ARM: mark Cortex-M3/M4/M7 based boards as deprecated

The Cortex-M3/M4/M7 cores were designed as a replacement for the earlier
ARM7TDMI and ARM9TDMI microarchitectures used in older microcontrollers.

At the moment, Linux can run these cores either when they are integrated
into a larger SoC, or as standalone microcontrollers. While there was
a lot of development work going into Cortex-M support from 2011 to 2016,
this largely stopped when it became clear that Zephyr and other RTOS
had taken over that market. To date, the only Cortex-M based based
microcontroller boards supported upstream are reference implementations.

Schedule these for removal after the next LTS kernel, so if any users
remain that want to update their kernels, they can stay on that
version for a few years before having to maintain the platform support
out of tree.

Acked-by: Vladimir Zapolskiy <vz@mleia.com> # NXP LPC18xx/LPC43xx
Acked-by: Vladimir Murzin <vladimir.murzin@arm.com> # MPS2
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Acked-by: Frank Li <Frank.Li@nxp.com> # i.MX
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

arch/arm/Kconfig

@@ -471,7 +471,7 @@ source "arch/arm/mach-zynq/Kconfig"
 
 # ARMv7-M architecture
 config ARCH_LPC18XX
-	bool "NXP LPC18xx/LPC43xx"
+	bool "NXP LPC18xx/LPC43xx (DEPRECATED)"
 	depends on ARM_SINGLE_ARMV7M
 	select ARCH_HAS_RESET_CONTROLLER
 	select ARM_AMBA
@@ -481,8 +481,10 @@ config ARCH_LPC18XX
 	  Support for NXP's LPC18xx Cortex-M3 and LPC43xx Cortex-M4
 	  high performance microcontrollers.
 
+	  This platform is scheduled for removal in early 2027
+
 config ARCH_MPS2
-	bool "ARM MPS2 platform"
+	bool "ARM MPS2 platform (DEPRECATED)"
 	depends on ARM_SINGLE_ARMV7M
 	select ARM_AMBA
 	select CLKSRC_MPS2
@@ -493,6 +495,8 @@ config ARCH_MPS2
 	  Please, note that depends which Application Note is used memory map
 	  for the platform may vary, so adjustment of RAM base might be needed.
 
+	  This platform is scheduled for removal in early 2027
+
 # Definitions to make life easier
 config ARCH_ACORN
 	bool

arch/arm/mach-at91/Kconfig

@@ -15,13 +15,15 @@ menuconfig ARCH_AT91
 
 if ARCH_AT91
 config SOC_SAMV7
-	bool "SAM Cortex-M7 family" if ARM_SINGLE_ARMV7M
+	bool "SAM Cortex-M7 family (DEPRECATED)" if ARM_SINGLE_ARMV7M
 	select COMMON_CLK_AT91
 	select PINCTRL_AT91
 	help
 	  Select this if you are using an SoC from Microchip's SAME7, SAMS7 or SAMV7
 	  families.
 
+	  This platform is scheduled for removal in early 2027
+
 config SOC_SAMA5D2
 	bool "SAMA5D2 family"
 	depends on ARCH_MULTI_V7

arch/arm/mach-imx/Kconfig

@@ -219,12 +219,14 @@ config SOC_IMX7ULP
 	  This enables support for Freescale i.MX7 Ultra Low Power processor.
 
 config SOC_IMXRT
-	bool "i.MXRT support"
+	bool "i.MXRT support (DEPRECATED)"
 	depends on ARM_SINGLE_ARMV7M
 	select ARMV7M_SYSTICK if ARM_SINGLE_ARMV7M
 	help
 	  This enables support for Freescale i.MXRT Crossover processor.
 
+	  This platform is scheduled for removal in early 2027
+
 config SOC_VF610
 	bool "Vybrid Family VF610 support"
 	select ARM_GIC if ARCH_MULTI_V7

arch/arm/mach-stm32/Kconfig

@@ -14,30 +14,32 @@ menuconfig ARCH_STM32
 	select STM32_EXTI if ARM_SINGLE_ARMV7M
 	select STM32_FIREWALL
 	help
-	  Support for STMicroelectronics STM32 processors.
+	  Support for STMicroelectronics STM32MP1 processors using Cortex-A7
+	  cores. Note that support for the earlier Cortex-M based variants
+	  is deprecated and scheduled for removal in early 2027.
 
 if ARCH_STM32
 
 if ARM_SINGLE_ARMV7M
 
 config MACH_STM32F429
-	bool "STMicroelectronics STM32F429"
+	bool "STMicroelectronics STM32F429 (DEPRECATED)"
 	default y
 
 config MACH_STM32F469
-	bool "STMicroelectronics STM32F469"
+	bool "STMicroelectronics STM32F469 (DEPRECATED)"
 	default y
 
 config MACH_STM32F746
-	bool "STMicroelectronics STM32F746"
+	bool "STMicroelectronics STM32F746 (DEPRECATED)"
 	default y
 
 config MACH_STM32F769
-	bool "STMicroelectronics STM32F769"
+	bool "STMicroelectronics STM32F769 (DEPRECATED)"
 	default y
 
 config MACH_STM32H743
-	bool "STMicroelectronics STM32H743"
+	bool "STMicroelectronics STM32H743 (DEPRECATED)"
 	default y
 
 endif # ARMv7-M