blspec: Fix another crash with menu disabled ...

boot -l crashes with CONFIG_MENU disabled because blspec_alloc returns
with blspec->menu being NULL in this case. So guard the usage of
blspec->menu accordingly.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

boot command: Add timeout support for menu ...

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

boot command: make more flexible ...

With this we can do 'boot <name>' where name is one of:

 - a filename under /env/boot/
 - a full path to a boot script
 - a device name
 - a partition name under /dev/
 - a full path to a directory which
   - contains boot scripts, or
   - contains a loader/entries/ directory containing bootspec entries

Multiple names can be given, they are tried in order. So any mixture
between bootspec entries and bootscripts can be given. bootspec entries
can now also be given as a path to a directory containing bootspec entries.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

boot: Print boot entries in the order they are ...

Instead of first printing the traditional entries and the bootloader
spec entries afterwards.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

blspec: rename _hwdevice functions to _devicename ...

Since it's not necessarily the hardware device this seems to
be a more appropriate name.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

boot: remove incomplete 'title' handling in menu ...

The 'boot -m' command executes the /env/boot/* scripts in order to
determine the title of a boot menu entry. This is not complete and
depends on changes in the environment, so remove it for now.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Implement bootloader spec support for barebox ...

The Bootloader Specification describes a way how kernels can
be installed on devices and how they can be started by the bootloader.

The bootloader spec is currently supported by (x86) gummiboot and
by systemd which provides a kernel-install script. With the bootloader
spec it's possible for the Operating system to install a new kernel
without knowing about the bootloader and for the bootloader it's possible
to discover and start Operating Systems on a media without being
configured.

For more details about the spec see:

http://www.freedesktop.org/wiki/Specifications/BootLoaderSpec/

This patch adds barebox support for the spec. It enhances the 'boot'
command so that not only boot script names can be given, but also
devices containing bootloader spec entries. With this it's possible
to call the 'boot' command like: 'boot sd emmc net'. It would then
first look for bootloader spec entries on the (removable) sd card,
then, is nothing is found, on the internal emmc and if still
unsuccessful would call the 'net' bootscript.

The bootloader Spec currently doesn't specify which entry should be
default if multiple entries are found on a single device. Therefore
barebox currently has two extensions of the spec. The $BOOT diretory
can contain a file named 'default'. If present, the content of the
file is treated as a filename under $BOOT/loader/entries/ which is
used as default. Similarly if a file named 'once' is present, the
entry is started once and the file is removed afterwards. This is
useful for testing if a newly installed kernel works before making
it the default.

As on ARM and other Architectures a devicetree has to be specified
for the kernel, the 'devicetree' property is used to specify a
devicetree. Like 'kernel' and 'initrd' this also contains a pth
relative to $BOOT.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

bootm: Replace getenv_loadaddr with getenv_ul ...

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

defenv-2: replace boot script with command ...

This replaces the 'boot' script in the defaultenv-2 with a command
with the same behaviour. A command gives more flexibility for future
externsions

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>