[U-Boot] [PATCH] mx6: Set shared override bit in PL310 AUX_CTRL register

[Nishanth Menon]

On 03/12/2015 09:25 AM, Fabio Estevam wrote:
> Tom/Nishanth,
> 
> On Thu, Mar 12, 2015 at 10:57 AM, Fabio Estevam <festevam at gmail.com> wrote:
>> On Thu, Mar 12, 2015 at 10:41 AM, Tom Rini <trini at konsulko.com> wrote:
>>
>>> We should put this somewhere a bit more common that other A9 cores can
>>> also call into like OMAP4, SoCFPGA and maybe zynq later (based on a
>>> quick git grep pl310).
>>
>> I thought about it as well, but I didn't find a suitable common place
>> for putting it.
>>
>> Suggestions? Thanks
> 
> What about this?
> 
> diff --git a/arch/arm/cpu/armv7/cache_v7.c b/arch/arm/cpu/armv7/cache_v7.c
> index 0f9d837..e3335f2 100644
> --- a/arch/arm/cpu/armv7/cache_v7.c
> +++ b/arch/arm/cpu/armv7/cache_v7.c
> @@ -8,6 +8,7 @@
>  #include <linux/types.h>
>  #include <common.h>
>  #include <asm/armv7.h>
> +#include <asm/pl310.h>
>  #include <asm/utils.h>
> 
>  #define ARMV7_DCACHE_INVAL_ALL        1
> @@ -274,8 +275,25 @@ void flush_dcache_range(unsigned long start,
> unsigned long stop)
>      v7_outer_cache_flush_range(start, stop);
>  }
> 
> +#ifdef CONFIG_SYS_L2_PL310
> +static void pl310_set_override(void)
> +{
> +    struct pl310_regs *const pl310 = (struct pl310_regs *)L2_PL310_BASE;
> +
> +    /*
> +     * Set bit 22 in the auxiliary control register. If this bit
> +     * is cleared, PL310 treats Normal Shared Non-cacheable
> +     * accesses as Cacheable no-allocate.
> +     */
> +    setbits_le32(&pl310->pl310_aux_ctrl, L310_SHARED_ATT_OVERRIDE_ENABLE);

I dont think this works for OMAP4 (which also uses A9, PL310) - we use
an smc #0 with service 0x109 (I have to reconfirm) to set l2 aux_ctrl.

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/arch/arm/mach-omap2/omap4-common.c#n178

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/arch/arm/mach-omap2/omap-secure.h#n44

we might want to ensure that:
a) The "setting" part of things get into a weak function with default
function that may be SoC dependent if needed
b) there be revision checks as needed to add this.
c) each configuration be adequately isolated perhaps?

> +}
> +#endif
> +
>  void arm_init_before_mmu(void)
>  {
> +#ifdef CONFIG_SYS_L2_PL310
> +    pl310_set_override();
> +#endif
>      v7_outer_cache_enable();
>      invalidate_dcache_all();
>      v7_inval_tlb();
> diff --git a/arch/arm/include/asm/pl310.h b/arch/arm/include/asm/pl310.h
> index ddc245b..de7650e 100644
> --- a/arch/arm/include/asm/pl310.h
> +++ b/arch/arm/include/asm/pl310.h
> @@ -16,6 +16,8 @@
>  #define L2X0_STNDBY_MODE_EN            (1 << 0)
>  #define L2X0_CTRL_EN                1
> 
> +#define L310_SHARED_ATT_OVERRIDE_ENABLE        (1 << 22)
> +
>  struct pl310_regs {
>      u32 pl310_cache_id;
>      u32 pl310_cache_type;
> 


-- 
Regards,
Nishanth Menon