[PATCH v6 5/8] m68k: Add support for M68040 CPU
Angelo Dureghello
angelo at kernel-space.org
Sat Jan 24 09:29:04 CET 2026
Hi Kuan-Wei,
i rebuilt all ColdFire boards and this patch is not causing any build
issue, and with some quick tests on stmark2 board there are no issues
either, nothing is broken.
Thanks a lot.
Acked-by: Angelo Dureghello <angelo at kernel-space.org>
On 1/7/26 21:18, Kuan-Wei Chiu wrote:
> Add support for the Motorola 68040 architecture. Currently, m68k
> support in U-Boot is primarily focused on ColdFire variants. Introduce
> the necessary infrastructure to support the classic M680x0 series,
> specifically targeting the M68040 as emulated by QEMU.
>
> The implementation includes exception vectors, early startup code, and
> minimal CPU initialization and relocation stubs. It also defines the
> standard m68k boot information structure used for passing hardware
> information to the operating system. To ensure compatibility, ColdFire-
> specific library objects such as cache and interrupt handling are
> excluded from the build when M68040 is selected.
>
> Additionally, apply a specific workaround during the early memory
> reservation stage. Use a manual loop to clear global data instead of
> the standard memset() function, as utilizing memset() at this point was
> observed to cause a hang on the QEMU platform.
>
> Signed-off-by: Kuan-Wei Chiu <visitorckw at gmail.com>
> ---
> Changes in v6:
> - Introduce hidden Kconfig symbol CONFIG_ARCH_COLDFIRE to group
> ColdFire-specific files in Makefile, removing the need for
> 'ifndef CONFIG_M680x0'.
> - Add help text for CONFIG_M680x0.
>
> MAINTAINERS | 6 +++
> arch/m68k/Kconfig | 30 +++++++++++++
> arch/m68k/Makefile | 1 +
> arch/m68k/config.mk | 10 ++++-
> arch/m68k/cpu/m680x0/Makefile | 6 +++
> arch/m68k/cpu/m680x0/cpu.c | 73 ++++++++++++++++++++++++++++++++
> arch/m68k/cpu/m680x0/start.S | 73 ++++++++++++++++++++++++++++++++
> arch/m68k/cpu/m680x0/u-boot.lds | 47 ++++++++++++++++++++
> arch/m68k/include/asm/bootinfo.h | 39 +++++++++++++++++
> arch/m68k/lib/Makefile | 7 +--
> 10 files changed, 284 insertions(+), 8 deletions(-)
> create mode 100644 arch/m68k/cpu/m680x0/Makefile
> create mode 100644 arch/m68k/cpu/m680x0/cpu.c
> create mode 100644 arch/m68k/cpu/m680x0/start.S
> create mode 100644 arch/m68k/cpu/m680x0/u-boot.lds
> create mode 100644 arch/m68k/include/asm/bootinfo.h
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 34081769ecd..9fff8989684 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -1324,6 +1324,12 @@ F: lib/getopt.c
> F: test/log/
> F: test/py/tests/test_log.py
>
> +M680X0 ARCHITECTURE
> +M: Kuan-Wei Chiu <visitorckw at gmail.com>
> +S: Maintained
> +F: arch/m68k/cpu/m680x0/
> +F: arch/m68k/include/asm/bootinfo.h
> +
> MALI DISPLAY PROCESSORS
> M: Liviu Dudau <liviu.dudau at foss.arm.com>
> S: Supported
> diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig
> index 8ade6f7b9d1..f5c0dc037b4 100644
> --- a/arch/m68k/Kconfig
> +++ b/arch/m68k/Kconfig
> @@ -12,50 +12,64 @@ config MCF520x
> select OF_CONTROL
> select DM
> select DM_SERIAL
> + select ARCH_COLDFIRE
> bool
>
> config MCF52x2
> select OF_CONTROL
> select DM
> select DM_SERIAL
> + select ARCH_COLDFIRE
> bool
>
> config MCF523x
> select OF_CONTROL
> select DM
> select DM_SERIAL
> + select ARCH_COLDFIRE
> bool
>
> config MCF530x
> select OF_CONTROL
> select DM
> select DM_SERIAL
> + select ARCH_COLDFIRE
> bool
>
> config MCF5301x
> select OF_CONTROL
> select DM
> select DM_SERIAL
> + select ARCH_COLDFIRE
> bool
>
> config MCF532x
> select OF_CONTROL
> select DM
> select DM_SERIAL
> + select ARCH_COLDFIRE
> bool
>
> config MCF537x
> select OF_CONTROL
> select DM
> select DM_SERIAL
> + select ARCH_COLDFIRE
> bool
>
> config MCF5441x
> select OF_CONTROL
> select DM
> select DM_SERIAL
> + select ARCH_COLDFIRE
> bool
>
> +config M680x0
> + bool
> + help
> + This enables support for the classic Motorola 68000 family of
> + processors.
> +
> # processor type
> config M5208
> bool
> @@ -110,6 +124,10 @@ config M54418
> bool
> select MCF5441x
>
> +config M68040
> + bool
> + select M680x0
> +
> # peripherals
> config CF_DSPI
> bool
> @@ -178,6 +196,18 @@ config TARGET_STMARK2
>
> endchoice
>
> +config SYS_CPU
> + string
> + default "mcf52x2" if MCF52x2
> + default "mcf523x" if MCF523x
> + default "mcf530x" if MCF530x
> + default "mcf532x" if MCF532x
> + default "mcf5445x" if MCF5445x
> + default "m680x0" if M680x0
> +
> +config ARCH_COLDFIRE
> + bool
> +
> source "board/BuS/eb_cpu5282/Kconfig"
> source "board/cobra5272/Kconfig"
> source "board/freescale/m5208evbe/Kconfig"
> diff --git a/arch/m68k/Makefile b/arch/m68k/Makefile
> index 4a7960bbeb4..bb57cf9ac63 100644
> --- a/arch/m68k/Makefile
> +++ b/arch/m68k/Makefile
> @@ -17,6 +17,7 @@ cpuflags-$(CONFIG_M5307) := -mcpu=5307
> cpuflags-$(CONFIG_MCF5301x) := -mcpu=53015 -fPIC
> cpuflags-$(CONFIG_MCF532x) := -mcpu=5329 -fPIC
> cpuflags-$(CONFIG_MCF5441x) := -mcpu=54418 -fPIC
> +cpuflags-$(CONFIG_M68040) := -mcpu=68040 -fno-pic
>
> PLATFORM_CPPFLAGS += $(cpuflags-y)
>
> diff --git a/arch/m68k/config.mk b/arch/m68k/config.mk
> index 643b7d1d35d..458953f9712 100644
> --- a/arch/m68k/config.mk
> +++ b/arch/m68k/config.mk
> @@ -3,8 +3,14 @@
> # (C) Copyright 2000-2002
> # Wolfgang Denk, DENX Software Engineering, wd at denx.de.
>
> -PLATFORM_CPPFLAGS += -D__M68K__ -fPIC
> +PLATFORM_CPPFLAGS += -D__M68K__
> +ifneq ($(CONFIG_M680x0),y)
> +PLATFORM_CPPFLAGS += -fPIC
> +endif
> KBUILD_LDFLAGS += -n -pie
> PLATFORM_RELFLAGS += -ffunction-sections -fdata-sections
> -PLATFORM_RELFLAGS += -ffixed-d7 -msep-data
> +PLATFORM_RELFLAGS += -ffixed-d7
> +ifneq ($(CONFIG_M680x0),y)
> +PLATFORM_RELFLAGS += -msep-data
> +endif
> LDFLAGS_FINAL += --gc-sections -pie
> diff --git a/arch/m68k/cpu/m680x0/Makefile b/arch/m68k/cpu/m680x0/Makefile
> new file mode 100644
> index 00000000000..f6e0c9a46c0
> --- /dev/null
> +++ b/arch/m68k/cpu/m680x0/Makefile
> @@ -0,0 +1,6 @@
> +# SPDX-License-Identifier: GPL-2.0-or-later
> +#
> +# Copyright (C) 2025, Kuan-Wei Chiu <visitorckw at gmail.com>
> +
> +extra-y += start.o
> +obj-y += cpu.o
> diff --git a/arch/m68k/cpu/m680x0/cpu.c b/arch/m68k/cpu/m680x0/cpu.c
> new file mode 100644
> index 00000000000..f60b932c7dd
> --- /dev/null
> +++ b/arch/m68k/cpu/m680x0/cpu.c
> @@ -0,0 +1,73 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * CPU specific code for m68040
> + *
> + * Copyright (C) 2025, Kuan-Wei Chiu <visitorckw at gmail.com>
> + */
> +
> +#include <config.h>
> +#include <cpu_func.h>
> +#include <init.h>
> +#include <stdio.h>
> +#include <asm/global_data.h>
> +#include <linux/types.h>
> +
> +DECLARE_GLOBAL_DATA_PTR;
> +
> +void m68k_virt_init_reserve(ulong base)
> +{
> + struct global_data *gd_ptr = (struct global_data *)base;
> + char *p = (char *)gd_ptr;
> + unsigned int i;
> +
> + /* FIXME: usage of memset() here caused a hang on QEMU m68k virt. */
> + for (i = 0; i < sizeof(*gd_ptr); i++)
> + p[i] = 0;
> +
> + gd = gd_ptr;
> +
> + gd->malloc_base = base + sizeof(*gd_ptr);
> +}
> +
> +int print_cpuinfo(void)
> +{
> + puts("CPU: M68040 (QEMU Virt)\n");
> +
> + return 0;
> +}
> +
> +int get_clocks(void)
> +{
> + return 0;
> +}
> +
> +int cpu_init_r(void)
> +{
> + return 0;
> +}
> +
> +/*
> + * Relocation Stub
> + * We skip actual relocation for this QEMU bring-up and jump directly
> + * to board_init_r.
> + */
> +
> +void relocate_code(ulong sp, struct global_data *new_gd, ulong relocaddr)
> +{
> + board_init_r(new_gd, relocaddr);
> +}
> +
> +/* Stubs for Standard Facilities (Cache, Interrupts) */
> +
> +int disable_interrupts(void) { return 0; }
> +void enable_interrupts(void) { return; }
> +int interrupt_init(void) { return 0; }
> +
> +void icache_enable(void) {}
> +void icache_disable(void) {}
> +int icache_status(void) { return 0; }
> +void dcache_enable(void) {}
> +void dcache_disable(void) {}
> +int dcache_status(void) { return 0; }
> +void flush_cache(unsigned long start, unsigned long size) {}
> +void flush_dcache_range(unsigned long start, unsigned long stop) {}
> diff --git a/arch/m68k/cpu/m680x0/start.S b/arch/m68k/cpu/m680x0/start.S
> new file mode 100644
> index 00000000000..0802ca1fca2
> --- /dev/null
> +++ b/arch/m68k/cpu/m680x0/start.S
> @@ -0,0 +1,73 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +/*
> + * Startup code for m68040
> + *
> + * Copyright (C) 2025, Kuan-Wei Chiu <visitorckw at gmail.com>
> + */
> +
> +#include <asm-offsets.h>
> +#include <config.h>
> +#include <linux/linkage.h>
> +
> +.section .text
> +
> +/*
> + * Vector Table
> + * m68k uses the first 1KB for the exception vector table.
> + */
> +.balign 4
> +.global _vectors
> +_vectors:
> + .long CFG_SYS_INIT_SP_ADDR /* 0x00: Initial SP */
> + .long _start /* 0x04: Initial PC (Reset) */
> + .long _fault /* 0x08: Bus Error */
> + .long _fault /* 0x0C: Address Error */
> + .long _fault /* 0x10: Illegal Instruction */
> + .long _fault /* 0x14: Zero Divide */
> + .long _fault /* 0x18: CHK */
> + .long _fault /* 0x1C: TRAPV */
> + .long _fault /* 0x20: Privilege */
> + .long _fault /* 0x24: Trace */
> + .long _fault /* 0x28: Line 1010 */
> + .long _fault /* 0x2C: Line 1111 */
> + .fill 0x400 - (.-_vectors), 1, 0
> +
> +/*
> + * Entry Point
> + */
> +ENTRY(_start)
> + /* Disable Interrupts */
> + move.w #0x2700, %sr
> +
> + /* Setup initial stack pointer */
> + move.l #CFG_SYS_INIT_SP_ADDR, %sp
> +
> + /*
> + * Allocate Global Data (GD)
> + * board_init_f_alloc_reserve(top) returns the new top of stack in %d0
> + */
> + move.l %sp, -(%sp)
> + bsr.l board_init_f_alloc_reserve
> + addq.l #4, %sp
> +
> + /* Update Stack Pointer and set GD register */
> + move.l %d0, %sp
> + move.l %d0, %d7 /* %d7 is the gd register */
> +
> + /* Initialize Reserved Memory. */
> + move.l %d0, -(%sp)
> + bsr.l m68k_virt_init_reserve
> + addq.l #4, %sp
> +
> + /* Enter board_init_f(0) */
> + clr.l -(%sp)
> + bsr.l board_init_f
> + addq.l #4, %sp
> +
> + /* Should not return */
> +hang:
> + bra.s hang
> +ENDPROC(_start)
> +
> +_fault:
> + bra.s _fault
> diff --git a/arch/m68k/cpu/m680x0/u-boot.lds b/arch/m68k/cpu/m680x0/u-boot.lds
> new file mode 100644
> index 00000000000..ae102c32833
> --- /dev/null
> +++ b/arch/m68k/cpu/m680x0/u-boot.lds
> @@ -0,0 +1,47 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Linker Script for m68040
> + *
> + * Copyright (C) 2025, Kuan-Wei Chiu <visitorckw at gmail.com>
> + */
> +
> +OUTPUT_ARCH(m68k)
> +ENTRY(_start)
> +
> +SECTIONS
> +{
> + . = 0x00000000;
> + __text_start = .;
> +
> + .text :
> + {
> + arch/m68k/cpu/m680x0/start.o (.text*)
> + *(.text*)
> + }
> +
> + . = ALIGN(16);
> + .rodata : { *(.rodata*) }
> +
> + . = ALIGN(16);
> + .data : { *(.data*) }
> +
> + . = ALIGN(4);
> + .u_boot_list : {
> + KEEP(*(SORT(*u_boot_list*)));
> + }
> +
> + . = ALIGN(4);
> + __image_copy_end = .;
> + __init_end = .;
> +
> + . = ALIGN(16);
> + __bss_start = .;
> + .bss :
> + {
> + *(.bss*)
> + . = ALIGN(16);
> + }
> + __bss_end = .;
> +
> + _end = .;
> +}
> diff --git a/arch/m68k/include/asm/bootinfo.h b/arch/m68k/include/asm/bootinfo.h
> new file mode 100644
> index 00000000000..6d7bde3b833
> --- /dev/null
> +++ b/arch/m68k/include/asm/bootinfo.h
> @@ -0,0 +1,39 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +/*
> + * Copyright (C) 2025, Kuan-Wei Chiu <visitorckw at gmail.com>
> + *
> + * Definitions for the m68k bootinfo interface.
> + */
> +
> +#ifndef _ASM_M68K_BOOTINFO_H
> +#define _ASM_M68K_BOOTINFO_H
> +
> +#ifndef __ASSEMBLY__
> +
> +struct bi_record {
> + unsigned short tag; /* tag ID */
> + unsigned short size; /* size of record (in bytes) */
> + unsigned long data[0]; /* data */
> +};
> +
> +#endif /* __ASSEMBLY__ */
> +
> +/* Bootinfo Tag IDs */
> +#define BI_LAST 0x0000
> +#define BI_MACHTYPE 0x0001
> +#define BI_CPUTYPE 0x0002
> +#define BI_FPUTYPE 0x0003
> +#define BI_MMUTYPE 0x0004
> +#define BI_MEMCHUNK 0x0005
> +#define BI_RAMDISK 0x0006
> +#define BI_COMMAND_LINE 0x0007
> +
> +/* QEMU virt specific tags */
> +#define BI_VIRT_QEMU_VERSION 0x8000
> +#define BI_VIRT_GF_PIC_BASE 0x8001
> +#define BI_VIRT_GF_RTC_BASE 0x8002
> +#define BI_VIRT_GF_TTY_BASE 0x8003
> +#define BI_VIRT_VIRTIO_BASE 0x8004
> +#define BI_VIRT_CTRL_BASE 0x8005
> +
> +#endif /* _ASM_M68K_BOOTINFO_H */
> diff --git a/arch/m68k/lib/Makefile b/arch/m68k/lib/Makefile
> index 6e1fd938f52..cf93715637a 100644
> --- a/arch/m68k/lib/Makefile
> +++ b/arch/m68k/lib/Makefile
> @@ -7,10 +7,5 @@
> ## if the user asked for it
> lib-$(CONFIG_USE_PRIVATE_LIBGCC) += lshrdi3.o muldi3.o ashldi3.o ashrdi3.o
>
> -obj-y += bdinfo.o
> obj-$(CONFIG_CMD_BOOTM) += bootm.o
> -obj-y += cache.o
> -obj-y += interrupts.o
> -obj-y += time.o
> -obj-y += traps.o
> -obj-y += fec.o
> +obj-$(CONFIG_ARCH_COLDFIRE) += cache.o interrupts.o time.o traps.o bdinfo.o fec.o
-- Angelo
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