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 dev_err(dev, "cannot register watchdog device (%d)\n", ret); 143 return ret; 144 } 145 146 dev_info(dev, "initialized (timeout=%ds, nowayout=%d)\n", 147 xen_wdt_dev.timeout, nowayout); 148 149 return 0; 150 } 151 152 static int xen_wdt_suspend(struct platform_device *dev, pm_message_t state) 153 { 154 typeof(wdt.id) id = wdt.id; 155 int rc = xen_wdt_stop(&xen_wdt_dev); 156 157 wdt.id = id; 158 return rc; 159 } 160 161 static int xen_wdt_resume(struct platform_device *dev) 162 { 163 if (!wdt.id) 164 return 0; 165 wdt.id = 0; 166 return xen_wdt_start(&xen_wdt_dev); 167 } 168 169 static struct platform_driver xen_wdt_driver = { 170 .probe = xen_wdt_probe, 171 .suspend = xen_wdt_suspend, 172 .resume = xen_wdt_resume, 173 .driver = { 174 .name = DRV_NAME, 175 }, 176 }; 177 178 static int __init xen_wdt_init_module(void) 179 { 180 int err; 181 182 if (!xen_domain()) 183 return -ENODEV; 184 185 err = platform_driver_register(&xen_wdt_driver); 186 if (err) 187 return err; 188 189 platform_device = platform_device_register_simple(DRV_NAME, 190 -1, NULL, 0); 191 if (IS_ERR(platform_device)) { 192 err = PTR_ERR(platform_device); 193 platform_driver_unregister(&xen_wdt_driver); 194 } 195 196 return err; 197 } 198 199 static void __exit xen_wdt_cleanup_module(void) 200 { 201 platform_device_unregister(platform_device); 202 platform_driver_unregister(&xen_wdt_driver); 203 } 204 205 module_init(xen_wdt_init_module); 206 module_exit(xen_wdt_cleanup_module); 207 208 MODULE_AUTHOR("Jan Beulich <jbeulich@novell.com>"); 209 MODULE_DESCRIPTION("Xen WatchDog Timer Driver"); 210 MODULE_LICENSE("GPL"); 211