diff options
Diffstat (limited to 'arch/mn10300/kernel/mn10300-watchdog.c')
| -rw-r--r-- | arch/mn10300/kernel/mn10300-watchdog.c | 183 |
1 files changed, 183 insertions, 0 deletions
diff --git a/arch/mn10300/kernel/mn10300-watchdog.c b/arch/mn10300/kernel/mn10300-watchdog.c new file mode 100644 index 00000000000..10811e981d2 --- /dev/null +++ b/arch/mn10300/kernel/mn10300-watchdog.c @@ -0,0 +1,183 @@ +/* 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(); + u8 wdt, tmp; + + wdt = WDCTR & ~WDCTR_WDCNE; + WDCTR = wdt; + tmp = WDCTR; + NMICR = NMICR_WDIF; + + nmi_count(cpu)++; + kstat_this_cpu.irqs[NMIIRQ]++; + 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; +} |