forked from OERV-BSP/u-boot
95c1bb5f55
Provide the settings for using the debug UART in SPL. Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com> Reviewed-by: E Shattow <e@freeshell.de>
104 lines
3.1 KiB
ReStructuredText
104 lines
3.1 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0-or-later
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Boot source selection
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---------------------
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The board provides DIP switches to select the device for loading the boot
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firmware.
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=========== === ===
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Boot source SW1 SW2
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=========== === ===
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UART OFF OFF
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SD-card ON OFF
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eMMC OFF ON
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SPI flash ON ON
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=========== === ===
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Flashing a new U-Boot version
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-----------------------------
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U-Boot SPL is provided as file spl/u-boot-spl.bin.normal.out. Main U-Boot is
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in file u-boot.itb.
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Assuming your new U-Boot version is on partition 1 of an SD-card you could
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install it to the SPI flash with:
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.. code-block:: console
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sf probe
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load mmc 1:1 $kernel_addr_r u-boot-spl.bin.normal.out
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sf update $kernel_addr_r 0 $filesize
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load mmc 1:1 $kernel_addr_r u-boot.itb
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sf update $kernel_addr_r 0x100000 $filesize
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For loading the files from a TFTP server refer to the dhcp and tftpboot
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commands.
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After updating U-Boot you may want to erase a saved environment and reboot.
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.. code-block:: console
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env erase
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reset
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Booting from SD-Card
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--------------------
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The device boot ROM loads U-Boot SPL (u-boot-spl.bin.normal.out) from the
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partition with type GUID 2E54B353-1271-4842-806F-E436D6AF6985. You are free
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to choose any partition number.
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With the default configuration U-Boot SPL loads the U-Boot FIT image
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(u-boot.itb) from partition 2 (CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION=0x2).
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When formatting it is recommended to use GUID
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BC13C2FF-59E6-4262-A352-B275FD6F7172 for this partition.
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Booting from eMMC
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-----------------
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The device boot ROM tries to load U-Boot SPL (u-boot-spl.bin.normal.out) from
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sector 0 of the eMMC's main hardware partition. But this conflicts with GPT
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partitioning. Fortunately eMMC can alternatively load U-Boot SPL from a backup
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position.
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For U-Boot SPL (u-boot-spl.bin.normal.out) starting at sector 2048 (position
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0x100000) write the following bytes to the eMMC device after GPT partitioning:
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======= ========================
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Address Bytes
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======= ========================
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0x0000 40 02 00 00 00 00 10 00
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0x0290 40 02 00 00 00 00 10 00
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======= ========================
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With the default configuration U-Boot SPL loads the U-Boot FIT image
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(u-boot.itb) from partition 2 (CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION=0x2).
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When formatting it is recommended to use GUID
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BC13C2FF-59E6-4262-A352-B275FD6F7172 for this partition.
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Booting from UART
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-----------------
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The boot ROM supports the X-modem protocol to upload
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spl/u-boot-spl.bin.normal.out. U-Boot SPL support loading the FIT image
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u-boot.itb via the Y-modem protocol.
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Due to restrictions of the boot ROM not all X-modem implementations are
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compatible. The package tio (https://github.com/tio/tio) has been found to be
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usable.
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Debug UART
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----------
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By default the SBI interface is used for the debug UART. But this only works
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in main U-Boot. To enable the debug UART in SPL, too, use the following
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settings::
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CONFIG_DEBUG_UART=y
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CONFIG_DEBUG_UART_NS16550=y
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CONFIG_DEBUG_UART_BASE=0x10000000
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CONFIG_SPL_DEBUG_UART_BASE=0x10000000
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CONFIG_DEBUG_UART_CLOCK=24000000
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CONFIG_DEBUG_UART_SHIFT=2
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