1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 *	ALi M7101 PMU Computer Watchdog Timer driver
4 *
5 *	Based on w83877f_wdt.c by Scott Jennings <linuxdrivers@oro.net>
6 *	and the Cobalt kernel WDT timer driver by Tim Hockin
7 *	                                      <thockin@cobaltnet.com>
8 *
9 *	(c)2002 Steve Hill <steve@navaho.co.uk>
10 *
11 *  This WDT driver is different from most other Linux WDT
12 *  drivers in that the driver will ping the watchdog by itself,
13 *  because this particular WDT has a very short timeout (1.6
14 *  seconds) and it would be insane to count on any userspace
15 *  daemon always getting scheduled within that time frame.
16 *
17 *  Additions:
18 *   Aug 23, 2004 - Added use_gpio module parameter for use on revision a1d PMUs
19 *                  found on very old cobalt hardware.
20 *                  -- Mike Waychison <michael.waychison@sun.com>
21 */
22
23#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
24
25#include <linux/module.h>
26#include <linux/moduleparam.h>
27#include <linux/types.h>
28#include <linux/timer.h>
29#include <linux/miscdevice.h>
30#include <linux/watchdog.h>
31#include <linux/ioport.h>
32#include <linux/notifier.h>
33#include <linux/reboot.h>
34#include <linux/init.h>
35#include <linux/fs.h>
36#include <linux/pci.h>
37#include <linux/io.h>
38#include <linux/uaccess.h>
39
40
41#define WDT_ENABLE 0x9C
42#define WDT_DISABLE 0x8C
43
44#define ALI_7101_WDT    0x92
45#define ALI_7101_GPIO   0x7D
46#define ALI_7101_GPIO_O 0x7E
47#define ALI_WDT_ARM     0x01
48
49/*
50 * We're going to use a 1 second timeout.
51 * If we reset the watchdog every ~250ms we should be safe.  */
52
53#define WDT_INTERVAL (HZ/4+1)
54
55/*
56 * We must not require too good response from the userspace daemon.
57 * Here we require the userspace daemon to send us a heartbeat
58 * char to /dev/watchdog every 30 seconds.
59 */
60
61#define WATCHDOG_TIMEOUT 30            /* 30 sec default timeout */
62/* in seconds, will be multiplied by HZ to get seconds to wait for a ping */
63static int timeout = WATCHDOG_TIMEOUT;
64module_param(timeout, int, 0);
65MODULE_PARM_DESC(timeout,
66		"Watchdog timeout in seconds. (1<=timeout<=3600, default="
67				__MODULE_STRING(WATCHDOG_TIMEOUT) ")");
68
69static int use_gpio; /* Use the pic (for a1d revision alim7101) */
70module_param(use_gpio, int, 0);
71MODULE_PARM_DESC(use_gpio,
72		"Use the gpio watchdog (required by old cobalt boards).");
73
74static void wdt_timer_ping(struct timer_list *);
75static DEFINE_TIMER(timer, wdt_timer_ping);
76static unsigned long next_heartbeat;
77static unsigned long wdt_is_open;
78static char wdt_expect_close;
79static struct pci_dev *alim7101_pmu;
80
81static bool nowayout = WATCHDOG_NOWAYOUT;
82module_param(nowayout, bool, 0);
83MODULE_PARM_DESC(nowayout,
84		"Watchdog cannot be stopped once started (default="
85				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
86
87/*
88 *	Whack the dog
89 */
90
91static void wdt_timer_ping(struct timer_list *unused)
92{
93	/* If we got a heartbeat pulse within the WDT_US_INTERVAL
94	 * we agree to ping the WDT
95	 */
96	char tmp;
97
98	if (time_before(jiffies, next_heartbeat)) {
99		/* Ping the WDT (this is actually a disarm/arm sequence) */
100		pci_read_config_byte(alim7101_pmu, 0x92, &tmp);
101		pci_write_config_byte(alim7101_pmu,
102					ALI_7101_WDT, (tmp & ~ALI_WDT_ARM));
103		pci_write_config_byte(alim7101_pmu,
104					ALI_7101_WDT, (tmp | ALI_WDT_ARM));
105		if (use_gpio) {
106			pci_read_config_byte(alim7101_pmu,
107					ALI_7101_GPIO_O, &tmp);
108			pci_write_config_byte(alim7101_pmu,
109					ALI_7101_GPIO_O, tmp | 0x20);
110			pci_write_config_byte(alim7101_pmu,
111					ALI_7101_GPIO_O, tmp & ~0x20);
112		}
113	} else {
114		pr_warn("Heartbeat lost! Will not ping the watchdog\n");
115	}
116	/* Re-set the timer interval */
117	mod_timer(&timer, jiffies + WDT_INTERVAL);
118}
119
120/*
121 * Utility routines
122 */
123
124static void wdt_change(int writeval)
125{
126	char tmp;
127
128	pci_read_config_byte(alim7101_pmu, ALI_7101_WDT, &tmp);
129	if (writeval == WDT_ENABLE) {
130		pci_write_config_byte(alim7101_pmu,
131					ALI_7101_WDT, (tmp | ALI_WDT_ARM));
132		if (use_gpio) {
133			pci_read_config_byte(alim7101_pmu,
134					ALI_7101_GPIO_O, &tmp);
135			pci_write_config_byte(alim7101_pmu,
136					ALI_7101_GPIO_O, tmp & ~0x20);
137		}
138
139	} else {
140		pci_write_config_byte(alim7101_pmu,
141					ALI_7101_WDT, (tmp & ~ALI_WDT_ARM));
142		if (use_gpio) {
143			pci_read_config_byte(alim7101_pmu,
144					ALI_7101_GPIO_O, &tmp);
145			pci_write_config_byte(alim7101_pmu,
146					ALI_7101_GPIO_O, tmp | 0x20);
147		}
148	}
149}
150
151static void wdt_startup(void)
152{
153	next_heartbeat = jiffies + (timeout * HZ);
154
155	/* We must enable before we kick off the timer in case the timer
156	   occurs as we ping it */
157
158	wdt_change(WDT_ENABLE);
159
160	/* Start the timer */
161	mod_timer(&timer, jiffies + WDT_INTERVAL);
162
163	pr_info("Watchdog timer is now enabled\n");
164}
165
166static void wdt_turnoff(void)
167{
168	/* Stop the timer */
169	del_timer_sync(&timer);
170	wdt_change(WDT_DISABLE);
171	pr_info("Watchdog timer is now disabled...\n");
172}
173
174static void wdt_keepalive(void)
175{
176	/* user land ping */
177	next_heartbeat = jiffies + (timeout * HZ);
178}
179
180/*
181 * /dev/watchdog handling
182 */
183
184static ssize_t fop_write(struct file *file, const char __user *buf,
185						size_t count, loff_t *ppos)
186{
187	/* See if we got the magic character 'V' and reload the timer */
188	if (count) {
189		if (!nowayout) {
190			size_t ofs;
191
192			/* note: just in case someone wrote the magic character
193			 * five months ago... */
194			wdt_expect_close = 0;
195
196			/* now scan */
197			for (ofs = 0; ofs != count; ofs++) {
198				char c;
199				if (get_user(c, buf + ofs))
200					return -EFAULT;
201				if (c == 'V')
202					wdt_expect_close = 42;
203			}
204		}
205		/* someone wrote to us, we should restart timer */
206		wdt_keepalive();
207	}
208	return count;
209}
210
211static int fop_open(struct inode *inode, struct file *file)
212{
213	/* Just in case we're already talking to someone... */
214	if (test_and_set_bit(0, &wdt_is_open))
215		return -EBUSY;
216	/* Good, fire up the show */
217	wdt_startup();
218	return stream_open(inode, file);
219}
220
221static int fop_close(struct inode *inode, struct file *file)
222{
223	if (wdt_expect_close == 42)
224		wdt_turnoff();
225	else {
226		/* wim: shouldn't there be a: del_timer(&timer); */
227		pr_crit("device file closed unexpectedly. Will not stop the WDT!\n");
228	}
229	clear_bit(0, &wdt_is_open);
230	wdt_expect_close = 0;
231	return 0;
232}
233
234static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
235{
236	void __user *argp = (void __user *)arg;
237	int __user *p = argp;
238	static const struct watchdog_info ident = {
239		.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT
240							| WDIOF_MAGICCLOSE,
241		.firmware_version = 1,
242		.identity = "ALiM7101",
243	};
244
245	switch (cmd) {
246	case WDIOC_GETSUPPORT:
247		return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
248	case WDIOC_GETSTATUS:
249	case WDIOC_GETBOOTSTATUS:
250		return put_user(0, p);
251	case WDIOC_SETOPTIONS:
252	{
253		int new_options, retval = -EINVAL;
254
255		if (get_user(new_options, p))
256			return -EFAULT;
257		if (new_options & WDIOS_DISABLECARD) {
258			wdt_turnoff();
259			retval = 0;
260		}
261		if (new_options & WDIOS_ENABLECARD) {
262			wdt_startup();
263			retval = 0;
264		}
265		return retval;
266	}
267	case WDIOC_KEEPALIVE:
268		wdt_keepalive();
269		return 0;
270	case WDIOC_SETTIMEOUT:
271	{
272		int new_timeout;
273
274		if (get_user(new_timeout, p))
275			return -EFAULT;
276		/* arbitrary upper limit */
277		if (new_timeout < 1 || new_timeout > 3600)
278			return -EINVAL;
279		timeout = new_timeout;
280		wdt_keepalive();
281	}
282		fallthrough;
283	case WDIOC_GETTIMEOUT:
284		return put_user(timeout, p);
285	default:
286		return -ENOTTY;
287	}
288}
289
290static const struct file_operations wdt_fops = {
291	.owner		=	THIS_MODULE,
292	.llseek		=	no_llseek,
293	.write		=	fop_write,
294	.open		=	fop_open,
295	.release	=	fop_close,
296	.unlocked_ioctl	=	fop_ioctl,
297	.compat_ioctl	= 	compat_ptr_ioctl,
298};
299
300static struct miscdevice wdt_miscdev = {
301	.minor	=	WATCHDOG_MINOR,
302	.name	=	"watchdog",
303	.fops	=	&wdt_fops,
304};
305
306static int wdt_restart_handle(struct notifier_block *this, unsigned long mode,
307			      void *cmd)
308{
309	/*
310	 * Cobalt devices have no way of rebooting themselves other
311	 * than getting the watchdog to pull reset, so we restart the
312	 * watchdog on reboot with no heartbeat.
313	 */
314	wdt_change(WDT_ENABLE);
315
316	/* loop until the watchdog fires */
317	while (true)
318		;
319
320	return NOTIFY_DONE;
321}
322
323static struct notifier_block wdt_restart_handler = {
324	.notifier_call = wdt_restart_handle,
325	.priority = 128,
326};
327
328/*
329 *	Notifier for system down
330 */
331
332static int wdt_notify_sys(struct notifier_block *this,
333					unsigned long code, void *unused)
334{
335	if (code == SYS_DOWN || code == SYS_HALT)
336		wdt_turnoff();
337
338	return NOTIFY_DONE;
339}
340
341/*
342 *	The WDT needs to learn about soft shutdowns in order to
343 *	turn the timebomb registers off.
344 */
345
346static struct notifier_block wdt_notifier = {
347	.notifier_call = wdt_notify_sys,
348};
349
350static void __exit alim7101_wdt_unload(void)
351{
352	wdt_turnoff();
353	/* Deregister */
354	misc_deregister(&wdt_miscdev);
355	unregister_reboot_notifier(&wdt_notifier);
356	unregister_restart_handler(&wdt_restart_handler);
357	pci_dev_put(alim7101_pmu);
358}
359
360static int __init alim7101_wdt_init(void)
361{
362	int rc = -EBUSY;
363	struct pci_dev *ali1543_south;
364	char tmp;
365
366	pr_info("Steve Hill <steve@navaho.co.uk>\n");
367	alim7101_pmu = pci_get_device(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M7101,
368		NULL);
369	if (!alim7101_pmu) {
370		pr_info("ALi M7101 PMU not present - WDT not set\n");
371		return -EBUSY;
372	}
373
374	/* Set the WDT in the PMU to 1 second */
375	pci_write_config_byte(alim7101_pmu, ALI_7101_WDT, 0x02);
376
377	ali1543_south = pci_get_device(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M1533,
378		NULL);
379	if (!ali1543_south) {
380		pr_info("ALi 1543 South-Bridge not present - WDT not set\n");
381		goto err_out;
382	}
383	pci_read_config_byte(ali1543_south, 0x5e, &tmp);
384	pci_dev_put(ali1543_south);
385	if ((tmp & 0x1e) == 0x00) {
386		if (!use_gpio) {
387			pr_info("Detected old alim7101 revision 'a1d'.  If this is a cobalt board, set the 'use_gpio' module parameter.\n");
388			goto err_out;
389		}
390		nowayout = 1;
391	} else if ((tmp & 0x1e) != 0x12 && (tmp & 0x1e) != 0x00) {
392		pr_info("ALi 1543 South-Bridge does not have the correct revision number (???1001?) - WDT not set\n");
393		goto err_out;
394	}
395
396	if (timeout < 1 || timeout > 3600) {
397		/* arbitrary upper limit */
398		timeout = WATCHDOG_TIMEOUT;
399		pr_info("timeout value must be 1 <= x <= 3600, using %d\n",
400			timeout);
401	}
402
403	rc = register_reboot_notifier(&wdt_notifier);
404	if (rc) {
405		pr_err("cannot register reboot notifier (err=%d)\n", rc);
406		goto err_out;
407	}
408
409	rc = register_restart_handler(&wdt_restart_handler);
410	if (rc) {
411		pr_err("cannot register restart handler (err=%d)\n", rc);
412		goto err_out_reboot;
413	}
414
415	rc = misc_register(&wdt_miscdev);
416	if (rc) {
417		pr_err("cannot register miscdev on minor=%d (err=%d)\n",
418		       wdt_miscdev.minor, rc);
419		goto err_out_restart;
420	}
421
422	if (nowayout)
423		__module_get(THIS_MODULE);
424
425	pr_info("WDT driver for ALi M7101 initialised. timeout=%d sec (nowayout=%d)\n",
426		timeout, nowayout);
427	return 0;
428
429err_out_restart:
430	unregister_restart_handler(&wdt_restart_handler);
431err_out_reboot:
432	unregister_reboot_notifier(&wdt_notifier);
433err_out:
434	pci_dev_put(alim7101_pmu);
435	return rc;
436}
437
438module_init(alim7101_wdt_init);
439module_exit(alim7101_wdt_unload);
440
441static const struct pci_device_id alim7101_pci_tbl[] __used = {
442	{ PCI_DEVICE(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M1533) },
443	{ PCI_DEVICE(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M7101) },
444	{ }
445};
446
447MODULE_DEVICE_TABLE(pci, alim7101_pci_tbl);
448
449MODULE_AUTHOR("Steve Hill");
450MODULE_DESCRIPTION("ALi M7101 PMU Computer Watchdog Timer driver");
451MODULE_LICENSE("GPL");
452