xtensa: simplify addition of new core variants

Instead of adding new Kconfig options and Makefile rules for each new
core variant provide XTENSA_VARIANT_CUSTOM variant and record variant
name in the XTENSA_VARIANT_NAME variable. Adding new core variant now
means providing directory structure under arch/xtensa/variant and
specifying correct name in kernel configuration.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

arch/xtensa/Kconfig

@@ -62,7 +62,9 @@ config TRACE_IRQFLAGS_SUPPORT
 	def_bool y
 
 config MMU
-	def_bool n
+	bool
+	default n if !XTENSA_VARIANT_CUSTOM
+	default XTENSA_VARIANT_MMU if XTENSA_VARIANT_CUSTOM
 
 config VARIANT_IRQ_SWITCH
 	def_bool n
@@ -102,8 +104,40 @@ config XTENSA_VARIANT_S6000
 	select VARIANT_IRQ_SWITCH
 	select ARCH_REQUIRE_GPIOLIB
 	select XTENSA_CALIBRATE_CCOUNT
+
+config XTENSA_VARIANT_CUSTOM
+	bool "Custom Xtensa processor configuration"
+	select MAY_HAVE_SMP
+	select HAVE_XTENSA_GPIO32
+	help
+	  Select this variant to use a custom Xtensa processor configuration.
+	  You will be prompted for a processor variant CORENAME.
 endchoice
 
+config XTENSA_VARIANT_CUSTOM_NAME
+	string "Xtensa Processor Custom Core Variant Name"
+	depends on XTENSA_VARIANT_CUSTOM
+	help
+	  Provide the name of a custom Xtensa processor variant.
+	  This CORENAME selects arch/xtensa/variant/CORENAME.
+	  Dont forget you have to select MMU if you have one.
+
+config XTENSA_VARIANT_NAME
+	string
+	default "dc232b"			if XTENSA_VARIANT_DC232B
+	default "dc233c"			if XTENSA_VARIANT_DC233C
+	default "fsf"				if XTENSA_VARIANT_FSF
+	default "s6000"				if XTENSA_VARIANT_S6000
+	default XTENSA_VARIANT_CUSTOM_NAME	if XTENSA_VARIANT_CUSTOM
+
+config XTENSA_VARIANT_MMU
+	bool "Core variant has a Full MMU (TLB, Pages, Protection, etc)"
+	depends on XTENSA_VARIANT_CUSTOM
+	default y
+	help
+	  Build a Conventional Kernel with full MMU support,
+	  ie: it supports a TLB with auto-loading, page protection.
+
 config XTENSA_UNALIGNED_USER
 	bool "Unaligned memory access in use space"
 	help

arch/xtensa/Makefile

@@ -4,6 +4,7 @@
 # for more details.
 #
 # Copyright (C) 2001 - 2005  Tensilica Inc.
+# Copyright (C) 2014 Cadence Design Systems Inc.
 #
 # This file is included by the global makefile so that you can add your own
 # architecture-specific flags and dependencies. Remember to do have actions
@@ -13,11 +14,7 @@
 # Core configuration.
 # (Use VAR=<xtensa_config> to use another default compiler.)
 
-variant-$(CONFIG_XTENSA_VARIANT_FSF)		:= fsf
-variant-$(CONFIG_XTENSA_VARIANT_DC232B)		:= dc232b
-variant-$(CONFIG_XTENSA_VARIANT_DC233C)		:= dc233c
-variant-$(CONFIG_XTENSA_VARIANT_S6000)		:= s6000
-variant-$(CONFIG_XTENSA_VARIANT_LINUX_CUSTOM)	:= custom
+variant-y := $(patsubst "%",%,$(CONFIG_XTENSA_VARIANT_NAME))
 
 VARIANT = $(variant-y)
 export VARIANT