More on Cache/MMU configuration

Enabling Snoop Control Unit (SCU)

From what I find here and from some more references, there is no separate control for enabling the SCU in Raspberry Pi 2. Since there is no official documentation available for this I have gone ahead assuming SCU is on by default.

 Conditionally setting up Pi 1 or 2

 There are only a few differences between the configurations required for the two. These are mostly in the initial cp15 controls. Otherwise, they both follow the same initialization method. The same memory configuration structure arm_cp15_start_mmu_config_table[] in mminit.c is used for both.
So to provide for bsp specific set up of controls I have added a function raspberrypi_setup_mmu_and_cache() to bspstarthooks.c . The value of BSP_IS_RPI2 helps determine whether bsp being used is Pi 1 or Pi 2. A value of 1 implies bsp is Pi 2. The required parts of code are conditionally compiled and then the controls are passed to bsp_memory_management_initialize() . 

Code

This is how the controls are set up for Pi 1 and 2 in raspberrypi_setup_mmu_and_cache() . 
 
#if (BSP_IS_RPI2 == 1)
  bsp_initial_mmu_ctrl_clear = ARM_CP15_CTRL_A;
  bsp_initial_mmu_ctrl_set = ARM_CP15_CTRL_AFE | ARM_CP15_CTRL_Z; 
#else
  bsp_initial_mmu_ctrl_clear = 0;
  bsp_initial_mmu_ctrl_set = ARM_CP15_CTRL_AFE | ARM_CP15_CTRL_S
                  | ARM_CP15_CTRL_XP; 
#endif


After the above set up initialization function is called

bsp_memory_management_initialize(
    bsp_initial_mmu_ctrl_set,
    bsp_initial_mmu_ctrl_clear
  );