When Kconfig for U-boot was examined, one of the biggest issues was
how to support multiple images (Normal, SPL, TPL). There were
actually two options, "single .config" and "multiple .config".
After some discussions and thought experiments, I chose the latter,
i.e. to create ".config", "spl/.config", "tpl/.config" for Normal,
SPL, TPL, respectively.
It is true that the "multiple .config" strategy provided us the
maximum flexibility and helped to avoid duplicating CONFIGs among
Normal, SPL, TPL, but I have noticed some fatal problems:
[1] It is impossible to share CONFIG options across the images.
If you change the configuration of Main image, you often have to
adjust some SPL configurations correspondingly. Currently, we
cannot handle the dependencies between them. It means one of the
biggest advantages of Kconfig is lost.
[2] It is too painful to change both ".config" and "spl/.config".
Sunxi guys started to work around this problem by creating a new
configuration target. Commit cbdd9a9737 (sunxi: kconfig: Add
%_felconfig rule to enable FEL build of sunxi platforms.) added
"make *_felconfig" to enable CONFIG_SPL_FEL on both images.
Changing the configuration of multiple images in one command is a
generic demand. The current implementation cannot propose any
good solution about this.
[3] Kconfig files are getting ugly and difficult to understand.
Commit b724bd7d63 (dm: Kconfig: Move CONFIG_SYS_MALLOC_F_LEN to
Kconfig) has sprinkled "if !SPL_BUILD" over the Kconfig files.
[4] The build system got more complicated than it should be.
To adjust Linux-originated Kconfig to U-Boot, the helper script
"scripts/multiconfig.sh" was introduced. Writing a complicated
text processor is a shell script sometimes caused problems.
Now I believe the "single .config" will serve us better. With it,
all the problems above would go away. Instead, we will have to add
some CONFIG_SPL_* (and CONFIG_TPL_*) options such as CONFIG_SPL_DM,
but we will not have much. Anyway, this is what we do now in
scripts/Makefile.spl.
I admit my mistake with my apology and this commit switches to the
single .config configuration.
It is not so difficult to do that:
- Remove unnecessary processings from scripts/multiconfig.sh
This file will remain for a while to support the current defconfig
format. It will be removed after more cleanups are done.
- Adjust some makefiles and Kconfigs
- Add some entries to include/config_uncmd_spl.h and the new file
scripts/Makefile.uncmd_spl. Some CONFIG options that are not
supported on SPL must be disabled because one .config is shared
between SPL and U-Boot proper going forward. I know this is not
a beautiful solution and I think we can do better, but let's see
how much we will have to describe them.
- update doc/README.kconfig
More cleaning up patches will follow this.
Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
#
# Xilinx ZYNQ U-Boot
#
# (C) Copyright 2013 Xilinx, Inc.
#
# SPDX-License-Identifier: GPL-2.0+
#
1. About this
This document describes the information about Xilinx Zynq U-Boot -
like supported boards, ML status and TODO list.
2. Zynq boards
Xilinx Zynq-7000 All Programmable SoCs enable extensive system level
differentiation, integration, and flexibility through hardware, software,
and I/O programmability.
* zc70x
- zc702 (single qspi, gem0, mmc) [1]
- zc706 (dual parallel qspi, gem0, mmc) [2]
* zed (single qspi, gem0, mmc) [3]
* microzed (single qspi, gem0, mmc) [4]
* zc770
- zc770-xm010 (single qspi, gem0, mmc)
- zc770-xm011 (8 or 16 bit nand)
- zc770-xm012 (nor)
- zc770-xm013 (dual parallel qspi, gem1)
3. Building
# Configure for zc70x board
$ make zynq_zc70x_config
Configuring for zynq_zc70x board...
# Building default dts for zc702 board
$ make
# Building specified dts for zc706 board
$ make DEVICE_TREE=zynq-zc706
4. Bootmode
Zynq has a facility to read the bootmode from the slcr bootmode register
once user is setting through jumpers on the board - see page no:1546 on [5]
All possible bootmode values are defined in Table 6-2:Boot_Mode MIO Pins
on [5].
board_late_init() will read the bootmode values using slcr bootmode register
at runtime and assign the modeboot variable to specific bootmode string which
is intern used in autoboot.
SLCR bootmode register Bit[3:0] values
#define ZYNQ_BM_NOR 0x02
#define ZYNQ_BM_SD 0x05
#define ZYNQ_BM_JTAG 0x0
"modeboot" variable can assign any of "norboot", "sdboot" or "jtagboot"
bootmode strings at runtime.
5. Mainline status
- Added basic board configurations support.
- Added zynq u-boot bsp code - arch/arm/cpu/armv7/zynq
- Added zynq boards named - zc70x, zed, microzed, zc770_xm010, zc770_xm012, zc770_xm013
- Added zynq drivers:
serial - drivers/serial/serial_zynq.c
net - drivers/net/zynq_gem.c
mmc - drivers/mmc/zynq_sdhci.c
mmc - drivers/mmc/zynq_sdhci.c
spi- drivers/spi/zynq_spi.c
i2c - drivers/i2c/zynq_i2c.c
- Done proper cleanups on board configurations
- Added basic FDT support for zynq boards
- d-cache support for zynq_gem.c
6. TODO
- Add zynq boards support - zc770_xm011
- Add zynq qspi controller driver
- Add zynq nand controller driver
- Add FDT support on individual drivers
[1] http://www.xilinx.com/products/boards-and-kits/EK-Z7-ZC702-G.htm
[2] http://www.xilinx.com/products/boards-and-kits/EK-Z7-ZC706-G.htm
[3] http://zedboard.org/product/zedboard
[4] http://zedboard.org/product/microzed
[5] http://www.xilinx.com/support/documentation/user_guides/ug585-Zynq-7000-TRM.pdf
--
Jagannadha Sutradharudu Teki <jaganna@xilinx.com>
Sun Dec 15 14:52:41 IST 2013
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