[PATCH 1/2] ARM: add diagnostic register access helpers

[Will Deacon]

On Tue, Apr 16, 2013 at 03:30:42PM +0100, Shawn Guo wrote:
> The CP15 diagnostic register holds many ARM errata bits.  Add a pair of
> access helpers for it.
> 
> Signed-off-by: Shawn Guo <shawn.guo at linaro.org>
> ---
>  arch/arm/include/asm/cp15.h |   13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 
> diff --git a/arch/arm/include/asm/cp15.h b/arch/arm/include/asm/cp15.h
> index 5ef4d80..0b14dfb 100644
> --- a/arch/arm/include/asm/cp15.h
> +++ b/arch/arm/include/asm/cp15.h
> @@ -82,6 +82,19 @@ static inline void set_copro_access(unsigned int val)
>  	isb();
>  }
>  
> +static inline unsigned int get_diag_reg(void)
> +{
> +	unsigned int val;
> +	asm("mrc p15, 0, %0, c15, c0, 1" : "=r" (val) : : "cc");
> +	return val;
> +}
> +
> +static inline void set_diag_reg(unsigned int val)
> +{
> +	asm volatile("mcr p15, 0, %0, c15, c0, 1" : : "r" (val) : "cc");
> +	isb();
> +}
> +

You don't want to poke this register with the MMU on, so I don't think this
patch is a very good idea.

Will