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 | |
38 | static void indydog_start(void) |
39 | { |
40 | spin_lock(lock: &indydog_lock); |
41 | sgimc->cpuctrl0 |= SGIMC_CCTRL0_WDOG; |
42 | spin_unlock(lock: &indydog_lock); |
43 | } |
44 | |
45 | static void indydog_stop(void) |
46 | { |
47 | spin_lock(lock: &indydog_lock); |
48 | sgimc->cpuctrl0 &= ~SGIMC_CCTRL0_WDOG; |
49 | spin_unlock(lock: &indydog_lock); |
50 | |
51 | pr_info("Stopped watchdog timer\n" ); |
52 | } |
53 | |
54 | static void indydog_ping(void) |
55 | { |
56 | sgimc->watchdogt = 0; |
57 | } |
58 | |
59 | /* |
60 | * Allow only one person to hold it open |
61 | */ |
62 | static int indydog_open(struct inode *inode, struct file *file) |
63 | { |
64 | if (test_and_set_bit(nr: 0, addr: &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, filp: file); |
77 | } |
78 | |
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(nr: 0, addr: &indydog_alive); |
86 | return 0; |
87 | } |
88 | |
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 | |
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(to: (struct watchdog_info *)arg, |
111 | from: &ident, n: 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 | |
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 | .compat_ioctl = compat_ptr_ioctl, |
156 | .open = indydog_open, |
157 | .release = indydog_release, |
158 | }; |
159 | |
160 | static struct miscdevice indydog_miscdev = { |
161 | .minor = WATCHDOG_MINOR, |
162 | .name = "watchdog" , |
163 | .fops = &indydog_fops, |
164 | }; |
165 | |
166 | static struct notifier_block indydog_notifier = { |
167 | .notifier_call = indydog_notify_sys, |
168 | }; |
169 | |
170 | static int __init watchdog_init(void) |
171 | { |
172 | int ret; |
173 | |
174 | ret = register_reboot_notifier(&indydog_notifier); |
175 | if (ret) { |
176 | pr_err("cannot register reboot notifier (err=%d)\n" , ret); |
177 | return ret; |
178 | } |
179 | |
180 | ret = misc_register(misc: &indydog_miscdev); |
181 | if (ret) { |
182 | pr_err("cannot register miscdev on minor=%d (err=%d)\n" , |
183 | WATCHDOG_MINOR, ret); |
184 | unregister_reboot_notifier(&indydog_notifier); |
185 | return ret; |
186 | } |
187 | |
188 | pr_info("Hardware Watchdog Timer for SGI IP22: 0.3\n" ); |
189 | |
190 | return 0; |
191 | } |
192 | |
193 | static void __exit watchdog_exit(void) |
194 | { |
195 | misc_deregister(misc: &indydog_miscdev); |
196 | unregister_reboot_notifier(&indydog_notifier); |
197 | } |
198 | |
199 | module_init(watchdog_init); |
200 | module_exit(watchdog_exit); |
201 | |
202 | MODULE_AUTHOR("Guido Guenther <agx@sigxcpu.org>" ); |
203 | MODULE_DESCRIPTION("Hardware Watchdog Device for SGI IP22" ); |
204 | MODULE_LICENSE("GPL" ); |
205 | |