/*
* Watchdog driver for Atmel AT91SAM9x processors.
*
* Copyright (C) 2008 Renaud CERRATO r.cerrato@til-technologies.fr
*
* 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.
*/
/*
* The Watchdog Timer Mode Register can be only written to once. If the
* timeout need to be set from Linux, be sure that the bootstrap or the
* bootloader doesn't write to this register.
*/
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/platform_device.h>
#include <linux/types.h>
#include <linux/watchdog.h>
#include <linux/jiffies.h>
#include <linux/timer.h>
#include <linux/bitops.h>
#include <linux/uaccess.h>
#include <asm/arch/at91_wdt.h>
#define DRV_NAME "AT91SAM9 Watchdog"
/* AT91SAM9 watchdog runs a 12bit counter @ 256Hz,
* use this to convert a watchdog
* value from/to milliseconds.
*/
#define ms_to_ticks(t) (((t << 8) / 1000) - 1)
#define ticks_to_ms(t) (((t + 1) * 1000) >> 8)
/* Hardware timeout in seconds */
#define WDT_HW_TIMEOUT 2
/* Timer heartbeat (500ms) */
#define WDT_TIMEOUT (HZ/2)
/* User land timeout */
#define WDT_HEARTBEAT 15
static int heartbeat = WDT_HEARTBEAT;
module_param(heartbeat, int, 0);
MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. "
"(default = " __MODULE_STRING(WDT_HEARTBEAT) ")");
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) ")");
static void at91_ping(unsigned long data);
static struct {
unsigned long next_heartbeat; /* the next_heartbeat for the timer */
unsigned long open;
char expect_close;
struct timer_list timer; /* The timer that pings the watchdog */
} at91wdt_private;
/* ......................................................................... */
/*
* Reload the watchdog timer. (ie, pat the watchdog)
*/
static inline void at91_wdt_reset(void)
{
at91_sys_write(AT91_WDT_CR, AT91_WDT_KEY | AT91_WDT_WDRSTT);
}
/*
* Timer tick
*/
static void at91_ping(unsigned long data)
{
if (time_before(jiffies, at91wdt_private.next_heartbeat) ||
(!nowayout && !at91wdt_private.open)) {
at91_wdt_reset();
mod_timer(&at91wdt_private.timer, jiffies + WDT_TIMEOUT);
} else
printk(KERN_CRIT DRV_NAME": I will reset your machine !\n");
}
/*
* Watchdog device is opened, and watchdog starts running.
*/
static int at91_wdt_open(struct inode *inode, struct file *file)
{
if (test_and_set_bit(0, &at91wdt_private.open))
return -EBUSY;
at91wdt_private.next_heartbeat = jiffies + heartbeat * HZ;
mod_timer(&at91wdt_private.timer, jiffies + WDT_TIMEOUT);
return nonseekable_open(inode, file);
}
/*
* Close the watchdog device.
*/
static int at91_wdt_close(struct inode *inode, struct file *file)
{
clear_bit(0, &at91wdt_private.open);
/* stop internal ping */
if (!at91wdt_private.expect_close)
del_timer(&at91wdt_private.timer);
at91wdt_private.expect_close = 0;
return 0;
}
/*
* Set the watchdog time interval in 1/256Hz (write-once)
* Counter is 12 bit.
*/
static int at91_wdt_settimeout(unsigned int timeout)
{
unsigned int reg;
unsigned int mr;
/* Check if disabled */
mr = at91_sys_read(AT91_WDT_MR);
if (mr & AT91_WDT_WDDIS) {
printk(KERN_ERR DRV_NAME": sorry, watchdog is disabled\n");
return -EIO;
}
/*
* All counting occurs at SLOW_CLOCK / 128 = 256 Hz
*
* Since WDV is a 12-bit counter, the maximum period is
* 4096 / 256 = 16 seconds.
*/
reg = AT91_WDT_WDRSTEN /* causes watchdog reset */
/* | AT91_WDT_WDRPROC causes processor reset only */
| AT91_WDT_WDDBGHLT /* disabled in debug mode */
| AT91_WDT_WDD /* restart at any time */
| (timeout & AT91_WDT_WDV); /* timer value */
at91_sys_write(AT91_WDT_MR, reg);
return 0;
}
static const struct watchdog_info at91_wdt_info = {
.identity = DRV_NAME,
.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
};
/*
* Handle commands from user-space.
*/
static long at91_wdt_ioctl(struct file *file,
unsigned int cmd, unsigned long arg)
{
void __user *argp = (void __user *)arg;
int __user *p = argp;
int new_value;
switch (cmd) {
case WDIOC_GETSUPPORT:
return copy_to_user(argp, &at91_wdt_info,
sizeof(at91_wdt_info)) ? -EFAULT : 0;
case WDIOC_GETSTATUS:
case WDIOC_GETBOOTSTATUS:
return put_user(0, p);
case WDIOC_KEEPALIVE:
at91wdt_private.next_heartbeat = jiffies + heartbeat * HZ;
return 0;
case WDIOC_SETTIMEOUT:
if (get_user(new_value, p))
return -EFAULT;
heartbeat = new_value;
at91wdt_private.next_heartbeat = jiffies + heartbeat * HZ;
return put_user(new_value, p); /* return current value */
case WDIOC_GETTIMEOUT:
return put_user(heartbeat, p);
}
return -ENOTTY;
}
/*
* Pat the watchdog whenever device is written to.
*/
static ssize_t at91_wdt_write(struct file *file, const char *data, size_t len,
loff_t *ppos)
{
if (!len)
return 0;
/* Scan for magic character */
if (!nowayout) {
size_t i;
at91wdt_private.expect_close = 0;
for (i = 0; i < len; i++) {
char c;
if (get_user(c, data + i))
return -EFAULT;
if (c == 'V') {
at91wdt_private.expect_close = 42;
break;
}
}
}
at91wdt_private.next_heartbeat = jiffies + heartbeat * HZ;
return len;
}
/* ......................................................................... */
static const struct file_operations at91wdt_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
.unlocked_ioctl = at91_wdt_ioctl,
.open = at91_wdt_open,
.release = at91_wdt_close,
.write = at91_wdt_write,
};
static struct miscdevice at91wdt_miscdev = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &at91wdt_fops,
};
static int __init at91wdt_probe(struct platform_device *pdev)
{
int res;
if (at91wdt_miscdev.parent)
return -EBUSY;
at91wdt_miscdev.parent = &pdev->dev;
/* Set watchdog */
res = at91_wdt_settimeout(ms_to_ticks(WDT_HW_TIMEOUT * 1000));
if (res)
return res;
res = misc_register(&at91wdt_miscdev);
if (res)
return res;
at91wdt_private.next_heartbeat = jiffies + heartbeat * HZ;
setup_timer(&at91wdt_private.timer, at91_ping, 0);
mod_timer(&at91wdt_private.timer, jiffies + WDT_TIMEOUT);
printk(KERN_INFO DRV_NAME " enabled (heartbeat=%d sec, nowayout=%d)\n",
heartbeat, nowayout);
return 0;
}
static int __exit at91wdt_remove(struct platform_device *pdev)
{
int res;
res = misc_deregister(&at91wdt_miscdev);
if (!res)
at91wdt_miscdev.parent = NULL;
return res;
}
#ifdef CONFIG_PM
static int at91wdt_suspend(struct platform_device *pdev, pm_message_t message)
{
return 0;
}
static int at91wdt_resume(struct platform_device *pdev)
{
return 0;
}
#else
#define at91wdt_suspend NULL
#define at91wdt_resume NULL
#endif
static struct platform_driver at91wdt_driver = {
.remove = __exit_p(at91wdt_remove),
.suspend = at91wdt_suspend,
.resume = at91wdt_resume,
.driver = {
.name = "at91_wdt",
.owner = THIS_MODULE,
},
};
static int __init at91sam_wdt_init(void)
{
return platform_driver_probe(&at91wdt_driver, at91wdt_probe);
}
static void __exit at91sam_wdt_exit(void)
{
platform_driver_unregister(&at91wdt_driver);
}
module_init(at91sam_wdt_init);
module_exit(at91sam_wdt_exit);
MODULE_AUTHOR("Renaud CERRATO <r.cerrato@til-technologies.fr>");
MODULE_DESCRIPTION("Watchdog driver for Atmel AT91SAM9x processors");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
