RISC-V: ACPI: Add acpi_get_cpu_uid() for unified ACPI CPU UID retrieval

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

And also update acpi_numa.c and rhct.c to use the new interface instead
of the legacy get_acpi_id_for_cpu().

Signed-off-by: Chengwen Feng <fengchengwen@huawei.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Link: https://patch.msgid.link/20260401081640.26875-4-fengchengwen@huawei.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Author: fengchengwen

arch/riscv/include/asm/acpi.h

@@ -65,6 +65,7 @@ static inline u32 get_acpi_id_for_cpu(int cpu)
 {
 	return acpi_cpu_get_madt_rintc(cpu)->uid;
 }
+int acpi_get_cpu_uid(unsigned int cpu, u32 *uid);
 
 int acpi_get_riscv_isa(struct acpi_table_header *table,
 		       unsigned int cpu, const char **isa);

arch/riscv/kernel/acpi.c

@@ -337,3 +337,19 @@ int raw_pci_write(unsigned int domain, unsigned int bus,
 }
 
 #endif	/* CONFIG_PCI */
+
+int acpi_get_cpu_uid(unsigned int cpu, u32 *uid)
+{
+	struct acpi_madt_rintc *rintc;
+
+	if (cpu >= nr_cpu_ids)
+		return -EINVAL;
+
+	rintc = acpi_cpu_get_madt_rintc(cpu);
+	if (!rintc)
+		return -ENODEV;
+
+	*uid = rintc->uid;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(acpi_get_cpu_uid);

arch/riscv/kernel/acpi_numa.c

@@ -37,11 +37,14 @@ static int __init acpi_numa_get_nid(unsigned int cpu)
 
 static inline int get_cpu_for_acpi_id(u32 uid)
 {
-	int cpu;
+	u32 cpu_uid;
+	int ret;
 
-	for (cpu = 0; cpu < nr_cpu_ids; cpu++)
-		if (uid == get_acpi_id_for_cpu(cpu))
+	for (int cpu = 0; cpu < nr_cpu_ids; cpu++) {
+		ret = acpi_get_cpu_uid(cpu, &cpu_uid);
+		if (ret == 0 && uid == cpu_uid)
 			return cpu;
+	}
 
 	return -EINVAL;
 }

drivers/acpi/riscv/rhct.c

@@ -44,10 +44,15 @@ int acpi_get_riscv_isa(struct acpi_table_header *table, unsigned int cpu, const
 	struct acpi_rhct_isa_string *isa_node;
 	struct acpi_table_rhct *rhct;
 	u32 *hart_info_node_offset;
-	u32 acpi_cpu_id = get_acpi_id_for_cpu(cpu);
+	u32 acpi_cpu_id;
+	int ret;
 
 	BUG_ON(acpi_disabled);
 
+	ret = acpi_get_cpu_uid(cpu, &acpi_cpu_id);
+	if (ret != 0)
+		return ret;
+
 	if (!table) {
 		rhct = acpi_get_rhct();
 		if (!rhct)