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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;
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
52#define W_ENABLE 0x00fa
53#define W_DISABLE 0x0000
54
55
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
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
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
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);
264
