[RFC 1/7] ARM: vf610: add low level debug support for !MMU

[Stefan Agner]

Am 2014-10-12 20:48, schrieb Arnd Bergmann:
> On Sunday 12 October 2014 20:13:55 Stefan Agner wrote:
>> Add support for !MMU low level debug required for the secondary
>> Cortex-M4 core in Vybrid.
>>
>> Signed-off-by: Stefan Agner <stefan at agner.ch>
>> ---
>>  arch/arm/include/debug/vf.S | 10 ++++++++++
>>  1 file changed, 10 insertions(+)
>>
>> diff --git a/arch/arm/include/debug/vf.S b/arch/arm/include/debug/vf.S
>> index b889338..63c7ef7 100644
>> --- a/arch/arm/include/debug/vf.S
>> +++ b/arch/arm/include/debug/vf.S
>> @@ -17,12 +17,22 @@
>>
>>  #define VF_UART_VIRTUAL_BASE	0xfe000000
>>
>> +#ifdef CONFIG_MMU
>> +
>>  	.macro	addruart, rp, rv, tmp
>>  	ldr	\rp, =VF_UART_PHYSICAL_BASE 	@ physical
>>  	and	\rv, \rp, #0xffffff		@ offset within 16MB section
>>  	add	\rv, \rv, #VF_UART_VIRTUAL_BASE
>>  	.endm
>>
>> +#else /* !CONFIG_MMU */
>> +
>> +	.macro	addruart, rx, tmp
>> +	ldr	\rx, =(VF_UART_PHYSICAL_BASE)	@ physical
>> +	.endm
>> +
>> +#endif /* CONFIG_MMU */
>> +
>>  	.macro	senduart, rd, rx
>>  	strb	\rd, [\rx, #0x7]	@ Data Register
>>  	.endm
>>
> Hmm, I've previously needed to add this patch for randconfig testing:
> 
> index 78c91b5f97d4..ea9646cc2a0e 100644
> --- a/arch/arm/kernel/debug.S
> +++ b/arch/arm/kernel/debug.S
> @@ -35,7 +35,7 @@
>  
>  #else /* !CONFIG_MMU */
>                 .macro  addruart_current, rx, tmp1, tmp2
> -               addruart        \rx, \tmp1
> +               addruart        \rx, \tmp1, \tmp2
>                 .endm
>  
>  #endif /* CONFIG_MMU */
> 
> 
> 
> If we do this instead, could we avoid your patch?

Not completely, we then could just ifdef the base address, so it would
make it simpler. We could also pass a boolean in the third, currently
temporary argument to distinguish that during run time in order to get
rid of the compile time ifdef... 

--
Stefan