linux/drivers/watchdog/lantiq_wdt.c
John Crispin 9cfce47b14 watchdog: lantiq: fix watchdogs timeout handling
The enable function was using the global timeout variable for local operations.
This resulted in the value of the global variable being corrupted, thus
breaking the code.

Signed-off-by: John Crispin <blogic@openwrt.org>
Signed-off-by: Thomas Langer <thomas.langer@lantiq.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Cc: linux-watchdog@vger.kernel.org
Cc: linux-mips@linux-mips.org
2011-09-20 14:28:24 +02:00

262 lines
6.1 KiB
C

/*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as published
* by the Free Software Foundation.
*
* Copyright (C) 2010 John Crispin <blogic@openwrt.org>
* Based on EP93xx wdt driver
*/
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/platform_device.h>
#include <linux/uaccess.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <lantiq.h>
/* Section 3.4 of the datasheet
* The password sequence protects the WDT control register from unintended
* write actions, which might cause malfunction of the WDT.
*
* essentially the following two magic passwords need to be written to allow
* IO access to the WDT core
*/
#define LTQ_WDT_PW1 0x00BE0000
#define LTQ_WDT_PW2 0x00DC0000
#define LTQ_WDT_CR 0x0 /* watchdog control register */
#define LTQ_WDT_SR 0x8 /* watchdog status register */
#define LTQ_WDT_SR_EN (0x1 << 31) /* enable bit */
#define LTQ_WDT_SR_PWD (0x3 << 26) /* turn on power */
#define LTQ_WDT_SR_CLKDIV (0x3 << 24) /* turn on clock and set */
/* divider to 0x40000 */
#define LTQ_WDT_DIVIDER 0x40000
#define LTQ_MAX_TIMEOUT ((1 << 16) - 1) /* the reload field is 16 bit */
static int nowayout = WATCHDOG_NOWAYOUT;
static void __iomem *ltq_wdt_membase;
static unsigned long ltq_io_region_clk_rate;
static unsigned long ltq_wdt_bootstatus;
static unsigned long ltq_wdt_in_use;
static int ltq_wdt_timeout = 30;
static int ltq_wdt_ok_to_close;
static void
ltq_wdt_enable(void)
{
unsigned long int timeout = ltq_wdt_timeout *
(ltq_io_region_clk_rate / LTQ_WDT_DIVIDER) + 0x1000;
if (timeout > LTQ_MAX_TIMEOUT)
timeout = LTQ_MAX_TIMEOUT;
/* write the first password magic */
ltq_w32(LTQ_WDT_PW1, ltq_wdt_membase + LTQ_WDT_CR);
/* write the second magic plus the configuration and new timeout */
ltq_w32(LTQ_WDT_SR_EN | LTQ_WDT_SR_PWD | LTQ_WDT_SR_CLKDIV |
LTQ_WDT_PW2 | timeout, ltq_wdt_membase + LTQ_WDT_CR);
}
static void
ltq_wdt_disable(void)
{
/* write the first password magic */
ltq_w32(LTQ_WDT_PW1, ltq_wdt_membase + LTQ_WDT_CR);
/* write the second password magic with no config
* this turns the watchdog off
*/
ltq_w32(LTQ_WDT_PW2, ltq_wdt_membase + LTQ_WDT_CR);
}
static ssize_t
ltq_wdt_write(struct file *file, const char __user *data,
size_t len, loff_t *ppos)
{
if (len) {
if (!nowayout) {
size_t i;
ltq_wdt_ok_to_close = 0;
for (i = 0; i != len; i++) {
char c;
if (get_user(c, data + i))
return -EFAULT;
if (c == 'V')
ltq_wdt_ok_to_close = 1;
else
ltq_wdt_ok_to_close = 0;
}
}
ltq_wdt_enable();
}
return len;
}
static struct watchdog_info ident = {
.options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
WDIOF_CARDRESET,
.identity = "ltq_wdt",
};
static long
ltq_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_GETBOOTSTATUS:
ret = put_user(ltq_wdt_bootstatus, (int __user *)arg);
break;
case WDIOC_GETSTATUS:
ret = put_user(0, (int __user *)arg);
break;
case WDIOC_SETTIMEOUT:
ret = get_user(ltq_wdt_timeout, (int __user *)arg);
if (!ret)
ltq_wdt_enable();
/* intentional drop through */
case WDIOC_GETTIMEOUT:
ret = put_user(ltq_wdt_timeout, (int __user *)arg);
break;
case WDIOC_KEEPALIVE:
ltq_wdt_enable();
ret = 0;
break;
}
return ret;
}
static int
ltq_wdt_open(struct inode *inode, struct file *file)
{
if (test_and_set_bit(0, &ltq_wdt_in_use))
return -EBUSY;
ltq_wdt_in_use = 1;
ltq_wdt_enable();
return nonseekable_open(inode, file);
}
static int
ltq_wdt_release(struct inode *inode, struct file *file)
{
if (ltq_wdt_ok_to_close)
ltq_wdt_disable();
else
pr_err("ltq_wdt: watchdog closed without warning\n");
ltq_wdt_ok_to_close = 0;
clear_bit(0, &ltq_wdt_in_use);
return 0;
}
static const struct file_operations ltq_wdt_fops = {
.owner = THIS_MODULE,
.write = ltq_wdt_write,
.unlocked_ioctl = ltq_wdt_ioctl,
.open = ltq_wdt_open,
.release = ltq_wdt_release,
.llseek = no_llseek,
};
static struct miscdevice ltq_wdt_miscdev = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &ltq_wdt_fops,
};
static int __init
ltq_wdt_probe(struct platform_device *pdev)
{
struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
struct clk *clk;
if (!res) {
dev_err(&pdev->dev, "cannot obtain I/O memory region");
return -ENOENT;
}
res = devm_request_mem_region(&pdev->dev, res->start,
resource_size(res), dev_name(&pdev->dev));
if (!res) {
dev_err(&pdev->dev, "cannot request I/O memory region");
return -EBUSY;
}
ltq_wdt_membase = devm_ioremap_nocache(&pdev->dev, res->start,
resource_size(res));
if (!ltq_wdt_membase) {
dev_err(&pdev->dev, "cannot remap I/O memory region\n");
return -ENOMEM;
}
/* we do not need to enable the clock as it is always running */
clk = clk_get(&pdev->dev, "io");
WARN_ON(!clk);
ltq_io_region_clk_rate = clk_get_rate(clk);
clk_put(clk);
if (ltq_reset_cause() == LTQ_RST_CAUSE_WDTRST)
ltq_wdt_bootstatus = WDIOF_CARDRESET;
return misc_register(&ltq_wdt_miscdev);
}
static int __devexit
ltq_wdt_remove(struct platform_device *pdev)
{
misc_deregister(&ltq_wdt_miscdev);
if (ltq_wdt_membase)
iounmap(ltq_wdt_membase);
return 0;
}
static struct platform_driver ltq_wdt_driver = {
.remove = __devexit_p(ltq_wdt_remove),
.driver = {
.name = "ltq_wdt",
.owner = THIS_MODULE,
},
};
static int __init
init_ltq_wdt(void)
{
return platform_driver_probe(&ltq_wdt_driver, ltq_wdt_probe);
}
static void __exit
exit_ltq_wdt(void)
{
return platform_driver_unregister(&ltq_wdt_driver);
}
module_init(init_ltq_wdt);
module_exit(exit_ltq_wdt);
module_param(nowayout, int, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
MODULE_AUTHOR("John Crispin <blogic@openwrt.org>");
MODULE_DESCRIPTION("Lantiq SoC Watchdog");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);