Overview:
=========

The MPC8536E integrates a PowerPC processor core with system logic
required for imaging, networking, and communications applications.

Boot from NAND:
===============

The MPC8536E is capable of booting from NAND flash which uses the image
u-boot-nand.bin. This image contains two parts: a first stage image(also
call 4K NAND loader and a second stage image. The former is appended to
the latter to produce u-boot-nand.bin.

The bootup process can be divided into two stages: the first stage will
configure the L2SRAM, then copy the second stage image to L2SRAM and jump
to it. The second stage image is to configure all the hardware and boot up
to U-Boot command line.

The 4K NAND loader's code comes from the corresponding nand_spl directory,
along with the code twisted by CONFIG_NAND_SPL. The macro CONFIG_NAND_SPL
is mainly used to shrink the code size to the 4K size limitation.

The macro CONFIG_SYS_RAMBOOT is used to control the code to produce the
second stage image. It's set in the board config file when boot from NAND
is selected.

Build and boot steps
--------------------

1. Building image
make MPC8536DS_NAND_config
make CROSS_COMPILE=powerpc-none-linux-gnuspe- all

2. Change dip-switch
SW2[5-8] = 1011
SW9[1-3] = 101
Note: 1 stands for 'on', 0 stands for 'off'

3. Flash image
tftp 1000000 u-boot-nand.bin
nand erase 0 a0000
nand write 1000000 0 a0000

Boot from On-chip ROM:
======================

The MPC8536E is capable of booting from the on-chip ROM - boot from eSDHC
and boot from eSPI. When power on, the porcessor excutes the ROM code to
initialize the eSPI/eSDHC controller, and loads the mian U-Boot image from
the memory device that interfaced to the controller, such as the SDCard or
SPI EEPROM, to the target memory, e.g. SDRAM or L2SRAM, then boot from it.

The memory device should contain a specific data structure with control word
and config word at the fixed address. The config word direct the process how
to config the memory device, and the control word direct the processor where
to find the image on the memory device, or where copy the main image to. The
user can use any method to store the data structure to the memory device, only
if store it on the assigned address.

Build and boot steps
--------------------

For boot from eSDHC:
1. Build image
make MPC8536DS_SDCARD_config
make CROSS_COMPILE=powerpc-none-linux-gnuspe- all

2. Change dip-switch
SW2[5-8] = 0111
SW3[1] = 0
SW8[7] = 0 - The on-board SD/MMC slot is active
SW8[7] = 1 - The externel SD/MMC slot is active

3. Put image to SDCard
Put the follwing info at the assigned address on the SDCard:

Offset | Data | Description
--------------------------------------------------------
| 0x40-0x43 | 0x424F4F54 | BOOT signature |
--------------------------------------------------------
| 0x48-0x4B | 0x00080000 | u-boot.bin's size |
--------------------------------------------------------
| 0x50-0x53 | 0x???????? | u-boot.bin's Addr on SDCard |
--------------------------------------------------------
| 0x58-0x5B | 0xF8F80000 | Target Address |
-------------------------------------------------------
| 0x60-0x63 | 0xF8FFF000 | Execution Starting Address |
--------------------------------------------------------
| 0x68-0x6B | 0x6 | Number of Config Addr/Data |
--------------------------------------------------------
| 0x80-0x83 | 0xFF720100 | Config Addr 1 |
| 0x84-0x87 | 0xF8F80000 | Config Data 1 |
--------------------------------------------------------
| 0x88-0x8b | 0xFF720e44 | Config Addr 2 |
| 0x8c-0x8f | 0x0000000C | Config Data 2 |
--------------------------------------------------------
| 0x90-0x93 | 0xFF720000 | Config Addr 3 |
| 0x94-0x97 | 0x80010000 | Config Data 3 |
--------------------------------------------------------
| 0x98-0x9b | 0xFF72e40c | Config Addr 4 |
| 0x9c-0x9f | 0x00000040 | Config Data 4 |
--------------------------------------------------------
| 0xa0-0xa3 | 0x40000001 | Config Addr 5 |
| 0xa4-0xa7 | 0x00000100 | Config Data 5 |
--------------------------------------------------------
| 0xa8-0xab | 0x80000001 | Config Addr 6 |
| 0xac-0xaf | 0x80000001 | Config Data 6 |
--------------------------------------------------------
| ...... |
--------------------------------------------------------
| 0x???????? | u-boot.bin |
--------------------------------------------------------

then insert the SDCard to the active slot to boot up.

For boot from eSPI:
1. Build image
make MPC8536DS_SPIFLASH_config
make CROSS_COMPILE=powerpc-none-linux-gnuspe- all

2. Change dip-switch
SW2[5-8] = 0110

3. Put image to SPI flash
Put the info in the above table onto the SPI flash, then
boot up.