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|
/*
* Watchdog driver for the mpcore watchdog timer
*
* (c) Copyright 2004 ARM Limited
*
* Based on the SoftDog driver:
* (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
* All Rights Reserved.
*
* 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 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>
*
*/
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/fs.h>
#include <linux/reboot.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
#include <linux/uaccess.h>
#include <asm/hardware/arm_twd.h>
struct mpcore_wdt {
unsigned long timer_alive;
struct device *dev;
void __iomem *base;
int irq;
unsigned int perturb;
char expect_close;
};
static struct platform_device *mpcore_wdt_dev;
extern unsigned int mpcore_timer_rate;
#define TIMER_MARGIN 60
static int mpcore_margin = TIMER_MARGIN;
module_param(mpcore_margin, int, 0);
MODULE_PARM_DESC(mpcore_margin,
"MPcore timer margin in seconds. (0 < mpcore_margin < 65536, default="
__MODULE_STRING(TIMER_MARGIN) ")");
static int nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, int, 0);
MODULE_PARM_DESC(nowayout,
"Watchdog cannot be stopped once started (default="
__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
#define ONLY_TESTING 0
static int mpcore_noboot = ONLY_TESTING;
module_param(mpcore_noboot, int, 0);
MODULE_PARM_DESC(mpcore_noboot, "MPcore watchdog action, set to 1 to ignore reboots, 0 to reboot (default=" __MODULE_STRING(ONLY_TESTING) ")");
/*
* This is the interrupt handler. Note that we only use this
* in testing mode, so don't actually do a reboot here.
*/
static irqreturn_t mpcore_wdt_fire(int irq, void *arg)
{
struct mpcore_wdt *wdt = arg;
/* Check it really was our interrupt */
if (readl(wdt->base + TWD_WDOG_INTSTAT)) {
dev_printk(KERN_CRIT, wdt->dev,
"Triggered - Reboot ignored.\n");
/* Clear the interrupt on the watchdog */
writel(1, wdt->base + TWD_WDOG_INTSTAT);
return IRQ_HANDLED;
}
return IRQ_NONE;
}
/*
* mpcore_wdt_keepalive - reload the timer
*
* Note that the spec says a DIFFERENT value must be written to the reload
* register each time. The "perturb" variable deals with this by adding 1
* to the count every other time the function is called.
*/
static void mpcore_wdt_keepalive(struct mpcore_wdt *wdt)
{
unsigned int count;
/* Assume prescale is set to 256 */
count = (mpcore_timer_rate / 256) * mpcore_margin;
/* Reload the counter */
spin_lock(&wdt_lock);
writel(count + wdt->perturb, wdt->base + TWD_WDOG_LOAD);
wdt->perturb = wdt->perturb ? 0 : 1;
spin_unlock(&wdt_lock);
}
static void mpcore_wdt_stop(struct mpcore_wdt *wdt)
{
spin_lock(&wdt_lock);
writel(0x12345678, wdt->base + TWD_WDOG_DISABLE);
writel(0x87654321, wdt->base + TWD_WDOG_DISABLE);
writel(0x0, wdt->base + TWD_WDOG_CONTROL);
spin_unlock(&wdt_lock);
}
static void mpcore_wdt_start(struct mpcore_wdt *wdt)
{
dev_printk(KERN_INFO, wdt->dev, "enabling watchdog.\n");
spin_lock(&wdt_lock);
/* This loads the count register but does NOT start the count yet */
mpcore_wdt_keepalive(wdt);
if (mpcore_noboot) {
/* Enable watchdog - prescale=256, watchdog mode=0, enable=1 */
writel(0x0000FF01, wdt->base + TWD_WDOG_CONTROL);
} else {
/* Enable watchdog - prescale=256, watchdog mode=1, enable=1 */
writel(0x0000FF09, wdt->base + TWD_WDOG_CONTROL);
}
spin_unlock(&wdt_lock);
}
static int mpcore_wdt_set_heartbeat(int t)
{
if (t < 0x0001 || t > 0xFFFF)
return -EINVAL;
mpcore_margin = t;
return 0;
}
/*
* /dev/watchdog handling
*/
static int mpcore_wdt_open(struct inode *inode, struct file *file)
{
struct mpcore_wdt *wdt = platform_get_drvdata(mpcore_wdt_dev);
if (test_and_set_bit(0, &wdt->timer_alive))
return -EBUSY;
if (nowayout)
__module_get(THIS_MODULE);
file->private_data = wdt;
/*
* Activate timer
*/
mpcore_wdt_start(wdt);
return nonseekable_open(inode, file);
}
static int mpcore_wdt_release(struct inode *inode, struct file *file)
{
struct mpcore_wdt *wdt = file->private_data;
/*
* Shut off the timer.
* Lock it in if it's a module and we set nowayout
*/
if (wdt->expect_close == 42)
mpcore_wdt_stop(wdt);
else {
dev_printk(KERN_CRIT, wdt->dev,
"unexpected close, not stopping watchdog!\n");
mpcore_wdt_keepalive(wdt);
}
clear_bit(0, &wdt->timer_alive);
wdt->expect_close = 0;
return 0;
}
static ssize_t mpcore_wdt_write(struct file *file, const char *data,
size_t len, loff_t *ppos)
{
struct mpcore_wdt *wdt = file->private_data;
/*
* Refresh the timer.
*/
if (len) {
if (!nowayout) {
size_t i;
/* In case it was set long ago */
wdt->expect_close = 0;
for (i = 0; i != len; i++) {
char c;
if (get_user(c, data + i))
return -EFAULT;
if (c == 'V')
wdt->expect_close = 42;
}
}
mpcore_wdt_keepalive(wdt);
}
return len;
}
static struct watchdog_info ident = {
.options = WDIOF_SETTIMEOUT |
WDIOF_KEEPALIVEPING |
WDIOF_MAGICCLOSE,
.identity = "MPcore Watchdog",
};
static long mpcore_wdt_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
struct mpcore_wdt *wdt = file->private_data;
int ret;
union {
struct watchdog_info ident;
int i;
} uarg;
if (_IOC_DIR(cmd) && _IOC_SIZE(cmd) > sizeof(uarg))
return -ENOTTY;
if (_IOC_DIR(cmd) & _IOC_WRITE) {
ret = copy_from_user(&uarg, (void __user *)arg, _IOC_SIZE(cmd));
if (ret)
return -EFAULT;
}
switch (cmd) {
case WDIOC_GETSUPPORT:
uarg.ident = ident;
ret = 0;
break;
case WDIOC_GETSTATUS:
case WDIOC_GETBOOTSTATUS:
uarg.i = 0;
ret = 0;
break;
case WDIOC_SETOPTIONS:
ret = -EINVAL;
if (uarg.i & WDIOS_DISABLECARD) {
mpcore_wdt_stop(wdt);
ret = 0;
}
if (uarg.i & WDIOS_ENABLECARD) {
mpcore_wdt_start(wdt);
ret = 0;
}
break;
case WDIOC_KEEPALIVE:
mpcore_wdt_keepalive(wdt);
ret = 0;
break;
case WDIOC_SETTIMEOUT:
ret = mpcore_wdt_set_heartbeat(uarg.i);
if (ret)
break;
mpcore_wdt_keepalive(wdt);
/* Fall */
case WDIOC_GETTIMEOUT:
uarg.i = mpcore_margin;
ret = 0;
break;
default:
return -ENOTTY;
}
if (ret == 0 && _IOC_DIR(cmd) & _IOC_READ) {
ret = copy_to_user((void __user *)arg, &uarg, _IOC_SIZE(cmd));
if (ret)
ret = -EFAULT;
}
return ret;
}
/*
* System shutdown handler. Turn off the watchdog if we're
* restarting or halting the system.
*/
|