/*
* Watchdog driver for Atmel AT91RM9200 (Thunder)
*
* Copyright (C) 2003 SAN People (Pty) Ltd
*
* 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.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/bitops.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/io.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/uaccess.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <mach/at91_st.h>
#define WDT_DEFAULT_TIME 5 /* seconds */
#define WDT_MAX_TIME 256 /* seconds */
static int wdt_time = WDT_DEFAULT_TIME;
static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(wdt_time, int, 0);
MODULE_PARM_DESC(wdt_time, "Watchdog time in seconds. (default="
__MODULE_STRING(WDT_DEFAULT_TIME) ")");
#ifdef CONFIG_WATCHDOG_NOWAYOUT
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout,
"Watchdog cannot be stopped once started (default="
__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
#endif
static unsigned long at91wdt_busy;
/* ......................................................................... */
/*
* Disable the watchdog.
*/
static inline void at91_wdt_stop(void)
{
at91_st_write(AT91_ST_WDMR, AT91_ST_EXTEN);
}
/*
* Enable and reset the watchdog.
*/
static inline void at91_wdt_start(void)
{
at91_st_write(AT91_ST_WDMR, AT91_ST_EXTEN | AT91_ST_RSTEN |
(((65536 * wdt_time) >> 8) & AT91_ST_WDV));
at91_st_write(AT91_ST_CR, AT91_ST_WDRST);
}
/*
* Reload the watchdog timer. (ie, pat the watchdog)
*/
static inline void at91_wdt_reload(void)
{
at91_st_write(AT91_ST_CR, AT91_ST_WDRST);
}
/* ......................................................................... */
/*
* 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_busy))
return -EBUSY;
at91_wdt_start();
return nonseekable_open(inode, file);
}
/*
* Close the watchdog device.
* If CONFIG_WATCHDOG_NOWAYOUT is NOT defined then the watchdog is also
* disabled.
*/
static int at91_wdt_close(struct inode *inode, struct file *file)
{
/* Disable the watchdog when file is closed */
if (!nowayout)
at91_wdt_stop();
clear_bit(0, &at91wdt_busy);
return 0;
}
/*
* Change the watchdog time interval.
*/
static int at91_wdt_settimeout(int new_time)
{
/*
* All counting occurs at SLOW_CLOCK / 128 = 256 Hz
*
* Since WDV is a 16-bit counter, the maximum period is
* 65536 / 256 = 256 seconds.
*/
if ((new_time <= 0) || (new_time > WDT_MAX_TIME))
return -EINVAL;
/* Set new watchdog time. It will be used when
at91_wdt_start() is called. */
wdt_time = new_time;
return 0;
}
static const struct watchdog_info at91_wdt_info = {
.identity = "at91 watchdog",
.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_SETOPTIONS:
if (get_user(new_value, p))
return -EFAULT;
if (new_value & WDIOS_DISABLECARD)
at91_wdt_stop();
if (new_value & WDIOS_ENABLECARD)
at91_wdt_start();
return 0;
case WDIOC_KEEPALIVE:
at91_wdt_reload(); /* pat the watchdog */
return 0;
case WDIOC_SETTIMEOUT:
if (get_user(new_value, p))
return -EFAULT;
if (at91_wdt_settimeout(new_value))
return -EINVAL;
/* Enable new time value */
at91_wdt_start();
/* Return current value */
return put_user(wdt_time, p);
case WDIOC_GETTIMEOUT:
return put_user(wdt_time, p);
default:
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)
{
at91_wdt_reload(); /* pat the watchdog */
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 at91wdt_probe(struct platform_device *pdev)
{
int res;
if (at91wdt_miscdev.parent)
return -EBUSY;
at91wdt_miscdev.parent = &pdev->dev;
res = misc_register(&at91wdt_miscdev);
if (res)
return res;
pr_info("AT91 Watchdog Timer enabled (%d seconds%s)\n",
wdt_time, nowayout ? ", nowayout" : "");
return 0;
}
static int at91wdt_remove(struct platform_device *pdev)
{
int res;
res = misc_deregister(&at91wdt_miscdev);
if (!res)
at91wdt_miscdev.parent = NULL;
return res;
}
static void at91wdt_shutdown(struct platform_device *pdev)
{
at91_wdt_stop();
}
#ifdef CONFIG_PM
static int at91wdt_suspend(struct platform_device *pdev, pm_message_t message)
{
at91_wdt_stop();
return 0;
}
static int at91wdt_resume(struct platform_device *pdev)
{
if (at91wdt_busy)
at91_wdt_start();
return 0;
}
#else
#define at91wdt_suspend NULL
#define at91wdt_resume NULL
#endif
static const struct of_device_id at91_wdt_dt_ids[] = {
{ .compatible = "atmel,at91rm9200-wdt" },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, at91_wdt_dt_ids);
static struct platform_driver at91wdt_driver = {
.probe = at91wdt_probe,
.remove = at91wdt_remove,
.shutdown = at91wdt_shutdown,
.suspend = at91wdt_suspend,
.resume = at91wdt_resume,
.driver = {
.name = "at91_wdt",
.of_match_table = at91_wdt_dt_ids,
},
};
static int __init at91_wdt_init(void)
{
/* Check that the heartbeat value is within range;
if not reset to the default */
if (at91_wdt_settimeout(wdt_time)) {
at91_wdt_settimeout(WDT_DEFAULT_TIME);
pr_info("wdt_time value must be 1 <= wdt_time <= 256, using %d\n",
wdt_time);
}
return platform_driver_register(&at91wdt_driver);
}
static void __exit at91_wdt_exit(void)
{
platform_driver_unregister(&at91wdt_driver);
}
module_init(at91_wdt_init);
module_exit(at91_wdt_exit);
MODULE_AUTHOR("Andrew Victor");
MODULE_DESCRIPTION("Watchdog driver for Atmel AT91RM9200");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:at91_wdt");
