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 <asm/ebcdic.h>
31 #include <asm/diag.h>
32 #include <linux/io.h>
33
34 #define MAX_CMDLEN 240
35 #define DEFAULT_CMD "SYSTEM RESTART"
36
37 #define MIN_INTERVAL 15 /* Minimal time supported by diag88 */
38 #define MAX_INTERVAL 3600 /* One hour should be enough - pure estimation */
39
40 #define WDT_DEFAULT_TIMEOUT 30
41
42 /* Function codes - init, change, cancel */
43 #define WDT_FUNC_INIT 0
44 #define WDT_FUNC_CHANGE 1
45 #define WDT_FUNC_CANCEL 2
46 #define WDT_FUNC_CONCEAL 0x80000000
47
48 /* Action codes for LPAR watchdog */
49 #define LPARWDT_RESTART 0
50
51 static char wdt_cmd[MAX_CMDLEN] = DEFAULT_CMD;
52 static bool conceal_on;
53 static bool nowayout_info = WATCHDOG_NOWAYOUT;
54
55 MODULE_LICENSE("GPL");
56 MODULE_AUTHOR("Arnd Bergmann <arndb@de.ibm.com>");
57 MODULE_AUTHOR("Philipp Hachtmann <phacht@de.ibm.com>");
58
59 MODULE_DESCRIPTION("System z diag288 Watchdog Timer");
60
61 module_param_string(cmd, wdt_cmd, MAX_CMDLEN, 0644);
62 MODULE_PARM_DESC(cmd, "CP command that is run when the watchdog triggers (z/VM only)");
63
64 module_param_named(conceal, conceal_on, bool, 0644);
65 MODULE_PARM_DESC(conceal, "Enable the CONCEAL CP option while the watchdog is active (z/VM only)");
66
67 module_param_named(nowayout, nowayout_info, bool, 0444);
68 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default = CONFIG_WATCHDOG_NOWAYOUT)");
69
70 MODULE_ALIAS("vmwatchdog");
71
72 static char *cmd_buf;
73
diag288(unsigned int func,unsigned int timeout,unsigned long action,unsigned int len)74 static int diag288(unsigned int func, unsigned int timeout,
75 unsigned long action, unsigned int len)
76 {
77 union register_pair r1 = { .even = func, .odd = timeout, };
78 union register_pair r3 = { .even = action, .odd = len, };
79 int err;
80
81 diag_stat_inc(DIAG_STAT_X288);
82
83 err = -EINVAL;
84 asm volatile(
85 " diag %[r1],%[r3],0x288\n"
86 "0: la %[err],0\n"
87 "1:\n"
88 EX_TABLE(0b, 1b)
89 : [err] "+d" (err)
90 : [r1] "d" (r1.pair), [r3] "d" (r3.pair)
91 : "cc", "memory");
92 return err;
93 }
94
diag288_str(unsigned int func,unsigned int timeout,char * cmd)95 static int diag288_str(unsigned int func, unsigned int timeout, char *cmd)
96 {
97 ssize_t len;
98
99 len = strscpy(cmd_buf, cmd, MAX_CMDLEN);
100 if (len < 0)
101 return len;
102 ASCEBC(cmd_buf, MAX_CMDLEN);
103 EBC_TOUPPER(cmd_buf, MAX_CMDLEN);
104
105 return diag288(func, timeout, virt_to_phys(cmd_buf), len);
106 }
107
wdt_start(struct watchdog_device * dev)108 static int wdt_start(struct watchdog_device *dev)
109 {
110 int ret;
111 unsigned int func;
112
113 if (MACHINE_IS_VM) {
114 func = conceal_on ? (WDT_FUNC_INIT | WDT_FUNC_CONCEAL)
115 : WDT_FUNC_INIT;
116 ret = diag288_str(func, dev->timeout, wdt_cmd);
117 WARN_ON(ret != 0);
118 } else {
119 ret = diag288(WDT_FUNC_INIT, dev->timeout, LPARWDT_RESTART, 0);
120 }
121
122 if (ret) {
123 pr_err("The watchdog cannot be activated\n");
124 return ret;
125 }
126 return 0;
127 }
128
wdt_stop(struct watchdog_device * dev)129 static int wdt_stop(struct watchdog_device *dev)
130 {
131 return diag288(WDT_FUNC_CANCEL, 0, 0, 0);
132 }
133
wdt_ping(struct watchdog_device * dev)134 static int wdt_ping(struct watchdog_device *dev)
135 {
136 int ret;
137 unsigned int func;
138
139 if (MACHINE_IS_VM) {
140 /*
141 * It seems to be ok to z/VM to use the init function to
142 * retrigger the watchdog. On LPAR WDT_FUNC_CHANGE must
143 * be used when the watchdog is running.
144 */
145 func = conceal_on ? (WDT_FUNC_INIT | WDT_FUNC_CONCEAL)
146 : WDT_FUNC_INIT;
147
148 ret = diag288_str(func, dev->timeout, wdt_cmd);
149 WARN_ON(ret != 0);
150 } else {
151 ret = diag288(WDT_FUNC_CHANGE, dev->timeout, 0, 0);
152 }
153
154 if (ret)
155 pr_err("The watchdog timer cannot be started or reset\n");
156 return ret;
157 }
158
wdt_set_timeout(struct watchdog_device * dev,unsigned int new_to)159 static int wdt_set_timeout(struct watchdog_device * dev, unsigned int new_to)
160 {
161 dev->timeout = new_to;
162 return wdt_ping(dev);
163 }
164
165 static const struct watchdog_ops wdt_ops = {
166 .owner = THIS_MODULE,
167 .start = wdt_start,
168 .stop = wdt_stop,
169 .ping = wdt_ping,
170 .set_timeout = wdt_set_timeout,
171 };
172
173 static const struct watchdog_info wdt_info = {
174 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
175 .firmware_version = 0,
176 .identity = "z Watchdog",
177 };
178
179 static struct watchdog_device wdt_dev = {
180 .parent = NULL,
181 .info = &wdt_info,
182 .ops = &wdt_ops,
183 .bootstatus = 0,
184 .timeout = WDT_DEFAULT_TIMEOUT,
185 .min_timeout = MIN_INTERVAL,
186 .max_timeout = MAX_INTERVAL,
187 };
188
diag288_init(void)189 static int __init diag288_init(void)
190 {
191 int ret;
192
193 watchdog_set_nowayout(&wdt_dev, nowayout_info);
194
195 if (MACHINE_IS_VM) {
196 cmd_buf = kmalloc(MAX_CMDLEN, GFP_KERNEL);
197 if (!cmd_buf) {
198 pr_err("The watchdog cannot be initialized\n");
199 return -ENOMEM;
200 }
201
202 ret = diag288_str(WDT_FUNC_INIT, MIN_INTERVAL, "BEGIN");
203 if (ret != 0) {
204 pr_err("The watchdog cannot be initialized\n");
205 kfree(cmd_buf);
206 return -EINVAL;
207 }
208 } else {
209 if (diag288(WDT_FUNC_INIT, WDT_DEFAULT_TIMEOUT,
210 LPARWDT_RESTART, 0)) {
211 pr_err("The watchdog cannot be initialized\n");
212 return -EINVAL;
213 }
214 }
215
216 if (diag288(WDT_FUNC_CANCEL, 0, 0, 0)) {
217 pr_err("The watchdog cannot be deactivated\n");
218 return -EINVAL;
219 }
220
221 return watchdog_register_device(&wdt_dev);
222 }
223
diag288_exit(void)224 static void __exit diag288_exit(void)
225 {
226 watchdog_unregister_device(&wdt_dev);
227 kfree(cmd_buf);
228 }
229
230 module_init(diag288_init);
231 module_exit(diag288_exit);
232