ARM: l2x0/pl310: Refactor Kconfig to be more maintainable

Making CACHE_L2X0 depend on (huge list of MACH_ and ARCH_ configs)
is bothersome to maintain and likely to lead to merge conflicts.

This patch moves the knowledge of which platforms have a L2x0 or
PL310 cache controller to the individual machines.  To enable this,
a new MIGHT_HAVE_CACHE_L2X0 config option is introduced to allow
machines to indicate that they may have such a cache controller
independently of each other.

Boards/SoCs which cannot reliably operate without the L2 cache
controller support will need to select CACHE_L2X0 directly from
their own Kconfigs instead.  This applies to some TrustZone-enabled
boards where Linux runs in the Normal World, for example.
Signed-off-by: Dave Martin <dave.martin@linaro.org>
Acked-by: Anton Vorontsov <cbouatmailru@gmail.com>
        (for cns3xxx)
Acked-by: Tony Lindgren <tony@atomide.com>
        (for omap)
Acked-by: Shawn Guo <shawn.guo@linaro.org>
        (for imx)
Acked-by: Kukjin Kim <kgene.kim@samsung.com>
        (for exynos)
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
        (for imx)
Acked-by: Olof Johansson <olof@lixom.net>
        (for tegra)

arch/arm/Kconfig

@@ -344,6 +344,7 @@ config ARCH_HIGHBANK
 	select CPU_V7
 	select GENERIC_CLOCKEVENTS
 	select HAVE_ARM_SCU
+	select MIGHT_HAVE_CACHE_L2X0
 	select USE_OF
 	help
 	  Support for the Calxeda Highbank SoC based boards.
@@ -361,6 +362,7 @@ config ARCH_CNS3XXX
 	select CPU_V6K
 	select GENERIC_CLOCKEVENTS
 	select ARM_GIC
+	select MIGHT_HAVE_CACHE_L2X0
 	select MIGHT_HAVE_PCI
 	select PCI_DOMAINS if PCI
 	help
@@ -381,6 +383,7 @@ config ARCH_PRIMA2
 	select GENERIC_CLOCKEVENTS
 	select CLKDEV_LOOKUP
 	select GENERIC_IRQ_CHIP
+	select MIGHT_HAVE_CACHE_L2X0
 	select USE_OF
 	select ZONE_DMA
 	help
@@ -633,6 +636,7 @@ config ARCH_TEGRA
 	select GENERIC_GPIO
 	select HAVE_CLK
 	select HAVE_SCHED_CLOCK
+	select MIGHT_HAVE_CACHE_L2X0
 	select ARCH_HAS_CPUFREQ
 	help
 	  This enables support for NVIDIA Tegra based systems (Tegra APX,
@@ -703,6 +707,7 @@ config ARCH_SHMOBILE
 	select CLKDEV_LOOKUP
 	select HAVE_MACH_CLKDEV
 	select GENERIC_CLOCKEVENTS
+	select MIGHT_HAVE_CACHE_L2X0
 	select NO_IOPORT
 	select SPARSE_IRQ
 	select MULTI_IRQ_HANDLER
@@ -904,6 +909,7 @@ config ARCH_U8500
 	select CLKDEV_LOOKUP
 	select ARCH_REQUIRE_GPIOLIB
 	select ARCH_HAS_CPUFREQ
+	select MIGHT_HAVE_CACHE_L2X0
 	help
 	  Support for ST-Ericsson's Ux500 architecture
 
@@ -914,6 +920,7 @@ config ARCH_NOMADIK
 	select CPU_ARM926T
 	select CLKDEV_LOOKUP
 	select GENERIC_CLOCKEVENTS
+	select MIGHT_HAVE_CACHE_L2X0
 	select ARCH_REQUIRE_GPIOLIB
 	help
 	  Support for the Nomadik platform by ST-Ericsson
@@ -973,6 +980,7 @@ config ARCH_ZYNQ
 	select ARM_GIC
 	select ARM_AMBA
 	select ICST
+	select MIGHT_HAVE_CACHE_L2X0
 	select USE_OF
 	help
 	  Support for Xilinx Zynq ARM Cortex A9 Platform

arch/arm/mach-exynos/Kconfig

@@ -17,6 +17,7 @@ choice
 
 config ARCH_EXYNOS4
 	bool "SAMSUNG EXYNOS4"
+	select MIGHT_HAVE_CACHE_L2X0
 	help
 	  Samsung EXYNOS4 SoCs based systems
 

arch/arm/mach-omap2/Kconfig

@@ -44,6 +44,7 @@ config ARCH_OMAP4
 	select CPU_V7
 	select ARM_GIC
 	select LOCAL_TIMERS if SMP
+	select MIGHT_HAVE_CACHE_L2X0
 	select PL310_ERRATA_588369
 	select PL310_ERRATA_727915
 	select ARM_ERRATA_720789

arch/arm/mach-realview/Kconfig

@@ -12,6 +12,7 @@ config REALVIEW_EB_A9MP
 	bool "Support Multicore Cortex-A9 Tile"
 	depends on MACH_REALVIEW_EB
 	select CPU_V7
+	select MIGHT_HAVE_CACHE_L2X0
 	help
 	  Enable support for the Cortex-A9MPCore tile fitted to the
 	  Realview(R) Emulation Baseboard platform.
@@ -21,6 +22,7 @@ config REALVIEW_EB_ARM11MP
 	depends on MACH_REALVIEW_EB
 	select CPU_V6K
 	select ARCH_HAS_BARRIERS if SMP
+	select MIGHT_HAVE_CACHE_L2X0
 	help
 	  Enable support for the ARM11MPCore tile fitted to the Realview(R)
 	  Emulation Baseboard platform.
@@ -39,6 +41,7 @@ config MACH_REALVIEW_PB11MP
 	select CPU_V6K
 	select ARM_GIC
 	select HAVE_PATA_PLATFORM
+	select MIGHT_HAVE_CACHE_L2X0
 	select ARCH_HAS_BARRIERS if SMP
 	help
 	  Include support for the ARM(R) RealView(R) Platform Baseboard for
@@ -51,6 +54,7 @@ config MACH_REALVIEW_PB1176
 	select CPU_V6
 	select ARM_GIC
 	select HAVE_TCM
+	select MIGHT_HAVE_CACHE_L2X0
 	help
 	  Include support for the ARM(R) RealView(R) Platform Baseboard for
 	  ARM1176JZF-S.
@@ -78,6 +82,7 @@ config MACH_REALVIEW_PBX
 	bool "Support RealView(R) Platform Baseboard Explore"
 	select ARM_GIC
 	select HAVE_PATA_PLATFORM
+	select MIGHT_HAVE_CACHE_L2X0
 	select ARCH_SPARSEMEM_ENABLE if CPU_V7 && !REALVIEW_HIGH_PHYS_OFFSET
 	select ZONE_DMA if SPARSEMEM
 	help

arch/arm/mach-vexpress/Kconfig

@@ -8,5 +8,6 @@ config ARCH_VEXPRESS_CA9X4
 	select ARM_ERRATA_720789
 	select ARM_ERRATA_751472
 	select ARM_ERRATA_753970
+	select MIGHT_HAVE_CACHE_L2X0
 
 endmenu

arch/arm/mm/Kconfig

@@ -816,14 +816,23 @@ config CACHE_FEROCEON_L2_WRITETHROUGH
 	  Say Y here to use the Feroceon L2 cache in writethrough mode.
 	  Unless you specifically require this, say N for writeback mode.
 
+config MIGHT_HAVE_CACHE_L2X0
+	bool
+	help
+	  This option should be selected by machines which have a L2x0
+	  or PL310 cache controller, but where its use is optional.
+
+	  The only effect of this option is to make CACHE_L2X0 and
+	  related options available to the user for configuration.
+
+	  Boards or SoCs which always require the cache controller
+	  support to be present should select CACHE_L2X0 directly
+	  instead of this option, thus preventing the user from
+	  inadvertently configuring a broken kernel.
+
 config CACHE_L2X0
-	bool "Enable the L2x0 outer cache controller"
-	depends on REALVIEW_EB_ARM11MP || MACH_REALVIEW_PB11MP || MACH_REALVIEW_PB1176 || \
-		   REALVIEW_EB_A9MP || ARCH_IMX_V6_V7 || MACH_REALVIEW_PBX || \
-		   ARCH_NOMADIK || ARCH_OMAP4 || ARCH_EXYNOS4 || ARCH_TEGRA || \
-		   ARCH_U8500 || ARCH_VEXPRESS_CA9X4 || ARCH_SHMOBILE || \
-		   ARCH_PRIMA2 || ARCH_ZYNQ || ARCH_CNS3XXX || ARCH_HIGHBANK
-	default y
+	bool "Enable the L2x0 outer cache controller" if MIGHT_HAVE_CACHE_L2X0
+	default MIGHT_HAVE_CACHE_L2X0
 	select OUTER_CACHE
 	select OUTER_CACHE_SYNC
 	help

arch/arm/plat-mxc/Kconfig

@@ -20,6 +20,7 @@ config ARCH_IMX_V6_V7
 	bool "i.MX3, i.MX6"
 	select AUTO_ZRELADDR if !ZBOOT_ROM
 	select ARM_PATCH_PHYS_VIRT
+	select MIGHT_HAVE_CACHE_L2X0
 	help
 	  This enables support for systems based on the Freescale i.MX3 and i.MX6
 	  family.