/*
* Copyright 2010-2011 Picochip Ltd., Jamie Iles
* http://www.picochip.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 file implements a driver for the Synopsys DesignWare watchdog device
* in the many subsystems. The watchdog has 16 different timeout periods
* and these are a function of the input clock frequency.
*
* The DesignWare watchdog cannot be stopped once it has been started so we
* use a software timer to implement a ping that will keep the watchdog alive.
* If we receive an expected close for the watchdog then we keep the timer
* running, otherwise the timer is stopped and the watchdog will expire.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/bitops.h>
#include <linux/clk.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/fs.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/of.h>
#include <linux/pm.h>
#include <linux/platform_device.h>
#include <linux/spinlock.h>
#include <linux/timer.h>
#include <linux/uaccess.h>
#include <linux/watchdog.h>
#define WDOG_CONTROL_REG_OFFSET 0x00
#define WDOG_CONTROL_REG_WDT_EN_MASK 0x01
#define WDOG_TIMEOUT_RANGE_REG_OFFSET 0x04
#define WDOG_CURRENT_COUNT_REG_OFFSET 0x08
#define WDOG_COUNTER_RESTART_REG_OFFSET 0x0c
#define WDOG_COUNTER_RESTART_KICK_VALUE 0x76
/* The maximum TOP (timeout period) value that can be set in the watchdog. */
#define DW_WDT_MAX_TOP 15
static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
"(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
#define WDT_TIMEOUT (HZ / 2)
static struct {
spinlock_t lock;
void __iomem *regs;
struct clk *clk;
unsigned long in_use;
unsigned long next_heartbeat;
struct timer_list timer;
int expect_close;
} dw_wdt;
static inline int dw_wdt_is_enabled(void)
{
return readl(dw_wdt.regs + WDOG_CONTROL_REG_OFFSET) &
WDOG_CONTROL_REG_WDT_EN_MASK;
}
static inline int dw_wdt_top_in_seconds(unsigned top)
{
/*
* There are 16 possible timeout values in 0..15 where the number of
* cycles is 2 ^ (16 + i) and the watchdog counts down.
*/
return (1 << (16 + top)) / clk_get_rate(dw_wdt.clk);
}
static int dw_wdt_get_top(void)
{
int top = readl(dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET) & 0xF;
return dw_wdt_top_in_seconds(top);
}
static inline void dw_wdt_set_next_heartbeat(void)
{
dw_wdt.next_heartbeat = jiffies + dw_wdt_get_top() * HZ;
}
static int dw_wdt_set_top(unsigned top_s)
{
int i, top_val = DW_WDT_MAX_TOP;
/*
* Iterate over the timeout values until we find the closest match. We
* always look for >=.
*/
for (i = 0; i <= DW_WDT_MAX_TOP; ++i)
if (dw_wdt_top_in_seconds(i) >= top_s) {
top_val = i;
break;
}
/* Set the new value in the watchdog. */
writel(top_val, dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
dw_wdt_set_next_heartbeat();
return dw_wdt_top_in_seconds(top_val);
}
static void dw_wdt_keepalive(void)
{
writel(WDOG_COUNTER_RESTART_KICK_VALUE, dw_wdt.regs +
WDOG_COUNTER_RESTART_REG_OFFSET);
}
static void dw_wdt_ping(unsigned long data)
{
if (time_before(jiffies, dw_wdt.next_heartbeat) ||
(!nowayout && !dw_wdt.in_use)) {
dw_wdt_keepalive();
mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);
} else
pr_crit("keepalive missed, machine will reset\n");
}
static int dw_wdt_open(struct inode *inode, struct file *filp)
{
if (test_and_set_bit(0, &dw_wdt.in_use))
return -EBUSY;
/* Make sure we don't get unloaded. */
__module_get(THIS_MODULE);
spin_lock(&dw_wdt.lock);
if (!dw_wdt_is_enabled()) {
/*
* The watchdog is not currently enabled. Set the timeout to
* the maximum and then start it.
*/
dw_wdt_set_top(DW_WDT_MAX_TOP);
writel(WDOG_CONTROL_REG_WDT_EN_MASK,
dw_wdt.regs + WDOG_CONTROL_REG_OFFSET);
}
dw_wdt_set_next_heartbeat();
spin_unlock(&dw_wdt.lock);
return nonseekable_open(inode, filp);
}
static ssize_t dw_wdt_write(struct file *filp, const char __user *buf,
size_t len, loff_t *offset)
{
if (!len)
return 0;
if (!nowayout) {
size_t i;
dw_wdt.expect_close = 0;
for (i = 0; i < len; ++i) {
char c;
if (get_user(c, buf + i))
return -EFAULT;
if (c == 'V') {
dw_wdt.expect_close = 1;
break;
}
}
}
dw_wdt_set_next_heartbeat();
mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);
return len;
}
static u32 dw_wdt_time_left(void)
{
return readl(dw_wdt.regs + WDOG_CURRENT_COUNT_REG_OFFSET) /
clk_get_rate(dw_wdt.clk);
}
static const struct watchdog_info dw_wdt_ident = {
.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
WDIOF_MAGICCLOSE,
.identity = "Synopsys DesignWare Watchdog",
};
static long dw_wdt_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
unsigned long val;
int timeout;
switch (cmd) {
case WDIOC_GETSUPPORT:
return copy_to_user((void __user *)arg, &dw_wdt_ident,
sizeof(dw_wdt_ident)) ? -EFAULT : 0;
case WDIOC_GETSTATUS:
case WDIOC_GETBOOTSTATUS:
return put_user(0, (int __user *)arg);
case WDIOC_KEEPALIVE:
dw_wdt_set_next_heartbeat();
return 0;
case WDIOC_SETTIMEOUT:
if (get_user(val, (int __user *)arg))
return -EFAULT;
timeout = dw_wdt_set_top(val);
return put_user(timeout , (int __user *)arg);
case WDIOC_GETTIMEOUT:
return put_user(dw_wdt_get_top(), (int __user *)arg);
case WDIOC_GETTIMELEFT:
/* Get the time left until expiry. */
if (get_user(val, (int __user *)arg))
return -EFAULT;
return put_user(dw_wdt_time_left(), (int __user *)arg);
default:
return -ENOTTY;
}
}
static int dw_wdt_release(struct inode *inode, struct file *filp)
{
clear_bit(0, &dw_wdt.in_use);
if (!dw_wdt.expect_close) {
del_timer(&dw_wdt.timer);
if (!nowayout)
pr_crit("unexpected close, system will reboot soon\n");
else
pr_crit("watchdog cannot be disabled, system will reboot soon\n");
}
dw_wdt.expect_close = 0;
return 0;
}
#ifdef CONFIG_PM_SLEEP
static int dw_wdt_suspend(struct device *dev)
{
clk_disable_unprepare(dw_wdt.clk);
return 0;
}
static int dw_wdt_resume(struct device *dev)
{
int err = clk_prepare_enable(dw_wdt.clk);
if (err)
return err;
dw_wdt_keepalive();
return 0;
}
#endif /* CONFIG_PM_SLEEP */
static SIMPLE_DEV_PM_OPS(dw_wdt_pm_ops, dw_wdt_suspend, dw_wdt_resume);
static const struct file_operations wdt_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
.open = dw_wdt_open,
.write = dw_wdt_write,
.unlocked_ioctl = dw_wdt_ioctl,
.release = dw_wdt_release
};
static struct miscdevice dw_wdt_miscdev = {
.fops = &wdt_fops,
.name = "watchdog",
.minor = WATCHDOG_MINOR,
};
static int dw_wdt_drv_probe(struct platform_device *pdev)
{
int ret;
struct resource *mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!mem)
return -EINVAL;
dw_wdt.regs = devm_ioremap_resource(&pdev->dev, mem);
if (IS_ERR(dw_wdt.regs))
return PTR_ERR(dw_wdt.regs);
dw_wdt.clk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(dw_wdt.clk))
return PTR_ERR(dw_wdt.clk);
ret = clk_prepare_enable(dw_wdt.clk);
if (ret)
return ret;
spin_lock_init(&dw_wdt.lock);
ret = misc_register(&dw_wdt_miscdev);
if (ret)
goto out_disable_clk;
dw_wdt_set_next_heartbeat();
setup_timer(&dw_wdt.timer, dw_wdt_ping, 0);
mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);
return 0;
out_disable_clk:
clk_disable_unprepare(dw_wdt.clk);
return ret;
}
static int dw_wdt_drv_remove(struct platform_device *pdev)
{
misc_deregister(&dw_wdt_miscdev);
clk_disable_unprepare(dw_wdt.clk);
return 0;
}
#ifdef CONFIG_OF
static const struct of_device_id dw_wdt_of_match[] = {
{ .compatible = "snps,dw-wdt", },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, dw_wdt_of_match);
#endif
static struct platform_driver dw_wdt_driver = {
.probe = dw_wdt_drv_probe,
.remove = dw_wdt_drv_remove,
.driver = {
.name = "dw_wdt",
.owner = THIS_MODULE,
.of_match_table = of_match_ptr(dw_wdt_of_match),
.pm = &dw_wdt_pm_ops,
},
};
module_platform_driver(dw_wdt_driver);
MODULE_AUTHOR("Jamie Iles");
MODULE_DESCRIPTION("Synopsys DesignWare Watchdog Driver");
MODULE_LICENSE("GPL");
