On Thu, 14 May 2015, Jon Hunter wrote:

Hi Lee,

On 13/05/15 15:39, Lee Jones wrote:

quoted

On Mon, 04 May 2015, Andrew Bresticker wrote:

quoted

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 <redacted>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Pawel Moll <redacted>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Ian Campbell <redacted>
Cc: Kumar Gala <redacted>
Cc: Samuel Ortiz <redacted>
Cc: Lee Jones <redacted>
---
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 at 0,70098000 {
+		compatible = "nvidia,tegra124-xusb";
+		reg = <0x0 0x70098000 0x0 0x1000>;
+		ranges;
+
+		#address-cells = <2>;
+		#size-cells = <2>;
+
+		usb-host at 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 at xyz {
	mboxes = <&xusb-mailbox, [chan]>;
};

I am assuming that Andrew had laid it out like this to reflect the hw
structure. The mailbox and xhci controller are part of the xusb
sub-system and hence appear as child nodes. My understanding is that for
device-tree we want the device-tree structure to reflect the actual hw.
Is this not the case?

Yes, the DT files should reflect h/w.  I have requested to see what
the memory map looks like, so I might provide a more appropriate
solution to accepting a pretty pointless MFD.

Two solutions spring to mind.  You can either call
of_platform_populate() from the USB driver, as some already do:

  drivers/usb/dwc3/dwc3-exynos.c:
    ret = of_platform_populate(node, NULL, NULL, dev);
  drivers/usb/dwc3/dwc3-keystone.c:
    error = of_platform_populate(node, NULL, NULL, dev);
  drivers/usb/dwc3/dwc3-omap.c:
    ret = of_platform_populate(node, NULL, NULL, dev);
  drivers/usb/dwc3/dwc3-qcom.c:
    ret = of_platform_populate(node, NULL, NULL, qdwc->dev);
  drivers/usb/dwc3/dwc3-st.c:
    ret = of_platform_populate(node, NULL, NULL, dev);
  drivers/usb/musb/musb_am335x.c:
    ret = of_platform_populate(pdev->dev.of_node, NULL, NULL, &pdev->dev);

Or use the "simple-mfd", which is currently in -next:

  git show next/master:Documentation/devicetree/bindings/mfd/mfd.txt

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org ? Open source software for ARM SoCs
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