/* linux/drivers/char/watchdog/s3c2410_wdt.c
*
* Copyright (c) 2004 Simtec Electronics
* Ben Dooks <ben@simtec.co.uk>
*
* S3C2410 Watchdog Timer Support
*
* Based on, softdog.c by Alan Cox,
* (c) Copyright 1996 Alan Cox <alan@redhat.com>
*
* 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.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* Changelog:
* 05-Oct-2004 BJD Added semaphore init to stop crashes on open
* Fixed tmr_count / wdt_count confusion
* Added configurable debug
*
* 11-Jan-2005 BJD Fixed divide-by-2 in timeout code
*
* 25-Jan-2005 DA Added suspend/resume support
* Replaced reboot notifier with .shutdown method
*
* 10-Mar-2005 LCVR Changed S3C2410_VA to S3C24XX_VA
*/
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/config.h>
#include <linux/types.h>
#include <linux/timer.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/interrupt.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#include <asm/arch/map.h>
#include <asm/hardware/clock.h>
#undef S3C24XX_VA_WATCHDOG
#define S3C24XX_VA_WATCHDOG (0)
#include <asm/arch/regs-watchdog.h>
#define PFX "s3c2410-wdt: "
#define CONFIG_S3C2410_WATCHDOG_ATBOOT (0)
#define CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME (15)
static int nowayout = WATCHDOG_NOWAYOUT;
static int tmr_margin = CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME;
static int tmr_atboot = CONFIG_S3C2410_WATCHDOG_ATBOOT;
static int soft_noboot = 0;
static int debug = 0;
module_param(tmr_margin, int, 0);
module_param(tmr_atboot, int, 0);
module_param(nowayout, int, 0);
module_param(soft_noboot, int, 0);
module_param(debug, int, 0);
MODULE_PARM_DESC(tmr_margin, "Watchdog tmr_margin in seconds. default=" __MODULE_STRING(CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME) ")");
MODULE_PARM_DESC(tmr_atboot, "Watchdog is started at boot time if set to 1, default=" __MODULE_STRING(CONFIG_S3C2410_WATCHDOG_ATBOOT));
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=CONFIG_WATCHDOG_NOWAYOUT)");
MODULE_PARM_DESC(soft_noboot, "Watchdog action, set to 1 to ignore reboots, 0 to reboot (default depends on ONLY_TESTING)");
MODULE_PARM_DESC(debug, "Watchdog debug, set to >1 for debug, (default 0)");
typedef enum close_state {
CLOSE_STATE_NOT,
CLOSE_STATE_ALLOW=0x4021
} close_state_t;
static DECLARE_MUTEX(open_lock);
static struct resource *wdt_mem;
static struct resource *wdt_irq;
static struct clk *wdt_clock;
static void __iomem *wdt_base;
static unsigned int wdt_count;
static close_state_t allow_close;
/* watchdog control routines */
#define DBG(msg...) do { \
if (debug) \
printk(KERN_INFO msg); \
} while(0)
/* functions */
static int s3c2410wdt_keepalive(void)
{
writel(wdt_count, wdt_base + S3C2410_WTCNT);
return 0;
}
static int s3c2410wdt_stop(void)
{
unsigned long wtcon;
wtcon = readl(wdt_base + S3C2410_WTCON);
wtcon &= ~(S3C2410_WTCON_ENABLE | S3C2410_WTCON_RSTEN);
writel(wtcon, wdt_base + S3C2410_WTCON);
return 0;
}
static int s3c2410wdt_start(void)
{
unsigned long wtcon;
s3c2410wdt_stop();
wtcon = readl(wdt_base + S3C2410_WTCON);
wtcon |= S3C2410_WTCON_ENABLE | S3C2410_WTCON_DIV128;
if (soft_noboot) {
wtcon |= S3C2410_WTCON_INTEN;
wtcon &= ~S3C2410_WTCON_RSTEN;
} else {
wtcon &= ~S3C2410_WTCON_INTEN;
wtcon |= S3C2410_WTCON_RSTEN;
}
DBG("%s: wdt_count=0x%08x, wtcon=%08lx\n",
__FUNCTION__, wdt_count, wtcon);
writel(wdt_count, wdt_base + S3C2410_WTDAT);
writel(wdt_count, wdt_base + S3C2410_WTCNT);
writel(wtcon, wdt_base + S3C2410_WTCON);
return 0;
}
static int s3c2410wdt_set_heartbeat(int timeout)
{
unsigned int freq = clk_get_rate(wdt_clock);
unsigned int count;
unsigned int divisor = 1;
unsigned long wtcon;
if (timeout < 1)
return -EINVAL;
freq /= 128;
count = timeout * freq;
DBG("%s: count=%d, timeout=%d, freq=%d\n",
__FUNCTION__, count, timeout, freq);
/* if the count is bigger than the watchdog register,
then work out what we need to do (and if) we can
actually make this value
*/
if (count >= 0x10000) {
for (divisor = 1; divisor <= 0x100; divisor++) {
if ((count / divisor) < 0x10000)
break;
}
if ((count / divisor) >= 0x10000) {
printk(KERN_ERR PFX "timeout %d too big\n", timeout);
return -EINVAL;
}
}
tmr_margin = timeout;
DBG("%s: timeout=%d, divisor=%d, count=%d (%08x)\n",
__FUNCTION__, timeout, divisor, count, count/divisor);
count /= divisor;
wdt_count = count;
/* update the pre-scaler */
wtcon = readl(wdt_base + S3C2410_WTCON);
wtcon &= ~S3C2410_WTCON_PRESCALE_MASK;
wtcon |= S3C2410_WTCON_PRESCALE(divisor-1);
writel(count, wdt_base + S3C2410_WTDAT);
writel(wtcon, wdt_base + S3C2410_WTCON);
return 0;
}
/*
* /dev/watchdog handling
*/
static int s3c2410wdt_open(struct inode *inode, struct file *file)
{
if(down_trylock(&open_lock))
return -EBUSY;
if (nowayout) {
__module_get(THIS_MODULE);
} else {
allow_close = CLOSE_STATE_ALLOW;
}
/* start the timer */
s3c2410wdt_start();
return nonseekable_open(inode, file);
}
static int s3c2410wdt_release(struct inode *inode, struct file *file)
{
/*
* Shut off the timer.
* Lock it in if it's a module and we set nowayout
*/
if (allow_close == CLOSE_STATE_ALLOW) {
s3c2410wdt_stop();
} else {
printk(KERN_CRIT PFX "Unexpected close, not stopping watchdog!\n");
s3c2410wdt_keepalive();
}
allow_close = CLOSE_STATE_NOT;
up(&open_lock);
return 0;
}
static ssize_t s3c2410wdt_write(struct file *file, const char __user *data,
size_t len, loff_t *ppos)
{
/*
* Refresh the timer.
*/
if(len) {
if (!nowayout) {
size_t i;
/* In case it was set long ago */
allow_close = CLOSE_STATE_NOT;
for (i = 0; i != len; i++) {
char c;
if (get_user(c, data + i))
return -EFAULT;
if (c == 'V')
allow_close = CLOSE_STATE_ALLOW;
}
}
s3c2410wdt_keepalive();
}
return len;
}
#define OPTIONS WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE
static struct watchdog_info s3c2410_wdt_ident = {
.options = OPTIONS,
.firmware_version = 0,
.identity = "S3C2410 Watchdog",
};
static int s3c2410wdt_ioctl(struct inode *inode, struct file *file,
unsigned int cmd, unsigned long arg)
{
void __user *argp = (void __user *)arg;
int __user *p = argp;
int new_margin;
switch (cmd) {
default:
return -ENOIOCTLCMD;
case WDIOC_GETSUPPORT:
return copy_to_user(argp, &s3c2410_wdt_ident,
sizeof(s3c2410_wdt_ident)) ? -EFAULT : 0;
case WDIOC_GETSTATUS:
case WDIOC_GETBOOTSTATUS:
return put_user(0, p);
case WDIOC_KEEPALIVE:
s3c2410wdt_keepalive();
return 0;
case WDIOC_SETTIMEOUT:
if (get_user(new_margin, p))
return -EFAULT;
if (s3c2410wdt_set_heartbeat(new_margin))
return -EINVAL;
s3c2410wdt_keepalive();
return put_user(tmr_margin, p);
case WDIOC_GETTIMEOUT:
return put_user(tmr_margin, p);
}
}
/* kernel interface */
static struct file_operations s3c2410wdt_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
.write = s3c2410wdt_write,
.ioctl = s3c2410wdt_ioctl,
.open = s3c2410wdt_open,
.release = s3c2410wdt_release,
};
static struct miscdevice s3c2410wdt_miscdev = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &s3c2410wdt_fops,
};
/* interrupt handler code */
static irqreturn_t s3c2410wdt_irq(int irqno, void *param,
struct pt_regs *regs)
{
printk(KERN_INFO PFX "Watchdog timer expired!\n");
s3c2410wdt_keepalive();
return IRQ_HANDLED;
}
/* device interface */
static int s3c2410wdt_probe(struct device *dev)
{
struct platform_device *pdev = to_platform_device(dev);
struct resource *res;
int started = 0;
int ret;
int size;
DBG("%s: probe=%p, device=%p\n", __FUNCTION__, pdev, dev);
/* get the memory region for the watchdog timer */
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (res == NULL) {
printk(KERN_INFO PFX "failed to get memory region resouce\n");
return -ENOENT;
}
size = (res->end-res->start)+1;
wdt_mem = request_mem_region(res->start, size, pdev->name);
if (wdt_mem == NULL) {
printk(KERN_INFO PFX "failed to get memory region\n");
return -ENOENT;
}
wdt_base = ioremap(res->start, size);
if (wdt_base == 0) {
printk(KERN_INFO PFX "failed to ioremap() region\n");
return -EINVAL;
}
DBG("probe: mapped wdt_base=%p\n", wdt_base);
res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
if (res == NULL) {
printk(KERN_INFO PFX "failed to get irq resource\n");
return -ENOENT;
}
ret = request_irq(res->start, s3c2410wdt_irq, 0, pdev->name, dev);
if (ret != 0) {
printk(KERN_INFO PFX "failed to install irq (%d)\n", ret);
return ret;
}
wdt_clock = clk_get(dev, "watchdog");
if (wdt_clock == NULL) {
printk(KERN_INFO PFX "failed to find watchdog clock source\n");
return -ENOENT;
}
clk_use(wdt_clock);
clk_enable(wdt_clock);
/* see if we can actually set the requested timer margin, and if
* not, try the default value */
if (s3c2410wdt_set_heartbeat(tmr_margin)) {
started = s3c2410wdt_set_heartbeat(CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME);
if (started == 0) {
printk(KERN_INFO PFX "tmr_margin value out of range, default %d used\n",
CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME);
} else {
printk(KERN_INFO PFX "default timer value is out of range, cannot start\n");
}
}
ret = misc_register(&s3c2410wdt_miscdev);
if (ret) {
printk (KERN_ERR PFX "cannot register miscdev on minor=%d (%d)\n",
WATCHDOG_MINOR, ret);
return ret;
}
if (tmr_atboot && started == 0) {
printk(KERN_INFO PFX "Starting Watchdog Timer\n");
s3c2410wdt_start();
}
return 0;
}
static int s3c2410wdt_remove(struct device *dev)
{
if (wdt_mem != NULL) {
release_resource(wdt_mem);
kfree(wdt_mem);
wdt_mem = NULL;
}
if (wdt_irq != NULL) {
free_irq(wdt_irq->start, dev);
wdt_irq = NULL;
}
if (wdt_clock != NULL) {
clk_disable(wdt_clock);
clk_unuse(wdt_clock);
clk_put(wdt_clock);
wdt_clock = NULL;
}
misc_deregister(&s3c2410wdt_miscdev);
return 0;
}
static void s3c2410wdt_shutdown(struct device *dev)
{
s3c2410wdt_stop();
}
#ifdef CONFIG_PM
static unsigned long wtcon_save;
static unsigned long wtdat_save;
static int s3c2410wdt_suspend(struct device *dev, pm_message_t state, u32 level)
{
if (level == SUSPEND_POWER_DOWN) {
/* Save watchdog state, and turn it off. */
wtcon_save = readl(wdt_base + S3C2410_WTCON);
wtdat_save = readl(wdt_base + S3C2410_WTDAT);
/* Note that WTCNT doesn't need to be saved. */
s3c2410wdt_stop();
}
return 0;
}
static int s3c2410wdt_resume(struct device *dev, u32 level)
{
if (level == RESUME_POWER_ON) {
/* Restore watchdog state. */
writel(wtdat_save, wdt_base + S3C2410_WTDAT);
writel(wtdat_save, wdt_base + S3C2410_WTCNT); /* Reset count */
writel(wtcon_save, wdt_base + S3C2410_WTCON);
printk(KERN_INFO PFX "watchdog %sabled\n",
(wtcon_save & S3C2410_WTCON_ENABLE) ? "en" : "dis");
}
return 0;
}
#else
#define s3c2410wdt_suspend NULL
#define s3c2410wdt_resume NULL
#endif /* CONFIG_PM */
static struct device_driver s3c2410wdt_driver = {
.name = "s3c2410-wdt",
.bus = &platform_bus_type,
.probe = s3c2410wdt_probe,
.remove = s3c2410wdt_remove,
.shutdown = s3c2410wdt_shutdown,
.suspend = s3c2410wdt_suspend,
.resume = s3c2410wdt_resume,
};
static char banner[] __initdata = KERN_INFO "S3C2410 Watchdog Timer, (c) 2004 Simtec Electronics\n";
static int __init watchdog_init(void)
{
printk(banner);
return driver_register(&s3c2410wdt_driver);
}
static void __exit watchdog_exit(void)
{
driver_unregister(&s3c2410wdt_driver);
}
module_init(watchdog_init);
module_exit(watchdog_exit);
MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>, "
"Dimitry Andric <dimitry.andric@tomtom.com>");
MODULE_DESCRIPTION("S3C2410 Watchdog Device Driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
