[PATCH 3/8] [WATCHDOG] mpc83xx_wdt: add support for MPC86xx CPUs

Anton Vorontsov
2008-06-02T17:39:33Z

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>
---
drivers/watchdog/Kconfig | 4 +-
drivers/watchdog/mpc83xx_wdt.c | 80 ++++++++++++++++++++++++++++++++++++----
2 files changed, 74 insertions(+), 10 deletions(-)

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 254d115..2929055 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -683,8 +683,8 @@ 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"
diff --git a/drivers/watchdog/mpc83xx_wdt.c b/drivers/watchdog/mpc83xx_wdt.c
index 127d85e..19e3082 100644
--- a/drivers/watchdog/mpc83xx_wdt.c
+++ b/drivers/watchdog/mpc83xx_wdt.c
@@ -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.
@@ -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)
{
@@ -85,7 +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)
@@ -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 @@ err_unmap:

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);
--
1.5.5.1