1// SPDX-License-Identifier: GPL-2.0+
2/*
3 *	IB700 Single Board Computer WDT driver
4 *
5 *	(c) Copyright 2001 Charles Howes <chowes@vsol.net>
6 *
7 *	Based on advantechwdt.c which is based on acquirewdt.c which
8 *	is based on wdt.c.
9 *
10 *	(c) Copyright 2000-2001 Marek Michalkiewicz <marekm@linux.org.pl>
11 *
12 *	Based on acquirewdt.c which is based on wdt.c.
13 *	Original copyright messages:
14 *
15 *	(c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
16 *						All Rights Reserved.
17 *
18 *	Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
19 *	warranty for any of this software. This material is provided
20 *	"AS-IS" and at no charge.
21 *
22 *	(c) Copyright 1995    Alan Cox <alan@lxorguk.ukuu.org.uk>
23 *
24 *	14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
25 *	     Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
26 *	     Added timeout module option to override default
27 *
28 */
29
30#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
31
32#include <linux/module.h>
33#include <linux/types.h>
34#include <linux/miscdevice.h>
35#include <linux/watchdog.h>
36#include <linux/ioport.h>
37#include <linux/fs.h>
38#include <linux/init.h>
39#include <linux/spinlock.h>
40#include <linux/moduleparam.h>
41#include <linux/platform_device.h>
42#include <linux/io.h>
43#include <linux/uaccess.h>
44
45
46static struct platform_device *ibwdt_platform_device;
47static unsigned long ibwdt_is_open;
48static DEFINE_SPINLOCK(ibwdt_lock);
49static char expect_close;
50
51/* Module information */
52#define DRV_NAME "ib700wdt"
53
54/*
55 *
56 * Watchdog Timer Configuration
57 *
58 * The function of the watchdog timer is to reset the system
59 * automatically and is defined at I/O port 0443H.  To enable the
60 * watchdog timer and allow the system to reset, write I/O port 0443H.
61 * To disable the timer, write I/O port 0441H for the system to stop the
62 * watchdog function.  The timer has a tolerance of 20% for its
63 * intervals.
64 *
65 * The following describes how the timer should be programmed.
66 *
67 * Enabling Watchdog:
68 * MOV AX,000FH (Choose the values from 0 to F)
69 * MOV DX,0443H
70 * OUT DX,AX
71 *
72 * Disabling Watchdog:
73 * MOV AX,000FH (Any value is fine.)
74 * MOV DX,0441H
75 * OUT DX,AX
76 *
77 * Watchdog timer control table:
78 * Level   Value  Time/sec | Level Value Time/sec
79 *   1       F       0     |   9     7      16
80 *   2       E       2     |   10    6      18
81 *   3       D       4     |   11    5      20
82 *   4       C       6     |   12    4      22
83 *   5       B       8     |   13    3      24
84 *   6       A       10    |   14    2      26
85 *   7       9       12    |   15    1      28
86 *   8       8       14    |   16    0      30
87 *
88 */
89
90#define WDT_STOP 0x441
91#define WDT_START 0x443
92
93/* Default timeout */
94#define WATCHDOG_TIMEOUT 30		/* 30 seconds +/- 20% */
95static int timeout = WATCHDOG_TIMEOUT;	/* in seconds */
96module_param(timeout, int, 0);
97MODULE_PARM_DESC(timeout,
98	"Watchdog timeout in seconds. 0<= timeout <=30, default="
99		__MODULE_STRING(WATCHDOG_TIMEOUT) ".");
100
101static bool nowayout = WATCHDOG_NOWAYOUT;
102module_param(nowayout, bool, 0);
103MODULE_PARM_DESC(nowayout,
104		"Watchdog cannot be stopped once started (default="
105				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
106
107
108/*
109 *	Watchdog Operations
110 */
111
112static void ibwdt_ping(void)
113{
114	int wd_margin = 15 - ((timeout + 1) / 2);
115
116	spin_lock(&ibwdt_lock);
117
118	/* Write a watchdog value */
119	outb_p(wd_margin, WDT_START);
120
121	spin_unlock(&ibwdt_lock);
122}
123
124static void ibwdt_disable(void)
125{
126	spin_lock(&ibwdt_lock);
127	outb_p(0, WDT_STOP);
128	spin_unlock(&ibwdt_lock);
129}
130
131static int ibwdt_set_heartbeat(int t)
132{
133	if (t < 0 || t > 30)
134		return -EINVAL;
135
136	timeout = t;
137	return 0;
138}
139
140/*
141 *	/dev/watchdog handling
142 */
143
144static ssize_t ibwdt_write(struct file *file, const char __user *buf,
145						size_t count, loff_t *ppos)
146{
147	if (count) {
148		if (!nowayout) {
149			size_t i;
150
151			/* In case it was set long ago */
152			expect_close = 0;
153
154			for (i = 0; i != count; i++) {
155				char c;
156				if (get_user(c, buf + i))
157					return -EFAULT;
158				if (c == 'V')
159					expect_close = 42;
160			}
161		}
162		ibwdt_ping();
163	}
164	return count;
165}
166
167static long ibwdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
168{
169	int new_margin;
170	void __user *argp = (void __user *)arg;
171	int __user *p = argp;
172
173	static const struct watchdog_info ident = {
174		.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT
175							| WDIOF_MAGICCLOSE,
176		.firmware_version = 1,
177		.identity = "IB700 WDT",
178	};
179
180	switch (cmd) {
181	case WDIOC_GETSUPPORT:
182		if (copy_to_user(argp, &ident, sizeof(ident)))
183			return -EFAULT;
184		break;
185
186	case WDIOC_GETSTATUS:
187	case WDIOC_GETBOOTSTATUS:
188		return put_user(0, p);
189
190	case WDIOC_SETOPTIONS:
191	{
192		int options, retval = -EINVAL;
193
194		if (get_user(options, p))
195			return -EFAULT;
196
197		if (options & WDIOS_DISABLECARD) {
198			ibwdt_disable();
199			retval = 0;
200		}
201		if (options & WDIOS_ENABLECARD) {
202			ibwdt_ping();
203			retval = 0;
204		}
205		return retval;
206	}
207	case WDIOC_KEEPALIVE:
208		ibwdt_ping();
209		break;
210
211	case WDIOC_SETTIMEOUT:
212		if (get_user(new_margin, p))
213			return -EFAULT;
214		if (ibwdt_set_heartbeat(new_margin))
215			return -EINVAL;
216		ibwdt_ping();
217		fallthrough;
218
219	case WDIOC_GETTIMEOUT:
220		return put_user(timeout, p);
221
222	default:
223		return -ENOTTY;
224	}
225	return 0;
226}
227
228static int ibwdt_open(struct inode *inode, struct file *file)
229{
230	if (test_and_set_bit(0, &ibwdt_is_open))
231		return -EBUSY;
232	if (nowayout)
233		__module_get(THIS_MODULE);
234
235	/* Activate */
236	ibwdt_ping();
237	return stream_open(inode, file);
238}
239
240static int ibwdt_close(struct inode *inode, struct file *file)
241{
242	if (expect_close == 42) {
243		ibwdt_disable();
244	} else {
245		pr_crit("WDT device closed unexpectedly.  WDT will not stop!\n");
246		ibwdt_ping();
247	}
248	clear_bit(0, &ibwdt_is_open);
249	expect_close = 0;
250	return 0;
251}
252
253/*
254 *	Kernel Interfaces
255 */
256
257static const struct file_operations ibwdt_fops = {
258	.owner		= THIS_MODULE,
259	.llseek		= no_llseek,
260	.write		= ibwdt_write,
261	.unlocked_ioctl	= ibwdt_ioctl,
262	.compat_ioctl	= compat_ptr_ioctl,
263	.open		= ibwdt_open,
264	.release	= ibwdt_close,
265};
266
267static struct miscdevice ibwdt_miscdev = {
268	.minor = WATCHDOG_MINOR,
269	.name = "watchdog",
270	.fops = &ibwdt_fops,
271};
272
273/*
274 *	Init & exit routines
275 */
276
277static int __init ibwdt_probe(struct platform_device *dev)
278{
279	int res;
280
281#if WDT_START != WDT_STOP
282	if (!request_region(WDT_STOP, 1, "IB700 WDT")) {
283		pr_err("STOP method I/O %X is not available\n", WDT_STOP);
284		res = -EIO;
285		goto out_nostopreg;
286	}
287#endif
288
289	if (!request_region(WDT_START, 1, "IB700 WDT")) {
290		pr_err("START method I/O %X is not available\n", WDT_START);
291		res = -EIO;
292		goto out_nostartreg;
293	}
294
295	/* Check that the heartbeat value is within it's range ;
296	 * if not reset to the default */
297	if (ibwdt_set_heartbeat(timeout)) {
298		ibwdt_set_heartbeat(WATCHDOG_TIMEOUT);
299		pr_info("timeout value must be 0<=x<=30, using %d\n", timeout);
300	}
301
302	res = misc_register(&ibwdt_miscdev);
303	if (res) {
304		pr_err("failed to register misc device\n");
305		goto out_nomisc;
306	}
307	return 0;
308
309out_nomisc:
310	release_region(WDT_START, 1);
311out_nostartreg:
312#if WDT_START != WDT_STOP
313	release_region(WDT_STOP, 1);
314#endif
315out_nostopreg:
316	return res;
317}
318
319static void ibwdt_remove(struct platform_device *dev)
320{
321	misc_deregister(&ibwdt_miscdev);
322	release_region(WDT_START, 1);
323#if WDT_START != WDT_STOP
324	release_region(WDT_STOP, 1);
325#endif
326}
327
328static void ibwdt_shutdown(struct platform_device *dev)
329{
330	/* Turn the WDT off if we have a soft shutdown */
331	ibwdt_disable();
332}
333
334static struct platform_driver ibwdt_driver = {
335	.remove_new	= ibwdt_remove,
336	.shutdown	= ibwdt_shutdown,
337	.driver		= {
338		.name	= DRV_NAME,
339	},
340};
341
342static int __init ibwdt_init(void)
343{
344	int err;
345
346	pr_info("WDT driver for IB700 single board computer initialising\n");
347
348	ibwdt_platform_device = platform_device_register_simple(DRV_NAME,
349								-1, NULL, 0);
350	if (IS_ERR(ibwdt_platform_device))
351		return PTR_ERR(ibwdt_platform_device);
352
353	err = platform_driver_probe(&ibwdt_driver, ibwdt_probe);
354	if (err)
355		goto unreg_platform_device;
356
357	return 0;
358
359unreg_platform_device:
360	platform_device_unregister(ibwdt_platform_device);
361	return err;
362}
363
364static void __exit ibwdt_exit(void)
365{
366	platform_device_unregister(ibwdt_platform_device);
367	platform_driver_unregister(&ibwdt_driver);
368	pr_info("Watchdog Module Unloaded\n");
369}
370
371module_init(ibwdt_init);
372module_exit(ibwdt_exit);
373
374MODULE_AUTHOR("Charles Howes <chowes@vsol.net>");
375MODULE_DESCRIPTION("IB700 SBC watchdog driver");
376MODULE_LICENSE("GPL");
377
378/* end of ib700wdt.c */
379