arch: arm: Add Cortex-R4 support

Pass the correct -march and -mcpu flags to the compiler when building
for the Cortex-R4.

Signed-off-by: Bradley Bolen <bbolen@lexmark.com>

arch/arm/CMakeLists.txt

@@ -7,6 +7,7 @@ set(ARCH_FOR_cortex-m4        armv7e-m        )
 set(ARCH_FOR_cortex-m23       armv8-m.base    )
 set(ARCH_FOR_cortex-m33       armv8-m.main+dsp)
 set(ARCH_FOR_cortex-m33+nodsp armv8-m.main    )
+set(ARCH_FOR_cortex-r4        armv7-r         )
 
 if(ARCH_FOR_${GCC_M_CPU})
     set(ARCH_FLAG -march=${ARCH_FOR_${GCC_M_CPU}})

arch/arm/core/cortex_r/Kconfig

@@ -14,6 +14,14 @@
 # if one selects a different ARM Cortex Family (Cortex-A or Cortex-M)
 
 
+config CPU_CORTEX_R4
+	bool
+	select CPU_CORTEX_R
+	select ARMV7_R
+	select ARMV7_R_FP if CPU_HAS_FPU
+	help
+	  This option signifies the use of a Cortex-R4 CPU
+
 if CPU_CORTEX_R
 
 config ARMV7_R

cmake/gcc-m-cpu.cmake

@@ -22,6 +22,8 @@ if("${ARCH}" STREQUAL "arm")
     else()
       set(GCC_M_CPU cortex-m33+nodsp)
     endif()
+  elseif(CONFIG_CPU_CORTEX_R4)
+    set(GCC_M_CPU cortex-r4)
   else()
     message(FATAL_ERROR "Expected CONFIG_CPU_CORTEX_x to be defined")
   endif()