arch/mn10300/kernel/mn10300-watchdog.c

   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
  29 static DEFINE_SPINLOCK(watchdog_print_lock);
  30 static unsigned int watchdog;
  31 static unsigned int watchdog_hz = 1;
  32 unsigned int watchdog_alert_counter[NR_CPUS];
  33
  34 EXPORT_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  */
  47 static unsigned int last_irq_sums[NR_CPUS];
  48
  49 int __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
  76 static 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
 104 void __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
 121 static 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
 128 asmlinkage
 129 void 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 }