Re: [PATCH v2 3/3] ARM: OMAP2+: AM43x: L2 cache support

[Sekhar Nori <nsekhar@ti.com>]

On Thursday 10 April 2014 05:33 PM, Russell King - ARM Linux wrote:
> On Thu, Apr 10, 2014 at 05:26:15PM +0530, Sekhar Nori wrote:
>> On Wednesday 09 April 2014 09:53 PM, Russell King - ARM Linux wrote:
>>> That is required because as part of the enable sequence, we write to the
>>> lockdown registers to clear out anything that may be there before we
>>> enable the L2 cache.  If we didn't set the NS lockdown bit, then we
>>> would need the secure monitor to do it for us.
>>
>> And I realized yesterday that the only reason L2C is working on AM437x
>> is because AM437x ROM is setting these bits up for us.
>>
>>> Both of these bits should be managed within the L2C code rather than by
>>> platforms.
>>
>> The current L2C code is not managing the NS_LOCKDOWN bit. I can take a
>> shot at adding this support unless you are already looking at it.
> 
> True, and I'm aware that it's missing.  So... how about this on top
> of my series so far.  We can deal with L310_AUX_CTRL_NS_INT_CTRL when
> the need to access those registers arises (if/when the edac driver
> is submitted.)
> 
> diff --git a/arch/arm/mach-omap2/omap4-common.c b/arch/arm/mach-omap2/omap4-common.c
> index c0f9a81a2d32..4a494cde8367 100644
> --- a/arch/arm/mach-omap2/omap4-common.c
> +++ b/arch/arm/mach-omap2/omap4-common.c
> @@ -213,8 +213,6 @@ static int __init omap_l2_cache_init(void)
>  
>  	/* 16-way associativity, parity disabled, way size - 64KB (es2.0 +) */
>  	aux_ctrl = L310_AUX_CTRL_CACHE_REPLACE_RR |
> -		   L310_AUX_CTRL_NS_LOCKDOWN |
> -		   L310_AUX_CTRL_NS_INT_CTRL |
>  		   L2C_AUX_CTRL_SHARED_OVERRIDE |
>  		   L310_AUX_CTRL_DATA_PREFETCH |
>  		   L310_AUX_CTRL_INSTR_PREFETCH;
> diff --git a/arch/arm/mm/cache-l2x0.c b/arch/arm/mm/cache-l2x0.c
> index 98796b789eb9..837f384c1d51 100644
> --- a/arch/arm/mm/cache-l2x0.c
> +++ b/arch/arm/mm/cache-l2x0.c
> @@ -776,6 +776,13 @@ static void __init l2c310_enable(void __iomem *base, u32 aux, unsigned num_lock)
>  			power_ctrl & L310_STNDBY_MODE_EN ? "en" : "dis");
>  	}
>  
> +	/*
> +	 * Always enable non-secure access to the lockdown registers -
> +	 * we write to them as part of the L2C enable sequence so they
> +	 * need to be accessible.
> +	 */
> +	aux |= L310_AUX_CTRL_NS_LOCKDOWN;
> +

This will work. NS_LOCKDOWN is required for L2C-220 as well and so I was
thinking about adding a new l2c220_enable() which will set the
NS_LOCKDOWN and then call l2c_enable()

Thanks,
Sekhar