1// SPDX-License-Identifier: GPL-2.0
2/*
3 *	NANO7240 SBC Watchdog device driver
4 *
5 *	Based on w83877f.c by Scott Jennings,
6 *
7 *	(c) Copyright 2007  Gilles GIGAN <gilles.gigan@jcu.edu.au>
8 */
9
10#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11
12#include <linux/fs.h>
13#include <linux/init.h>
14#include <linux/ioport.h>
15#include <linux/jiffies.h>
16#include <linux/module.h>
17#include <linux/moduleparam.h>
18#include <linux/miscdevice.h>
19#include <linux/notifier.h>
20#include <linux/reboot.h>
21#include <linux/types.h>
22#include <linux/watchdog.h>
23#include <linux/io.h>
24#include <linux/uaccess.h>
25#include <linux/atomic.h>
26
27#define SBC7240_ENABLE_PORT		0x443
28#define SBC7240_DISABLE_PORT		0x043
29#define SBC7240_SET_TIMEOUT_PORT	SBC7240_ENABLE_PORT
30#define SBC7240_MAGIC_CHAR		'V'
31
32#define SBC7240_TIMEOUT		30
33#define SBC7240_MAX_TIMEOUT		255
34static int timeout = SBC7240_TIMEOUT;	/* in seconds */
35module_param(timeout, int, 0);
36MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. (1<=timeout<="
37		 __MODULE_STRING(SBC7240_MAX_TIMEOUT) ", default="
38		 __MODULE_STRING(SBC7240_TIMEOUT) ")");
39
40static bool nowayout = WATCHDOG_NOWAYOUT;
41module_param(nowayout, bool, 0);
42MODULE_PARM_DESC(nowayout, "Disable watchdog when closing device file");
43
44#define SBC7240_OPEN_STATUS_BIT		0
45#define SBC7240_ENABLED_STATUS_BIT	1
46#define SBC7240_EXPECT_CLOSE_STATUS_BIT	2
47static unsigned long wdt_status;
48
49/*
50 * Utility routines
51 */
52
53static void wdt_disable(void)
54{
55	/* disable the watchdog */
56	if (test_and_clear_bit(SBC7240_ENABLED_STATUS_BIT, &wdt_status)) {
57		inb_p(SBC7240_DISABLE_PORT);
58		pr_info("Watchdog timer is now disabled\n");
59	}
60}
61
62static void wdt_enable(void)
63{
64	/* enable the watchdog */
65	if (!test_and_set_bit(SBC7240_ENABLED_STATUS_BIT, &wdt_status)) {
66		inb_p(SBC7240_ENABLE_PORT);
67		pr_info("Watchdog timer is now enabled\n");
68	}
69}
70
71static int wdt_set_timeout(int t)
72{
73	if (t < 1 || t > SBC7240_MAX_TIMEOUT) {
74		pr_err("timeout value must be 1<=x<=%d\n", SBC7240_MAX_TIMEOUT);
75		return -1;
76	}
77	/* set the timeout */
78	outb_p((unsigned)t, SBC7240_SET_TIMEOUT_PORT);
79	timeout = t;
80	pr_info("timeout set to %d seconds\n", t);
81	return 0;
82}
83
84/* Whack the dog */
85static inline void wdt_keepalive(void)
86{
87	if (test_bit(SBC7240_ENABLED_STATUS_BIT, &wdt_status))
88		inb_p(SBC7240_ENABLE_PORT);
89}
90
91/*
92 * /dev/watchdog handling
93 */
94static ssize_t fop_write(struct file *file, const char __user *buf,
95			 size_t count, loff_t *ppos)
96{
97	size_t i;
98	char c;
99
100	if (count) {
101		if (!nowayout) {
102			clear_bit(SBC7240_EXPECT_CLOSE_STATUS_BIT,
103				&wdt_status);
104
105			/* is there a magic char ? */
106			for (i = 0; i != count; i++) {
107				if (get_user(c, buf + i))
108					return -EFAULT;
109				if (c == SBC7240_MAGIC_CHAR) {
110					set_bit(SBC7240_EXPECT_CLOSE_STATUS_BIT,
111						&wdt_status);
112					break;
113				}
114			}
115		}
116
117		wdt_keepalive();
118	}
119
120	return count;
121}
122
123static int fop_open(struct inode *inode, struct file *file)
124{
125	if (test_and_set_bit(SBC7240_OPEN_STATUS_BIT, &wdt_status))
126		return -EBUSY;
127
128	wdt_enable();
129
130	return stream_open(inode, file);
131}
132
133static int fop_close(struct inode *inode, struct file *file)
134{
135	if (test_and_clear_bit(SBC7240_EXPECT_CLOSE_STATUS_BIT, &wdt_status)
136	    || !nowayout) {
137		wdt_disable();
138	} else {
139		pr_crit("Unexpected close, not stopping watchdog!\n");
140		wdt_keepalive();
141	}
142
143	clear_bit(SBC7240_OPEN_STATUS_BIT, &wdt_status);
144	return 0;
145}
146
147static const struct watchdog_info ident = {
148	.options = WDIOF_KEEPALIVEPING|
149		   WDIOF_SETTIMEOUT|
150		   WDIOF_MAGICCLOSE,
151	.firmware_version = 1,
152	.identity = "SBC7240",
153};
154
155
156static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
157{
158	switch (cmd) {
159	case WDIOC_GETSUPPORT:
160		return copy_to_user((void __user *)arg, &ident, sizeof(ident))
161						 ? -EFAULT : 0;
162	case WDIOC_GETSTATUS:
163	case WDIOC_GETBOOTSTATUS:
164		return put_user(0, (int __user *)arg);
165	case WDIOC_SETOPTIONS:
166	{
167		int options;
168		int retval = -EINVAL;
169
170		if (get_user(options, (int __user *)arg))
171			return -EFAULT;
172
173		if (options & WDIOS_DISABLECARD) {
174			wdt_disable();
175			retval = 0;
176		}
177
178		if (options & WDIOS_ENABLECARD) {
179			wdt_enable();
180			retval = 0;
181		}
182
183		return retval;
184	}
185	case WDIOC_KEEPALIVE:
186		wdt_keepalive();
187		return 0;
188	case WDIOC_SETTIMEOUT:
189	{
190		int new_timeout;
191
192		if (get_user(new_timeout, (int __user *)arg))
193			return -EFAULT;
194
195		if (wdt_set_timeout(new_timeout))
196			return -EINVAL;
197	}
198		fallthrough;
199	case WDIOC_GETTIMEOUT:
200		return put_user(timeout, (int __user *)arg);
201	default:
202		return -ENOTTY;
203	}
204}
205
206static const struct file_operations wdt_fops = {
207	.owner = THIS_MODULE,
208	.llseek = no_llseek,
209	.write = fop_write,
210	.open = fop_open,
211	.release = fop_close,
212	.unlocked_ioctl = fop_ioctl,
213	.compat_ioctl = compat_ptr_ioctl,
214};
215
216static struct miscdevice wdt_miscdev = {
217	.minor = WATCHDOG_MINOR,
218	.name = "watchdog",
219	.fops = &wdt_fops,
220};
221
222/*
223 *	Notifier for system down
224 */
225
226static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
227			  void *unused)
228{
229	if (code == SYS_DOWN || code == SYS_HALT)
230		wdt_disable();
231	return NOTIFY_DONE;
232}
233
234static struct notifier_block wdt_notifier = {
235	.notifier_call = wdt_notify_sys,
236};
237
238static void __exit sbc7240_wdt_unload(void)
239{
240	pr_info("Removing watchdog\n");
241	misc_deregister(&wdt_miscdev);
242
243	unregister_reboot_notifier(&wdt_notifier);
244	release_region(SBC7240_ENABLE_PORT, 1);
245}
246
247static int __init sbc7240_wdt_init(void)
248{
249	int rc = -EBUSY;
250
251	if (!request_region(SBC7240_ENABLE_PORT, 1, "SBC7240 WDT")) {
252		pr_err("I/O address 0x%04x already in use\n",
253		       SBC7240_ENABLE_PORT);
254		rc = -EIO;
255		goto err_out;
256	}
257
258	/* The IO port 0x043 used to disable the watchdog
259	 * is already claimed by the system timer, so we
260	 * can't request_region() it ...*/
261
262	if (timeout < 1 || timeout > SBC7240_MAX_TIMEOUT) {
263		timeout = SBC7240_TIMEOUT;
264		pr_info("timeout value must be 1<=x<=%d, using %d\n",
265			SBC7240_MAX_TIMEOUT, timeout);
266	}
267	wdt_set_timeout(timeout);
268	wdt_disable();
269
270	rc = register_reboot_notifier(&wdt_notifier);
271	if (rc) {
272		pr_err("cannot register reboot notifier (err=%d)\n", rc);
273		goto err_out_region;
274	}
275
276	rc = misc_register(&wdt_miscdev);
277	if (rc) {
278		pr_err("cannot register miscdev on minor=%d (err=%d)\n",
279		       wdt_miscdev.minor, rc);
280		goto err_out_reboot_notifier;
281	}
282
283	pr_info("Watchdog driver for SBC7240 initialised (nowayout=%d)\n",
284		nowayout);
285
286	return 0;
287
288err_out_reboot_notifier:
289	unregister_reboot_notifier(&wdt_notifier);
290err_out_region:
291	release_region(SBC7240_ENABLE_PORT, 1);
292err_out:
293	return rc;
294}
295
296module_init(sbc7240_wdt_init);
297module_exit(sbc7240_wdt_unload);
298
299MODULE_AUTHOR("Gilles Gigan");
300MODULE_DESCRIPTION("Watchdog device driver for single board"
301		   " computers EPIC Nano 7240 from iEi");
302MODULE_LICENSE("GPL");
303