Blackfin: implement nmi_watchdog for SMP on BF561
authorGraf Yang <graf.yang@analog.com>
Wed, 20 Jan 2010 10:56:24 +0000 (10:56 +0000)
committerMike Frysinger <vapier@gentoo.org>
Tue, 9 Mar 2010 05:30:49 +0000 (00:30 -0500)
Signed-off-by: Graf Yang <graf.yang@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
arch/blackfin/Kconfig.debug
arch/blackfin/include/asm/irq.h
arch/blackfin/include/asm/nmi.h [new file with mode: 0644]
arch/blackfin/include/asm/smp.h
arch/blackfin/kernel/Makefile
arch/blackfin/kernel/nmi.c [new file with mode: 0644]
arch/blackfin/kernel/time-ts.c
arch/blackfin/mach-common/interrupt.S

index 87f195ee2e06234e50399566b25243e8ca821bda..1460d7b5edc15d2dfffd61c5ab4c07abcf3ce2c2 100644 (file)
@@ -238,6 +238,15 @@ config EARLY_PRINTK
          all of this lives in the init section and is thrown away after the
          kernel boots completely.
 
+config NMI_WATCHDOG
+       bool "Enable NMI watchdog to help debugging lockup on SMP"
+       default n
+       depends on (SMP && !BFIN_SCRATCH_REG_RETN)
+       help
+         If any CPU in the system does not execute the period local timer
+         interrupt for more than 5 seconds, then the NMI handler dumps debug
+         information. This information can be used to debug the lockup.
+
 config CPLB_INFO
        bool "Display the CPLB information"
        help
index 89de539ed0100624ead2e5ea6d7f9790eed11cf2..12f4060a31b034e9cd7190b075da6f58d6d4abaa 100644 (file)
@@ -38,4 +38,8 @@
 
 #include <asm-generic/irq.h>
 
+#ifdef CONFIG_NMI_WATCHDOG
+# define ARCH_HAS_NMI_WATCHDOG
+#endif
+
 #endif                         /* _BFIN_IRQ_H_ */
diff --git a/arch/blackfin/include/asm/nmi.h b/arch/blackfin/include/asm/nmi.h
new file mode 100644 (file)
index 0000000..b9caac4
--- /dev/null
@@ -0,0 +1,12 @@
+/*
+ * Copyright 2010 Analog Devices Inc.
+ *
+ * Licensed under the GPL-2
+ */
+
+#ifndef _BFIN_NMI_H_
+#define _BFIN_NMI_H_
+
+#include <linux/nmi.h>
+
+#endif
index 29fb88219470e3946bf3bd69b6c611457020e216..7f26de09ca9cd53cc7e922bbfaa16022f718a141 100644 (file)
@@ -22,6 +22,7 @@ extern char coreb_trampoline_start, coreb_trampoline_end;
 struct corelock_slot {
        int lock;
 };
+extern struct corelock_slot corelock;
 
 void smp_icache_flush_range_others(unsigned long start,
                                   unsigned long end);
index a8ddbc8ed5af6d430ce5da0bf42ec2cf6ddfb531..346a421f1562fad53d66485d3d8d7ea2b51935ff 100644 (file)
@@ -25,6 +25,7 @@ obj-$(CONFIG_CPLB_INFO)              += cplbinfo.o
 obj-$(CONFIG_MODULES)                += module.o
 obj-$(CONFIG_KGDB)                   += kgdb.o
 obj-$(CONFIG_KGDB_TESTS)             += kgdb_test.o
+obj-$(CONFIG_NMI_WATCHDOG)           += nmi.o
 obj-$(CONFIG_EARLY_PRINTK)           += early_printk.o
 obj-$(CONFIG_EARLY_PRINTK)           += shadow_console.o
 obj-$(CONFIG_STACKTRACE)             += stacktrace.o
diff --git a/arch/blackfin/kernel/nmi.c b/arch/blackfin/kernel/nmi.c
new file mode 100644 (file)
index 0000000..19093c1
--- /dev/null
@@ -0,0 +1,313 @@
+/*
+ * Blackfin nmi_watchdog Driver
+ *
+ * Originally based on bfin_wdt.c
+ * Copyright 2010-2010 Analog Devices Inc.
+ *             Graff Yang <graf.yang@analog.com>
+ *
+ * Enter bugs at http://blackfin.uclinux.org/
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#include <linux/bitops.h>
+#include <linux/hardirq.h>
+#include <linux/sysdev.h>
+#include <linux/pm.h>
+#include <linux/nmi.h>
+#include <linux/smp.h>
+#include <linux/timer.h>
+#include <asm/blackfin.h>
+#include <asm/atomic.h>
+#include <asm/cacheflush.h>
+
+/* Bit in WDOG_CTL that indicates watchdog has expired (WDR0) */
+#define WDOG_EXPIRED 0x8000
+
+/* Masks for WDEV field in WDOG_CTL register */
+#define ICTL_RESET   0x0
+#define ICTL_NMI     0x2
+#define ICTL_GPI     0x4
+#define ICTL_NONE    0x6
+#define ICTL_MASK    0x6
+
+/* Masks for WDEN field in WDOG_CTL register */
+#define WDEN_MASK    0x0FF0
+#define WDEN_ENABLE  0x0000
+#define WDEN_DISABLE 0x0AD0
+
+#define DRV_NAME "nmi-wdt"
+
+#define NMI_WDT_TIMEOUT 5          /* 5 seconds */
+#define NMI_CHECK_TIMEOUT (4 * HZ) /* 4 seconds in jiffies */
+static int nmi_wdt_cpu = 1;
+
+static unsigned int timeout = NMI_WDT_TIMEOUT;
+static int nmi_active;
+
+static unsigned short wdoga_ctl;
+static unsigned int wdoga_cnt;
+static struct corelock_slot saved_corelock;
+static atomic_t nmi_touched[NR_CPUS];
+static struct timer_list ntimer;
+
+enum {
+       COREA_ENTER_NMI = 0,
+       COREA_EXIT_NMI,
+       COREB_EXIT_NMI,
+
+       NMI_EVENT_NR,
+};
+static unsigned long nmi_event __attribute__ ((__section__(".l2.bss")));
+
+/* we are in nmi, non-atomic bit ops is safe */
+static inline void set_nmi_event(int event)
+{
+       __set_bit(event, &nmi_event);
+}
+
+static inline void wait_nmi_event(int event)
+{
+       while (!test_bit(event, &nmi_event))
+               barrier();
+       __clear_bit(event, &nmi_event);
+}
+
+static inline void send_corea_nmi(void)
+{
+       wdoga_ctl = bfin_read_WDOGA_CTL();
+       wdoga_cnt = bfin_read_WDOGA_CNT();
+
+       bfin_write_WDOGA_CTL(WDEN_DISABLE);
+       bfin_write_WDOGA_CNT(0);
+       bfin_write_WDOGA_CTL(WDEN_ENABLE | ICTL_NMI);
+}
+
+static inline void restore_corea_nmi(void)
+{
+       bfin_write_WDOGA_CTL(WDEN_DISABLE);
+       bfin_write_WDOGA_CTL(WDOG_EXPIRED | WDEN_DISABLE | ICTL_NONE);
+
+       bfin_write_WDOGA_CNT(wdoga_cnt);
+       bfin_write_WDOGA_CTL(wdoga_ctl);
+}
+
+static inline void save_corelock(void)
+{
+       saved_corelock = corelock;
+       corelock.lock = 0;
+}
+
+static inline void restore_corelock(void)
+{
+       corelock = saved_corelock;
+}
+
+
+static inline void nmi_wdt_keepalive(void)
+{
+       bfin_write_WDOGB_STAT(0);
+}
+
+static inline void nmi_wdt_stop(void)
+{
+       bfin_write_WDOGB_CTL(WDEN_DISABLE);
+}
+
+/* before calling this function, you must stop the WDT */
+static inline void nmi_wdt_clear(void)
+{
+       /* clear TRO bit, disable event generation */
+       bfin_write_WDOGB_CTL(WDOG_EXPIRED | WDEN_DISABLE | ICTL_NONE);
+}
+
+static inline void nmi_wdt_start(void)
+{
+       bfin_write_WDOGB_CTL(WDEN_ENABLE | ICTL_NMI);
+}
+
+static inline int nmi_wdt_running(void)
+{
+       return ((bfin_read_WDOGB_CTL() & WDEN_MASK) != WDEN_DISABLE);
+}
+
+static inline int nmi_wdt_set_timeout(unsigned long t)
+{
+       u32 cnt, max_t, sclk;
+       int run;
+
+       sclk = get_sclk();
+       max_t = -1 / sclk;
+       cnt = t * sclk;
+       if (t > max_t) {
+               pr_warning("NMI: timeout value is too large\n");
+               return -EINVAL;
+       }
+
+       run = nmi_wdt_running();
+       nmi_wdt_stop();
+       bfin_write_WDOGB_CNT(cnt);
+       if (run)
+               nmi_wdt_start();
+
+       timeout = t;
+
+       return 0;
+}
+
+int check_nmi_wdt_touched(void)
+{
+       unsigned int this_cpu = smp_processor_id();
+       unsigned int cpu;
+
+       cpumask_t mask = cpu_online_map;
+
+       if (!atomic_read(&nmi_touched[this_cpu]))
+               return 0;
+
+       atomic_set(&nmi_touched[this_cpu], 0);
+
+       cpu_clear(this_cpu, mask);
+       for_each_cpu_mask(cpu, mask) {
+               invalidate_dcache_range((unsigned long)(&nmi_touched[cpu]),
+                               (unsigned long)(&nmi_touched[cpu]));
+               if (!atomic_read(&nmi_touched[cpu]))
+                       return 0;
+               atomic_set(&nmi_touched[cpu], 0);
+       }
+
+       return 1;
+}
+
+static void nmi_wdt_timer(unsigned long data)
+{
+       if (check_nmi_wdt_touched())
+               nmi_wdt_keepalive();
+
+       mod_timer(&ntimer, jiffies + NMI_CHECK_TIMEOUT);
+}
+
+static int __init init_nmi_wdt(void)
+{
+       nmi_wdt_set_timeout(timeout);
+       nmi_wdt_start();
+       nmi_active = true;
+
+       init_timer(&ntimer);
+       ntimer.function = nmi_wdt_timer;
+       ntimer.expires = jiffies + NMI_CHECK_TIMEOUT;
+       add_timer(&ntimer);
+
+       pr_info("nmi_wdt: initialized: timeout=%d sec\n", timeout);
+       return 0;
+}
+device_initcall(init_nmi_wdt);
+
+void touch_nmi_watchdog(void)
+{
+       atomic_set(&nmi_touched[smp_processor_id()], 1);
+}
+
+/* Suspend/resume support */
+#ifdef CONFIG_PM
+static int nmi_wdt_suspend(struct sys_device *dev, pm_message_t state)
+{
+       nmi_wdt_stop();
+       return 0;
+}
+
+static int nmi_wdt_resume(struct sys_device *dev)
+{
+       if (nmi_active)
+               nmi_wdt_start();
+       return 0;
+}
+
+static struct sysdev_class nmi_sysclass = {
+       .name           = DRV_NAME,
+       .resume         = nmi_wdt_resume,
+       .suspend        = nmi_wdt_suspend,
+};
+
+static struct sys_device device_nmi_wdt = {
+       .id     = 0,
+       .cls    = &nmi_sysclass,
+};
+
+static int __init init_nmi_wdt_sysfs(void)
+{
+       int error;
+
+       if (!nmi_active)
+               return 0;
+
+       error = sysdev_class_register(&nmi_sysclass);
+       if (!error)
+               error = sysdev_register(&device_nmi_wdt);
+       return error;
+}
+late_initcall(init_nmi_wdt_sysfs);
+
+#endif /* CONFIG_PM */
+
+
+asmlinkage notrace void do_nmi(struct pt_regs *fp)
+{
+       unsigned int cpu = smp_processor_id();
+       nmi_enter();
+
+       cpu_pda[cpu].__nmi_count += 1;
+
+       if (cpu == nmi_wdt_cpu) {
+               /* CoreB goes here first */
+
+               /* reload the WDOG_STAT */
+               nmi_wdt_keepalive();
+
+               /* clear nmi interrupt for CoreB */
+               nmi_wdt_stop();
+               nmi_wdt_clear();
+
+               /* trigger NMI interrupt of CoreA */
+               send_corea_nmi();
+
+               /* waiting CoreB to enter NMI */
+               wait_nmi_event(COREA_ENTER_NMI);
+
+               /* recover WDOGA's settings */
+               restore_corea_nmi();
+
+               save_corelock();
+
+               /* corelock is save/cleared, CoreA is dummping messages */
+
+               wait_nmi_event(COREA_EXIT_NMI);
+       } else {
+               /* OK, CoreA entered NMI */
+               set_nmi_event(COREA_ENTER_NMI);
+       }
+
+       pr_emerg("\nNMI Watchdog detected LOCKUP, dump for CPU %d\n", cpu);
+       dump_bfin_process(fp);
+       dump_bfin_mem(fp);
+       show_regs(fp);
+       dump_bfin_trace_buffer();
+       show_stack(current, (unsigned long *)fp);
+
+       if (cpu == nmi_wdt_cpu) {
+               pr_emerg("This fault is not recoverable, sorry!\n");
+
+               /* CoreA dump finished, restore the corelock */
+               restore_corelock();
+
+               set_nmi_event(COREB_EXIT_NMI);
+       } else {
+               /* CoreB dump finished, notice the CoreA we are done */
+               set_nmi_event(COREA_EXIT_NMI);
+
+               /* synchronize with CoreA */
+               wait_nmi_event(COREB_EXIT_NMI);
+       }
+
+       nmi_exit();
+}
index a351f97c87a3d24ef6553c4dd4af0d6784a60622..41a907596c70dbbd6999d193bd1aaba91ca17996 100644 (file)
@@ -21,6 +21,7 @@
 #include <asm/blackfin.h>
 #include <asm/time.h>
 #include <asm/gptimers.h>
+#include <asm/nmi.h>
 
 /* Accelerators for sched_clock()
  * convert from cycles(64bits) => nanoseconds (64bits)
@@ -309,6 +310,9 @@ irqreturn_t bfin_coretmr_interrupt(int irq, void *dev_id)
 
        smp_mb();
        evt->event_handler(evt);
+
+       touch_nmi_watchdog();
+
        return IRQ_HANDLED;
 }
 
index 0a0c088ead8ce1074c4aa6deeb5c1c78ddc6b552..cee62cf4acd429d07b4d84991c6e088f795a1eb4 100644 (file)
@@ -194,12 +194,28 @@ ENTRY(_evt_ivhw)
 ENDPROC(_evt_ivhw)
 
 /* Interrupt routine for evt2 (NMI).
- * We don't actually use this, so just return.
  * For inner circle type details, please see:
  * http://docs.blackfin.uclinux.org/doku.php?id=linux-kernel:nmi
  */
 ENTRY(_evt_nmi)
+#ifndef CONFIG_NMI_WATCHDOG
 .weak _evt_nmi
+#else
+       /* Not take account of CPLBs, this handler will not return */
+       SAVE_ALL_SYS
+       r0 = sp;
+       r1 = retn;
+       [sp + PT_PC] = r1;
+       trace_buffer_save(p4,r5);
+
+       ANOMALY_283_315_WORKAROUND(p4, r5)
+
+       SP += -12;
+       call _do_nmi;
+       SP += 12;
+1:
+       jump 1b;
+#endif
        rtn;
 ENDPROC(_evt_nmi)