tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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
23static char vmwdt_cmd[MAX_CMDLEN] = "IPL";
24static int vmwdt_conceal;
25
26static int vmwdt_nowayout = WATCHDOG_NOWAYOUT;
27
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") = 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;
61 int err;
62
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) : "1", "cc");
71 return err;
72}
73
74static 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
105static 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
115static 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
131static 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
142static 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
151static 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
157static 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:
168 return put_user(0, (int __user *)arg);
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
206static 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
231static const struct file_operations vmwdt_fops = {
232 .open = &vmwdt_open,
233 .release = &vmwdt_close,
234 .ioctl = &vmwdt_ioctl,
235 .write = &vmwdt_write,
236 .owner = THIS_MODULE,
237};
238
239static struct miscdevice vmwdt_dev = {
240 .minor = WATCHDOG_MINOR,
241 .name = "watchdog",
242 .fops = &vmwdt_fops,
243};
244
245static 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}
254module_init(vmwdt_init);
255
256static void __exit vmwdt_exit(void)
257{
258 WARN_ON(misc_deregister(&vmwdt_dev) != 0);
259}
260module_exit(vmwdt_exit);