arch/riscv: add cluster local hartid

Some multicore RV chips (mpfs, jh7110 etc) have hart clusters
and globally numbered mhartids. Clusters with single hart or
SMP support can be managed by one NuttX instance. Currently
NuttX expects to use cluster-local ids.

This allows us to get local ids by offsetting mhartids with a
base value.

Note that there are chips (e.g. k230) that use cluster-local
ids directly, so this is not needed for them.

Signed-off-by: Yanfeng Liu <yfliu2008@qq.com>

arch/risc-v/Kconfig

@@ -451,6 +451,20 @@ config ARCH_RV_MMIO_BITS
 	default 32 if ARCH_RV32
 	default 64 if ARCH_RV64
 
+config ARCH_RV_HARTID_BASE
+	int "Base hartid of this cluster"
+	default 0
+	---help---
+		Some RV chips have multiple cluster of harts with
+		globally numbered mhartids, like qemu-rv, mpfs and
+		jh7110 etc.  Clusters with SMP ability can be managed
+		by NuttX. As NuttX expects cluster-local hart ids,
+		we can shift mhartid by this value to derive such
+		local ids. The SMP_NCPUS still defines number of
+		harts in the cluster. Note that we assume that global
+		ids for each cluster are continuous. Note that there
+		are chips like k230 which don't have global mhartid.
+
 config ARCH_FAMILY
 	string
 	default "rv32" if ARCH_RV32

arch/risc-v/src/common/riscv_macros.S

@@ -362,6 +362,9 @@
   REGLOAD \out, RISCV_PERCPU_HARTID(\out)
 #else
   csrr    \out, CSR_MHARTID
+#  if CONFIG_ARCH_RV_HARTID_BASE > 0
+  add    \out, \out, - CONFIG_ARCH_RV_HARTID_BASE
+#  endif
 #endif
 .endm