sun4v_wdt.c
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/*
* sun4v watchdog timer
* (c) Copyright 2016 Oracle Corporation
*
* Implement a simple watchdog driver using the built-in sun4v hypervisor
* watchdog support. If time expires, the hypervisor stops or bounces
* the guest domain.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/watchdog.h>
#include <asm/hypervisor.h>
#include <asm/mdesc.h>
#define WDT_TIMEOUT 60
#define WDT_MAX_TIMEOUT 31536000
#define WDT_MIN_TIMEOUT 1
#define WDT_DEFAULT_RESOLUTION_MS 1000 /* 1 second */
static unsigned int timeout;
module_param(timeout, uint, 0);
MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
__MODULE_STRING(WDT_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 int sun4v_wdt_stop(struct watchdog_device *wdd)
{
sun4v_mach_set_watchdog(0, NULL);
return 0;
}
static int sun4v_wdt_ping(struct watchdog_device *wdd)
{
int hverr;
/*
* HV watchdog timer will round up the timeout
* passed in to the nearest multiple of the
* watchdog resolution in milliseconds.
*/
hverr = sun4v_mach_set_watchdog(wdd->timeout * 1000, NULL);
if (hverr == HV_EINVAL)
return -EINVAL;
return 0;
}
static int sun4v_wdt_set_timeout(struct watchdog_device *wdd,
unsigned int timeout)
{
wdd->timeout = timeout;
return 0;
}
static const struct watchdog_info sun4v_wdt_ident = {
.options = WDIOF_SETTIMEOUT |
WDIOF_MAGICCLOSE |
WDIOF_KEEPALIVEPING,
.identity = "sun4v hypervisor watchdog",
.firmware_version = 0,
};
static const struct watchdog_ops sun4v_wdt_ops = {
.owner = THIS_MODULE,
.start = sun4v_wdt_ping,
.stop = sun4v_wdt_stop,
.ping = sun4v_wdt_ping,
.set_timeout = sun4v_wdt_set_timeout,
};
static struct watchdog_device wdd = {
.info = &sun4v_wdt_ident,
.ops = &sun4v_wdt_ops,
.min_timeout = WDT_MIN_TIMEOUT,
.max_timeout = WDT_MAX_TIMEOUT,
.timeout = WDT_TIMEOUT,
};
static int __init sun4v_wdt_init(void)
{
struct mdesc_handle *handle;
u64 node;
const u64 *value;
int err = 0;
unsigned long major = 1, minor = 1;
/*
* There are 2 properties that can be set from the control
* domain for the watchdog.
* watchdog-resolution
* watchdog-max-timeout
*
* We can expect a handle to be returned otherwise something
* serious is wrong. Correct to return -ENODEV here.
*/
handle = mdesc_grab();
if (!handle)
return -ENODEV;
node = mdesc_node_by_name(handle, MDESC_NODE_NULL, "platform");
err = -ENODEV;
if (node == MDESC_NODE_NULL)
goto out_release;
/*
* This is a safe way to validate if we are on the right
* platform.
*/
if (sun4v_hvapi_register(HV_GRP_CORE, major, &minor))
goto out_hv_unreg;
/* Allow value of watchdog-resolution up to 1s (default) */
value = mdesc_get_property(handle, node, "watchdog-resolution", NULL);
err = -EINVAL;
if (value) {
if (*value == 0 ||
*value > WDT_DEFAULT_RESOLUTION_MS)
goto out_hv_unreg;
}
value = mdesc_get_property(handle, node, "watchdog-max-timeout", NULL);
if (value) {
/*
* If the property value (in ms) is smaller than
* min_timeout, return -EINVAL.
*/
if (*value < wdd.min_timeout * 1000)
goto out_hv_unreg;
/*
* If the property value is smaller than
* default max_timeout then set watchdog max_timeout to
* the value of the property in seconds.
*/
if (*value < wdd.max_timeout * 1000)
wdd.max_timeout = *value / 1000;
}
watchdog_init_timeout(&wdd, timeout, NULL);
watchdog_set_nowayout(&wdd, nowayout);
err = watchdog_register_device(&wdd);
if (err)
goto out_hv_unreg;
pr_info("initialized (timeout=%ds, nowayout=%d)\n",
wdd.timeout, nowayout);
mdesc_release(handle);
return 0;
out_hv_unreg:
sun4v_hvapi_unregister(HV_GRP_CORE);
out_release:
mdesc_release(handle);
return err;
}
static void __exit sun4v_wdt_exit(void)
{
sun4v_hvapi_unregister(HV_GRP_CORE);
watchdog_unregister_device(&wdd);
}
module_init(sun4v_wdt_init);
module_exit(sun4v_wdt_exit);
MODULE_AUTHOR("Wim Coekaerts <wim.coekaerts@oracle.com>");
MODULE_DESCRIPTION("sun4v watchdog driver");
MODULE_LICENSE("GPL");