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https://github.com/AsahiLinux/u-boot
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Switch to an SPL image. The SPL for Ventana does the following: - setup i2c and read the factory programmed EEPROM to obtain DRAM config and model for board-specific calibration data - configure DRAM per CPU/size/layout/devices/calibration - load u-boot.img from NAND and jump to it This allows for a single SPL+u-boot.img to replace the previous multiple boa configurations. Cc: Stefan Roese <sr@denx.de> Cc: Otavio Salvador <otavio@ossystems.com.br> Cc: Andy Ng <andreas2025@gmail.com> Cc: Eric Nelson <eric.nelson@boundarydevices.com> Cc: Tapani Utriainen <tapani@technexion.com> Cc: Tom Rini <trini@ti.com> Signed-off-by: Tim Harvey <tharvey@gateworks.com>
83 lines
3.3 KiB
Text
83 lines
3.3 KiB
Text
U-Boot for the Gateworks Ventana Product Family boards
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This file contains information for the port of U-Boot to the Gateworks
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Ventana Product family boards.
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1. Secondary Program Loader (SPL)
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---------------------------------
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The i.MX6 has a BOOT ROM PPL (Primary Program Loader) which supports loading
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an executable image from various boot devices.
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The Gateworks Ventana board config uses an SPL build configuration. This
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will build the following artifacts from u-boot source:
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- SPL - Secondary Program Loader that the i.MX6 BOOT ROM (Primary Program
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Loader) boots. This detects CPU/DRAM configuration, configures
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The DRAM controller, loads u-boot.img from the detected boot device,
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and jumps to it. As this is booted from the PPL, it has an IVT/DCD
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table.
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- u-boot.img - The main u-boot core which is u-boot.bin with a image header.
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2. Build
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--------
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To build U-Boot for the Gateworks Ventana product family:
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make gwventana_config
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make
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3. Boot source, boot from NAND
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------------------------------
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The i.MX6 BOOT ROM expects some structures that provide details of NAND layout
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and bad block information (referred to as 'bootstreams') which are replicated
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multiple times in NAND. The number of replications and their spacing (referred
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to as search stride) is configurable through board strapping options and/or
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eFUSE settings (BOOT_SEARCH_COUNT / Pages in block from BOOT_CFG2). In
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addition, the i.MX6 BOOT ROM Flash Configuration Block (FCB) supports two
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copies of a bootloader in flash in the case that a bad block has corrupted one.
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The Freescale 'kobs-ng' application from the Freescale LTIB BSP, which runs
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under Linux and operates on an MTD partition, must be used to program the
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bootstream in order to setup this flash structure correctly.
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The Gateworks Ventana boards with NAND flash have been factory programmed
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such that their eFUSE settings expect 2 copies of the boostream (this is
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specified by providing kobs-ng with the --search_exponent=1 argument). Once in
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Linux with MTD support for the NAND on /dev/mtd0 you can program the SPL
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with:
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kobs-ng init -v -x --search_exponent=1 SPL
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The kobs-ng application uses an imximage which contains the Image Vector Table
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(IVT) and Device Configuration Data (DCD) structures that the i.MX6 BOOT ROM
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requires to boot. The kobs-ng adds the Firmware Configuration Block (FCB) and
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Discovered Bad Block Table (DBBT). The SPL build artifact from u-boot is
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an imximage.
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The u-boot.img, which is the non SPL u-boot binary appended to a u-boot image
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header must be programmed in the NAND flash boot device at an offset hard
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coded in the SPL. For the Ventana boards, this has been chosen to be 14MB.
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The image can be programmed from either u-boot or Linux:
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u-boot:
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Ventana > setenv mtdparts mtdparts=nand:14m(spl),2m(uboot),1m(env),-(rootfs)
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Ventana > tftp ${loadaddr} u-boot.img && nand erase.part uboot && \
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nand write ${loadaddr} uboot ${filesize}
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Linux:
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nandwrite /dev/mtd1 u-boot.img
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The above assumes the default Ventana partitioning scheme which is configured
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via the mtdparts env var:
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- spl: 14MB
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- uboot: 2M
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- env: 1M
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- rootfs: the rest
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This information is taken from:
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http://trac.gateworks.com/wiki/ventana/bootloader#NANDFLASH
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More details about the i.MX6 BOOT ROM can be found in the IMX6 reference manual.
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