[PATCH 4/4] ARM: mvebu: returns ll_get_cpuid() to ll_get_coherency_cpumask()

[Thomas Petazzoni]

Hello Jason,

There is a typo in the title of this commit: s/returns/rename/.

Should I respin this patch, or can you fix directly in mvebu/soc ?

Thanks, and sorry for the mess :/

Thomas

On Thu, 22 May 2014 14:48:02 +0200, Thomas Petazzoni wrote:
> In the refactoring of the coherency fabric assembly code, a function
> called ll_get_cpuid() was created to factorize common logic between
> functions adding CPU to the SMP coherency group, enabling and
> disabling the coherency.
> 
> However, the name of the function is highly misleading: ll_get_cpuid()
> makes one think tat it returns the ID of the CPU, i.e 0 for CPU0, 1
> for CPU1, etc. In fact, this is not at all what this function returns:
> it returns a CPU mask for the current CPU, usable for the coherency
> fabric configuration and control registers.
> 
> Therefore this commit renames this function to
> ll_get_coherency_cpumask(), and adds additional comments on top of the
> function to explain in more details what it does, and also how the
> endianess issue is handled.
> 
> Signed-off-by: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
> ---
>  arch/arm/mach-mvebu/coherency_ll.S | 43 ++++++++++++++++++++++----------------
>  1 file changed, 25 insertions(+), 18 deletions(-)
> 
> diff --git a/arch/arm/mach-mvebu/coherency_ll.S b/arch/arm/mach-mvebu/coherency_ll.S
> index 311442a..510c29e 100644
> --- a/arch/arm/mach-mvebu/coherency_ll.S
> +++ b/arch/arm/mach-mvebu/coherency_ll.S
> @@ -49,15 +49,22 @@ ENTRY(ll_get_coherency_base)
>  	mov	pc, lr
>  ENDPROC(ll_get_coherency_base)
>  
> -/* Returns the CPU ID in r3 (r0 is untouched) */
> -ENTRY(ll_get_cpuid)
> +/*
> + * Returns the coherency CPU mask in r3 (r0 is untouched). This
> + * coherency CPU mask can be used with the coherency fabric
> + * configuration and control registers. Note that the mask is already
> + * endian-swapped as appropriate so that the calling functions do not
> + * have to care about endianness issues while accessing the coherency
> + * fabric registers
> + */
> +ENTRY(ll_get_coherency_cpumask)
>  	mrc	15, 0, r3, cr0, cr0, 5
>  	and	r3, r3, #15
>  	mov	r2, #(1 << 24)
>  	lsl	r3, r2, r3
>  ARM_BE8(rev	r3, r3)
>  	mov	pc, lr
> -ENDPROC(ll_get_cpuid)
> +ENDPROC(ll_get_coherency_cpumask)
>  
>  /*
>   * ll_add_cpu_to_smp_group(), ll_enable_coherency() and
> @@ -71,14 +78,14 @@ ENDPROC(ll_get_cpuid)
>  ENTRY(ll_add_cpu_to_smp_group)
>  	/*
>  	 * As r0 is not modified by ll_get_coherency_base() and
> -	 * ll_get_cpuid(), we use it to temporarly save lr and avoid
> -	 * it being modified by the branch and link calls. This
> -	 * function is used very early in the secondary CPU boot, and
> -	 * no stack is available at this point.
> +	 * ll_get_coherency_cpumask(), we use it to temporarly save lr
> +	 * and avoid it being modified by the branch and link
> +	 * calls. This function is used very early in the secondary
> +	 * CPU boot, and no stack is available at this point.
>  	 */
>  	mov 	r0, lr
>  	bl	ll_get_coherency_base
> -	bl	ll_get_cpuid
> +	bl	ll_get_coherency_cpumask
>  	mov 	lr, r0
>  	add	r0, r1, #ARMADA_XP_CFB_CFG_REG_OFFSET
>  1:
> @@ -93,14 +100,14 @@ ENDPROC(ll_add_cpu_to_smp_group)
>  ENTRY(ll_enable_coherency)
>  	/*
>  	 * As r0 is not modified by ll_get_coherency_base() and
> -	 * ll_get_cpuid(), we use it to temporarly save lr and avoid
> -	 * it being modified by the branch and link calls. This
> -	 * function is used very early in the secondary CPU boot, and
> -	 * no stack is available at this point.
> +	 * ll_get_coherency_cpumask(), we use it to temporarly save lr
> +	 * and avoid it being modified by the branch and link
> +	 * calls. This function is used very early in the secondary
> +	 * CPU boot, and no stack is available at this point.
>  	 */
>  	mov r0, lr
>  	bl	ll_get_coherency_base
> -	bl	ll_get_cpuid
> +	bl	ll_get_coherency_cpumask
>  	mov lr, r0
>  	add	r0, r1, #ARMADA_XP_CFB_CTL_REG_OFFSET
>  1:
> @@ -117,14 +124,14 @@ ENDPROC(ll_enable_coherency)
>  ENTRY(ll_disable_coherency)
>  	/*
>  	 * As r0 is not modified by ll_get_coherency_base() and
> -	 * ll_get_cpuid(), we use it to temporarly save lr and avoid
> -	 * it being modified by the branch and link calls. This
> -	 * function is used very early in the secondary CPU boot, and
> -	 * no stack is available at this point.
> +	 * ll_get_coherency_cpumask(), we use it to temporarly save lr
> +	 * and avoid it being modified by the branch and link
> +	 * calls. This function is used very early in the secondary
> +	 * CPU boot, and no stack is available at this point.
>  	 */
>  	mov 	r0, lr
>  	bl	ll_get_coherency_base
> -	bl	ll_get_cpuid
> +	bl	ll_get_coherency_cpumask
>  	mov 	lr, r0
>  	add	r0, r1, #ARMADA_XP_CFB_CTL_REG_OFFSET
>  1:



-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com