1 /*
2 * Watchdog driver for z/VM and LPAR using the diag 288 interface.
3 *
4 * Under z/VM, expiration of the watchdog will send a "system restart" command
5 * to CP.
6 *
7 * The command can be altered using the module parameter "cmd". This is
8 * not recommended because it's only supported on z/VM but not whith LPAR.
9 *
10 * On LPAR, the watchdog will always trigger a system restart. the module
11 * paramter cmd is meaningless here.
12 *
13 *
14 * Copyright IBM Corp. 2004, 2013
15 * Author(s): Arnd Bergmann (arndb@de.ibm.com)
16 * Philipp Hachtmann (phacht@de.ibm.com)
17 *
18 */
19
20 #define KMSG_COMPONENT "diag288_wdt"
21 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
22
23 #include <linux/init.h>
24 #include <linux/kernel.h>
25 #include <linux/module.h>
26 #include <linux/moduleparam.h>
27 #include <linux/slab.h>
28 #include <linux/miscdevice.h>
29 #include <linux/watchdog.h>
30 #include <linux/suspend.h>
31 #include <asm/ebcdic.h>
32 #include <asm/diag.h>
33 #include <linux/io.h>
34 #include <linux/uaccess.h>
35
36 #define MAX_CMDLEN 240
37 #define DEFAULT_CMD "SYSTEM RESTART"
38
39 #define MIN_INTERVAL 15 /* Minimal time supported by diag88 */
40 #define MAX_INTERVAL 3600 /* One hour should be enough - pure estimation */
41
42 #define WDT_DEFAULT_TIMEOUT 30
43
44 /* Function codes - init, change, cancel */
45 #define WDT_FUNC_INIT 0
46 #define WDT_FUNC_CHANGE 1
47 #define WDT_FUNC_CANCEL 2
48 #define WDT_FUNC_CONCEAL 0x80000000
49
50 /* Action codes for LPAR watchdog */
51 #define LPARWDT_RESTART 0
52
53 static char wdt_cmd[MAX_CMDLEN] = DEFAULT_CMD;
54 static bool conceal_on;
55 static bool nowayout_info = WATCHDOG_NOWAYOUT;
56
57 MODULE_LICENSE("GPL");
58 MODULE_AUTHOR("Arnd Bergmann <arndb@de.ibm.com>");
59 MODULE_AUTHOR("Philipp Hachtmann <phacht@de.ibm.com>");
60
61 MODULE_DESCRIPTION("System z diag288 Watchdog Timer");
62
63 module_param_string(cmd, wdt_cmd, MAX_CMDLEN, 0644);
64 MODULE_PARM_DESC(cmd, "CP command that is run when the watchdog triggers (z/VM only)");
65
66 module_param_named(conceal, conceal_on, bool, 0644);
67 MODULE_PARM_DESC(conceal, "Enable the CONCEAL CP option while the watchdog is active (z/VM only)");
68
69 module_param_named(nowayout, nowayout_info, bool, 0444);
70 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default = CONFIG_WATCHDOG_NOWAYOUT)");
71
72 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
73 MODULE_ALIAS("vmwatchdog");
74
__diag288(unsigned int func,unsigned int timeout,unsigned long action,unsigned int len)75 static int __diag288(unsigned int func, unsigned int timeout,
76 unsigned long action, unsigned int len)
77 {
78 register unsigned long __func asm("2") = func;
79 register unsigned long __timeout asm("3") = timeout;
80 register unsigned long __action asm("4") = action;
81 register unsigned long __len asm("5") = len;
82 int err;
83
84 err = -EINVAL;
85 asm volatile(
86 " diag %1, %3, 0x288\n"
87 "0: la %0, 0\n"
88 "1:\n"
89 EX_TABLE(0b, 1b)
90 : "+d" (err) : "d"(__func), "d"(__timeout),
91 "d"(__action), "d"(__len) : "1", "cc");
92 return err;
93 }
94
__diag288_vm(unsigned int func,unsigned int timeout,char * cmd,size_t len)95 static int __diag288_vm(unsigned int func, unsigned int timeout,
96 char *cmd, size_t len)
97 {
98 diag_stat_inc(DIAG_STAT_X288);
99 return __diag288(func, timeout, virt_to_phys(cmd), len);
100 }
101
__diag288_lpar(unsigned int func,unsigned int timeout,unsigned long action)102 static int __diag288_lpar(unsigned int func, unsigned int timeout,
103 unsigned long action)
104 {
105 diag_stat_inc(DIAG_STAT_X288);
106 return __diag288(func, timeout, action, 0);
107 }
108
109 static unsigned long wdt_status;
110
111 #define DIAG_WDOG_BUSY 0
112
wdt_start(struct watchdog_device * dev)113 static int wdt_start(struct watchdog_device *dev)
114 {
115 char *ebc_cmd;
116 size_t len;
117 int ret;
118 unsigned int func;
119
120 if (test_and_set_bit(DIAG_WDOG_BUSY, &wdt_status))
121 return -EBUSY;
122
123 ret = -ENODEV;
124
125 if (MACHINE_IS_VM) {
126 ebc_cmd = kmalloc(MAX_CMDLEN, GFP_KERNEL);
127 if (!ebc_cmd) {
128 clear_bit(DIAG_WDOG_BUSY, &wdt_status);
129 return -ENOMEM;
130 }
131 len = strlcpy(ebc_cmd, wdt_cmd, MAX_CMDLEN);
132 ASCEBC(ebc_cmd, MAX_CMDLEN);
133 EBC_TOUPPER(ebc_cmd, MAX_CMDLEN);
134
135 func = conceal_on ? (WDT_FUNC_INIT | WDT_FUNC_CONCEAL)
136 : WDT_FUNC_INIT;
137 ret = __diag288_vm(func, dev->timeout, ebc_cmd, len);
138 WARN_ON(ret != 0);
139 kfree(ebc_cmd);
140 } else {
141 ret = __diag288_lpar(WDT_FUNC_INIT,
142 dev->timeout, LPARWDT_RESTART);
143 }
144
145 if (ret) {
146 pr_err("The watchdog cannot be activated\n");
147 clear_bit(DIAG_WDOG_BUSY, &wdt_status);
148 return ret;
149 }
150 return 0;
151 }
152
wdt_stop(struct watchdog_device * dev)153 static int wdt_stop(struct watchdog_device *dev)
154 {
155 int ret;
156
157 diag_stat_inc(DIAG_STAT_X288);
158 ret = __diag288(WDT_FUNC_CANCEL, 0, 0, 0);
159
160 clear_bit(DIAG_WDOG_BUSY, &wdt_status);
161
162 return ret;
163 }
164
wdt_ping(struct watchdog_device * dev)165 static int wdt_ping(struct watchdog_device *dev)
166 {
167 char *ebc_cmd;
168 size_t len;
169 int ret;
170 unsigned int func;
171
172 ret = -ENODEV;
173
174 if (MACHINE_IS_VM) {
175 ebc_cmd = kmalloc(MAX_CMDLEN, GFP_KERNEL);
176 if (!ebc_cmd)
177 return -ENOMEM;
178 len = strlcpy(ebc_cmd, wdt_cmd, MAX_CMDLEN);
179 ASCEBC(ebc_cmd, MAX_CMDLEN);
180 EBC_TOUPPER(ebc_cmd, MAX_CMDLEN);
181
182 /*
183 * It seems to be ok to z/VM to use the init function to
184 * retrigger the watchdog. On LPAR WDT_FUNC_CHANGE must
185 * be used when the watchdog is running.
186 */
187 func = conceal_on ? (WDT_FUNC_INIT | WDT_FUNC_CONCEAL)
188 : WDT_FUNC_INIT;
189
190 ret = __diag288_vm(func, dev->timeout, ebc_cmd, len);
191 WARN_ON(ret != 0);
192 kfree(ebc_cmd);
193 } else {
194 ret = __diag288_lpar(WDT_FUNC_CHANGE, dev->timeout, 0);
195 }
196
197 if (ret)
198 pr_err("The watchdog timer cannot be started or reset\n");
199 return ret;
200 }
201
wdt_set_timeout(struct watchdog_device * dev,unsigned int new_to)202 static int wdt_set_timeout(struct watchdog_device * dev, unsigned int new_to)
203 {
204 dev->timeout = new_to;
205 return wdt_ping(dev);
206 }
207
208 static const struct watchdog_ops wdt_ops = {
209 .owner = THIS_MODULE,
210 .start = wdt_start,
211 .stop = wdt_stop,
212 .ping = wdt_ping,
213 .set_timeout = wdt_set_timeout,
214 };
215
216 static const struct watchdog_info wdt_info = {
217 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
218 .firmware_version = 0,
219 .identity = "z Watchdog",
220 };
221
222 static struct watchdog_device wdt_dev = {
223 .parent = NULL,
224 .info = &wdt_info,
225 .ops = &wdt_ops,
226 .bootstatus = 0,
227 .timeout = WDT_DEFAULT_TIMEOUT,
228 .min_timeout = MIN_INTERVAL,
229 .max_timeout = MAX_INTERVAL,
230 };
231
232 /*
233 * It makes no sense to go into suspend while the watchdog is running.
234 * Depending on the memory size, the watchdog might trigger, while we
235 * are still saving the memory.
236 */
wdt_suspend(void)237 static int wdt_suspend(void)
238 {
239 if (test_and_set_bit(DIAG_WDOG_BUSY, &wdt_status)) {
240 pr_err("Linux cannot be suspended while the watchdog is in use\n");
241 return notifier_from_errno(-EBUSY);
242 }
243 return NOTIFY_DONE;
244 }
245
wdt_resume(void)246 static int wdt_resume(void)
247 {
248 clear_bit(DIAG_WDOG_BUSY, &wdt_status);
249 return NOTIFY_DONE;
250 }
251
wdt_power_event(struct notifier_block * this,unsigned long event,void * ptr)252 static int wdt_power_event(struct notifier_block *this, unsigned long event,
253 void *ptr)
254 {
255 switch (event) {
256 case PM_POST_HIBERNATION:
257 case PM_POST_SUSPEND:
258 return wdt_resume();
259 case PM_HIBERNATION_PREPARE:
260 case PM_SUSPEND_PREPARE:
261 return wdt_suspend();
262 default:
263 return NOTIFY_DONE;
264 }
265 }
266
267 static struct notifier_block wdt_power_notifier = {
268 .notifier_call = wdt_power_event,
269 };
270
diag288_init(void)271 static int __init diag288_init(void)
272 {
273 int ret;
274 char ebc_begin[] = {
275 194, 197, 199, 201, 213
276 };
277
278 watchdog_set_nowayout(&wdt_dev, nowayout_info);
279
280 if (MACHINE_IS_VM) {
281 if (__diag288_vm(WDT_FUNC_INIT, 15,
282 ebc_begin, sizeof(ebc_begin)) != 0) {
283 pr_err("The watchdog cannot be initialized\n");
284 return -EINVAL;
285 }
286 } else {
287 if (__diag288_lpar(WDT_FUNC_INIT, 30, LPARWDT_RESTART)) {
288 pr_err("The watchdog cannot be initialized\n");
289 return -EINVAL;
290 }
291 }
292
293 if (__diag288_lpar(WDT_FUNC_CANCEL, 0, 0)) {
294 pr_err("The watchdog cannot be deactivated\n");
295 return -EINVAL;
296 }
297
298 ret = register_pm_notifier(&wdt_power_notifier);
299 if (ret)
300 return ret;
301
302 ret = watchdog_register_device(&wdt_dev);
303 if (ret)
304 unregister_pm_notifier(&wdt_power_notifier);
305
306 return ret;
307 }
308
diag288_exit(void)309 static void __exit diag288_exit(void)
310 {
311 watchdog_unregister_device(&wdt_dev);
312 unregister_pm_notifier(&wdt_power_notifier);
313 }
314
315 module_init(diag288_init);
316 module_exit(diag288_exit);
317
