linux/drivers/watchdog/mpcore_wdt.c

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/*
* Watchdog driver for the mpcore watchdog timer
*
* (c) Copyright 2004 ARM Limited
*
* Based on the SoftDog driver:
* (c) Copyright 1996 Alan Cox <alan@redhat.com>, All Rights Reserved.
* http://www.redhat.com
*
* 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.
*
* Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
* warranty for any of this software. This material is provided
* "AS-IS" and at no charge.
*
* (c) Copyright 1995 Alan Cox <alan@lxorguk.ukuu.org.uk>
*
*/
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/fs.h>
#include <linux/reboot.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
#include <asm/hardware/arm_twd.h>
#include <asm/uaccess.h>
struct mpcore_wdt {
unsigned long timer_alive;
struct device *dev;
void __iomem *base;
int irq;
unsigned int perturb;
char expect_close;
};
static struct platform_device *mpcore_wdt_dev;
extern unsigned int mpcore_timer_rate;
#define TIMER_MARGIN 60
static int mpcore_margin = TIMER_MARGIN;
module_param(mpcore_margin, int, 0);
MODULE_PARM_DESC(mpcore_margin, "MPcore timer margin in seconds. (0<mpcore_margin<65536, default=" __MODULE_STRING(TIMER_MARGIN) ")");
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) ")");
#define ONLY_TESTING 0
static int mpcore_noboot = ONLY_TESTING;
module_param(mpcore_noboot, int, 0);
MODULE_PARM_DESC(mpcore_noboot, "MPcore watchdog action, set to 1 to ignore reboots, 0 to reboot (default=" __MODULE_STRING(ONLY_TESTING) ")");
/*
* This is the interrupt handler. Note that we only use this
* in testing mode, so don't actually do a reboot here.
*/
IRQ: Maintain regs pointer globally rather than passing to IRQ handlers Maintain a per-CPU global "struct pt_regs *" variable which can be used instead of passing regs around manually through all ~1800 interrupt handlers in the Linux kernel. The regs pointer is used in few places, but it potentially costs both stack space and code to pass it around. On the FRV arch, removing the regs parameter from all the genirq function results in a 20% speed up of the IRQ exit path (ie: from leaving timer_interrupt() to leaving do_IRQ()). Where appropriate, an arch may override the generic storage facility and do something different with the variable. On FRV, for instance, the address is maintained in GR28 at all times inside the kernel as part of general exception handling. Having looked over the code, it appears that the parameter may be handed down through up to twenty or so layers of functions. Consider a USB character device attached to a USB hub, attached to a USB controller that posts its interrupts through a cascaded auxiliary interrupt controller. A character device driver may want to pass regs to the sysrq handler through the input layer which adds another few layers of parameter passing. I've build this code with allyesconfig for x86_64 and i386. I've runtested the main part of the code on FRV and i386, though I can't test most of the drivers. I've also done partial conversion for powerpc and MIPS - these at least compile with minimal configurations. This will affect all archs. Mostly the changes should be relatively easy. Take do_IRQ(), store the regs pointer at the beginning, saving the old one: struct pt_regs *old_regs = set_irq_regs(regs); And put the old one back at the end: set_irq_regs(old_regs); Don't pass regs through to generic_handle_irq() or __do_IRQ(). In timer_interrupt(), this sort of change will be necessary: - update_process_times(user_mode(regs)); - profile_tick(CPU_PROFILING, regs); + update_process_times(user_mode(get_irq_regs())); + profile_tick(CPU_PROFILING); I'd like to move update_process_times()'s use of get_irq_regs() into itself, except that i386, alone of the archs, uses something other than user_mode(). Some notes on the interrupt handling in the drivers: (*) input_dev() is now gone entirely. The regs pointer is no longer stored in the input_dev struct. (*) finish_unlinks() in drivers/usb/host/ohci-q.c needs checking. It does something different depending on whether it's been supplied with a regs pointer or not. (*) Various IRQ handler function pointers have been moved to type irq_handler_t. Signed-Off-By: David Howells <dhowells@redhat.com> (cherry picked from 1b16e7ac850969f38b375e511e3fa2f474a33867 commit)
2006-10-05 13:55:46 +00:00
static irqreturn_t mpcore_wdt_fire(int irq, void *arg)
{
struct mpcore_wdt *wdt = arg;
/* Check it really was our interrupt */
if (readl(wdt->base + TWD_WDOG_INTSTAT)) {
dev_printk(KERN_CRIT, wdt->dev, "Triggered - Reboot ignored.\n");
/* Clear the interrupt on the watchdog */
writel(1, wdt->base + TWD_WDOG_INTSTAT);
return IRQ_HANDLED;
}
return IRQ_NONE;
}
/*
* mpcore_wdt_keepalive - reload the timer
*
* Note that the spec says a DIFFERENT value must be written to the reload
* register each time. The "perturb" variable deals with this by adding 1
* to the count every other time the function is called.
*/
static void mpcore_wdt_keepalive(struct mpcore_wdt *wdt)
{
unsigned int count;
/* Assume prescale is set to 256 */
count = (mpcore_timer_rate / 256) * mpcore_margin;
/* Reload the counter */
writel(count + wdt->perturb, wdt->base + TWD_WDOG_LOAD);
wdt->perturb = wdt->perturb ? 0 : 1;
}
static void mpcore_wdt_stop(struct mpcore_wdt *wdt)
{
writel(0x12345678, wdt->base + TWD_WDOG_DISABLE);
writel(0x87654321, wdt->base + TWD_WDOG_DISABLE);
writel(0x0, wdt->base + TWD_WDOG_CONTROL);
}
static void mpcore_wdt_start(struct mpcore_wdt *wdt)
{
dev_printk(KERN_INFO, wdt->dev, "enabling watchdog.\n");
/* This loads the count register but does NOT start the count yet */
mpcore_wdt_keepalive(wdt);
if (mpcore_noboot) {
/* Enable watchdog - prescale=256, watchdog mode=0, enable=1 */
writel(0x0000FF01, wdt->base + TWD_WDOG_CONTROL);
} else {
/* Enable watchdog - prescale=256, watchdog mode=1, enable=1 */
writel(0x0000FF09, wdt->base + TWD_WDOG_CONTROL);
}
}
static int mpcore_wdt_set_heartbeat(int t)
{
if (t < 0x0001 || t > 0xFFFF)
return -EINVAL;
mpcore_margin = t;
return 0;
}
/*
* /dev/watchdog handling
*/
static int mpcore_wdt_open(struct inode *inode, struct file *file)
{
struct mpcore_wdt *wdt = platform_get_drvdata(mpcore_wdt_dev);
if (test_and_set_bit(0, &wdt->timer_alive))
return -EBUSY;
if (nowayout)
__module_get(THIS_MODULE);
file->private_data = wdt;
/*
* Activate timer
*/
mpcore_wdt_start(wdt);
return nonseekable_open(inode, file);
}
static int mpcore_wdt_release(struct inode *inode, struct file *file)
{
struct mpcore_wdt *wdt = file->private_data;
/*
* Shut off the timer.
* Lock it in if it's a module and we set nowayout
*/
if (wdt->expect_close == 42) {
mpcore_wdt_stop(wdt);
} else {
dev_printk(KERN_CRIT, wdt->dev, "unexpected close, not stopping watchdog!\n");
mpcore_wdt_keepalive(wdt);
}
clear_bit(0, &wdt->timer_alive);
wdt->expect_close = 0;
return 0;
}
static ssize_t mpcore_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos)
{
struct mpcore_wdt *wdt = file->private_data;
/*
* Refresh the timer.
*/
if (len) {
if (!nowayout) {
size_t i;
/* In case it was set long ago */
wdt->expect_close = 0;
for (i = 0; i != len; i++) {
char c;
if (get_user(c, data + i))
return -EFAULT;
if (c == 'V')
wdt->expect_close = 42;
}
}
mpcore_wdt_keepalive(wdt);
}
return len;
}
static struct watchdog_info ident = {
.options = WDIOF_SETTIMEOUT |
WDIOF_KEEPALIVEPING |
WDIOF_MAGICCLOSE,
.identity = "MPcore Watchdog",
};
static int mpcore_wdt_ioctl(struct inode *inode, struct file *file,
unsigned int cmd, unsigned long arg)
{
struct mpcore_wdt *wdt = file->private_data;
int ret;
union {
struct watchdog_info ident;
int i;
} uarg;
if (_IOC_DIR(cmd) && _IOC_SIZE(cmd) > sizeof(uarg))
return -ENOTTY;
if (_IOC_DIR(cmd) & _IOC_WRITE) {
ret = copy_from_user(&uarg, (void __user *)arg, _IOC_SIZE(cmd));
if (ret)
return -EFAULT;
}
switch (cmd) {
case WDIOC_GETSUPPORT:
uarg.ident = ident;
ret = 0;
break;
case WDIOC_SETOPTIONS:
ret = -EINVAL;
if (uarg.i & WDIOS_DISABLECARD) {
mpcore_wdt_stop(wdt);
ret = 0;
}
if (uarg.i & WDIOS_ENABLECARD) {
mpcore_wdt_start(wdt);
ret = 0;
}
break;
case WDIOC_GETSTATUS:
case WDIOC_GETBOOTSTATUS:
uarg.i = 0;
ret = 0;
break;
case WDIOC_KEEPALIVE:
mpcore_wdt_keepalive(wdt);
ret = 0;
break;
case WDIOC_SETTIMEOUT:
ret = mpcore_wdt_set_heartbeat(uarg.i);
if (ret)
break;
mpcore_wdt_keepalive(wdt);
/* Fall */
case WDIOC_GETTIMEOUT:
uarg.i = mpcore_margin;
ret = 0;
break;
default:
return -ENOTTY;
}
if (ret == 0 && _IOC_DIR(cmd) & _IOC_READ) {
ret = copy_to_user((void __user *)arg, &uarg, _IOC_SIZE(cmd));
if (ret)
ret = -EFAULT;
}
return ret;
}
/*
* System shutdown handler. Turn off the watchdog if we're
* restarting or halting the system.
*/
static void mpcore_wdt_shutdown(struct platform_device *dev)
{
struct mpcore_wdt *wdt = platform_get_drvdata(dev);
if (system_state == SYSTEM_RESTART || system_state == SYSTEM_HALT)
mpcore_wdt_stop(wdt);
}
/*
* Kernel Interfaces
*/
static const struct file_operations mpcore_wdt_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
.write = mpcore_wdt_write,
.ioctl = mpcore_wdt_ioctl,
.open = mpcore_wdt_open,
.release = mpcore_wdt_release,
};
static struct miscdevice mpcore_wdt_miscdev = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &mpcore_wdt_fops,
};
static int __devinit mpcore_wdt_probe(struct platform_device *dev)
{
struct mpcore_wdt *wdt;
struct resource *res;
int ret;
/* We only accept one device, and it must have an id of -1 */
if (dev->id != -1)
return -ENODEV;
res = platform_get_resource(dev, IORESOURCE_MEM, 0);
if (!res) {
ret = -ENODEV;
goto err_out;
}
2007-07-19 08:49:03 +00:00
wdt = kzalloc(sizeof(struct mpcore_wdt), GFP_KERNEL);
if (!wdt) {
ret = -ENOMEM;
goto err_out;
}
wdt->dev = &dev->dev;
wdt->irq = platform_get_irq(dev, 0);
if (wdt->irq < 0) {
ret = -ENXIO;
goto err_free;
}
wdt->base = ioremap(res->start, res->end - res->start + 1);
if (!wdt->base) {
ret = -ENOMEM;
goto err_free;
}
mpcore_wdt_miscdev.parent = &dev->dev;
ret = misc_register(&mpcore_wdt_miscdev);
if (ret) {
dev_printk(KERN_ERR, _dev, "cannot register miscdev on minor=%d (err=%d)\n",
WATCHDOG_MINOR, ret);
goto err_misc;
}
ret = request_irq(wdt->irq, mpcore_wdt_fire, IRQF_DISABLED, "mpcore_wdt", wdt);
if (ret) {
dev_printk(KERN_ERR, _dev, "cannot register IRQ%d for watchdog\n", wdt->irq);
goto err_irq;
}
mpcore_wdt_stop(wdt);
platform_set_drvdata(&dev->dev, wdt);
mpcore_wdt_dev = dev;
return 0;
err_irq:
misc_deregister(&mpcore_wdt_miscdev);
err_misc:
iounmap(wdt->base);
err_free:
kfree(wdt);
err_out:
return ret;
}
static int __devexit mpcore_wdt_remove(struct platform_device *dev)
{
struct mpcore_wdt *wdt = platform_get_drvdata(dev);
platform_set_drvdata(dev, NULL);
misc_deregister(&mpcore_wdt_miscdev);
mpcore_wdt_dev = NULL;
free_irq(wdt->irq, wdt);
iounmap(wdt->base);
kfree(wdt);
return 0;
}
/* work with hotplug and coldplug */
MODULE_ALIAS("platform:mpcore_wdt");
static struct platform_driver mpcore_wdt_driver = {
.probe = mpcore_wdt_probe,
.remove = __devexit_p(mpcore_wdt_remove),
.shutdown = mpcore_wdt_shutdown,
.driver = {
.owner = THIS_MODULE,
.name = "mpcore_wdt",
},
};
static char banner[] __initdata = KERN_INFO "MPcore Watchdog Timer: 0.1. mpcore_noboot=%d mpcore_margin=%d sec (nowayout= %d)\n";
static int __init mpcore_wdt_init(void)
{
/*
* Check that the margin value is within it's range;
* if not reset to the default
*/
if (mpcore_wdt_set_heartbeat(mpcore_margin)) {
mpcore_wdt_set_heartbeat(TIMER_MARGIN);
printk(KERN_INFO "mpcore_margin value must be 0<mpcore_margin<65536, using %d\n",
TIMER_MARGIN);
}
printk(banner, mpcore_noboot, mpcore_margin, nowayout);
return platform_driver_register(&mpcore_wdt_driver);
}
static void __exit mpcore_wdt_exit(void)
{
platform_driver_unregister(&mpcore_wdt_driver);
}
module_init(mpcore_wdt_init);
module_exit(mpcore_wdt_exit);
MODULE_AUTHOR("ARM Limited");
MODULE_DESCRIPTION("MPcore Watchdog Device Driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);