usb: tegra: fix PHY selection code

The TRM for Tegra30 and later all state that USBMODE_CM_HC must be set
before writing to hostpc1_devlc to select which PHY to use for a USB
controller. However, neither init_{utmi,ulpi}_usb_controller() do this
today, so the register writes they perform for PHY selection do not
work.

For the UTMI case, this was hacked around in commit 7e44d9320ed4 "ARM:
Tegra: USB: EHCI: Add support for Tegra30/Tegra114" by adding code to
ehci_hcd_init() which sets USBMODE_CM_HC and duplicates the PHY
selection register write. This code doesn't cover the ULPI case, so I
wouldn't be surprised if ULPI doesn't work with the current code, unless
the ordering requirement only ends up being an issue in HW for UTMI not
ULPI.

This patch fixes init_{utmi,ulpi}_usb_controller() to correctly set
USBMODE_CM_HC before selecting the PHY. Now that this works, we can
remove the duplicate UTMI-specific code in ehci_hcd_init(), thus
simplifying that function.

Cc: Jim Lin <jilin@nvidia.com>
Cc: Stefan Agner <stefan@agner.ch>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
usb: tegra: refactor PHY type selection

Both init_{utmi,ulpi}_usb_controller() have nearly identical code for
PHY type selection. Pull this out into a common function to remove the
duplication.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
usb: tegra: support device mode

A few changes are made to the Tegra EHCI driver so that it can set
everything up for device-mode operation on the first USB controller.
This can be used in conjunction with ci_udc.c to operate as a USB
device.

Detailed changes are:

* Rename set_host_mode() to set_up_vbus() since that's really what it
  does.

* Modify set_up_vbus() to know whether it's initializing in host or
  device mode, and:

  - Skip the external VBUS check in device mode, since external VBUS is
    expected in this case.

  - Disable VBUS output in device mode.

* Modify init_phy_mux() to know whether it's initializing in host or
  device mode, and hence skip setting USBMODE_CM_HC (which enables host
  mode) in device mode. See the comments in that function for why this
  is safe w.r.t. the ordering requirements of PHY selection.

* Modify init_utmi_usb_controller() to force "b session valid" in device
  mode, since the HW requires this. This is done in UTMI-specific code,
  since we only support device mode on the first USB controller, and that
  controller can only talk to a UTMI PHY.

* Enhance ehci_hcd_init() to error-check the requested host-/device-mode
  vs. the dr_mode (dual-role mode) value present in device tree, and the
  HW configurations which support device mode.

* Enhance ehci_hcd_init() not to skip HW initialization when switching
  between host and device mode on a controller. This requires remembering
  which mode the last initialization used.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
USB Mass Storage hacks for Venice2