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"); 217