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.
Cc: Jim Lin <jilin@nvidia.com>
Cc: Stefan Agner <stefan@agner.ch>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
2 files changed