[PATCH v6 5/8] m68k: Add support for M68040 CPU

[Simon Glass]

On Wed, 7 Jan 2026 at 13:19, Kuan-Wei Chiu <visitorckw at gmail.com> 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
>

Reviewed-by: Simon Glass <simon.glass at canonical.com>