+/*
+ * percpu heartbeat timer
+ */
+static void uv_heartbeat(unsigned long ignored)
+{
+ struct timer_list *timer = &uv_hub_info->scir.timer;
+ unsigned char bits = uv_hub_info->scir.state;
+
+ /* flip heartbeat bit */
+ bits ^= SCIR_CPU_HEARTBEAT;
+
+ /* is this cpu idle? */
+ if (idle_cpu(raw_smp_processor_id()))
+ bits &= ~SCIR_CPU_ACTIVITY;
+ else
+ bits |= SCIR_CPU_ACTIVITY;
+
+ /* update system controller interface reg */
+ uv_set_scir_bits(bits);
+
+ /* enable next timer period */
+ mod_timer(timer, jiffies + SCIR_CPU_HB_INTERVAL);
+}
+
+static void __cpuinit uv_heartbeat_enable(int cpu)
+{
+ if (!uv_cpu_hub_info(cpu)->scir.enabled) {
+ struct timer_list *timer = &uv_cpu_hub_info(cpu)->scir.timer;
+
+ uv_set_cpu_scir_bits(cpu, SCIR_CPU_HEARTBEAT|SCIR_CPU_ACTIVITY);
+ setup_timer(timer, uv_heartbeat, cpu);
+ timer->expires = jiffies + SCIR_CPU_HB_INTERVAL;
+ add_timer_on(timer, cpu);
+ uv_cpu_hub_info(cpu)->scir.enabled = 1;
+ }
+
+ /* check boot cpu */
+ if (!uv_cpu_hub_info(0)->scir.enabled)
+ uv_heartbeat_enable(0);
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+static void __cpuinit uv_heartbeat_disable(int cpu)
+{
+ if (uv_cpu_hub_info(cpu)->scir.enabled) {
+ uv_cpu_hub_info(cpu)->scir.enabled = 0;
+ del_timer(&uv_cpu_hub_info(cpu)->scir.timer);
+ }
+ uv_set_cpu_scir_bits(cpu, 0xff);
+}
+
+/*
+ * cpu hotplug notifier
+ */
+static __cpuinit int uv_scir_cpu_notify(struct notifier_block *self,
+ unsigned long action, void *hcpu)
+{
+ long cpu = (long)hcpu;
+
+ switch (action) {
+ case CPU_ONLINE:
+ uv_heartbeat_enable(cpu);
+ break;
+ case CPU_DOWN_PREPARE:
+ uv_heartbeat_disable(cpu);
+ break;
+ default:
+ break;
+ }
+ return NOTIFY_OK;
+}
+
+static __init void uv_scir_register_cpu_notifier(void)
+{
+ hotcpu_notifier(uv_scir_cpu_notify, 0);
+}
+
+#else /* !CONFIG_HOTPLUG_CPU */
+
+static __init void uv_scir_register_cpu_notifier(void)
+{
+}
+
+static __init int uv_init_heartbeat(void)
+{
+ int cpu;
+
+ if (is_uv_system())
+ for_each_online_cpu(cpu)
+ uv_heartbeat_enable(cpu);
+ return 0;
+}
+
+late_initcall(uv_init_heartbeat);
+
+#endif /* !CONFIG_HOTPLUG_CPU */
+