linux-stable/drivers/watchdog/watchdog_core.c
Justin Chen 9dd4e173f7 watchdog: watchdog_dev: Use device tree alias for naming watchdogs
Currently there is no way to easily differentiate multiple
watchdog devices. The watchdogs are named by the order they
are probed.
1st probed watchdog: /dev/watchdog0
2nd probed watchdog: /dev/watchdog1
...

This change uses the alias of the watchdog device node for
the name of the watchdog.
aliases {
    watchdog0 = "/...../...."
    watchdog3 = "/..../....."
    watchdog2 = "/..../....."
    ...
}

This will translate to...
/dev/watchdog0
/dev/watchdog3
/dev/watchdog2

v2
Assign alias number to id in watchdog_core instead of watchdog_dev.
If failed to get id, fallback to original ida_simple_get call.

Signed-off-by: Justin Chen <justinpopo6@gmail.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
2015-10-27 16:49:57 +01:00

319 lines
8.5 KiB
C

/*
* watchdog_core.c
*
* (c) Copyright 2008-2011 Alan Cox <alan@lxorguk.ukuu.org.uk>,
* All Rights Reserved.
*
* (c) Copyright 2008-2011 Wim Van Sebroeck <wim@iguana.be>.
*
* This source code is part of the generic code that can be used
* by all the watchdog timer drivers.
*
* Based on source code of the following authors:
* Matt Domsch <Matt_Domsch@dell.com>,
* Rob Radez <rob@osinvestor.com>,
* Rusty Lynch <rusty@linux.co.intel.com>
* Satyam Sharma <satyam@infradead.org>
* Randy Dunlap <randy.dunlap@oracle.com>
*
* 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.
*
* Neither Alan Cox, CymruNet Ltd., Wim Van Sebroeck nor Iguana vzw.
* admit liability nor provide warranty for any of this software.
* This material is provided "AS-IS" and at no charge.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h> /* For EXPORT_SYMBOL/module stuff/... */
#include <linux/types.h> /* For standard types */
#include <linux/errno.h> /* For the -ENODEV/... values */
#include <linux/kernel.h> /* For printk/panic/... */
#include <linux/watchdog.h> /* For watchdog specific items */
#include <linux/init.h> /* For __init/__exit/... */
#include <linux/idr.h> /* For ida_* macros */
#include <linux/err.h> /* For IS_ERR macros */
#include <linux/of.h> /* For of_get_timeout_sec */
#include "watchdog_core.h" /* For watchdog_dev_register/... */
static DEFINE_IDA(watchdog_ida);
static struct class *watchdog_class;
/*
* Deferred Registration infrastructure.
*
* Sometimes watchdog drivers needs to be loaded as soon as possible,
* for example when it's impossible to disable it. To do so,
* raising the initcall level of the watchdog driver is a solution.
* But in such case, the miscdev is maybe not ready (subsys_initcall), and
* watchdog_core need miscdev to register the watchdog as a char device.
*
* The deferred registration infrastructure offer a way for the watchdog
* subsystem to register a watchdog properly, even before miscdev is ready.
*/
static DEFINE_MUTEX(wtd_deferred_reg_mutex);
static LIST_HEAD(wtd_deferred_reg_list);
static bool wtd_deferred_reg_done;
static int watchdog_deferred_registration_add(struct watchdog_device *wdd)
{
list_add_tail(&wdd->deferred,
&wtd_deferred_reg_list);
return 0;
}
static void watchdog_deferred_registration_del(struct watchdog_device *wdd)
{
struct list_head *p, *n;
struct watchdog_device *wdd_tmp;
list_for_each_safe(p, n, &wtd_deferred_reg_list) {
wdd_tmp = list_entry(p, struct watchdog_device,
deferred);
if (wdd_tmp == wdd) {
list_del(&wdd_tmp->deferred);
break;
}
}
}
static void watchdog_check_min_max_timeout(struct watchdog_device *wdd)
{
/*
* Check that we have valid min and max timeout values, if
* not reset them both to 0 (=not used or unknown)
*/
if (wdd->min_timeout > wdd->max_timeout) {
pr_info("Invalid min and max timeout values, resetting to 0!\n");
wdd->min_timeout = 0;
wdd->max_timeout = 0;
}
}
/**
* watchdog_init_timeout() - initialize the timeout field
* @timeout_parm: timeout module parameter
* @dev: Device that stores the timeout-sec property
*
* Initialize the timeout field of the watchdog_device struct with either the
* timeout module parameter (if it is valid value) or the timeout-sec property
* (only if it is a valid value and the timeout_parm is out of bounds).
* If none of them are valid then we keep the old value (which should normally
* be the default timeout value.
*
* A zero is returned on success and -EINVAL for failure.
*/
int watchdog_init_timeout(struct watchdog_device *wdd,
unsigned int timeout_parm, struct device *dev)
{
unsigned int t = 0;
int ret = 0;
watchdog_check_min_max_timeout(wdd);
/* try to get the timeout module parameter first */
if (!watchdog_timeout_invalid(wdd, timeout_parm) && timeout_parm) {
wdd->timeout = timeout_parm;
return ret;
}
if (timeout_parm)
ret = -EINVAL;
/* try to get the timeout_sec property */
if (dev == NULL || dev->of_node == NULL)
return ret;
of_property_read_u32(dev->of_node, "timeout-sec", &t);
if (!watchdog_timeout_invalid(wdd, t) && t)
wdd->timeout = t;
else
ret = -EINVAL;
return ret;
}
EXPORT_SYMBOL_GPL(watchdog_init_timeout);
static int __watchdog_register_device(struct watchdog_device *wdd)
{
int ret, id = -1, devno;
if (wdd == NULL || wdd->info == NULL || wdd->ops == NULL)
return -EINVAL;
/* Mandatory operations need to be supported */
if (wdd->ops->start == NULL || wdd->ops->stop == NULL)
return -EINVAL;
watchdog_check_min_max_timeout(wdd);
/*
* Note: now that all watchdog_device data has been verified, we
* will not check this anymore in other functions. If data gets
* corrupted in a later stage then we expect a kernel panic!
*/
mutex_init(&wdd->lock);
/* Use alias for watchdog id if possible */
if (wdd->parent) {
ret = of_alias_get_id(wdd->parent->of_node, "watchdog");
if (ret >= 0)
id = ida_simple_get(&watchdog_ida, ret,
ret + 1, GFP_KERNEL);
}
if (id < 0)
id = ida_simple_get(&watchdog_ida, 0, MAX_DOGS, GFP_KERNEL);
if (id < 0)
return id;
wdd->id = id;
ret = watchdog_dev_register(wdd);
if (ret) {
ida_simple_remove(&watchdog_ida, id);
if (!(id == 0 && ret == -EBUSY))
return ret;
/* Retry in case a legacy watchdog module exists */
id = ida_simple_get(&watchdog_ida, 1, MAX_DOGS, GFP_KERNEL);
if (id < 0)
return id;
wdd->id = id;
ret = watchdog_dev_register(wdd);
if (ret) {
ida_simple_remove(&watchdog_ida, id);
return ret;
}
}
devno = wdd->cdev.dev;
wdd->dev = device_create(watchdog_class, wdd->parent, devno,
NULL, "watchdog%d", wdd->id);
if (IS_ERR(wdd->dev)) {
watchdog_dev_unregister(wdd);
ida_simple_remove(&watchdog_ida, id);
ret = PTR_ERR(wdd->dev);
return ret;
}
return 0;
}
/**
* watchdog_register_device() - register a watchdog device
* @wdd: watchdog device
*
* Register a watchdog device with the kernel so that the
* watchdog timer can be accessed from userspace.
*
* A zero is returned on success and a negative errno code for
* failure.
*/
int watchdog_register_device(struct watchdog_device *wdd)
{
int ret;
mutex_lock(&wtd_deferred_reg_mutex);
if (wtd_deferred_reg_done)
ret = __watchdog_register_device(wdd);
else
ret = watchdog_deferred_registration_add(wdd);
mutex_unlock(&wtd_deferred_reg_mutex);
return ret;
}
EXPORT_SYMBOL_GPL(watchdog_register_device);
static void __watchdog_unregister_device(struct watchdog_device *wdd)
{
int ret;
int devno;
if (wdd == NULL)
return;
devno = wdd->cdev.dev;
ret = watchdog_dev_unregister(wdd);
if (ret)
pr_err("error unregistering /dev/watchdog (err=%d)\n", ret);
device_destroy(watchdog_class, devno);
ida_simple_remove(&watchdog_ida, wdd->id);
wdd->dev = NULL;
}
/**
* watchdog_unregister_device() - unregister a watchdog device
* @wdd: watchdog device to unregister
*
* Unregister a watchdog device that was previously successfully
* registered with watchdog_register_device().
*/
void watchdog_unregister_device(struct watchdog_device *wdd)
{
mutex_lock(&wtd_deferred_reg_mutex);
if (wtd_deferred_reg_done)
__watchdog_unregister_device(wdd);
else
watchdog_deferred_registration_del(wdd);
mutex_unlock(&wtd_deferred_reg_mutex);
}
EXPORT_SYMBOL_GPL(watchdog_unregister_device);
static int __init watchdog_deferred_registration(void)
{
mutex_lock(&wtd_deferred_reg_mutex);
wtd_deferred_reg_done = true;
while (!list_empty(&wtd_deferred_reg_list)) {
struct watchdog_device *wdd;
wdd = list_first_entry(&wtd_deferred_reg_list,
struct watchdog_device, deferred);
list_del(&wdd->deferred);
__watchdog_register_device(wdd);
}
mutex_unlock(&wtd_deferred_reg_mutex);
return 0;
}
static int __init watchdog_init(void)
{
int err;
watchdog_class = class_create(THIS_MODULE, "watchdog");
if (IS_ERR(watchdog_class)) {
pr_err("couldn't create class\n");
return PTR_ERR(watchdog_class);
}
err = watchdog_dev_init();
if (err < 0) {
class_destroy(watchdog_class);
return err;
}
watchdog_deferred_registration();
return 0;
}
static void __exit watchdog_exit(void)
{
watchdog_dev_exit();
class_destroy(watchdog_class);
ida_destroy(&watchdog_ida);
}
subsys_initcall_sync(watchdog_init);
module_exit(watchdog_exit);
MODULE_AUTHOR("Alan Cox <alan@lxorguk.ukuu.org.uk>");
MODULE_AUTHOR("Wim Van Sebroeck <wim@iguana.be>");
MODULE_DESCRIPTION("WatchDog Timer Driver Core");
MODULE_LICENSE("GPL");