rules.h: Add ENV_ macros to detect current architecture

This patch expands the existing ENV_<stage> macros in <rules.h> with a
set of ENV_<arch> macros which can be used to detect which architecture
the current compilation unit is built for. These are more consistent
than compiler-defined macros (like '#ifdef __arm__') and will make it
easier to write small, architecture-dependent differences in common code
(where we currently often use IS_ENABLED(CONFIG_ARCH_...), which is
technically incorrect in a world where every stage can run on a
different architecture, and merely kinda happened to work out for now).

Also remove a vestigal <arch/rules.h> from ARM64 which was no longer
used, and genericise ARM subarchitecture Makefiles a little to make
things like __COREBOOT_ARM_ARCH__ available from all file types
(including .ld).

BUG=None
TEST=Compiled Falco, Blaze, Jerry and Smaug.

Change-Id: Id51aeb290b5c215c653e42a51919d0838e28621f
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: http://review.coreboot.org/12433
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Tested-by: Raptor Engineering Automated Test Stand <noreply@raptorengineeringinc.com>

src/include/rules.h

@@ -94,4 +94,104 @@
 #define __SIMPLE_DEVICE__
 #endif
 
+/* Define helpers about the current architecture, based on toolchain.inc. */
+
+#if defined(__ARCH_arm__)
+#define ENV_ARM 1
+#define ENV_ARM64 0
+#if __COREBOOT_ARM_ARCH__ == 4
+#define ENV_ARMV4 1
+#define ENV_ARMV7 0
+#elif __COREBOOT_ARM_ARCH__ == 7
+#define ENV_ARMV4 0
+#define ENV_ARMV7 1
+#else
+#define ENV_ARMV4 0
+#define ENV_ARMV7 0
+#endif
+#define ENV_ARMV8 0
+#define ENV_MIPS 0
+#define ENV_RISCV 0
+#define ENV_X86 0
+#define ENV_X86_32 0
+#define ENV_X86_64 0
+
+#elif defined(__ARCH_arm64__)
+#define ENV_ARM 0
+#define ENV_ARM64 1
+#define ENV_ARMV4 0
+#define ENV_ARMV7 0
+#if __COREBOOT_ARM_ARCH__ == 8
+#define ENV_ARMV8 1
+#else
+#define ENV_ARMV8 0
+#endif
+#define ENV_MIPS 0
+#define ENV_RISCV 0
+#define ENV_X86 0
+#define ENV_X86_32 0
+#define ENV_X86_64 0
+
+#elif defined(__ARCH_mips__)
+#define ENV_ARM 0
+#define ENV_ARM64 0
+#define ENV_ARMV4 0
+#define ENV_ARMV7 0
+#define ENV_ARMV8 0
+#define ENV_MIPS 1
+#define ENV_RISCV 0
+#define ENV_X86 0
+#define ENV_X86_32 0
+#define ENV_X86_64 0
+
+#elif defined(__ARCH_riscv__)
+#define ENV_ARM 0
+#define ENV_ARM64 0
+#define ENV_ARMV4 0
+#define ENV_ARMV7 0
+#define ENV_ARMV8 0
+#define ENV_MIPS 0
+#define ENV_RISCV 1
+#define ENV_X86 0
+#define ENV_X86_32 0
+#define ENV_X86_64 0
+
+#elif defined(__ARCH_x86_32__)
+#define ENV_ARM 0
+#define ENV_ARM64 0
+#define ENV_ARMV4 0
+#define ENV_ARMV7 0
+#define ENV_ARMV8 0
+#define ENV_MIPS 0
+#define ENV_RISCV 0
+#define ENV_X86 1
+#define ENV_X86_32 1
+#define ENV_X86_64 0
+
+#elif defined(__ARCH_x86_64__)
+#define ENV_ARM 0
+#define ENV_ARM64 0
+#define ENV_ARMV4 0
+#define ENV_ARMV7 0
+#define ENV_ARMV8 0
+#define ENV_MIPS 0
+#define ENV_RISCV 0
+#define ENV_X86 1
+#define ENV_X86_32 0
+#define ENV_X86_64 1
+
+#else
+#define ENV_ARM 0
+#define ENV_ARM64 0
+#define ENV_ARMV4 0
+#define ENV_ARMV7 0
+#define ENV_ARMV8 0
+#define ENV_MIPS 0
+#define ENV_RISCV 0
+#define ENV_X86 0
+#define ENV_X86_32 0
+#define ENV_X86_64 0
+
+#endif
+
 #endif /* _RULES_H */