arm: v7R: Add initial support

The Cortex-R* processors are a mid-range CPUs for use in deeply-embedded,
real-time systems. It implements the ARMv7-R architecture, and includes
Thumb-2 technology for optimum code density and processing throughput.

Except for MPU(Memory Protection Unit) and few CP15 registers, most of the
features are compatible with v7 architecture. So,reuse the same armv7
folder and introduce a new config CPU_V7R in order to differentiate
from v7 based platforms.

Tested-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>

arch/arm/Kconfig

@@ -212,6 +212,11 @@ config CPU_V7M
 	select THUMB2_KERNEL
 	select SYS_CACHE_SHIFT_5
 
+config CPU_V7R
+	bool
+	select HAS_THUMB2
+	select SYS_CACHE_SHIFT_6
+
 config CPU_PXA
 	bool
 	select SYS_CACHE_SHIFT_5
@@ -230,6 +235,7 @@ config SYS_CPU
 	default "arm1136" if CPU_ARM1136
 	default "arm1176" if CPU_ARM1176
 	default "armv7" if CPU_V7A
+	default "armv7" if CPU_V7R
 	default "armv7m" if CPU_V7M
 	default "pxa" if CPU_PXA
 	default "sa1100" if CPU_SA1100
@@ -245,6 +251,7 @@ config SYS_ARM_ARCH
 	default 6 if CPU_ARM1176
 	default 7 if CPU_V7A
 	default 7 if CPU_V7M
+	default 7 if CPU_V7R
 	default 5 if CPU_PXA
 	default 4 if CPU_SA1100
 	default 8 if ARM64

arch/arm/Makefile

@@ -16,6 +16,7 @@ arch-$(CONFIG_CPU_ARM1136)	=-march=armv5
 arch-$(CONFIG_CPU_ARM1176)	=-march=armv5t
 arch-$(CONFIG_CPU_V7A)		=$(call cc-option, -march=armv7-a, \
 				 $(call cc-option, -march=armv7, -march=armv5))
+arch-$(CONFIG_CPU_V7R)		=-march=armv7-r
 arch-$(CONFIG_ARM64)		=-march=armv8-a
 
 # On Tegra systems we must build SPL for the armv4 core on the device
@@ -39,6 +40,7 @@ tune-$(CONFIG_CPU_PXA)		=-mcpu=xscale
 tune-$(CONFIG_CPU_ARM1136)	=
 tune-$(CONFIG_CPU_ARM1176)	=
 tune-$(CONFIG_CPU_V7A)		=
+tune-$(CONFIG_CPU_V7R)		=
 tune-$(CONFIG_ARM64)		=
 
 # Evaluate tune cc-option calls now

arch/arm/cpu/armv7/start.S

@@ -81,7 +81,9 @@ switch_to_hypervisor_ret:
 
 	/* the mask ROM code should have PLL and others stable */
 #ifndef CONFIG_SKIP_LOWLEVEL_INIT
+#ifdef CONFIG_CPU_V7A
 	bl	cpu_init_cp15
+#endif
 #ifndef CONFIG_SKIP_LOWLEVEL_INIT_ONLY
 	bl	cpu_init_crit
 #endif

cmd/Kconfig

@@ -1103,7 +1103,7 @@ config BOOTP_PXE_CLIENTARCH
 config BOOTP_VCI_STRING
 	string
 	depends on CMD_BOOTP
-	default "U-Boot.armv7" if CPU_V7A || CPU_V7M
+	default "U-Boot.armv7" if CPU_V7A || CPU_V7M || CPU_V7R
 	default "U-Boot.armv8" if ARM64
 	default "U-Boot.arm" if ARM
 	default "U-Boot"