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/* MN10300 Watchdog timer
*
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
* - Derived from arch/i386/kernel/nmi.c
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/kernel_stat.h>
#include <linux/nmi.h>
#include <asm/processor.h>
#include <asm/system.h>
#include <asm/atomic.h>
#include <asm/intctl-regs.h>
#include <asm/rtc-regs.h>
#include <asm/div64.h>
#include <asm/smp.h>
#include <asm/gdb-stub.h>
#include <asm/proc/clock.h>
static DEFINE_SPINLOCK(watchdog_print_lock);
static unsigned int watchdog;
static unsigned int watchdog_hz = 1;
unsigned int watchdog_alert_counter;
EXPORT_SYMBOL(touch_nmi_watchdog);
/*
* the best way to detect whether a CPU has a 'hard lockup' problem
* is to check its timer makes IRQ counts. If they are not
* changing then that CPU has some problem.
*
* as these watchdog NMI IRQs are generated on every CPU, we only
* have to check the current processor.
*
* since NMIs dont listen to _any_ locks, we have to be extremely
* careful not to rely on unsafe variables. The printk might lock
* up though, so we have to break up any console locks first ...
* [when there will be more tty-related locks, break them up
* here too!]
*/
static unsigned int last_irq_sums[NR_CPUS];
int __init check_watchdog(void)
{
irq_cpustat_t tmp[1];
printk(KERN_INFO "Testing Watchdog... ");
memcpy(tmp, irq_stat, sizeof(tmp));
local_irq_enable();
mdelay((10 * 1000) / watchdog_hz); /* wait 10 ticks */
local_irq_disable();
if (nmi_count(0) - tmp[0].__nmi_count <= 5) {
printk(KERN_WARNING "CPU#%d: Watchdog appears to be stuck!\n",
0);
return -1;
}
printk(KERN_INFO "OK.\n");
/* now that we know it works we can reduce NMI frequency to
* something more reasonable; makes a difference in some configs
*/
watchdog_hz = 1;
return 0;
}
static int __init setup_watchdog(char *str)
{
unsigned tmp;
int opt;
u8 ctr;
get_option(&str, &opt);
if (opt != 1)
return 0;
watchdog = opt;
if (watchdog) {
set_intr_stub(EXCEP_WDT, watchdog_handler);
ctr = WDCTR_WDCK_65536th;
WDCTR = WDCTR_WDRST | ctr;
WDCTR = ctr;
tmp = WDCTR;
tmp = __muldiv64u(1 << (16 + ctr * 2), 1000000, MN10300_WDCLK);
tmp = 1000000000 / tmp;
watchdog_hz = (tmp + 500) / 1000;
}
return 1;
}
__setup("watchdog=", setup_watchdog);
void __init watchdog_go(void)
{
u8 wdt;
if (watchdog) {
printk(KERN_INFO "Watchdog: running at %uHz\n", watchdog_hz);
wdt = WDCTR & ~WDCTR_WDCNE;
WDCTR = wdt | WDCTR_WDRST;
wdt = WDCTR;
WDCTR = wdt | WDCTR_WDCNE;
wdt = WDCTR;
check_watchdog();
}
}
asmlinkage
void watchdog_interrupt(struct pt_regs *regs, enum exception_code excep)
{
/*
* Since current-> is always on the stack, and we always switch
* the stack NMI-atomically, it's safe to use smp_processor_id().
*/
int sum, cpu = smp_processor_id();
int irq = NMIIRQ;
u8 wdt, tmp;
wdt = WDCTR & ~WDCTR_WDCNE;
WDCTR = wdt;
tmp = WDCTR;
NMICR = NMICR_WDIF;
nmi_count(cpu)++;
kstat_incr_irqs_this_cpu(irq, irq_to_desc(irq));
sum = irq_stat[cpu].__irq_count;
if (last_irq_sums[cpu] == sum) {
/*
* Ayiee, looks like this CPU is stuck ...
* wait a few IRQs (5 seconds) before doing the oops ...
*/
watchdog_alert_counter++;
if (watchdog_alert_counter == 5 * watchdog_hz) {
spin_lock(&watchdog_print_lock);
/*
* We are in trouble anyway, lets at least try
* to get a message out.
*/
bust_spinlocks(1);
printk(KERN_ERR
"NMI Watchdog detected LOCKUP on CPU%d,"
" pc %08lx, registers:\n",
cpu, regs->pc);
show_registers(regs);
printk("console shuts up ...\n");
console_silent();
spin_unlock(&watchdog_print_lock);
bust_spinlocks(0);
#ifdef CONFIG_GDBSTUB
if (gdbstub_busy)
gdbstub_exception(regs, excep);
else
gdbstub_intercept(regs, excep);
#endif
do_exit(SIGSEGV);
}
} else {
last_irq_sums[cpu] = sum;
watchdog_alert_counter = 0;
}
WDCTR = wdt | WDCTR_WDRST;
tmp = WDCTR;
WDCTR = wdt | WDCTR_WDCNE;
tmp = WDCTR;
}
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