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 | |
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 | |
95 | static int diag288_str(unsigned int func, unsigned int timeout, char *cmd) |
96 | { |
97 | ssize_t len; |
98 | |
99 | len = strscpy(p: cmd_buf, q: 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(address: cmd_buf), len); |
106 | } |
107 | |
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, timeout: dev->timeout, cmd: wdt_cmd); |
117 | WARN_ON(ret != 0); |
118 | } else { |
119 | ret = diag288(WDT_FUNC_INIT, timeout: dev->timeout, LPARWDT_RESTART, len: 0); |
120 | } |
121 | |
122 | if (ret) { |
123 | pr_err("The watchdog cannot be activated\n" ); |
124 | return ret; |
125 | } |
126 | return 0; |
127 | } |
128 | |
129 | static int wdt_stop(struct watchdog_device *dev) |
130 | { |
131 | return diag288(WDT_FUNC_CANCEL, timeout: 0, action: 0, len: 0); |
132 | } |
133 | |
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, timeout: dev->timeout, cmd: wdt_cmd); |
149 | WARN_ON(ret != 0); |
150 | } else { |
151 | ret = diag288(WDT_FUNC_CHANGE, timeout: dev->timeout, action: 0, len: 0); |
152 | } |
153 | |
154 | if (ret) |
155 | pr_err("The watchdog timer cannot be started or reset\n" ); |
156 | return ret; |
157 | } |
158 | |
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 | |
189 | static int __init diag288_init(void) |
190 | { |
191 | int ret; |
192 | |
193 | watchdog_set_nowayout(wdd: &wdt_dev, nowayout: 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, cmd: "BEGIN" ); |
203 | if (ret != 0) { |
204 | pr_err("The watchdog cannot be initialized\n" ); |
205 | kfree(objp: cmd_buf); |
206 | return -EINVAL; |
207 | } |
208 | } else { |
209 | if (diag288(WDT_FUNC_INIT, WDT_DEFAULT_TIMEOUT, |
210 | LPARWDT_RESTART, len: 0)) { |
211 | pr_err("The watchdog cannot be initialized\n" ); |
212 | return -EINVAL; |
213 | } |
214 | } |
215 | |
216 | if (diag288(WDT_FUNC_CANCEL, timeout: 0, action: 0, len: 0)) { |
217 | pr_err("The watchdog cannot be deactivated\n" ); |
218 | return -EINVAL; |
219 | } |
220 | |
221 | return watchdog_register_device(&wdt_dev); |
222 | } |
223 | |
224 | static void __exit diag288_exit(void) |
225 | { |
226 | watchdog_unregister_device(&wdt_dev); |
227 | kfree(objp: cmd_buf); |
228 | } |
229 | |
230 | module_init(diag288_init); |
231 | module_exit(diag288_exit); |
232 | |