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1da177e4 LT |
1 | /* |
2 | * Watchdog implementation based on z/VM Watchdog Timer API | |
3 | * | |
4 | * The user space watchdog daemon can use this driver as | |
5 | * /dev/vmwatchdog to have z/VM execute the specified CP | |
6 | * command when the timeout expires. The default command is | |
7 | * "IPL", which which cause an immediate reboot. | |
8 | */ | |
9 | #include <linux/init.h> | |
10 | #include <linux/fs.h> | |
11 | #include <linux/kernel.h> | |
12 | #include <linux/miscdevice.h> | |
13 | #include <linux/module.h> | |
14 | #include <linux/moduleparam.h> | |
15 | #include <linux/watchdog.h> | |
16 | ||
17 | #include <asm/ebcdic.h> | |
18 | #include <asm/io.h> | |
19 | #include <asm/uaccess.h> | |
20 | ||
21 | #define MAX_CMDLEN 240 | |
22 | #define MIN_INTERVAL 15 | |
23 | static char vmwdt_cmd[MAX_CMDLEN] = "IPL"; | |
24 | static int vmwdt_conceal; | |
25 | ||
4bfdf378 | 26 | static int vmwdt_nowayout = WATCHDOG_NOWAYOUT; |
1da177e4 LT |
27 | |
28 | MODULE_LICENSE("GPL"); | |
29 | MODULE_AUTHOR("Arnd Bergmann <arndb@de.ibm.com>"); | |
30 | MODULE_DESCRIPTION("z/VM Watchdog Timer"); | |
31 | module_param_string(cmd, vmwdt_cmd, MAX_CMDLEN, 0644); | |
32 | MODULE_PARM_DESC(cmd, "CP command that is run when the watchdog triggers"); | |
33 | module_param_named(conceal, vmwdt_conceal, bool, 0644); | |
34 | MODULE_PARM_DESC(conceal, "Enable the CONCEAL CP option while the watchdog " | |
35 | " is active"); | |
36 | module_param_named(nowayout, vmwdt_nowayout, bool, 0); | |
37 | MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started" | |
38 | " (default=CONFIG_WATCHDOG_NOWAYOUT)"); | |
39 | MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); | |
40 | ||
41 | static unsigned int vmwdt_interval = 60; | |
42 | static unsigned long vmwdt_is_open; | |
43 | static int vmwdt_expect_close; | |
44 | ||
45 | enum vmwdt_func { | |
46 | /* function codes */ | |
47 | wdt_init = 0, | |
48 | wdt_change = 1, | |
49 | wdt_cancel = 2, | |
50 | /* flags */ | |
51 | wdt_conceal = 0x80000000, | |
52 | }; | |
53 | ||
54 | static int __diag288(enum vmwdt_func func, unsigned int timeout, | |
55 | char *cmd, size_t len) | |
56 | { | |
57 | register unsigned long __func asm("2"); | |
58 | register unsigned long __timeout asm("3"); | |
59 | register unsigned long __cmdp asm("4"); | |
60 | register unsigned long __cmdl asm("5"); | |
61 | int err; | |
62 | ||
63 | __func = func; | |
64 | __timeout = timeout; | |
65 | __cmdp = virt_to_phys(cmd); | |
66 | __cmdl = len; | |
67 | err = 0; | |
68 | asm volatile ( | |
347a8dc3 | 69 | #ifdef CONFIG_64BIT |
1da177e4 LT |
70 | "diag %2,%4,0x288\n" |
71 | "1: \n" | |
72 | ".section .fixup,\"ax\"\n" | |
73 | "2: lghi %0,%1\n" | |
74 | " jg 1b\n" | |
75 | ".previous\n" | |
76 | ".section __ex_table,\"a\"\n" | |
77 | " .align 8\n" | |
78 | " .quad 1b,2b\n" | |
79 | ".previous\n" | |
80 | #else | |
81 | "diag %2,%4,0x288\n" | |
82 | "1: \n" | |
83 | ".section .fixup,\"ax\"\n" | |
84 | "2: lhi %0,%1\n" | |
85 | " bras 1,3f\n" | |
86 | " .long 1b\n" | |
87 | "3: l 1,0(1)\n" | |
88 | " br 1\n" | |
89 | ".previous\n" | |
90 | ".section __ex_table,\"a\"\n" | |
91 | " .align 4\n" | |
92 | " .long 1b,2b\n" | |
93 | ".previous\n" | |
94 | #endif | |
95 | : "+&d"(err) | |
96 | : "i"(-EINVAL), "d"(__func), "d"(__timeout), | |
97 | "d"(__cmdp), "d"(__cmdl) | |
98 | : "1", "cc"); | |
99 | return err; | |
100 | } | |
101 | ||
102 | static int vmwdt_keepalive(void) | |
103 | { | |
104 | /* we allocate new memory every time to avoid having | |
105 | * to track the state. static allocation is not an | |
106 | * option since that might not be contiguous in real | |
107 | * storage in case of a modular build */ | |
108 | static char *ebc_cmd; | |
109 | size_t len; | |
110 | int ret; | |
111 | unsigned int func; | |
112 | ||
113 | ebc_cmd = kmalloc(MAX_CMDLEN, GFP_KERNEL); | |
114 | if (!ebc_cmd) | |
115 | return -ENOMEM; | |
116 | ||
117 | len = strlcpy(ebc_cmd, vmwdt_cmd, MAX_CMDLEN); | |
118 | ASCEBC(ebc_cmd, MAX_CMDLEN); | |
119 | EBC_TOUPPER(ebc_cmd, MAX_CMDLEN); | |
120 | ||
121 | func = vmwdt_conceal ? (wdt_init | wdt_conceal) : wdt_init; | |
122 | ret = __diag288(func, vmwdt_interval, ebc_cmd, len); | |
123 | kfree(ebc_cmd); | |
124 | ||
125 | if (ret) { | |
126 | printk(KERN_WARNING "%s: problem setting interval %d, " | |
127 | "cmd %s\n", __FUNCTION__, vmwdt_interval, | |
128 | vmwdt_cmd); | |
129 | } | |
130 | return ret; | |
131 | } | |
132 | ||
133 | static int vmwdt_disable(void) | |
134 | { | |
135 | int ret = __diag288(wdt_cancel, 0, "", 0); | |
136 | if (ret) { | |
137 | printk(KERN_WARNING "%s: problem disabling watchdog\n", | |
138 | __FUNCTION__); | |
139 | } | |
140 | return ret; | |
141 | } | |
142 | ||
143 | static int __init vmwdt_probe(void) | |
144 | { | |
145 | /* there is no real way to see if the watchdog is supported, | |
146 | * so we try initializing it with a NOP command ("BEGIN") | |
147 | * that won't cause any harm even if the following disable | |
148 | * fails for some reason */ | |
149 | static char __initdata ebc_begin[] = { | |
150 | 194, 197, 199, 201, 213 | |
151 | }; | |
152 | if (__diag288(wdt_init, 15, ebc_begin, sizeof(ebc_begin)) != 0) { | |
153 | printk(KERN_INFO "z/VM watchdog not available\n"); | |
154 | return -EINVAL; | |
155 | } | |
156 | return vmwdt_disable(); | |
157 | } | |
158 | ||
159 | static int vmwdt_open(struct inode *i, struct file *f) | |
160 | { | |
161 | int ret; | |
162 | if (test_and_set_bit(0, &vmwdt_is_open)) | |
163 | return -EBUSY; | |
164 | ret = vmwdt_keepalive(); | |
165 | if (ret) | |
166 | clear_bit(0, &vmwdt_is_open); | |
167 | return ret ? ret : nonseekable_open(i, f); | |
168 | } | |
169 | ||
170 | static int vmwdt_close(struct inode *i, struct file *f) | |
171 | { | |
172 | if (vmwdt_expect_close == 42) | |
173 | vmwdt_disable(); | |
174 | vmwdt_expect_close = 0; | |
175 | clear_bit(0, &vmwdt_is_open); | |
176 | return 0; | |
177 | } | |
178 | ||
179 | static struct watchdog_info vmwdt_info = { | |
180 | .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE, | |
181 | .firmware_version = 0, | |
182 | .identity = "z/VM Watchdog Timer", | |
183 | }; | |
184 | ||
185 | static int vmwdt_ioctl(struct inode *i, struct file *f, | |
186 | unsigned int cmd, unsigned long arg) | |
187 | { | |
188 | switch (cmd) { | |
189 | case WDIOC_GETSUPPORT: | |
190 | if (copy_to_user((void __user *)arg, &vmwdt_info, | |
191 | sizeof(vmwdt_info))) | |
192 | return -EFAULT; | |
193 | return 0; | |
194 | case WDIOC_GETSTATUS: | |
195 | case WDIOC_GETBOOTSTATUS: | |
196 | return put_user(0, (int *)arg); | |
197 | case WDIOC_GETTEMP: | |
198 | return -EINVAL; | |
199 | case WDIOC_SETOPTIONS: | |
200 | { | |
201 | int options, ret; | |
202 | if (get_user(options, (int __user *)arg)) | |
203 | return -EFAULT; | |
204 | ret = -EINVAL; | |
205 | if (options & WDIOS_DISABLECARD) { | |
206 | ret = vmwdt_disable(); | |
207 | if (ret) | |
208 | return ret; | |
209 | } | |
210 | if (options & WDIOS_ENABLECARD) { | |
211 | ret = vmwdt_keepalive(); | |
212 | } | |
213 | return ret; | |
214 | } | |
215 | case WDIOC_GETTIMEOUT: | |
216 | return put_user(vmwdt_interval, (int __user *)arg); | |
217 | case WDIOC_SETTIMEOUT: | |
218 | { | |
219 | int interval; | |
220 | if (get_user(interval, (int __user *)arg)) | |
221 | return -EFAULT; | |
222 | if (interval < MIN_INTERVAL) | |
223 | return -EINVAL; | |
224 | vmwdt_interval = interval; | |
225 | } | |
226 | return vmwdt_keepalive(); | |
227 | case WDIOC_KEEPALIVE: | |
228 | return vmwdt_keepalive(); | |
229 | } | |
230 | ||
231 | return -EINVAL; | |
232 | } | |
233 | ||
234 | static ssize_t vmwdt_write(struct file *f, const char __user *buf, | |
235 | size_t count, loff_t *ppos) | |
236 | { | |
237 | if(count) { | |
238 | if (!vmwdt_nowayout) { | |
239 | size_t i; | |
240 | ||
241 | /* note: just in case someone wrote the magic character | |
242 | * five months ago... */ | |
243 | vmwdt_expect_close = 0; | |
244 | ||
245 | for (i = 0; i != count; i++) { | |
246 | char c; | |
247 | if (get_user(c, buf+i)) | |
248 | return -EFAULT; | |
249 | if (c == 'V') | |
250 | vmwdt_expect_close = 42; | |
251 | } | |
252 | } | |
253 | /* someone wrote to us, we should restart timer */ | |
254 | vmwdt_keepalive(); | |
255 | } | |
256 | return count; | |
257 | } | |
258 | ||
259 | static struct file_operations vmwdt_fops = { | |
260 | .open = &vmwdt_open, | |
261 | .release = &vmwdt_close, | |
262 | .ioctl = &vmwdt_ioctl, | |
263 | .write = &vmwdt_write, | |
264 | .owner = THIS_MODULE, | |
265 | }; | |
266 | ||
267 | static struct miscdevice vmwdt_dev = { | |
268 | .minor = WATCHDOG_MINOR, | |
269 | .name = "watchdog", | |
270 | .fops = &vmwdt_fops, | |
271 | }; | |
272 | ||
273 | static int __init vmwdt_init(void) | |
274 | { | |
275 | int ret; | |
276 | ||
277 | ret = vmwdt_probe(); | |
278 | if (ret) | |
279 | return ret; | |
280 | return misc_register(&vmwdt_dev); | |
281 | } | |
282 | module_init(vmwdt_init); | |
283 | ||
284 | static void __exit vmwdt_exit(void) | |
285 | { | |
286 | WARN_ON(misc_deregister(&vmwdt_dev) != 0); | |
287 | } | |
288 | module_exit(vmwdt_exit); |