arch_topology: move parse_acpi_topology() to common code

Currently, RISC-V lacks arch-specific registers for CPU topology
properties and must get them from ACPI. Thus, parse_acpi_topology()
is moved from arm64/ to drivers/ for RISC-V reuse.

Signed-off-by: Yunhui Cui <[e-mail]>
Reviewed-by: Sudeep Holla <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

arch/arm64/include/asm/topology.h

···
 #define arch_scale_hw_pressure topology_get_hw_pressure
 #define arch_update_hw_pressure	topology_update_hw_pressure
 
+#undef arch_cpu_is_threaded
+#define arch_cpu_is_threaded() (read_cpuid_mpidr() & MPIDR_MT_BITMASK)
+
 #include <asm-generic/topology.h>
 
 #endif /* _ASM_ARM_TOPOLOGY_H */

arch/arm64/kernel/topology.c

···
 #include <asm/cputype.h>
 #include <asm/topology.h>
 
-#ifdef CONFIG_ACPI
-static bool __init acpi_cpu_is_threaded(int cpu)
-{
-	int is_threaded = acpi_pptt_cpu_is_thread(cpu);
-
-	/*
-	 * if the PPTT doesn't have thread information, assume a homogeneous
-	 * machine and return the current CPU's thread state.
-	 */
-	if (is_threaded < 0)
-		is_threaded = read_cpuid_mpidr() & MPIDR_MT_BITMASK;
-
-	return !!is_threaded;
-}
-
-struct cpu_smt_info {
-	unsigned int thread_num;
-	int core_id;
-};
-
-/*
- * Propagate the topology information of the processor_topology_node tree to the
- * cpu_topology array.
- */
-int __init parse_acpi_topology(void)
-{
-	unsigned int max_smt_thread_num = 1;
-	struct cpu_smt_info *entry;
-	struct xarray hetero_cpu;
-	unsigned long hetero_id;
-	int cpu, topology_id;
-
-	if (acpi_disabled)
-		return 0;
-
-	xa_init(&hetero_cpu);
-
-	for_each_possible_cpu(cpu) {
-		topology_id = find_acpi_cpu_topology(cpu, 0);
-		if (topology_id < 0)
-			return topology_id;
-
-		if (acpi_cpu_is_threaded(cpu)) {
-			cpu_topology[cpu].thread_id = topology_id;
-			topology_id = find_acpi_cpu_topology(cpu, 1);
-			cpu_topology[cpu].core_id   = topology_id;
-
-			/*
-			 * In the PPTT, CPUs below a node with the 'identical
-			 * implementation' flag have the same number of threads.
-			 * Count the number of threads for only one CPU (i.e.
-			 * one core_id) among those with the same hetero_id.
-			 * See the comment of find_acpi_cpu_topology_hetero_id()
-			 * for more details.
-			 *
-			 * One entry is created for each node having:
-			 * - the 'identical implementation' flag
-			 * - its parent not having the flag
-			 */
-			hetero_id = find_acpi_cpu_topology_hetero_id(cpu);
-			entry = xa_load(&hetero_cpu, hetero_id);
-			if (!entry) {
-				entry = kzalloc(sizeof(*entry), GFP_KERNEL);
-				WARN_ON_ONCE(!entry);
-
-				if (entry) {
-					entry->core_id = topology_id;
-					entry->thread_num = 1;
-					xa_store(&hetero_cpu, hetero_id,
-						 entry, GFP_KERNEL);
-				}
-			} else if (entry->core_id == topology_id) {
-				entry->thread_num++;
-			}
-		} else {
-			cpu_topology[cpu].thread_id  = -1;
-			cpu_topology[cpu].core_id    = topology_id;
-		}
-		topology_id = find_acpi_cpu_topology_cluster(cpu);
-		cpu_topology[cpu].cluster_id = topology_id;
-		topology_id = find_acpi_cpu_topology_package(cpu);
-		cpu_topology[cpu].package_id = topology_id;
-	}
-
-	/*
-	 * This is a short loop since the number of XArray elements is the
-	 * number of heterogeneous CPU clusters. On a homogeneous system
-	 * there's only one entry in the XArray.
-	 */
-	xa_for_each(&hetero_cpu, hetero_id, entry) {
-		max_smt_thread_num = max(max_smt_thread_num, entry->thread_num);
-		xa_erase(&hetero_cpu, hetero_id);
-		kfree(entry);
-	}
-
-	cpu_smt_set_num_threads(max_smt_thread_num, max_smt_thread_num);
-	xa_destroy(&hetero_cpu);
-	return 0;
-}
-#endif
-
 #ifdef CONFIG_ARM64_AMU_EXTN
 #define read_corecnt()	read_sysreg_s(SYS_AMEVCNTR0_CORE_EL0)
 #define read_constcnt()	read_sysreg_s(SYS_AMEVCNTR0_CONST_EL0)

drivers/base/arch_topology.c

···
 	clear_cpu_topology(cpu);
 }
 
+#if defined(CONFIG_ARM64) || defined(CONFIG_RISCV)
+struct cpu_smt_info {
+	unsigned int thread_num;
+	int core_id;
+};
+
+static bool __init acpi_cpu_is_threaded(int cpu)
+{
+	int is_threaded = acpi_pptt_cpu_is_thread(cpu);
+
+	/*
+	 * if the PPTT doesn't have thread information, check for architecture
+	 * specific fallback if available
+	 */
+	if (is_threaded < 0)
+		is_threaded = arch_cpu_is_threaded();
+
+	return !!is_threaded;
+}
+
+/*
+ * Propagate the topology information of the processor_topology_node tree to the
+ * cpu_topology array.
+ */
 __weak int __init parse_acpi_topology(void)
 {
+	unsigned int max_smt_thread_num = 1;
+	struct cpu_smt_info *entry;
+	struct xarray hetero_cpu;
+	unsigned long hetero_id;
+	int cpu, topology_id;
+
+	if (acpi_disabled)
+		return 0;
+
+	xa_init(&hetero_cpu);
+
+	for_each_possible_cpu(cpu) {
+		topology_id = find_acpi_cpu_topology(cpu, 0);
+		if (topology_id < 0)
+			return topology_id;
+
+		if (acpi_cpu_is_threaded(cpu)) {
+			cpu_topology[cpu].thread_id = topology_id;
+			topology_id = find_acpi_cpu_topology(cpu, 1);
+			cpu_topology[cpu].core_id   = topology_id;
+
+			/*
+			 * In the PPTT, CPUs below a node with the 'identical
+			 * implementation' flag have the same number of threads.
+			 * Count the number of threads for only one CPU (i.e.
+			 * one core_id) among those with the same hetero_id.
+			 * See the comment of find_acpi_cpu_topology_hetero_id()
+			 * for more details.
+			 *
+			 * One entry is created for each node having:
+			 * - the 'identical implementation' flag
+			 * - its parent not having the flag
+			 */
+			hetero_id = find_acpi_cpu_topology_hetero_id(cpu);
+			entry = xa_load(&hetero_cpu, hetero_id);
+			if (!entry) {
+				entry = kzalloc(sizeof(*entry), GFP_KERNEL);
+				WARN_ON_ONCE(!entry);
+
+				if (entry) {
+					entry->core_id = topology_id;
+					entry->thread_num = 1;
+					xa_store(&hetero_cpu, hetero_id,
+						 entry, GFP_KERNEL);
+				}
+			} else if (entry->core_id == topology_id) {
+				entry->thread_num++;
+			}
+		} else {
+			cpu_topology[cpu].thread_id  = -1;
+			cpu_topology[cpu].core_id    = topology_id;
+		}
+		topology_id = find_acpi_cpu_topology_cluster(cpu);
+		cpu_topology[cpu].cluster_id = topology_id;
+		topology_id = find_acpi_cpu_topology_package(cpu);
+		cpu_topology[cpu].package_id = topology_id;
+	}
+
+	/*
+	 * This is a short loop since the number of XArray elements is the
+	 * number of heterogeneous CPU clusters. On a homogeneous system
+	 * there's only one entry in the XArray.
+	 */
+	xa_for_each(&hetero_cpu, hetero_id, entry) {
+		max_smt_thread_num = max(max_smt_thread_num, entry->thread_num);
+		xa_erase(&hetero_cpu, hetero_id);
+		kfree(entry);
+	}
+
+	cpu_smt_set_num_threads(max_smt_thread_num, max_smt_thread_num);
+	xa_destroy(&hetero_cpu);
 	return 0;
 }
 
-#if defined(CONFIG_ARM64) || defined(CONFIG_RISCV)
 void __init init_cpu_topology(void)
 {
 	int cpu, ret;

include/linux/arch_topology.h

···
 #define topology_sibling_cpumask(cpu)	(&cpu_topology[cpu].thread_sibling)
 #define topology_cluster_cpumask(cpu)	(&cpu_topology[cpu].cluster_sibling)
 #define topology_llc_cpumask(cpu)	(&cpu_topology[cpu].llc_sibling)
+
+#ifndef arch_cpu_is_threaded
+#define arch_cpu_is_threaded()	(0)
+#endif
+
 void init_cpu_topology(void);
 void store_cpu_topology(unsigned int cpuid);
 const struct cpumask *cpu_coregroup_mask(int cpu);