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");