MIPS: Loongson: Set Loongson32 to MIPS32R1

LS232 (Loonson 2-issue 32-bit, also called GS232 (Godson 2-issue 32-bit))
is the CPU core (microarchitecture) of Loongson 1A/1B/1C.

According to "LS232 用户手册 (LS232 User Manual)", LS232 implements the
MIPS32 Release 1 instruction set, and part of the MIPS32 Release 2
instruction set.

In the manual, LS232 implements all of the MIPS32R2 instruction set
except the FPU instructions, and LS232 also implements 5 FPU
instructions of the MIPS32R2 instruction set: CEIL.L.fmt, CVT.L.fmt,
FLOOR.L.fmt, TRUNC.L.fmt, and ROUND.L.fmt.

But a bug of the DI instruction has been found during tests, the DI
instruction can not disable interrupts in arch_local_irq_disable() with
CONFIG_PREEMPT_NONE=y and CFLAGS='-mno-branch-likely' in some cases.

[paul.burton@mips.com:
  - Remove the _MIPS_ISA redefinition to match the change made for the
    generic MIPSr1 CPUs by commit 344ebf09949c ("MIPS: Always use
    -march=<arch>, not -<arch> shortcuts").]

Signed-off-by: 谢致邦 (XIE Zhibang) <Yeking@Red54.com>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Patchwork: https://patchwork.linux-mips.org/patch/16155/
Cc: linux-mips@linux-mips.org
Cc: ralf@linux-mips.org

arch/mips/Kconfig

@@ -1424,7 +1424,8 @@ config CPU_LOONGSON1B
 	select LEDS_GPIO_REGISTER
 	help
 	  The Loongson 1B is a 32-bit SoC, which implements the MIPS32
-	  release 2 instruction set.
+	  Release 1 instruction set and part of the MIPS32 Release 2
+	  instruction set.
 
 config CPU_LOONGSON1C
 	bool "Loongson 1C"
@@ -1433,7 +1434,8 @@ config CPU_LOONGSON1C
 	select LEDS_GPIO_REGISTER
 	help
 	  The Loongson 1C is a 32-bit SoC, which implements the MIPS32
-	  release 2 instruction set.
+	  Release 1 instruction set and part of the MIPS32 Release 2
+	  instruction set.
 
 config CPU_MIPS32_R1
 	bool "MIPS32 Release 1"
@@ -1833,7 +1835,7 @@ config CPU_LOONGSON2
 config CPU_LOONGSON1
 	bool
 	select CPU_MIPS32
-	select CPU_MIPSR2
+	select CPU_MIPSR1
 	select CPU_HAS_PREFETCH
 	select CPU_SUPPORTS_32BIT_KERNEL
 	select CPU_SUPPORTS_HIGHMEM

arch/mips/loongson32/Platform

@@ -1,7 +1,4 @@
-cflags-$(CONFIG_CPU_LOONGSON1)	+= \
-	$(call cc-option,-march=mips32r2,-mips32r2 -U_MIPS_ISA -D_MIPS_ISA=_MIPS_ISA_MIPS32) \
-	-Wa,-mips32r2 -Wa,--trap
-
+cflags-$(CONFIG_CPU_LOONGSON1)		+= -march=mips32 -Wa,--trap
 platform-$(CONFIG_MACH_LOONGSON32)	+= loongson32/
 cflags-$(CONFIG_MACH_LOONGSON32)	+= -I$(srctree)/arch/mips/include/asm/mach-loongson32
 load-$(CONFIG_LOONGSON1_LS1B)		+= 0xffffffff80100000