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/arch/mn10300/kernel/mn10300-watchdog.c

http://github.com/mirrors/linux
C | 205 lines | 141 code | 27 blank | 37 comment | 14 complexity | 78c20e00149bd2e41f4cb5b09e9c1936 MD5 | raw file
  1/* MN10300 Watchdog timer
  2 *
  3 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
  4 * Written by David Howells (dhowells@redhat.com)
  5 * - Derived from arch/i386/kernel/nmi.c
  6 *
  7 * This program is free software; you can redistribute it and/or
  8 * modify it under the terms of the GNU General Public Licence
  9 * as published by the Free Software Foundation; either version
 10 * 2 of the Licence, or (at your option) any later version.
 11 */
 12#include <linux/module.h>
 13#include <linux/sched.h>
 14#include <linux/kernel.h>
 15#include <linux/init.h>
 16#include <linux/delay.h>
 17#include <linux/interrupt.h>
 18#include <linux/kernel_stat.h>
 19#include <linux/nmi.h>
 20#include <asm/processor.h>
 21#include <linux/atomic.h>
 22#include <asm/intctl-regs.h>
 23#include <asm/rtc-regs.h>
 24#include <asm/div64.h>
 25#include <asm/smp.h>
 26#include <asm/gdb-stub.h>
 27#include <proc/clock.h>
 28
 29static DEFINE_SPINLOCK(watchdog_print_lock);
 30static unsigned int watchdog;
 31static unsigned int watchdog_hz = 1;
 32unsigned int watchdog_alert_counter[NR_CPUS];
 33
 34EXPORT_SYMBOL(touch_nmi_watchdog);
 35
 36/*
 37 * the best way to detect whether a CPU has a 'hard lockup' problem
 38 * is to check its timer makes IRQ counts. If they are not
 39 * changing then that CPU has some problem.
 40 *
 41 * since NMIs dont listen to _any_ locks, we have to be extremely
 42 * careful not to rely on unsafe variables. The printk might lock
 43 * up though, so we have to break up any console locks first ...
 44 * [when there will be more tty-related locks, break them up
 45 *  here too!]
 46 */
 47static unsigned int last_irq_sums[NR_CPUS];
 48
 49int __init check_watchdog(void)
 50{
 51	irq_cpustat_t tmp[1];
 52
 53	printk(KERN_INFO "Testing Watchdog... ");
 54
 55	memcpy(tmp, irq_stat, sizeof(tmp));
 56	local_irq_enable();
 57	mdelay((10 * 1000) / watchdog_hz); /* wait 10 ticks */
 58	local_irq_disable();
 59
 60	if (nmi_count(0) - tmp[0].__nmi_count <= 5) {
 61		printk(KERN_WARNING "CPU#%d: Watchdog appears to be stuck!\n",
 62		       0);
 63		return -1;
 64	}
 65
 66	printk(KERN_INFO "OK.\n");
 67
 68	/* now that we know it works we can reduce NMI frequency to something
 69	 * more reasonable; makes a difference in some configs
 70	 */
 71	watchdog_hz = 1;
 72
 73	return 0;
 74}
 75
 76static int __init setup_watchdog(char *str)
 77{
 78	unsigned tmp;
 79	int opt;
 80	u8 ctr;
 81
 82	get_option(&str, &opt);
 83	if (opt != 1)
 84		return 0;
 85
 86	watchdog = opt;
 87	if (watchdog) {
 88		set_intr_stub(EXCEP_WDT, watchdog_handler);
 89		ctr = WDCTR_WDCK_65536th;
 90		WDCTR = WDCTR_WDRST | ctr;
 91		WDCTR = ctr;
 92		tmp = WDCTR;
 93
 94		tmp = __muldiv64u(1 << (16 + ctr * 2), 1000000, MN10300_WDCLK);
 95		tmp = 1000000000 / tmp;
 96		watchdog_hz = (tmp + 500) / 1000;
 97	}
 98
 99	return 1;
100}
101
102__setup("watchdog=", setup_watchdog);
103
104void __init watchdog_go(void)
105{
106	u8 wdt;
107
108	if (watchdog) {
109		printk(KERN_INFO "Watchdog: running at %uHz\n", watchdog_hz);
110		wdt = WDCTR & ~WDCTR_WDCNE;
111		WDCTR = wdt | WDCTR_WDRST;
112		wdt = WDCTR;
113		WDCTR = wdt | WDCTR_WDCNE;
114		wdt = WDCTR;
115
116		check_watchdog();
117	}
118}
119
120#ifdef CONFIG_SMP
121static void watchdog_dump_register(void *dummy)
122{
123	printk(KERN_ERR "--- Register Dump (CPU%d) ---\n", CPUID);
124	show_registers(current_frame());
125}
126#endif
127
128asmlinkage
129void watchdog_interrupt(struct pt_regs *regs, enum exception_code excep)
130{
131	/*
132	 * Since current-> is always on the stack, and we always switch
133	 * the stack NMI-atomically, it's safe to use smp_processor_id().
134	 */
135	int sum, cpu;
136	int irq = NMIIRQ;
137	u8 wdt, tmp;
138
139	wdt = WDCTR & ~WDCTR_WDCNE;
140	WDCTR = wdt;
141	tmp = WDCTR;
142	NMICR = NMICR_WDIF;
143
144	nmi_count(smp_processor_id())++;
145	kstat_incr_irq_this_cpu(irq);
146
147	for_each_online_cpu(cpu) {
148
149		sum = irq_stat[cpu].__irq_count;
150
151		if ((last_irq_sums[cpu] == sum)
152#if defined(CONFIG_GDBSTUB) && defined(CONFIG_SMP)
153			&& !(CHK_GDBSTUB_BUSY()
154			     || atomic_read(&cpu_doing_single_step))
155#endif
156			) {
157			/*
158			 * Ayiee, looks like this CPU is stuck ...
159			 * wait a few IRQs (5 seconds) before doing the oops ...
160			 */
161			watchdog_alert_counter[cpu]++;
162			if (watchdog_alert_counter[cpu] == 5 * watchdog_hz) {
163				spin_lock(&watchdog_print_lock);
164				/*
165				 * We are in trouble anyway, lets at least try
166				 * to get a message out.
167				 */
168				bust_spinlocks(1);
169				printk(KERN_ERR
170				       "NMI Watchdog detected LOCKUP on CPU%d,"
171				       " pc %08lx, registers:\n",
172				       cpu, regs->pc);
173#ifdef CONFIG_SMP
174				printk(KERN_ERR
175				       "--- Register Dump (CPU%d) ---\n",
176				       CPUID);
177#endif
178				show_registers(regs);
179#ifdef CONFIG_SMP
180				smp_nmi_call_function(watchdog_dump_register,
181					NULL, 1);
182#endif
183				printk(KERN_NOTICE "console shuts up ...\n");
184				console_silent();
185				spin_unlock(&watchdog_print_lock);
186				bust_spinlocks(0);
187#ifdef CONFIG_GDBSTUB
188				if (CHK_GDBSTUB_BUSY_AND_ACTIVE())
189					gdbstub_exception(regs, excep);
190				else
191					gdbstub_intercept(regs, excep);
192#endif
193				do_exit(SIGSEGV);
194			}
195		} else {
196			last_irq_sums[cpu] = sum;
197			watchdog_alert_counter[cpu] = 0;
198		}
199	}
200
201	WDCTR = wdt | WDCTR_WDRST;
202	tmp = WDCTR;
203	WDCTR = wdt | WDCTR_WDCNE;
204	tmp = WDCTR;
205}