xref: /linux/drivers/watchdog/diag288_wdt.c (revision 04eeb606a8383b306f4bc6991da8231b5f3924b0)
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 <linux/io.h>
33 #include <linux/uaccess.h>
34 
35 #define MAX_CMDLEN 240
36 #define DEFAULT_CMD "SYSTEM RESTART"
37 
38 #define MIN_INTERVAL 15     /* Minimal time supported by diag88 */
39 #define MAX_INTERVAL 3600   /* One hour should be enough - pure estimation */
40 
41 #define WDT_DEFAULT_TIMEOUT 30
42 
43 /* Function codes - init, change, cancel */
44 #define WDT_FUNC_INIT 0
45 #define WDT_FUNC_CHANGE 1
46 #define WDT_FUNC_CANCEL 2
47 #define WDT_FUNC_CONCEAL 0x80000000
48 
49 /* Action codes for LPAR watchdog */
50 #define LPARWDT_RESTART 0
51 
52 static char wdt_cmd[MAX_CMDLEN] = DEFAULT_CMD;
53 static bool conceal_on;
54 static bool nowayout_info = WATCHDOG_NOWAYOUT;
55 
56 MODULE_LICENSE("GPL");
57 MODULE_AUTHOR("Arnd Bergmann <arndb@de.ibm.com>");
58 MODULE_AUTHOR("Philipp Hachtmann <phacht@de.ibm.com>");
59 
60 MODULE_DESCRIPTION("System z diag288  Watchdog Timer");
61 
62 module_param_string(cmd, wdt_cmd, MAX_CMDLEN, 0644);
63 MODULE_PARM_DESC(cmd, "CP command that is run when the watchdog triggers (z/VM only)");
64 
65 module_param_named(conceal, conceal_on, bool, 0644);
66 MODULE_PARM_DESC(conceal, "Enable the CONCEAL CP option while the watchdog is active (z/VM only)");
67 
68 module_param_named(nowayout, nowayout_info, bool, 0444);
69 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default = CONFIG_WATCHDOG_NOWAYOUT)");
70 
71 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
72 MODULE_ALIAS("vmwatchdog");
73 
74 static int __diag288(unsigned int func, unsigned int timeout,
75 		     unsigned long action, unsigned int len)
76 {
77 	register unsigned long __func asm("2") = func;
78 	register unsigned long __timeout asm("3") = timeout;
79 	register unsigned long __action asm("4") = action;
80 	register unsigned long __len asm("5") = len;
81 	int err;
82 
83 	err = -EINVAL;
84 	asm volatile(
85 		"	diag	%1, %3, 0x288\n"
86 		"0:	la	%0, 0\n"
87 		"1:\n"
88 		EX_TABLE(0b, 1b)
89 		: "+d" (err) : "d"(__func), "d"(__timeout),
90 		  "d"(__action), "d"(__len) : "1", "cc");
91 	return err;
92 }
93 
94 static int __diag288_vm(unsigned int  func, unsigned int timeout,
95 			char *cmd, size_t len)
96 {
97 	return __diag288(func, timeout, virt_to_phys(cmd), len);
98 }
99 
100 static int __diag288_lpar(unsigned int func, unsigned int timeout,
101 			  unsigned long action)
102 {
103 	return __diag288(func, timeout, action, 0);
104 }
105 
106 static int wdt_start(struct watchdog_device *dev)
107 {
108 	char *ebc_cmd;
109 	size_t len;
110 	int ret;
111 	unsigned int func;
112 
113 	ret = -ENODEV;
114 
115 	if (MACHINE_IS_VM) {
116 		ebc_cmd = kmalloc(MAX_CMDLEN, GFP_KERNEL);
117 		if (!ebc_cmd)
118 			return -ENOMEM;
119 		len = strlcpy(ebc_cmd, wdt_cmd, MAX_CMDLEN);
120 		ASCEBC(ebc_cmd, MAX_CMDLEN);
121 		EBC_TOUPPER(ebc_cmd, MAX_CMDLEN);
122 
123 		func = conceal_on ? (WDT_FUNC_INIT | WDT_FUNC_CONCEAL)
124 			: WDT_FUNC_INIT;
125 		ret = __diag288_vm(func, dev->timeout, ebc_cmd, len);
126 		WARN_ON(ret != 0);
127 		kfree(ebc_cmd);
128 	}
129 
130 	if (MACHINE_IS_LPAR) {
131 		ret = __diag288_lpar(WDT_FUNC_INIT,
132 				     dev->timeout, LPARWDT_RESTART);
133 	}
134 
135 	if (ret) {
136 		pr_err("The watchdog cannot be activated\n");
137 		return ret;
138 	}
139 	pr_info("The watchdog was activated\n");
140 	return 0;
141 }
142 
143 static int wdt_stop(struct watchdog_device *dev)
144 {
145 	int ret;
146 
147 	ret = __diag288(WDT_FUNC_CANCEL, 0, 0, 0);
148 	pr_info("The watchdog was deactivated\n");
149 	return ret;
150 }
151 
152 static int wdt_ping(struct watchdog_device *dev)
153 {
154 	char *ebc_cmd;
155 	size_t len;
156 	int ret;
157 	unsigned int func;
158 
159 	ret = -ENODEV;
160 
161 	if (MACHINE_IS_VM) {
162 		ebc_cmd = kmalloc(MAX_CMDLEN, GFP_KERNEL);
163 		if (!ebc_cmd)
164 			return -ENOMEM;
165 		len = strlcpy(ebc_cmd, wdt_cmd, MAX_CMDLEN);
166 		ASCEBC(ebc_cmd, MAX_CMDLEN);
167 		EBC_TOUPPER(ebc_cmd, MAX_CMDLEN);
168 
169 		/*
170 		 * It seems to be ok to z/VM to use the init function to
171 		 * retrigger the watchdog. On LPAR WDT_FUNC_CHANGE must
172 		 * be used when the watchdog is running.
173 		 */
174 		func = conceal_on ? (WDT_FUNC_INIT | WDT_FUNC_CONCEAL)
175 			: WDT_FUNC_INIT;
176 
177 		ret = __diag288_vm(func, dev->timeout, ebc_cmd, len);
178 		WARN_ON(ret != 0);
179 		kfree(ebc_cmd);
180 	}
181 
182 	if (MACHINE_IS_LPAR)
183 		ret = __diag288_lpar(WDT_FUNC_CHANGE, dev->timeout, 0);
184 
185 	if (ret)
186 		pr_err("The watchdog timer cannot be started or reset\n");
187 	return ret;
188 }
189 
190 static int wdt_set_timeout(struct watchdog_device * dev, unsigned int new_to)
191 {
192 	dev->timeout = new_to;
193 	return wdt_ping(dev);
194 }
195 
196 static struct watchdog_ops wdt_ops = {
197 	.owner = THIS_MODULE,
198 	.start = wdt_start,
199 	.stop = wdt_stop,
200 	.ping = wdt_ping,
201 	.set_timeout = wdt_set_timeout,
202 };
203 
204 static struct watchdog_info wdt_info = {
205 	.options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
206 	.firmware_version = 0,
207 	.identity = "z Watchdog",
208 };
209 
210 static struct watchdog_device wdt_dev = {
211 	.parent = NULL,
212 	.info = &wdt_info,
213 	.ops = &wdt_ops,
214 	.bootstatus = 0,
215 	.timeout = WDT_DEFAULT_TIMEOUT,
216 	.min_timeout = MIN_INTERVAL,
217 	.max_timeout = MAX_INTERVAL,
218 };
219 
220 /*
221  * It makes no sense to go into suspend while the watchdog is running.
222  * Depending on the memory size, the watchdog might trigger, while we
223  * are still saving the memory.
224  * We reuse the open flag to ensure that suspend and watchdog open are
225  * exclusive operations
226  */
227 static int wdt_suspend(void)
228 {
229 	if (test_and_set_bit(WDOG_DEV_OPEN, &wdt_dev.status)) {
230 		pr_err("Linux cannot be suspended while the watchdog is in use\n");
231 		return notifier_from_errno(-EBUSY);
232 	}
233 	if (test_bit(WDOG_ACTIVE, &wdt_dev.status)) {
234 		clear_bit(WDOG_DEV_OPEN, &wdt_dev.status);
235 		pr_err("Linux cannot be suspended while the watchdog is in use\n");
236 		return notifier_from_errno(-EBUSY);
237 	}
238 	return NOTIFY_DONE;
239 }
240 
241 static int wdt_resume(void)
242 {
243 	clear_bit(WDOG_DEV_OPEN, &wdt_dev.status);
244 	return NOTIFY_DONE;
245 }
246 
247 static int wdt_power_event(struct notifier_block *this, unsigned long event,
248 			   void *ptr)
249 {
250 	switch (event) {
251 	case PM_POST_HIBERNATION:
252 	case PM_POST_SUSPEND:
253 		return wdt_resume();
254 	case PM_HIBERNATION_PREPARE:
255 	case PM_SUSPEND_PREPARE:
256 		return wdt_suspend();
257 	default:
258 		return NOTIFY_DONE;
259 	}
260 }
261 
262 static struct notifier_block wdt_power_notifier = {
263 	.notifier_call = wdt_power_event,
264 };
265 
266 static int __init diag288_init(void)
267 {
268 	int ret;
269 	char ebc_begin[] = {
270 		194, 197, 199, 201, 213
271 	};
272 
273 	watchdog_set_nowayout(&wdt_dev, nowayout_info);
274 
275 	if (MACHINE_IS_VM) {
276 		pr_info("The watchdog device driver detected a z/VM environment\n");
277 		if (__diag288_vm(WDT_FUNC_INIT, 15,
278 				 ebc_begin, sizeof(ebc_begin)) != 0) {
279 			pr_err("The watchdog cannot be initialized\n");
280 			return -EINVAL;
281 		}
282 	} else if (MACHINE_IS_LPAR) {
283 		pr_info("The watchdog device driver detected an LPAR environment\n");
284 		if (__diag288_lpar(WDT_FUNC_INIT, 30, LPARWDT_RESTART)) {
285 			pr_err("The watchdog cannot be initialized\n");
286 			return -EINVAL;
287 		}
288 	} else {
289 		pr_err("Linux runs in an environment that does not support the diag288 watchdog\n");
290 		return -ENODEV;
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 
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