There is a new feature in loadtools (fc-loadtool & friends) and rvinterf as of
fc-host-tools-r12, actually functional as of fc-host-tools-r14: target boot
control.  In a typical development environment where FC host tools run on a
general-purpose PC or laptop and communicate with various Calypso targets via
general-purpose serial or USB-serial ports, adapters and cables, there is
generally no way for the host computer running FC host tools to directly command
the Calypso target to power on and/or reboot - instead such control must be
performed "out of band" by the operator pressing the PWON or RESET button on
the target device; some targets may even require complex battery manipulations.
However, there may be more elaborate (less casual) setups where FC host tools
run on a special kind of host system which does have some means to directly
control power and reset to an associated Calypso target:

* Our new FreeCalypso DUART28 adapter available as of 2020-09 has an optional
  provision (requires additional wire connections and a custom patch to Linux
  kernel ftdi_sio driver) for controlling Calypso target board PWON and RESET
  with otherwise unused secondary channel RTS and DTR outputs - see the new
  DUART28-boot-control article for the details.

* The Mother has a plan to produce another custom FT2232D-based adapter called
  FC-UJA, standing for FreeCalypso UART+JTAG Adapter.  This FC-UJA will be a
  special FT2232D adapter whose Channel A will operate in MPSSE mode, connecting
  to the Calypso target's JTAG and nTESTRESET signals, whereas Channel B will
  act as a standard UART, i.e., a ttyUSB device.  This FC-UJA needs to be built
  as a prerequisite before embarking on the ambitious HSMBP (Handset Motherboard
  Prototype) project, as the special adapter will be required for working with
  the HSMBP in development.  When FC-UJA becomes a reality, FC host tools
  running on a development host with this adapter will need to be given the
  ability to issue nTESTRESET pulses to the target through the adapter's
  MPSSE+GPIO channel; this nTESTRESET pulse will cause the Calypso target to
  deep-reset, power on and boot.

* FC host tools (particularly fc-loadtool) may run on the application processor
  of a smartphone such as Openmoko GTA02.  In such environments the AP will have
  special ad hoc control signals (typically GPIOs) to the modem, at the minimum
  controlling the modem's PWON line.  OM GTA02 added an overriding control of
  overall power to the modem; other designs may reasonably add control of the
  modem's RESET line.

* There may be special commercial applications in which one or more Calypso
  modems are subservient to a control processor that acts similarly to the AP
  of a smartphone, with that control processor not only communicating with its
  slave modems via UARTs, but also controlling their power and reset.

Where does the desire for target boot control in loadtools and rvinterf come
from?  Consider the conventional usage model where no target boot control
exists: you first run fc-loadtool or fc-iram or fc-xram or rvinterf on your
target /dev/ttyXXX, then press the PWON or RESET button on the target.  Now
suppose that the finger-actuated button has been replaced with some magic
command that can be executed on the host system to produce the same effect -
now what?  If the usage model stays the same, then you have to first run your
fc-loadtool or fc-iram or fc-xram or rvinterf command same as before, then as
it sits there waiting for the target to boot, you have to open another terminal
window, get another ssh session into the system or whatever, and run the magic
command that replaces the manual button press.  Very cumbersome, hence the
desire for a better way.

Support for target boot control in FC host tools consists of a new -P option
implemented in all of loadtools programs and in rvinterf, as well as a special
configuration file which needs to be manually created if external boot control
commands are to be used.  There are two target boot control models, built-in
and external:

* Built-in target boot control integrated into FC host tools themselves is
  currently available only for the DTR/RTS pulsing method implemented on our
  DUART28 adapter: -Pdtr means pulse DTR and -Prts means pulse RTS.  Please
  refer to the DUART28-boot-control article for the details.

* In the other case of external boot control commands, there exist one or more
  "magic commands": a magic command is any shell command (anything that can be
  passed to /bin/sh -c) whose execution causes a connected Calypso target device
  to power on and boot.  Naturally these commands will be very specific to your
  custom system; they are NOT part of FC host tools!

* These magic commands may be long, and requiring the user to include each magic
  command in full on fc-loadtool, rvinterf etc invokation lines is undesirable.
  To save typing, we associate a short name (which you choose yourself as you
  see fit) with each magic command, and we have a configuration file (which you
  need to create) that defines the mapping.

* The argument to the new -P option is the short name to be looked up in the
  configuration file.  (Built-in boot control names 'dtr' and 'rts' are reserved
  and cannot be used for external boot control commands.)

The configuration file needs to be created in /opt/freecalypso/bootctrl.conf;
let us illustrate it with some examples.

Example 1: FC-UJA
=================

When FC-UJA becomes a reality, there will be a program called fc-testreset that
will locate the attached FC-UJA by its USB ID, connect to FT2232D Channel A and
generate the desired reset pulse on its output.  The configuration in
/opt/freecalypso/bootctrl.conf may look as follows:

uja	fc-testreset

This configuration associates boot control name 'uja' with shell command
fc-testreset.  A developer would then run fc-loadtool like this:

fc-loadtool -h fcfam -Puja /dev/ttyUSB0

if ttyUSB0 is where FC-UJA's UART channel ended up.  fc-loadtool would run
normally, sending beacons to /dev/ttyUSB0 and waiting for a Calypso boot ROM
response, but it would also execute the fc-testreset command listed in the
configuration file, and if everything is connected correctly, the resulting
nTESTRESET pulse will cause the target to boot.

The possibility of a single host talking to multiple Calypso targets is fully
supported: if you have multiple FC-UJA adapters with different USB descriptor
serial numbers programmed in their EEPROMs connected to respective Calypso
targets, you could have a /opt/freecalypso/bootctrl.conf setup like this:

uja1	fc-testreset -d serial1
uja2	fc-testreset -d serial2

and then run fc-loadtool accordingly:

fc-loadtool -h fcfam -Puja1 /dev/ttyUSB3
fc-loadtool -h fcfam -Puja2 /dev/ttyUSB4

Example 2: Openmoko GTA02
=========================

There is a modem-power-ctrl.sh script provided in the openmoko directory of this
FC host tools package; if you are going to run fc-loadtool on the application
processor of your GTA02 smartphone, you should install this script in some
sensible location such as /usr/local/sbin/modem-power-ctrl.  Then fill in your
/opt/freecalypso/bootctrl.conf file as follows:

lm	/usr/local/sbin/modem-power-ctrl boot

The name 'lm' stands for "local modem"; you can then run fc-loadtool as follows:

fc-loadtool -h fic -Plm /dev/ttySAC0

Change from the past
====================

Back in 2013 the predecessor to our current FC host tools package was just
loadtools, and we had a special configuration for building our loadtools to run
on the GTA02 AP.  But it worked backwards relative to our current arrangement:
the current sensible arrangement is that a tool like fc-loadtool run without
any special options simply operates on the specified serial port without any
special magic, and if special magic is desired, it needs to be requested
explicitly with the new -P option; the old loadtools-on-GTA02-AP arrangement
was the opposite: you needed to specify -n to get "regular" operation, otherwise
the tools would automatically operate the modem power control.

Now that we support many more different Calypso hardware targets than we even
knew about in 2013-2014, a cleanup has been long overdue.  The new arrangement
as of fc-host-tools-r12 cleans up the mess in several ways:

* Our FC host tools package has grown so much that making special code
  configurations for special environments like the AP of some particular
  smartphone is no longer scalable; now we just have one standard FC host tools
  package without platform-specific hacks.

* Openmoko platform was certainly very special to us once, but it is not so
  special any more - now we just treat it the same as any other.  Our target
  boot control mechanism has now been generalized from just OM GTA02 to any
  arbitrary platform with similar needs.

* No more reversal of the standard tool paradigm: we have standard operation by
  default, magic on request with an option.