Added couple links

# Ezynq 

Ezynq project is started to create a bootloader for systems based on the Xilinx Zynq SoC without

the inconvenience of the non-free tools and/or files.

The goal is not just to "free" the code, but to provide users with the higher degree of flexibi-

include/autoconf.mk (it is generated by "make include/autoconf.mk") and generates several output

files:

1 - the header file (default name boot_head.bin) formatted for the Zynq ROM Boot Loader (RBL)

1. the header file (default name boot_head.bin) formatted for the Zynq ROM Boot Loader (RBL)

according to section 6.3.2 of Xilinx UG585 -"Zynq-7000 AP SoC Technical Reference Manual". This

file uses RBL register initialization feature to set registers (MIO, DDR) that can be written

before system clocks and DDR memory are initialized - that requires polling status information

and waiting for particular states are reached.

2 - ezynq.c file to be compiled and linked with other U-boot files. All ezynq-specific code is

2. *ezynq.c* file to be compiled and linked with other U-boot files. All ezynq-specific code is

called by a modified version of the arch_cpu_init() function - the only difference from the

U-boot version for Xilinx Zynq designed to be used with the proprietary FSBL program. This code

finishes register initialization (contrary to RBL it can wait for certain states are reached)

U-boot takes over from there. Optionally the debug code is generated that controls the LED state

at different stages of the boot process and outputs register states to the serial port.

3 - html output file (default name u-boot.html) that lists the configuration parameters used

3. html output file (default name u-boot.html) that lists the configuration parameters used

(specified and calculated from others), used PLLs and clocks, configured interfaces and their

usage of the MIO pins. It then lists all the registers written by RBL and written/tested during

execution of the arch_cpu_init(). Most of the registers are listed in the same sequence as they

the OCM) so U-boot can be loaded in a simple one-stage process without the need of the SPL when

first a mini-version of U-boot is loaded, and that version later loads the full U-boot to DRAM.

Generated arch_cpu_init() starts running in OCM, initializes DRAM, copies itself (first 192K

Generated *arch_cpu_init()* starts running in OCM, initializes DRAM, copies itself (first 192K

OCM) to DRAM to 0x4000000.0x402ffff (using just C, not assembly code) and than adds 0x4000000 to

the program counter. In this state it is possible to map DRAM to the 0x0.0x2ffff instead of the

OCM and copy 0x4000000.0x402ffff back to 0x0.0x2ffff and so return from the function

the source and destination addresses are the same) and the data memory is initialized when 192K

OCM limit is not in effect anymore. 

INSTALLATION (see below for testing without U-boot installation)

## INSTALLATION (see below for testing without U-boot installation)

When Ezynq repository is cloned, there is install_uboot.sh script in the top directory. Running

this script clones u-boot-xlnx and then adds links to the files in Ezynq sub-directory

These links created by install_uboot.sh add new configuration files and replace 3 files in the

  u-boot-xlnx:

* boards.cfg - adding zynq-microzed there

* arch/arm/cpu/armv7/zynq/cpu.c - disabling arch_cpu_init() there if configuration was made for

  Ezynq

  arch/arm/cpu/armv7/zynq/ezynq.c

New files include:

* include/configs/zynq_microzed.h configuration parameters for U-boot features, described in

* *include/configs/zynq_microzed.h* configuration parameters for U-boot features, described in

  U-boot README file

* include/configs/ezynq/ezynq_MT41K256M16RE125.h - Ezynq configuration parameters containing

* *include/configs/ezynq/ezynq_MT41K256M16RE125.h* - Ezynq configuration parameters containing

  Micron DDR3 memory datasheet for the memory used by MicroZed board

* include/configs/ezynq/ezynq_XC7Z010_1CLG400.h - Ezynq configuration parameters containing

* *include/configs/ezynq/ezynq_XC7Z010_1CLG400.h* - Ezynq configuration parameters containing

  Xilinx Zynq datasheet data for the SoC used by MicroZed board

* include/configs/ezynq/ezynq_XC7Z010_1CLG400.h - Ezynq configuration parameters containing

* *include/configs/ezynq/ezynq_XC7Z010_1CLG400.h* - Ezynq configuration parameters containing

  Xilinx Zynq datasheet data for the SoC used by MicroZed board

* include/configs/ezynq/zed_ezynq.h - rest of the Ezynq configuration parameters (it has the

  include lines for the 2 datasheet files listed above)

* makeuboot - script that configures U-boot for the microzed board, creates include/autoconf.mk,

* *makeuboot* - script that configures U-boot for the microzed board, creates include/autoconf.mk,

  runs ezynqcfg.py to create Ezynq code (RBL header and ezynq.c), builds and links U-boot

  generating u-boot.bin, reruns ezynqcfg.py to include the length of the u-boot.bin into

  boot_head.bin and then combines boot_head.bin and u-boot.bin into boot.bin with a simple

  'cat' command.

 TESTING WITHOUT U-BOOT AND CROSS-COMPILER TOOLCHAIN

## Testing without u-boot and cross-compiler toolchain

 It is possible to try just the ezynqcfg.py script without building u-boot, no ARM toolchain

 is required  

 This command uses a demo test.mk that mimics include/autoconf.mk and generates test.html and

 ezynq.c files  

KNOWN ISSUES

## Useful links

* [Ezynq wiki page](http://wiki.elphel.com/index.php?title=Ezynq)

* [meta-ezynq](https://sourceforge.net/p/elphel/meta-ezynq) - recipes for Yocto Poky

## Known issues

1. USB does not work yet.

2. Ethernet is not tested (on the board we have it does not work with provided images, so we

   suspect a hardware problem.

3. Bitstream loading is not tested, current code does not enable level shifters - it may be

   more appropriate to do just before loading of the bitstream.

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