blob: 5473c23fcb521d76f7cc941b71cdf2a57efe1bb5 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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
23static char vmwdt_cmd[MAX_CMDLEN] = "IPL";
24static int vmwdt_conceal;
25
Andrey Panin4bfdf372005-07-27 11:43:58 -070026static int vmwdt_nowayout = WATCHDOG_NOWAYOUT;
Linus Torvalds1da177e2005-04-16 15:20:36 -070027
28MODULE_LICENSE("GPL");
29MODULE_AUTHOR("Arnd Bergmann <arndb@de.ibm.com>");
30MODULE_DESCRIPTION("z/VM Watchdog Timer");
31module_param_string(cmd, vmwdt_cmd, MAX_CMDLEN, 0644);
32MODULE_PARM_DESC(cmd, "CP command that is run when the watchdog triggers");
33module_param_named(conceal, vmwdt_conceal, bool, 0644);
34MODULE_PARM_DESC(conceal, "Enable the CONCEAL CP option while the watchdog "
35 " is active");
36module_param_named(nowayout, vmwdt_nowayout, bool, 0);
37MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started"
38 " (default=CONFIG_WATCHDOG_NOWAYOUT)");
39MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
40
41static unsigned int vmwdt_interval = 60;
42static unsigned long vmwdt_is_open;
43static int vmwdt_expect_close;
44
45enum 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
54static 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 (
69#ifdef __s390x__
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
102static 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
133static 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
143static 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
159static 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
170static 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
179static 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
185static 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
234static 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
259static 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
267static struct miscdevice vmwdt_dev = {
268 .minor = WATCHDOG_MINOR,
269 .name = "watchdog",
270 .fops = &vmwdt_fops,
271};
272
273static 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}
282module_init(vmwdt_init);
283
284static void __exit vmwdt_exit(void)
285{
286 WARN_ON(misc_deregister(&vmwdt_dev) != 0);
287}
288module_exit(vmwdt_exit);