Permit to select a bootmenu entry with a key shortcut. This is
especially useful in production or testing scenario to automate flashing
procedure or testing procedure.

The boot entry are changed to append the shortcut key to it.

Example:
      1. Run default boot command.
      2. Boot system via TFTP.
      3. Boot production system from NAND.
      4. Boot recovery system from NAND.
      5. Load production system via TFTP then write to NAND.
      6. Load recovery system via TFTP then write to NAND.
      7. Load BL31+U-Boot FIP via TFTP then write to NAND.
      8. Load BL2 preloader via TFTP then write to NAND.
      9. Reboot.
      a. Reset all settings to factory defaults.
      0. Exit

0 is always reserved for Exit to console.
On pressing the keyboard key 2, the bootmenu entry 2 is selected and
executed.

Up to 34 key shortcut (0 excluded as reserved) are supported from 1-9
and a-z.
If a shortcut key not present in the bootmenu list is pressed, it is
simply ignored and eventually the autoboot is interrupted.

Capital A-Z are converted to lower a-z and the related option is
selected.

Suggested-by: Weijie Gao <weijie.gao@mediatek.com>
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Tested-by: Petr Štetiar <ynezz@true.cz>

Create a init function so that it is easy to use command-line reading.

Signed-off-by: Simon Glass <sjg@chromium.org>

When inputting text outside the command line we don't want to use tab
for command completion. Add an option to control this.

Signed-off-by: Simon Glass <sjg@chromium.org>

When inputting text outside the command line we don't want history to be
accessible. Add an option to control this.

Signed-off-by: Simon Glass <sjg@chromium.org>

Move most of the inner loop from cread_line() into a new function. This
will allow using it from other code.

This involves adding a few more members to the state struct.

Signed-off-by: Simon Glass <sjg@chromium.org>

We want to reuse the editing code elsewhere. As a first step, move the
common variables into a struct. This will allow us to eventually put the
contents of the inner loop in a function, so it can be called from
elsewhere.

Signed-off-by: Simon Glass <sjg@chromium.org>

There is a function for this but it is never used. Showing the history is
a useful feature, so add a new 'history' command.

Signed-off-by: Simon Glass <sjg@chromium.org>

The second call to cli_ch_process() is in the wrong place, meaning that
the one of the characters of an invalid escape sequence is swallowed
instead of being returned.

Fix the bug and add a test to cover this.

This behaviour matches that of the code before cli_getch() was
introduced. This was verified on the commit before b08e9d4b66 i.e.:

   7d850f85aad ("sandbox: Enable mmc command and legacy images")

Signed-off-by: Simon Glass <sjg@chromium.org>
Reported-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

Avoid duplicating some of the escape-sequence processing here and use the
CLI function instead.

Signed-off-by: Simon Glass <sjg@chromium.org>

The current cread_line() function is very long. It handles the escape
processing inline. The menu command does similar processing but at the
character level, so there is some duplication.

Split the character processing into a new function cli_ch_process() which
processes individual characters and returns the resulting input character,
taking account of escape sequences. It requires the caller to set up and
maintain its state.

Update cread_line() to use this new function.

The only intended functional change is that an invalid escape sequence
does not add invalid/control characters into the input buffer, but instead
discards these.

Signed-off-by: Simon Glass <sjg@chromium.org>