u-boot/board/liebherr/xea
Masahiro Yamada b75d8dc564 treewide: convert bd_t to struct bd_info by coccinelle
The Linux coding style guide (Documentation/process/coding-style.rst)
clearly says:

  It's a **mistake** to use typedef for structures and pointers.

Besides, using typedef for structures is annoying when you try to make
headers self-contained.

Let's say you have the following function declaration in a header:

  void foo(bd_t *bd);

This is not self-contained since bd_t is not defined.

To tell the compiler what 'bd_t' is, you need to include <asm/u-boot.h>

  #include <asm/u-boot.h>
  void foo(bd_t *bd);

Then, the include direcective pulls in more bloat needlessly.

If you use 'struct bd_info' instead, it is enough to put a forward
declaration as follows:

  struct bd_info;
  void foo(struct bd_info *bd);

Right, typedef'ing bd_t is a mistake.

I used coccinelle to generate this commit.

The semantic patch that makes this change is as follows:

  <smpl>
  @@
  typedef bd_t;
  @@
  -bd_t
  +struct bd_info
  </smpl>

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-07-17 09:30:13 -04:00
..
Kconfig imx: Add support for i.MX28 based XEA board 2020-01-07 10:26:56 +01:00
MAINTAINERS imx: Add support for i.MX28 based XEA board 2020-01-07 10:26:56 +01:00
Makefile imx: Add support for i.MX28 based XEA board 2020-01-07 10:26:56 +01:00
README imx: Add support for i.MX28 based XEA board 2020-01-07 10:26:56 +01:00
spl_xea.c imx: Add support for i.MX28 based XEA board 2020-01-07 10:26:56 +01:00
xea.c treewide: convert bd_t to struct bd_info by coccinelle 2020-07-17 09:30:13 -04:00

Building SPL/U-Boot for xea board
=================================

Setup environment, configure and build, e.g. by:

 $ make imx28_xea_defconfig
 $ make -j4 u-boot.sb u-boot.img

Now you should see u-boot.sb and u-boot.img files in the build directory.


Booting
=======

The boot ROM loads SPL from SPI NOR flash into SRAM.  SPL configures
DRAM and loads either a Linux kernel (falcon mode) or, if the rescue
pin is asserted, the main U-Boot.  Both kernel and U-Boot reside in
eMMC boot partition 0.  For redundancy, a copy of U-Boot is also
stored in SPI flash.  If a valid kernel image is not found, U-Boot is
loaded from eMMC or, if this fails, SPI flash.

Boot area layout
----------------

SPI NOR
Offset          Function        File
------------------------------------------
0x00000000      SPL             u-boot.sb
0x00010000      U-Boot          u-boot.img
0x00080000      Environment

eMMC
Offset          Function        File
------------------------------------------
0x00000000      U-Boot          u-boot.img
0x00080000      Devicetree      imx28-bttc.dtb
0x00100000      Kernel          uImage


Falcon mode
===========

In falcon mode, the default, SPL loads the kernel and devicetree
directly.  For this to work, the stored devicetree must include
correct "memory" and "chosen" nodes as these are not updated by SPL
before booting the kernel.


Updating from U-Boot
====================

The default U-Boot environment includes command sequences to update
SPL, U-Boot, and kernel over TFTP.  These are as follows:

- update_spl: writes u-boot.sb to SPI NOR
- update_uboot: writes u-boot.img to eMMC and SPI NOR
- update_kernel: writes kernel and devicetree to eMMC

They can be invoked at the U-Boot prompt using the "run" command,
e.g. "run update_spl" to update the SPL.

These update commands download the above-named files from the
${hostname} directory on the server provided by DHCP.