Table of interleaving modes supported in cpu/8xxx/ddr/
======================================================
  +-------------+---------------------------------------------------------+
  |             |                   Rank Interleaving                     |
  |             +--------+-----------+-----------+------------+-----------+
  |Memory       |        |           |           |    2x2     |    4x1    |
  |Controller   |  None  | 2x1 lower | 2x1 upper | {CS0+CS1}, | {CS0+CS1+ |
  |Interleaving |        | {CS0+CS1} | {CS2+CS3} | {CS2+CS3}  |  CS2+CS3} |
  +-------------+--------+-----------+-----------+------------+-----------+
  |None         |  Yes   | Yes       | Yes       | Yes        | Yes       |
  +-------------+--------+-----------+-----------+------------+-----------+
  |Cacheline    |  Yes   | Yes       | No        | No, Only(*)| Yes       |
  |             |CS0 Only|           |           | {CS0+CS1}  |           |
  +-------------+--------+-----------+-----------+------------+-----------+
  |Page         |  Yes   | Yes       | No        | No, Only(*)| Yes       |
  |             |CS0 Only|           |           | {CS0+CS1}  |           |
  +-------------+--------+-----------+-----------+------------+-----------+
  |Bank         |  Yes   | Yes       | No        | No, Only(*)| Yes       |
  |             |CS0 Only|           |           | {CS0+CS1}  |           |
  +-------------+--------+-----------+-----------+------------+-----------+
  |Superbank    |  No    | Yes       | No        | No, Only(*)| Yes       |
  |             |        |           |           | {CS0+CS1}  |           |
  +-------------+--------+-----------+-----------+------------+-----------+
 (*) Although the hardware can be configured with memory controller
 interleaving using "2x2" rank interleaving, it only interleaves {CS0+CS1}
 from each controller. {CS2+CS3} on each controller are only rank
 interleaved on that controller.

 For memory controller interleaving, identical DIMMs are suggested. Software
 doesn't check the size or organization of interleaved DIMMs.

The ways to configure the ddr interleaving mode
==============================================
1. In board header file(e.g.MPC8572DS.h), add default interleaving setting
   under "CONFIG_EXTRA_ENV_SETTINGS", like:
	#define CONFIG_EXTRA_ENV_SETTINGS				\
	 "hwconfig=fsl_ddr:ctlr_intlv=bank"			\
	 ......

2. Run u-boot "setenv" command to configure the memory interleaving mode.
   Either numerical or string value is accepted.

  # disable memory controller interleaving
  setenv hwconfig "fsl_ddr:ctlr_intlv=null"

  # cacheline interleaving
  setenv hwconfig "fsl_ddr:ctlr_intlv=cacheline"

  # page interleaving
  setenv hwconfig "fsl_ddr:ctlr_intlv=page"

  # bank interleaving
  setenv hwconfig "fsl_ddr:ctlr_intlv=bank"

  # superbank
  setenv hwconfig "fsl_ddr:ctlr_intlv=superbank"

  # disable bank (chip-select) interleaving
  setenv hwconfig "fsl_ddr:bank_intlv=null"

  # bank(chip-select) interleaving cs0+cs1
  setenv hwconfig "fsl_ddr:bank_intlv=cs0_cs1"

  # bank(chip-select) interleaving cs2+cs3
  setenv hwconfig "fsl_ddr:bank_intlv=cs2_cs3"

  # bank(chip-select) interleaving (cs0+cs1) and (cs2+cs3)  (2x2)
  setenv hwconfig "fsl_ddr:bank_intlv=cs0_cs1_and_cs2_cs3"

  # bank(chip-select) interleaving (cs0+cs1+cs2+cs3) (4x1)
  setenv hwconfig "fsl_ddr:bank_intlv=cs0_cs1_cs2_cs3"

Memory controller address hashing
==================================
If the DDR controller supports address hashing, it can be enabled by hwconfig.

Syntax is:
hwconfig=fsl_ddr:addr_hash=true

Combination of hwconfig
=======================
Hwconfig can be combined with multiple parameters, for example, on a supported
platform

hwconfig=fsl_ddr:addr_hash=true,ctlr_intlv=cacheline,bank_intlv=cs0_cs1_cs2_cs3