drivers/watchdog/xen_wdt.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  *  Xen Watchdog Driver
0004  *
0005  *  (c) Copyright 2010 Novell, Inc.
0006  */
0007
0008 #define DRV_NAME    "xen_wdt"
0009
0010 #include <linux/bug.h>
0011 #include <linux/errno.h>
0012 #include <linux/fs.h>
0013 #include <linux/hrtimer.h>
0014 #include <linux/kernel.h>
0015 #include <linux/ktime.h>
0016 #include <linux/init.h>
0017 #include <linux/module.h>
0018 #include <linux/moduleparam.h>
0019 #include <linux/platform_device.h>
0020 #include <linux/watchdog.h>
0021 #include <xen/xen.h>
0022 #include <asm/xen/hypercall.h>
0023 #include <xen/interface/sched.h>
0024
0025 static struct platform_device *platform_device;
0026 static struct sched_watchdog wdt;
0027 static time64_t wdt_expires;
0028
0029 #define WATCHDOG_TIMEOUT 60 /* in seconds */
0030 static unsigned int timeout;
0031 module_param(timeout, uint, S_IRUGO);
0032 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds "
0033     "(default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
0034
0035 static bool nowayout = WATCHDOG_NOWAYOUT;
0036 module_param(nowayout, bool, S_IRUGO);
0037 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
0038     "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
0039
0040 static inline time64_t set_timeout(struct watchdog_device *wdd)
0041 {
0042     wdt.timeout = wdd->timeout;
0043     return ktime_get_seconds() + wdd->timeout;
0044 }
0045
0046 static int xen_wdt_start(struct watchdog_device *wdd)
0047 {
0048     time64_t expires;
0049     int err;
0050
0051     expires = set_timeout(wdd);
0052     if (!wdt.id)
0053         err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
0054     else
0055         err = -EBUSY;
0056     if (err > 0) {
0057         wdt.id = err;
0058         wdt_expires = expires;
0059         err = 0;
0060     } else
0061         BUG_ON(!err);
0062
0063     return err;
0064 }
0065
0066 static int xen_wdt_stop(struct watchdog_device *wdd)
0067 {
0068     int err = 0;
0069
0070     wdt.timeout = 0;
0071     if (wdt.id)
0072         err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
0073     if (!err)
0074         wdt.id = 0;
0075
0076     return err;
0077 }
0078
0079 static int xen_wdt_kick(struct watchdog_device *wdd)
0080 {
0081     time64_t expires;
0082     int err;
0083
0084     expires = set_timeout(wdd);
0085     if (wdt.id)
0086         err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
0087     else
0088         err = -ENXIO;
0089     if (!err)
0090         wdt_expires = expires;
0091
0092     return err;
0093 }
0094
0095 static unsigned int xen_wdt_get_timeleft(struct watchdog_device *wdd)
0096 {
0097     return wdt_expires - ktime_get_seconds();
0098 }
0099
0100 static struct watchdog_info xen_wdt_info = {
0101     .identity = DRV_NAME,
0102     .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
0103 };
0104
0105 static const struct watchdog_ops xen_wdt_ops = {
0106     .owner = THIS_MODULE,
0107     .start = xen_wdt_start,
0108     .stop = xen_wdt_stop,
0109     .ping = xen_wdt_kick,
0110     .get_timeleft = xen_wdt_get_timeleft,
0111 };
0112
0113 static struct watchdog_device xen_wdt_dev = {
0114     .info = &xen_wdt_info,
0115     .ops = &xen_wdt_ops,
0116     .timeout = WATCHDOG_TIMEOUT,
0117 };
0118
0119 static int xen_wdt_probe(struct platform_device *pdev)
0120 {
0121     struct device *dev = &pdev->dev;
0122     struct sched_watchdog wd = { .id = ~0 };
0123     int ret = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wd);
0124
0125     if (ret == -ENOSYS) {
0126         dev_err(dev, "watchdog not supported by hypervisor\n");
0127         return -ENODEV;
0128     }
0129
0130     if (ret != -EINVAL) {
0131         dev_err(dev, "unexpected hypervisor error (%d)\n", ret);
0132         return -ENODEV;
0133     }
0134
0135     watchdog_init_timeout(&xen_wdt_dev, timeout, NULL);
0136     watchdog_set_nowayout(&xen_wdt_dev, nowayout);
0137     watchdog_stop_on_reboot(&xen_wdt_dev);
0138     watchdog_stop_on_unregister(&xen_wdt_dev);
0139
0140     ret = devm_watchdog_register_device(dev, &xen_wdt_dev);
0141     if (ret)
0142         return ret;
0143
0144     dev_info(dev, "initialized (timeout=%ds, nowayout=%d)\n",
0145          xen_wdt_dev.timeout, nowayout);
0146
0147     return 0;
0148 }
0149
0150 static int xen_wdt_suspend(struct platform_device *dev, pm_message_t state)
0151 {
0152     typeof(wdt.id) id = wdt.id;
0153     int rc = xen_wdt_stop(&xen_wdt_dev);
0154
0155     wdt.id = id;
0156     return rc;
0157 }
0158
0159 static int xen_wdt_resume(struct platform_device *dev)
0160 {
0161     if (!wdt.id)
0162         return 0;
0163     wdt.id = 0;
0164     return xen_wdt_start(&xen_wdt_dev);
0165 }
0166
0167 static struct platform_driver xen_wdt_driver = {
0168     .probe          = xen_wdt_probe,
0169     .suspend        = xen_wdt_suspend,
0170     .resume         = xen_wdt_resume,
0171     .driver         = {
0172         .name   = DRV_NAME,
0173     },
0174 };
0175
0176 static int __init xen_wdt_init_module(void)
0177 {
0178     int err;
0179
0180     if (!xen_domain())
0181         return -ENODEV;
0182
0183     err = platform_driver_register(&xen_wdt_driver);
0184     if (err)
0185         return err;
0186
0187     platform_device = platform_device_register_simple(DRV_NAME,
0188                                   -1, NULL, 0);
0189     if (IS_ERR(platform_device)) {
0190         err = PTR_ERR(platform_device);
0191         platform_driver_unregister(&xen_wdt_driver);
0192     }
0193
0194     return err;
0195 }
0196
0197 static void __exit xen_wdt_cleanup_module(void)
0198 {
0199     platform_device_unregister(platform_device);
0200     platform_driver_unregister(&xen_wdt_driver);
0201 }
0202
0203 module_init(xen_wdt_init_module);
0204 module_exit(xen_wdt_cleanup_module);
0205
0206 MODULE_AUTHOR("Jan Beulich <jbeulich@novell.com>");
0207 MODULE_DESCRIPTION("Xen WatchDog Timer Driver");
0208 MODULE_LICENSE("GPL");