1 /*
2 * sun4v watchdog timer
3 * (c) Copyright 2016 Oracle Corporation
4 *
5 * Implement a simple watchdog driver using the built-in sun4v hypervisor
6 * watchdog support. If time expires, the hypervisor stops or bounces
7 * the guest domain.
8 *
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License
11 * as published by the Free Software Foundation; either version
12 * 2 of the License, or (at your option) any later version.
13 */
14
15 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
16
17 #include <linux/errno.h>
18 #include <linux/init.h>
19 #include <linux/kernel.h>
20 #include <linux/module.h>
21 #include <linux/moduleparam.h>
22 #include <linux/watchdog.h>
23 #include <asm/hypervisor.h>
24 #include <asm/mdesc.h>
25
26 #define WDT_TIMEOUT 60
27 #define WDT_MAX_TIMEOUT 31536000
28 #define WDT_MIN_TIMEOUT 1
29 #define WDT_DEFAULT_RESOLUTION_MS 1000 /* 1 second */
30
31 static unsigned int timeout;
32 module_param(timeout, uint, 0);
33 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
34 __MODULE_STRING(WDT_TIMEOUT) ")");
35
36 static bool nowayout = WATCHDOG_NOWAYOUT;
37 module_param(nowayout, bool, S_IRUGO);
38 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
39 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
40
sun4v_wdt_stop(struct watchdog_device * wdd)41 static int sun4v_wdt_stop(struct watchdog_device *wdd)
42 {
43 sun4v_mach_set_watchdog(0, NULL);
44
45 return 0;
46 }
47
sun4v_wdt_ping(struct watchdog_device * wdd)48 static int sun4v_wdt_ping(struct watchdog_device *wdd)
49 {
50 int hverr;
51
52 /*
53 * HV watchdog timer will round up the timeout
54 * passed in to the nearest multiple of the
55 * watchdog resolution in milliseconds.
56 */
57 hverr = sun4v_mach_set_watchdog(wdd->timeout * 1000, NULL);
58 if (hverr == HV_EINVAL)
59 return -EINVAL;
60
61 return 0;
62 }
63
sun4v_wdt_set_timeout(struct watchdog_device * wdd,unsigned int timeout)64 static int sun4v_wdt_set_timeout(struct watchdog_device *wdd,
65 unsigned int timeout)
66 {
67 wdd->timeout = timeout;
68
69 return 0;
70 }
71
72 static const struct watchdog_info sun4v_wdt_ident = {
73 .options = WDIOF_SETTIMEOUT |
74 WDIOF_MAGICCLOSE |
75 WDIOF_KEEPALIVEPING,
76 .identity = "sun4v hypervisor watchdog",
77 .firmware_version = 0,
78 };
79
80 static struct watchdog_ops sun4v_wdt_ops = {
81 .owner = THIS_MODULE,
82 .start = sun4v_wdt_ping,
83 .stop = sun4v_wdt_stop,
84 .ping = sun4v_wdt_ping,
85 .set_timeout = sun4v_wdt_set_timeout,
86 };
87
88 static struct watchdog_device wdd = {
89 .info = &sun4v_wdt_ident,
90 .ops = &sun4v_wdt_ops,
91 .min_timeout = WDT_MIN_TIMEOUT,
92 .max_timeout = WDT_MAX_TIMEOUT,
93 .timeout = WDT_TIMEOUT,
94 };
95
sun4v_wdt_init(void)96 static int __init sun4v_wdt_init(void)
97 {
98 struct mdesc_handle *handle;
99 u64 node;
100 const u64 *value;
101 int err = 0;
102 unsigned long major = 1, minor = 1;
103
104 /*
105 * There are 2 properties that can be set from the control
106 * domain for the watchdog.
107 * watchdog-resolution
108 * watchdog-max-timeout
109 *
110 * We can expect a handle to be returned otherwise something
111 * serious is wrong. Correct to return -ENODEV here.
112 */
113
114 handle = mdesc_grab();
115 if (!handle)
116 return -ENODEV;
117
118 node = mdesc_node_by_name(handle, MDESC_NODE_NULL, "platform");
119 err = -ENODEV;
120 if (node == MDESC_NODE_NULL)
121 goto out_release;
122
123 /*
124 * This is a safe way to validate if we are on the right
125 * platform.
126 */
127 if (sun4v_hvapi_register(HV_GRP_CORE, major, &minor))
128 goto out_hv_unreg;
129
130 /* Allow value of watchdog-resolution up to 1s (default) */
131 value = mdesc_get_property(handle, node, "watchdog-resolution", NULL);
132 err = -EINVAL;
133 if (value) {
134 if (*value == 0 ||
135 *value > WDT_DEFAULT_RESOLUTION_MS)
136 goto out_hv_unreg;
137 }
138
139 value = mdesc_get_property(handle, node, "watchdog-max-timeout", NULL);
140 if (value) {
141 /*
142 * If the property value (in ms) is smaller than
143 * min_timeout, return -EINVAL.
144 */
145 if (*value < wdd.min_timeout * 1000)
146 goto out_hv_unreg;
147
148 /*
149 * If the property value is smaller than
150 * default max_timeout then set watchdog max_timeout to
151 * the value of the property in seconds.
152 */
153 if (*value < wdd.max_timeout * 1000)
154 wdd.max_timeout = *value / 1000;
155 }
156
157 watchdog_init_timeout(&wdd, timeout, NULL);
158
159 watchdog_set_nowayout(&wdd, nowayout);
160
161 err = watchdog_register_device(&wdd);
162 if (err)
163 goto out_hv_unreg;
164
165 pr_info("initialized (timeout=%ds, nowayout=%d)\n",
166 wdd.timeout, nowayout);
167
168 mdesc_release(handle);
169
170 return 0;
171
172 out_hv_unreg:
173 sun4v_hvapi_unregister(HV_GRP_CORE);
174
175 out_release:
176 mdesc_release(handle);
177 return err;
178 }
179
sun4v_wdt_exit(void)180 static void __exit sun4v_wdt_exit(void)
181 {
182 sun4v_hvapi_unregister(HV_GRP_CORE);
183 watchdog_unregister_device(&wdd);
184 }
185
186 module_init(sun4v_wdt_init);
187 module_exit(sun4v_wdt_exit);
188
189 MODULE_AUTHOR("Wim Coekaerts <wim.coekaerts@oracle.com>");
190 MODULE_DESCRIPTION("sun4v watchdog driver");
191 MODULE_LICENSE("GPL");
192