Blackfin: implement nmi_watchdog for SMP on BF561

Signed-off-by: Graf Yang <graf.yang@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>

1 files changed, 313 insertions, 0 deletions

diff --git a/arch/blackfin/kernel/nmi.c b/arch/blackfin/kernel/nmi.c
new file mode 100644
index 000000000000..19093c17632b
--- /dev/null
+++ b/arch/blackfin/kernel/nmi.c
@@ -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();
+}