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Update m68k documentation to reflect the current ColdFire architecture support status. Signed-off-by: Angelo Dureghello <angelo@sysam.it>
151 lines
4.8 KiB
Plaintext
151 lines
4.8 KiB
Plaintext
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U-Boot for Motorola (or Freescale/NXP) ColdFire processors
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===============================================================================
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History
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November 02, 2017 Angelo Dureghello <angelo@sysam.it>
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August 08, 2005 Jens Scharsig <esw@bus-elektronik.de>
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MCF5282 implementation without preloader
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January 12, 2004 <josef.baumgartner@telex.de>
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===============================================================================
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This file contains status information for the port of U-Boot to the
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Motorola ColdFire series of CPUs.
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1. Overview
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The ColdFire instruction set is "assembly source" compatible but an evolution
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of the original 68000 instruction set. Some not much used instructions has
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been removed. The instructions are only 16, 32, or 48 bits long, a
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simplification compared to the 68000 series.
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Bernhard Kuhn ported U-Boot 0.4.0 to the Motorola ColdFire architecture.
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The patches of Bernhard support the MCF5272 and MCF5282. A great disadvantage
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of these patches was that they needed a pre-bootloader to start U-Boot.
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Because of this, a new port was created which no longer needs a first stage
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booter.
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Thanks mainly to Freescale but also to several other contributors, U-Boot now
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supports nearly the entire range of ColdFire processors and their related
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development boards.
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2. Supported CPU families
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Please "make menuconfig" with ARCH=m68k, or check arch/m68k/cpu to see the
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currently supported processor and families.
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3. Supported boards
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U-Boot supports actually more than 40 ColdFire based boards.
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Board configuration can be done trough include/configs/<boardname>.h but the
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current recommended method is to use the new and more friendly approach as
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the "make menuconfig" way, very similar to the Linux way.
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To know details as memory map, build targets, default setup, etc, of a
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specific board please check:
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include/configs/<boardname>.h
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and/or
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configs/<boardname>_defconfig
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It is possible to build all ColdFire boards in a single command-line command,
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from u-boot root directory, as:
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./tools/buildman/buildman m68k
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3.1. Build U-Boot for a specific board
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A bash script similar to the one below may be used:
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#!/bin/bash
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export CROSS_COMPILE=/opt/toolchains/m68k/gcc-4.9.0-nolibc/bin/m68k-linux-
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board=M5475DFE
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make distclean
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make ARCH=m68k ${board}_defconfig
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make ARCH=m68k KBUILD_VERBOSE=1
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4. Adopted toolchains
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Please check:
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https://www.denx.de/wiki/U-Boot/ColdFireNotes
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5. ColdFire specific configuration options/settings
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5.1. Configuration to use a pre-loader
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If U-Boot should be loaded to RAM and started by a pre-loader
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CONFIG_MONITOR_IS_IN_RAM must be defined. If it is defined the
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initial vector table and basic processor initialization will not
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be compiled in. The start address of U-Boot must be adjusted in
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the boards config header file (CONFIG_SYS_MONITOR_BASE) and Makefile
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(CONFIG_SYS_TEXT_BASE) to the load address.
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5.2 ColdFire CPU specific options/settings
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To specify a CPU model, some defines shoudl be used, i.e.:
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CONFIG_MCF52x2 -- defined for all MCF52x2 CPUs
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CONFIG_M5272 -- defined for all Motorola MCF5272 CPUs
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Other options, generally set inside include/configs/<boardname>.h, they may
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apply to one or more cpu for the ColdFire family:
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CONFIG_SYS_MBAR -- defines the base address of the MCF5272 configuration
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registers
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CONFIG_SYS_ENET_BD_BASE
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-- defines the base address of the FEC buffer descriptors
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CONFIG_SYS_SCR -- defines the contents of the System Configuration Register
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CONFIG_SYS_SPR -- defines the contents of the System Protection Register
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CONFIG_SYS_MFD -- defines the PLL Multiplication Factor Divider
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(see table 9-4 of MCF user manual)
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CONFIG_SYS_RFD -- defines the PLL Reduce Frequency Devider
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(see table 9-4 of MCF user manual)
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CONFIG_SYS_CSx_BASE
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-- defines the base address of chip select x
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CONFIG_SYS_CSx_SIZE
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-- defines the memory size (address range) of chip select x
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CONFIG_SYS_CSx_WIDTH
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-- defines the bus with of chip select x
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CONFIG_SYS_CSx_MASK
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-- defines the mask for the related chip select x
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CONFIG_SYS_CSx_RO
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-- if set to 0 chip select x is read/write else chip select
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is read only
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CONFIG_SYS_CSx_WS
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-- defines the number of wait states of chip select x
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CONFIG_SYS_CACHE_ICACR
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CONFIG_SYS_CACHE_DCACR
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CONFIG_SYS_CACHE_ACRX
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-- cache-related registers config
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CONFIG_SYS_SDRAM_BASE
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CONFIG_SYS_SDRAM_SIZE
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CONFIG_SYS_SDRAM_BASEX
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CONFIG_SYS_SDRAM_CFG1
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CONFIG_SYS_SDRAM_CFG2
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CONFIG_SYS_SDRAM_CTRL
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CONFIG_SYS_SDRAM_MODE
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CONFIG_SYS_SDRAM_EMOD
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-- SDRAM config for SDRAM controller-specific registers, please
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see arch/m68k/cpu/<specific_cpu>/start.S files to see how
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these options are used.
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CONFIG_MCFUART
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-- defines enabling of ColdFire UART driver
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CONFIG_SYS_UART_PORT
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-- defines the UART port to be used (only a single UART can be
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actually enabled)
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CONFIG_SYS_SBFHDR_SIZE
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-- size of the prepended SBF header, if any
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