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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Xen Watchdog Driver
*
* (c) Copyright 2010 Novell, Inc.
*/
#define DRV_NAME "xen_wdt"
#include <linux/bug.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/hrtimer.h>
#include <linux/kernel.h>
#include <linux/ktime.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/platform_device.h>
#include <linux/watchdog.h>
#include <xen/xen.h>
#include <asm/xen/hypercall.h>
#include <xen/interface/sched.h>
static struct platform_device *platform_device;
static struct sched_watchdog wdt;
static time64_t wdt_expires;
#define WATCHDOG_TIMEOUT 60 /* in seconds */
static unsigned int timeout;
module_param(timeout, uint, S_IRUGO);
MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds "
"(default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, bool, S_IRUGO);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
"(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
static inline time64_t set_timeout(struct watchdog_device *wdd)
{
wdt.timeout = wdd->timeout;
return ktime_get_seconds() + wdd->timeout;
}
static int xen_wdt_start(struct watchdog_device *wdd)
{
time64_t expires;
int err;
expires = set_timeout(wdd);
if (!wdt.id)
err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
else
err = -EBUSY;
if (err > 0) {
wdt.id = err;
wdt_expires = expires;
err = 0;
} else
BUG_ON(!err);
return err;
}
static int xen_wdt_stop(struct watchdog_device *wdd)
{
int err = 0;
wdt.timeout = 0;
if (wdt.id)
err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
if (!err)
wdt.id = 0;
return err;
}
static int xen_wdt_kick(struct watchdog_device *wdd)
{
time64_t expires;
int err;
expires = set_timeout(wdd);
if (wdt.id)
err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
else
err = -ENXIO;
if (!err)
wdt_expires = expires;
return err;
}
static unsigned int xen_wdt_get_timeleft(struct watchdog_device *wdd)
{
return wdt_expires - ktime_get_seconds();
}
static struct watchdog_info xen_wdt_info = {
.identity = DRV_NAME,
.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
};
static const struct watchdog_ops xen_wdt_ops = {
.owner = THIS_MODULE,
.start = xen_wdt_start,
.stop = xen_wdt_stop,
.ping = xen_wdt_kick,
.get_timeleft = xen_wdt_get_timeleft,
};
static struct watchdog_device xen_wdt_dev = {
.info = &xen_wdt_info,
.ops = &xen_wdt_ops,
.timeout = WATCHDOG_TIMEOUT,
};
static int xen_wdt_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct sched_watchdog wd = { .id = ~0 };
int ret = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wd);
if (ret == -ENOSYS) {
dev_err(dev, "watchdog not supported by hypervisor\n");
return -ENODEV;
}
if (ret != -EINVAL) {
dev_err(dev, "unexpected hypervisor error (%d)\n", ret);
return -ENODEV;
}
watchdog_init_timeout(&xen_wdt_dev, timeout, NULL);
watchdog_set_nowayout(&xen_wdt_dev, nowayout);
watchdog_stop_on_reboot(&xen_wdt_dev);
watchdog_stop_on_unregister(&xen_wdt_dev);
ret = devm_watchdog_register_device(dev, &xen_wdt_dev);
if (ret) {
dev_err(dev, "cannot register watchdog device (%d)\n", ret);
return ret;
}
dev_info(dev, "initialized (timeout=%ds, nowayout=%d)\n",
xen_wdt_dev.timeout, nowayout);
return 0;
}
static int xen_wdt_suspend(struct platform_device *dev, pm_message_t state)
{
typeof(wdt.id) id = wdt.id;
int rc = xen_wdt_stop(&xen_wdt_dev);
wdt.id = id;
return rc;
}
static int xen_wdt_resume(struct platform_device *dev)
{
if (!wdt.id)
return 0;
wdt.id = 0;
return xen_wdt_start(&xen_wdt_dev);
}
static struct platform_driver xen_wdt_driver = {
.probe = xen_wdt_probe,
.suspend = xen_wdt_suspend,
.resume = xen_wdt_resume,
.driver = {
.name = DRV_NAME,
},
};
static int __init xen_wdt_init_module(void)
{
int err;
if (!xen_domain())
return -ENODEV;
err = platform_driver_register(&xen_wdt_driver);
if (err)
return err;
platform_device = platform_device_register_simple(DRV_NAME,
-1, NULL, 0);
if (IS_ERR(platform_device)) {
err = PTR_ERR(platform_device);
platform_driver_unregister(&xen_wdt_driver);
}
return err;
}
static void __exit xen_wdt_cleanup_module(void)
{
platform_device_unregister(platform_device);
platform_driver_unregister(&xen_wdt_driver);
}
module_init(xen_wdt_init_module);
module_exit(xen_wdt_cleanup_module);
MODULE_AUTHOR("Jan Beulich <jbeulich@novell.com>");
MODULE_DESCRIPTION("Xen WatchDog Timer Driver");
MODULE_LICENSE("GPL");
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