linux-kernel - Re: [PATCH 2/2] powerpc/8xx: Add microcode patch to move SMC parameter RAM.

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Date:   Tue, 14 May 2019 10:31:32 +0200
From:   Christophe Leroy <christophe.leroy@....fr>
To:     Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Vitaly Bordug <vitb@...nel.crashing.org>,
        Scott Wood <oss@...error.net>
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH 2/2] powerpc/8xx: Add microcode patch to move SMC
 parameter RAM.



Le 14/05/2019 à 08:56, Michael Ellerman a écrit :
> Christophe Leroy <christophe.leroy@....fr> writes:
> 
>> Some SCC functions like the QMC requires an extended parameter RAM.
>> On modern 8xx (ie 866 and 885), SPI area can already be relocated,
>> allowing the use of those functions on SCC2. But SCC3 and SCC4
>> parameter RAM collide with SMC1 and SMC2 parameter RAMs.
>>
>> This patch adds microcode to allow the relocation of both SMC1 and
>> SMC2, and relocate them at offsets 0x1ec0 and 0x1fc0.
>> Those offsets are by default for the CPM1 DSP1 and DSP2, but there
>> is no kernel driver using them at the moment so this area can be
>> reused.
>>
>> Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
>> ---
>>   arch/powerpc/platforms/8xx/Kconfig      |   7 ++
>>   arch/powerpc/platforms/8xx/micropatch.c | 109 +++++++++++++++++++++++++++++++-
>>   2 files changed, 114 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/powerpc/platforms/8xx/micropatch.c b/arch/powerpc/platforms/8xx/micropatch.c
>> index 33a9042fca80..dc4423daf7d4 100644
>> --- a/arch/powerpc/platforms/8xx/micropatch.c
>> +++ b/arch/powerpc/platforms/8xx/micropatch.c
>> @@ -622,6 +622,86 @@ static uint patch_2f00[] __initdata = {
>>   };
>>   #endif
>>   
>> +/*
>> + * SMC relocation patch arrays.
>> + */
>> +
>> +#ifdef CONFIG_SMC_UCODE_PATCH
>> +
>> +static uint patch_2000[] __initdata = {
>> +	0x3fff0000, 0x3ffd0000, 0x3ffb0000, 0x3ff90000,
>> +	0x5fefeff8, 0x5f91eff8, 0x3ff30000, 0x3ff10000,
>> +	0x3a11e710, 0xedf0ccb9, 0xf318ed66, 0x7f0e5fe2,
> 
> Do we have any doc on what these values are?

No we don't


> 
> I get that it's microcode but do we have any more detail than that?
> What's the source etc?
> 

There is an Engineering Bulletin (EB662) dated 2006 from Freescale which 
slightly describe things and there are associated S-Record files 
containing those values.

And an old related message in the mailing list 
https://www.mail-archive.com/linuxppc-dev@lists.ozlabs.org/msg46038.html

Christophe