armv8: New MMU setup code allowing to use 48+ bits PA/VA

This patch adds code which sets up 2-level page tables on ARM64 thus
extending available VA space. CPUs implementing 64k translation
granule are able to use direct PA-VA mapping of the whole 48 bit
address space.
It also adds the ability to reset the SCTRL register at the very beginning
of execution to avoid interference from stale mappings set up by early
firmware/loaders/etc.

Signed-off-by: Sergey Temerkhanov <s.temerkhanov@gmail.com>
Signed-off-by: Radha Mohan Chintakuntla <rchintakuntla@cavium.com>

doc/README.arm64

@@ -36,11 +36,34 @@ Notes
 6. CONFIG_ARM64 instead of CONFIG_ARMV8 is used to distinguish aarch64 and
    aarch32 specific codes.
 
+7. CONFIG_SYS_FULL_VA is used to enable 2-level page tables. For cores
+   supporting 64k pages it allows usage of full 48+ virtual/physical addresses
+
+   Enabling this option requires the following ones to be defined:
+       - CONFIG_SYS_MEM_MAP - an array of 'struct mm_region' describing the
+         system memory map (start, length, attributes)
+       - CONFIG_SYS_MEM_MAP_SIZE - number of entries in CONFIG_SYS_MEM_MAP
+       - CONFIG_SYS_PTL1_ENTRIES - number of 1st level page table entries
+       - CONFIG_SYS_PTL2_ENTRIES - number of 1nd level page table entries
+         for the largest CONFIG_SYS_MEM_MAP entry
+       - CONFIG_COREID_MASK - the mask value used to get the core from the
+         MPIDR_EL1 register
+       - CONFIG_SYS_PTL2_BITS - number of bits addressed by the 2nd level
+         page tables
+       - CONFIG_SYS_BLOCK_SHIFT - number of bits addressed by a single block
+         entry from L2 page tables
+       - CONFIG_SYS_PGTABLE_SIZE - total size of the page table
+       - CONFIG_SYS_TCR_EL{1,2,3}_IPS_BITS - the IPS field of the TCR_EL{1,2,3}
+
+
+
+
 Contributor
 ===========
-   Tom Rini       <trini@ti.com>
-   Scott Wood     <scottwood@freescale.com>
-   York Sun       <yorksun@freescale.com>
-   Simon Glass    <sjg@chromium.org>
-   Sharma Bhupesh <bhupesh.sharma@freescale.com>
-   Rob Herring    <robherring2@gmail.com>
+   Tom Rini            <trini@ti.com>
+   Scott Wood          <scottwood@freescale.com>
+   York Sun            <yorksun@freescale.com>
+   Simon Glass         <sjg@chromium.org>
+   Sharma Bhupesh      <bhupesh.sharma@freescale.com>
+   Rob Herring         <robherring2@gmail.com>
+   Sergey Temerkhanov  <s.temerkhanov@gmail.com>