orion_wdt.c 6.83 KB
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/*
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 * drivers/watchdog/orion_wdt.c
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 *
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 * Watchdog driver for Orion/Kirkwood processors
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 *
 * Author: Sylver Bruneau <sylver.bruneau@googlemail.com>
 *
 * This file is licensed under  the terms of the GNU General Public
 * License version 2. This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 */

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
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#include <linux/platform_device.h>
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#include <linux/watchdog.h>
#include <linux/init.h>
#include <linux/uaccess.h>
#include <linux/io.h>
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#include <linux/spinlock.h>
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#include <mach/bridge-regs.h>
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#include <plat/orion_wdt.h>
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/*
 * Watchdog timer block registers.
 */
#define TIMER_CTRL		(TIMER_VIRT_BASE + 0x0000)
#define  WDT_EN			0x0010
#define WDT_VAL			(TIMER_VIRT_BASE + 0x0024)

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#define WDT_MAX_CYCLE_COUNT	0xffffffff
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#define WDT_IN_USE		0
#define WDT_OK_TO_CLOSE		1

static int nowayout = WATCHDOG_NOWAYOUT;
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static int heartbeat = -1;		/* module parameter (seconds) */
static unsigned int wdt_max_duration;	/* (seconds) */
static unsigned int wdt_tclk;
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static unsigned long wdt_status;
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static spinlock_t wdt_lock;
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static void orion_wdt_ping(void)
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{
	spin_lock(&wdt_lock);

	/* Reload watchdog duration */
	writel(wdt_tclk * heartbeat, WDT_VAL);

	spin_unlock(&wdt_lock);
}

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static void orion_wdt_enable(void)
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{
	u32 reg;

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	spin_lock(&wdt_lock);

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	/* Set watchdog duration */
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	writel(wdt_tclk * heartbeat, WDT_VAL);
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	/* Clear watchdog timer interrupt */
	reg = readl(BRIDGE_CAUSE);
	reg &= ~WDT_INT_REQ;
	writel(reg, BRIDGE_CAUSE);

	/* Enable watchdog timer */
	reg = readl(TIMER_CTRL);
	reg |= WDT_EN;
	writel(reg, TIMER_CTRL);

	/* Enable reset on watchdog */
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	reg = readl(RSTOUTn_MASK);
	reg |= WDT_RESET_OUT_EN;
	writel(reg, RSTOUTn_MASK);
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	spin_unlock(&wdt_lock);
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}

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static void orion_wdt_disable(void)
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{
	u32 reg;

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	spin_lock(&wdt_lock);

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	/* Disable reset on watchdog */
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	reg = readl(RSTOUTn_MASK);
	reg &= ~WDT_RESET_OUT_EN;
	writel(reg, RSTOUTn_MASK);
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	/* Disable watchdog timer */
	reg = readl(TIMER_CTRL);
	reg &= ~WDT_EN;
	writel(reg, TIMER_CTRL);
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	spin_unlock(&wdt_lock);
}

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static int orion_wdt_get_timeleft(int *time_left)
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{
	spin_lock(&wdt_lock);
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	*time_left = readl(WDT_VAL) / wdt_tclk;
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	spin_unlock(&wdt_lock);
	return 0;
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}

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static int orion_wdt_open(struct inode *inode, struct file *file)
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{
	if (test_and_set_bit(WDT_IN_USE, &wdt_status))
		return -EBUSY;
	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
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	orion_wdt_enable();
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	return nonseekable_open(inode, file);
}

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static ssize_t orion_wdt_write(struct file *file, const char *data,
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					size_t len, loff_t *ppos)
{
	if (len) {
		if (!nowayout) {
			size_t i;

			clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
			for (i = 0; i != len; i++) {
				char c;

				if (get_user(c, data + i))
					return -EFAULT;
				if (c == 'V')
					set_bit(WDT_OK_TO_CLOSE, &wdt_status);
			}
		}
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		orion_wdt_ping();
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	}
	return len;
}

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static int orion_wdt_settimeout(int new_time)
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{
	if ((new_time <= 0) || (new_time > wdt_max_duration))
		return -EINVAL;

	/* Set new watchdog time to be used when
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	 * orion_wdt_enable() or orion_wdt_ping() is called. */
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	heartbeat = new_time;
	return 0;
}

static const struct watchdog_info ident = {
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	.options	= WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT |
			  WDIOF_KEEPALIVEPING,
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	.identity	= "Orion Watchdog",
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};

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static long orion_wdt_ioctl(struct file *file, unsigned int cmd,
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				unsigned long arg)
{
	int ret = -ENOTTY;
	int time;

	switch (cmd) {
	case WDIOC_GETSUPPORT:
		ret = copy_to_user((struct watchdog_info *)arg, &ident,
				   sizeof(ident)) ? -EFAULT : 0;
		break;

	case WDIOC_GETSTATUS:
	case WDIOC_GETBOOTSTATUS:
		ret = put_user(0, (int *)arg);
		break;

	case WDIOC_KEEPALIVE:
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		orion_wdt_ping();
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		ret = 0;
		break;

	case WDIOC_SETTIMEOUT:
		ret = get_user(time, (int *)arg);
		if (ret)
			break;

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		if (orion_wdt_settimeout(time)) {
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			ret = -EINVAL;
			break;
		}
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		orion_wdt_ping();
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		/* Fall through */

	case WDIOC_GETTIMEOUT:
		ret = put_user(heartbeat, (int *)arg);
		break;

	case WDIOC_GETTIMELEFT:
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		if (orion_wdt_get_timeleft(&time)) {
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			ret = -EINVAL;
			break;
		}
		ret = put_user(time, (int *)arg);
		break;
	}
	return ret;
}

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static int orion_wdt_release(struct inode *inode, struct file *file)
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{
	if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
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		orion_wdt_disable();
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	else
		printk(KERN_CRIT "WATCHDOG: Device closed unexpectedly - "
					"timer will not stop\n");
	clear_bit(WDT_IN_USE, &wdt_status);
	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);

	return 0;
}


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static const struct file_operations orion_wdt_fops = {
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	.owner		= THIS_MODULE,
	.llseek		= no_llseek,
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	.write		= orion_wdt_write,
	.unlocked_ioctl	= orion_wdt_ioctl,
	.open		= orion_wdt_open,
	.release	= orion_wdt_release,
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};

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static struct miscdevice orion_wdt_miscdev = {
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	.minor		= WATCHDOG_MINOR,
	.name		= "watchdog",
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	.fops		= &orion_wdt_fops,
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};

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static int __devinit orion_wdt_probe(struct platform_device *pdev)
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{
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	struct orion_wdt_platform_data *pdata = pdev->dev.platform_data;
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	int ret;

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	if (pdata) {
		wdt_tclk = pdata->tclk;
	} else {
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		printk(KERN_ERR "Orion Watchdog misses platform data\n");
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		return -ENODEV;
	}

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	if (orion_wdt_miscdev.parent)
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		return -EBUSY;
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	orion_wdt_miscdev.parent = &pdev->dev;
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	wdt_max_duration = WDT_MAX_CYCLE_COUNT / wdt_tclk;
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	if (orion_wdt_settimeout(heartbeat))
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		heartbeat = wdt_max_duration;
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	ret = misc_register(&orion_wdt_miscdev);
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	if (ret)
		return ret;

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	printk(KERN_INFO "Orion Watchdog Timer: Initial timeout %d sec%s\n",
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				heartbeat, nowayout ? ", nowayout" : "");
	return 0;
}

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static int __devexit orion_wdt_remove(struct platform_device *pdev)
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{
	int ret;

	if (test_bit(WDT_IN_USE, &wdt_status)) {
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		orion_wdt_disable();
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		clear_bit(WDT_IN_USE, &wdt_status);
	}

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	ret = misc_deregister(&orion_wdt_miscdev);
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	if (!ret)
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		orion_wdt_miscdev.parent = NULL;
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	return ret;
}

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static void orion_wdt_shutdown(struct platform_device *pdev)
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{
	if (test_bit(WDT_IN_USE, &wdt_status))
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		orion_wdt_disable();
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}

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static struct platform_driver orion_wdt_driver = {
	.probe		= orion_wdt_probe,
	.remove		= __devexit_p(orion_wdt_remove),
	.shutdown	= orion_wdt_shutdown,
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	.driver		= {
		.owner	= THIS_MODULE,
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		.name	= "orion_wdt",
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	},
};

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static int __init orion_wdt_init(void)
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{
	spin_lock_init(&wdt_lock);
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	return platform_driver_register(&orion_wdt_driver);
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}

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static void __exit orion_wdt_exit(void)
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{
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	platform_driver_unregister(&orion_wdt_driver);
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}

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module_init(orion_wdt_init);
module_exit(orion_wdt_exit);
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MODULE_AUTHOR("Sylver Bruneau <sylver.bruneau@googlemail.com>");
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MODULE_DESCRIPTION("Orion Processor Watchdog");
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module_param(heartbeat, int, 0);
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MODULE_PARM_DESC(heartbeat, "Initial watchdog heartbeat in seconds");
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module_param(nowayout, int, 0);
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MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
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MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);