ib700wdt.c

  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	.write		= ibwdt_write,
260	.unlocked_ioctl	= ibwdt_ioctl,
261	.compat_ioctl	= compat_ptr_ioctl,
262	.open		= ibwdt_open,
263	.release	= ibwdt_close,
264};
265
266static struct miscdevice ibwdt_miscdev = {
267	.minor = WATCHDOG_MINOR,
268	.name = "watchdog",
269	.fops = &ibwdt_fops,
270};
271
272/*
273 *	Init & exit routines
274 */
275
276static int __init ibwdt_probe(struct platform_device *dev)
277{
278	int res;
279
280#if WDT_START != WDT_STOP
281	if (!request_region(WDT_STOP, 1, "IB700 WDT")) {
282		pr_err("STOP method I/O %X is not available\n", WDT_STOP);
283		res = -EIO;
284		goto out_nostopreg;
285	}
286#endif
287
288	if (!request_region(WDT_START, 1, "IB700 WDT")) {
289		pr_err("START method I/O %X is not available\n", WDT_START);
290		res = -EIO;
291		goto out_nostartreg;
292	}
293
294	/* Check that the heartbeat value is within it's range ;
295	 * if not reset to the default */
296	if (ibwdt_set_heartbeat(timeout)) {
297		ibwdt_set_heartbeat(WATCHDOG_TIMEOUT);
298		pr_info("timeout value must be 0<=x<=30, using %d\n", timeout);
299	}
300
301	res = misc_register(&ibwdt_miscdev);
302	if (res) {
303		pr_err("failed to register misc device\n");
304		goto out_nomisc;
305	}
306	return 0;
307
308out_nomisc:
309	release_region(WDT_START, 1);
310out_nostartreg:
311#if WDT_START != WDT_STOP
312	release_region(WDT_STOP, 1);
313#endif
314out_nostopreg:
315	return res;
316}
317
318static void ibwdt_remove(struct platform_device *dev)
319{
320	misc_deregister(&ibwdt_miscdev);
321	release_region(WDT_START, 1);
322#if WDT_START != WDT_STOP
323	release_region(WDT_STOP, 1);
324#endif
325}
326
327static void ibwdt_shutdown(struct platform_device *dev)
328{
329	/* Turn the WDT off if we have a soft shutdown */
330	ibwdt_disable();
331}
332
333static struct platform_driver ibwdt_driver = {
334	.remove		= ibwdt_remove,
335	.shutdown	= ibwdt_shutdown,
336	.driver		= {
337		.name	= DRV_NAME,
338	},
339};
340
341static int __init ibwdt_init(void)
342{
343	int err;
344
345	pr_info("WDT driver for IB700 single board computer initialising\n");
346
347	ibwdt_platform_device = platform_device_register_simple(DRV_NAME,
348								-1, NULL, 0);
349	if (IS_ERR(ibwdt_platform_device))
350		return PTR_ERR(ibwdt_platform_device);
351
352	err = platform_driver_probe(&ibwdt_driver, ibwdt_probe);
353	if (err)
354		goto unreg_platform_device;
355
356	return 0;
357
358unreg_platform_device:
359	platform_device_unregister(ibwdt_platform_device);
360	return err;
361}
362
363static void __exit ibwdt_exit(void)
364{
365	platform_device_unregister(ibwdt_platform_device);
366	platform_driver_unregister(&ibwdt_driver);
367	pr_info("Watchdog Module Unloaded\n");
368}
369
370module_init(ibwdt_init);
371module_exit(ibwdt_exit);
372
373MODULE_AUTHOR("Charles Howes <chowes@vsol.net>");
374MODULE_DESCRIPTION("IB700 SBC watchdog driver");
375MODULE_LICENSE("GPL");
376
377/* end of ib700wdt.c */