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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);
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
21
22#include <linux/module.h>
23#include <linux/moduleparam.h>
24#include <linux/init.h>
25#include <linux/miscdevice.h>
26#include <linux/watchdog.h>
27#include <linux/notifier.h>
28#include <linux/reboot.h>
29#include <linux/fs.h>
30#include <linux/ioport.h>
31#include <linux/scx200.h>
32#include <linux/uaccess.h>
33#include <linux/io.h>
34
35#define DEBUG
36
37MODULE_AUTHOR("Christer Weinigel <wingel@nano-system.com>");
38MODULE_DESCRIPTION("NatSemi SCx200 Watchdog Driver");
39MODULE_LICENSE("GPL");
40MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
41
42static int margin = 60; /* in seconds */
43module_param(margin, int, 0);
44MODULE_PARM_DESC(margin, "Watchdog margin in seconds");
45
46static bool nowayout = WATCHDOG_NOWAYOUT;
47module_param(nowayout, bool, 0);
48MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
49
50static u16 wdto_restart;
51static char expect_close;
52static unsigned long open_lock;
53static DEFINE_SPINLOCK(scx_lock);
54
55/* Bits of the WDCNFG register */
56#define W_ENABLE 0x00fa /* Enable watchdog */
57#define W_DISABLE 0x0000 /* Disable watchdog */
58
59/* The scaling factor for the timer, this depends on the value of W_ENABLE */
60#define W_SCALE (32768/1024)
61
62static void scx200_wdt_ping(void)
63{
64 spin_lock(&scx_lock);
65 outw(wdto_restart, scx200_cb_base + SCx200_WDT_WDTO);
66 spin_unlock(&scx_lock);
67}
68
69static void scx200_wdt_update_margin(void)
70{
71 pr_info("timer margin %d seconds\n", margin);
72 wdto_restart = margin * W_SCALE;
73}
74
75static void scx200_wdt_enable(void)
76{
77 pr_debug("enabling watchdog timer, wdto_restart = %d\n", wdto_restart);
78
79 spin_lock(&scx_lock);
80 outw(0, scx200_cb_base + SCx200_WDT_WDTO);
81 outb(SCx200_WDT_WDSTS_WDOVF, scx200_cb_base + SCx200_WDT_WDSTS);
82 outw(W_ENABLE, scx200_cb_base + SCx200_WDT_WDCNFG);
83 spin_unlock(&scx_lock);
84
85 scx200_wdt_ping();
86}
87
88static void scx200_wdt_disable(void)
89{
90 pr_debug("disabling watchdog timer\n");
91
92 spin_lock(&scx_lock);
93 outw(0, scx200_cb_base + SCx200_WDT_WDTO);
94 outb(SCx200_WDT_WDSTS_WDOVF, scx200_cb_base + SCx200_WDT_WDSTS);
95 outw(W_DISABLE, scx200_cb_base + SCx200_WDT_WDCNFG);
96 spin_unlock(&scx_lock);
97}
98
99static int scx200_wdt_open(struct inode *inode, struct file *file)
100{
101 /* only allow one at a time */
102 if (test_and_set_bit(0, &open_lock))
103 return -EBUSY;
104 scx200_wdt_enable();
105
106 return nonseekable_open(inode, file);
107}
108
109static int scx200_wdt_release(struct inode *inode, struct file *file)
110{
111 if (expect_close != 42)
112 pr_warn("watchdog device closed unexpectedly, will not disable the watchdog timer\n");
113 else if (!nowayout)
114 scx200_wdt_disable();
115 expect_close = 0;
116 clear_bit(0, &open_lock);
117
118 return 0;
119}
120
121static int scx200_wdt_notify_sys(struct notifier_block *this,
122 unsigned long code, void *unused)
123{
124 if (code == SYS_HALT || code == SYS_POWER_OFF)
125 if (!nowayout)
126 scx200_wdt_disable();
127
128 return NOTIFY_DONE;
129}
130
131static struct notifier_block scx200_wdt_notifier = {
132 .notifier_call = scx200_wdt_notify_sys,
133};
134
135static ssize_t scx200_wdt_write(struct file *file, const char __user *data,
136 size_t len, loff_t *ppos)
137{
138 /* check for a magic close character */
139 if (len) {
140 size_t i;
141
142 scx200_wdt_ping();
143
144 expect_close = 0;
145 for (i = 0; i < len; ++i) {
146 char c;
147 if (get_user(c, data + i))
148 return -EFAULT;
149 if (c == 'V')
150 expect_close = 42;
151 }
152
153 return len;
154 }
155
156 return 0;
157}
158
159static long scx200_wdt_ioctl(struct file *file, unsigned int cmd,
160 unsigned long arg)
161{
162 void __user *argp = (void __user *)arg;
163 int __user *p = argp;
164 static const struct watchdog_info ident = {
165 .identity = "NatSemi SCx200 Watchdog",
166 .firmware_version = 1,
167 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
168 WDIOF_MAGICCLOSE,
169 };
170 int new_margin;
171
172 switch (cmd) {
173 case WDIOC_GETSUPPORT:
174 if (copy_to_user(argp, &ident, sizeof(ident)))
175 return -EFAULT;
176 return 0;
177 case WDIOC_GETSTATUS:
178 case WDIOC_GETBOOTSTATUS:
179 if (put_user(0, p))
180 return -EFAULT;
181 return 0;
182 case WDIOC_KEEPALIVE:
183 scx200_wdt_ping();
184 return 0;
185 case WDIOC_SETTIMEOUT:
186 if (get_user(new_margin, p))
187 return -EFAULT;
188 if (new_margin < 1)
189 return -EINVAL;
190 margin = new_margin;
191 scx200_wdt_update_margin();
192 scx200_wdt_ping();
193 case WDIOC_GETTIMEOUT:
194 if (put_user(margin, p))
195 return -EFAULT;
196 return 0;
197 default:
198 return -ENOTTY;
199 }
200}
201
202static const struct file_operations scx200_wdt_fops = {
203 .owner = THIS_MODULE,
204 .llseek = no_llseek,
205 .write = scx200_wdt_write,
206 .unlocked_ioctl = scx200_wdt_ioctl,
207 .open = scx200_wdt_open,
208 .release = scx200_wdt_release,
209};
210
211static struct miscdevice scx200_wdt_miscdev = {
212 .minor = WATCHDOG_MINOR,
213 .name = "watchdog",
214 .fops = &scx200_wdt_fops,
215};
216
217static int __init scx200_wdt_init(void)
218{
219 int r;
220
221 pr_debug("NatSemi SCx200 Watchdog Driver\n");
222
223 /* check that we have found the configuration block */
224 if (!scx200_cb_present())
225 return -ENODEV;
226
227 if (!request_region(scx200_cb_base + SCx200_WDT_OFFSET,
228 SCx200_WDT_SIZE,
229 "NatSemi SCx200 Watchdog")) {
230 pr_warn("watchdog I/O region busy\n");
231 return -EBUSY;
232 }
233
234 scx200_wdt_update_margin();
235 scx200_wdt_disable();
236
237 r = register_reboot_notifier(&scx200_wdt_notifier);
238 if (r) {
239 pr_err("unable to register reboot notifier\n");
240 release_region(scx200_cb_base + SCx200_WDT_OFFSET,
241 SCx200_WDT_SIZE);
242 return r;
243 }
244
245 r = misc_register(&scx200_wdt_miscdev);
246 if (r) {
247 unregister_reboot_notifier(&scx200_wdt_notifier);
248 release_region(scx200_cb_base + SCx200_WDT_OFFSET,
249 SCx200_WDT_SIZE);
250 return r;
251 }
252
253 return 0;
254}
255
256static void __exit scx200_wdt_cleanup(void)
257{
258 misc_deregister(&scx200_wdt_miscdev);
259 unregister_reboot_notifier(&scx200_wdt_notifier);
260 release_region(scx200_cb_base + SCx200_WDT_OFFSET,
261 SCx200_WDT_SIZE);
262}
263
264module_init(scx200_wdt_init);
265module_exit(scx200_wdt_cleanup);
266
267/*
268 Local variables:
269 compile-command: "make -k -C ../.. SUBDIRS=drivers/char modules"
270 c-basic-offset: 8
271 End:
272*/