/*
* Blackfin On-Chip Watchdog Driver
* Supports BF53[123]/BF53[467]/BF54[2489]/BF561
*
* Originally based on softdog.c
* Copyright 2006-2007 Analog Devices Inc.
* Copyright 2006-2007 Michele d'Amico
* Copyright 1996 Alan Cox <alan@redhat.com>
*
* Enter bugs at http://blackfin.uclinux.org/
*
* Licensed under the GPL-2 or later.
*/
#include <linux/platform_device.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/timer.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/fs.h>
#include <linux/notifier.h>
#include <linux/reboot.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <asm/blackfin.h>
#include <asm/uaccess.h>
#define stamp(fmt, args...) pr_debug("%s:%i: " fmt "\n", __func__, __LINE__, ## args)
#define stampit() stamp("here i am")
#define pr_init(fmt, args...) ({ static const __initdata char __fmt[] = fmt; printk(__fmt, ## args); })
#define WATCHDOG_NAME "bfin-wdt"
#define PFX WATCHDOG_NAME ": "
/* The BF561 has two watchdogs (one per core), but since Linux
* only runs on core A, we'll just work with that one.
*/
#ifdef BF561_FAMILY
# define bfin_read_WDOG_CTL() bfin_read_WDOGA_CTL()
# define bfin_read_WDOG_CNT() bfin_read_WDOGA_CNT()
# define bfin_read_WDOG_STAT() bfin_read_WDOGA_STAT()
# define bfin_write_WDOG_CTL(x) bfin_write_WDOGA_CTL(x)
# define bfin_write_WDOG_CNT(x) bfin_write_WDOGA_CNT(x)
# define bfin_write_WDOG_STAT(x) bfin_write_WDOGA_STAT(x)
#endif
/* Bit in SWRST that indicates boot caused by watchdog */
#define SWRST_RESET_WDOG 0x4000
/* Bit in WDOG_CTL that indicates watchdog has expired (WDR0) */
#define WDOG_EXPIRED 0x8000
/* Masks for WDEV field in WDOG_CTL register */
#define ICTL_RESET 0x0
#define ICTL_NMI 0x2
#define ICTL_GPI 0x4
#define ICTL_NONE 0x6
#define ICTL_MASK 0x6
/* Masks for WDEN field in WDOG_CTL register */
#define WDEN_MASK 0x0FF0
#define WDEN_ENABLE 0x0000
#define WDEN_DISABLE 0x0AD0
/* some defaults */
#define WATCHDOG_TIMEOUT 20
static unsigned int timeout = WATCHDOG_TIMEOUT;
static int nowayout = WATCHDOG_NOWAYOUT;
static struct watchdog_info bfin_wdt_info;
static unsigned long open_check;
static char expect_close;
static DEFINE_SPINLOCK(bfin_wdt_spinlock);
/**
* bfin_wdt_keepalive - Keep the Userspace Watchdog Alive
*
* The Userspace watchdog got a KeepAlive: schedule the next timeout.
*/
static int bfin_wdt_keepalive(void)
{
stampit();
bfin_write_WDOG_STAT(0);
return 0;
}
/**
* bfin_wdt_stop - Stop the Watchdog
*
* Stops the on-chip watchdog.
*/
static int bfin_wdt_stop(void)
{
stampit();
bfin_write_WDOG_CTL(WDEN_DISABLE);
return 0;
}
/**
* bfin_wdt_start - Start the Watchdog
*
* Starts the on-chip watchdog. Automatically loads WDOG_CNT
* into WDOG_STAT for us.
*/
static int bfin_wdt_start(void)
{
stampit();
bfin_write_WDOG_CTL(WDEN_ENABLE | ICTL_RESET);
return 0;
}
/**
* bfin_wdt_running - Check Watchdog status
*
* See if the watchdog is running.
*/
static int bfin_wdt_running(void)
{
stampit();
return ((bfin_read_WDOG_CTL() & WDEN_MASK) != WDEN_DISABLE);
}
/**
* bfin_wdt_set_timeout - Set the Userspace Watchdog timeout
* @t: new timeout value (in seconds)
*
* Translate the specified timeout in seconds into System Clock
* terms which is what the on-chip Watchdog requires.
*/
static int bfin_wdt_set_timeout(unsigned long t)
{
u32 cnt;
unsigned long flags;
stampit();
cnt = t * get_sclk();
if (cnt < get_sclk()) {
printk(KERN_WARNING PFX "timeout value is too large\n");
return -EINVAL;
}
spin_lock_irqsave(&bfin_wdt_spinlock, flags);
{
int run = bfin_wdt_running();
bfin_wdt_stop();
bfin_write_WDOG_CNT(cnt);
if (run) bfin_wdt_start();
}
spin_unlock_irqrestore(&bfin_wdt_spinlock, flags);
timeout = t;
return 0;
}
/**
* bfin_wdt_open - Open the Device
* @inode: inode of device
* @file: file handle of device
*
* Watchdog device is opened and started.
*/
static int bfin_wdt_open(struct inode *inode, struct file *file)
{
stampit();
if (test_and_set_bit(0, &open_check))
return -EBUSY;
if (nowayout)
__module_get(THIS_MODULE);
bfin_wdt_keepalive();
bfin_wdt_start();
return nonseekable_open(inode, file);
}
/**
* bfin_wdt_close - Close the Device
* @inode: inode of device
* @file: file handle of device
*
* Watchdog device is closed and stopped.
*/
static int bfin_wdt_release(struct inode *inode, struct file *file)
{
stampit();
if (expect_close == 42) {
bfin_wdt_stop();
} else {
printk(KERN_CRIT PFX "Unexpected close, not stopping watchdog!\n");
bfin_wdt_keepalive();
}
expect_close = 0;
clear_bit(0, &open_check);
return 0;
}
/**
* bfin_wdt_write - Write to Device
* @file: file handle of device
* @buf: buffer to write
* @count: length of buffer
* @ppos: offset
*
* Pings the watchdog on write.
*/
static ssize_t bfin_wdt_write(struct file *file, const char __user *data,
size_t len, loff_t *ppos)
{
stampit();
if (len) {
if (!nowayout) {
size_t i;
/* In case it was set long ago */
expect_close = 0;
for (i = 0; i != len; i++) {
char c;
if (get_user(c, data + i))
return -EFAULT;
if (c == 'V')
expect_close = 42;
}
}
bfin_wdt_keepalive();
}
return len;
}
/**
* bfin_wdt_ioctl - Query Device
* @inode: inode of device
* @file: file handle of device
* @cmd: watchdog command
* @arg: argument
*
* Query basic information from the device or ping it, as outlined by the
* watchdog API.
*/
static int bfin_wdt_ioctl(struct inode *inode, struct file *file,
unsigned int cmd, unsigned long arg)
{
void __user *argp = (void __user *)arg;
int __user *p = argp;
stampit();
switch (cmd) {
default:
return -ENOTTY;
case WDIOC_GETSUPPORT:
if (copy_to_user(argp, &bfin_wdt_info, sizeof(bfin_wdt_info)))
return -EFAULT;
else
return 0;
case WDIOC_GETSTATUS:
case WDIOC_GETBOOTSTATUS:
return put_user(!!(_bfin_swrst & SWRST_RESET_WDOG), p);
case WDIOC_KEEPALIVE:
bfin_wdt_keepalive();
return 0;
case WDIOC_SETTIMEOUT: {
int new_timeout;
if (get_user(new_timeout, p))
return -EFAULT;
if (bfin_wdt_set_timeout(new_timeout))
return -EINVAL;
}
/* Fall */
case WDIOC_GETTIMEOUT:
return put_user(timeout, p);
case WDIOC_SETOPTIONS: {
unsigned long flags;
int options, ret = -EINVAL;
if (get_user(options, p))
return -EFAULT;
spin_lock_irqsave(&bfin_wdt_spinlock, flags);
if (options & WDIOS_DISABLECARD) {
bfin_wdt_stop();
ret = 0;
}
if (options & WDIOS_ENABLECARD) {
bfin_wdt_start();
ret = 0;
}
spin_unlock_irqrestore(&bfin_wdt_spinlock, flags);
return ret;
}
}
}
/**
* bfin_wdt_notify_sys - Notifier Handler
* @this: notifier block
* @code: notifier event
* @unused: unused
*
* Handles specific events, such as turning off the watchdog during a
* shutdown event.
*/
static int bfin_wdt_notify_sys(struct notifier_block *this, unsigned long code,
void *unused)
{
stampit();
if (code == SYS_DOWN || code == SYS_HALT)
bfin_wdt_stop();
return NOTIFY_DONE;
}
#ifdef CONFIG_PM
static int state_before_suspend;
/**
* bfin_wdt_suspend - suspend the watchdog
* @pdev: device being suspended
* @state: requested suspend state
*
* Remember if the watchdog was running and stop it.
* TODO: is this even right? Doesn't seem to be any
* standard in the watchdog world ...
*/
static int bfin_wdt_suspend(struct platform_device *pdev, pm_message_t state)
{
stampit();
state_before_suspend = bfin_wdt_running();
bfin_wdt_stop();
return 0;
}
/**
* bfin_wdt_resume - resume the watchdog
* @pdev: device being resumed
*
* If the watchdog was running, turn it back on.
*/
static int bfin_wdt_resume(struct platform_device *pdev)
{
stampit();
if (state_before_suspend) {
bfin_wdt_set_timeout(timeout);
bfin_wdt_start();
}
return 0;
}
#else
# define bfin_wdt_suspend NULL
# define bfin_wdt_resume NULL
#endif
static struct platform_device bfin_wdt_device = {
.name = WATCHDOG_NAME,
.id = -1,
};
static struct platform_driver bfin_wdt_driver = {
.driver = {
.name = WATCHDOG_NAME,
.owner = THIS_MODULE,
},
.suspend = bfin_wdt_suspend,
.resume = bfin_wdt_resume,
};
static const struct file_operations bfin_wdt_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
.write = bfin_wdt_write,
.ioctl = bfin_wdt_ioctl,
.open = bfin_wdt_open,
.release = bfin_wdt_release,
};
static struct miscdevice bfin_wdt_miscdev = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &bfin_wdt_fops,
};
static struct watchdog_info bfin_wdt_info = {
.identity = "Blackfin Watchdog",
.options = WDIOF_SETTIMEOUT |
WDIOF_KEEPALIVEPING |
WDIOF_MAGICCLOSE,
};
static struct notifier_block bfin_wdt_notifier = {
.notifier_call = bfin_wdt_notify_sys,
};
/**
* bfin_wdt_init - Initialize module
*
* Registers the device and notifier handler. Actual device
* initialization is handled by bfin_wdt_open().
*/
static int __init bfin_wdt_init(void)
{
int ret;
stampit();
/* Check that the timeout value is within range */
if (bfin_wdt_set_timeout(timeout))
return -EINVAL;
/* Since this is an on-chip device and needs no board-specific
* resources, we'll handle all the platform device stuff here.
*/
ret = platform_device_register(&bfin_wdt_device);
if (ret)
return ret;
ret = platform_driver_probe(&bfin_wdt_driver, NULL);
if (ret)
return ret;
ret = register_reboot_notifier(&bfin_wdt_notifier);
if (ret) {
pr_init(KERN_ERR PFX "cannot register reboot notifier (err=%d)\n", ret);
return ret;
}
ret = misc_register(&bfin_wdt_miscdev);
if (ret) {
pr_init(KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n",
WATCHDOG_MINOR, ret);
unregister_reboot_notifier(&bfin_wdt_notifier);
return ret;
}
pr_init(KERN_INFO PFX "initialized: timeout=%d sec (nowayout=%d)\n",
timeout, nowayout);
return 0;
}
/**
* bfin_wdt_exit - Deinitialize module
*
* Unregisters the device and notifier handler. Actual device
* deinitialization is handled by bfin_wdt_close().
*/
static void __exit bfin_wdt_exit(void)
{
misc_deregister(&bfin_wdt_miscdev);
unregister_reboot_notifier(&bfin_wdt_notifier);
}
module_init(bfin_wdt_init);
module_exit(bfin_wdt_exit);
MODULE_AUTHOR("Michele d'Amico, Mike Frysinger <vapier@gentoo.org>");
MODULE_DESCRIPTION("Blackfin Watchdog Device Driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
module_param(timeout, uint, 0);
MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. (1<=timeout<=((2^32)/SCLK), default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
module_param(nowayout, int, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
