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David Howellsb920de12008-02-08 04:19:31 -08001/* 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 <asm/system.h>
22#include <asm/atomic.h>
23#include <asm/intctl-regs.h>
24#include <asm/rtc-regs.h>
25#include <asm/div64.h>
26#include <asm/smp.h>
27#include <asm/gdb-stub.h>
David Howells2f2a2132009-04-10 14:33:48 +010028#include <proc/clock.h>
David Howellsb920de12008-02-08 04:19:31 -080029
30static DEFINE_SPINLOCK(watchdog_print_lock);
31static unsigned int watchdog;
32static unsigned int watchdog_hz = 1;
33unsigned int watchdog_alert_counter;
34
35EXPORT_SYMBOL(touch_nmi_watchdog);
36
37/*
38 * the best way to detect whether a CPU has a 'hard lockup' problem
39 * is to check its timer makes IRQ counts. If they are not
40 * changing then that CPU has some problem.
41 *
42 * as these watchdog NMI IRQs are generated on every CPU, we only
43 * have to check the current processor.
44 *
45 * since NMIs dont listen to _any_ locks, we have to be extremely
46 * careful not to rely on unsafe variables. The printk might lock
47 * up though, so we have to break up any console locks first ...
48 * [when there will be more tty-related locks, break them up
49 * here too!]
50 */
51static unsigned int last_irq_sums[NR_CPUS];
52
53int __init check_watchdog(void)
54{
55 irq_cpustat_t tmp[1];
56
57 printk(KERN_INFO "Testing Watchdog... ");
58
59 memcpy(tmp, irq_stat, sizeof(tmp));
60 local_irq_enable();
61 mdelay((10 * 1000) / watchdog_hz); /* wait 10 ticks */
62 local_irq_disable();
63
64 if (nmi_count(0) - tmp[0].__nmi_count <= 5) {
65 printk(KERN_WARNING "CPU#%d: Watchdog appears to be stuck!\n",
66 0);
67 return -1;
68 }
69
70 printk(KERN_INFO "OK.\n");
71
72 /* now that we know it works we can reduce NMI frequency to
73 * something more reasonable; makes a difference in some configs
74 */
75 watchdog_hz = 1;
76
77 return 0;
78}
79
80static int __init setup_watchdog(char *str)
81{
82 unsigned tmp;
83 int opt;
84 u8 ctr;
85
86 get_option(&str, &opt);
87 if (opt != 1)
88 return 0;
89
90 watchdog = opt;
91 if (watchdog) {
92 set_intr_stub(EXCEP_WDT, watchdog_handler);
93 ctr = WDCTR_WDCK_65536th;
94 WDCTR = WDCTR_WDRST | ctr;
95 WDCTR = ctr;
96 tmp = WDCTR;
97
98 tmp = __muldiv64u(1 << (16 + ctr * 2), 1000000, MN10300_WDCLK);
99 tmp = 1000000000 / tmp;
100 watchdog_hz = (tmp + 500) / 1000;
101 }
102
103 return 1;
104}
105
106__setup("watchdog=", setup_watchdog);
107
108void __init watchdog_go(void)
109{
110 u8 wdt;
111
112 if (watchdog) {
113 printk(KERN_INFO "Watchdog: running at %uHz\n", watchdog_hz);
114 wdt = WDCTR & ~WDCTR_WDCNE;
115 WDCTR = wdt | WDCTR_WDRST;
116 wdt = WDCTR;
117 WDCTR = wdt | WDCTR_WDCNE;
118 wdt = WDCTR;
119
120 check_watchdog();
121 }
122}
123
124asmlinkage
125void watchdog_interrupt(struct pt_regs *regs, enum exception_code excep)
126{
127
128 /*
129 * Since current-> is always on the stack, and we always switch
130 * the stack NMI-atomically, it's safe to use smp_processor_id().
131 */
132 int sum, cpu = smp_processor_id();
Mike Travisd2287f52009-01-14 15:43:54 -0800133 int irq = NMIIRQ;
David Howellsb920de12008-02-08 04:19:31 -0800134 u8 wdt, tmp;
135
136 wdt = WDCTR & ~WDCTR_WDCNE;
137 WDCTR = wdt;
138 tmp = WDCTR;
139 NMICR = NMICR_WDIF;
140
141 nmi_count(cpu)++;
Mike Travisd2287f52009-01-14 15:43:54 -0800142 kstat_incr_irqs_this_cpu(irq, irq_to_desc(irq));
David Howellsb920de12008-02-08 04:19:31 -0800143 sum = irq_stat[cpu].__irq_count;
144
145 if (last_irq_sums[cpu] == sum) {
146 /*
147 * Ayiee, looks like this CPU is stuck ...
148 * wait a few IRQs (5 seconds) before doing the oops ...
149 */
150 watchdog_alert_counter++;
151 if (watchdog_alert_counter == 5 * watchdog_hz) {
152 spin_lock(&watchdog_print_lock);
153 /*
154 * We are in trouble anyway, lets at least try
155 * to get a message out.
156 */
157 bust_spinlocks(1);
158 printk(KERN_ERR
159 "NMI Watchdog detected LOCKUP on CPU%d,"
160 " pc %08lx, registers:\n",
161 cpu, regs->pc);
162 show_registers(regs);
163 printk("console shuts up ...\n");
164 console_silent();
165 spin_unlock(&watchdog_print_lock);
166 bust_spinlocks(0);
167#ifdef CONFIG_GDBSTUB
168 if (gdbstub_busy)
169 gdbstub_exception(regs, excep);
170 else
171 gdbstub_intercept(regs, excep);
172#endif
173 do_exit(SIGSEGV);
174 }
175 } else {
176 last_irq_sums[cpu] = sum;
177 watchdog_alert_counter = 0;
178 }
179
180 WDCTR = wdt | WDCTR_WDRST;
181 tmp = WDCTR;
182 WDCTR = wdt | WDCTR_WDCNE;
183 tmp = WDCTR;
184}