usb: ci_udc: pre-allocate ep0 req

Allocate ep0's USB request object when the UDC driver is probed. This
solves a couple of issues in the current code:

a) A request object always exists for ep0. Prior to this patch, if setup
transactions arrived in an unexpected order, handle_setup() would need
to reply to a setup transaction before any ep0 usb_req was created.

This issue was introduced in commit 2813006fecda "usb: ci_udc: allow
multiple buffer allocs per ep."

b) handle_ep_complete no longer /has/ to queue the ep0 request again
after every single request completion. This is currently required, since
handle_setup() assumes it can find some request object in ep0's request
queue. This patch doesn't actually stop handle_ep_complete() from always
requeueing the request, but the next patch will.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
usb: ci_udc: complete ep0 direction handling

handle_setup() currently assumes that the response to a Setup transaction
will be an OUT transaction, and any subsequent packet (if any) will be an
IN transaction. This appears to be valid in many cases; both USB
enumeration and Mass Storage work OK with this restriction. However, DFU
uses ep0 to transfer data in both directions. This renders the assumption
invalid; when sending data from device to host, the Data Stage is an IN
transaction, and the Status Stage is an OUT transaction. Enhance
handle_setup() to deduce the correct direction for the USB transactions
based on Setup transaction data.

ep0's request object only needs to be automatically re-queued when the
Data Stage completes, in order to implement the Status Stage. Once the
Status Stage transaction is complete, there is no need to re-queue the
USB request, so don't do that.

Don't sent USB request completion callbacks for Status Stage transactions.
These were queued by ci_udc itself, and only serve to confuse the USB
function code. For example, f_dfu attempts to interpret the 0-length data
buffers for Status Stage transactions as DFU packets. These buffers
contain stale data from the previous transaction. This causes f_dfu to
complain about a sequence number mismatch.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
dfu: fix some issues with reads/uploads

FIXME: This breaks filesystem DFU, since I've only implemented the
changes for raw device DFU.

DFU read support appears to rely upon dfu->read_medium() updating the
passed-by-reference len parameter to indicate the remaining size
available for reading.

dfu_read_medium_mmc() never does this, and the implementation of
dfu_read_medium_nand() will only work if called just once; it hard-codes
the value to the total size of the NAND device irrespective of read
offset.

I believe that overloading dfu->read_medium() is confusing. As such,
this patch introduces a new function dfu->get_medium_size() which can
be used to explicitly find out the medium size, and nothing else.
dfu_read() is modified to use this function to set the initial value for
dfu->r_left, rather than attempting to use the side-effects of
dfu->read_medium() for this purpose.

Due to this change, dfu_read() must initially set dfu->b_left to 0, since
no data has been read.

dfu_read_buffer_fill() must also be modified not to adjust dfu->r_left
when simply copying data from dfu->i_buf_start to the upload request
buffer. r_left represents the amount of data left to be read from HW.
That value is not affected by the memcpy(), but only by calls to
dfu->read_medium().

After this change, I can read from either a 4MB or 1.5MB chunk of a 4MB
eMMC boot partion with CONFIG_SYS_DFU_DATA_BUF_SIZE==1MB. Without this
change, attempting to do that would result in DFU read returning no data
at all due to r_left never being set.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
ARM: tegra: enable USB device mode and UMS on some boards

For each of Jetson TK1, Venice2, and Beaver:

- Enable the first USB controller in DT, and describe its configuration.

- Enable USB device/gadge support. This allows the user to type e.g.
  "ums 0 mmc 0" at the command-line to cause U-Boot to act a USB device
  implementing the USB Mass Storage protocol, and expose MMC device 0
  that way.

This allows a host PC to mount the Tegra device's MMC, partition it, and
install a filesystem on it.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
---
v2: Add missing tegra-common-ums.h

Note: This depends on a bunch of changes to the Tegra EHCI driver and
U-Boot UMS (USB Mass Storage) code, which are likely to be taken through
the USB maintainer tree. We should hold off until those commits show up
in the main U-Boot repo before applying this patch.

FIXME: I need to allocat a valid CONFIG_G_DNL_PRODUCT_NUM.
HACK: ARM: tegra: enable DFU too

FIXME: This should likely be in a separate tegra-common-dfu.h.

Signed-off-by: Stephen Warren <swarren@nvidia.com>