[PATCH v10 3/8] RISC-V: ACPI: Add acpi_get_cpu_uid() for unified ACPI CPU UID retrieval

[Chengwen Feng <fengchengwen@xxxxxxxxxx>]

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().

Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Chengwen Feng <fengchengwen@xxxxxxxxxx>
Reviewed-by: Jonathan Cameron <jonathan.cameron@xxxxxxxxxx>
---
 arch/riscv/include/asm/acpi.h |  1 +
 arch/riscv/kernel/acpi.c      | 16 ++++++++++++++++
 arch/riscv/kernel/acpi_numa.c |  9 ++++++---
 drivers/acpi/riscv/rhct.c     |  7 ++++++-
 4 files changed, 29 insertions(+), 4 deletions(-)

diff --git a/arch/riscv/include/asm/acpi.h b/arch/riscv/include/asm/acpi.h
index 6e13695120bc..f3520cc85af3 100644
--- a/arch/riscv/include/asm/acpi.h
+++ b/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);
diff --git a/arch/riscv/kernel/acpi.c b/arch/riscv/kernel/acpi.c
index 71698ee11621..322ea92aa39f 100644
--- a/arch/riscv/kernel/acpi.c
+++ b/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);
diff --git a/arch/riscv/kernel/acpi_numa.c b/arch/riscv/kernel/acpi_numa.c
index 130769e3a99c..6a2d4289f806 100644
--- a/arch/riscv/kernel/acpi_numa.c
+++ b/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;
 }
diff --git a/drivers/acpi/riscv/rhct.c b/drivers/acpi/riscv/rhct.c
index caa2c16e1697..8f3f38c64a88 100644
--- a/drivers/acpi/riscv/rhct.c
+++ b/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)
-- 
2.17.1