ixp4xx_wdt.c
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/*
* drivers/char/watchdog/ixp4xx_wdt.c
*
* Watchdog driver for Intel IXP4xx network processors
*
* Author: Deepak Saxena <dsaxena@plexity.net>
*
* Copyright 2004 (c) MontaVista, Software, Inc.
* Based on sa1100 driver, Copyright (C) 2000 Oleg Drokin <green@crimea.edu>
*
* This file is licensed under the terms of the GNU General Public
* License version 2. This program is licensed "as is" without any
* warranty of any kind, whether express or implied.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/init.h>
#include <linux/bitops.h>
#include <linux/uaccess.h>
#include <mach/hardware.h>
static bool nowayout = WATCHDOG_NOWAYOUT;
static int heartbeat = 60; /* (secs) Default is 1 minute */
static unsigned long wdt_status;
static unsigned long boot_status;
static DEFINE_SPINLOCK(wdt_lock);
#define WDT_TICK_RATE (IXP4XX_PERIPHERAL_BUS_CLOCK * 1000000UL)
#define WDT_IN_USE 0
#define WDT_OK_TO_CLOSE 1
static void wdt_enable(void)
{
spin_lock(&wdt_lock);
*IXP4XX_OSWK = IXP4XX_WDT_KEY;
*IXP4XX_OSWE = 0;
*IXP4XX_OSWT = WDT_TICK_RATE * heartbeat;
*IXP4XX_OSWE = IXP4XX_WDT_COUNT_ENABLE | IXP4XX_WDT_RESET_ENABLE;
*IXP4XX_OSWK = 0;
spin_unlock(&wdt_lock);
}
static void wdt_disable(void)
{
spin_lock(&wdt_lock);
*IXP4XX_OSWK = IXP4XX_WDT_KEY;
*IXP4XX_OSWE = 0;
*IXP4XX_OSWK = 0;
spin_unlock(&wdt_lock);
}
static int ixp4xx_wdt_open(struct inode *inode, struct file *file)
{
if (test_and_set_bit(WDT_IN_USE, &wdt_status))
return -EBUSY;
clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
wdt_enable();
return nonseekable_open(inode, file);
}
static ssize_t
ixp4xx_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos)
{
if (len) {
if (!nowayout) {
size_t i;
clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
for (i = 0; i != len; i++) {
char c;
if (get_user(c, data + i))
return -EFAULT;
if (c == 'V')
set_bit(WDT_OK_TO_CLOSE, &wdt_status);
}
}
wdt_enable();
}
return len;
}
static const struct watchdog_info ident = {
.options = WDIOF_CARDRESET | WDIOF_MAGICCLOSE |
WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
.identity = "IXP4xx Watchdog",
};
static long ixp4xx_wdt_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
int ret = -ENOTTY;
int time;
switch (cmd) {
case WDIOC_GETSUPPORT:
ret = copy_to_user((struct watchdog_info *)arg, &ident,
sizeof(ident)) ? -EFAULT : 0;
break;
case WDIOC_GETSTATUS:
ret = put_user(0, (int *)arg);
break;
case WDIOC_GETBOOTSTATUS:
ret = put_user(boot_status, (int *)arg);
break;
case WDIOC_KEEPALIVE:
wdt_enable();
ret = 0;
break;
case WDIOC_SETTIMEOUT:
ret = get_user(time, (int *)arg);
if (ret)
break;
if (time <= 0 || time > 60) {
ret = -EINVAL;
break;
}
heartbeat = time;
wdt_enable();
/* Fall through */
case WDIOC_GETTIMEOUT:
ret = put_user(heartbeat, (int *)arg);
break;
}
return ret;
}
static int ixp4xx_wdt_release(struct inode *inode, struct file *file)
{
if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
wdt_disable();
else
pr_crit("Device closed unexpectedly - timer will not stop\n");
clear_bit(WDT_IN_USE, &wdt_status);
clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
return 0;
}
static const struct file_operations ixp4xx_wdt_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
.write = ixp4xx_wdt_write,
.unlocked_ioctl = ixp4xx_wdt_ioctl,
.open = ixp4xx_wdt_open,
.release = ixp4xx_wdt_release,
};
static struct miscdevice ixp4xx_wdt_miscdev = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &ixp4xx_wdt_fops,
};
static int __init ixp4xx_wdt_init(void)
{
int ret;
if (!(read_cpuid_id() & 0xf) && !cpu_is_ixp46x()) {
pr_err("Rev. A0 IXP42x CPU detected - watchdog disabled\n");
return -ENODEV;
}
boot_status = (*IXP4XX_OSST & IXP4XX_OSST_TIMER_WARM_RESET) ?
WDIOF_CARDRESET : 0;
ret = misc_register(&ixp4xx_wdt_miscdev);
if (ret == 0)
pr_info("timer heartbeat %d sec\n", heartbeat);
return ret;
}
static void __exit ixp4xx_wdt_exit(void)
{
misc_deregister(&ixp4xx_wdt_miscdev);
}
module_init(ixp4xx_wdt_init);
module_exit(ixp4xx_wdt_exit);
MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net>");
MODULE_DESCRIPTION("IXP4xx Network Processor Watchdog");
module_param(heartbeat, int, 0);
MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds (default 60s)");
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
MODULE_LICENSE("GPL");