[U-Boot] [PATCH v2 1/3] serial: Support an early UART for debugging

[Simon Glass]

On 26 January 2015 at 18:27, Simon Glass <sjg at chromium.org> wrote:
> This came up in a discussion on the mailing list here:
>
> https://patchwork.ozlabs.org/patch/384613/
>
> My concerns at the time were:
> - it doesn't need to be written in assembler
> - it doesn't need to be ARM-specific
>
> This patch provides a possible alternative. It works by allowing any serial
> driver to export one init function and provide a putc() function. These
> can be used to output debug data before the real serial driver is available.
>
> This implementation does not depend on driver model, and it is possible for
> it to operate without a stack on some architectures (e.g. PowerPC, ARM). It
> provides the same features as the ARM-specific debug.S but with more UART
> and architecture support.
>
> Signed-off-by: Simon Glass <sjg at chromium.org>
> ---
>
> Changes in v2:
> - Add asmlinkage to exported functions
>
>  drivers/serial/Kconfig |  46 ++++++++++++++++
>  include/debug_uart.h   | 139 +++++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 185 insertions(+)
>  create mode 100644 include/debug_uart.h
>

As discussed let's bring this in.

Applied to u-boot-dm.

(Removed these Kconfig options from minnowmax_defconfig as the same
time to avoid a build error. We can always enable it later)