csky: SMP support

This patch adds boot, ipi, hotplug codes for SMP.

Signed-off-by: Guo Ren <ren_guo@c-sky.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>

arch/csky/include/asm/smp.h

@@ -0,0 +1,26 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __ASM_CSKY_SMP_H
+#define __ASM_CSKY_SMP_H
+
+#include <linux/cpumask.h>
+#include <linux/irqreturn.h>
+#include <linux/threads.h>
+
+#ifdef CONFIG_SMP
+
+void __init setup_smp(void);
+
+void __init setup_smp_ipi(void);
+
+void arch_send_call_function_ipi_mask(struct cpumask *mask);
+
+void arch_send_call_function_single_ipi(int cpu);
+
+void __init set_send_ipi(void (*func)(const struct cpumask *mask), int irq);
+
+#define raw_smp_processor_id()	(current_thread_info()->cpu)
+
+#endif /* CONFIG_SMP */
+
+#endif /* __ASM_CSKY_SMP_H */