[PATCH 3/5] ARM: l2x0: Errata fix for flush by Way operation can cause data corruption

[Andrei Warkentin]

On Sat, Feb 12, 2011 at 11:59 AM, Santosh Shilimkar
<santosh.shilimkar at ti.com> wrote:
>> -----Original Message-----
>> From: Andrei Warkentin [mailto:andreiw at motorola.com]
>> Sent: Saturday, February 12, 2011 11:20 PM
>> To: Santosh Shilimkar
>> Cc: linux-omap at vger.kernel.org; khilman at ti.com; tony at atomide.com;
>> linux-arm-kernel at lists.infradead.org; Catalin Marinas
>> Subject: Re: [PATCH 3/5] ARM: l2x0: Errata fix for flush by Way
>> operation can cause data corruption
>>
> [....]
>
>>
>> Can these PL310 errata fixes be made more generic? PL310 is present
>> in
>> non-OMAP platforms too, which lack the TI hypervisor. And these
>> platforms might have the same PL310 rev, and suffer the same
>> glitches.
>> While ideally there is some kind of hypervisor_ops to modify the
>> protected register, at the very least there should be the generic
>> debug_write handling the  "I  can write all PL310 regs" case. If
>> you're interested I have a patch someplace that tried to do this,
>> hopefully I can still find it.
>
> They are kind of generic. If you look at it, the only change
> Which is arch specific is the implementation of "debug_writel" function.
> Today this code is not in generic PL310 code, but
> OMAP specific.
>
> May be we can make this as exported function pointer, which
> arch's can populate.
>
> Will that work for you ?
>
> Regards,
> Santosh
>

Ie something like the following.... what do you think???

#define L2X0_DCR (0xF40)

static void debug_writel(unsigned long val)
{
#ifdef CONFIG_ARCH_OMAP4
       omap_smc1(0x100, val);
#else
       writel_relaxed(val, l2x0_base + L2X0_DCR);
#endif
}
...
...

       /* clean all ways */
       spin_lock_irqsave(&l2x0_lock, flags);
#ifdef CONFIG_PL310_ERRATA_727915
       debug_writel(DCR_DWB | DCR_DCL); <---- not 0x3, but self-documenting
#endif
       writel_relaxed(l2x0_way_mask, l2x0_base + L2X0_CLEAN_INV_WAY);
       cache_wait_way(l2x0_base + L2X0_CLEAN_INV_WAY, l2x0_way_mask);
       cache_sync();
#ifdef CONFIG_PL310_ERRATA_727915
       debug_writel(0x00);
#endif
       spin_unlock_irqrestore(&l2x0_lock, flags);