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1/* drivers/char/watchdog/scx200_wdt.c
2
3 National Semiconductor SCx200 Watchdog support
4
5 Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com>
6
7 Some code taken from:
8 National Semiconductor PC87307/PC97307 (ala SC1200) WDT driver
9 (c) Copyright 2002 Zwane Mwaikambo <zwane@commfireservices.com>
10
11 This program is free software; you can redistribute it and/or
12 modify it under the terms of the GNU General Public License as
13 published by the Free Software Foundation; either version 2 of the
14 License, or (at your option) any later version.
15
16 The author(s) of this software shall not be held liable for damages
17 of any nature resulting due to the use of this software. This
18 software is provided AS-IS with no warranties. */
19
20#include <linux/module.h>
21#include <linux/moduleparam.h>
22#include <linux/init.h>
23#include <linux/miscdevice.h>
24#include <linux/watchdog.h>
25#include <linux/notifier.h>
26#include <linux/reboot.h>
27#include <linux/fs.h>
28#include <linux/ioport.h>
29#include <linux/scx200.h>
30#include <linux/uaccess.h>
31#include <linux/io.h>
32
33#define NAME "scx200_wdt"
34
35MODULE_AUTHOR("Christer Weinigel <wingel@nano-system.com>");
36MODULE_DESCRIPTION("NatSemi SCx200 Watchdog Driver");
37MODULE_LICENSE("GPL");
38MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
39
40static int margin = 60; /* in seconds */
41module_param(margin, int, 0);
42MODULE_PARM_DESC(margin, "Watchdog margin in seconds");
43
44static int nowayout = WATCHDOG_NOWAYOUT;
45module_param(nowayout, int, 0);
46MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
47
48static u16 wdto_restart;
49static char expect_close;
50static unsigned long open_lock;
51static DEFINE_SPINLOCK(scx_lock);
52
53/* Bits of the WDCNFG register */
54#define W_ENABLE 0x00fa /* Enable watchdog */
55#define W_DISABLE 0x0000 /* Disable watchdog */
56
57/* The scaling factor for the timer, this depends on the value of W_ENABLE */
58#define W_SCALE (32768/1024)
59
60static void scx200_wdt_ping(void)
61{
62 spin_lock(&scx_lock);
63 outw(wdto_restart, scx200_cb_base + SCx200_WDT_WDTO);
64 spin_unlock(&scx_lock);
65}
66
67static void scx200_wdt_update_margin(void)
68{
69 printk(KERN_INFO NAME ": timer margin %d seconds\n", margin);
70 wdto_restart = margin * W_SCALE;
71}
72
73static void scx200_wdt_enable(void)
74{
75 printk(KERN_DEBUG NAME ": enabling watchdog timer, wdto_restart = %d\n",
76 wdto_restart);
77
78 spin_lock(&scx_lock);
79 outw(0, scx200_cb_base + SCx200_WDT_WDTO);
80 outb(SCx200_WDT_WDSTS_WDOVF, scx200_cb_base + SCx200_WDT_WDSTS);
81 outw(W_ENABLE, scx200_cb_base + SCx200_WDT_WDCNFG);
82 spin_unlock(&scx_lock);
83
84 scx200_wdt_ping();
85}
86
87static void scx200_wdt_disable(void)
88{
89 printk(KERN_DEBUG NAME ": disabling watchdog timer\n");
90
91 spin_lock(&scx_lock);
92 outw(0, scx200_cb_base + SCx200_WDT_WDTO);
93 outb(SCx200_WDT_WDSTS_WDOVF, scx200_cb_base + SCx200_WDT_WDSTS);
94 outw(W_DISABLE, scx200_cb_base + SCx200_WDT_WDCNFG);
95 spin_unlock(&scx_lock);
96}
97
98static int scx200_wdt_open(struct inode *inode, struct file *file)
99{
100 /* only allow one at a time */
101 if (test_and_set_bit(0, &open_lock))
102 return -EBUSY;
103 scx200_wdt_enable();
104
105 return nonseekable_open(inode, file);
106}
107
108static int scx200_wdt_release(struct inode *inode, struct file *file)
109{
110 if (expect_close != 42)
111 printk(KERN_WARNING NAME
112 ": watchdog device closed unexpectedly, "
113 "will not disable the watchdog timer\n");
114 else if (!nowayout)
115 scx200_wdt_disable();
116 expect_close = 0;
117 clear_bit(0, &open_lock);
118
119 return 0;
120}
121
122static int scx200_wdt_notify_sys(struct notifier_block *this,
123 unsigned long code, void *unused)
124{
125 if (code == SYS_HALT || code == SYS_POWER_OFF)
126 if (!nowayout)
127 scx200_wdt_disable();
128
129 return NOTIFY_DONE;
130}
131
132static struct notifier_block scx200_wdt_notifier = {
133 .notifier_call = scx200_wdt_notify_sys,
134};
135
136static ssize_t scx200_wdt_write(struct file *file, const char __user *data,
137 size_t len, loff_t *ppos)
138{
139 /* check for a magic close character */
140 if (len) {
141 size_t i;
142
143 scx200_wdt_ping();
144
145 expect_close = 0;
146 for (i = 0; i < len; ++i) {
147 char c;
148 if (get_user(c, data + i))
149 return -EFAULT;
150 if (c == 'V')
151 expect_close = 42;
152 }
153
154 return len;
155 }
156
157 return 0;
158}
159
160static long scx200_wdt_ioctl(struct file *file, unsigned int cmd,
161 unsigned long arg)
162{
163 void __user *argp = (void __user *)arg;
164 int __user *p = argp;
165 static const struct watchdog_info ident = {
166 .identity = "NatSemi SCx200 Watchdog",
167 .firmware_version = 1,
168 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
169 WDIOF_MAGICCLOSE,
170 };
171 int new_margin;
172
173 switch (cmd) {
174 case WDIOC_GETSUPPORT:
175 if (copy_to_user(argp, &ident, sizeof(ident)))
176 return -EFAULT;
177 return 0;
178 case WDIOC_GETSTATUS:
179 case WDIOC_GETBOOTSTATUS:
180 if (put_user(0, p))
181 return -EFAULT;
182 return 0;
183 case WDIOC_KEEPALIVE:
184 scx200_wdt_ping();
185 return 0;
186 case WDIOC_SETTIMEOUT:
187 if (get_user(new_margin, p))
188 return -EFAULT;
189 if (new_margin < 1)
190 return -EINVAL;
191 margin = new_margin;
192 scx200_wdt_update_margin();
193 scx200_wdt_ping();
194 case WDIOC_GETTIMEOUT:
195 if (put_user(margin, p))
196 return -EFAULT;
197 return 0;
198 default:
199 return -ENOTTY;
200 }
201}
202
203static const struct file_operations scx200_wdt_fops = {
204 .owner = THIS_MODULE,
205 .llseek = no_llseek,
206 .write = scx200_wdt_write,
207 .unlocked_ioctl = scx200_wdt_ioctl,
208 .open = scx200_wdt_open,
209 .release = scx200_wdt_release,
210};
211
212static struct miscdevice scx200_wdt_miscdev = {
213 .minor = WATCHDOG_MINOR,
214 .name = "watchdog",
215 .fops = &scx200_wdt_fops,
216};
217
218static int __init scx200_wdt_init(void)
219{
220 int r;
221
222 printk(KERN_DEBUG NAME ": NatSemi SCx200 Watchdog Driver\n");
223
224 /* check that we have found the configuration block */
225 if (!scx200_cb_present())
226 return -ENODEV;
227
228 if (!request_region(scx200_cb_base + SCx200_WDT_OFFSET,
229 SCx200_WDT_SIZE,
230 "NatSemi SCx200 Watchdog")) {
231 printk(KERN_WARNING NAME ": watchdog I/O region busy\n");
232 return -EBUSY;
233 }
234
235 scx200_wdt_update_margin();
236 scx200_wdt_disable();
237
238 r = register_reboot_notifier(&scx200_wdt_notifier);
239 if (r) {
240 printk(KERN_ERR NAME ": unable to register reboot notifier");
241 release_region(scx200_cb_base + SCx200_WDT_OFFSET,
242 SCx200_WDT_SIZE);
243 return r;
244 }
245
246 r = misc_register(&scx200_wdt_miscdev);
247 if (r) {
248 unregister_reboot_notifier(&scx200_wdt_notifier);
249 release_region(scx200_cb_base + SCx200_WDT_OFFSET,
250 SCx200_WDT_SIZE);
251 return r;
252 }
253
254 return 0;
255}
256
257static void __exit scx200_wdt_cleanup(void)
258{
259 misc_deregister(&scx200_wdt_miscdev);
260 unregister_reboot_notifier(&scx200_wdt_notifier);
261 release_region(scx200_cb_base + SCx200_WDT_OFFSET,
262 SCx200_WDT_SIZE);
263}
264
265module_init(scx200_wdt_init);
266module_exit(scx200_wdt_cleanup);
267
268/*
269 Local variables:
270 compile-command: "make -k -C ../.. SUBDIRS=drivers/char modules"
271 c-basic-offset: 8
272 End:
273*/
1// SPDX-License-Identifier: GPL-2.0-or-later
2/* drivers/char/watchdog/scx200_wdt.c
3
4 National Semiconductor SCx200 Watchdog support
5
6 Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com>
7
8 Some code taken from:
9 National Semiconductor PC87307/PC97307 (ala SC1200) WDT driver
10 (c) Copyright 2002 Zwane Mwaikambo <zwane@commfireservices.com>
11
12
13 The author(s) of this software shall not be held liable for damages
14 of any nature resulting due to the use of this software. This
15 software is provided AS-IS with no warranties. */
16
17#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
18
19#include <linux/module.h>
20#include <linux/moduleparam.h>
21#include <linux/init.h>
22#include <linux/miscdevice.h>
23#include <linux/watchdog.h>
24#include <linux/notifier.h>
25#include <linux/reboot.h>
26#include <linux/fs.h>
27#include <linux/ioport.h>
28#include <linux/scx200.h>
29#include <linux/uaccess.h>
30#include <linux/io.h>
31
32#define DEBUG
33
34MODULE_AUTHOR("Christer Weinigel <wingel@nano-system.com>");
35MODULE_DESCRIPTION("NatSemi SCx200 Watchdog Driver");
36MODULE_LICENSE("GPL");
37
38static int margin = 60; /* in seconds */
39module_param(margin, int, 0);
40MODULE_PARM_DESC(margin, "Watchdog margin in seconds");
41
42static bool nowayout = WATCHDOG_NOWAYOUT;
43module_param(nowayout, bool, 0);
44MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
45
46static u16 wdto_restart;
47static char expect_close;
48static unsigned long open_lock;
49static DEFINE_SPINLOCK(scx_lock);
50
51/* Bits of the WDCNFG register */
52#define W_ENABLE 0x00fa /* Enable watchdog */
53#define W_DISABLE 0x0000 /* Disable watchdog */
54
55/* The scaling factor for the timer, this depends on the value of W_ENABLE */
56#define W_SCALE (32768/1024)
57
58static void scx200_wdt_ping(void)
59{
60 spin_lock(&scx_lock);
61 outw(wdto_restart, scx200_cb_base + SCx200_WDT_WDTO);
62 spin_unlock(&scx_lock);
63}
64
65static void scx200_wdt_update_margin(void)
66{
67 pr_info("timer margin %d seconds\n", margin);
68 wdto_restart = margin * W_SCALE;
69}
70
71static void scx200_wdt_enable(void)
72{
73 pr_debug("enabling watchdog timer, wdto_restart = %d\n", wdto_restart);
74
75 spin_lock(&scx_lock);
76 outw(0, scx200_cb_base + SCx200_WDT_WDTO);
77 outb(SCx200_WDT_WDSTS_WDOVF, scx200_cb_base + SCx200_WDT_WDSTS);
78 outw(W_ENABLE, scx200_cb_base + SCx200_WDT_WDCNFG);
79 spin_unlock(&scx_lock);
80
81 scx200_wdt_ping();
82}
83
84static void scx200_wdt_disable(void)
85{
86 pr_debug("disabling watchdog timer\n");
87
88 spin_lock(&scx_lock);
89 outw(0, scx200_cb_base + SCx200_WDT_WDTO);
90 outb(SCx200_WDT_WDSTS_WDOVF, scx200_cb_base + SCx200_WDT_WDSTS);
91 outw(W_DISABLE, scx200_cb_base + SCx200_WDT_WDCNFG);
92 spin_unlock(&scx_lock);
93}
94
95static int scx200_wdt_open(struct inode *inode, struct file *file)
96{
97 /* only allow one at a time */
98 if (test_and_set_bit(0, &open_lock))
99 return -EBUSY;
100 scx200_wdt_enable();
101
102 return stream_open(inode, file);
103}
104
105static int scx200_wdt_release(struct inode *inode, struct file *file)
106{
107 if (expect_close != 42)
108 pr_warn("watchdog device closed unexpectedly, will not disable the watchdog timer\n");
109 else if (!nowayout)
110 scx200_wdt_disable();
111 expect_close = 0;
112 clear_bit(0, &open_lock);
113
114 return 0;
115}
116
117static int scx200_wdt_notify_sys(struct notifier_block *this,
118 unsigned long code, void *unused)
119{
120 if (code == SYS_HALT || code == SYS_POWER_OFF)
121 if (!nowayout)
122 scx200_wdt_disable();
123
124 return NOTIFY_DONE;
125}
126
127static struct notifier_block scx200_wdt_notifier = {
128 .notifier_call = scx200_wdt_notify_sys,
129};
130
131static ssize_t scx200_wdt_write(struct file *file, const char __user *data,
132 size_t len, loff_t *ppos)
133{
134 /* check for a magic close character */
135 if (len) {
136 size_t i;
137
138 scx200_wdt_ping();
139
140 expect_close = 0;
141 for (i = 0; i < len; ++i) {
142 char c;
143 if (get_user(c, data + i))
144 return -EFAULT;
145 if (c == 'V')
146 expect_close = 42;
147 }
148
149 return len;
150 }
151
152 return 0;
153}
154
155static long scx200_wdt_ioctl(struct file *file, unsigned int cmd,
156 unsigned long arg)
157{
158 void __user *argp = (void __user *)arg;
159 int __user *p = argp;
160 static const struct watchdog_info ident = {
161 .identity = "NatSemi SCx200 Watchdog",
162 .firmware_version = 1,
163 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
164 WDIOF_MAGICCLOSE,
165 };
166 int new_margin;
167
168 switch (cmd) {
169 case WDIOC_GETSUPPORT:
170 if (copy_to_user(argp, &ident, sizeof(ident)))
171 return -EFAULT;
172 return 0;
173 case WDIOC_GETSTATUS:
174 case WDIOC_GETBOOTSTATUS:
175 if (put_user(0, p))
176 return -EFAULT;
177 return 0;
178 case WDIOC_KEEPALIVE:
179 scx200_wdt_ping();
180 return 0;
181 case WDIOC_SETTIMEOUT:
182 if (get_user(new_margin, p))
183 return -EFAULT;
184 if (new_margin < 1)
185 return -EINVAL;
186 margin = new_margin;
187 scx200_wdt_update_margin();
188 scx200_wdt_ping();
189 fallthrough;
190 case WDIOC_GETTIMEOUT:
191 if (put_user(margin, p))
192 return -EFAULT;
193 return 0;
194 default:
195 return -ENOTTY;
196 }
197}
198
199static const struct file_operations scx200_wdt_fops = {
200 .owner = THIS_MODULE,
201 .llseek = no_llseek,
202 .write = scx200_wdt_write,
203 .unlocked_ioctl = scx200_wdt_ioctl,
204 .compat_ioctl = compat_ptr_ioctl,
205 .open = scx200_wdt_open,
206 .release = scx200_wdt_release,
207};
208
209static struct miscdevice scx200_wdt_miscdev = {
210 .minor = WATCHDOG_MINOR,
211 .name = "watchdog",
212 .fops = &scx200_wdt_fops,
213};
214
215static int __init scx200_wdt_init(void)
216{
217 int r;
218
219 pr_debug("NatSemi SCx200 Watchdog Driver\n");
220
221 /* check that we have found the configuration block */
222 if (!scx200_cb_present())
223 return -ENODEV;
224
225 if (!request_region(scx200_cb_base + SCx200_WDT_OFFSET,
226 SCx200_WDT_SIZE,
227 "NatSemi SCx200 Watchdog")) {
228 pr_warn("watchdog I/O region busy\n");
229 return -EBUSY;
230 }
231
232 scx200_wdt_update_margin();
233 scx200_wdt_disable();
234
235 r = register_reboot_notifier(&scx200_wdt_notifier);
236 if (r) {
237 pr_err("unable to register reboot notifier\n");
238 release_region(scx200_cb_base + SCx200_WDT_OFFSET,
239 SCx200_WDT_SIZE);
240 return r;
241 }
242
243 r = misc_register(&scx200_wdt_miscdev);
244 if (r) {
245 unregister_reboot_notifier(&scx200_wdt_notifier);
246 release_region(scx200_cb_base + SCx200_WDT_OFFSET,
247 SCx200_WDT_SIZE);
248 return r;
249 }
250
251 return 0;
252}
253
254static void __exit scx200_wdt_cleanup(void)
255{
256 misc_deregister(&scx200_wdt_miscdev);
257 unregister_reboot_notifier(&scx200_wdt_notifier);
258 release_region(scx200_cb_base + SCx200_WDT_OFFSET,
259 SCx200_WDT_SIZE);
260}
261
262module_init(scx200_wdt_init);
263module_exit(scx200_wdt_cleanup);