/*
* Watchdog driver for Atmel AT32AP700X devices
*
* Copyright (C) 2005-2006 Atmel Corporation
*
* 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.
*
*
* Errata: WDT Clear is blocked after WDT Reset
*
* A watchdog timer event will, after reset, block writes to the WDT_CLEAR
* register, preventing the program to clear the next Watchdog Timer Reset.
*
* If you still want to use the WDT after a WDT reset a small code can be
* insterted at the startup checking the AVR32_PM.rcause register for WDT reset
* and use a GPIO pin to reset the system. This method requires that one of the
* GPIO pins are available and connected externally to the RESET_N pin. After
* the GPIO pin has pulled down the reset line the GPIO will be reset and leave
* the pin tristated with pullup.
*/
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/miscdevice.h>
#include <linux/fs.h>
#include <linux/platform_device.h>
#include <linux/watchdog.h>
#include <linux/uaccess.h>
#include <linux/io.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
#define TIMEOUT_MIN 1
#define TIMEOUT_MAX 2
#define TIMEOUT_DEFAULT TIMEOUT_MAX
/* module parameters */
static int timeout = TIMEOUT_DEFAULT;
module_param(timeout, int, 0);
MODULE_PARM_DESC(timeout,
"Timeout value. Limited to be 1 or 2 seconds. (default="
__MODULE_STRING(TIMEOUT_DEFAULT) ")");
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) ")");
/* Watchdog registers and write/read macro */
#define WDT_CTRL 0x00
#define WDT_CTRL_EN 0
#define WDT_CTRL_PSEL 8
#define WDT_CTRL_KEY 24
#define WDT_CLR 0x04
#define WDT_RCAUSE 0x10
#define WDT_RCAUSE_POR 0
#define WDT_RCAUSE_EXT 2
#define WDT_RCAUSE_WDT 3
#define WDT_RCAUSE_JTAG 4
#define WDT_RCAUSE_SERP 5
#define WDT_BIT(name) (1 << WDT_##name)
#define WDT_BF(name, value) ((value) << WDT_##name)
#define wdt_readl(dev, reg) \
__raw_readl((dev)->regs + WDT_##reg)
#define wdt_writel(dev, reg, value) \
__raw_writel((value), (dev)->regs + WDT_##reg)
struct wdt_at32ap700x {
void __iomem *regs;
spinlock_t io_lock;
int timeout;
int boot_status;
unsigned long users;
struct miscdevice miscdev;
};
static struct wdt_at32ap700x *wdt;
static char expect_release;
/*
* Disable the watchdog.
*/
static inline void at32_wdt_stop(void)
{
unsigned long psel;
spin_lock(&wdt->io_lock);
psel = wdt_readl(wdt, CTRL) & WDT_BF(CTRL_PSEL, 0x0f);
wdt_writel(wdt, CTRL, psel | WDT_BF(CTRL_KEY, 0x55));
wdt_writel(wdt, CTRL, psel | WDT_BF(CTRL_KEY, 0xaa));
spin_unlock(&wdt->io_lock);
}
/*
* Enable and reset the watchdog.
*/
static inline void at32_wdt_start(void)
{
/* 0xf is 2^16 divider = 2 sec, 0xe is 2^15 divider = 1 sec */
unsigned long psel = (wdt->timeout > 1) ? 0xf : 0xe;
spin_lock(&wdt->io_lock);
wdt_writel(wdt, CTRL, WDT_BIT(CTRL_EN)
| WDT_BF(CTRL_PSEL, psel)
| WDT_BF(CTRL_KEY, 0x55));
wdt_writel(wdt, CTRL, WDT_BIT(CTRL_EN)
| WDT_BF(CTRL_PSEL, psel)
| WDT_BF(CTRL_KEY, 0xaa));
spin_unlock(&wdt->io_lock);
}
/*
* Pat the watchdog timer.
*/
static inline void at32_wdt_pat(void)
{
spin_lock(&wdt->io_lock);
wdt_writel(wdt, CLR, 0x42);
spin_unlock(&wdt->io_lock);
}
/*
* Watchdog device is opened, and watchdog starts running.
*/
static int at32_wdt_open(struct inode *inode, struct file *file)
{
if (test_and_set_bit(1, &wdt->users))
return -EBUSY;
at32_wdt_start();
return nonseekable_open(inode, file);
}
/*
* Close the watchdog device.
*/
static int at32_wdt_close(struct inode *inode, struct file *file)
{
if (expect_release == 42) {
at32_wdt_stop();
} else {
dev_dbg(wdt->miscdev.parent,
"unexpected close, not stopping watchdog!\n");
at32_wdt_pat();
}
clear_bit(1, &wdt->users);
expect_release = 0;
return 0;
}
/*
* Change the watchdog time interval.
*/
static int at32_wdt_settimeout(int time)
{
/*
* All counting occurs at 1 / SLOW_CLOCK (32 kHz) and max prescaler is
* 2 ^ 16 allowing up to 2 seconds timeout.
*/
if ((time < TIMEOUT_MIN) || (time > TIMEOUT_MAX))
return -EINVAL;
/*
* Set new watchdog time. It will be used when at32_wdt_start() is
* called.
*/
wdt->timeout = time;
return 0;
}
/*
* Get the watchdog status.
*/
static int at32_wdt_get_status(void)
{
int rcause;
int status = 0;
rcause = wdt_readl(wdt, RCAUSE);
switch (rcause) {
case WDT_BIT(RCAUSE_EXT):
status = WDIOF_EXTERN1;
break;
case WDT_BIT(RCAUSE_WDT):
status = WDIOF_CARDRESET;
break;
case WDT_BIT(RCAUSE_POR): /* fall through */
case WDT_BIT(RCAUSE_JTAG): /* fall through */
case WDT_BIT(RCAUSE_SERP): /* fall through */
default:
break;
}
return status;
}
static const struct watchdog_info at32_wdt_info = {
.identity = "at32ap700x watchdog",
.options = WDIOF_SETTIMEOUT |
WDIOF_KEEPALIVEPING |
WDIOF_MAGICCLOSE,
};
/*
* Handle commands from user-space.
*/
static long at32_wdt_ioctl(struct file *file,
unsigned int cmd, unsigned long arg)
{
int ret = -ENOTTY;
int time;
void __user *argp = (void __user *)arg;
int __user *p = argp;
switch (cmd) {
case WDIOC_GETSUPPORT:
ret = copy_to_user(argp, &at32_wdt_info,
sizeof(at32_wdt_info)) ? -EFAULT : 0;
break;
case WDIOC_GETSTATUS:
ret = put_user(0, p);
break;
case WDIOC_GETBOOTSTATUS:
ret = put_user(wdt->boot_status, p);
break;
case WDIOC_SETOPTIONS:
ret = get_user(time, p);
if (ret)
break;
if (time & WDIOS_DISABLECARD)
at32_wdt_stop();
if (time & WDIOS_ENABLECARD)
at32_wdt_start();
ret = 0;
break;
case WDIOC_KEEPALIVE:
at32_wdt_pat();
ret = 0;
break;
case WDIOC_SETTIMEOUT:
ret = get_user(time, p);
if (ret)
break;
ret = at32_wdt_settimeout(time);
if (ret)
break;
/* Enable new time value */
at32_wdt_start();
/* fall through */
case WDIOC_GETTIMEOUT:
ret = put_user(wdt->timeout, p);
break;
}
return ret;
}
static ssize_t at32_wdt_write(struct file *file, const char __user *data,
size_t len, loff_t *ppos)
{
/* See if we got the magic character 'V' and reload the timer */
if (len) {
if (!nowayout) {
size_t i;
/*
* note: just in case someone wrote the magic
* character five months ago...
*/
expect_release = 0;
/*
* scan to see whether or not we got the magic
* character
*/
for (i = 0; i != len; i++) {
char c;
if (get_user(c, data + i))
return -EFAULT;
if (c == 'V')
expect_release = 42;
}
}
/* someone wrote to us, we should pat the watchdog */
at32_wdt_pat();
}
return len;
}
static const struct file_operations at32_wdt_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
.unlocked_ioctl = at32_wdt_ioctl,
.open = at32_wdt_open,
.release = at32_wdt_close,
.write = at32_wdt_write,
};
static int __init at32_wdt_probe(struct platform_device *pdev)
{
struct resource *regs;
int ret;
if (wdt) {
dev_dbg(&pdev->dev, "only 1 wdt instance supported.\n");
return -EBUSY;
}
regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!regs) {
dev_dbg(&pdev->dev, "missing mmio resource\n");
return -ENXIO;
}
wdt = devm_kzalloc(&pdev->dev, sizeof(struct wdt_at32ap700x),
GFP_KERNEL);
if (!wdt) {
dev_dbg(&pdev->dev, "no memory for wdt structure\n");
return -ENOMEM;
}
wdt->regs = devm_ioremap(&pdev->dev, regs->start, resource_size(regs));
if (!wdt->regs) {
ret = -ENOMEM;
dev_dbg(&pdev->dev, "could not map I/O memory\n");
goto err_free;
}
spin_lock_init(&wdt->io_lock);
wdt->boot_status = at32_wdt_get_status();
/* Work-around for watchdog silicon errata. */
if (wdt->boot_status & WDIOF_CARDRESET) {
dev_info(&pdev->dev, "CPU must be reset with external "
"reset or POR due to silicon errata.\n");
ret = -EIO;
goto err_free;
} else {
wdt->users = 0;
}
wdt->miscdev.minor = WATCHDOG_MINOR;
wdt->miscdev.name = "watchdog";
wdt->miscdev.fops = &at32_wdt_fops;
wdt->miscdev.parent = &pdev->dev;
platform_set_drvdata(pdev, wdt);
if (at32_wdt_settimeout(timeout)) {
at32_wdt_settimeout(TIMEOUT_DEFAULT);
dev_dbg(&pdev->dev,
"default timeout invalid, set to %d sec.\n",
TIMEOUT_DEFAULT);
}
ret = misc_register(&wdt->miscdev);
if (ret) {
dev_dbg(&pdev->dev, "failed to register wdt miscdev\n");
goto err_free;
}
dev_info(&pdev->dev,
"AT32AP700X WDT at 0x%p, timeout %d sec (nowayout=%d)\n",
wdt->regs, wdt->timeout, nowayout);
return 0;
err_free:
wdt = NULL;
return ret;
}
static int __exit at32_wdt_remove(struct platform_device *pdev)
{
if (wdt && platform_get_drvdata(pdev) == wdt) {
/* Stop the timer before we leave */
if (!nowayout)
at32_wdt_stop();
misc_deregister(&wdt->miscdev);
wdt = NULL;
}
return 0;
}
static void at32_wdt_shutdown(struct platform_device *pdev)
{
at32_wdt_stop();
}
#ifdef CONFIG_PM
static int at32_wdt_suspend(struct platform_device *pdev, pm_message_t message)
{
at32_wdt_stop();
return 0;
}
static int at32_wdt_resume(struct platform_device *pdev)
{
if (wdt->users)
at32_wdt_start();
return 0;
}
#else
#define at32_wdt_suspend NULL
#define at32_wdt_resume NULL
#endif
/* work with hotplug and coldplug */
MODULE_ALIAS("platform:at32_wdt");
static struct platform_driver at32_wdt_driver = {
.remove = __exit_p(at32_wdt_remove),
.suspend = at32_wdt_suspend,
.resume = at32_wdt_resume,
.driver = {
.name = "at32_wdt",
.owner = THIS_MODULE,
},
.shutdown = at32_wdt_shutdown,
};
module_platform_driver_probe(at32_wdt_driver, at32_wdt_probe);
MODULE_AUTHOR("Hans-Christian Egtvedt <egtvedt@samfundet.no>");
MODULE_DESCRIPTION("Watchdog driver for Atmel AT32AP700X");
MODULE_LICENSE("GPL");
