riscv: export cpu/freq invariant to scheduler

RISC-V now manages CPU topology using arch_topology which provides
CPU capacity and frequency related interfaces to access the cpu/freq
invariant in possible heterogeneous or DVFS-enabled platforms.

Here adds topology.h file to export the arch_topology interfaces for
replacing the scheduler's constant-based cpu/freq invariant accounting.

Signed-off-by: Song Shuai <suagrfillet@gmail.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Ley Foon Tan <lftan@kernel.org>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230323123924.3032174-1-suagrfillet@gmail.com
[Palmer: Fix the whitespace issues.]
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

Author: Song Shuai

arch/riscv/include/asm/topology.h

@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_RISCV_TOPOLOGY_H
+#define _ASM_RISCV_TOPOLOGY_H
+
+#include <linux/arch_topology.h>
+
+/* Replace task scheduler's default frequency-invariant accounting */
+#define arch_scale_freq_tick	topology_scale_freq_tick
+#define arch_set_freq_scale	topology_set_freq_scale
+#define arch_scale_freq_capacity	topology_get_freq_scale
+#define arch_scale_freq_invariant	topology_scale_freq_invariant
+
+/* Replace task scheduler's default cpu-invariant accounting */
+#define arch_scale_cpu_capacity	topology_get_cpu_scale
+
+/* Enable topology flag updates */
+#define arch_update_cpu_topology	topology_update_cpu_topology
+
+#include <asm-generic/topology.h>
+#endif /* _ASM_RISCV_TOPOLOGY_H */