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