MIPS: support for generic clockevents broadcast

This patch adds support for generic clockevents broadcast using the a
dummy clockevent device and the tick_broadcast function introduced by
commit 12ad1000 "clockevents: Add generic timer broadcast function".
Signed-off-by: Paul Burton <paul.burton@imgtec.com>

arch/mips/Kconfig

@@ -51,6 +51,7 @@ config MIPS
 	select HAVE_DEBUG_STACKOVERFLOW
 	select HAVE_CC_STACKPROTECTOR
 	select CPU_PM if CPU_IDLE
+	select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
 
 menu "Machine selection"
 

arch/mips/kernel/smp.c

@@ -404,3 +404,46 @@ void dump_send_ipi(void (*dump_ipi_callback)(void *))
 }
 EXPORT_SYMBOL(dump_send_ipi);
 #endif
+
+#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
+
+static DEFINE_PER_CPU(atomic_t, tick_broadcast_count);
+static DEFINE_PER_CPU(struct call_single_data, tick_broadcast_csd);
+
+void tick_broadcast(const struct cpumask *mask)
+{
+	atomic_t *count;
+	struct call_single_data *csd;
+	int cpu;
+
+	for_each_cpu(cpu, mask) {
+		count = &per_cpu(tick_broadcast_count, cpu);
+		csd = &per_cpu(tick_broadcast_csd, cpu);
+
+		if (atomic_inc_return(count) == 1)
+			smp_call_function_single_async(cpu, csd);
+	}
+}
+
+static void tick_broadcast_callee(void *info)
+{
+	int cpu = smp_processor_id();
+	tick_receive_broadcast();
+	atomic_set(&per_cpu(tick_broadcast_count, cpu), 0);
+}
+
+static int __init tick_broadcast_init(void)
+{
+	struct call_single_data *csd;
+	int cpu;
+
+	for (cpu = 0; cpu < NR_CPUS; cpu++) {
+		csd = &per_cpu(tick_broadcast_csd, cpu);
+		csd->func = tick_broadcast_callee;
+	}
+
+	return 0;
+}
+early_initcall(tick_broadcast_init);
+
+#endif /* CONFIG_GENERIC_CLOCKEVENTS_BROADCAST */