364 	/* Check chipset's NO_REBOOT bit */
365 	pci_read_config_dword(tco_pci, MCP51_SMBUS_SETUP_B, &val);
366 	val |= MCP51_SMBUS_SETUP_B_TCO_REBOOT;
367 	pci_write_config_dword(tco_pci, MCP51_SMBUS_SETUP_B, val);
368 	pci_read_config_dword(tco_pci, MCP51_SMBUS_SETUP_B, &val);
369 	if (!(val & MCP51_SMBUS_SETUP_B_TCO_REBOOT)) {
370 		pr_err("failed to reset NO_REBOOT flag, reboot disabled by hardware\n");
371 		goto out;
372 	}
373 
374 	return 1;
375 out:
376 	release_region(tcobase, 0x10);
377 	return 0;
378 }
379 
nv_tco_init(struct platform_device * dev)380 static int nv_tco_init(struct platform_device *dev)
381 {
382 	int ret;
383 
384 	/* Check whether or not the hardware watchdog is there */
385 	if (!nv_tco_getdevice())
386 		return -ENODEV;
387 
388 	/* Check to see if last reboot was due to watchdog timeout */
389 	pr_info("Watchdog reboot %sdetected\n",
390 		inl(TCO_STS(tcobase)) & TCO_STS_TCO2TO_STS ? "" : "not ");
391 
392 	/* Clear out the old status */
393 	outl(TCO_STS_RESET, TCO_STS(tcobase));
394 
395 	/*
396 	 * Check that the heartbeat value is within it's range.
397 	 * If not, reset to the default.
398 	 */
399 	if (tco_timer_set_heartbeat(heartbeat)) {
400 		heartbeat = WATCHDOG_HEARTBEAT;
401 		tco_timer_set_heartbeat(heartbeat);
402 		pr_info("heartbeat value must be 2<heartbeat<39, using %d\n",
403 			heartbeat);
404 	}
405 
406 	ret = misc_register(&nv_tco_miscdev);
407 	if (ret != 0) {
408 		pr_err("cannot register miscdev on minor=%d (err=%d)\n",
409 		       WATCHDOG_MINOR, ret);
410 		goto unreg_region;
411 	}
412 
413 	clear_bit(0, &timer_alive);
414 
415 	tco_timer_stop();
416 
417 	pr_info("initialized (0x%04x). heartbeat=%d sec (nowayout=%d)\n",
418 		tcobase, heartbeat, nowayout);
419 
420 	return 0;
421 
422 unreg_region:
423 	release_region(tcobase, 0x10);
424 	return ret;
425 }
426 
nv_tco_cleanup(void)427 static void nv_tco_cleanup(void)
428 {
429 	u32 val;
430 
431 	/* Stop the timer before we leave */
432 	if (!nowayout)
433 		tco_timer_stop();
434 
435 	/* Set the NO_REBOOT bit to prevent later reboots, just for sure */
436 	pci_read_config_dword(tco_pci, MCP51_SMBUS_SETUP_B, &val);
437 	val &= ~MCP51_SMBUS_SETUP_B_TCO_REBOOT;
438 	pci_write_config_dword(tco_pci, MCP51_SMBUS_SETUP_B, val);
439 	pci_read_config_dword(tco_pci, MCP51_SMBUS_SETUP_B, &val);
440 	if (val & MCP51_SMBUS_SETUP_B_TCO_REBOOT) {
441 		pr_crit("Couldn't unset REBOOT bit.  Machine may soon reset\n");
442 	}
443 
444 	/* Deregister */
445 	misc_deregister(&nv_tco_miscdev);
446 	release_region(tcobase, 0x10);
447 }
448 
nv_tco_remove(struct platform_device * dev)449 static void nv_tco_remove(struct platform_device *dev)
450 {
451 	if (tcobase)
452 		nv_tco_cleanup();
453 }
454 
nv_tco_shutdown(struct platform_device * dev)455 static void nv_tco_shutdown(struct platform_device *dev)
456 {
457 	u32 val;
458 
459 	tco_timer_stop();
460 
461 	/* Some BIOSes fail the POST (once) if the NO_REBOOT flag is not
462 	 * unset during shutdown. */
463 	pci_read_config_dword(tco_pci, MCP51_SMBUS_SETUP_B, &val);
464 	val &= ~MCP51_SMBUS_SETUP_B_TCO_REBOOT;
465 	pci_write_config_dword(tco_pci, MCP51_SMBUS_SETUP_B, val);
466 }
467 
468 static struct platform_driver nv_tco_driver = {
469 	.probe		= nv_tco_init,
470 	.remove_new	= nv_tco_remove,
471 	.shutdown	= nv_tco_shutdown,
472 	.driver		= {
473 		.name	= TCO_MODULE_NAME,
474 	},
475 };
476 
nv_tco_init_module(void)477 static int __init nv_tco_init_module(void)
478 {
479 	int err;
480 
481 	pr_info("NV TCO WatchDog Timer Driver v%s\n", TCO_VERSION);
482 
483 	err = platform_driver_register(&nv_tco_driver);
484 	if (err)
485 		return err;
486 
487 	nv_tco_platform_device = platform_device_register_simple(
488 					TCO_MODULE_NAME, -1, NULL, 0);
489 	if (IS_ERR(nv_tco_platform_device)) {
490 		err = PTR_ERR(nv_tco_platform_device);
491 		goto unreg_platform_driver;
492 	}
493 
494 	return 0;
495 
496 unreg_platform_driver:
497 	platform_driver_unregister(&nv_tco_driver);
498 	return err;
499 }
500 
nv_tco_cleanup_module(void)501 static void __exit nv_tco_cleanup_module(void)
502 {
503 	platform_device_unregister(nv_tco_platform_device);
504 	platform_driver_unregister(&nv_tco_driver);
505 	pr_info("NV TCO Watchdog Module Unloaded\n");
506 }
507 
508 module_init(nv_tco_init_module);
509 module_exit(nv_tco_cleanup_module);
510 
511 MODULE_AUTHOR("Mike Waychison");
512 MODULE_DESCRIPTION("TCO timer driver for NV chipsets");
513 MODULE_LICENSE("GPL");
514