Merge remote-tracking branch 'stable/linux-5.15.y' into rpi-5.15.y
[platform/kernel/linux-rpi.git] / drivers / watchdog / xen_wdt.c
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *      Xen Watchdog Driver
4  *
5  *      (c) Copyright 2010 Novell, Inc.
6  */
7
8 #define DRV_NAME        "xen_wdt"
9
10 #include <linux/bug.h>
11 #include <linux/errno.h>
12 #include <linux/fs.h>
13 #include <linux/hrtimer.h>
14 #include <linux/kernel.h>
15 #include <linux/ktime.h>
16 #include <linux/init.h>
17 #include <linux/module.h>
18 #include <linux/moduleparam.h>
19 #include <linux/platform_device.h>
20 #include <linux/watchdog.h>
21 #include <xen/xen.h>
22 #include <asm/xen/hypercall.h>
23 #include <xen/interface/sched.h>
24
25 static struct platform_device *platform_device;
26 static struct sched_watchdog wdt;
27 static time64_t wdt_expires;
28
29 #define WATCHDOG_TIMEOUT 60 /* in seconds */
30 static unsigned int timeout;
31 module_param(timeout, uint, S_IRUGO);
32 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds "
33         "(default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
34
35 static bool nowayout = WATCHDOG_NOWAYOUT;
36 module_param(nowayout, bool, S_IRUGO);
37 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
38         "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
39
40 static inline time64_t set_timeout(struct watchdog_device *wdd)
41 {
42         wdt.timeout = wdd->timeout;
43         return ktime_get_seconds() + wdd->timeout;
44 }
45
46 static int xen_wdt_start(struct watchdog_device *wdd)
47 {
48         time64_t expires;
49         int err;
50
51         expires = set_timeout(wdd);
52         if (!wdt.id)
53                 err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
54         else
55                 err = -EBUSY;
56         if (err > 0) {
57                 wdt.id = err;
58                 wdt_expires = expires;
59                 err = 0;
60         } else
61                 BUG_ON(!err);
62
63         return err;
64 }
65
66 static int xen_wdt_stop(struct watchdog_device *wdd)
67 {
68         int err = 0;
69
70         wdt.timeout = 0;
71         if (wdt.id)
72                 err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
73         if (!err)
74                 wdt.id = 0;
75
76         return err;
77 }
78
79 static int xen_wdt_kick(struct watchdog_device *wdd)
80 {
81         time64_t expires;
82         int err;
83
84         expires = set_timeout(wdd);
85         if (wdt.id)
86                 err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
87         else
88                 err = -ENXIO;
89         if (!err)
90                 wdt_expires = expires;
91
92         return err;
93 }
94
95 static unsigned int xen_wdt_get_timeleft(struct watchdog_device *wdd)
96 {
97         return wdt_expires - ktime_get_seconds();
98 }
99
100 static struct watchdog_info xen_wdt_info = {
101         .identity = DRV_NAME,
102         .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
103 };
104
105 static const struct watchdog_ops xen_wdt_ops = {
106         .owner = THIS_MODULE,
107         .start = xen_wdt_start,
108         .stop = xen_wdt_stop,
109         .ping = xen_wdt_kick,
110         .get_timeleft = xen_wdt_get_timeleft,
111 };
112
113 static struct watchdog_device xen_wdt_dev = {
114         .info = &xen_wdt_info,
115         .ops = &xen_wdt_ops,
116         .timeout = WATCHDOG_TIMEOUT,
117 };
118
119 static int xen_wdt_probe(struct platform_device *pdev)
120 {
121         struct device *dev = &pdev->dev;
122         struct sched_watchdog wd = { .id = ~0 };
123         int ret = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wd);
124
125         if (ret == -ENOSYS) {
126                 dev_err(dev, "watchdog not supported by hypervisor\n");
127                 return -ENODEV;
128         }
129
130         if (ret != -EINVAL) {
131                 dev_err(dev, "unexpected hypervisor error (%d)\n", ret);
132                 return -ENODEV;
133         }
134
135         watchdog_init_timeout(&xen_wdt_dev, timeout, NULL);
136         watchdog_set_nowayout(&xen_wdt_dev, nowayout);
137         watchdog_stop_on_reboot(&xen_wdt_dev);
138         watchdog_stop_on_unregister(&xen_wdt_dev);
139
140         ret = devm_watchdog_register_device(dev, &xen_wdt_dev);
141         if (ret)
142                 return ret;
143
144         dev_info(dev, "initialized (timeout=%ds, nowayout=%d)\n",
145                  xen_wdt_dev.timeout, nowayout);
146
147         return 0;
148 }
149
150 static int xen_wdt_suspend(struct platform_device *dev, pm_message_t state)
151 {
152         typeof(wdt.id) id = wdt.id;
153         int rc = xen_wdt_stop(&xen_wdt_dev);
154
155         wdt.id = id;
156         return rc;
157 }
158
159 static int xen_wdt_resume(struct platform_device *dev)
160 {
161         if (!wdt.id)
162                 return 0;
163         wdt.id = 0;
164         return xen_wdt_start(&xen_wdt_dev);
165 }
166
167 static struct platform_driver xen_wdt_driver = {
168         .probe          = xen_wdt_probe,
169         .suspend        = xen_wdt_suspend,
170         .resume         = xen_wdt_resume,
171         .driver         = {
172                 .name   = DRV_NAME,
173         },
174 };
175
176 static int __init xen_wdt_init_module(void)
177 {
178         int err;
179
180         if (!xen_domain())
181                 return -ENODEV;
182
183         err = platform_driver_register(&xen_wdt_driver);
184         if (err)
185                 return err;
186
187         platform_device = platform_device_register_simple(DRV_NAME,
188                                                                   -1, NULL, 0);
189         if (IS_ERR(platform_device)) {
190                 err = PTR_ERR(platform_device);
191                 platform_driver_unregister(&xen_wdt_driver);
192         }
193
194         return err;
195 }
196
197 static void __exit xen_wdt_cleanup_module(void)
198 {
199         platform_device_unregister(platform_device);
200         platform_driver_unregister(&xen_wdt_driver);
201 }
202
203 module_init(xen_wdt_init_module);
204 module_exit(xen_wdt_cleanup_module);
205
206 MODULE_AUTHOR("Jan Beulich <jbeulich@novell.com>");
207 MODULE_DESCRIPTION("Xen WatchDog Timer Driver");
208 MODULE_LICENSE("GPL");