1// SPDX-License-Identifier: GPL-2.0+
2/*
3 *	Advantech Single Board Computer WDT driver
4 *
5 *	(c) Copyright 2000-2001 Marek Michalkiewicz <marekm@linux.org.pl>
6 *
7 *	Based on acquirewdt.c which is based on wdt.c.
8 *	Original copyright messages:
9 *
10 *	(c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
11 *						All Rights Reserved.
12 *
13 *	Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
14 *	warranty for any of this software. This material is provided
15 *	"AS-IS" and at no charge.
16 *
17 *	(c) Copyright 1995    Alan Cox <alan@lxorguk.ukuu.org.uk>
18 *
19 *	14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
20 *	    Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
21 *
22 *	16-Oct-2002 Rob Radez <rob@osinvestor.com>
23 *	    Clean up ioctls, clean up init + exit, add expect close support,
24 *	    add wdt_start and wdt_stop as parameters.
25 */
26
27#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
28
29#include <linux/module.h>
30#include <linux/moduleparam.h>
31#include <linux/types.h>
32#include <linux/miscdevice.h>
33#include <linux/watchdog.h>
34#include <linux/fs.h>
35#include <linux/ioport.h>
36#include <linux/platform_device.h>
37#include <linux/init.h>
38#include <linux/io.h>
39#include <linux/uaccess.h>
40
41
42#define DRV_NAME "advantechwdt"
43#define WATCHDOG_NAME "Advantech WDT"
44#define WATCHDOG_TIMEOUT 60		/* 60 sec default timeout */
45
46/* the watchdog platform device */
47static struct platform_device *advwdt_platform_device;
48static unsigned long advwdt_is_open;
49static char adv_expect_close;
50
51/*
52 *	You must set these - there is no sane way to probe for this board.
53 *
54 *	To enable or restart, write the timeout value in seconds (1 to 63)
55 *	to I/O port wdt_start.  To disable, read I/O port wdt_stop.
56 *	Both are 0x443 for most boards (tested on a PCA-6276VE-00B1), but
57 *	check your manual (at least the PCA-6159 seems to be different -
58 *	the manual says wdt_stop is 0x43, not 0x443).
59 *	(0x43 is also a write-only control register for the 8254 timer!)
60 */
61
62static int wdt_stop = 0x443;
63module_param(wdt_stop, int, 0);
64MODULE_PARM_DESC(wdt_stop, "Advantech WDT 'stop' io port (default 0x443)");
65
66static int wdt_start = 0x443;
67module_param(wdt_start, int, 0);
68MODULE_PARM_DESC(wdt_start, "Advantech WDT 'start' io port (default 0x443)");
69
70static int timeout = WATCHDOG_TIMEOUT;	/* in seconds */
71module_param(timeout, int, 0);
72MODULE_PARM_DESC(timeout,
73	"Watchdog timeout in seconds. 1<= timeout <=63, default="
74		__MODULE_STRING(WATCHDOG_TIMEOUT) ".");
75
76static bool nowayout = WATCHDOG_NOWAYOUT;
77module_param(nowayout, bool, 0);
78MODULE_PARM_DESC(nowayout,
79	"Watchdog cannot be stopped once started (default="
80		__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
81
82/*
83 *	Watchdog Operations
84 */
85
86static void advwdt_ping(void)
87{
88	/* Write a watchdog value */
89	outb_p(timeout, wdt_start);
90}
91
92static void advwdt_disable(void)
93{
94	inb_p(wdt_stop);
95}
96
97static int advwdt_set_heartbeat(int t)
98{
99	if (t < 1 || t > 63)
100		return -EINVAL;
101	timeout = t;
102	return 0;
103}
104
105/*
106 *	/dev/watchdog handling
107 */
108
109static ssize_t advwdt_write(struct file *file, const char __user *buf,
110						size_t count, loff_t *ppos)
111{
112	if (count) {
113		if (!nowayout) {
114			size_t i;
115
116			adv_expect_close = 0;
117
118			for (i = 0; i != count; i++) {
119				char c;
120				if (get_user(c, buf + i))
121					return -EFAULT;
122				if (c == 'V')
123					adv_expect_close = 42;
124			}
125		}
126		advwdt_ping();
127	}
128	return count;
129}
130
131static long advwdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
132{
133	int new_timeout;
134	void __user *argp = (void __user *)arg;
135	int __user *p = argp;
136	static const struct watchdog_info ident = {
137		.options = WDIOF_KEEPALIVEPING |
138			   WDIOF_SETTIMEOUT |
139			   WDIOF_MAGICCLOSE,
140		.firmware_version = 1,
141		.identity = WATCHDOG_NAME,
142	};
143
144	switch (cmd) {
145	case WDIOC_GETSUPPORT:
146		if (copy_to_user(argp, &ident, sizeof(ident)))
147			return -EFAULT;
148		break;
149
150	case WDIOC_GETSTATUS:
151	case WDIOC_GETBOOTSTATUS:
152		return put_user(0, p);
153
154	case WDIOC_SETOPTIONS:
155	{
156		int options, retval = -EINVAL;
157
158		if (get_user(options, p))
159			return -EFAULT;
160		if (options & WDIOS_DISABLECARD) {
161			advwdt_disable();
162			retval = 0;
163		}
164		if (options & WDIOS_ENABLECARD) {
165			advwdt_ping();
166			retval = 0;
167		}
168		return retval;
169	}
170	case WDIOC_KEEPALIVE:
171		advwdt_ping();
172		break;
173
174	case WDIOC_SETTIMEOUT:
175		if (get_user(new_timeout, p))
176			return -EFAULT;
177		if (advwdt_set_heartbeat(new_timeout))
178			return -EINVAL;
179		advwdt_ping();
180		fallthrough;
181	case WDIOC_GETTIMEOUT:
182		return put_user(timeout, p);
183	default:
184		return -ENOTTY;
185	}
186	return 0;
187}
188
189static int advwdt_open(struct inode *inode, struct file *file)
190{
191	if (test_and_set_bit(0, &advwdt_is_open))
192		return -EBUSY;
193	/*
194	 *	Activate
195	 */
196
197	advwdt_ping();
198	return stream_open(inode, file);
199}
200
201static int advwdt_close(struct inode *inode, struct file *file)
202{
203	if (adv_expect_close == 42) {
204		advwdt_disable();
205	} else {
206		pr_crit("Unexpected close, not stopping watchdog!\n");
207		advwdt_ping();
208	}
209	clear_bit(0, &advwdt_is_open);
210	adv_expect_close = 0;
211	return 0;
212}
213
214/*
215 *	Kernel Interfaces
216 */
217
218static const struct file_operations advwdt_fops = {
219	.owner		= THIS_MODULE,
220	.llseek		= no_llseek,
221	.write		= advwdt_write,
222	.unlocked_ioctl	= advwdt_ioctl,
223	.compat_ioctl	= compat_ptr_ioctl,
224	.open		= advwdt_open,
225	.release	= advwdt_close,
226};
227
228static struct miscdevice advwdt_miscdev = {
229	.minor	= WATCHDOG_MINOR,
230	.name	= "watchdog",
231	.fops	= &advwdt_fops,
232};
233
234/*
235 *	Init & exit routines
236 */
237
238static int __init advwdt_probe(struct platform_device *dev)
239{
240	int ret;
241
242	if (wdt_stop != wdt_start) {
243		if (!request_region(wdt_stop, 1, WATCHDOG_NAME)) {
244			pr_err("I/O address 0x%04x already in use\n",
245			       wdt_stop);
246			ret = -EIO;
247			goto out;
248		}
249	}
250
251	if (!request_region(wdt_start, 1, WATCHDOG_NAME)) {
252		pr_err("I/O address 0x%04x already in use\n", wdt_start);
253		ret = -EIO;
254		goto unreg_stop;
255	}
256
257	/* Check that the heartbeat value is within it's range ;
258	 * if not reset to the default */
259	if (advwdt_set_heartbeat(timeout)) {
260		advwdt_set_heartbeat(WATCHDOG_TIMEOUT);
261		pr_info("timeout value must be 1<=x<=63, using %d\n", timeout);
262	}
263
264	ret = misc_register(&advwdt_miscdev);
265	if (ret != 0) {
266		pr_err("cannot register miscdev on minor=%d (err=%d)\n",
267		       WATCHDOG_MINOR, ret);
268		goto unreg_regions;
269	}
270	pr_info("initialized. timeout=%d sec (nowayout=%d)\n",
271		timeout, nowayout);
272out:
273	return ret;
274unreg_regions:
275	release_region(wdt_start, 1);
276unreg_stop:
277	if (wdt_stop != wdt_start)
278		release_region(wdt_stop, 1);
279	goto out;
280}
281
282static void advwdt_remove(struct platform_device *dev)
283{
284	misc_deregister(&advwdt_miscdev);
285	release_region(wdt_start, 1);
286	if (wdt_stop != wdt_start)
287		release_region(wdt_stop, 1);
288}
289
290static void advwdt_shutdown(struct platform_device *dev)
291{
292	/* Turn the WDT off if we have a soft shutdown */
293	advwdt_disable();
294}
295
296static struct platform_driver advwdt_driver = {
297	.remove_new	= advwdt_remove,
298	.shutdown	= advwdt_shutdown,
299	.driver		= {
300		.name	= DRV_NAME,
301	},
302};
303
304static int __init advwdt_init(void)
305{
306	int err;
307
308	pr_info("WDT driver for Advantech single board computer initialising\n");
309
310	advwdt_platform_device = platform_device_register_simple(DRV_NAME,
311								-1, NULL, 0);
312	if (IS_ERR(advwdt_platform_device))
313		return PTR_ERR(advwdt_platform_device);
314
315	err = platform_driver_probe(&advwdt_driver, advwdt_probe);
316	if (err)
317		goto unreg_platform_device;
318
319	return 0;
320
321unreg_platform_device:
322	platform_device_unregister(advwdt_platform_device);
323	return err;
324}
325
326static void __exit advwdt_exit(void)
327{
328	platform_device_unregister(advwdt_platform_device);
329	platform_driver_unregister(&advwdt_driver);
330	pr_info("Watchdog Module Unloaded\n");
331}
332
333module_init(advwdt_init);
334module_exit(advwdt_exit);
335
336MODULE_LICENSE("GPL");
337MODULE_AUTHOR("Marek Michalkiewicz <marekm@linux.org.pl>");
338MODULE_DESCRIPTION("Advantech Single Board Computer WDT driver");
339