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openwrt/target/linux/ar7-2.6/files/drivers/char/watchdog/ar7_wdt.c

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/*
* linux/drivers/char/ar7_wdt.c
*
* Copyright (C) 2007 OpenWrt.org
* Copyright (c) 2005 Enrik Berkhan <Enrik.Berkhan@akk.org>
*
* Some code taken from:
* National Semiconductor SCx200 Watchdog support
* Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.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.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/notifier.h>
#include <linux/reboot.h>
#include <linux/fs.h>
#include <linux/ioport.h>
#include <asm/addrspace.h>
#include <asm/io.h>
#include <asm/uaccess.h>
#include <asm/ar7/ar7.h>
#define DRVNAME "ar7_wdt"
#define LONGNAME "TI AR7 Watchdog Timer"
MODULE_AUTHOR("Nicolas Thill <nico@openwrt.org>");
MODULE_DESCRIPTION(LONGNAME);
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
static int margin = 60;
module_param(margin, int, 0);
MODULE_PARM_DESC(margin, "Watchdog margin in seconds");
static int nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, int, 0);
MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
typedef struct {
u32 kick_lock;
u32 kick;
u32 change_lock;
u32 change ;
u32 disable_lock;
u32 disable;
u32 prescale_lock;
u32 prescale;
} ar7_wdt_t;
static struct semaphore open_semaphore;
static unsigned expect_close;
/* XXX currently fixed, allows max margin ~68.72 secs */
#define prescale_value 0xFFFF
// Offset of the WDT registers
static unsigned long ar7_regs_wdt;
// Pointer to the remapped WDT IO space
static ar7_wdt_t *ar7_wdt;
static void ar7_wdt_get_regs(void)
{
u16 chip_id = ar7_chip_id();
switch (chip_id)
{
case AR7_CHIP_7100:
case AR7_CHIP_7200:
ar7_regs_wdt = AR7_REGS_WDT;
break;
default:
ar7_regs_wdt = UR8_REGS_WDT;
break;
}
}
static void ar7_wdt_kick(u32 value)
{
ar7_wdt->kick_lock = 0x5555;
if ((ar7_wdt->kick_lock & 3) == 1) {
ar7_wdt->kick_lock = 0xAAAA;
if ((ar7_wdt->kick_lock & 3) == 3) {
ar7_wdt->kick = value;
return;
}
}
printk(KERN_ERR DRVNAME ": failed to unlock WDT kick reg\n");
}
static void ar7_wdt_prescale(u32 value)
{
ar7_wdt->prescale_lock = 0x5A5A;
if ((ar7_wdt->prescale_lock & 3) == 1) {
ar7_wdt->prescale_lock = 0xA5A5;
if ((ar7_wdt->prescale_lock & 3) == 3) {
ar7_wdt->prescale = value;
return;
}
}
printk(KERN_ERR DRVNAME ": failed to unlock WDT prescale reg\n");
}
static void ar7_wdt_change(u32 value)
{
ar7_wdt->change_lock = 0x6666;
if ((ar7_wdt->change_lock & 3) == 1) {
ar7_wdt->change_lock = 0xBBBB;
if ((ar7_wdt->change_lock & 3) == 3) {
ar7_wdt->change = value;
return;
}
}
printk(KERN_ERR DRVNAME ": failed to unlock WDT change reg\n");
}
static void ar7_wdt_disable(u32 value)
{
ar7_wdt->disable_lock = 0x7777;
if ((ar7_wdt->disable_lock & 3) == 1) {
ar7_wdt->disable_lock = 0xCCCC;
if ((ar7_wdt->disable_lock & 3) == 2) {
ar7_wdt->disable_lock = 0xDDDD;
if ((ar7_wdt->disable_lock & 3) == 3) {
ar7_wdt->disable = value;
return;
}
}
}
printk(KERN_ERR DRVNAME ": failed to unlock WDT disable reg\n");
}
static void ar7_wdt_update_margin(int new_margin)
{
u32 change;
change = new_margin * (ar7_vbus_freq() / prescale_value);
if (change < 1) change = 1;
if (change > 0xFFFF) change = 0xFFFF;
ar7_wdt_change(change);
margin = change * prescale_value / ar7_vbus_freq();
printk(KERN_INFO DRVNAME
": timer margin %d seconds (prescale %d, change %d, freq %d)\n",
margin, prescale_value, change, ar7_vbus_freq());
}
static void ar7_wdt_enable_wdt(void)
{
printk(KERN_DEBUG DRVNAME ": enabling watchdog timer\n");
ar7_wdt_disable(1);
ar7_wdt_kick(1);
}
static void ar7_wdt_disable_wdt(void)
{
printk(KERN_DEBUG DRVNAME ": disabling watchdog timer\n");
ar7_wdt_disable(0);
}
static int ar7_wdt_open(struct inode *inode, struct file *file)
{
/* only allow one at a time */
if (down_trylock(&open_semaphore))
return -EBUSY;
ar7_wdt_enable_wdt();
expect_close = 0;
return 0;
}
static int ar7_wdt_release(struct inode *inode, struct file *file)
{
if (!expect_close) {
printk(KERN_WARNING DRVNAME ": watchdog device closed unexpectedly, will not disable the watchdog timer\n");
} else if (!nowayout) {
ar7_wdt_disable_wdt();
}
up(&open_semaphore);
return 0;
}
static int ar7_wdt_notify_sys(struct notifier_block *this,
unsigned long code, void *unused)
{
if (code == SYS_HALT || code == SYS_POWER_OFF)
if (!nowayout)
ar7_wdt_disable_wdt();
return NOTIFY_DONE;
}
static struct notifier_block ar7_wdt_notifier =
{
.notifier_call = ar7_wdt_notify_sys
};
static ssize_t ar7_wdt_write(struct file *file, const char *data,
size_t len, loff_t *ppos)
{
if (ppos != &file->f_pos)
return -ESPIPE;
/* check for a magic close character */
if (len) {
size_t i;
ar7_wdt_kick(1);
expect_close = 0;
for (i = 0; i < len; ++i) {
char c;
if (get_user(c, data+i))
return -EFAULT;
if (c == 'V')
expect_close = 1;
}
}
return len;
}
static int ar7_wdt_ioctl(struct inode *inode, struct file *file,
unsigned int cmd, unsigned long arg)
{
static struct watchdog_info ident = {
.identity = LONGNAME,
.firmware_version = 1,
.options = (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING),
};
int new_margin;
switch (cmd) {
default:
return -ENOTTY;
case WDIOC_GETSUPPORT:
if(copy_to_user((struct watchdog_info *)arg, &ident,
sizeof(ident)))
return -EFAULT;
return 0;
case WDIOC_GETSTATUS:
case WDIOC_GETBOOTSTATUS:
if (put_user(0, (int *)arg))
return -EFAULT;
return 0;
case WDIOC_KEEPALIVE:
ar7_wdt_kick(1);
return 0;
case WDIOC_SETTIMEOUT:
if (get_user(new_margin, (int *)arg))
return -EFAULT;
if (new_margin < 1)
return -EINVAL;
ar7_wdt_update_margin(new_margin);
ar7_wdt_kick(1);
case WDIOC_GETTIMEOUT:
if (put_user(margin, (int *)arg))
return -EFAULT;
return 0;
}
}
static struct file_operations ar7_wdt_fops = {
.owner = THIS_MODULE,
.write = ar7_wdt_write,
.ioctl = ar7_wdt_ioctl,
.open = ar7_wdt_open,
.release = ar7_wdt_release,
};
static struct miscdevice ar7_wdt_miscdev = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &ar7_wdt_fops,
};
static int __init ar7_wdt_init(void)
{
int rc;
ar7_wdt_get_regs();
if (!request_mem_region(ar7_regs_wdt, sizeof(ar7_wdt_t), LONGNAME)) {
printk(KERN_WARNING DRVNAME ": watchdog I/O region busy\n");
return -EBUSY;
}
ar7_wdt = (ar7_wdt_t *)ioremap(ar7_regs_wdt, sizeof(ar7_wdt_t));
ar7_wdt_disable_wdt();
ar7_wdt_prescale(prescale_value);
ar7_wdt_update_margin(margin);
sema_init(&open_semaphore, 1);
rc = misc_register(&ar7_wdt_miscdev);
if (rc) {
printk(KERN_ERR DRVNAME ": unable to register misc device\n");
goto out_alloc;
}
rc = register_reboot_notifier(&ar7_wdt_notifier);
if (rc) {
printk(KERN_ERR DRVNAME ": unable to register reboot notifier\n");
goto out_register;
}
goto out;
out_register:
misc_deregister(&ar7_wdt_miscdev);
out_alloc:
release_mem_region(ar7_regs_wdt, sizeof(ar7_wdt_t));
out:
return rc;
}
static void __exit ar7_wdt_cleanup(void)
{
unregister_reboot_notifier(&ar7_wdt_notifier);
misc_deregister(&ar7_wdt_miscdev);
iounmap(ar7_wdt);
release_mem_region(ar7_regs_wdt, sizeof(ar7_wdt_t));
}
module_init(ar7_wdt_init);
module_exit(ar7_wdt_cleanup);
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