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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (c) 2009 Nuvoton technology corporation.
*
* Wan ZongShun <mcuos.com@gmail.com>
*/
#include <linux/bitops.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/io.h>
#include <linux/clk.h>
#include <linux/kernel.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/types.h>
#include <linux/watchdog.h>
#include <linux/uaccess.h>
#define REG_WTCR 0x1c
#define WTCLK (0x01 << 10)
#define WTE (0x01 << 7) /*wdt enable*/
#define WTIS (0x03 << 4)
#define WTIF (0x01 << 3)
#define WTRF (0x01 << 2)
#define WTRE (0x01 << 1)
#define WTR (0x01 << 0)
/*
* The watchdog time interval can be calculated via following formula:
* WTIS real time interval (formula)
* 0x00 ((2^ 14 ) * ((external crystal freq) / 256))seconds
* 0x01 ((2^ 16 ) * ((external crystal freq) / 256))seconds
* 0x02 ((2^ 18 ) * ((external crystal freq) / 256))seconds
* 0x03 ((2^ 20 ) * ((external crystal freq) / 256))seconds
*
* The external crystal freq is 15Mhz in the nuc900 evaluation board.
* So 0x00 = +-0.28 seconds, 0x01 = +-1.12 seconds, 0x02 = +-4.48 seconds,
* 0x03 = +- 16.92 seconds..
*/
#define WDT_HW_TIMEOUT 0x02
#define WDT_TIMEOUT (HZ/2)
#define WDT_HEARTBEAT 15
static int heartbeat = WDT_HEARTBEAT;
module_param(heartbeat, int, 0);
MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. "
"(default = " __MODULE_STRING(WDT_HEARTBEAT) ")");
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) ")");
struct nuc900_wdt {
struct clk *wdt_clock;
struct platform_device *pdev;
void __iomem *wdt_base;
char expect_close;
struct timer_list timer;
spinlock_t wdt_lock;
unsigned long next_heartbeat;
};
static unsigned long nuc900wdt_busy;
static struct nuc900_wdt *nuc900_wdt;
static inline void nuc900_wdt_keepalive(void)
{
unsigned int val;
spin_lock(&nuc900_wdt->wdt_lock);
val = __raw_readl(nuc900_wdt->wdt_base + REG_WTCR);
val |= (WTR | WTIF);
__raw_writel(val, nuc900_wdt->wdt_base + REG_WTCR);
spin_unlock(&nuc900_wdt->wdt_lock);
}
static inline void nuc900_wdt_start(void)
{
unsigned int val;
spin_lock(&nuc900_wdt->wdt_lock);
val = __raw_readl(nuc900_wdt->wdt_base + REG_WTCR);
val |= (WTRE | WTE | WTR | WTCLK | WTIF);
val &= ~WTIS;
val |= (WDT_HW_TIMEOUT << 0x04);
__raw_writel(val, nuc900_wdt->wdt_base + REG_WTCR);
spin_unlock(&nuc900_wdt->wdt_lock);
nuc900_wdt->next_heartbeat = jiffies + heartbeat * HZ;
mod_timer(&nuc900_wdt->timer, jiffies + WDT_TIMEOUT);
}
static inline void nuc900_wdt_stop(void)
{
unsigned int val;
del_timer(&nuc900_wdt->timer);
spin_lock(&nuc900_wdt->wdt_lock);
val = __raw_readl(nuc900_wdt->wdt_base + REG_WTCR);
val &= ~WTE;
__raw_writel(val, nuc900_wdt->wdt_base + REG_WTCR);
spin_unlock(&nuc900_wdt->wdt_lock);
}
static inline void nuc900_wdt_ping(void)
{
nuc900_wdt->next_heartbeat = jiffies + heartbeat * HZ;
}
static int nuc900_wdt_open(struct inode *inode, struct file *file)
{
if (test_and_set_bit(0, &nuc900wdt_busy))
return -EBUSY;
nuc900_wdt_start();
return stream_open(inode, file);
}
static int nuc900_wdt_close(struct inode *inode, struct file *file)
{
if (nuc900_wdt->expect_close == 42)
nuc900_wdt_stop();
else {
dev_crit(&nuc900_wdt->pdev->dev,
"Unexpected close, not stopping watchdog!\n");
nuc900_wdt_ping();
}
nuc900_wdt->expect_close = 0;
clear_bit(0, &nuc900wdt_busy);
return 0;
}
static const struct watchdog_info nuc900_wdt_info = {
.identity = "nuc900 watchdog",
.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
WDIOF_MAGICCLOSE,
};
static long nuc900_wdt_ioctl(struct file *file,
unsigned int cmd, unsigned long arg)
{
void __user *argp = (void __user *)arg;
int __user *p = argp;
int new_value;
switch (cmd) {
case WDIOC_GETSUPPORT:
return copy_to_user(argp, &nuc900_wdt_info,
sizeof(nuc900_wdt_info)) ? -EFAULT : 0;
case WDIOC_GETSTATUS:
case WDIOC_GETBOOTSTATUS:
return put_user(0, p);
case WDIOC_KEEPALIVE:
nuc900_wdt_ping();
return 0;
case WDIOC_SETTIMEOUT:
if (get_user(new_value, p))
return -EFAULT;
heartbeat = new_value;
nuc900_wdt_ping();
return put_user(new_value, p);
case WDIOC_GETTIMEOUT:
return put_user(heartbeat, p);
default:
return -ENOTTY;
}
}
static ssize_t nuc900_wdt_write(struct file *file, const char __user *data,
size_t len, loff_t *ppos)
{
if (!len)
return 0;
/* Scan for magic character */
if (!nowayout) {
size_t i;
nuc900_wdt->expect_close = 0;
for (i = 0; i < len; i++) {
char c;
if (get_user(c, data + i))
return -EFAULT;
if (c == 'V') {
nuc900_wdt->expect_close = 42;
break;
}
}
}
nuc900_wdt_ping();
return len;
}
static void nuc900_wdt_timer_ping(struct timer_list *unused)
{
if (time_before(jiffies, nuc900_wdt->next_heartbeat)) {
nuc900_wdt_keepalive();
mod_timer(&nuc900_wdt->timer, jiffies + WDT_TIMEOUT);
} else
dev_warn(&nuc900_wdt->pdev->dev, "Will reset the machine !\n");
}
static const struct file_operations nuc900wdt_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
.unlocked_ioctl = nuc900_wdt_ioctl,
.open = nuc900_wdt_open,
.release = nuc900_wdt_close,
.write = nuc900_wdt_write,
};
static struct miscdevice nuc900wdt_miscdev = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &nuc900wdt_fops,
};
static int nuc900wdt_probe(struct platform_device *pdev)
{
int ret = 0;
nuc900_wdt = devm_kzalloc(&pdev->dev, sizeof(*nuc900_wdt),
GFP_KERNEL);
if (!nuc900_wdt)
return -ENOMEM;
nuc900_wdt->pdev = pdev;
spin_lock_init(&nuc900_wdt->wdt_lock);
nuc900_wdt->wdt_base = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(nuc900_wdt->wdt_base))
return PTR_ERR(nuc900_wdt->wdt_base);
nuc900_wdt->wdt_clock = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(nuc900_wdt->wdt_clock)) {
dev_err(&pdev->dev, "failed to find watchdog clock source\n");
return PTR_ERR(nuc900_wdt->wdt_clock);
}
clk_enable(nuc900_wdt->wdt_clock);
timer_setup(&nuc900_wdt->timer, nuc900_wdt_timer_ping, 0);
ret = misc_register(&nuc900wdt_miscdev);
if (ret) {
dev_err(&pdev->dev, "err register miscdev on minor=%d (%d)\n",
WATCHDOG_MINOR, ret);
goto err_clk;
}
return 0;
err_clk:
clk_disable(nuc900_wdt->wdt_clock);
return ret;
}
static int nuc900wdt_remove(struct platform_device *pdev)
{
misc_deregister(&nuc900wdt_miscdev);
clk_disable(nuc900_wdt->wdt_clock);
return 0;
}
static struct platform_driver nuc900wdt_driver = {
.probe = nuc900wdt_probe,
.remove = nuc900wdt_remove,
.driver = {
.name = "nuc900-wdt",
},
};
module_platform_driver(nuc900wdt_driver);
MODULE_AUTHOR("Wan ZongShun <mcuos.com@gmail.com>");
MODULE_DESCRIPTION("Watchdog driver for NUC900");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:nuc900-wdt");
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