xen_wdt.c (4559B)
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 25static struct platform_device *platform_device; 26static struct sched_watchdog wdt; 27static time64_t wdt_expires; 28 29#define WATCHDOG_TIMEOUT 60 /* in seconds */ 30static unsigned int timeout; 31module_param(timeout, uint, S_IRUGO); 32MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds " 33 "(default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")"); 34 35static bool nowayout = WATCHDOG_NOWAYOUT; 36module_param(nowayout, bool, S_IRUGO); 37MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started " 38 "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 39 40static inline time64_t set_timeout(struct watchdog_device *wdd) 41{ 42 wdt.timeout = wdd->timeout; 43 return ktime_get_seconds() + wdd->timeout; 44} 45 46static 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 66static 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 79static 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 95static unsigned int xen_wdt_get_timeleft(struct watchdog_device *wdd) 96{ 97 return wdt_expires - ktime_get_seconds(); 98} 99 100static struct watchdog_info xen_wdt_info = { 101 .identity = DRV_NAME, 102 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE, 103}; 104 105static 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 113static struct watchdog_device xen_wdt_dev = { 114 .info = &xen_wdt_info, 115 .ops = &xen_wdt_ops, 116 .timeout = WATCHDOG_TIMEOUT, 117}; 118 119static 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 150static 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 159static 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 167static 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 176static 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 197static void __exit xen_wdt_cleanup_module(void) 198{ 199 platform_device_unregister(platform_device); 200 platform_driver_unregister(&xen_wdt_driver); 201} 202 203module_init(xen_wdt_init_module); 204module_exit(xen_wdt_cleanup_module); 205 206MODULE_AUTHOR("Jan Beulich <jbeulich@novell.com>"); 207MODULE_DESCRIPTION("Xen WatchDog Timer Driver"); 208MODULE_LICENSE("GPL");