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 | |
34 | MODULE_AUTHOR("Christer Weinigel <wingel@nano-system.com>" ); |
35 | MODULE_DESCRIPTION("NatSemi SCx200 Watchdog Driver" ); |
36 | MODULE_LICENSE("GPL" ); |
37 | |
38 | static int margin = 60; /* in seconds */ |
39 | module_param(margin, int, 0); |
40 | MODULE_PARM_DESC(margin, "Watchdog margin in seconds" ); |
41 | |
42 | static bool nowayout = WATCHDOG_NOWAYOUT; |
43 | module_param(nowayout, bool, 0); |
44 | MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close" ); |
45 | |
46 | static u16 wdto_restart; |
47 | static char expect_close; |
48 | static unsigned long open_lock; |
49 | static 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 | |
58 | static void scx200_wdt_ping(void) |
59 | { |
60 | spin_lock(lock: &scx_lock); |
61 | outw(value: wdto_restart, port: scx200_cb_base + SCx200_WDT_WDTO); |
62 | spin_unlock(lock: &scx_lock); |
63 | } |
64 | |
65 | static void scx200_wdt_update_margin(void) |
66 | { |
67 | pr_info("timer margin %d seconds\n" , margin); |
68 | wdto_restart = margin * W_SCALE; |
69 | } |
70 | |
71 | static void scx200_wdt_enable(void) |
72 | { |
73 | pr_debug("enabling watchdog timer, wdto_restart = %d\n" , wdto_restart); |
74 | |
75 | spin_lock(lock: &scx_lock); |
76 | outw(value: 0, port: scx200_cb_base + SCx200_WDT_WDTO); |
77 | outb(SCx200_WDT_WDSTS_WDOVF, port: scx200_cb_base + SCx200_WDT_WDSTS); |
78 | outw(W_ENABLE, port: scx200_cb_base + SCx200_WDT_WDCNFG); |
79 | spin_unlock(lock: &scx_lock); |
80 | |
81 | scx200_wdt_ping(); |
82 | } |
83 | |
84 | static void scx200_wdt_disable(void) |
85 | { |
86 | pr_debug("disabling watchdog timer\n" ); |
87 | |
88 | spin_lock(lock: &scx_lock); |
89 | outw(value: 0, port: scx200_cb_base + SCx200_WDT_WDTO); |
90 | outb(SCx200_WDT_WDSTS_WDOVF, port: scx200_cb_base + SCx200_WDT_WDSTS); |
91 | outw(W_DISABLE, port: scx200_cb_base + SCx200_WDT_WDCNFG); |
92 | spin_unlock(lock: &scx_lock); |
93 | } |
94 | |
95 | static int scx200_wdt_open(struct inode *inode, struct file *file) |
96 | { |
97 | /* only allow one at a time */ |
98 | if (test_and_set_bit(nr: 0, addr: &open_lock)) |
99 | return -EBUSY; |
100 | scx200_wdt_enable(); |
101 | |
102 | return stream_open(inode, filp: file); |
103 | } |
104 | |
105 | static 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(nr: 0, addr: &open_lock); |
113 | |
114 | return 0; |
115 | } |
116 | |
117 | static 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 | |
127 | static struct notifier_block scx200_wdt_notifier = { |
128 | .notifier_call = scx200_wdt_notify_sys, |
129 | }; |
130 | |
131 | static 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 | |
155 | static 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(to: argp, from: &ident, n: 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 | |
199 | static 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 | |
209 | static struct miscdevice scx200_wdt_miscdev = { |
210 | .minor = WATCHDOG_MINOR, |
211 | .name = "watchdog" , |
212 | .fops = &scx200_wdt_fops, |
213 | }; |
214 | |
215 | static 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(misc: &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 | |
254 | static void __exit scx200_wdt_cleanup(void) |
255 | { |
256 | misc_deregister(misc: &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 | |
262 | module_init(scx200_wdt_init); |
263 | module_exit(scx200_wdt_cleanup); |
264 | |