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From:   Kevin Hilman <khilman@baylibre.com>
To:     Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
        linux-remoteproc@vger.kernel.org, linux-amlogic@lists.infradead.org
Cc:     ohad@wizery.com, devicetree@vger.kernel.org,
        Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
        linux-kernel@vger.kernel.org, bjorn.andersson@linaro.org,
        robh+dt@kernel.org, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2 0/5] Amlogic Meson Always-On ARC remote-processor
 support
In-Reply-To: <20210102205904.2691120-1-martin.blumenstingl@googlemail.com>
References: <20210102205904.2691120-1-martin.blumenstingl@googlemail.com>
Date:   Mon, 25 Jan 2021 09:51:33 -0800
Message-ID: <7hmtwwx5ui.fsf@baylibre.com>
MIME-Version: 1.0
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Martin Blumenstingl <martin.blumenstingl@googlemail.com> writes:

> Amlogic Meson6/8/8b/8m2 come with an ARC core in the Always-On (AO)
> power-domain. This is typically used for waking up the ARM CPU after
> powering it down for system suspend.
>
> The exact ARC core used on Meson6 and earlier is not known. I believe
> it is an ARC625, but I am not sure about this. Meson8/8b/8m2 uses an
> ARC EM4 core.
> They all have in common that they use a section of the SoCs SRAM for
> running code on the ARC core.
>
> Unfortunately there's no information about the remote-processor control
> registers in the public Meson8b (S805) datasheet. All information is
> either taken from Amlogic's 3.10 kernel and 2011-03 u-boot or found by
> testing (for example the clock input is not mentioned anywhere in the
> reference code, but disabling it stops the AO ARC core from working).
>
> This series consists of five patches:
>  1: dt-bindings for the SRAM section
>  2: dt-bindings for the SECBUS2 syscon region which contains a few
>     bits for controlling this remote processor
>  3: dt-bindings for the AO ARC remote processor
>  4: the driver for booting code on the AO ARC remote processor
>  5: (only included for documentation purposes) dts changes (these will
>     be re-sent separately)
>
> Patches #3 and #4 should go through the remoteproc tree. Patches #1
> and #2 may go through Rob's (devicetree) tree, Kevin's linux-amlogic
> tree or through the remoteproc tree. Personally I have no preference
> here.
>
> To test this series I ported the Amlogic serial driver and added the
> board files for the Amlogic AO ARC EM4 to the Zephyr RTOS. The code can
> be found here: [0] (the resulting zephyr.elf can then be loaded as
> remote-processor firmware from Linux).
>
>
> Changes since v1 at [1]:
> - fixed yamllint warnings (after installing the package these now also
>   show up on my build machine) in patches #2 and #3. Thanks for the
>   hint Rob
> - dropped the explicit "select" statement from the dt-bindings in patch
>   #2 as suggested by Rob (thanks)
>
>
> [0] https://github.com/xdarklight/zephyr-rtos/commits/amlogic_ao_em4-20201229
> [1] https://patchwork.kernel.org/project/linux-amlogic/list/?series=407349
>
>
> Martin Blumenstingl (5):
>   dt-bindings: sram: Add compatible strings for the Meson AO ARC SRAM
>   dt-bindings: Amlogic: add the documentation for the SECBUS2 registers
>   dt-bindings: remoteproc: Add the documentation for Meson AO ARC rproc
>   remoteproc: meson-mx-ao-arc: Add a driver for the AO ARC remote
>     procesor
>   ARM: dts: meson: add the AO ARC remote processor

Patches 1-2, 5 queued for v5.12 via the amlogic tree.

Kevin