1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Watchdog driver for z/VM and LPAR using the diag 288 interface.
4 *
5 * Under z/VM, expiration of the watchdog will send a "system restart" command
6 * to CP.
7 *
8 * The command can be altered using the module parameter "cmd". This is
9 * not recommended because it's only supported on z/VM but not whith LPAR.
10 *
11 * On LPAR, the watchdog will always trigger a system restart. the module
12 * paramter cmd is meaningless here.
13 *
14 *
15 * Copyright IBM Corp. 2004, 2013
16 * Author(s): Arnd Bergmann (arndb@de.ibm.com)
17 *	      Philipp Hachtmann (phacht@de.ibm.com)
18 *
19 */
20
21#define KMSG_COMPONENT "diag288_wdt"
22#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
23
24#include <linux/init.h>
25#include <linux/kernel.h>
26#include <linux/module.h>
27#include <linux/moduleparam.h>
28#include <linux/slab.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
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
52static char wdt_cmd[MAX_CMDLEN] = DEFAULT_CMD;
53static bool conceal_on;
54static bool nowayout_info = WATCHDOG_NOWAYOUT;
55
56MODULE_LICENSE("GPL");
57MODULE_AUTHOR("Arnd Bergmann <arndb@de.ibm.com>");
58MODULE_AUTHOR("Philipp Hachtmann <phacht@de.ibm.com>");
59
60MODULE_DESCRIPTION("System z diag288  Watchdog Timer");
61
62module_param_string(cmd, wdt_cmd, MAX_CMDLEN, 0644);
63MODULE_PARM_DESC(cmd, "CP command that is run when the watchdog triggers (z/VM only)");
64
65module_param_named(conceal, conceal_on, bool, 0644);
66MODULE_PARM_DESC(conceal, "Enable the CONCEAL CP option while the watchdog is active (z/VM only)");
67
68module_param_named(nowayout, nowayout_info, bool, 0444);
69MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default = CONFIG_WATCHDOG_NOWAYOUT)");
70
71MODULE_ALIAS("vmwatchdog");
72
73static int __diag288(unsigned int func, unsigned int timeout,
74		     unsigned long action, unsigned int len)
75{
76	register unsigned long __func asm("2") = func;
77	register unsigned long __timeout asm("3") = timeout;
78	register unsigned long __action asm("4") = action;
79	register unsigned long __len asm("5") = len;
80	int err;
81
82	err = -EINVAL;
83	asm volatile(
84		"	diag	%1, %3, 0x288\n"
85		"0:	la	%0, 0\n"
86		"1:\n"
87		EX_TABLE(0b, 1b)
88		: "+d" (err) : "d"(__func), "d"(__timeout),
89		  "d"(__action), "d"(__len) : "1", "cc", "memory");
90	return err;
91}
92
93static int __diag288_vm(unsigned int  func, unsigned int timeout,
94			char *cmd, size_t len)
95{
96	diag_stat_inc(DIAG_STAT_X288);
97	return __diag288(func, timeout, virt_to_phys(cmd), len);
98}
99
100static int __diag288_lpar(unsigned int func, unsigned int timeout,
101			  unsigned long action)
102{
103	diag_stat_inc(DIAG_STAT_X288);
104	return __diag288(func, timeout, action, 0);
105}
106
107static unsigned long wdt_status;
108
109#define DIAG_WDOG_BUSY	0
110
111static int wdt_start(struct watchdog_device *dev)
112{
113	char *ebc_cmd;
114	size_t len;
115	int ret;
116	unsigned int func;
117
118	if (test_and_set_bit(DIAG_WDOG_BUSY, &wdt_status))
119		return -EBUSY;
120
121	ret = -ENODEV;
122
123	if (MACHINE_IS_VM) {
124		ebc_cmd = kmalloc(MAX_CMDLEN, GFP_KERNEL);
125		if (!ebc_cmd) {
126			clear_bit(DIAG_WDOG_BUSY, &wdt_status);
127			return -ENOMEM;
128		}
129		len = strlcpy(ebc_cmd, wdt_cmd, MAX_CMDLEN);
130		ASCEBC(ebc_cmd, MAX_CMDLEN);
131		EBC_TOUPPER(ebc_cmd, MAX_CMDLEN);
132
133		func = conceal_on ? (WDT_FUNC_INIT | WDT_FUNC_CONCEAL)
134			: WDT_FUNC_INIT;
135		ret = __diag288_vm(func, dev->timeout, ebc_cmd, len);
136		WARN_ON(ret != 0);
137		kfree(ebc_cmd);
138	} else {
139		ret = __diag288_lpar(WDT_FUNC_INIT,
140				     dev->timeout, LPARWDT_RESTART);
141	}
142
143	if (ret) {
144		pr_err("The watchdog cannot be activated\n");
145		clear_bit(DIAG_WDOG_BUSY, &wdt_status);
146		return ret;
147	}
148	return 0;
149}
150
151static int wdt_stop(struct watchdog_device *dev)
152{
153	int ret;
154
155	diag_stat_inc(DIAG_STAT_X288);
156	ret = __diag288(WDT_FUNC_CANCEL, 0, 0, 0);
157
158	clear_bit(DIAG_WDOG_BUSY, &wdt_status);
159
160	return ret;
161}
162
163static int wdt_ping(struct watchdog_device *dev)
164{
165	char *ebc_cmd;
166	size_t len;
167	int ret;
168	unsigned int func;
169
170	ret = -ENODEV;
171
172	if (MACHINE_IS_VM) {
173		ebc_cmd = kmalloc(MAX_CMDLEN, GFP_KERNEL);
174		if (!ebc_cmd)
175			return -ENOMEM;
176		len = strlcpy(ebc_cmd, wdt_cmd, MAX_CMDLEN);
177		ASCEBC(ebc_cmd, MAX_CMDLEN);
178		EBC_TOUPPER(ebc_cmd, MAX_CMDLEN);
179
180		/*
181		 * It seems to be ok to z/VM to use the init function to
182		 * retrigger the watchdog. On LPAR WDT_FUNC_CHANGE must
183		 * be used when the watchdog is running.
184		 */
185		func = conceal_on ? (WDT_FUNC_INIT | WDT_FUNC_CONCEAL)
186			: WDT_FUNC_INIT;
187
188		ret = __diag288_vm(func, dev->timeout, ebc_cmd, len);
189		WARN_ON(ret != 0);
190		kfree(ebc_cmd);
191	} else {
192		ret = __diag288_lpar(WDT_FUNC_CHANGE, dev->timeout, 0);
193	}
194
195	if (ret)
196		pr_err("The watchdog timer cannot be started or reset\n");
197	return ret;
198}
199
200static int wdt_set_timeout(struct watchdog_device * dev, unsigned int new_to)
201{
202	dev->timeout = new_to;
203	return wdt_ping(dev);
204}
205
206static const struct watchdog_ops wdt_ops = {
207	.owner = THIS_MODULE,
208	.start = wdt_start,
209	.stop = wdt_stop,
210	.ping = wdt_ping,
211	.set_timeout = wdt_set_timeout,
212};
213
214static const struct watchdog_info wdt_info = {
215	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
216	.firmware_version = 0,
217	.identity = "z Watchdog",
218};
219
220static struct watchdog_device wdt_dev = {
221	.parent = NULL,
222	.info = &wdt_info,
223	.ops = &wdt_ops,
224	.bootstatus = 0,
225	.timeout = WDT_DEFAULT_TIMEOUT,
226	.min_timeout = MIN_INTERVAL,
227	.max_timeout = MAX_INTERVAL,
228};
229
230/*
231 * It makes no sense to go into suspend while the watchdog is running.
232 * Depending on the memory size, the watchdog might trigger, while we
233 * are still saving the memory.
234 */
235static int wdt_suspend(void)
236{
237	if (test_and_set_bit(DIAG_WDOG_BUSY, &wdt_status)) {
238		pr_err("Linux cannot be suspended while the watchdog is in use\n");
239		return notifier_from_errno(-EBUSY);
240	}
241	return NOTIFY_DONE;
242}
243
244static int wdt_resume(void)
245{
246	clear_bit(DIAG_WDOG_BUSY, &wdt_status);
247	return NOTIFY_DONE;
248}
249
250static int wdt_power_event(struct notifier_block *this, unsigned long event,
251			   void *ptr)
252{
253	switch (event) {
254	case PM_POST_HIBERNATION:
255	case PM_POST_SUSPEND:
256		return wdt_resume();
257	case PM_HIBERNATION_PREPARE:
258	case PM_SUSPEND_PREPARE:
259		return wdt_suspend();
260	default:
261		return NOTIFY_DONE;
262	}
263}
264
265static struct notifier_block wdt_power_notifier = {
266	.notifier_call = wdt_power_event,
267};
268
269static int __init diag288_init(void)
270{
271	int ret;
272	char ebc_begin[] = {
273		194, 197, 199, 201, 213
274	};
275	char *ebc_cmd;
276
277	watchdog_set_nowayout(&wdt_dev, nowayout_info);
278
279	if (MACHINE_IS_VM) {
280		ebc_cmd = kmalloc(sizeof(ebc_begin), GFP_KERNEL);
281		if (!ebc_cmd) {
282			pr_err("The watchdog cannot be initialized\n");
283			return -ENOMEM;
284		}
285		memcpy(ebc_cmd, ebc_begin, sizeof(ebc_begin));
286		ret = __diag288_vm(WDT_FUNC_INIT, 15,
287				   ebc_cmd, sizeof(ebc_begin));
288		kfree(ebc_cmd);
289		if (ret != 0) {
290			pr_err("The watchdog cannot be initialized\n");
291			return -EINVAL;
292		}
293	} else {
294		if (__diag288_lpar(WDT_FUNC_INIT, 30, LPARWDT_RESTART)) {
295			pr_err("The watchdog cannot be initialized\n");
296			return -EINVAL;
297		}
298	}
299
300	if (__diag288_lpar(WDT_FUNC_CANCEL, 0, 0)) {
301		pr_err("The watchdog cannot be deactivated\n");
302		return -EINVAL;
303	}
304
305	ret = register_pm_notifier(&wdt_power_notifier);
306	if (ret)
307		return ret;
308
309	ret = watchdog_register_device(&wdt_dev);
310	if (ret)
311		unregister_pm_notifier(&wdt_power_notifier);
312
313	return ret;
314}
315
316static void __exit diag288_exit(void)
317{
318	watchdog_unregister_device(&wdt_dev);
319	unregister_pm_notifier(&wdt_power_notifier);
320}
321
322module_init(diag288_init);
323module_exit(diag288_exit);
324