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1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * Acquire Single Board Computer Watchdog Timer driver
4 *
5 * Based on wdt.c. Original copyright messages:
6 *
7 * (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
8 * All Rights Reserved.
9 *
10 * Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
11 * warranty for any of this software. This material is provided
12 * "AS-IS" and at no charge.
13 *
14 * (c) Copyright 1995 Alan Cox <alan@lxorguk.ukuu.org.uk>
15 *
16 * 14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
17 * Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
18 * Can't add timeout - driver doesn't allow changing value
19 */
20
21/*
22 * Theory of Operation:
23 * The Watch-Dog Timer is provided to ensure that standalone
24 * Systems can always recover from catastrophic conditions that
25 * caused the CPU to crash. This condition may have occurred by
26 * external EMI or a software bug. When the CPU stops working
27 * correctly, hardware on the board will either perform a hardware
28 * reset (cold boot) or a non-maskable interrupt (NMI) to bring the
29 * system back to a known state.
30 *
31 * The Watch-Dog Timer is controlled by two I/O Ports.
32 * 443 hex - Read - Enable or refresh the Watch-Dog Timer
33 * 043 hex - Read - Disable the Watch-Dog Timer
34 *
35 * To enable the Watch-Dog Timer, a read from I/O port 443h must
36 * be performed. This will enable and activate the countdown timer
37 * which will eventually time out and either reset the CPU or cause
38 * an NMI depending on the setting of a jumper. To ensure that this
39 * reset condition does not occur, the Watch-Dog Timer must be
40 * periodically refreshed by reading the same I/O port 443h.
41 * The Watch-Dog Timer is disabled by reading I/O port 043h.
42 *
43 * The Watch-Dog Timer Time-Out Period is set via jumpers.
44 * It can be 1, 2, 10, 20, 110 or 220 seconds.
45 */
46
47/*
48 * Includes, defines, variables, module parameters, ...
49 */
50
51#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
52
53/* Includes */
54#include <linux/module.h> /* For module specific items */
55#include <linux/moduleparam.h> /* For new moduleparam's */
56#include <linux/types.h> /* For standard types (like size_t) */
57#include <linux/errno.h> /* For the -ENODEV/... values */
58#include <linux/kernel.h> /* For printk/panic/... */
59#include <linux/miscdevice.h> /* For struct miscdevice */
60#include <linux/watchdog.h> /* For the watchdog specific items */
61#include <linux/fs.h> /* For file operations */
62#include <linux/ioport.h> /* For io-port access */
63#include <linux/platform_device.h> /* For platform_driver framework */
64#include <linux/init.h> /* For __init/__exit/... */
65#include <linux/uaccess.h> /* For copy_to_user/put_user/... */
66#include <linux/io.h> /* For inb/outb/... */
67
68/* Module information */
69#define DRV_NAME "acquirewdt"
70#define WATCHDOG_NAME "Acquire WDT"
71/* There is no way to see what the correct time-out period is */
72#define WATCHDOG_HEARTBEAT 0
73
74/* internal variables */
75/* the watchdog platform device */
76static struct platform_device *acq_platform_device;
77static unsigned long acq_is_open;
78static char expect_close;
79
80/* module parameters */
81/* You must set this - there is no sane way to probe for this board. */
82static int wdt_stop = 0x43;
83module_param(wdt_stop, int, 0);
84MODULE_PARM_DESC(wdt_stop, "Acquire WDT 'stop' io port (default 0x43)");
85
86/* You must set this - there is no sane way to probe for this board. */
87static int wdt_start = 0x443;
88module_param(wdt_start, int, 0);
89MODULE_PARM_DESC(wdt_start, "Acquire WDT 'start' io port (default 0x443)");
90
91static bool nowayout = WATCHDOG_NOWAYOUT;
92module_param(nowayout, bool, 0);
93MODULE_PARM_DESC(nowayout,
94 "Watchdog cannot be stopped once started (default="
95 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
96
97/*
98 * Watchdog Operations
99 */
100
101static void acq_keepalive(void)
102{
103 /* Write a watchdog value */
104 inb_p(wdt_start);
105}
106
107static void acq_stop(void)
108{
109 /* Turn the card off */
110 inb_p(wdt_stop);
111}
112
113/*
114 * /dev/watchdog handling
115 */
116
117static ssize_t acq_write(struct file *file, const char __user *buf,
118 size_t count, loff_t *ppos)
119{
120 /* See if we got the magic character 'V' and reload the timer */
121 if (count) {
122 if (!nowayout) {
123 size_t i;
124 /* note: just in case someone wrote the magic character
125 five months ago... */
126 expect_close = 0;
127 /* scan to see whether or not we got the
128 magic character */
129 for (i = 0; i != count; i++) {
130 char c;
131 if (get_user(c, buf + i))
132 return -EFAULT;
133 if (c == 'V')
134 expect_close = 42;
135 }
136 }
137 /* Well, anyhow someone wrote to us, we should
138 return that favour */
139 acq_keepalive();
140 }
141 return count;
142}
143
144static long acq_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
145{
146 int options, retval = -EINVAL;
147 void __user *argp = (void __user *)arg;
148 int __user *p = argp;
149 static const struct watchdog_info ident = {
150 .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
151 .firmware_version = 1,
152 .identity = WATCHDOG_NAME,
153 };
154
155 switch (cmd) {
156 case WDIOC_GETSUPPORT:
157 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
158
159 case WDIOC_GETSTATUS:
160 case WDIOC_GETBOOTSTATUS:
161 return put_user(0, p);
162
163 case WDIOC_SETOPTIONS:
164 {
165 if (get_user(options, p))
166 return -EFAULT;
167 if (options & WDIOS_DISABLECARD) {
168 acq_stop();
169 retval = 0;
170 }
171 if (options & WDIOS_ENABLECARD) {
172 acq_keepalive();
173 retval = 0;
174 }
175 return retval;
176 }
177 case WDIOC_KEEPALIVE:
178 acq_keepalive();
179 return 0;
180
181 case WDIOC_GETTIMEOUT:
182 return put_user(WATCHDOG_HEARTBEAT, p);
183
184 default:
185 return -ENOTTY;
186 }
187}
188
189static int acq_open(struct inode *inode, struct file *file)
190{
191 if (test_and_set_bit(0, &acq_is_open))
192 return -EBUSY;
193
194 if (nowayout)
195 __module_get(THIS_MODULE);
196
197 /* Activate */
198 acq_keepalive();
199 return stream_open(inode, file);
200}
201
202static int acq_close(struct inode *inode, struct file *file)
203{
204 if (expect_close == 42) {
205 acq_stop();
206 } else {
207 pr_crit("Unexpected close, not stopping watchdog!\n");
208 acq_keepalive();
209 }
210 clear_bit(0, &acq_is_open);
211 expect_close = 0;
212 return 0;
213}
214
215/*
216 * Kernel Interfaces
217 */
218
219static const struct file_operations acq_fops = {
220 .owner = THIS_MODULE,
221 .llseek = no_llseek,
222 .write = acq_write,
223 .unlocked_ioctl = acq_ioctl,
224 .compat_ioctl = compat_ptr_ioctl,
225 .open = acq_open,
226 .release = acq_close,
227};
228
229static struct miscdevice acq_miscdev = {
230 .minor = WATCHDOG_MINOR,
231 .name = "watchdog",
232 .fops = &acq_fops,
233};
234
235/*
236 * Init & exit routines
237 */
238
239static int __init acq_probe(struct platform_device *dev)
240{
241 int ret;
242
243 if (wdt_stop != wdt_start) {
244 if (!request_region(wdt_stop, 1, WATCHDOG_NAME)) {
245 pr_err("I/O address 0x%04x already in use\n", 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 ret = misc_register(&acq_miscdev);
257 if (ret != 0) {
258 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
259 WATCHDOG_MINOR, ret);
260 goto unreg_regions;
261 }
262 pr_info("initialized. (nowayout=%d)\n", nowayout);
263
264 return 0;
265unreg_regions:
266 release_region(wdt_start, 1);
267unreg_stop:
268 if (wdt_stop != wdt_start)
269 release_region(wdt_stop, 1);
270out:
271 return ret;
272}
273
274static void acq_remove(struct platform_device *dev)
275{
276 misc_deregister(&acq_miscdev);
277 release_region(wdt_start, 1);
278 if (wdt_stop != wdt_start)
279 release_region(wdt_stop, 1);
280}
281
282static void acq_shutdown(struct platform_device *dev)
283{
284 /* Turn the WDT off if we have a soft shutdown */
285 acq_stop();
286}
287
288static struct platform_driver acquirewdt_driver = {
289 .remove_new = acq_remove,
290 .shutdown = acq_shutdown,
291 .driver = {
292 .name = DRV_NAME,
293 },
294};
295
296static int __init acq_init(void)
297{
298 int err;
299
300 pr_info("WDT driver for Acquire single board computer initialising\n");
301
302 acq_platform_device = platform_device_register_simple(DRV_NAME,
303 -1, NULL, 0);
304 if (IS_ERR(acq_platform_device))
305 return PTR_ERR(acq_platform_device);
306
307 err = platform_driver_probe(&acquirewdt_driver, acq_probe);
308 if (err)
309 goto unreg_platform_device;
310 return 0;
311
312unreg_platform_device:
313 platform_device_unregister(acq_platform_device);
314 return err;
315}
316
317static void __exit acq_exit(void)
318{
319 platform_device_unregister(acq_platform_device);
320 platform_driver_unregister(&acquirewdt_driver);
321 pr_info("Watchdog Module Unloaded\n");
322}
323
324module_init(acq_init);
325module_exit(acq_exit);
326
327MODULE_AUTHOR("David Woodhouse");
328MODULE_DESCRIPTION("Acquire Inc. Single Board Computer Watchdog Timer driver");
329MODULE_LICENSE("GPL");
1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * Acquire Single Board Computer Watchdog Timer driver
4 *
5 * Based on wdt.c. Original copyright messages:
6 *
7 * (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
8 * All Rights Reserved.
9 *
10 * Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
11 * warranty for any of this software. This material is provided
12 * "AS-IS" and at no charge.
13 *
14 * (c) Copyright 1995 Alan Cox <alan@lxorguk.ukuu.org.uk>
15 *
16 * 14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
17 * Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
18 * Can't add timeout - driver doesn't allow changing value
19 */
20
21/*
22 * Theory of Operation:
23 * The Watch-Dog Timer is provided to ensure that standalone
24 * Systems can always recover from catastrophic conditions that
25 * caused the CPU to crash. This condition may have occurred by
26 * external EMI or a software bug. When the CPU stops working
27 * correctly, hardware on the board will either perform a hardware
28 * reset (cold boot) or a non-maskable interrupt (NMI) to bring the
29 * system back to a known state.
30 *
31 * The Watch-Dog Timer is controlled by two I/O Ports.
32 * 443 hex - Read - Enable or refresh the Watch-Dog Timer
33 * 043 hex - Read - Disable the Watch-Dog Timer
34 *
35 * To enable the Watch-Dog Timer, a read from I/O port 443h must
36 * be performed. This will enable and activate the countdown timer
37 * which will eventually time out and either reset the CPU or cause
38 * an NMI depending on the setting of a jumper. To ensure that this
39 * reset condition does not occur, the Watch-Dog Timer must be
40 * periodically refreshed by reading the same I/O port 443h.
41 * The Watch-Dog Timer is disabled by reading I/O port 043h.
42 *
43 * The Watch-Dog Timer Time-Out Period is set via jumpers.
44 * It can be 1, 2, 10, 20, 110 or 220 seconds.
45 */
46
47/*
48 * Includes, defines, variables, module parameters, ...
49 */
50
51#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
52
53/* Includes */
54#include <linux/module.h> /* For module specific items */
55#include <linux/moduleparam.h> /* For new moduleparam's */
56#include <linux/types.h> /* For standard types (like size_t) */
57#include <linux/errno.h> /* For the -ENODEV/... values */
58#include <linux/kernel.h> /* For printk/panic/... */
59#include <linux/miscdevice.h> /* For struct miscdevice */
60#include <linux/watchdog.h> /* For the watchdog specific items */
61#include <linux/fs.h> /* For file operations */
62#include <linux/ioport.h> /* For io-port access */
63#include <linux/platform_device.h> /* For platform_driver framework */
64#include <linux/init.h> /* For __init/__exit/... */
65#include <linux/uaccess.h> /* For copy_to_user/put_user/... */
66#include <linux/io.h> /* For inb/outb/... */
67
68/* Module information */
69#define DRV_NAME "acquirewdt"
70#define WATCHDOG_NAME "Acquire WDT"
71/* There is no way to see what the correct time-out period is */
72#define WATCHDOG_HEARTBEAT 0
73
74/* internal variables */
75/* the watchdog platform device */
76static struct platform_device *acq_platform_device;
77static unsigned long acq_is_open;
78static char expect_close;
79
80/* module parameters */
81/* You must set this - there is no sane way to probe for this board. */
82static int wdt_stop = 0x43;
83module_param(wdt_stop, int, 0);
84MODULE_PARM_DESC(wdt_stop, "Acquire WDT 'stop' io port (default 0x43)");
85
86/* You must set this - there is no sane way to probe for this board. */
87static int wdt_start = 0x443;
88module_param(wdt_start, int, 0);
89MODULE_PARM_DESC(wdt_start, "Acquire WDT 'start' io port (default 0x443)");
90
91static bool nowayout = WATCHDOG_NOWAYOUT;
92module_param(nowayout, bool, 0);
93MODULE_PARM_DESC(nowayout,
94 "Watchdog cannot be stopped once started (default="
95 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
96
97/*
98 * Watchdog Operations
99 */
100
101static void acq_keepalive(void)
102{
103 /* Write a watchdog value */
104 inb_p(wdt_start);
105}
106
107static void acq_stop(void)
108{
109 /* Turn the card off */
110 inb_p(wdt_stop);
111}
112
113/*
114 * /dev/watchdog handling
115 */
116
117static ssize_t acq_write(struct file *file, const char __user *buf,
118 size_t count, loff_t *ppos)
119{
120 /* See if we got the magic character 'V' and reload the timer */
121 if (count) {
122 if (!nowayout) {
123 size_t i;
124 /* note: just in case someone wrote the magic character
125 five months ago... */
126 expect_close = 0;
127 /* scan to see whether or not we got the
128 magic character */
129 for (i = 0; i != count; i++) {
130 char c;
131 if (get_user(c, buf + i))
132 return -EFAULT;
133 if (c == 'V')
134 expect_close = 42;
135 }
136 }
137 /* Well, anyhow someone wrote to us, we should
138 return that favour */
139 acq_keepalive();
140 }
141 return count;
142}
143
144static long acq_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
145{
146 int options, retval = -EINVAL;
147 void __user *argp = (void __user *)arg;
148 int __user *p = argp;
149 static const struct watchdog_info ident = {
150 .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
151 .firmware_version = 1,
152 .identity = WATCHDOG_NAME,
153 };
154
155 switch (cmd) {
156 case WDIOC_GETSUPPORT:
157 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
158
159 case WDIOC_GETSTATUS:
160 case WDIOC_GETBOOTSTATUS:
161 return put_user(0, p);
162
163 case WDIOC_SETOPTIONS:
164 {
165 if (get_user(options, p))
166 return -EFAULT;
167 if (options & WDIOS_DISABLECARD) {
168 acq_stop();
169 retval = 0;
170 }
171 if (options & WDIOS_ENABLECARD) {
172 acq_keepalive();
173 retval = 0;
174 }
175 return retval;
176 }
177 case WDIOC_KEEPALIVE:
178 acq_keepalive();
179 return 0;
180
181 case WDIOC_GETTIMEOUT:
182 return put_user(WATCHDOG_HEARTBEAT, p);
183
184 default:
185 return -ENOTTY;
186 }
187}
188
189static int acq_open(struct inode *inode, struct file *file)
190{
191 if (test_and_set_bit(0, &acq_is_open))
192 return -EBUSY;
193
194 if (nowayout)
195 __module_get(THIS_MODULE);
196
197 /* Activate */
198 acq_keepalive();
199 return stream_open(inode, file);
200}
201
202static int acq_close(struct inode *inode, struct file *file)
203{
204 if (expect_close == 42) {
205 acq_stop();
206 } else {
207 pr_crit("Unexpected close, not stopping watchdog!\n");
208 acq_keepalive();
209 }
210 clear_bit(0, &acq_is_open);
211 expect_close = 0;
212 return 0;
213}
214
215/*
216 * Kernel Interfaces
217 */
218
219static const struct file_operations acq_fops = {
220 .owner = THIS_MODULE,
221 .llseek = no_llseek,
222 .write = acq_write,
223 .unlocked_ioctl = acq_ioctl,
224 .open = acq_open,
225 .release = acq_close,
226};
227
228static struct miscdevice acq_miscdev = {
229 .minor = WATCHDOG_MINOR,
230 .name = "watchdog",
231 .fops = &acq_fops,
232};
233
234/*
235 * Init & exit routines
236 */
237
238static int __init acq_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", wdt_stop);
245 ret = -EIO;
246 goto out;
247 }
248 }
249
250 if (!request_region(wdt_start, 1, WATCHDOG_NAME)) {
251 pr_err("I/O address 0x%04x already in use\n", wdt_start);
252 ret = -EIO;
253 goto unreg_stop;
254 }
255 ret = misc_register(&acq_miscdev);
256 if (ret != 0) {
257 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
258 WATCHDOG_MINOR, ret);
259 goto unreg_regions;
260 }
261 pr_info("initialized. (nowayout=%d)\n", nowayout);
262
263 return 0;
264unreg_regions:
265 release_region(wdt_start, 1);
266unreg_stop:
267 if (wdt_stop != wdt_start)
268 release_region(wdt_stop, 1);
269out:
270 return ret;
271}
272
273static int acq_remove(struct platform_device *dev)
274{
275 misc_deregister(&acq_miscdev);
276 release_region(wdt_start, 1);
277 if (wdt_stop != wdt_start)
278 release_region(wdt_stop, 1);
279
280 return 0;
281}
282
283static void acq_shutdown(struct platform_device *dev)
284{
285 /* Turn the WDT off if we have a soft shutdown */
286 acq_stop();
287}
288
289static struct platform_driver acquirewdt_driver = {
290 .remove = acq_remove,
291 .shutdown = acq_shutdown,
292 .driver = {
293 .name = DRV_NAME,
294 },
295};
296
297static int __init acq_init(void)
298{
299 int err;
300
301 pr_info("WDT driver for Acquire single board computer initialising\n");
302
303 acq_platform_device = platform_device_register_simple(DRV_NAME,
304 -1, NULL, 0);
305 if (IS_ERR(acq_platform_device))
306 return PTR_ERR(acq_platform_device);
307
308 err = platform_driver_probe(&acquirewdt_driver, acq_probe);
309 if (err)
310 goto unreg_platform_device;
311 return 0;
312
313unreg_platform_device:
314 platform_device_unregister(acq_platform_device);
315 return err;
316}
317
318static void __exit acq_exit(void)
319{
320 platform_device_unregister(acq_platform_device);
321 platform_driver_unregister(&acquirewdt_driver);
322 pr_info("Watchdog Module Unloaded\n");
323}
324
325module_init(acq_init);
326module_exit(acq_exit);
327
328MODULE_AUTHOR("David Woodhouse");
329MODULE_DESCRIPTION("Acquire Inc. Single Board Computer Watchdog Timer driver");
330MODULE_LICENSE("GPL");