[v3] zynq: document how to use custom ps7_init files

From: Masahiro Yamada <yamada.masahiro@socionext.com>

Since U-Boot supported SPL for Zynq boards at v2014.04 release, it
became much easier to build a system.  At that time, however, users
still needed to manually copy ps7_init.c/h to the U-Boot source tree
to generate a working SPL image because ps7_init.c/h output from
Xilinx tools are not compatible with GPL.

Later, the license problem was solved when Xilinx tools became able
to output the GPL-compatible variants (ps7_init_gpl.c/h) as well.
U-Boot v2015.07 or later includes ps7_init_gpl.c/h for major Zynq
boards so that users can build a boot image straight away.

Now Buildroot supports 3 boards (Zedboard, MicroZed, ZC706) without
any manual intervention.  This is a good thing itself, but commit
b9cd72cdbfe3 ("zynq_zc706: bump U-Boot to xilinx-v2016.2") entirely
dropped the information about custom ps7_init files.

This commit provides up-to-date guidance for how to customize the
ps7_init files.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Matt Weber <matthew.weber@rockwellcollins.com>

---
v2 -> v3
[Arnout
 - Moved notice of good build but bad images to top
 - Updated wording when refering to files
 - Removed redundant comment on overriding files
 - Added suggested note on file copy and make clean's affect

v1 -> v2
 - Updated readme wording discussed in
   https://patchwork.ozlabs.org/patch/654309/

---
 board/zynq/readme.txt | 46 +++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 39 insertions(+), 7 deletions(-)

On Mon, Oct 3, 2016 at 6:09 PM, Matt Weber
<matthew.weber@rockwellcollins.com> wrote:
> From: Masahiro Yamada <yamada.masahiro@socionext.com>
>
> Since U-Boot supported SPL for Zynq boards at v2014.04 release, it
> became much easier to build a system.  At that time, however, users
> still needed to manually copy ps7_init.c/h to the U-Boot source tree
> to generate a working SPL image because ps7_init.c/h output from
> Xilinx tools are not compatible with GPL.
>
> Later, the license problem was solved when Xilinx tools became able
> to output the GPL-compatible variants (ps7_init_gpl.c/h) as well.
> U-Boot v2015.07 or later includes ps7_init_gpl.c/h for major Zynq
> boards so that users can build a boot image straight away.
>
> Now Buildroot supports 3 boards (Zedboard, MicroZed, ZC706) without
> any manual intervention.  This is a good thing itself, but commit
> b9cd72cdbfe3 ("zynq_zc706: bump U-Boot to xilinx-v2016.2") entirely
> dropped the information about custom ps7_init files.
>
> This commit provides up-to-date guidance for how to customize the
> ps7_init files.
>
> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
> Signed-off-by: Matt Weber <matthew.weber@rockwellcollins.com>

This looks good to me. If you want me to look at future Xilinx related
patches just CC me and I'll comment/help where I can.

Acked-by: Alistair Francis <alistair.francis@xilinx.com>

Thanks,

Alistair

>
> ---
> v2 -> v3
> [Arnout
>  - Moved notice of good build but bad images to top
>  - Updated wording when refering to files
>  - Removed redundant comment on overriding files
>  - Added suggested note on file copy and make clean's affect
>
> v1 -> v2
>  - Updated readme wording discussed in
>    https://patchwork.ozlabs.org/patch/654309/
>
> ---
>  board/zynq/readme.txt | 46 +++++++++++++++++++++++++++++++++++++++-------
>  1 file changed, 39 insertions(+), 7 deletions(-)
>
> diff --git a/board/zynq/readme.txt b/board/zynq/readme.txt
> index 51e28b6..24c12dd 100644
> --- a/board/zynq/readme.txt
> +++ b/board/zynq/readme.txt
> @@ -6,13 +6,6 @@ Currently, three boards are natively supported by Buildroot:
>   - Avnet ZedBoard (zynq_zed_defconfig)
>   - Avnet MicroZed (zynq_microzed_defconfig)
>
> -The following build procedure focuses on them, but you can adjust it to your
> -board even if it is not listed above.  Major Zynq-based boards are supported by
> -U-Boot, and their Device Trees are merged in Linux Kernel.  If your board is the
> -case, booting the kernel is a piece of cake.  All you need to do is to change:
> - - Kernel Device Tree file name (BR2_LINUX_KERNEL_INTREE_DTS_NAME)
> - - U-Boot board defconfig (BR2_TARGET_UBOOT_BOARD_KCONFIG)
> -
>  Steps to create a working system for a Zynq board:
>
>  1) Configuration (do one of the following)
> @@ -50,3 +43,42 @@ References:
>
>   - Zedboard/Microzed information including schematics, reference designs, and
>     manuals are available from http://www.zedboard.org .
> +
> +Support for other boards:
> +
> +If you want to build a system for other boards (for ex. Digilent Zybo board).
> +Most major Zynq-based boards have U-Boot and Kernel support.  If your
> +board happens to be supported, booting the kernel and using U-Boot
> +just requires the following Buildroot updates:
> + - Kernel Device Tree file name (BR2_LINUX_KERNEL_INTREE_DTS_NAME)
> + - U-Boot board defconfig (BR2_TARGET_UBOOT_BOARD_DEFCONFIG)
> +
> +Custom ps7_init_gpl.c/h support:
> +
> +To generate a working boot.bin image, ps7_init_gpl.c/h are required in the
> +U-Boot source tree.  Without those files, boot.bin will be built successfully
> +but it will not be functional at all.  Those files are output from the Xilinx
> +tools, but for convenience, U-Boot includes the default ps7_init_gpl.c/h of
> +popular boards.  Those files may need to be updated for any programmable
> +logic customizations which impact ps7_init (clock/pin setup & mapping/AXI
> +bridge setup/etc).  See board/xilinx/zynq/ directory of U-Boot for natively
> +supported ps7_init files.  If the ps7_init files for your board are not found
> +in U-Boot, you need to add them by yourself.
> +
> +1) Start with a defconfig supported by Buildroot (e.g. Zedboard)
> +    make zynq_zed_defconfig
> +
> +2) make uboot-menuconfig
> +    Visit the following menu and enable CONFIG_ZYNQ_CUSTOM_INIT.
> +
> +    ARM architecture  --->
> +       [*] Use custom ps7_init provided by Xilinx tool
> +
> +3) Copy ps7_init_gpl.c/h generated by the Xilinx tools into
> +   output/build/uboot-xilinx-<pkg version>/board/xilinx/zynq/custom_hw_platform/
> +
> +4) make
> +
> +Note: The files in step 3 will need to be re-copied after cleaning the output
> +directory and at this time, there is no way to save them as part of the buildroot
> +configuration, except as a U-Boot patch.
> --
> 1.9.1
>
> _______________________________________________
> buildroot mailing list
> buildroot@busybox.net
> http://lists.busybox.net/mailman/listinfo/buildroot

Hello,

On Mon,  3 Oct 2016 20:09:56 -0500, Matt Weber wrote:
> From: Masahiro Yamada <yamada.masahiro@socionext.com>
> 
> Since U-Boot supported SPL for Zynq boards at v2014.04 release, it
> became much easier to build a system.  At that time, however, users
> still needed to manually copy ps7_init.c/h to the U-Boot source tree
> to generate a working SPL image because ps7_init.c/h output from
> Xilinx tools are not compatible with GPL.
> 
> Later, the license problem was solved when Xilinx tools became able
> to output the GPL-compatible variants (ps7_init_gpl.c/h) as well.
> U-Boot v2015.07 or later includes ps7_init_gpl.c/h for major Zynq
> boards so that users can build a boot image straight away.
> 
> Now Buildroot supports 3 boards (Zedboard, MicroZed, ZC706) without
> any manual intervention.  This is a good thing itself, but commit
> b9cd72cdbfe3 ("zynq_zc706: bump U-Boot to xilinx-v2016.2") entirely
> dropped the information about custom ps7_init files.
> 
> This commit provides up-to-date guidance for how to customize the
> ps7_init files.
> 
> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
> Signed-off-by: Matt Weber <matthew.weber@rockwellcollins.com>
> 
> ---
> v2 -> v3
> [Arnout
>  - Moved notice of good build but bad images to top
>  - Updated wording when refering to files
>  - Removed redundant comment on overriding files
>  - Added suggested note on file copy and make clean's affect

I've applied, after reworking a bit some aspects, and tweaking the
formatting.

Thanks!

Thomas