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 with LPAR.
10 *
11 * On LPAR, the watchdog will always trigger a system restart. The module
12 * parameter 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 pr_fmt(fmt) "diag288_wdt: " 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/watchdog.h>
29 #include <asm/machine.h>
30 #include <asm/ebcdic.h>
31 #include <asm/diag288.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 static char wdt_cmd[MAX_CMDLEN] = DEFAULT_CMD;
39 static bool conceal_on;
40 static bool nowayout_info = WATCHDOG_NOWAYOUT;
41
42 MODULE_LICENSE("GPL");
43 MODULE_AUTHOR("Arnd Bergmann <arndb@de.ibm.com>");
44 MODULE_AUTHOR("Philipp Hachtmann <phacht@de.ibm.com>");
45
46 MODULE_DESCRIPTION("System z diag288 Watchdog Timer");
47
48 module_param_string(cmd, wdt_cmd, MAX_CMDLEN, 0644);
49 MODULE_PARM_DESC(cmd, "CP command that is run when the watchdog triggers (z/VM only)");
50
51 module_param_named(conceal, conceal_on, bool, 0644);
52 MODULE_PARM_DESC(conceal, "Enable the CONCEAL CP option while the watchdog is active (z/VM only)");
53
54 module_param_named(nowayout, nowayout_info, bool, 0444);
55 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default = CONFIG_WATCHDOG_NOWAYOUT)");
56
57 MODULE_ALIAS("vmwatchdog");
58
59 static char *cmd_buf;
60
diag288(unsigned int func,unsigned int timeout,unsigned long action,unsigned int len)61 static int diag288(unsigned int func, unsigned int timeout,
62 unsigned long action, unsigned int len)
63 {
64 diag_stat_inc(DIAG_STAT_X288);
65 return __diag288(func, timeout, action, len);
66 }
67
diag288_str(unsigned int func,unsigned int timeout,char * cmd)68 static int diag288_str(unsigned int func, unsigned int timeout, char *cmd)
69 {
70 ssize_t len;
71
72 len = strscpy(cmd_buf, cmd, MAX_CMDLEN);
73 if (len < 0)
74 return len;
75 ASCEBC(cmd_buf, MAX_CMDLEN);
76 EBC_TOUPPER(cmd_buf, MAX_CMDLEN);
77
78 return diag288(func, timeout, virt_to_phys(cmd_buf), len);
79 }
80
wdt_start(struct watchdog_device * dev)81 static int wdt_start(struct watchdog_device *dev)
82 {
83 int ret;
84 unsigned int func;
85
86 if (machine_is_vm()) {
87 func = conceal_on ? (WDT_FUNC_INIT | WDT_FUNC_CONCEAL)
88 : WDT_FUNC_INIT;
89 ret = diag288_str(func, dev->timeout, wdt_cmd);
90 WARN_ON(ret != 0);
91 } else {
92 ret = diag288(WDT_FUNC_INIT, dev->timeout, LPARWDT_RESTART, 0);
93 }
94
95 if (ret) {
96 pr_err("The watchdog cannot be activated\n");
97 return ret;
98 }
99 return 0;
100 }
101
wdt_stop(struct watchdog_device * dev)102 static int wdt_stop(struct watchdog_device *dev)
103 {
104 return diag288(WDT_FUNC_CANCEL, 0, 0, 0);
105 }
106
wdt_ping(struct watchdog_device * dev)107 static int wdt_ping(struct watchdog_device *dev)
108 {
109 int ret;
110 unsigned int func;
111
112 if (machine_is_vm()) {
113 /*
114 * It seems to be ok to z/VM to use the init function to
115 * retrigger the watchdog. On LPAR WDT_FUNC_CHANGE must
116 * be used when the watchdog is running.
117 */
118 func = conceal_on ? (WDT_FUNC_INIT | WDT_FUNC_CONCEAL)
119 : WDT_FUNC_INIT;
120
121 ret = diag288_str(func, dev->timeout, wdt_cmd);
122 WARN_ON(ret != 0);
123 } else {
124 ret = diag288(WDT_FUNC_CHANGE, dev->timeout, 0, 0);
125 }
126
127 if (ret)
128 pr_err("The watchdog timer cannot be started or reset\n");
129 return ret;
130 }
131
wdt_set_timeout(struct watchdog_device * dev,unsigned int new_to)132 static int wdt_set_timeout(struct watchdog_device * dev, unsigned int new_to)
133 {
134 dev->timeout = new_to;
135 return wdt_ping(dev);
136 }
137
138 static const struct watchdog_ops wdt_ops = {
139 .owner = THIS_MODULE,
140 .start = wdt_start,
141 .stop = wdt_stop,
142 .ping = wdt_ping,
143 .set_timeout = wdt_set_timeout,
144 };
145
146 static const struct watchdog_info wdt_info = {
147 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
148 .firmware_version = 0,
149 .identity = "z Watchdog",
150 };
151
152 static struct watchdog_device wdt_dev = {
153 .parent = NULL,
154 .info = &wdt_info,
155 .ops = &wdt_ops,
156 .bootstatus = 0,
157 .timeout = WDT_DEFAULT_TIMEOUT,
158 .min_timeout = MIN_INTERVAL,
159 .max_timeout = MAX_INTERVAL,
160 };
161
diag288_init(void)162 static int __init diag288_init(void)
163 {
164 watchdog_set_nowayout(&wdt_dev, nowayout_info);
165
166 if (machine_is_vm()) {
167 cmd_buf = kmalloc(MAX_CMDLEN, GFP_KERNEL);
168 if (!cmd_buf) {
169 pr_err("The watchdog cannot be initialized\n");
170 return -ENOMEM;
171 }
172 }
173
174 return watchdog_register_device(&wdt_dev);
175 }
176
diag288_exit(void)177 static void __exit diag288_exit(void)
178 {
179 watchdog_unregister_device(&wdt_dev);
180 kfree(cmd_buf);
181 }
182
183 module_cpu_feature_match(S390_CPU_FEATURE_D288, diag288_init);
184 module_exit(diag288_exit);
185