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SubjectRe: [PATCH v4 00/10] Allwinner sunxi message box support
Hello Samuel,

On Mon, Aug 19, 2019 at 10:23:01PM -0500, Samuel Holland wrote:
> This series adds support for the "hardware message box" in sun8i, sun9i,
> and sun50i SoCs, used for communication with the ARISC management
> processor (the platform's equivalent of the ARM SCP). The end goal is to
> use the arm_scpi driver as a client, communicating with firmware running
> on the AR100 CPU, or to use the mailbox to forward NMIs that the
> firmware picks up from R_INTC.
>
> Unfortunately, the ARM SCPI client no longer works with this driver
> since it now exposes all 8 hardware FIFOs individually. The SCPI client
> could be made to work (and I posted proof-of-concept code to that effect
> with v1 of this series), but that is a low priority, as Linux does not
> directly use SCPI with the current firmware version; all SCPI use goes
> through ATF via PSCI.
>
> As requested in the comments to v3 of this patchset, a demo client is
> provided in the final patch. This demo goes along with a toy firmware
> which shows that the driver does indeed work for two-way communication
> on all channels. To build the firmware component, run:

I've tried using this driver with mainline arm_scpi driver (which is probably
an expected future use, since crust provides SCPI interface).

The problem I've found is that arm_scpi expects message box to be
bi-directional, but this driver provides uni-directional interface.

What do you think about making this driver provide bi-directional interface?
We could halve the number of channels to 4 and mandate TX/RX configuration
(from main CPU's PoV) as ABI.

Otherwise it's impossible to use it with the arm_scpi driver.

Or do you have any other ideas? I guess arm_scpi can be fixed to add a
property that would make it possible to use single shmem with two
mailboxes, one for rx and one for tx, but making sun6i mailbox have
bi-directional interface sounds easier.

regards,
o.

> git clone https://github.com/crust-firmware/meta meta
> git clone -b mailbox-demo https://github.com/crust-firmware/crust meta/crust
> cd meta
> make
>
> That will by default produce a U-Boot + ATF + SCP firmware image in
> [meta/]build/pinebook/u-boot-sunxi-with-spl.bin. See the top-level
> README.md for more information, such as cross-compiler setup.
>
> I've now used this driver with three separate clients over the past two
> years, and they all work. If there are no remaining concerns with the
> driver, I'd like it to get merged.
>
> Even without the driver, the clock patches (1-2) can go in at any time.
>
> Changes from v3:
> - Rebased on sunxi-next
> - Added Rob's Reviewed-by for patch 3
> - Fixed a crash when receiving a message on a disabled channel
> - Cleaned up some comments/formatting in the driver
> - Fixed #mbox-cells in sunxi-h3-h5.dtsi (patch 7)
> - Removed the irqchip example (no longer relevant to the fw design)
> - Added a demo/example client that uses the driver and a toy firmware
>
> Changes from v2:
> - Merge patches 1-3
> - Add a comment in the code explaining the CLK_IS_CRITICAL usage
> - Add a patch to mark the AR100 clocks as critical
> - Use YAML for the device tree binding
> - Include a not-for-merge example usage of the mailbox
>
> Changes from v1:
> - Marked message box clocks as critical instead of hacks in the driver
> - 8 unidirectional channels instead of 4 bidirectional pairs
> - Use per-SoC compatible strings and an A31 fallback compatible
> - Dropped the mailbox framework patch
> - Include DT patches for SoCs that document the message box
>
> Samuel Holland (10):
> clk: sunxi-ng: Mark msgbox clocks as critical
> clk: sunxi-ng: Mark AR100 clocks as critical
> dt-bindings: mailbox: Add a sunxi message box binding
> mailbox: sunxi-msgbox: Add a new mailbox driver
> ARM: dts: sunxi: a80: Add msgbox node
> ARM: dts: sunxi: a83t: Add msgbox node
> ARM: dts: sunxi: h3/h5: Add msgbox node
> arm64: dts: allwinner: a64: Add msgbox node
> arm64: dts: allwinner: h6: Add msgbox node
> [DO NOT MERGE] drivers: firmware: msgbox demo
>
> .../mailbox/allwinner,sunxi-msgbox.yaml | 79 +++++
> arch/arm/boot/dts/sun8i-a83t.dtsi | 10 +
> arch/arm/boot/dts/sun9i-a80.dtsi | 10 +
> arch/arm/boot/dts/sunxi-h3-h5.dtsi | 10 +
> arch/arm64/boot/dts/allwinner/sun50i-a64.dtsi | 34 ++
> arch/arm64/boot/dts/allwinner/sun50i-h5.dtsi | 24 ++
> arch/arm64/boot/dts/allwinner/sun50i-h6.dtsi | 10 +
> drivers/clk/sunxi-ng/ccu-sun50i-a64.c | 3 +-
> drivers/clk/sunxi-ng/ccu-sun50i-h6-r.c | 2 +-
> drivers/clk/sunxi-ng/ccu-sun50i-h6.c | 3 +-
> drivers/clk/sunxi-ng/ccu-sun8i-a23.c | 3 +-
> drivers/clk/sunxi-ng/ccu-sun8i-a33.c | 3 +-
> drivers/clk/sunxi-ng/ccu-sun8i-a83t.c | 3 +-
> drivers/clk/sunxi-ng/ccu-sun8i-h3.c | 3 +-
> drivers/clk/sunxi-ng/ccu-sun8i-r.c | 2 +-
> drivers/clk/sunxi-ng/ccu-sun9i-a80.c | 3 +-
> drivers/firmware/Kconfig | 6 +
> drivers/firmware/Makefile | 1 +
> drivers/firmware/sunxi_msgbox_demo.c | 307 +++++++++++++++++
> drivers/mailbox/Kconfig | 10 +
> drivers/mailbox/Makefile | 2 +
> drivers/mailbox/sunxi-msgbox.c | 323 ++++++++++++++++++
> 22 files changed, 842 insertions(+), 9 deletions(-)
> create mode 100644 Documentation/devicetree/bindings/mailbox/allwinner,sunxi-msgbox.yaml
> create mode 100644 drivers/firmware/sunxi_msgbox_demo.c
> create mode 100644 drivers/mailbox/sunxi-msgbox.c
>
> --
> 2.21.0
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

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