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