MIPS: bootm.c: use debug macro to print debug message

The '## Transferring control ...' message is printed
only if DEBUG is enabled. Get rid of the 'ifdef DEBUG'
statement and use the debug macro instead.

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
MIPS: bootm.c: separate linux jump code

Move the actual jump code into a separate function.
This make the code reusable for bootm subcommands.

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Cc: Daniel Schwierzeck <daniel.schwierzeck@googlemail.com>
MIPS: bootm.c: separate environment initialization

Move the environment initialization code into a
separate function. This make the code reusable
for bootm subcommands.

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Cc: Daniel Schwierzeck <daniel.schwierzeck@googlemail.com>
MIPS: bootm.c: add support for 'prep' and 'go' subcommands

The bootm command supports subcommands since long time
however those subcommands are not yet usable on MIPS.

The patch is based on the ARM implementation, and it adds
support for the 'prep' and 'go' subcommands only.

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Cc: Daniel Schwierzeck <daniel.schwierzeck@googlemail.com>
MIPS: qemu-mips: fix a typo in README

The 'Limitations & comments' section refers to the
'-m mips' switch which is not valid. The '-m' switch
can be used for setting the virtual RAM size:

    $qemu-system-mips --help | grep '^-m '
    -m megs         set virtual RAM size to megs MB [default=128]
    $

The correct switch for specifying the machine type is '-M'.
Fix the text to refer to that.

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Cc: Daniel Schwierzeck <daniel.schwierzeck@googlemail.com>
Cc: Vlad Lungu <vlad.lungu@windriver.com>
MIPS: qemu-mips: add '-M mips' switch to the example usage command

Using the example command from the README file does
not work as expected. qemu shows a text similar to
the one below and it hangs.

    $ qemu-system-mips -L . -nographic
    Could not open option rom 'pxe-pcnet.rom': No such file or directory
    qemu-system-mips: pci_add_option_rom: failed to find romfile "vgabios-cirrus.bin"
    qemu: terminating on signal 15 from pid 19726

This happens because qemu emulates a Malta board by
default if the machine type is not defined explicitely
on the command line.

For a working test, the '-M mips' switch is required:

    $ qemu-system-mips -M mips -L . -nographic
    Could not open option rom 'vgabios.bin': No such file or directory

    U-Boot 2013.01-rc2-00132-g1e8e648-dirty (Jan 08 2013 - 09:06:42)

    Board: Qemu -M mips CPU: 24Kf proc_id=0x19300
    DRAM:  128 MiB
    ## Unknown flash on Bank 1 - Size = 0x00000000 = 0 MB
    Flash: 0 Bytes
    *** Warning - bad CRC, using default environment

    In:    serial
    Out:   serial
    Err:   serial
    Net:   NE2000
    Hit any key to stop autoboot:  0
    qemu-mips #

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Cc: Daniel Schwierzeck <daniel.schwierzeck@googlemail.com>
Cc: Vlad Lungu <vlad.lungu@windriver.com>
MIPS: qemu-mips: update and fix example usage in README

By now U-Boot supports Qemu MIPS for little and big endian
as well as 32 bit and 64 bit. Update and fix the example usage
in the README to reflect this.

Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
README.qemu-mips: move README file from board to doc directory

Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
README.mips: update known issues and TODOs

Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>