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[WATCHDOG] mpc83xx_wdt: add support for MPC86xx CPUs
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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: Anton Vorontsov <avorontsov@ru.mvista.com>
Cc: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Anton Vorontsov authored and Wim Van Sebroeck committed Aug 6, 2008
1 parent ef8ab12 commit 500c919
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Showing 2 changed files with 74 additions and 10 deletions.
4 changes: 2 additions & 2 deletions drivers/watchdog/Kconfig
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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"
Expand Down
80 changes: 72 additions & 8 deletions drivers/watchdog/mpc83xx_wdt.c
View file
Original file line number Diff line number Diff line change
@@ -1,10 +1,12 @@
/*
* 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.
Expand All @@ -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>
Expand All @@ -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;
Expand All @@ -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
Expand All @@ -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)
{
Expand All @@ -85,7 +114,8 @@ static int mpc83xx_wdt_open(struct inode *inode, struct file *file)
return -EBUSY;

/* Once we start the watchdog we can't stop it */
__module_get(THIS_MODULE);
if (nowayout)
__module_get(THIS_MODULE);

/* Good, fire up the show */
if (prescale)
Expand All @@ -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;
}
Expand Down Expand Up @@ -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",
Expand All @@ -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);
Expand All @@ -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);

Expand All @@ -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,
},
},
{},
};
Expand All @@ -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);

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