2 * Watchdog implementation based on z/VM Watchdog Timer API
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.
9 #include <linux/init.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 #include <linux/smp_lock.h>
18 #include <asm/ebcdic.h>
20 #include <asm/uaccess.h>
22 #define MAX_CMDLEN 240
23 #define MIN_INTERVAL 15
24 static char vmwdt_cmd[MAX_CMDLEN] = "IPL";
25 static int vmwdt_conceal;
27 static int vmwdt_nowayout = WATCHDOG_NOWAYOUT;
29 MODULE_LICENSE("GPL");
30 MODULE_AUTHOR("Arnd Bergmann <arndb@de.ibm.com>");
31 MODULE_DESCRIPTION("z/VM Watchdog Timer");
32 module_param_string(cmd, vmwdt_cmd, MAX_CMDLEN, 0644);
33 MODULE_PARM_DESC(cmd, "CP command that is run when the watchdog triggers");
34 module_param_named(conceal, vmwdt_conceal, bool, 0644);
35 MODULE_PARM_DESC(conceal, "Enable the CONCEAL CP option while the watchdog "
37 module_param_named(nowayout, vmwdt_nowayout, bool, 0);
38 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started"
39 " (default=CONFIG_WATCHDOG_NOWAYOUT)");
40 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
42 static unsigned int vmwdt_interval = 60;
43 static unsigned long vmwdt_is_open;
44 static int vmwdt_expect_close;
52 wdt_conceal = 0x80000000,
55 static int __diag288(enum vmwdt_func func, unsigned int timeout,
56 char *cmd, size_t len)
58 register unsigned long __func asm("2") = func;
59 register unsigned long __timeout asm("3") = timeout;
60 register unsigned long __cmdp asm("4") = virt_to_phys(cmd);
61 register unsigned long __cmdl asm("5") = len;
70 : "+d" (err) : "d"(__func), "d"(__timeout),
71 "d"(__cmdp), "d"(__cmdl) : "1", "cc");
75 static int vmwdt_keepalive(void)
77 /* we allocate new memory every time to avoid having
78 * to track the state. static allocation is not an
79 * option since that might not be contiguous in real
80 * storage in case of a modular build */
86 ebc_cmd = kmalloc(MAX_CMDLEN, GFP_KERNEL);
90 len = strlcpy(ebc_cmd, vmwdt_cmd, MAX_CMDLEN);
91 ASCEBC(ebc_cmd, MAX_CMDLEN);
92 EBC_TOUPPER(ebc_cmd, MAX_CMDLEN);
94 func = vmwdt_conceal ? (wdt_init | wdt_conceal) : wdt_init;
95 ret = __diag288(func, vmwdt_interval, ebc_cmd, len);
99 printk(KERN_WARNING "%s: problem setting interval %d, "
100 "cmd %s\n", __func__, vmwdt_interval,
106 static int vmwdt_disable(void)
108 int ret = __diag288(wdt_cancel, 0, "", 0);
110 printk(KERN_WARNING "%s: problem disabling watchdog\n",
116 static int __init vmwdt_probe(void)
118 /* there is no real way to see if the watchdog is supported,
119 * so we try initializing it with a NOP command ("BEGIN")
120 * that won't cause any harm even if the following disable
121 * fails for some reason */
122 static char __initdata ebc_begin[] = {
123 194, 197, 199, 201, 213
125 if (__diag288(wdt_init, 15, ebc_begin, sizeof(ebc_begin)) != 0) {
126 printk(KERN_INFO "z/VM watchdog not available\n");
129 return vmwdt_disable();
132 static int vmwdt_open(struct inode *i, struct file *f)
136 if (test_and_set_bit(0, &vmwdt_is_open)) {
140 ret = vmwdt_keepalive();
142 clear_bit(0, &vmwdt_is_open);
144 return ret ? ret : nonseekable_open(i, f);
147 static int vmwdt_close(struct inode *i, struct file *f)
149 if (vmwdt_expect_close == 42)
151 vmwdt_expect_close = 0;
152 clear_bit(0, &vmwdt_is_open);
156 static struct watchdog_info vmwdt_info = {
157 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
158 .firmware_version = 0,
159 .identity = "z/VM Watchdog Timer",
162 static int vmwdt_ioctl(struct inode *i, struct file *f,
163 unsigned int cmd, unsigned long arg)
166 case WDIOC_GETSUPPORT:
167 if (copy_to_user((void __user *)arg, &vmwdt_info,
171 case WDIOC_GETSTATUS:
172 case WDIOC_GETBOOTSTATUS:
173 return put_user(0, (int __user *)arg);
176 case WDIOC_SETOPTIONS:
179 if (get_user(options, (int __user *)arg))
182 if (options & WDIOS_DISABLECARD) {
183 ret = vmwdt_disable();
187 if (options & WDIOS_ENABLECARD) {
188 ret = vmwdt_keepalive();
192 case WDIOC_GETTIMEOUT:
193 return put_user(vmwdt_interval, (int __user *)arg);
194 case WDIOC_SETTIMEOUT:
197 if (get_user(interval, (int __user *)arg))
199 if (interval < MIN_INTERVAL)
201 vmwdt_interval = interval;
203 return vmwdt_keepalive();
204 case WDIOC_KEEPALIVE:
205 return vmwdt_keepalive();
211 static ssize_t vmwdt_write(struct file *f, const char __user *buf,
212 size_t count, loff_t *ppos)
215 if (!vmwdt_nowayout) {
218 /* note: just in case someone wrote the magic character
219 * five months ago... */
220 vmwdt_expect_close = 0;
222 for (i = 0; i != count; i++) {
224 if (get_user(c, buf+i))
227 vmwdt_expect_close = 42;
230 /* someone wrote to us, we should restart timer */
236 static const struct file_operations vmwdt_fops = {
238 .release = &vmwdt_close,
239 .ioctl = &vmwdt_ioctl,
240 .write = &vmwdt_write,
241 .owner = THIS_MODULE,
244 static struct miscdevice vmwdt_dev = {
245 .minor = WATCHDOG_MINOR,
250 static int __init vmwdt_init(void)
257 return misc_register(&vmwdt_dev);
259 module_init(vmwdt_init);
261 static void __exit vmwdt_exit(void)
263 WARN_ON(misc_deregister(&vmwdt_dev) != 0);
265 module_exit(vmwdt_exit);