1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * sun4v watchdog timer
4 * (c) Copyright 2016 Oracle Corporation
5 *
6 * Implement a simple watchdog driver using the built-in sun4v hypervisor
7 * watchdog support. If time expires, the hypervisor stops or bounces
8 * the guest domain.
9 */
10
11#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
12
13#include <linux/errno.h>
14#include <linux/init.h>
15#include <linux/kernel.h>
16#include <linux/module.h>
17#include <linux/moduleparam.h>
18#include <linux/watchdog.h>
19#include <asm/hypervisor.h>
20#include <asm/mdesc.h>
21
22#define WDT_TIMEOUT 60
23#define WDT_MAX_TIMEOUT 31536000
24#define WDT_MIN_TIMEOUT 1
25#define WDT_DEFAULT_RESOLUTION_MS 1000 /* 1 second */
26
27static unsigned int timeout;
28module_param(timeout, uint, 0);
29MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
30 __MODULE_STRING(WDT_TIMEOUT) ")");
31
32static bool nowayout = WATCHDOG_NOWAYOUT;
33module_param(nowayout, bool, S_IRUGO);
34MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
35 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
36
37static int sun4v_wdt_stop(struct watchdog_device *wdd)
38{
39 sun4v_mach_set_watchdog(0, NULL);
40
41 return 0;
42}
43
44static int sun4v_wdt_ping(struct watchdog_device *wdd)
45{
46 int hverr;
47
48 /*
49 * HV watchdog timer will round up the timeout
50 * passed in to the nearest multiple of the
51 * watchdog resolution in milliseconds.
52 */
53 hverr = sun4v_mach_set_watchdog(wdd->timeout * 1000, NULL);
54 if (hverr == HV_EINVAL)
55 return -EINVAL;
56
57 return 0;
58}
59
60static int sun4v_wdt_set_timeout(struct watchdog_device *wdd,
61 unsigned int timeout)
62{
63 wdd->timeout = timeout;
64
65 return 0;
66}
67
68static const struct watchdog_info sun4v_wdt_ident = {
69 .options = WDIOF_SETTIMEOUT |
70 WDIOF_MAGICCLOSE |
71 WDIOF_KEEPALIVEPING,
72 .identity = "sun4v hypervisor watchdog",
73 .firmware_version = 0,
74};
75
76static const struct watchdog_ops sun4v_wdt_ops = {
77 .owner = THIS_MODULE,
78 .start = sun4v_wdt_ping,
79 .stop = sun4v_wdt_stop,
80 .ping = sun4v_wdt_ping,
81 .set_timeout = sun4v_wdt_set_timeout,
82};
83
84static struct watchdog_device wdd = {
85 .info = &sun4v_wdt_ident,
86 .ops = &sun4v_wdt_ops,
87 .min_timeout = WDT_MIN_TIMEOUT,
88 .max_timeout = WDT_MAX_TIMEOUT,
89 .timeout = WDT_TIMEOUT,
90};
91
92static int __init sun4v_wdt_init(void)
93{
94 struct mdesc_handle *handle;
95 u64 node;
96 const u64 *value;
97 int err = 0;
98 unsigned long major = 1, minor = 1;
99
100 /*
101 * There are 2 properties that can be set from the control
102 * domain for the watchdog.
103 * watchdog-resolution
104 * watchdog-max-timeout
105 *
106 * We can expect a handle to be returned otherwise something
107 * serious is wrong. Correct to return -ENODEV here.
108 */
109
110 handle = mdesc_grab();
111 if (!handle)
112 return -ENODEV;
113
114 node = mdesc_node_by_name(handle, MDESC_NODE_NULL, "platform");
115 err = -ENODEV;
116 if (node == MDESC_NODE_NULL)
117 goto out_release;
118
119 /*
120 * This is a safe way to validate if we are on the right
121 * platform.
122 */
123 if (sun4v_hvapi_register(HV_GRP_CORE, major, &minor))
124 goto out_hv_unreg;
125
126 /* Allow value of watchdog-resolution up to 1s (default) */
127 value = mdesc_get_property(handle, node, "watchdog-resolution", NULL);
128 err = -EINVAL;
129 if (value) {
130 if (*value == 0 ||
131 *value > WDT_DEFAULT_RESOLUTION_MS)
132 goto out_hv_unreg;
133 }
134
135 value = mdesc_get_property(handle, node, "watchdog-max-timeout", NULL);
136 if (value) {
137 /*
138 * If the property value (in ms) is smaller than
139 * min_timeout, return -EINVAL.
140 */
141 if (*value < wdd.min_timeout * 1000)
142 goto out_hv_unreg;
143
144 /*
145 * If the property value is smaller than
146 * default max_timeout then set watchdog max_timeout to
147 * the value of the property in seconds.
148 */
149 if (*value < wdd.max_timeout * 1000)
150 wdd.max_timeout = *value / 1000;
151 }
152
153 watchdog_init_timeout(wdd: &wdd, timeout_parm: timeout, NULL);
154
155 watchdog_set_nowayout(wdd: &wdd, nowayout);
156
157 err = watchdog_register_device(&wdd);
158 if (err)
159 goto out_hv_unreg;
160
161 pr_info("initialized (timeout=%ds, nowayout=%d)\n",
162 wdd.timeout, nowayout);
163
164 mdesc_release(handle);
165
166 return 0;
167
168out_hv_unreg:
169 sun4v_hvapi_unregister(HV_GRP_CORE);
170
171out_release:
172 mdesc_release(handle);
173 return err;
174}
175
176static void __exit sun4v_wdt_exit(void)
177{
178 sun4v_hvapi_unregister(HV_GRP_CORE);
179 watchdog_unregister_device(&wdd);
180}
181
182module_init(sun4v_wdt_init);
183module_exit(sun4v_wdt_exit);
184
185MODULE_AUTHOR("Wim Coekaerts <wim.coekaerts@oracle.com>");
186MODULE_DESCRIPTION("sun4v watchdog driver");
187MODULE_LICENSE("GPL");
188

source code of linux/drivers/watchdog/sun4v_wdt.c