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-rw-r--r--arch/mn10300/kernel/mn10300-watchdog.c183
1 files changed, 183 insertions, 0 deletions
diff --git a/arch/mn10300/kernel/mn10300-watchdog.c b/arch/mn10300/kernel/mn10300-watchdog.c
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+/* 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;
+}