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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 | #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 | |
37 | MODULE_AUTHOR("Christer Weinigel <wingel@nano-system.com>"); |
38 | MODULE_DESCRIPTION("NatSemi SCx200 Watchdog Driver"); |
39 | MODULE_LICENSE("GPL"); |
40 | MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); |
41 | |
42 | static int margin = 60; /* in seconds */ |
43 | module_param(margin, int, 0); |
44 | MODULE_PARM_DESC(margin, "Watchdog margin in seconds"); |
45 | |
46 | static bool nowayout = WATCHDOG_NOWAYOUT; |
47 | module_param(nowayout, bool, 0); |
48 | MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close"); |
49 | |
50 | static u16 wdto_restart; |
51 | static char expect_close; |
52 | static unsigned long open_lock; |
53 | static 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 | |
62 | static 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 | |
69 | static void scx200_wdt_update_margin(void) |
70 | { |
71 | pr_info("timer margin %d seconds\n", margin); |
72 | wdto_restart = margin * W_SCALE; |
73 | } |
74 | |
75 | static 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 | |
88 | static 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 | |
99 | static 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 | |
109 | static 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 | |
121 | static 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 | |
131 | static struct notifier_block scx200_wdt_notifier = { |
132 | .notifier_call = scx200_wdt_notify_sys, |
133 | }; |
134 | |
135 | static 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 | |
159 | static 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 | |
202 | static 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 | |
211 | static struct miscdevice scx200_wdt_miscdev = { |
212 | .minor = WATCHDOG_MINOR, |
213 | .name = "watchdog", |
214 | .fops = &scx200_wdt_fops, |
215 | }; |
216 | |
217 | static 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 | |
256 | static 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 | |
264 | module_init(scx200_wdt_init); |
265 | module_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 | */ |
273 |
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