mpc8xxx_wdt.c 7.9 KB
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/*
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 * mpc8xxx_wdt.c - MPC8xx/MPC83xx/MPC86xx watchdog userspace interface
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 *
 * Authors: Dave Updegraff <dave@cray.org>
 * 	    Kumar Gala <galak@kernel.crashing.org>
 * 		Attribution: from 83xx_wst: Florian Schirmer <jolt@tuxbox.org>
 * 				..and from sc520_wdt
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 * Copyright (c) 2008  MontaVista Software, Inc.
 *                     Anton Vorontsov <avorontsov@ru.mvista.com>
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 *
 * Note: it appears that you can only actually ENABLE or DISABLE the thing
 * once after POR. Once enabled, you cannot disable, and vice versa.
 *
 * 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.
 */

#include <linux/fs.h>
#include <linux/init.h>
#include <linux/kernel.h>
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#include <linux/timer.h>
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#include <linux/miscdevice.h>
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#include <linux/of_platform.h>
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#include <linux/module.h>
#include <linux/watchdog.h>
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#include <linux/io.h>
#include <linux/uaccess.h>
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#include <sysdev/fsl_soc.h>
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struct mpc8xxx_wdt {
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	__be32 res0;
	__be32 swcrr; /* System watchdog control register */
#define SWCRR_SWTC 0xFFFF0000 /* Software Watchdog Time Count. */
#define SWCRR_SWEN 0x00000004 /* Watchdog Enable bit. */
#define SWCRR_SWRI 0x00000002 /* Software Watchdog Reset/Interrupt Select bit.*/
#define SWCRR_SWPR 0x00000001 /* Software Watchdog Counter Prescale bit. */
	__be32 swcnr; /* System watchdog count register */
	u8 res1[2];
	__be16 swsrr; /* System watchdog service register */
	u8 res2[0xF0];
};

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struct mpc8xxx_wdt_type {
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	int prescaler;
	bool hw_enabled;
};

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static struct mpc8xxx_wdt __iomem *wd_base;
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static int mpc8xxx_wdt_init_late(void);
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static u16 timeout = 0xffff;
module_param(timeout, ushort, 0);
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MODULE_PARM_DESC(timeout,
	"Watchdog timeout in ticks. (0<timeout<65536, default=65535");
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static int reset = 1;
module_param(reset, bool, 0);
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MODULE_PARM_DESC(reset,
	"Watchdog Interrupt/Reset Mode. 0 = interrupt, 1 = reset");
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static int nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, int, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
		 "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

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/*
 * We always prescale, but if someone really doesn't want to they can set this
 * to 0
 */
static int prescale = 1;
static unsigned int timeout_sec;

static unsigned long wdt_is_open;
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static DEFINE_SPINLOCK(wdt_spinlock);
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static void mpc8xxx_wdt_keepalive(void)
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{
	/* Ping the WDT */
	spin_lock(&wdt_spinlock);
	out_be16(&wd_base->swsrr, 0x556c);
	out_be16(&wd_base->swsrr, 0xaa39);
	spin_unlock(&wdt_spinlock);
}

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static void mpc8xxx_wdt_timer_ping(unsigned long arg);
static DEFINE_TIMER(wdt_timer, mpc8xxx_wdt_timer_ping, 0, 0);
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static void mpc8xxx_wdt_timer_ping(unsigned long arg)
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{
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	mpc8xxx_wdt_keepalive();
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	/* We're pinging it twice faster than needed, just to be sure. */
	mod_timer(&wdt_timer, jiffies + HZ * timeout_sec / 2);
}

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static void mpc8xxx_wdt_pr_warn(const char *msg)
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{
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	pr_crit("mpc8xxx_wdt: %s, expect the %s soon!\n", msg,
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		reset ? "reset" : "machine check exception");
}

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static ssize_t mpc8xxx_wdt_write(struct file *file, const char __user *buf,
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				 size_t count, loff_t *ppos)
{
	if (count)
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		mpc8xxx_wdt_keepalive();
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	return count;
}

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static int mpc8xxx_wdt_open(struct inode *inode, struct file *file)
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{
	u32 tmp = SWCRR_SWEN;
	if (test_and_set_bit(0, &wdt_is_open))
		return -EBUSY;

	/* Once we start the watchdog we can't stop it */
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	if (nowayout)
		__module_get(THIS_MODULE);
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	/* Good, fire up the show */
	if (prescale)
		tmp |= SWCRR_SWPR;
	if (reset)
		tmp |= SWCRR_SWRI;

	tmp |= timeout << 16;

	out_be32(&wd_base->swcrr, tmp);

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	del_timer_sync(&wdt_timer);

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	return nonseekable_open(inode, file);
}

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static int mpc8xxx_wdt_release(struct inode *inode, struct file *file)
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{
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	if (!nowayout)
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		mpc8xxx_wdt_timer_ping(0);
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	else
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		mpc8xxx_wdt_pr_warn("watchdog closed");
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	clear_bit(0, &wdt_is_open);
	return 0;
}

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static long mpc8xxx_wdt_ioctl(struct file *file, unsigned int cmd,
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							unsigned long arg)
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{
	void __user *argp = (void __user *)arg;
	int __user *p = argp;
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	static const struct watchdog_info ident = {
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		.options = WDIOF_KEEPALIVEPING,
		.firmware_version = 1,
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		.identity = "MPC8xxx",
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	};

	switch (cmd) {
	case WDIOC_GETSUPPORT:
		return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
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	case WDIOC_GETSTATUS:
	case WDIOC_GETBOOTSTATUS:
		return put_user(0, p);
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	case WDIOC_KEEPALIVE:
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		mpc8xxx_wdt_keepalive();
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		return 0;
	case WDIOC_GETTIMEOUT:
		return put_user(timeout_sec, p);
	default:
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		return -ENOTTY;
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	}
}

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static const struct file_operations mpc8xxx_wdt_fops = {
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	.owner		= THIS_MODULE,
	.llseek		= no_llseek,
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	.write		= mpc8xxx_wdt_write,
	.unlocked_ioctl	= mpc8xxx_wdt_ioctl,
	.open		= mpc8xxx_wdt_open,
	.release	= mpc8xxx_wdt_release,
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};

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static struct miscdevice mpc8xxx_wdt_miscdev = {
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	.minor	= WATCHDOG_MINOR,
	.name	= "watchdog",
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	.fops	= &mpc8xxx_wdt_fops,
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};

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static int __devinit mpc8xxx_wdt_probe(struct of_device *ofdev,
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				       const struct of_device_id *match)
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{
	int ret;
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	struct device_node *np = ofdev->node;
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	struct mpc8xxx_wdt_type *wdt_type = match->data;
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	u32 freq = fsl_get_sys_freq();
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	bool enabled;
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	if (!freq || freq == -1)
		return -EINVAL;
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	wd_base = of_iomap(np, 0);
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	if (!wd_base)
		return -ENOMEM;
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	enabled = in_be32(&wd_base->swcrr) & SWCRR_SWEN;
	if (!enabled && wdt_type->hw_enabled) {
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		pr_info("mpc8xxx_wdt: could not be enabled in software\n");
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		ret = -ENOSYS;
		goto err_unmap;
	}

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	/* Calculate the timeout in seconds */
	if (prescale)
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		timeout_sec = (timeout * wdt_type->prescaler) / freq;
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	else
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		timeout_sec = timeout / freq;
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#ifdef MODULE
	ret = mpc8xxx_wdt_init_late();
	if (ret)
		goto err_unmap;
#endif

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	pr_info("WDT driver for MPC8xxx initialized. mode:%s timeout=%d "
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		"(%d seconds)\n", reset ? "reset" : "interrupt", timeout,
		timeout_sec);
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	/*
	 * If the watchdog was previously enabled or we're running on
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	 * MPC8xxx, we should ping the wdt from the kernel until the
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	 * userspace handles it.
	 */
	if (enabled)
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		mpc8xxx_wdt_timer_ping(0);
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	return 0;
err_unmap:
	iounmap(wd_base);
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	wd_base = NULL;
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	return ret;
}

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static int __devexit mpc8xxx_wdt_remove(struct of_device *ofdev)
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{
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	mpc8xxx_wdt_pr_warn("watchdog removed");
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	del_timer_sync(&wdt_timer);
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	misc_deregister(&mpc8xxx_wdt_miscdev);
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	iounmap(wd_base);

	return 0;
}

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static const struct of_device_id mpc8xxx_wdt_match[] = {
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	{
		.compatible = "mpc83xx_wdt",
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		.data = &(struct mpc8xxx_wdt_type) {
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			.prescaler = 0x10000,
		},
	},
	{
		.compatible = "fsl,mpc8610-wdt",
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		.data = &(struct mpc8xxx_wdt_type) {
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			.prescaler = 0x10000,
			.hw_enabled = true,
		},
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	},
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	{
		.compatible = "fsl,mpc823-wdt",
		.data = &(struct mpc8xxx_wdt_type) {
			.prescaler = 0x800,
		},
	},
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	{},
};
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MODULE_DEVICE_TABLE(of, mpc8xxx_wdt_match);
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static struct of_platform_driver mpc8xxx_wdt_driver = {
	.match_table	= mpc8xxx_wdt_match,
	.probe		= mpc8xxx_wdt_probe,
	.remove		= __devexit_p(mpc8xxx_wdt_remove),
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	.driver		= {
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		.name	= "mpc8xxx_wdt",
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		.owner	= THIS_MODULE,
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	},
};

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/*
 * We do wdt initialization in two steps: arch_initcall probes the wdt
 * very early to start pinging the watchdog (misc devices are not yet
 * available), and later module_init() just registers the misc device.
 */
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static int mpc8xxx_wdt_init_late(void)
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{
	int ret;

	if (!wd_base)
		return -ENODEV;

	ret = misc_register(&mpc8xxx_wdt_miscdev);
	if (ret) {
		pr_err("cannot register miscdev on minor=%d (err=%d)\n",
			WATCHDOG_MINOR, ret);
		return ret;
	}
	return 0;
}
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#ifndef MODULE
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module_init(mpc8xxx_wdt_init_late);
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#endif
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static int __init mpc8xxx_wdt_init(void)
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{
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	return of_register_platform_driver(&mpc8xxx_wdt_driver);
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}
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arch_initcall(mpc8xxx_wdt_init);
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static void __exit mpc8xxx_wdt_exit(void)
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{
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	of_unregister_platform_driver(&mpc8xxx_wdt_driver);
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}
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module_exit(mpc8xxx_wdt_exit);
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MODULE_AUTHOR("Dave Updegraff, Kumar Gala");
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MODULE_DESCRIPTION("Driver for watchdog timer in MPC8xx/MPC83xx/MPC86xx "
		   "uProcessors");
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MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
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