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, addr: &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, addr: &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(value: (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 addr: &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 addr: &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, addr: &wdt_status))
126 return -EBUSY;
127
128 wdt_enable();
129
130 return stream_open(inode, filp: 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, addr: &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, addr: &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(to: (void __user *)arg, from: &ident, n: 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(t: 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 .write = fop_write,
209 .open = fop_open,
210 .release = fop_close,
211 .unlocked_ioctl = fop_ioctl,
212 .compat_ioctl = compat_ptr_ioctl,
213};
214
215static struct miscdevice wdt_miscdev = {
216 .minor = WATCHDOG_MINOR,
217 .name = "watchdog",
218 .fops = &wdt_fops,
219};
220
221/*
222 * Notifier for system down
223 */
224
225static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
226 void *unused)
227{
228 if (code == SYS_DOWN || code == SYS_HALT)
229 wdt_disable();
230 return NOTIFY_DONE;
231}
232
233static struct notifier_block wdt_notifier = {
234 .notifier_call = wdt_notify_sys,
235};
236
237static void __exit sbc7240_wdt_unload(void)
238{
239 pr_info("Removing watchdog\n");
240 misc_deregister(misc: &wdt_miscdev);
241
242 unregister_reboot_notifier(&wdt_notifier);
243 release_region(SBC7240_ENABLE_PORT, 1);
244}
245
246static int __init sbc7240_wdt_init(void)
247{
248 int rc = -EBUSY;
249
250 if (!request_region(SBC7240_ENABLE_PORT, 1, "SBC7240 WDT")) {
251 pr_err("I/O address 0x%04x already in use\n",
252 SBC7240_ENABLE_PORT);
253 rc = -EIO;
254 goto err_out;
255 }
256
257 /* The IO port 0x043 used to disable the watchdog
258 * is already claimed by the system timer, so we
259 * can't request_region() it ...*/
260
261 if (timeout < 1 || timeout > SBC7240_MAX_TIMEOUT) {
262 timeout = SBC7240_TIMEOUT;
263 pr_info("timeout value must be 1<=x<=%d, using %d\n",
264 SBC7240_MAX_TIMEOUT, timeout);
265 }
266 wdt_set_timeout(t: timeout);
267 wdt_disable();
268
269 rc = register_reboot_notifier(&wdt_notifier);
270 if (rc) {
271 pr_err("cannot register reboot notifier (err=%d)\n", rc);
272 goto err_out_region;
273 }
274
275 rc = misc_register(misc: &wdt_miscdev);
276 if (rc) {
277 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
278 wdt_miscdev.minor, rc);
279 goto err_out_reboot_notifier;
280 }
281
282 pr_info("Watchdog driver for SBC7240 initialised (nowayout=%d)\n",
283 nowayout);
284
285 return 0;
286
287err_out_reboot_notifier:
288 unregister_reboot_notifier(&wdt_notifier);
289err_out_region:
290 release_region(SBC7240_ENABLE_PORT, 1);
291err_out:
292 return rc;
293}
294
295module_init(sbc7240_wdt_init);
296module_exit(sbc7240_wdt_unload);
297
298MODULE_AUTHOR("Gilles Gigan");
299MODULE_DESCRIPTION("Watchdog device driver for single board"
300 " computers EPIC Nano 7240 from iEi");
301MODULE_LICENSE("GPL");
302

source code of linux/drivers/watchdog/sbc7240_wdt.c