drivers/watchdog/xen_wdt.c

   1 /*
   2  *      Xen Watchdog Driver
   3  *
   4  *      (c) Copyright 2010 Novell, Inc.
   5  *
   6  *      This program is free software; you can redistribute it and/or
   7  *      modify it under the terms of the GNU General Public License
   8  *      as published by the Free Software Foundation; either version
   9  *      2 of the License, or (at your option) any later version.
  10  */
  11
  12 #define DRV_NAME        "xen_wdt"
  13
  14 #include <linux/bug.h>
  15 #include <linux/errno.h>
  16 #include <linux/fs.h>
  17 #include <linux/hrtimer.h>
  18 #include <linux/kernel.h>
  19 #include <linux/ktime.h>
  20 #include <linux/init.h>
  21 #include <linux/module.h>
  22 #include <linux/moduleparam.h>
  23 #include <linux/platform_device.h>
  24 #include <linux/watchdog.h>
  25 #include <xen/xen.h>
  26 #include <asm/xen/hypercall.h>
  27 #include <xen/interface/sched.h>
  28
  29 static struct platform_device *platform_device;
  30 static struct sched_watchdog wdt;
  31 static time64_t wdt_expires;
  32
  33 #define WATCHDOG_TIMEOUT 60 /* in seconds */
  34 static unsigned int timeout;
  35 module_param(timeout, uint, S_IRUGO);
  36 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds "
  37         "(default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
  38
  39 static bool nowayout = WATCHDOG_NOWAYOUT;
  40 module_param(nowayout, bool, S_IRUGO);
  41 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
  42         "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  43
  44 static inline time64_t set_timeout(struct watchdog_device *wdd)
  45 {
  46         wdt.timeout = wdd->timeout;
  47         return ktime_get_seconds() + wdd->timeout;
  48 }
  49
  50 static int xen_wdt_start(struct watchdog_device *wdd)
  51 {
  52         time64_t expires;
  53         int err;
  54
  55         expires = set_timeout(wdd);
  56         if (!wdt.id)
  57                 err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
  58         else
  59                 err = -EBUSY;
  60         if (err > 0) {
  61                 wdt.id = err;
  62                 wdt_expires = expires;
  63                 err = 0;
  64         } else
  65                 BUG_ON(!err);
  66
  67         return err;
  68 }
  69
  70 static int xen_wdt_stop(struct watchdog_device *wdd)
  71 {
  72         int err = 0;
  73
  74         wdt.timeout = 0;
  75         if (wdt.id)
  76                 err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
  77         if (!err)
  78                 wdt.id = 0;
  79
  80         return err;
  81 }
  82
  83 static int xen_wdt_kick(struct watchdog_device *wdd)
  84 {
  85         time64_t expires;
  86         int err;
  87
  88         expires = set_timeout(wdd);
  89         if (wdt.id)
  90                 err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
  91         else
  92                 err = -ENXIO;
  93         if (!err)
  94                 wdt_expires = expires;
  95
  96         return err;
  97 }
  98
  99 static unsigned int xen_wdt_get_timeleft(struct watchdog_device *wdd)
 100 {
 101         return wdt_expires - ktime_get_seconds();
 102 }
 103
 104 static struct watchdog_info xen_wdt_info = {
 105         .identity = DRV_NAME,
 106         .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 107 };
 108
 109 static const struct watchdog_ops xen_wdt_ops = {
 110         .owner = THIS_MODULE,
 111         .start = xen_wdt_start,
 112         .stop = xen_wdt_stop,
 113         .ping = xen_wdt_kick,
 114         .get_timeleft = xen_wdt_get_timeleft,
 115 };
 116
 117 static struct watchdog_device xen_wdt_dev = {
 118         .info = &xen_wdt_info,
 119         .ops = &xen_wdt_ops,
 120         .timeout = WATCHDOG_TIMEOUT,
 121 };
 122
 123 static int xen_wdt_probe(struct platform_device *pdev)
 124 {
 125         struct sched_watchdog wd = { .id = ~0 };
 126         int ret = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wd);
 127
 128         if (ret == -ENOSYS) {
 129                 dev_err(&pdev->dev, "watchdog not supported by hypervisor\n");
 130                 return -ENODEV;
 131         }
 132
 133         if (ret != -EINVAL) {
 134                 dev_err(&pdev->dev, "unexpected hypervisor error (%d)\n", ret);
 135                 return -ENODEV;
 136         }
 137
 138         if (watchdog_init_timeout(&xen_wdt_dev, timeout, NULL))
 139                 dev_info(&pdev->dev, "timeout value invalid, using %d\n",
 140                         xen_wdt_dev.timeout);
 141         watchdog_set_nowayout(&xen_wdt_dev, nowayout);
 142         watchdog_stop_on_reboot(&xen_wdt_dev);
 143         watchdog_stop_on_unregister(&xen_wdt_dev);
 144
 145         ret = devm_watchdog_register_device(&pdev->dev, &xen_wdt_dev);
 146         if (ret) {
 147                 dev_err(&pdev->dev, "cannot register watchdog device (%d)\n",
 148                         ret);
 149                 return ret;
 150         }
 151
 152         dev_info(&pdev->dev, "initialized (timeout=%ds, nowayout=%d)\n",
 153                 xen_wdt_dev.timeout, nowayout);
 154
 155         return 0;
 156 }
 157
 158 static int xen_wdt_suspend(struct platform_device *dev, pm_message_t state)
 159 {
 160         typeof(wdt.id) id = wdt.id;
 161         int rc = xen_wdt_stop(&xen_wdt_dev);
 162
 163         wdt.id = id;
 164         return rc;
 165 }
 166
 167 static int xen_wdt_resume(struct platform_device *dev)
 168 {
 169         if (!wdt.id)
 170                 return 0;
 171         wdt.id = 0;
 172         return xen_wdt_start(&xen_wdt_dev);
 173 }
 174
 175 static struct platform_driver xen_wdt_driver = {
 176         .probe          = xen_wdt_probe,
 177         .suspend        = xen_wdt_suspend,
 178         .resume         = xen_wdt_resume,
 179         .driver         = {
 180                 .name   = DRV_NAME,
 181         },
 182 };
 183
 184 static int __init xen_wdt_init_module(void)
 185 {
 186         int err;
 187
 188         if (!xen_domain())
 189                 return -ENODEV;
 190
 191         err = platform_driver_register(&xen_wdt_driver);
 192         if (err)
 193                 return err;
 194
 195         platform_device = platform_device_register_simple(DRV_NAME,
 196                                                                   -1, NULL, 0);
 197         if (IS_ERR(platform_device)) {
 198                 err = PTR_ERR(platform_device);
 199                 platform_driver_unregister(&xen_wdt_driver);
 200         }
 201
 202         return err;
 203 }
 204
 205 static void __exit xen_wdt_cleanup_module(void)
 206 {
 207         platform_device_unregister(platform_device);
 208         platform_driver_unregister(&xen_wdt_driver);
 209 }
 210
 211 module_init(xen_wdt_init_module);
 212 module_exit(xen_wdt_cleanup_module);
 213
 214 MODULE_AUTHOR("Jan Beulich <jbeulich@novell.com>");
 215 MODULE_DESCRIPTION("Xen WatchDog Timer Driver");
 216 MODULE_LICENSE("GPL");