As a step towards unifying the interface for retrieving ACPI CPU UID
across architectures, introduce a new function acpi_get_cpu_uid() for
loongarch. While at it, add input validation to make the code more
robust.

Cc: stable@vger.kernel.org
Signed-off-by: Chengwen Feng <fengchengwen@huawei.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
---
 arch/loongarch/include/asm/acpi.h | 1 +
 arch/loongarch/kernel/acpi.c      | 9 +++++++++
 2 files changed, 10 insertions(+)

diff --git a/arch/loongarch/include/asm/acpi.h b/arch/loongarch/include/asm/acpi.h
index 7376840fa9f7..8bb101b4557e 100644
--- a/arch/loongarch/include/asm/acpi.h
+++ b/arch/loongarch/include/asm/acpi.h
@@ -44,6 +44,7 @@ static inline u32 get_acpi_id_for_cpu(unsigned int cpu)
 {
 	return acpi_core_pic[cpu_logical_map(cpu)].processor_id;
 }
+int acpi_get_cpu_uid(unsigned int cpu, u32 *uid);
 
 #endif /* !CONFIG_ACPI */
 
diff --git a/arch/loongarch/kernel/acpi.c b/arch/loongarch/kernel/acpi.c
index 1367ca759468..058f0dbe8e8f 100644
--- a/arch/loongarch/kernel/acpi.c
+++ b/arch/loongarch/kernel/acpi.c
@@ -385,3 +385,12 @@ int acpi_unmap_cpu(int cpu)
 EXPORT_SYMBOL(acpi_unmap_cpu);
 
 #endif /* CONFIG_ACPI_HOTPLUG_CPU */
+
+int acpi_get_cpu_uid(unsigned int cpu, u32 *uid)
+{
+	if (cpu >= nr_cpu_ids)
+		return -EINVAL;
+	*uid = acpi_core_pic[cpu_logical_map(cpu)].processor_id;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(acpi_get_cpu_uid);
-- 
2.17.1