nv_tco.c

  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 */
 44static unsigned int tcobase;
 45static DEFINE_SPINLOCK(tco_lock);	/* Guards the hardware */
 46static unsigned long timer_alive;
 47static char tco_expect_close;
 48static struct pci_dev *tco_pci;
 49
 50/* the watchdog platform device */
 51static struct platform_device *nv_tco_platform_device;
 52
 53/* module parameters */
 54#define WATCHDOG_HEARTBEAT 30	/* 30 sec default heartbeat (2<heartbeat<39) */
 55static int heartbeat = WATCHDOG_HEARTBEAT;  /* in seconds */
 56module_param(heartbeat, int, 0);
 57MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds. (2<heartbeat<39, "
 58			    "default=" __MODULE_STRING(WATCHDOG_HEARTBEAT) ")");
 59
 60static bool nowayout = WATCHDOG_NOWAYOUT;
 61module_param(nowayout, bool, 0);
 62MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started"
 63		" (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 64
 65/*
 66 * Some TCO specific functions
 67 */
 68static 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
 75static 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
 87static 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
 99static 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
108static 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
151static 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
163static 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
177static 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
210static 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
265static const struct file_operations nv_tco_fops = {
266	.owner =		THIS_MODULE,
267	.write =		nv_tco_write,
268	.unlocked_ioctl =	nv_tco_ioctl,
269	.compat_ioctl =		compat_ptr_ioctl,
270	.open =			nv_tco_open,
271	.release =		nv_tco_release,
272};
273
274static struct miscdevice nv_tco_miscdev = {
275	.minor =	WATCHDOG_MINOR,
276	.name =		"watchdog",
277	.fops =		&nv_tco_fops,
278};
279
280/*
281 * Data for PCI driver interface
282 *
283 * This data only exists for exporting the supported
284 * PCI ids via MODULE_DEVICE_TABLE.  We do not actually
285 * register a pci_driver, because someone else might one day
286 * want to register another driver on the same PCI id.
287 */
288static const struct pci_device_id tco_pci_tbl[] = {
289	{ PCI_VENDOR_ID_NVIDIA, PCI_DEVICE_ID_NVIDIA_NFORCE_MCP51_SMBUS,
290	  PCI_ANY_ID, PCI_ANY_ID, },
291	{ PCI_VENDOR_ID_NVIDIA, PCI_DEVICE_ID_NVIDIA_NFORCE_MCP55_SMBUS,
292	  PCI_ANY_ID, PCI_ANY_ID, },
293	{ PCI_VENDOR_ID_NVIDIA, PCI_DEVICE_ID_NVIDIA_NFORCE_MCP78S_SMBUS,
294	  PCI_ANY_ID, PCI_ANY_ID, },
295	{ PCI_VENDOR_ID_NVIDIA, PCI_DEVICE_ID_NVIDIA_NFORCE_MCP79_SMBUS,
296	  PCI_ANY_ID, PCI_ANY_ID, },
297	{ 0, },			/* End of list */
298};
299MODULE_DEVICE_TABLE(pci, tco_pci_tbl);
300
301/*
302 *	Init & exit routines
303 */
304
305static unsigned char nv_tco_getdevice(void)
306{
307	struct pci_dev *dev = NULL;
308	u32 val;
309
310	/* Find the PCI device */
311	for_each_pci_dev(dev) {
312		if (pci_match_id(tco_pci_tbl, dev) != NULL) {
313			tco_pci = dev;
314			break;
315		}
316	}
317
318	if (!tco_pci)
319		return 0;
320
321	/* Find the base io port */
322	pci_read_config_dword(tco_pci, 0x64, &val);
323	val &= 0xffff;
324	if (val == 0x0001 || val == 0x0000) {
325		/* Something is wrong here, bar isn't setup */
326		pr_err("failed to get tcobase address\n");
327		return 0;
328	}
329	val &= 0xff00;
330	tcobase = val + 0x40;
331
332	if (!request_region(tcobase, 0x10, "NV TCO")) {
333		pr_err("I/O address 0x%04x already in use\n", tcobase);
334		return 0;
335	}
336
337	/* Set a reasonable heartbeat before we stop the timer */
338	tco_timer_set_heartbeat(30);
339
340	/*
341	 * Stop the TCO before we change anything so we don't race with
342	 * a zeroed timer.
343	 */
344	tco_timer_keepalive();
345	tco_timer_stop();
346
347	/* Disable SMI caused by TCO */
348	if (!request_region(MCP51_SMI_EN(tcobase), 4, "NV TCO")) {
349		pr_err("I/O address 0x%04x already in use\n",
350		       MCP51_SMI_EN(tcobase));
351		goto out;
352	}
353	val = inl(MCP51_SMI_EN(tcobase));
354	val &= ~MCP51_SMI_EN_TCO;
355	outl(val, MCP51_SMI_EN(tcobase));
356	val = inl(MCP51_SMI_EN(tcobase));
357	release_region(MCP51_SMI_EN(tcobase), 4);
358	if (val & MCP51_SMI_EN_TCO) {
359		pr_err("Could not disable SMI caused by TCO\n");
360		goto out;
361	}
362
363	/* Check chipset's NO_REBOOT bit */
364	pci_read_config_dword(tco_pci, MCP51_SMBUS_SETUP_B, &val);
365	val |= MCP51_SMBUS_SETUP_B_TCO_REBOOT;
366	pci_write_config_dword(tco_pci, MCP51_SMBUS_SETUP_B, val);
367	pci_read_config_dword(tco_pci, MCP51_SMBUS_SETUP_B, &val);
368	if (!(val & MCP51_SMBUS_SETUP_B_TCO_REBOOT)) {
369		pr_err("failed to reset NO_REBOOT flag, reboot disabled by hardware\n");
370		goto out;
371	}
372
373	return 1;
374out:
375	release_region(tcobase, 0x10);
376	return 0;
377}
378
379static int nv_tco_init(struct platform_device *dev)
380{
381	int ret;
382
383	/* Check whether or not the hardware watchdog is there */
384	if (!nv_tco_getdevice())
385		return -ENODEV;
386
387	/* Check to see if last reboot was due to watchdog timeout */
388	pr_info("Watchdog reboot %sdetected\n",
389		inl(TCO_STS(tcobase)) & TCO_STS_TCO2TO_STS ? "" : "not ");
390
391	/* Clear out the old status */
392	outl(TCO_STS_RESET, TCO_STS(tcobase));
393
394	/*
395	 * Check that the heartbeat value is within it's range.
396	 * If not, reset to the default.
397	 */
398	if (tco_timer_set_heartbeat(heartbeat)) {
399		heartbeat = WATCHDOG_HEARTBEAT;
400		tco_timer_set_heartbeat(heartbeat);
401		pr_info("heartbeat value must be 2<heartbeat<39, using %d\n",
402			heartbeat);
403	}
404
405	ret = misc_register(&nv_tco_miscdev);
406	if (ret != 0) {
407		pr_err("cannot register miscdev on minor=%d (err=%d)\n",
408		       WATCHDOG_MINOR, ret);
409		goto unreg_region;
410	}
411
412	clear_bit(0, &timer_alive);
413
414	tco_timer_stop();
415
416	pr_info("initialized (0x%04x). heartbeat=%d sec (nowayout=%d)\n",
417		tcobase, heartbeat, nowayout);
418
419	return 0;
420
421unreg_region:
422	release_region(tcobase, 0x10);
423	return ret;
424}
425
426static void nv_tco_cleanup(void)
427{
428	u32 val;
429
430	/* Stop the timer before we leave */
431	if (!nowayout)
432		tco_timer_stop();
433
434	/* Set the NO_REBOOT bit to prevent later reboots, just for sure */
435	pci_read_config_dword(tco_pci, MCP51_SMBUS_SETUP_B, &val);
436	val &= ~MCP51_SMBUS_SETUP_B_TCO_REBOOT;
437	pci_write_config_dword(tco_pci, MCP51_SMBUS_SETUP_B, val);
438	pci_read_config_dword(tco_pci, MCP51_SMBUS_SETUP_B, &val);
439	if (val & MCP51_SMBUS_SETUP_B_TCO_REBOOT) {
440		pr_crit("Couldn't unset REBOOT bit.  Machine may soon reset\n");
441	}
442
443	/* Deregister */
444	misc_deregister(&nv_tco_miscdev);
445	release_region(tcobase, 0x10);
446}
447
448static void nv_tco_remove(struct platform_device *dev)
449{
450	if (tcobase)
451		nv_tco_cleanup();
452}
453
454static void nv_tco_shutdown(struct platform_device *dev)
455{
456	u32 val;
457
458	tco_timer_stop();
459
460	/* Some BIOSes fail the POST (once) if the NO_REBOOT flag is not
461	 * unset during shutdown. */
462	pci_read_config_dword(tco_pci, MCP51_SMBUS_SETUP_B, &val);
463	val &= ~MCP51_SMBUS_SETUP_B_TCO_REBOOT;
464	pci_write_config_dword(tco_pci, MCP51_SMBUS_SETUP_B, val);
465}
466
467static struct platform_driver nv_tco_driver = {
468	.probe		= nv_tco_init,
469	.remove		= nv_tco_remove,
470	.shutdown	= nv_tco_shutdown,
471	.driver		= {
472		.name	= TCO_MODULE_NAME,
473	},
474};
475
476static int __init nv_tco_init_module(void)
477{
478	int err;
479
480	pr_info("NV TCO WatchDog Timer Driver v%s\n", TCO_VERSION);
481
482	err = platform_driver_register(&nv_tco_driver);
483	if (err)
484		return err;
485
486	nv_tco_platform_device = platform_device_register_simple(
487					TCO_MODULE_NAME, -1, NULL, 0);
488	if (IS_ERR(nv_tco_platform_device)) {
489		err = PTR_ERR(nv_tco_platform_device);
490		goto unreg_platform_driver;
491	}
492
493	return 0;
494
495unreg_platform_driver:
496	platform_driver_unregister(&nv_tco_driver);
497	return err;
498}
499
500static void __exit nv_tco_cleanup_module(void)
501{
502	platform_device_unregister(nv_tco_platform_device);
503	platform_driver_unregister(&nv_tco_driver);
504	pr_info("NV TCO Watchdog Module Unloaded\n");
505}
506
507module_init(nv_tco_init_module);
508module_exit(nv_tco_cleanup_module);
509
510MODULE_AUTHOR("Mike Waychison");
511MODULE_DESCRIPTION("TCO timer driver for NV chipsets");
512MODULE_LICENSE("GPL");