Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * Watchdog implementation based on z/VM Watchdog Timer API | |
3 | * | |
58872d5f CB |
4 | * Copyright IBM Corp. 2004,2009 |
5 | * | |
1da177e4 LT |
6 | * The user space watchdog daemon can use this driver as |
7 | * /dev/vmwatchdog to have z/VM execute the specified CP | |
8 | * command when the timeout expires. The default command is | |
9 | * "IPL", which which cause an immediate reboot. | |
10 | */ | |
58872d5f CB |
11 | #define KMSG_COMPONENT "vmwatchdog" |
12 | #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt | |
13 | ||
1da177e4 LT |
14 | #include <linux/init.h> |
15 | #include <linux/fs.h> | |
16 | #include <linux/kernel.h> | |
17 | #include <linux/miscdevice.h> | |
18 | #include <linux/module.h> | |
19 | #include <linux/moduleparam.h> | |
58872d5f | 20 | #include <linux/suspend.h> |
1da177e4 | 21 | #include <linux/watchdog.h> |
3e0420f0 | 22 | #include <linux/smp_lock.h> |
1da177e4 LT |
23 | |
24 | #include <asm/ebcdic.h> | |
25 | #include <asm/io.h> | |
26 | #include <asm/uaccess.h> | |
27 | ||
28 | #define MAX_CMDLEN 240 | |
29 | #define MIN_INTERVAL 15 | |
30 | static char vmwdt_cmd[MAX_CMDLEN] = "IPL"; | |
31 | static int vmwdt_conceal; | |
32 | ||
4bfdf378 | 33 | static int vmwdt_nowayout = WATCHDOG_NOWAYOUT; |
1da177e4 LT |
34 | |
35 | MODULE_LICENSE("GPL"); | |
36 | MODULE_AUTHOR("Arnd Bergmann <arndb@de.ibm.com>"); | |
37 | MODULE_DESCRIPTION("z/VM Watchdog Timer"); | |
38 | module_param_string(cmd, vmwdt_cmd, MAX_CMDLEN, 0644); | |
39 | MODULE_PARM_DESC(cmd, "CP command that is run when the watchdog triggers"); | |
40 | module_param_named(conceal, vmwdt_conceal, bool, 0644); | |
41 | MODULE_PARM_DESC(conceal, "Enable the CONCEAL CP option while the watchdog " | |
42 | " is active"); | |
43 | module_param_named(nowayout, vmwdt_nowayout, bool, 0); | |
44 | MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started" | |
45 | " (default=CONFIG_WATCHDOG_NOWAYOUT)"); | |
46 | MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); | |
47 | ||
48 | static unsigned int vmwdt_interval = 60; | |
49 | static unsigned long vmwdt_is_open; | |
50 | static int vmwdt_expect_close; | |
51 | ||
58872d5f CB |
52 | #define VMWDT_OPEN 0 /* devnode is open or suspend in progress */ |
53 | #define VMWDT_RUNNING 1 /* The watchdog is armed */ | |
54 | ||
1da177e4 LT |
55 | enum vmwdt_func { |
56 | /* function codes */ | |
57 | wdt_init = 0, | |
58 | wdt_change = 1, | |
59 | wdt_cancel = 2, | |
60 | /* flags */ | |
61 | wdt_conceal = 0x80000000, | |
62 | }; | |
63 | ||
64 | static int __diag288(enum vmwdt_func func, unsigned int timeout, | |
65 | char *cmd, size_t len) | |
66 | { | |
94c12cc7 MS |
67 | register unsigned long __func asm("2") = func; |
68 | register unsigned long __timeout asm("3") = timeout; | |
69 | register unsigned long __cmdp asm("4") = virt_to_phys(cmd); | |
70 | register unsigned long __cmdl asm("5") = len; | |
1da177e4 LT |
71 | int err; |
72 | ||
94c12cc7 MS |
73 | err = -EINVAL; |
74 | asm volatile( | |
75 | " diag %1,%3,0x288\n" | |
76 | "0: la %0,0\n" | |
77 | "1:\n" | |
78 | EX_TABLE(0b,1b) | |
2b12f996 HC |
79 | : "+d" (err) : "d"(__func), "d"(__timeout), |
80 | "d"(__cmdp), "d"(__cmdl) : "1", "cc"); | |
1da177e4 LT |
81 | return err; |
82 | } | |
83 | ||
84 | static int vmwdt_keepalive(void) | |
85 | { | |
86 | /* we allocate new memory every time to avoid having | |
87 | * to track the state. static allocation is not an | |
88 | * option since that might not be contiguous in real | |
89 | * storage in case of a modular build */ | |
90 | static char *ebc_cmd; | |
91 | size_t len; | |
92 | int ret; | |
93 | unsigned int func; | |
94 | ||
95 | ebc_cmd = kmalloc(MAX_CMDLEN, GFP_KERNEL); | |
96 | if (!ebc_cmd) | |
97 | return -ENOMEM; | |
98 | ||
99 | len = strlcpy(ebc_cmd, vmwdt_cmd, MAX_CMDLEN); | |
100 | ASCEBC(ebc_cmd, MAX_CMDLEN); | |
101 | EBC_TOUPPER(ebc_cmd, MAX_CMDLEN); | |
102 | ||
103 | func = vmwdt_conceal ? (wdt_init | wdt_conceal) : wdt_init; | |
58872d5f | 104 | set_bit(VMWDT_RUNNING, &vmwdt_is_open); |
1da177e4 | 105 | ret = __diag288(func, vmwdt_interval, ebc_cmd, len); |
0d130066 | 106 | WARN_ON(ret != 0); |
1da177e4 | 107 | kfree(ebc_cmd); |
1da177e4 LT |
108 | return ret; |
109 | } | |
110 | ||
111 | static int vmwdt_disable(void) | |
112 | { | |
113 | int ret = __diag288(wdt_cancel, 0, "", 0); | |
0d130066 | 114 | WARN_ON(ret != 0); |
58872d5f | 115 | clear_bit(VMWDT_RUNNING, &vmwdt_is_open); |
1da177e4 LT |
116 | return ret; |
117 | } | |
118 | ||
119 | static int __init vmwdt_probe(void) | |
120 | { | |
121 | /* there is no real way to see if the watchdog is supported, | |
122 | * so we try initializing it with a NOP command ("BEGIN") | |
123 | * that won't cause any harm even if the following disable | |
124 | * fails for some reason */ | |
125 | static char __initdata ebc_begin[] = { | |
126 | 194, 197, 199, 201, 213 | |
127 | }; | |
0d130066 | 128 | if (__diag288(wdt_init, 15, ebc_begin, sizeof(ebc_begin)) != 0) |
1da177e4 | 129 | return -EINVAL; |
1da177e4 LT |
130 | return vmwdt_disable(); |
131 | } | |
132 | ||
133 | static int vmwdt_open(struct inode *i, struct file *f) | |
134 | { | |
135 | int ret; | |
3e0420f0 | 136 | lock_kernel(); |
58872d5f | 137 | if (test_and_set_bit(VMWDT_OPEN, &vmwdt_is_open)) { |
3e0420f0 | 138 | unlock_kernel(); |
1da177e4 | 139 | return -EBUSY; |
3e0420f0 | 140 | } |
1da177e4 LT |
141 | ret = vmwdt_keepalive(); |
142 | if (ret) | |
58872d5f | 143 | clear_bit(VMWDT_OPEN, &vmwdt_is_open); |
3e0420f0 | 144 | unlock_kernel(); |
1da177e4 LT |
145 | return ret ? ret : nonseekable_open(i, f); |
146 | } | |
147 | ||
148 | static int vmwdt_close(struct inode *i, struct file *f) | |
149 | { | |
150 | if (vmwdt_expect_close == 42) | |
151 | vmwdt_disable(); | |
152 | vmwdt_expect_close = 0; | |
58872d5f | 153 | clear_bit(VMWDT_OPEN, &vmwdt_is_open); |
1da177e4 LT |
154 | return 0; |
155 | } | |
156 | ||
157 | static struct watchdog_info vmwdt_info = { | |
158 | .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE, | |
159 | .firmware_version = 0, | |
160 | .identity = "z/VM Watchdog Timer", | |
161 | }; | |
162 | ||
163 | static int vmwdt_ioctl(struct inode *i, struct file *f, | |
164 | unsigned int cmd, unsigned long arg) | |
165 | { | |
166 | switch (cmd) { | |
167 | case WDIOC_GETSUPPORT: | |
168 | if (copy_to_user((void __user *)arg, &vmwdt_info, | |
169 | sizeof(vmwdt_info))) | |
170 | return -EFAULT; | |
171 | return 0; | |
172 | case WDIOC_GETSTATUS: | |
173 | case WDIOC_GETBOOTSTATUS: | |
d2c993d8 | 174 | return put_user(0, (int __user *)arg); |
1da177e4 LT |
175 | case WDIOC_GETTEMP: |
176 | return -EINVAL; | |
177 | case WDIOC_SETOPTIONS: | |
178 | { | |
179 | int options, ret; | |
180 | if (get_user(options, (int __user *)arg)) | |
181 | return -EFAULT; | |
182 | ret = -EINVAL; | |
183 | if (options & WDIOS_DISABLECARD) { | |
184 | ret = vmwdt_disable(); | |
185 | if (ret) | |
186 | return ret; | |
187 | } | |
188 | if (options & WDIOS_ENABLECARD) { | |
189 | ret = vmwdt_keepalive(); | |
190 | } | |
191 | return ret; | |
192 | } | |
193 | case WDIOC_GETTIMEOUT: | |
194 | return put_user(vmwdt_interval, (int __user *)arg); | |
195 | case WDIOC_SETTIMEOUT: | |
196 | { | |
197 | int interval; | |
198 | if (get_user(interval, (int __user *)arg)) | |
199 | return -EFAULT; | |
200 | if (interval < MIN_INTERVAL) | |
201 | return -EINVAL; | |
202 | vmwdt_interval = interval; | |
203 | } | |
204 | return vmwdt_keepalive(); | |
205 | case WDIOC_KEEPALIVE: | |
206 | return vmwdt_keepalive(); | |
207 | } | |
208 | ||
209 | return -EINVAL; | |
210 | } | |
211 | ||
212 | static ssize_t vmwdt_write(struct file *f, const char __user *buf, | |
213 | size_t count, loff_t *ppos) | |
214 | { | |
215 | if(count) { | |
216 | if (!vmwdt_nowayout) { | |
217 | size_t i; | |
218 | ||
219 | /* note: just in case someone wrote the magic character | |
220 | * five months ago... */ | |
221 | vmwdt_expect_close = 0; | |
222 | ||
223 | for (i = 0; i != count; i++) { | |
224 | char c; | |
225 | if (get_user(c, buf+i)) | |
226 | return -EFAULT; | |
227 | if (c == 'V') | |
228 | vmwdt_expect_close = 42; | |
229 | } | |
230 | } | |
231 | /* someone wrote to us, we should restart timer */ | |
232 | vmwdt_keepalive(); | |
233 | } | |
234 | return count; | |
235 | } | |
236 | ||
58872d5f CB |
237 | static int vmwdt_resume(void) |
238 | { | |
239 | clear_bit(VMWDT_OPEN, &vmwdt_is_open); | |
240 | return NOTIFY_DONE; | |
241 | } | |
242 | ||
243 | /* | |
244 | * It makes no sense to go into suspend while the watchdog is running. | |
245 | * Depending on the memory size, the watchdog might trigger, while we | |
246 | * are still saving the memory. | |
247 | * We reuse the open flag to ensure that suspend and watchdog open are | |
248 | * exclusive operations | |
249 | */ | |
250 | static int vmwdt_suspend(void) | |
251 | { | |
252 | if (test_and_set_bit(VMWDT_OPEN, &vmwdt_is_open)) { | |
2c48c4d6 CB |
253 | pr_err("The system cannot be suspended while the watchdog" |
254 | " is in use\n"); | |
58872d5f CB |
255 | return NOTIFY_BAD; |
256 | } | |
257 | if (test_bit(VMWDT_RUNNING, &vmwdt_is_open)) { | |
258 | clear_bit(VMWDT_OPEN, &vmwdt_is_open); | |
2c48c4d6 CB |
259 | pr_err("The system cannot be suspended while the watchdog" |
260 | " is running\n"); | |
58872d5f CB |
261 | return NOTIFY_BAD; |
262 | } | |
263 | return NOTIFY_DONE; | |
264 | } | |
265 | ||
266 | /* | |
267 | * This function is called for suspend and resume. | |
268 | */ | |
269 | static int vmwdt_power_event(struct notifier_block *this, unsigned long event, | |
270 | void *ptr) | |
271 | { | |
272 | switch (event) { | |
273 | case PM_POST_HIBERNATION: | |
274 | case PM_POST_SUSPEND: | |
275 | return vmwdt_resume(); | |
276 | case PM_HIBERNATION_PREPARE: | |
277 | case PM_SUSPEND_PREPARE: | |
278 | return vmwdt_suspend(); | |
279 | default: | |
280 | return NOTIFY_DONE; | |
281 | } | |
282 | } | |
283 | ||
284 | static struct notifier_block vmwdt_power_notifier = { | |
285 | .notifier_call = vmwdt_power_event, | |
286 | }; | |
287 | ||
d54b1fdb | 288 | static const struct file_operations vmwdt_fops = { |
1da177e4 LT |
289 | .open = &vmwdt_open, |
290 | .release = &vmwdt_close, | |
291 | .ioctl = &vmwdt_ioctl, | |
292 | .write = &vmwdt_write, | |
293 | .owner = THIS_MODULE, | |
294 | }; | |
295 | ||
296 | static struct miscdevice vmwdt_dev = { | |
297 | .minor = WATCHDOG_MINOR, | |
298 | .name = "watchdog", | |
299 | .fops = &vmwdt_fops, | |
300 | }; | |
301 | ||
302 | static int __init vmwdt_init(void) | |
303 | { | |
304 | int ret; | |
305 | ||
306 | ret = vmwdt_probe(); | |
307 | if (ret) | |
308 | return ret; | |
58872d5f CB |
309 | ret = register_pm_notifier(&vmwdt_power_notifier); |
310 | if (ret) | |
311 | return ret; | |
312 | ret = misc_register(&vmwdt_dev); | |
313 | if (ret) { | |
314 | unregister_pm_notifier(&vmwdt_power_notifier); | |
315 | return ret; | |
316 | } | |
317 | return 0; | |
1da177e4 LT |
318 | } |
319 | module_init(vmwdt_init); | |
320 | ||
321 | static void __exit vmwdt_exit(void) | |
322 | { | |
58872d5f CB |
323 | unregister_pm_notifier(&vmwdt_power_notifier); |
324 | misc_deregister(&vmwdt_dev); | |
1da177e4 LT |
325 | } |
326 | module_exit(vmwdt_exit); |