MIPS: Use Kconfig to select CPU_NO_EFFICIENT_FFS
Select CONFIG_CPU_NO_EFFICIENT_FFS via Kconfig when the kernel is
configured for a pre-MIPS32r1 CPU, rather than defining its equivalent
in asm/cpu-features.h based upon overrides of cpu_has_mips* macros.
The latter only works if a platform has an cpu-feature-overrides.h
header which defines cpu_has_mips* macros, which are not generally
needed. There are many cases where we know that the target ISA for a
kernel build is MIPS32r1 or later & thus includes the CLZ instruction,
without requiring any overrides from the platform. Using Kconfig allows
us to take those into account, and more naturally make a decision about
instruction support using information about the target ISA.
Signed-off-by: Paul Burton <paul.burton@mips.com>
Patchwork: https://patchwork.linux-mips.org/patch/21045/
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Zhaoxiu Zeng <zhaoxiu.zeng@gmail.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 513a9c8..6eb17b4 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -15,6 +15,7 @@
select ARCH_WANT_IPC_PARSE_VERSION
select BUILDTIME_EXTABLE_SORT
select CLONE_BACKWARDS
+ select CPU_NO_EFFICIENT_FFS if (TARGET_ISA_REV < 1)
select CPU_PM if CPU_IDLE
select DMA_DIRECT_OPS
select GENERIC_ATOMIC64 if !64BIT
@@ -2031,7 +2032,7 @@
default y if CPU_MIPS64_R1 || CPU_MIPS64_R2 || CPU_MIPS64_R6
#
-# These two indicate the revision of the architecture, either Release 1 or Release 2
+# These indicate the revision of the architecture
#
config CPU_MIPSR1
bool
@@ -2052,6 +2053,16 @@
select MIPS_CRC_SUPPORT
select MIPS_SPRAM
+config TARGET_ISA_REV
+ int
+ default 1 if CPU_MIPSR1
+ default 2 if CPU_MIPSR2
+ default 6 if CPU_MIPSR6
+ default 0
+ help
+ Reflects the ISA revision being targeted by the kernel build. This
+ is effectively the Kconfig equivalent of MIPS_ISA_REV.
+
config EVA
bool