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Subject: Re: [PATCH v8 4/9] mfd: Add binding document for NVIDIA Tegra XUSB
From: Andrew Bresticker <abrestic@chromium.org>
To: Lee Jones <lee.jones@linaro.org>
Cc: Stephen Warren <swarren@wwwdotorg.org>,
        Thierry Reding <thierry.reding@gmail.com>,
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On Wed, May 13, 2015 at 9:50 AM, Lee Jones <lee.jones@linaro.org> wrote:
> On Wed, 13 May 2015, Andrew Bresticker wrote:
>
>> Lee,
>>
>> On Wed, May 13, 2015 at 7:39 AM, Lee Jones <lee.jones@linaro.org> wrote:
>> > On Mon, 04 May 2015, Andrew Bresticker wrote:
>> >
>> >> Add a binding document for the XUSB host complex on NVIDIA Tegra124
>> >> and later SoCs.  The XUSB host complex includes a mailbox for
>> >> communication with the XUSB micro-controller and an xHCI host-controller.
>> >>
>> >> Signed-off-by: Andrew Bresticker <abrestic@chromium.org>
>> >> Cc: Rob Herring <robh+dt@kernel.org>
>> >> Cc: Pawel Moll <pawel.moll@arm.com>
>> >> Cc: Mark Rutland <mark.rutland@arm.com>
>> >> Cc: Ian Campbell <ijc+devicetree@hellion.org.uk>
>> >> Cc: Kumar Gala <galak@codeaurora.org>
>> >> Cc: Samuel Ortiz <sameo@linux.intel.com>
>> >> Cc: Lee Jones <lee.jones@linaro.org>
>> >> ---
>> >> Changes from v7:
>> >>  - Move non-shared resources into child nodes.
>> >> New for v7.
>> >> ---
>> >>  .../bindings/mfd/nvidia,tegra124-xusb.txt          | 37 ++++++++++++++++++++++
>> >>  1 file changed, 37 insertions(+)
>> >>  create mode 100644 Documentation/devicetree/bindings/mfd/nvidia,tegra124-xusb.txt
>> >>
>> >> diff --git a/Documentation/devicetree/bindings/mfd/nvidia,tegra124-xusb.txt b/Documentation/devicetree/bindings/mfd/nvidia,tegra124-xusb.txt
>> >> new file mode 100644
>> >> index 0000000..bc50110
>> >> --- /dev/null
>> >> +++ b/Documentation/devicetree/bindings/mfd/nvidia,tegra124-xusb.txt
>> >> @@ -0,0 +1,37 @@
>> >> +NVIDIA Tegra XUSB host copmlex
>> >> +==============================
>> >> +
>> >> +The XUSB host complex on Tegra124 and later SoCs contains an xHCI host
>> >> +controller and a mailbox for communication with the XUSB micro-controller.
>> >> +
>> >> +Required properties:
>> >> +--------------------
>> >> + - compatible: For Tegra124, must contain "nvidia,tegra124-xusb".
>> >> +   Otherwise, must contain '"nvidia,<chip>-xusb", "nvidia,tegra124-xusb"'
>> >> +   where <chip> is tegra132.
>> >> + - reg: Must contain the base and length of the XUSB FPCI registers.
>> >> + - ranges: Bus address mapping for the XUSB block.  Can be empty since the
>> >> +   mapping is 1:1.
>> >> + - #address-cells: Must be 2.
>> >> + - #size-cells: Must be 2.
>> >> +
>> >> +Example:
>> >> +--------
>> >> +     usb@0,70098000 {
>> >> +             compatible = "nvidia,tegra124-xusb";
>> >> +             reg = <0x0 0x70098000 0x0 0x1000>;
>> >> +             ranges;
>> >> +
>> >> +             #address-cells = <2>;
>> >> +             #size-cells = <2>;
>> >> +
>> >> +             usb-host@0,70090000 {
>> >> +                     compatible = "nvidia,tegra124-xhci";
>> >> +                     ...
>> >> +             };
>> >> +
>> >> +             mailbox {
>> >> +                     compatible = "nvidia,tegra124-xusb-mbox";
>> >> +                     ...
>> >> +             };
>> >
>> > This doesn't appear to be a proper MFD.  I would have the USB and
>> > Mailbox devices probe seperately and use a phandle to point the USB
>> > device to its Mailbox.
>> >
>> > usb@xyz {
>> >         mboxes = <&xusb-mailbox, [chan]>;
>> > };
>>
>> Then what will set up the shared regmap?  The point of using an MFD
>> here was to share a register set with both the mailbox and xHCI
>> drivers and avoid having to map the same register set twice in two
>> separate drivers.
>
> Can you share the mapping please?

What do you mean?  That's what the MFD is doing now by setting up an
MMIO regmap to be shared between the two devices.

Thanks,
Andrew
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