[RFC PATCH v2 3/3] arm64: Add CPU hotplug support

[Xiongfeng Wang]

To support CPU hotplug, we need to implement 'acpi_(un)map_cpu()' and
'arch_(un)register_cpu()' for ARM64. These functions are called in
'acpi_processor_hotadd_init()/acpi_processor_remove()' when the CPU is hot
added into or hot removed from the system.

Signed-off-by: Xiongfeng Wang <wangxiongfeng2@xxxxxxxxxx>
---
 arch/arm64/kernel/acpi.c  | 22 ++++++++++++++++++++++
 arch/arm64/kernel/setup.c | 17 +++++++++++++++++
 2 files changed, 39 insertions(+)

diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
index 2804330..57835fa 100644
--- a/arch/arm64/kernel/acpi.c
+++ b/arch/arm64/kernel/acpi.c
@@ -25,6 +25,7 @@
 #include <linux/serial_core.h>
 
 #include <acpi/ghes.h>
+#include <acpi/processor.h>
 #include <asm/cputype.h>
 #include <asm/cpu_ops.h>
 #include <asm/daifflags.h>
@@ -284,3 +285,24 @@ int apei_claim_sea(struct pt_regs *regs)
 
 	return err;
 }
+
+int acpi_map_cpu(acpi_handle handle, phys_cpuid_t physid, u32 acpi_id,
+		 int *pcpu)
+{
+	int cpu;
+
+	cpu = acpi_map_cpuid(physid, acpi_id);
+	*pcpu = cpu;
+	set_cpu_present(cpu, true);
+
+	return 0;
+}
+EXPORT_SYMBOL(acpi_map_cpu);
+
+int acpi_unmap_cpu(int cpu)
+{
+	set_cpu_present(cpu, false);
+
+	return 0;
+}
+EXPORT_SYMBOL(acpi_unmap_cpu);
diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index 7f4d12a..f2a881e 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -398,3 +398,20 @@ static int __init register_kernel_offset_dumper(void)
 	return 0;
 }
 __initcall(register_kernel_offset_dumper);
+
+int arch_register_cpu(int num)
+{
+	struct cpu *cpu = &per_cpu(cpu_data.cpu, num);
+
+	cpu->hotpluggable = 1;
+	return register_cpu(cpu, num);
+}
+EXPORT_SYMBOL(arch_register_cpu);
+
+void arch_unregister_cpu(int num)
+{
+	struct cpu *cpu = &per_cpu(cpu_data.cpu, num);
+
+	unregister_cpu(cpu);
+}
+EXPORT_SYMBOL(arch_unregister_cpu);
-- 
1.7.12.4