The qcom HSIC ULPI phy doesn't have any bits set in the vendor or
product ID registers. This makes it impossible to make a ULPI
driver match against the ID registers. Add support to discover
the ULPI phys via DT/device properties to help alleviate this
problem. In the DT case, we'll look for a ULPI bus node
underneath the device registering the ULPI viewport (or the
parent of that device to support chipidea's device layout) and
then match up the phy node underneath that with the ULPI device
that's created.

The side benefit of this is that we can use standard properties
in the phy node like clks, regulators, gpios, etc. because we
don't have firmware like ACPI to turn these things on for us. And
we can use the DT phy binding to point our phy consumer to the
phy provider.

Furthermore, this avoids any problems with reading the ID
registers before the phy is powered up. The ULPI bus supports
native enumeration by reading the vendor ID and product ID
registers at device creation time, but we can't be certain that
those register reads will succeed if the phy is not powered.

If the ULPI spec had some generic power sequencing for these
registers we could put that into the ULPI bus layer and power up
the device before reading the ID registers. Unfortunately this
doesn't exist and the power sequence is usually device specific.
By having the vendor and product ID properties in ACPI or DT, we
can match up devices with drivers without having to read the
hardware before it's powered up and avoid this problem.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Cc: <redacted>
Cc: Rob Herring <robh+dt@kernel.org>
Signed-off-by: Stephen Boyd <redacted>
---
 Documentation/devicetree/bindings/usb/ulpi.txt | 35 ++++++++++++
 drivers/usb/common/ulpi.c                      | 74 +++++++++++++++++++++++++-
 2 files changed, 107 insertions(+), 2 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/usb/ulpi.txt

diff --git a/Documentation/devicetree/bindings/usb/ulpi.txt b/Documentation/devicetree/bindings/usb/ulpi.txt
new file mode 100644
index 000000000000..c649ca5b0996
--- /dev/null
+++ b/Documentation/devicetree/bindings/usb/ulpi.txt

@@ -0,0 +1,35 @@
+ULPI bus binding
+----------------
+
+Phys that are behind a ULPI connection can be described with the following
+binding. The host controller shall have a "ulpi" named node as a child, and
+that node shall have one enabled node underneath it representing the ulpi
+device on the bus.
+
+PROPERTIES
+----------
+
+- ulpi-vendor:
+    Usage: optional
+    Value type: <u16>
+    Definition: The USB-IF assigned vendor id for this device
+
+- ulpi-product:
+    Usage: required if ulpi-vendor is present
+    Value type: <u16>
+    Definition: The vendor assigned product id for this device
+
+EXAMPLE
+-------
+
+usb {
+	compatible = "vendor,usb-controller";
+
+	ulpi {
+		phy {
+			compatible = "vendor,phy";
+			ulpi-vendor = /bits/ 16 <0x1d6b>;
+			ulpi-product = /bits/ 16 <0x0002>;
+		};
+	};