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https://github.com/AsahiLinux/u-boot
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1a4596601f
Signed-off-by: Wolfgang Denk <wd@denx.de> [trini: Fixup common/cmd_io.c] Signed-off-by: Tom Rini <trini@ti.com>
73 lines
1.9 KiB
Text
73 lines
1.9 KiB
Text
/*
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* (C) Copyright 2000
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* Dave Ellis, SIXNET, dge@sixnetio.com
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*
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* SPDX-License-Identifier: GPL-2.0+
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*/
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Using the Motorola MPC8XXFADS development board
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===============================================
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CONFIGURATIONS
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--------------
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There are ready-to-use default configurations available for the
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FADS823, FADS850SAR and FADS860T. The FADS860T configuration also
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works for the 855T processor.
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LOADING U-Boot INTO FADS FLASH MEMORY
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--------------------------------------
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MPC8BUG can load U-Boot into the FLASH memory using LOADF.
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loadf u-boot.srec 100000
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STARTING U-Boot FROM MPC8BUG
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-----------------------------
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To start U-Boot from MPC8BUG:
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1. Reset the board:
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reset :h
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2. Change BR0 and OR0 back to their values at reset:
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rms memc br0 00000001
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rms memc or0 00000d34
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3. Modify DER so MPC8BUG gets control only when it should:
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rms der 2002000f
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4. Start as if from reset:
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go 100
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This is NOT exactly the same as starting U-Boot without
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MPC8BUG. MPC8BUG turns off the watchdog as part of the hard reset.
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After it does the reset it writes SYPCR (to disable the watchdog)
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and sets BR0 and OR0 to map the FLASH at 0x02800000 (and does lots
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of other initialization). That is why it is necessary to set BR0
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and OR0 to map the FLASH everywhere. U-Boot can't turn on the
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watchdog after that, since MPC8BUG has used the only chance to write
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to SYPCR.
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Here is a bizarre sequence of MPC8BUG and U-Boot commands that lets
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U-Boot write to SYPCR. It works with MPC8BUG 1.5 and an 855T
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processor (your mileage may vary). It is probably better (and a lot
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easier) just to accept having the watchdog disabled when the debug
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cable is connected.
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in MPC8BUG:
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reset :h
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rms memc br0 00000001
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rms memc or0 00000d34
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rms der 2000f
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go 100
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Now U-Boot is running with the MPC8BUG value for SYPCR. Use the
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U-Boot 'reset' command to reset the board.
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=>reset
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Next, in MPC8BUG:
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rms der 2000f
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go
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Now U-Boot is running with the U-Boot value for SYPCR.
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