/*
* Watchdog driver for Cirrus Logic EP93xx family of devices.
*
* Copyright (c) 2004 Ray Lehtiniemi
* Copyright (c) 2006 Tower Technologies
* Based on ep93xx driver, bits from alim7101_wdt.c
*
* Authors: Ray Lehtiniemi <rayl@mail.com>,
* Alessandro Zummo <a.zummo@towertech.it>
*
* 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.
*
* This watchdog fires after 250msec, which is a too short interval
* for us to rely on the user space daemon alone. So we ping the
* wdt each ~200msec and eventually stop doing it if the user space
* daemon dies.
*
* TODO:
*
* - Test last reset from watchdog status
* - Add a few missing ioctls
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/platform_device.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/timer.h>
#include <linux/uaccess.h>
#include <linux/io.h>
#define WDT_VERSION "0.3"
/* default timeout (secs) */
#define WDT_TIMEOUT 30
static bool nowayout = WATCHDOG_NOWAYOUT;
static int timeout = WDT_TIMEOUT;
static void __iomem *mmio_base;
static struct timer_list timer;
static unsigned long next_heartbeat;
static unsigned long wdt_status;
static unsigned long boot_status;
#define WDT_IN_USE 0
#define WDT_OK_TO_CLOSE 1
#define EP93XX_WATCHDOG 0x00
#define EP93XX_WDSTATUS 0x04
/* reset the wdt every ~200ms */
#define WDT_INTERVAL (HZ/5)
static void wdt_enable(void)
{
writel(0xaaaa, mmio_base + EP93XX_WATCHDOG);
}
static void wdt_disable(void)
{
writel(0xaa55, mmio_base + EP93XX_WATCHDOG);
}
static inline void wdt_ping(void)
{
writel(0x5555, mmio_base + EP93XX_WATCHDOG);
}
static void wdt_startup(void)
{
next_heartbeat = jiffies + (timeout * HZ);
wdt_enable();
mod_timer(&timer, jiffies + WDT_INTERVAL);
}
static void wdt_shutdown(void)
{
del_timer_sync(&timer);
wdt_disable();
}
static void wdt_keepalive(void)
{
/* user land ping */
next_heartbeat = jiffies + (timeout * HZ);
}
static int ep93xx_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_startup();
return nonseekable_open(inode, file);
}
static ssize_t
ep93xx_wdt_write(struct file *file, const char __user *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);
else
clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
}
}
wdt_keepalive();
}
return len;
}
static const struct watchdog_info ident = {
.options = WDIOF_CARDRESET | WDIOF_MAGICCLOSE,
.identity = "EP93xx Watchdog",
};
static long ep93xx_wdt_ioctl(struct file *file,
unsigned int cmd, unsigned long arg)
{
int ret = -ENOTTY;
switch (cmd) {
case WDIOC_GETSUPPORT:
ret = copy_to_user((struct watchdog_info __user *)arg, &ident,
sizeof(ident)) ? -EFAULT : 0;
break;
case WDIOC_GETSTATUS:
ret = put_user(0, (int __user *)arg);
break;
case WDIOC_GETBOOTSTATUS:
ret = put_user(boot_status, (int __user *)arg);
break;
case WDIOC_KEEPALIVE:
wdt_keepalive();
ret = 0;
break;
case WDIOC_GETTIMEOUT:
/* actually, it is 0.250 seconds.... */
ret = put_user(1, (int __user *)arg);
break;
}
return ret;
}
static int ep93xx_wdt_release(struct inode *inode, struct file *file)
{
if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
wdt_shutdown();
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 ep93xx_wdt_fops = {
.owner = THIS_MODULE,
.write = ep93xx_wdt_write,
.unlocked_ioctl = ep93xx_wdt_ioctl,
.open = ep93xx_wdt_open,
.release = ep93xx_wdt_release,
.llseek = no_llseek,
};
static struct miscdevice ep93xx_wdt_miscdev = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &ep93xx_wdt_fops,
};
static void ep93xx_timer_ping(unsigned long data)
{
if (time_before(jiffies, next_heartbeat))
wdt_ping();
/* Re-set the timer interval */
mod_timer(&timer, jiffies + WDT_INTERVAL);
}
static int __devinit ep93xx_wdt_probe(struct platform_device *pdev)
{
struct resource *res;
unsigned long val;
int err;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!res)
return -ENXIO;
if (!devm_request_mem_region(&pdev->dev, res->start,
resource_size(res), pdev->name))
return -EBUSY;
mmio_base = devm_ioremap(&pdev->dev, res->start, resource_size(res));
if (!mmio_base)
return -ENXIO;
if (timeout < 1 || timeout > 3600) {
timeout = WDT_TIMEOUT;
pr_info("timeout value must be 1<=x<=3600, using %d\n",
timeout);
}
val = readl(mmio_base + EP93XX_WATCHDOG);
boot_status = val & 0x01 ? 1 : 0;
setup_timer(&timer, ep93xx_timer_ping, 1);
err = misc_register(&ep93xx_wdt_miscdev);
pr_info("EP93XX watchdog, driver version " WDT_VERSION "%s\n",
(val & 0x08) ? " (nCS1 disable detected)" : "");
return err;
}
static int __devexit ep93xx_wdt_remove(struct platform_device *pdev)
{
wdt_shutdown();
misc_deregister(&ep93xx_wdt_miscdev);
return 0;
}
static struct platform_driver ep93xx_wdt_driver = {
.driver = {
.owner = THIS_MODULE,
.name = "ep93xx-wdt",
},
.probe = ep93xx_wdt_probe,
.remove = __devexit_p(ep93xx_wdt_remove),
};
module_platform_driver(ep93xx_wdt_driver);
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
module_param(timeout, int, 0);
MODULE_PARM_DESC(timeout,
"Watchdog timeout in seconds. (1<=timeout<=3600, default="
__MODULE_STRING(WDT_TIMEOUT) ")");
MODULE_AUTHOR("Ray Lehtiniemi <rayl@mail.com>,"
"Alessandro Zummo <a.zummo@towertech.it>");
MODULE_DESCRIPTION("EP93xx Watchdog");
MODULE_LICENSE("GPL");
MODULE_VERSION(WDT_VERSION);
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
