Commit | Line | Data |
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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 | { | |
94c12cc7 MS |
57 | register unsigned long __func asm("2") = func; |
58 | register unsigned long __timeout asm("3") = timeout; | |
59 | register unsigned long __cmdp asm("4") = virt_to_phys(cmd); | |
60 | register unsigned long __cmdl asm("5") = len; | |
1da177e4 LT |
61 | int err; |
62 | ||
94c12cc7 MS |
63 | err = -EINVAL; |
64 | asm volatile( | |
65 | " diag %1,%3,0x288\n" | |
66 | "0: la %0,0\n" | |
67 | "1:\n" | |
68 | EX_TABLE(0b,1b) | |
69 | : "=d" (err) : "d"(__func), "d"(__timeout), | |
70 | "d"(__cmdp), "d"(__cmdl), "0" (-EINVAL) : "1", "cc"); | |
1da177e4 LT |
71 | return err; |
72 | } | |
73 | ||
74 | static int vmwdt_keepalive(void) | |
75 | { | |
76 | /* we allocate new memory every time to avoid having | |
77 | * to track the state. static allocation is not an | |
78 | * option since that might not be contiguous in real | |
79 | * storage in case of a modular build */ | |
80 | static char *ebc_cmd; | |
81 | size_t len; | |
82 | int ret; | |
83 | unsigned int func; | |
84 | ||
85 | ebc_cmd = kmalloc(MAX_CMDLEN, GFP_KERNEL); | |
86 | if (!ebc_cmd) | |
87 | return -ENOMEM; | |
88 | ||
89 | len = strlcpy(ebc_cmd, vmwdt_cmd, MAX_CMDLEN); | |
90 | ASCEBC(ebc_cmd, MAX_CMDLEN); | |
91 | EBC_TOUPPER(ebc_cmd, MAX_CMDLEN); | |
92 | ||
93 | func = vmwdt_conceal ? (wdt_init | wdt_conceal) : wdt_init; | |
94 | ret = __diag288(func, vmwdt_interval, ebc_cmd, len); | |
95 | kfree(ebc_cmd); | |
96 | ||
97 | if (ret) { | |
98 | printk(KERN_WARNING "%s: problem setting interval %d, " | |
99 | "cmd %s\n", __FUNCTION__, vmwdt_interval, | |
100 | vmwdt_cmd); | |
101 | } | |
102 | return ret; | |
103 | } | |
104 | ||
105 | static int vmwdt_disable(void) | |
106 | { | |
107 | int ret = __diag288(wdt_cancel, 0, "", 0); | |
108 | if (ret) { | |
109 | printk(KERN_WARNING "%s: problem disabling watchdog\n", | |
110 | __FUNCTION__); | |
111 | } | |
112 | return ret; | |
113 | } | |
114 | ||
115 | static int __init vmwdt_probe(void) | |
116 | { | |
117 | /* there is no real way to see if the watchdog is supported, | |
118 | * so we try initializing it with a NOP command ("BEGIN") | |
119 | * that won't cause any harm even if the following disable | |
120 | * fails for some reason */ | |
121 | static char __initdata ebc_begin[] = { | |
122 | 194, 197, 199, 201, 213 | |
123 | }; | |
124 | if (__diag288(wdt_init, 15, ebc_begin, sizeof(ebc_begin)) != 0) { | |
125 | printk(KERN_INFO "z/VM watchdog not available\n"); | |
126 | return -EINVAL; | |
127 | } | |
128 | return vmwdt_disable(); | |
129 | } | |
130 | ||
131 | static int vmwdt_open(struct inode *i, struct file *f) | |
132 | { | |
133 | int ret; | |
134 | if (test_and_set_bit(0, &vmwdt_is_open)) | |
135 | return -EBUSY; | |
136 | ret = vmwdt_keepalive(); | |
137 | if (ret) | |
138 | clear_bit(0, &vmwdt_is_open); | |
139 | return ret ? ret : nonseekable_open(i, f); | |
140 | } | |
141 | ||
142 | static int vmwdt_close(struct inode *i, struct file *f) | |
143 | { | |
144 | if (vmwdt_expect_close == 42) | |
145 | vmwdt_disable(); | |
146 | vmwdt_expect_close = 0; | |
147 | clear_bit(0, &vmwdt_is_open); | |
148 | return 0; | |
149 | } | |
150 | ||
151 | static struct watchdog_info vmwdt_info = { | |
152 | .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE, | |
153 | .firmware_version = 0, | |
154 | .identity = "z/VM Watchdog Timer", | |
155 | }; | |
156 | ||
157 | static int vmwdt_ioctl(struct inode *i, struct file *f, | |
158 | unsigned int cmd, unsigned long arg) | |
159 | { | |
160 | switch (cmd) { | |
161 | case WDIOC_GETSUPPORT: | |
162 | if (copy_to_user((void __user *)arg, &vmwdt_info, | |
163 | sizeof(vmwdt_info))) | |
164 | return -EFAULT; | |
165 | return 0; | |
166 | case WDIOC_GETSTATUS: | |
167 | case WDIOC_GETBOOTSTATUS: | |
d2c993d8 | 168 | return put_user(0, (int __user *)arg); |
1da177e4 LT |
169 | case WDIOC_GETTEMP: |
170 | return -EINVAL; | |
171 | case WDIOC_SETOPTIONS: | |
172 | { | |
173 | int options, ret; | |
174 | if (get_user(options, (int __user *)arg)) | |
175 | return -EFAULT; | |
176 | ret = -EINVAL; | |
177 | if (options & WDIOS_DISABLECARD) { | |
178 | ret = vmwdt_disable(); | |
179 | if (ret) | |
180 | return ret; | |
181 | } | |
182 | if (options & WDIOS_ENABLECARD) { | |
183 | ret = vmwdt_keepalive(); | |
184 | } | |
185 | return ret; | |
186 | } | |
187 | case WDIOC_GETTIMEOUT: | |
188 | return put_user(vmwdt_interval, (int __user *)arg); | |
189 | case WDIOC_SETTIMEOUT: | |
190 | { | |
191 | int interval; | |
192 | if (get_user(interval, (int __user *)arg)) | |
193 | return -EFAULT; | |
194 | if (interval < MIN_INTERVAL) | |
195 | return -EINVAL; | |
196 | vmwdt_interval = interval; | |
197 | } | |
198 | return vmwdt_keepalive(); | |
199 | case WDIOC_KEEPALIVE: | |
200 | return vmwdt_keepalive(); | |
201 | } | |
202 | ||
203 | return -EINVAL; | |
204 | } | |
205 | ||
206 | static ssize_t vmwdt_write(struct file *f, const char __user *buf, | |
207 | size_t count, loff_t *ppos) | |
208 | { | |
209 | if(count) { | |
210 | if (!vmwdt_nowayout) { | |
211 | size_t i; | |
212 | ||
213 | /* note: just in case someone wrote the magic character | |
214 | * five months ago... */ | |
215 | vmwdt_expect_close = 0; | |
216 | ||
217 | for (i = 0; i != count; i++) { | |
218 | char c; | |
219 | if (get_user(c, buf+i)) | |
220 | return -EFAULT; | |
221 | if (c == 'V') | |
222 | vmwdt_expect_close = 42; | |
223 | } | |
224 | } | |
225 | /* someone wrote to us, we should restart timer */ | |
226 | vmwdt_keepalive(); | |
227 | } | |
228 | return count; | |
229 | } | |
230 | ||
d54b1fdb | 231 | static const struct file_operations vmwdt_fops = { |
1da177e4 LT |
232 | .open = &vmwdt_open, |
233 | .release = &vmwdt_close, | |
234 | .ioctl = &vmwdt_ioctl, | |
235 | .write = &vmwdt_write, | |
236 | .owner = THIS_MODULE, | |
237 | }; | |
238 | ||
239 | static struct miscdevice vmwdt_dev = { | |
240 | .minor = WATCHDOG_MINOR, | |
241 | .name = "watchdog", | |
242 | .fops = &vmwdt_fops, | |
243 | }; | |
244 | ||
245 | static int __init vmwdt_init(void) | |
246 | { | |
247 | int ret; | |
248 | ||
249 | ret = vmwdt_probe(); | |
250 | if (ret) | |
251 | return ret; | |
252 | return misc_register(&vmwdt_dev); | |
253 | } | |
254 | module_init(vmwdt_init); | |
255 | ||
256 | static void __exit vmwdt_exit(void) | |
257 | { | |
258 | WARN_ON(misc_deregister(&vmwdt_dev) != 0); | |
259 | } | |
260 | module_exit(vmwdt_exit); |