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Commit 500c919e authored by Anton Vorontsov's avatar Anton Vorontsov Committed by Wim Van Sebroeck
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[WATCHDOG] mpc83xx_wdt: add support for MPC86xx CPUs 



On MPC86xx the watchdog could be enabled only at power-on-reset, and could
not be disabled afterwards.  We must ping the watchdog from the kernel
until the userspace handles it.

MPC83xx CPUs are only differ in a way that watchdog could be disabled
once, but after it was enabled via software it becomes just the same as
MPC86xx.

Thus, to support MPC86xx I added the kernel timer which pings the watchdog
until the userspace opens it.

Since we implemented the timer, now we're able to implement proper
handling for the CONFIG_WATCHDOG_NOWAYOUT case, for MPC83xx and MPC86xx.

Also move the probe code into subsys_initcall, because we want start
pinging the watchdog ASAP, and misc devices are available in
subsys_initcall.

Signed-off-by: default avatarAnton Vorontsov <avorontsov@ru.mvista.com>
Cc: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: default avatarWim Van Sebroeck <wim@iguana.be>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent ef8ab12e

drivers/watchdog/Kconfig

+2 −2
Original line number Diff line number Diff line
@@ -696,8 +696,8 @@ config 8xx_WDT 
	depends on 8xx



config 83xx_WDT

	tristate "MPC83xx Watchdog Timer"

	depends on PPC_83xx

	tristate "MPC83xx/MPC86xx Watchdog Timer"

	depends on PPC_83xx || PPC_86xx



config MV64X60_WDT

	tristate "MV64X60 (Marvell Discovery) Watchdog Timer"

drivers/watchdog/mpc83xx_wdt.c

+72 −8
Original line number Diff line number Diff line 
/*

 * mpc83xx_wdt.c - MPC83xx watchdog userspace interface

 * mpc83xx_wdt.c - MPC83xx/MPC86xx watchdog userspace interface

 *

 * 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

 * Copyright (c) 2008  MontaVista Software, Inc.

 *                     Anton Vorontsov <avorontsov@ru.mvista.com>

 *

 * Note: it appears that you can only actually ENABLE or DISABLE the thing

 * once after POR. Once enabled, you cannot disable, and vice versa.
@@ -18,6 +20,7 @@ 
#include <linux/fs.h>

#include <linux/init.h>

#include <linux/kernel.h>

#include <linux/timer.h>

#include <linux/miscdevice.h>

#include <linux/of_platform.h>

#include <linux/module.h>
@@ -39,6 +42,11 @@ struct mpc83xx_wdt { 
	u8 res2[0xF0];

};



struct mpc83xx_wdt_type {

	int prescaler;

	bool hw_enabled;

};



static struct mpc83xx_wdt __iomem *wd_base;



static u16 timeout = 0xffff;
@@ -51,6 +59,11 @@ module_param(reset, bool, 0); 
MODULE_PARM_DESC(reset,

	"Watchdog Interrupt/Reset Mode. 0 = interrupt, 1 = reset");



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) ")");



/*

 * We always prescale, but if someone really doesn't want to they can set this

 * to 0
@@ -70,6 +83,22 @@ static void mpc83xx_wdt_keepalive(void) 
	spin_unlock(&wdt_spinlock);

}



static void mpc83xx_wdt_timer_ping(unsigned long arg);

static DEFINE_TIMER(wdt_timer, mpc83xx_wdt_timer_ping, 0, 0);



static void mpc83xx_wdt_timer_ping(unsigned long arg)

{

	mpc83xx_wdt_keepalive();

	/* We're pinging it twice faster than needed, just to be sure. */

	mod_timer(&wdt_timer, jiffies + HZ * timeout_sec / 2);

}



static void mpc83xx_wdt_pr_warn(const char *msg)

{

	pr_crit("mpc83xx_wdt: %s, expect the %s soon!\n", msg,

		reset ? "reset" : "machine check exception");

}



static ssize_t mpc83xx_wdt_write(struct file *file, const char __user *buf,

				 size_t count, loff_t *ppos)

{
@@ -85,6 +114,7 @@ static int mpc83xx_wdt_open(struct inode *inode, struct file *file) 
		return -EBUSY;



	/* Once we start the watchdog we can't stop it */

	if (nowayout)

		__module_get(THIS_MODULE);



	/* Good, fire up the show */
@@ -97,13 +127,17 @@ static int mpc83xx_wdt_open(struct inode *inode, struct file *file) 


	out_be32(&wd_base->swcrr, tmp);



	del_timer_sync(&wdt_timer);



	return nonseekable_open(inode, file);

}



static int mpc83xx_wdt_release(struct inode *inode, struct file *file)

{

	printk(KERN_CRIT "Unexpected close, not stopping watchdog!\n");

	mpc83xx_wdt_keepalive();

	if (!nowayout)

		mpc83xx_wdt_timer_ping(0);

	else

		mpc83xx_wdt_pr_warn("watchdog closed");

	clear_bit(0, &wdt_is_open);

	return 0;

}
@@ -154,15 +188,25 @@ static int __devinit mpc83xx_wdt_probe(struct of_device *ofdev, 
				       const struct of_device_id *match)

{

	int ret;

	struct device_node *np = ofdev->node;

	struct mpc83xx_wdt_type *wdt_type = match->data;

	u32 freq = fsl_get_sys_freq();

	bool enabled;



	if (!freq || freq == -1)

		return -EINVAL;



	wd_base = of_iomap(ofdev->node, 0);

	wd_base = of_iomap(np, 0);

	if (!wd_base)

		return -ENOMEM;



	enabled = in_be32(&wd_base->swcrr) & SWCRR_SWEN;

	if (!enabled && wdt_type->hw_enabled) {

		pr_info("mpc83xx_wdt: could not be enabled in software\n");

		ret = -ENOSYS;

		goto err_unmap;

	}



	ret = misc_register(&mpc83xx_wdt_miscdev);

	if (ret) {

		pr_err("cannot register miscdev on minor=%d (err=%d)\n",
@@ -172,13 +216,21 @@ static int __devinit mpc83xx_wdt_probe(struct of_device *ofdev, 


	/* Calculate the timeout in seconds */

	if (prescale)

		timeout_sec = (timeout * 0x10000) / freq;

		timeout_sec = (timeout * wdt_type->prescaler) / freq;

	else

		timeout_sec = timeout / freq;



	pr_info("WDT driver for MPC83xx initialized. mode:%s timeout=%d "

		"(%d seconds)\n", reset ? "reset" : "interrupt", timeout,

		timeout_sec);



	/*

	 * If the watchdog was previously enabled or we're running on

	 * MPC86xx, we should ping the wdt from the kernel until the

	 * userspace handles it.

	 */

	if (enabled)

		mpc83xx_wdt_timer_ping(0);

	return 0;

err_unmap:

	iounmap(wd_base);
@@ -187,6 +239,8 @@ static int __devinit mpc83xx_wdt_probe(struct of_device *ofdev, 


static int __devexit mpc83xx_wdt_remove(struct of_device *ofdev)

{

	mpc83xx_wdt_pr_warn("watchdog removed");

	del_timer_sync(&wdt_timer);

	misc_deregister(&mpc83xx_wdt_miscdev);

	iounmap(wd_base);
@@ -196,6 +250,16 @@ static int __devexit mpc83xx_wdt_remove(struct of_device *ofdev) 
static const struct of_device_id mpc83xx_wdt_match[] = {

	{

		.compatible = "mpc83xx_wdt",

		.data = &(struct mpc83xx_wdt_type) {

			.prescaler = 0x10000,

		},

	},

	{

		.compatible = "fsl,mpc8610-wdt",

		.data = &(struct mpc83xx_wdt_type) {

			.prescaler = 0x10000,

			.hw_enabled = true,

		},

	},

	{},

};
@@ -221,10 +285,10 @@ static void __exit mpc83xx_wdt_exit(void) 
	of_unregister_platform_driver(&mpc83xx_wdt_driver);

}



module_init(mpc83xx_wdt_init);

subsys_initcall(mpc83xx_wdt_init);

module_exit(mpc83xx_wdt_exit);



MODULE_AUTHOR("Dave Updegraff, Kumar Gala");

MODULE_DESCRIPTION("Driver for watchdog timer in MPC83xx uProcessor");

MODULE_DESCRIPTION("Driver for watchdog timer in MPC83xx/MPC86xx uProcessors");

MODULE_LICENSE("GPL");

MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);