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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * Xen Watchdog Driver4 *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 else55 err = -EBUSY;56 if (err > 0) {57 wdt.id = err;58 wdt_expires = expires;59 err = 0;60 } else61 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 else88 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");209