/*
* 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, <q_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, <q_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 = <q_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(<q_wdt_miscdev);
}
static int __devexit
ltq_wdt_remove(struct platform_device *pdev)
{
misc_deregister(<q_wdt_miscdev);
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(<q_wdt_driver, ltq_wdt_probe);
}
static void __exit
exit_ltq_wdt(void)
{
return platform_driver_unregister(<q_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);
