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ar7_wdt.c
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ar7_wdt.c
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/*
* drivers/watchdog/ar7_wdt.c
*
* Copyright (C) 2007 Nicolas Thill <[email protected]>
* Copyright (c) 2005 Enrik Berkhan <[email protected]>
*
* Some code taken from:
* National Semiconductor SCx200 Watchdog support
* Copyright (c) 2001,2002 Christer Weinigel <[email protected]>
*
* 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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/miscdevice.h>
#include <linux/platform_device.h>
#include <linux/watchdog.h>
#include <linux/fs.h>
#include <linux/ioport.h>
#include <linux/io.h>
#include <linux/uaccess.h>
#include <linux/clk.h>
#include <asm/addrspace.h>
#include <asm/mach-ar7/ar7.h>
#define DRVNAME "ar7_wdt"
#define LONGNAME "TI AR7 Watchdog Timer"
MODULE_AUTHOR("Nicolas Thill <[email protected]>");
MODULE_DESCRIPTION(LONGNAME);
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
static int margin = 60;
module_param(margin, int, 0);
MODULE_PARM_DESC(margin, "Watchdog margin in seconds");
static int nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, int, 0);
MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
#define READ_REG(x) readl((void __iomem *)&(x))
#define WRITE_REG(x, v) writel((v), (void __iomem *)&(x))
struct ar7_wdt {
u32 kick_lock;
u32 kick;
u32 change_lock;
u32 change;
u32 disable_lock;
u32 disable;
u32 prescale_lock;
u32 prescale;
};
static unsigned long wdt_is_open;
static spinlock_t wdt_lock;
static unsigned expect_close;
/* XXX currently fixed, allows max margin ~68.72 secs */
#define prescale_value 0xffff
/* Resource of the WDT registers */
static struct resource *ar7_regs_wdt;
/* Pointer to the remapped WDT IO space */
static struct ar7_wdt *ar7_wdt;
static struct clk *vbus_clk;
static void ar7_wdt_kick(u32 value)
{
WRITE_REG(ar7_wdt->kick_lock, 0x5555);
if ((READ_REG(ar7_wdt->kick_lock) & 3) == 1) {
WRITE_REG(ar7_wdt->kick_lock, 0xaaaa);
if ((READ_REG(ar7_wdt->kick_lock) & 3) == 3) {
WRITE_REG(ar7_wdt->kick, value);
return;
}
}
printk(KERN_ERR DRVNAME ": failed to unlock WDT kick reg\n");
}
static void ar7_wdt_prescale(u32 value)
{
WRITE_REG(ar7_wdt->prescale_lock, 0x5a5a);
if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 1) {
WRITE_REG(ar7_wdt->prescale_lock, 0xa5a5);
if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 3) {
WRITE_REG(ar7_wdt->prescale, value);
return;
}
}
printk(KERN_ERR DRVNAME ": failed to unlock WDT prescale reg\n");
}
static void ar7_wdt_change(u32 value)
{
WRITE_REG(ar7_wdt->change_lock, 0x6666);
if ((READ_REG(ar7_wdt->change_lock) & 3) == 1) {
WRITE_REG(ar7_wdt->change_lock, 0xbbbb);
if ((READ_REG(ar7_wdt->change_lock) & 3) == 3) {
WRITE_REG(ar7_wdt->change, value);
return;
}
}
printk(KERN_ERR DRVNAME ": failed to unlock WDT change reg\n");
}
static void ar7_wdt_disable(u32 value)
{
WRITE_REG(ar7_wdt->disable_lock, 0x7777);
if ((READ_REG(ar7_wdt->disable_lock) & 3) == 1) {
WRITE_REG(ar7_wdt->disable_lock, 0xcccc);
if ((READ_REG(ar7_wdt->disable_lock) & 3) == 2) {
WRITE_REG(ar7_wdt->disable_lock, 0xdddd);
if ((READ_REG(ar7_wdt->disable_lock) & 3) == 3) {
WRITE_REG(ar7_wdt->disable, value);
return;
}
}
}
printk(KERN_ERR DRVNAME ": failed to unlock WDT disable reg\n");
}
static void ar7_wdt_update_margin(int new_margin)
{
u32 change;
u32 vbus_rate;
vbus_rate = clk_get_rate(vbus_clk);
change = new_margin * (vbus_rate / prescale_value);
if (change < 1)
change = 1;
if (change > 0xffff)
change = 0xffff;
ar7_wdt_change(change);
margin = change * prescale_value / vbus_rate;
printk(KERN_INFO DRVNAME
": timer margin %d seconds (prescale %d, change %d, freq %d)\n",
margin, prescale_value, change, vbus_rate);
}
static void ar7_wdt_enable_wdt(void)
{
printk(KERN_DEBUG DRVNAME ": enabling watchdog timer\n");
ar7_wdt_disable(1);
ar7_wdt_kick(1);
}
static void ar7_wdt_disable_wdt(void)
{
printk(KERN_DEBUG DRVNAME ": disabling watchdog timer\n");
ar7_wdt_disable(0);
}
static int ar7_wdt_open(struct inode *inode, struct file *file)
{
/* only allow one at a time */
if (test_and_set_bit(0, &wdt_is_open))
return -EBUSY;
ar7_wdt_enable_wdt();
expect_close = 0;
return nonseekable_open(inode, file);
}
static int ar7_wdt_release(struct inode *inode, struct file *file)
{
if (!expect_close)
printk(KERN_WARNING DRVNAME
": watchdog device closed unexpectedly,"
"will not disable the watchdog timer\n");
else if (!nowayout)
ar7_wdt_disable_wdt();
clear_bit(0, &wdt_is_open);
return 0;
}
static ssize_t ar7_wdt_write(struct file *file, const char *data,
size_t len, loff_t *ppos)
{
/* check for a magic close character */
if (len) {
size_t i;
spin_lock(&wdt_lock);
ar7_wdt_kick(1);
spin_unlock(&wdt_lock);
expect_close = 0;
for (i = 0; i < len; ++i) {
char c;
if (get_user(c, data + i))
return -EFAULT;
if (c == 'V')
expect_close = 1;
}
}
return len;
}
static long ar7_wdt_ioctl(struct file *file,
unsigned int cmd, unsigned long arg)
{
static const struct watchdog_info ident = {
.identity = LONGNAME,
.firmware_version = 1,
.options = (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
WDIOF_MAGICCLOSE),
};
int new_margin;
switch (cmd) {
case WDIOC_GETSUPPORT:
if (copy_to_user((struct watchdog_info *)arg, &ident,
sizeof(ident)))
return -EFAULT;
return 0;
case WDIOC_GETSTATUS:
case WDIOC_GETBOOTSTATUS:
if (put_user(0, (int *)arg))
return -EFAULT;
return 0;
case WDIOC_KEEPALIVE:
ar7_wdt_kick(1);
return 0;
case WDIOC_SETTIMEOUT:
if (get_user(new_margin, (int *)arg))
return -EFAULT;
if (new_margin < 1)
return -EINVAL;
spin_lock(&wdt_lock);
ar7_wdt_update_margin(new_margin);
ar7_wdt_kick(1);
spin_unlock(&wdt_lock);
case WDIOC_GETTIMEOUT:
if (put_user(margin, (int *)arg))
return -EFAULT;
return 0;
default:
return -ENOTTY;
}
}
static const struct file_operations ar7_wdt_fops = {
.owner = THIS_MODULE,
.write = ar7_wdt_write,
.unlocked_ioctl = ar7_wdt_ioctl,
.open = ar7_wdt_open,
.release = ar7_wdt_release,
.llseek = no_llseek,
};
static struct miscdevice ar7_wdt_miscdev = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &ar7_wdt_fops,
};
static int __devinit ar7_wdt_probe(struct platform_device *pdev)
{
int rc;
spin_lock_init(&wdt_lock);
ar7_regs_wdt =
platform_get_resource_byname(pdev, IORESOURCE_MEM, "regs");
if (!ar7_regs_wdt) {
printk(KERN_ERR DRVNAME ": could not get registers resource\n");
rc = -ENODEV;
goto out;
}
if (!request_mem_region(ar7_regs_wdt->start,
resource_size(ar7_regs_wdt), LONGNAME)) {
printk(KERN_WARNING DRVNAME ": watchdog I/O region busy\n");
rc = -EBUSY;
goto out;
}
ar7_wdt = ioremap(ar7_regs_wdt->start, resource_size(ar7_regs_wdt));
if (!ar7_wdt) {
printk(KERN_ERR DRVNAME ": could not ioremap registers\n");
rc = -ENXIO;
goto out_mem_region;
}
vbus_clk = clk_get(NULL, "vbus");
if (IS_ERR(vbus_clk)) {
printk(KERN_ERR DRVNAME ": could not get vbus clock\n");
rc = PTR_ERR(vbus_clk);
goto out_mem_region;
}
ar7_wdt_disable_wdt();
ar7_wdt_prescale(prescale_value);
ar7_wdt_update_margin(margin);
rc = misc_register(&ar7_wdt_miscdev);
if (rc) {
printk(KERN_ERR DRVNAME ": unable to register misc device\n");
goto out_alloc;
}
goto out;
out_alloc:
iounmap(ar7_wdt);
out_mem_region:
release_mem_region(ar7_regs_wdt->start, resource_size(ar7_regs_wdt));
out:
return rc;
}
static int __devexit ar7_wdt_remove(struct platform_device *pdev)
{
misc_deregister(&ar7_wdt_miscdev);
iounmap(ar7_wdt);
release_mem_region(ar7_regs_wdt->start, resource_size(ar7_regs_wdt));
return 0;
}
static void ar7_wdt_shutdown(struct platform_device *pdev)
{
if (!nowayout)
ar7_wdt_disable_wdt();
}
static struct platform_driver ar7_wdt_driver = {
.probe = ar7_wdt_probe,
.remove = __devexit_p(ar7_wdt_remove),
.shutdown = ar7_wdt_shutdown,
.driver = {
.owner = THIS_MODULE,
.name = "ar7_wdt",
},
};
static int __init ar7_wdt_init(void)
{
return platform_driver_register(&ar7_wdt_driver);
}
static void __exit ar7_wdt_cleanup(void)
{
platform_driver_unregister(&ar7_wdt_driver);
}
module_init(ar7_wdt_init);
module_exit(ar7_wdt_cleanup);