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

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Message-ID: <87a7fptth7.fsf@concordia.ellerman.id.au>
Date:   Tue, 14 May 2019 16:56:04 +1000
From:   Michael Ellerman <mpe@...erman.id.au>
To:     Christophe Leroy <christophe.leroy@....fr>,
        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.

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?

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

cheers