[PATCH v1 1/2] RISC-V: move zicsr/zifencei spec version check to Kconfig

[Conor Dooley <conor@kernel.org>]

From: Conor Dooley <conor.dooley@microchip.com>

Checking whether binutils defaults to using a version of the spec
requiring zicsr/zifencei being done in our Makefile is functionally
sufficient at present, but makes it harder to tell after the fact
which extensions are enabled.
By moving it to Kconfig, it's easy to tell from standard build artifacts
what has been done & the road is paved for dealing with this differently
for both binutils and LLVM.

Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
---
 arch/riscv/Kconfig  | 10 ++++++++++
 arch/riscv/Makefile |  5 +----
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index cebf0c5f8824..4eb0ef8314b3 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -288,6 +288,16 @@ config ARCH_RV64I
 
 endchoice
 
+config TOOLCHAIN_NEEDS_SPEC_20191213
+	bool
+	default y
+	depends on !64BIT || $(cc-option,-mabi=lp64 -march=rv64ima_zicsr_zifencei)
+	depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32ima_zicsr_zifencei)
+	help
+	  Newer binutils versions default to ISA spec version 20191213 which
+	  moves some instructions from the I extension to the Zicsr and Zifencei
+	  extensions.
+
 # We must be able to map all physical memory into the kernel, but the compiler
 # is still a bit more efficient when generating code if it's setup in a manner
 # such that it can only map 2GiB of memory.
diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
index 12d91b0a73d8..7e1267b0e73f 100644
--- a/arch/riscv/Makefile
+++ b/arch/riscv/Makefile
@@ -53,10 +53,7 @@ riscv-march-$(CONFIG_ARCH_RV64I)	:= rv64ima
 riscv-march-$(CONFIG_FPU)		:= $(riscv-march-y)fd
 riscv-march-$(CONFIG_RISCV_ISA_C)	:= $(riscv-march-y)c
 
-# Newer binutils versions default to ISA spec version 20191213 which moves some
-# instructions from the I extension to the Zicsr and Zifencei extensions.
-toolchain-need-zicsr-zifencei := $(call cc-option-yn, -march=$(riscv-march-y)_zicsr_zifencei)
-riscv-march-$(toolchain-need-zicsr-zifencei) := $(riscv-march-y)_zicsr_zifencei
+riscv-march-$(CONFIG_TOOLCHAIN_NEEDS_SPEC_20191213) := $(riscv-march-y)_zicsr_zifencei
 
 # Check if the toolchain supports Zicbom extension
 riscv-march-$(CONFIG_TOOLCHAIN_HAS_ZICBOM) := $(riscv-march-y)_zicbom
-- 
2.39.1