linux/drivers/watchdog/xen_wdt.c
Jean Delvare 487722cf2d watchdog: Get rid of MODULE_ALIAS_MISCDEV statements
I just can't find any value in MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR)
and MODULE_ALIAS_MISCDEV(TEMP_MINOR) statements.

Either the device is enumerated and the driver already has a module
alias (e.g. PCI, USB etc.) that will get the right driver loaded
automatically.

Or the device is not enumerated and loading its driver will lead to
more or less intrusive hardware poking. Such hardware poking should be
limited to a bare minimum, so the user should really decide which
drivers should be tried and in what order. Trying them all in
arbitrary order can't do any good.

On top of that, loading that many drivers at once bloats the kernel
log. Also many drivers will stay loaded afterward, bloating the output
of "lsmod" and wasting memory. Some modules (cs5535_mfgpt which gets
loaded as a dependency) can't even be unloaded!

If defining char-major-10-130 is needed then it should happen in
user-space.

Signed-off-by: Jean Delvare <jdelvare@suse.de>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Cc: Stephen Warren <swarren@wwwdotorg.org>
Cc: Mike Frysinger <vapier.adi@gmail.com>
Cc: Wan ZongShun <mcuos.com@gmail.com>
Cc: Ben Dooks <ben-linux@fluff.org>
Cc: Kukjin Kim <kgene.kim@samsung.com>
Cc: Zwane Mwaikambo <zwane@arm.linux.org.uk>
Cc: Jim Cromie <jim.cromie@gmail.com>
2013-11-17 19:38:13 +01:00

365 lines
7.5 KiB
C

/*
* Xen Watchdog Driver
*
* (c) Copyright 2010 Novell, Inc.
*
* 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
#define DRV_NAME "wdt"
#define DRV_VERSION "0.01"
#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/miscdevice.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/platform_device.h>
#include <linux/spinlock.h>
#include <linux/uaccess.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 DEFINE_SPINLOCK(wdt_lock);
static struct sched_watchdog wdt;
static __kernel_time_t wdt_expires;
static bool is_active, expect_release;
#define WATCHDOG_TIMEOUT 60 /* in seconds */
static unsigned int timeout = WATCHDOG_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 __kernel_time_t set_timeout(void)
{
wdt.timeout = timeout;
return ktime_to_timespec(ktime_get()).tv_sec + timeout;
}
static int xen_wdt_start(void)
{
__kernel_time_t expires;
int err;
spin_lock(&wdt_lock);
expires = set_timeout();
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);
spin_unlock(&wdt_lock);
return err;
}
static int xen_wdt_stop(void)
{
int err = 0;
spin_lock(&wdt_lock);
wdt.timeout = 0;
if (wdt.id)
err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
if (!err)
wdt.id = 0;
spin_unlock(&wdt_lock);
return err;
}
static int xen_wdt_kick(void)
{
__kernel_time_t expires;
int err;
spin_lock(&wdt_lock);
expires = set_timeout();
if (wdt.id)
err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
else
err = -ENXIO;
if (!err)
wdt_expires = expires;
spin_unlock(&wdt_lock);
return err;
}
static int xen_wdt_open(struct inode *inode, struct file *file)
{
int err;
/* /dev/watchdog can only be opened once */
if (xchg(&is_active, true))
return -EBUSY;
err = xen_wdt_start();
if (err == -EBUSY)
err = xen_wdt_kick();
return err ?: nonseekable_open(inode, file);
}
static int xen_wdt_release(struct inode *inode, struct file *file)
{
int err = 0;
if (expect_release)
err = xen_wdt_stop();
else {
pr_crit("unexpected close, not stopping watchdog!\n");
xen_wdt_kick();
}
is_active = err;
expect_release = false;
return err;
}
static ssize_t xen_wdt_write(struct file *file, const char __user *data,
size_t len, loff_t *ppos)
{
/* See if we got the magic character 'V' and reload the timer */
if (len) {
if (!nowayout) {
size_t i;
/* in case it was set long ago */
expect_release = false;
/* scan to see whether or not we got the magic
character */
for (i = 0; i != len; i++) {
char c;
if (get_user(c, data + i))
return -EFAULT;
if (c == 'V')
expect_release = true;
}
}
/* someone wrote to us, we should reload the timer */
xen_wdt_kick();
}
return len;
}
static long xen_wdt_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
int new_options, retval = -EINVAL;
int new_timeout;
int __user *argp = (void __user *)arg;
static const struct watchdog_info ident = {
.options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
.firmware_version = 0,
.identity = DRV_NAME,
};
switch (cmd) {
case WDIOC_GETSUPPORT:
return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
case WDIOC_GETSTATUS:
case WDIOC_GETBOOTSTATUS:
return put_user(0, argp);
case WDIOC_SETOPTIONS:
if (get_user(new_options, argp))
return -EFAULT;
if (new_options & WDIOS_DISABLECARD)
retval = xen_wdt_stop();
if (new_options & WDIOS_ENABLECARD) {
retval = xen_wdt_start();
if (retval == -EBUSY)
retval = xen_wdt_kick();
}
return retval;
case WDIOC_KEEPALIVE:
xen_wdt_kick();
return 0;
case WDIOC_SETTIMEOUT:
if (get_user(new_timeout, argp))
return -EFAULT;
if (!new_timeout)
return -EINVAL;
timeout = new_timeout;
xen_wdt_kick();
/* fall through */
case WDIOC_GETTIMEOUT:
return put_user(timeout, argp);
case WDIOC_GETTIMELEFT:
retval = wdt_expires - ktime_to_timespec(ktime_get()).tv_sec;
return put_user(retval, argp);
}
return -ENOTTY;
}
static const struct file_operations xen_wdt_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
.write = xen_wdt_write,
.unlocked_ioctl = xen_wdt_ioctl,
.open = xen_wdt_open,
.release = xen_wdt_release,
};
static struct miscdevice xen_wdt_miscdev = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &xen_wdt_fops,
};
static int xen_wdt_probe(struct platform_device *dev)
{
struct sched_watchdog wd = { .id = ~0 };
int ret = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wd);
switch (ret) {
case -EINVAL:
if (!timeout) {
timeout = WATCHDOG_TIMEOUT;
pr_info("timeout value invalid, using %d\n", timeout);
}
ret = misc_register(&xen_wdt_miscdev);
if (ret) {
pr_err("cannot register miscdev on minor=%d (%d)\n",
WATCHDOG_MINOR, ret);
break;
}
pr_info("initialized (timeout=%ds, nowayout=%d)\n",
timeout, nowayout);
break;
case -ENOSYS:
pr_info("not supported\n");
ret = -ENODEV;
break;
default:
pr_info("bogus return value %d\n", ret);
break;
}
return ret;
}
static int xen_wdt_remove(struct platform_device *dev)
{
/* Stop the timer before we leave */
if (!nowayout)
xen_wdt_stop();
misc_deregister(&xen_wdt_miscdev);
return 0;
}
static void xen_wdt_shutdown(struct platform_device *dev)
{
xen_wdt_stop();
}
static int xen_wdt_suspend(struct platform_device *dev, pm_message_t state)
{
typeof(wdt.id) id = wdt.id;
int rc = xen_wdt_stop();
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();
}
static struct platform_driver xen_wdt_driver = {
.probe = xen_wdt_probe,
.remove = xen_wdt_remove,
.shutdown = xen_wdt_shutdown,
.suspend = xen_wdt_suspend,
.resume = xen_wdt_resume,
.driver = {
.owner = THIS_MODULE,
.name = DRV_NAME,
},
};
static int __init xen_wdt_init_module(void)
{
int err;
if (!xen_domain())
return -ENODEV;
pr_info("Xen WatchDog Timer Driver v%s\n", DRV_VERSION);
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);
pr_info("module unloaded\n");
}
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_VERSION(DRV_VERSION);
MODULE_LICENSE("GPL");