linux/drivers/watchdog/acquirewdt.c
Uwe Kleine-König 88d2c181ee watchdog: acquirewdt: Convert to platform remove callback returning void
The .remove() callback for a platform driver returns an int which makes
many driver authors wrongly assume it's possible to do error handling by
returning an error code. However the value returned is (mostly) ignored
and this typically results in resource leaks. To improve here there is a
quest to make the remove callback return void. In the first step of this
quest all drivers are converted to .remove_new() which already returns
void.

Trivially convert this driver from always returning zero in the remove
callback to the void returning variant.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20230303213716.2123717-3-u.kleine-koenig@pengutronix.de
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>
2023-04-22 12:53:40 +02:00

330 lines
8.3 KiB
C

// SPDX-License-Identifier: GPL-2.0+
/*
* Acquire Single Board Computer Watchdog Timer driver
*
* Based on wdt.c. Original copyright messages:
*
* (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
* All Rights Reserved.
*
* Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
* warranty for any of this software. This material is provided
* "AS-IS" and at no charge.
*
* (c) Copyright 1995 Alan Cox <alan@lxorguk.ukuu.org.uk>
*
* 14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
* Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
* Can't add timeout - driver doesn't allow changing value
*/
/*
* Theory of Operation:
* The Watch-Dog Timer is provided to ensure that standalone
* Systems can always recover from catastrophic conditions that
* caused the CPU to crash. This condition may have occurred by
* external EMI or a software bug. When the CPU stops working
* correctly, hardware on the board will either perform a hardware
* reset (cold boot) or a non-maskable interrupt (NMI) to bring the
* system back to a known state.
*
* The Watch-Dog Timer is controlled by two I/O Ports.
* 443 hex - Read - Enable or refresh the Watch-Dog Timer
* 043 hex - Read - Disable the Watch-Dog Timer
*
* To enable the Watch-Dog Timer, a read from I/O port 443h must
* be performed. This will enable and activate the countdown timer
* which will eventually time out and either reset the CPU or cause
* an NMI depending on the setting of a jumper. To ensure that this
* reset condition does not occur, the Watch-Dog Timer must be
* periodically refreshed by reading the same I/O port 443h.
* The Watch-Dog Timer is disabled by reading I/O port 043h.
*
* The Watch-Dog Timer Time-Out Period is set via jumpers.
* It can be 1, 2, 10, 20, 110 or 220 seconds.
*/
/*
* Includes, defines, variables, module parameters, ...
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
/* Includes */
#include <linux/module.h> /* For module specific items */
#include <linux/moduleparam.h> /* For new moduleparam's */
#include <linux/types.h> /* For standard types (like size_t) */
#include <linux/errno.h> /* For the -ENODEV/... values */
#include <linux/kernel.h> /* For printk/panic/... */
#include <linux/miscdevice.h> /* For struct miscdevice */
#include <linux/watchdog.h> /* For the watchdog specific items */
#include <linux/fs.h> /* For file operations */
#include <linux/ioport.h> /* For io-port access */
#include <linux/platform_device.h> /* For platform_driver framework */
#include <linux/init.h> /* For __init/__exit/... */
#include <linux/uaccess.h> /* For copy_to_user/put_user/... */
#include <linux/io.h> /* For inb/outb/... */
/* Module information */
#define DRV_NAME "acquirewdt"
#define WATCHDOG_NAME "Acquire WDT"
/* There is no way to see what the correct time-out period is */
#define WATCHDOG_HEARTBEAT 0
/* internal variables */
/* the watchdog platform device */
static struct platform_device *acq_platform_device;
static unsigned long acq_is_open;
static char expect_close;
/* module parameters */
/* You must set this - there is no sane way to probe for this board. */
static int wdt_stop = 0x43;
module_param(wdt_stop, int, 0);
MODULE_PARM_DESC(wdt_stop, "Acquire WDT 'stop' io port (default 0x43)");
/* You must set this - there is no sane way to probe for this board. */
static int wdt_start = 0x443;
module_param(wdt_start, int, 0);
MODULE_PARM_DESC(wdt_start, "Acquire WDT 'start' io port (default 0x443)");
static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout,
"Watchdog cannot be stopped once started (default="
__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
/*
* Watchdog Operations
*/
static void acq_keepalive(void)
{
/* Write a watchdog value */
inb_p(wdt_start);
}
static void acq_stop(void)
{
/* Turn the card off */
inb_p(wdt_stop);
}
/*
* /dev/watchdog handling
*/
static ssize_t acq_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
/* See if we got the magic character 'V' and reload the timer */
if (count) {
if (!nowayout) {
size_t i;
/* note: just in case someone wrote the magic character
five months ago... */
expect_close = 0;
/* scan to see whether or not we got the
magic character */
for (i = 0; i != count; i++) {
char c;
if (get_user(c, buf + i))
return -EFAULT;
if (c == 'V')
expect_close = 42;
}
}
/* Well, anyhow someone wrote to us, we should
return that favour */
acq_keepalive();
}
return count;
}
static long acq_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
int options, retval = -EINVAL;
void __user *argp = (void __user *)arg;
int __user *p = argp;
static const struct watchdog_info ident = {
.options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
.firmware_version = 1,
.identity = WATCHDOG_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, p);
case WDIOC_SETOPTIONS:
{
if (get_user(options, p))
return -EFAULT;
if (options & WDIOS_DISABLECARD) {
acq_stop();
retval = 0;
}
if (options & WDIOS_ENABLECARD) {
acq_keepalive();
retval = 0;
}
return retval;
}
case WDIOC_KEEPALIVE:
acq_keepalive();
return 0;
case WDIOC_GETTIMEOUT:
return put_user(WATCHDOG_HEARTBEAT, p);
default:
return -ENOTTY;
}
}
static int acq_open(struct inode *inode, struct file *file)
{
if (test_and_set_bit(0, &acq_is_open))
return -EBUSY;
if (nowayout)
__module_get(THIS_MODULE);
/* Activate */
acq_keepalive();
return stream_open(inode, file);
}
static int acq_close(struct inode *inode, struct file *file)
{
if (expect_close == 42) {
acq_stop();
} else {
pr_crit("Unexpected close, not stopping watchdog!\n");
acq_keepalive();
}
clear_bit(0, &acq_is_open);
expect_close = 0;
return 0;
}
/*
* Kernel Interfaces
*/
static const struct file_operations acq_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
.write = acq_write,
.unlocked_ioctl = acq_ioctl,
.compat_ioctl = compat_ptr_ioctl,
.open = acq_open,
.release = acq_close,
};
static struct miscdevice acq_miscdev = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &acq_fops,
};
/*
* Init & exit routines
*/
static int __init acq_probe(struct platform_device *dev)
{
int ret;
if (wdt_stop != wdt_start) {
if (!request_region(wdt_stop, 1, WATCHDOG_NAME)) {
pr_err("I/O address 0x%04x already in use\n", wdt_stop);
ret = -EIO;
goto out;
}
}
if (!request_region(wdt_start, 1, WATCHDOG_NAME)) {
pr_err("I/O address 0x%04x already in use\n", wdt_start);
ret = -EIO;
goto unreg_stop;
}
ret = misc_register(&acq_miscdev);
if (ret != 0) {
pr_err("cannot register miscdev on minor=%d (err=%d)\n",
WATCHDOG_MINOR, ret);
goto unreg_regions;
}
pr_info("initialized. (nowayout=%d)\n", nowayout);
return 0;
unreg_regions:
release_region(wdt_start, 1);
unreg_stop:
if (wdt_stop != wdt_start)
release_region(wdt_stop, 1);
out:
return ret;
}
static void acq_remove(struct platform_device *dev)
{
misc_deregister(&acq_miscdev);
release_region(wdt_start, 1);
if (wdt_stop != wdt_start)
release_region(wdt_stop, 1);
}
static void acq_shutdown(struct platform_device *dev)
{
/* Turn the WDT off if we have a soft shutdown */
acq_stop();
}
static struct platform_driver acquirewdt_driver = {
.remove_new = acq_remove,
.shutdown = acq_shutdown,
.driver = {
.name = DRV_NAME,
},
};
static int __init acq_init(void)
{
int err;
pr_info("WDT driver for Acquire single board computer initialising\n");
acq_platform_device = platform_device_register_simple(DRV_NAME,
-1, NULL, 0);
if (IS_ERR(acq_platform_device))
return PTR_ERR(acq_platform_device);
err = platform_driver_probe(&acquirewdt_driver, acq_probe);
if (err)
goto unreg_platform_device;
return 0;
unreg_platform_device:
platform_device_unregister(acq_platform_device);
return err;
}
static void __exit acq_exit(void)
{
platform_device_unregister(acq_platform_device);
platform_driver_unregister(&acquirewdt_driver);
pr_info("Watchdog Module Unloaded\n");
}
module_init(acq_init);
module_exit(acq_exit);
MODULE_AUTHOR("David Woodhouse");
MODULE_DESCRIPTION("Acquire Inc. Single Board Computer Watchdog Timer driver");
MODULE_LICENSE("GPL");