ARM: rpi_b: set $fdtfile in default environment

U-Boot names the Raspberry Pi board rpi_b. This means that the common
expression for DTB filename ${soc}-${board}.dtb expands to
bcm2835-rpi_b.dtb. However, the DTB generated by the Linux kernel is
bcm2835-rpi-b.dtb. Set $fdtfile in U-Boot's environment so that scripts
look for the correct DTB filename.

An alternative would be to rename the U-Boot board to rpi-b. However,
that change would be far more invasive, and end up affecting users (i.e
they'd have to change their U-Boot build commands).

Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
ARM: bcm2835: config.mk isn't needed

The entries in config.mk were needed so that U-Boot could be built
with an old version of the Raspberry Pi Foundation's toolchain. Without
them, the build would error out with:

...-ld: error: .../libgcc.a(_bswapsi2.o) uses VFP register arguments,
u-boot does not

However, none of the 3 toolchains in the latest version of their
tools.git, nor the Ubuntu/Linaro ARM compilers in at least Ubuntu Quantal
or Saucy, need these options set in order to compile a working U-Boot.
Hence, remove the options for simplicity.

Reported-by: Tom Rini <trini@ti.com>
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
pxe: allow compilation when !defined(CONFIG_CMD_NET)

pxe.c provides both the "pxe" command which relies on a network, and the
"sysboot" command which doesn't. Fix the file to compile when network
support isn't enabled. This is useful e.g. on the Raspberry Pi which has
no network support yet, but will soon support the sysboot command.

Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
---
This patch doesn't appear to depend on anything much, but is needed by
the rest of this series. Given the dependencies in the rest of this
series, either (a) this one patch can be applied to u-boot/master, and
then u-boot/arm can merge that in before the rest of the series, or (b)
u-boot/master can be merged into u-boot-arm/master, then this whole
series applied there.
ARM: rpi_b: convert to use distro defaults

Modify the rpi_b board to include the "distro defaults" header, so that
all the config options distros expect are enabled. Remove any #defines
that enable the same options from the rpi_b.h.

Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
---
Patches 2/4 and 4/4 depend on various patches in u-boot/master, so that
will need to be merged into u-boot-arm/master if this series gets applied
there. In particular, "config: add config_distro_defaults.h" and various
patches before that are required.
ARM: rpi_b: load /uEnv.txt from MMC at startup

The Pi has no flash to store an environment in the usual fashion. However,
the user may wish to customize the environment. We know that the SD card
must be present, since that's where the boot ROM has loaded U-Boot from.
So, load uEnv.txt from there early during boot. This allows the user to
e.g. customize boot_targets, in order to automatically select network
boot.

Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
ARM: rpi_b: rework boot scripts, enable sysboot

Rework rpi_b's bootcmd (and sub-commands) to match Tegra's bootcmd as
much as possible. This will aid in a future patch which will create a
common header e.g. config_distro_bootcmd.h.

While at it, enable booting from extlinux.conf using the sysboot command.

The iteration and componentization currently makes a little more sense
for Tegra than RPi, but I'd still like to keep the two as similar as
possible. USB and networking support is coming to the RPi in due course,
and it'll all make more sense then anyway.

Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
DWC2: add host driver from Oleksandr's branch

swarren changelog:
* Fixed prototype of usb_lowlevel_init() to match upstream change.

TODO:
* Rename dwc -> dwc2

Signed-off-by: Oleksandr Tymoshenko <gonzo@bluezbox.com>
Signed-off-by: Stephen Warren <swarren@wwdotorg.org>
DWC2: fix unused variables

TODO: Squash into previous commit.

Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
DWC2: rename from DWC

TODO: Squash into previous commit.

Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
ARM: rpi_b: enable USB features in config

* Enable USB HW driver
* Don't disable USB-related commands any more
* Add USB-related support to bootcmd

Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
HACK: SMSC95XX: hard-code Ethernet address

TODO: get this from firmware instead

Signed-off-by: Oleksandr Tymoshenko <gonzo@bluezbox.com>
[swarren: extracted from a larger patch]
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>