1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * IndyDog 0.3 A Hardware Watchdog Device for SGI IP22
4 *
5 * (c) Copyright 2002 Guido Guenther <agx@sigxcpu.org>,
6 * All Rights Reserved.
7 *
8 * based on softdog.c by Alan Cox <alan@lxorguk.ukuu.org.uk>
9 */
10
11 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
12
13 #include <linux/module.h>
14 #include <linux/moduleparam.h>
15 #include <linux/types.h>
16 #include <linux/kernel.h>
17 #include <linux/fs.h>
18 #include <linux/mm.h>
19 #include <linux/miscdevice.h>
20 #include <linux/watchdog.h>
21 #include <linux/notifier.h>
22 #include <linux/reboot.h>
23 #include <linux/init.h>
24 #include <linux/uaccess.h>
25 #include <asm/sgi/mc.h>
26
27 static unsigned long indydog_alive;
28 static DEFINE_SPINLOCK(indydog_lock);
29
30 #define WATCHDOG_TIMEOUT 30 /* 30 sec default timeout */
31
32 static bool nowayout = WATCHDOG_NOWAYOUT;
33 module_param(nowayout, bool, 0);
34 MODULE_PARM_DESC(nowayout,
35 "Watchdog cannot be stopped once started (default="
36 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
37
indydog_start(void)38 static void indydog_start(void)
39 {
40 spin_lock(&indydog_lock);
41 sgimc->cpuctrl0 |= SGIMC_CCTRL0_WDOG;
42 spin_unlock(&indydog_lock);
43 }
44
indydog_stop(void)45 static void indydog_stop(void)
46 {
47 spin_lock(&indydog_lock);
48 sgimc->cpuctrl0 &= ~SGIMC_CCTRL0_WDOG;
49 spin_unlock(&indydog_lock);
50
51 pr_info("Stopped watchdog timer\n");
52 }
53
indydog_ping(void)54 static void indydog_ping(void)
55 {
56 sgimc->watchdogt = 0;
57 }
58
59 /*
60 * Allow only one person to hold it open
61 */
indydog_open(struct inode * inode,struct file * file)62 static int indydog_open(struct inode *inode, struct file *file)
63 {
64 if (test_and_set_bit(0, &indydog_alive))
65 return -EBUSY;
66
67 if (nowayout)
68 __module_get(THIS_MODULE);
69
70 /* Activate timer */
71 indydog_start();
72 indydog_ping();
73
74 pr_info("Started watchdog timer\n");
75
76 return stream_open(inode, file);
77 }
78
indydog_release(struct inode * inode,struct file * file)79 static int indydog_release(struct inode *inode, struct file *file)
80 {
81 /* Shut off the timer.
82 * Lock it in if it's a module and we defined ...NOWAYOUT */
83 if (!nowayout)
84 indydog_stop(); /* Turn the WDT off */
85 clear_bit(0, &indydog_alive);
86 return 0;
87 }
88
indydog_write(struct file * file,const char * data,size_t len,loff_t * ppos)89 static ssize_t indydog_write(struct file *file, const char *data,
90 size_t len, loff_t *ppos)
91 {
92 /* Refresh the timer. */
93 if (len)
94 indydog_ping();
95 return len;
96 }
97
indydog_ioctl(struct file * file,unsigned int cmd,unsigned long arg)98 static long indydog_ioctl(struct file *file, unsigned int cmd,
99 unsigned long arg)
100 {
101 int options, retval = -EINVAL;
102 static const struct watchdog_info ident = {
103 .options = WDIOF_KEEPALIVEPING,
104 .firmware_version = 0,
105 .identity = "Hardware Watchdog for SGI IP22",
106 };
107
108 switch (cmd) {
109 case WDIOC_GETSUPPORT:
110 if (copy_to_user((struct watchdog_info *)arg,
111 &ident, sizeof(ident)))
112 return -EFAULT;
113 return 0;
114 case WDIOC_GETSTATUS:
115 case WDIOC_GETBOOTSTATUS:
116 return put_user(0, (int *)arg);
117 case WDIOC_SETOPTIONS:
118 {
119 if (get_user(options, (int *)arg))
120 return -EFAULT;
121 if (options & WDIOS_DISABLECARD) {
122 indydog_stop();
123 retval = 0;
124 }
125 if (options & WDIOS_ENABLECARD) {
126 indydog_start();
127 retval = 0;
128 }
129 return retval;
130 }
131 case WDIOC_KEEPALIVE:
132 indydog_ping();
133 return 0;
134 case WDIOC_GETTIMEOUT:
135 return put_user(WATCHDOG_TIMEOUT, (int *)arg);
136 default:
137 return -ENOTTY;
138 }
139 }
140
indydog_notify_sys(struct notifier_block * this,unsigned long code,void * unused)141 static int indydog_notify_sys(struct notifier_block *this,
142 unsigned long code, void *unused)
143 {
144 if (code == SYS_DOWN || code == SYS_HALT)
145 indydog_stop(); /* Turn the WDT off */
146
147 return NOTIFY_DONE;
148 }
149
150 static const struct file_operations indydog_fops = {
151 .owner = THIS_MODULE,
152 .llseek = no_llseek,
153 .write = indydog_write,
154 .unlocked_ioctl = indydog_ioctl,
155 .open = indydog_open,
156 .release = indydog_release,
157 };
158
159 static struct miscdevice indydog_miscdev = {
160 .minor = WATCHDOG_MINOR,
161 .name = "watchdog",
162 .fops = &indydog_fops,
163 };
164
165 static struct notifier_block indydog_notifier = {
166 .notifier_call = indydog_notify_sys,
167 };
168
watchdog_init(void)169 static int __init watchdog_init(void)
170 {
171 int ret;
172
173 ret = register_reboot_notifier(&indydog_notifier);
174 if (ret) {
175 pr_err("cannot register reboot notifier (err=%d)\n", ret);
176 return ret;
177 }
178
179 ret = misc_register(&indydog_miscdev);
180 if (ret) {
181 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
182 WATCHDOG_MINOR, ret);
183 unregister_reboot_notifier(&indydog_notifier);
184 return ret;
185 }
186
187 pr_info("Hardware Watchdog Timer for SGI IP22: 0.3\n");
188
189 return 0;
190 }
191
watchdog_exit(void)192 static void __exit watchdog_exit(void)
193 {
194 misc_deregister(&indydog_miscdev);
195 unregister_reboot_notifier(&indydog_notifier);
196 }
197
198 module_init(watchdog_init);
199 module_exit(watchdog_exit);
200
201 MODULE_AUTHOR("Guido Guenther <agx@sigxcpu.org>");
202 MODULE_DESCRIPTION("Hardware Watchdog Device for SGI IP22");
203 MODULE_LICENSE("GPL");
204
