ARM: move -march=* and -mtune= options to arch/arm/Makefile

My main motivations for this commit are:

[1] Follow the arch/arm/Makefile style of Linux Kernel

[2] Maintain compiler options systematically
  Currently, we give -march=* and -mtune=* options inconsistently:
  Only some of the CPUs pass -march=* and -mtune=* options.
  By collecting such options into the single place arch/arm/Makefile
  we can tell which options are missing at a glance.

[3] Prepare for deprecating arch/*/cpu/*/config.mk

Note:
  This commit just moves the compiler options so as not to change
  the behavior at all.  It does not care about the correctness of
  the given options.  Fox example, "-march=armv5te" might be better
  than "-march=armv4" for ARM946EJS, but it is beyond the scope this
  commit.  Also, filling the missing -march=* and -tune=* is left
  to follow-up patches.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Acked-by: Marek Vasut <marex@denx.de>
Acked-by: Stefan Roese <sr@denx.de>

arch/arm/Makefile

@@ -2,6 +2,38 @@
 # SPDX-License-Identifier:	GPL-2.0+
 #
 
+# This selects which instruction set is used.
+arch-$(CONFIG_CPU_ARM720T)	=-march=armv4
+arch-$(CONFIG_CPU_ARM920T)	=-march=armv4
+arch-$(CONFIG_CPU_ARM926EJS)	=-march=armv5te
+arch-$(CONFIG_CPU_ARM946ES)	=-march=armv4
+arch-$(CONFIG_CPU_SA1100)	=-march=armv4
+arch-$(CONFIG_CPU_PXA)		=
+arch-$(CONFIG_CPU_ARM1136)	=-march=armv5
+arch-$(CONFIG_CPU_ARM1176)	=-march=armv5t
+arch-$(CONFIG_CPU_V7)		=$(call cc-option, -march=armv7-a, -march=armv5)
+arch-$(CONFIG_ARM64)		=-march=armv8-a
+
+# Evaluate arch cc-option calls now
+arch-y := $(arch-y)
+
+# This selects how we optimise for the processor.
+tune-$(CONFIG_CPU_ARM720T)	=-mtune=arm7tdmi
+tune-$(CONFIG_CPU_ARM920T)	=
+tune-$(CONFIG_CPU_ARM926EJS)	=
+tune-$(CONFIG_CPU_ARM946ES)	=
+tune-$(CONFIG_CPU_SA1100)	=-mtune=strongarm1100
+tune-$(CONFIG_CPU_PXA)		=-mcpu=xscale
+tune-$(CONFIG_CPU_ARM1136)	=
+tune-$(CONFIG_CPU_ARM1176)	=
+tune-$(CONFIG_CPU_V7)		=
+tune-$(CONFIG_ARM64)		=
+
+# Evaluate tune cc-option calls now
+tune-y := $(tune-y)
+
+PLATFORM_CPPFLAGS += $(arch-y) $(tune-y)
+
 # Machine directory name.  This list is sorted alphanumerically
 # by CONFIG_* macro name.
 machine-$(CONFIG_ARCH_AT91)		+= at91

arch/arm/cpu/arm1136/config.mk

@@ -1,9 +0,0 @@
-#
-# (C) Copyright 2002
-# Gary Jennejohn, DENX Software Engineering, <garyj@denx.de>
-#
-# SPDX-License-Identifier:	GPL-2.0+
-#
-
-# Make ARMv5 to allow more compilers to work, even though its v6.
-PLATFORM_CPPFLAGS += -march=armv5

arch/arm/cpu/arm1176/config.mk

@@ -1,9 +0,0 @@
-#
-# (C) Copyright 2002
-# Gary Jennejohn, DENX Software Engineering, <garyj@denx.de>
-#
-# SPDX-License-Identifier:	GPL-2.0+
-#
-
-# Make ARMv5 to allow more compilers to work, even though its v6.
-PLATFORM_CPPFLAGS += -march=armv5t

arch/arm/cpu/arm720t/config.mk

@@ -1,9 +0,0 @@
-#
-# (C) Copyright 2002
-# Sysgo Real-Time Solutions, GmbH <www.elinos.com>
-# Marius Groeger <mgroeger@sysgo.de>
-#
-# SPDX-License-Identifier:	GPL-2.0+
-#
-
-PLATFORM_CPPFLAGS += -march=armv4 -mtune=arm7tdmi

arch/arm/cpu/arm920t/config.mk

@@ -1,8 +0,0 @@
-#
-# (C) Copyright 2002
-# Gary Jennejohn, DENX Software Engineering, <garyj@denx.de>
-#
-# SPDX-License-Identifier:	GPL-2.0+
-#
-
-PLATFORM_CPPFLAGS += -march=armv4

arch/arm/cpu/arm926ejs/config.mk

@@ -1,8 +0,0 @@
-#
-# (C) Copyright 2002
-# Gary Jennejohn, DENX Software Engineering, <garyj@denx.de>
-#
-# SPDX-License-Identifier:	GPL-2.0+
-#
-
-PLATFORM_CPPFLAGS += -march=armv5te

arch/arm/cpu/arm946es/config.mk

@@ -1,8 +0,0 @@
-#
-# (C) Copyright 2002
-# Gary Jennejohn, DENX Software Engineering, <garyj@denx.de>
-#
-# SPDX-License-Identifier:	GPL-2.0+
-#
-
-PLATFORM_CPPFLAGS +=  -march=armv4

arch/arm/cpu/armv7/config.mk

@@ -5,11 +5,6 @@
 # SPDX-License-Identifier:	GPL-2.0+
 #
 
-# If armv7-a is not supported by GCC fall-back to armv5, which is
-# supported by more tool-chains
-PF_CPPFLAGS_ARMV7 := $(call cc-option, -march=armv7-a, -march=armv5)
-PLATFORM_CPPFLAGS += $(PF_CPPFLAGS_ARMV7)
-
 # On supported platforms we set the bit which causes us to trap on unaligned
 # memory access.  This is the opposite of what the compiler expects to be
 # the default so we must pass in -mno-unaligned-access so that it is aware

arch/arm/cpu/armv8/config.mk

@@ -6,7 +6,5 @@
 #
 PLATFORM_RELFLAGS += -fno-common -ffixed-x18
 
-PF_CPPFLAGS_ARMV8 := $(call cc-option, -march=armv8-a)
 PF_NO_UNALIGNED := $(call cc-option, -mstrict-align)
-PLATFORM_CPPFLAGS += $(PF_CPPFLAGS_ARMV8)
 PLATFORM_CPPFLAGS += $(PF_NO_UNALIGNED)

arch/arm/cpu/pxa/config.mk

@@ -6,8 +6,6 @@
 # SPDX-License-Identifier:	GPL-2.0+
 #
 
-PLATFORM_CPPFLAGS += -mcpu=xscale
-
 #
 # !WARNING!
 # The PXA's OneNAND SPL uses .text.0 and .text.1 segments to allow booting from

arch/arm/cpu/sa1100/config.mk

@@ -1,9 +0,0 @@
-#
-# (C) Copyright 2002
-# Sysgo Real-Time Solutions, GmbH <www.elinos.com>
-# Marius Groeger <mgroeger@sysgo.de>
-#
-# SPDX-License-Identifier:	GPL-2.0+
-#
-
-PLATFORM_CPPFLAGS += -march=armv4 -mtune=strongarm1100