[PATCH 1/3] ARM: debug: use kconfig choice for selecting DEBUG_LL UART

[Shawn Guo]

On Tue, Aug 16, 2011 at 10:41:11PM +0100, Will Deacon wrote:
> Enabling CONFIG_DEBUG_LL (which is required for earlyprintk) hardwires
> the debug UART address into the kernel, so that we can print before the
> platform is initialised.
> 
> If the user inadvertently selects multiple platforms with DEBUG_LL
> enabled, the UART address may not be correct and will likely cause the
> kernel to hang in the very early stages of boot.
> 
> This patch, based on a skeleton from Russell, uses a Kconfig choice for
> selecting the DEBUG_LL UART, therefore allowing the user to make a
> choice about the supported platform when DEBUG_LL is enabled.
> 
> Cc: Linus Walleij <linus.walleij at stericsson.com>
> Signed-off-by: Will Deacon <will.deacon at arm.com>
> ---
>  arch/arm/Kconfig.debug |   41 ++++++++++++++++++++++++-----------------
>  1 files changed, 24 insertions(+), 17 deletions(-)
> 
> diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug
> index 81cbe40..11604c9 100644
> --- a/arch/arm/Kconfig.debug
> +++ b/arch/arm/Kconfig.debug
> @@ -72,6 +72,30 @@ config DEBUG_LL
>  	  in the kernel.  This is helpful if you are debugging code that
>  	  executes before the console is initialized.
>  
> +choice
> +	prompt "Kernel low-level debugging port"
> +	depends on DEBUG_LL
> +
> +	config DEBUG_DC21285_PORT
> +		bool "Kernel low-level debugging messages via footbridge serial port"
> +		depends on FOOTBRIDGE
> +		help
> +		  Say Y here if you want the debug print routines to direct
> +		  their output to the serial port in the DC21285 (Footbridge).
> +		  Saying N will cause the debug messages to appear on the first
> +		  16550 serial port.
> +
> +	config DEBUG_CLPS711X_UART2

I would expect this will become a long list when other platforms start
adding CONFIG symbol here.  It may be a good idea to sort this list
in symbol from the beginning.

Regards,
Shawn

> +		bool "Kernel low-level debugging messages via UART2"
> +		depends on ARCH_CLPS711X
> +		help
> +		  Say Y here if you want the debug print routines to direct
> +		  their output to the second serial port on these devices.
> +		  Saying N will cause the debug messages to appear on the first
> +		  serial port.
> +
> +endchoice
> +
>  config EARLY_PRINTK
>  	bool "Early printk"
>  	depends on DEBUG_LL
> @@ -100,23 +124,6 @@ config OC_ETM
>  	  buffer driver that will allow you to collect traces of the
>  	  kernel code.
>  
> -config DEBUG_DC21285_PORT
> -	bool "Kernel low-level debugging messages via footbridge serial port"
> -	depends on DEBUG_LL && FOOTBRIDGE
> -	help
> -	  Say Y here if you want the debug print routines to direct their
> -	  output to the serial port in the DC21285 (Footbridge). Saying N
> -	  will cause the debug messages to appear on the first 16550
> -	  serial port.
> -
> -config DEBUG_CLPS711X_UART2
> -	bool "Kernel low-level debugging messages via UART2"
> -	depends on DEBUG_LL && ARCH_CLPS711X
> -	help
> -	  Say Y here if you want the debug print routines to direct their
> -	  output to the second serial port on these devices.  Saying N will
> -	  cause the debug messages to appear on the first serial port.
> -
>  config DEBUG_S3C_UART
>  	depends on PLAT_SAMSUNG
>  	int "S3C UART to use for low-level debug"
> -- 
> 1.7.0.4