1// SPDX-License-Identifier: GPL-2.0+
2/*
3 *	ICP Wafer 5823 Single Board Computer WDT driver
4 *	http://www.icpamerica.com/wafer_5823.php
5 *	May also work on other similar models
6 *
7 *	(c) Copyright 2002 Justin Cormack <justin@street-vision.com>
8 *
9 *	Release 0.02
10 *
11 *	Based on advantechwdt.c which is based on wdt.c.
12 *	Original copyright messages:
13 *
14 *	(c) Copyright 1996-1997 Alan Cox <alan@lxorguk.ukuu.org.uk>,
15 *						All Rights Reserved.
16 *
17 *	Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
18 *	warranty for any of this software. This material is provided
19 *	"AS-IS" and at no charge.
20 *
21 *	(c) Copyright 1995    Alan Cox <alan@lxorguk.ukuu.org.uk>
22 *
23 */
24
25#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
26
27#include <linux/module.h>
28#include <linux/moduleparam.h>
29#include <linux/miscdevice.h>
30#include <linux/watchdog.h>
31#include <linux/fs.h>
32#include <linux/ioport.h>
33#include <linux/notifier.h>
34#include <linux/reboot.h>
35#include <linux/init.h>
36#include <linux/spinlock.h>
37#include <linux/io.h>
38#include <linux/uaccess.h>
39
40#define WATCHDOG_NAME "Wafer 5823 WDT"
41#define PFX WATCHDOG_NAME ": "
42#define WD_TIMO 60			/* 60 sec default timeout */
43
44static unsigned long wafwdt_is_open;
45static char expect_close;
46static DEFINE_SPINLOCK(wafwdt_lock);
47
48/*
49 *	You must set these - there is no sane way to probe for this board.
50 *
51 *	To enable, write the timeout value in seconds (1 to 255) to I/O
52 *	port WDT_START, then read the port to start the watchdog. To pat
53 *	the dog, read port WDT_STOP to stop the timer, then read WDT_START
54 *	to restart it again.
55 */
56
57static int wdt_stop = 0x843;
58static int wdt_start = 0x443;
59
60static int timeout = WD_TIMO;  /* in seconds */
61module_param(timeout, int, 0);
62MODULE_PARM_DESC(timeout,
63		"Watchdog timeout in seconds. 1 <= timeout <= 255, default="
64				__MODULE_STRING(WD_TIMO) ".");
65
66static bool nowayout = WATCHDOG_NOWAYOUT;
67module_param(nowayout, bool, 0);
68MODULE_PARM_DESC(nowayout,
69		"Watchdog cannot be stopped once started (default="
70				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
71
72static void wafwdt_ping(void)
73{
74	/* pat watchdog */
75	spin_lock(&wafwdt_lock);
76	inb_p(wdt_stop);
77	inb_p(wdt_start);
78	spin_unlock(&wafwdt_lock);
79}
80
81static void wafwdt_start(void)
82{
83	/* start up watchdog */
84	outb_p(timeout, wdt_start);
85	inb_p(wdt_start);
86}
87
88static void wafwdt_stop(void)
89{
90	/* stop watchdog */
91	inb_p(wdt_stop);
92}
93
94static ssize_t wafwdt_write(struct file *file, const char __user *buf,
95						size_t count, loff_t *ppos)
96{
97	/* See if we got the magic character 'V' and reload the timer */
98	if (count) {
99		if (!nowayout) {
100			size_t i;
101
102			/* In case it was set long ago */
103			expect_close = 0;
104
105			/* scan to see whether or not we got the magic
106			   character */
107			for (i = 0; i != count; i++) {
108				char c;
109				if (get_user(c, buf + i))
110					return -EFAULT;
111				if (c == 'V')
112					expect_close = 42;
113			}
114		}
115		/* Well, anyhow someone wrote to us, we should
116		   return that favour */
117		wafwdt_ping();
118	}
119	return count;
120}
121
122static long wafwdt_ioctl(struct file *file, unsigned int cmd,
123							unsigned long arg)
124{
125	int new_timeout;
126	void __user *argp = (void __user *)arg;
127	int __user *p = argp;
128	static const struct watchdog_info ident = {
129		.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
130							WDIOF_MAGICCLOSE,
131		.firmware_version = 1,
132		.identity = "Wafer 5823 WDT",
133	};
134
135	switch (cmd) {
136	case WDIOC_GETSUPPORT:
137		if (copy_to_user(argp, &ident, sizeof(ident)))
138			return -EFAULT;
139		break;
140
141	case WDIOC_GETSTATUS:
142	case WDIOC_GETBOOTSTATUS:
143		return put_user(0, p);
144
145	case WDIOC_SETOPTIONS:
146	{
147		int options, retval = -EINVAL;
148
149		if (get_user(options, p))
150			return -EFAULT;
151
152		if (options & WDIOS_DISABLECARD) {
153			wafwdt_stop();
154			retval = 0;
155		}
156
157		if (options & WDIOS_ENABLECARD) {
158			wafwdt_start();
159			retval = 0;
160		}
161
162		return retval;
163	}
164
165	case WDIOC_KEEPALIVE:
166		wafwdt_ping();
167		break;
168
169	case WDIOC_SETTIMEOUT:
170		if (get_user(new_timeout, p))
171			return -EFAULT;
172		if ((new_timeout < 1) || (new_timeout > 255))
173			return -EINVAL;
174		timeout = new_timeout;
175		wafwdt_stop();
176		wafwdt_start();
177		fallthrough;
178	case WDIOC_GETTIMEOUT:
179		return put_user(timeout, p);
180
181	default:
182		return -ENOTTY;
183	}
184	return 0;
185}
186
187static int wafwdt_open(struct inode *inode, struct file *file)
188{
189	if (test_and_set_bit(0, &wafwdt_is_open))
190		return -EBUSY;
191
192	/*
193	 *      Activate
194	 */
195	wafwdt_start();
196	return stream_open(inode, file);
197}
198
199static int wafwdt_close(struct inode *inode, struct file *file)
200{
201	if (expect_close == 42)
202		wafwdt_stop();
203	else {
204		pr_crit("WDT device closed unexpectedly.  WDT will not stop!\n");
205		wafwdt_ping();
206	}
207	clear_bit(0, &wafwdt_is_open);
208	expect_close = 0;
209	return 0;
210}
211
212/*
213 *	Notifier for system down
214 */
215
216static int wafwdt_notify_sys(struct notifier_block *this, unsigned long code,
217								void *unused)
218{
219	if (code == SYS_DOWN || code == SYS_HALT)
220		wafwdt_stop();
221	return NOTIFY_DONE;
222}
223
224/*
225 *	Kernel Interfaces
226 */
227
228static const struct file_operations wafwdt_fops = {
229	.owner		= THIS_MODULE,
230	.llseek		= no_llseek,
231	.write		= wafwdt_write,
232	.unlocked_ioctl	= wafwdt_ioctl,
233	.compat_ioctl	= compat_ptr_ioctl,
234	.open		= wafwdt_open,
235	.release	= wafwdt_close,
236};
237
238static struct miscdevice wafwdt_miscdev = {
239	.minor	= WATCHDOG_MINOR,
240	.name	= "watchdog",
241	.fops	= &wafwdt_fops,
242};
243
244/*
245 *	The WDT needs to learn about soft shutdowns in order to
246 *	turn the timebomb registers off.
247 */
248
249static struct notifier_block wafwdt_notifier = {
250	.notifier_call = wafwdt_notify_sys,
251};
252
253static int __init wafwdt_init(void)
254{
255	int ret;
256
257	pr_info("WDT driver for Wafer 5823 single board computer initialising\n");
258
259	if (timeout < 1 || timeout > 255) {
260		timeout = WD_TIMO;
261		pr_info("timeout value must be 1 <= x <= 255, using %d\n",
262			timeout);
263	}
264
265	if (wdt_stop != wdt_start) {
266		if (!request_region(wdt_stop, 1, "Wafer 5823 WDT")) {
267			pr_err("I/O address 0x%04x already in use\n", wdt_stop);
268			ret = -EIO;
269			goto error;
270		}
271	}
272
273	if (!request_region(wdt_start, 1, "Wafer 5823 WDT")) {
274		pr_err("I/O address 0x%04x already in use\n", wdt_start);
275		ret = -EIO;
276		goto error2;
277	}
278
279	ret = register_reboot_notifier(&wafwdt_notifier);
280	if (ret != 0) {
281		pr_err("cannot register reboot notifier (err=%d)\n", ret);
282		goto error3;
283	}
284
285	ret = misc_register(&wafwdt_miscdev);
286	if (ret != 0) {
287		pr_err("cannot register miscdev on minor=%d (err=%d)\n",
288		       WATCHDOG_MINOR, ret);
289		goto error4;
290	}
291
292	pr_info("initialized. timeout=%d sec (nowayout=%d)\n",
293		timeout, nowayout);
294
295	return ret;
296error4:
297	unregister_reboot_notifier(&wafwdt_notifier);
298error3:
299	release_region(wdt_start, 1);
300error2:
301	if (wdt_stop != wdt_start)
302		release_region(wdt_stop, 1);
303error:
304	return ret;
305}
306
307static void __exit wafwdt_exit(void)
308{
309	misc_deregister(&wafwdt_miscdev);
310	unregister_reboot_notifier(&wafwdt_notifier);
311	if (wdt_stop != wdt_start)
312		release_region(wdt_stop, 1);
313	release_region(wdt_start, 1);
314}
315
316module_init(wafwdt_init);
317module_exit(wafwdt_exit);
318
319MODULE_AUTHOR("Justin Cormack");
320MODULE_DESCRIPTION("ICP Wafer 5823 Single Board Computer WDT driver");
321MODULE_LICENSE("GPL");
322
323/* end of wafer5823wdt.c */
324