Point mailbox daemon documentation to mboxbridge

Simlar to the update to mbox_protocol.md, those looking for the
documentation on the mailbox daemon should refer to the more
up-to-date version in the openbmc/mboxbridge repository.

Change-Id: Iedea144ee70c9c4059f08ccb131ddc4ecec7ad36
Signed-off-by: Brandon Wyman <bjwyman@gmail.com>

1 files changed, 2 insertions, 180 deletions

diff --git a/Documentation/mboxd.md b/Documentation/mboxd.md
index d60925d..acbb174 100644
--- a/Documentation/mboxd.md
+++ b/Documentation/mboxd.md
@@ -1,181 +1,3 @@
-Copyright 2017 IBM
+Please reference the canonical mbox protocol documentation:
 
-Licensed under the Apache License, Version 2.0 (the "License");
-you may not use this file except in compliance with the License.
-You may obtain a copy of the License at
-
-  http://www.apache.org/licenses/LICENSE-2.0
-
-Unless required by applicable law or agreed to in writing, software
-distributed under the License is distributed on an "AS IS" BASIS,
-WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-See the License for the specific language governing permissions and
-limitations under the License.
-
-## Intro
-
-This document describes the reference mailbox daemon contained in this
-repository.
-
-## Files
-
-The main mailbox daemon is implemented in mboxd.c. This file uses helper
-functions from the various mboxd_*.c files.
-
-```
-mboxd_dbus.c -    Contains the handlers for the dbus commands which the daemon can
-                  receive.
-mboxd_flash.c -   Contains the functions for performing flash access including
-                  read, write and erase.
-mboxd_lpc.c -     Contains the functions for controlling the lpc bus mapping
-                  including pointing the bus so it maps flash and memory.
-mboxd_msg.c -     Contains the handlers for the mbox commands which the daemon
-                  can receive.
-mboxd_windows.c - Contains the functions for managing the window cache.
-```
-
-## Daemon State
-
-The daemon is a state machine with 5 valid states:
-
-```
-UNINITIALISED -         The daemon is still in the initialisation phase and
-                        will not respond
-ACTIVE_MAPS_FLASH -     The daemon is polling for incoming commands, is not
-                        currently suspended and the lpc bus maps the flash
-                        device.
-SUSPEND_MAPS_FLASH -    The daemon is polling for incoming commands, is
-                        currently suspended and the lpc bus maps the flash
-                        device.
-ACTIVE_MAPS_MEM -       The daemon is polling for incoming commands, is not
-                        currently suspended and the lpc bus maps the reserved
-                        memory region.
-SUSPEND_MAPS_MEM -      The daemon is polling for incoming commands, is
-                        currently suspended and the lpc bus maps the reserved
-                        memory region.
-```
-
-As described in the protocol, the daemon can be suspended to allow the BMC to
-access flash without the daemon interfering. The daemon will still respond to
-commands while suspended but won't allow the host to, or itself, access the
-flash.
-
-### State Transitions
-
-```
-UNINITIALISED -> ACTIVE_MAPS_FLASH -      Uninitiated: Occurs when the daemon is
-                                          finished initialising.
-ACTIVE_MAPS_FLASH -> SUSPEND_MAPS_FLASH - Suspend command received over
-                                          dbus
-SUSPEND_MAPS_FLASH -> ACTIVE_MAPS_FLASH - Resume command received over
-                                          dbus
-ACTIVE_MAPS_MEM -> SUSPEND_MAPS_MEM -     Suspend command received over dbus
-SUSPEND_MAPS_MEM -> ACTIVE_MAPS_MEM -     Resume command received over dbus
-ACTIVE_MAPS_FLASH -> ACTIVE_MAPS_MEM -    GET_MBOX_INFO command received
-SUSPEND_MAPS_FLASH -> SUSPEND_MAPS_MEM -  GET_MBOX_INFO command received
-ACTIVE_MAPS_MEM -> ACTIVE_MAPS_FLASH -    Reset dbus or mbox command received
-SUSPEND_MAPS_MEM -> SUSPEND_MAPS_FLASH -  Transition not allowed, we
-                                          don't let the host modify flash
-                                          while the daemon is suspended.
-```
-
-## Window Cache
-
-While the protocol describes that there is only one active window at a time,
-the daemon keeps a cache of previously accessed windows to avoid the need to
-reload them from flash should the host access them again in the future.
-
-The reserved memory region is divided among a number of windows which make up
-the window cache. When the host requests a flash offset the cache is searched
-for one which contains that offset. If one is found we simply point the host to
-it at the correct lpc offset for that windows location and the requested flash
-offset.
-
-If there is no window in the cache which contains the requested flash offset
-then we have to find one to load with the requested flash contents. If there
-are any windows which are empty then we choose those, otherwise we choose one to
-evict using a least recently used (LRU) scheme. The flash is then copied into
-this window and the host pointed at its location on the lpc bus.
-
-When ever the flash is changed we have to invalidate all windows in the window
-cache as their contents may no longer accurately reflect those of the flash.
-
-## Daemon Operation
-
-### Invocation
-
-The daemon is invoked on the command line with a few parameters:
-
-```
-(*) - required
-(#) - optional but recommended
-(~) - optional
-
---flash *       - The size of the PNOR image on the flash device
---window-size # - The size to make each window in the cache
---window-num #  - The number of windows to have in the cache
---verbose ~     - Increase the verbosity with which the daemon runs
---sys-log ~     - Use the system log rather than outputing to the console
-```
-
-If any of the required parameters are missing or invalid an error will be
-printed and the daemon will terminate.
-If window-size and window-num aren't specified then the default is to have a
-single window which spans the entire reserved memory region.
-
-### Initialisation
-
-After the command line has been parsed the daemon will initalise its various
-interfaces. If any of these initialisations fail it will print an error and the
-daemon will terminate.
-
-After initilisation the daemon points the lpc mapping to the actual flash
-device, sets the BMC_READY BMC event and starts polling.
-
-### Polling
-
-The daemon sits in a poll loop waiting for an event to happen on one or more of
-the mbox, dbus or signal file descriptors.
-
-#### Handling MBOX Commands
-
-When an event occurs on the mbox file descriptor the mbox request is read from
-the mbox registers and processed.
-
-The command is validated and then the appropriate handler called. The response
-is then written back to the mbox registers to indicate the outcome of the
-command and an interrupt generated to the host.
-
-#### Handling DBUS Commands
-
-When an event occurs on the dbus file descriptor the dbus request is read from
-the dbus interface and processed.
-
-The command is validated and then the appropriate handler called. The response
-is then written back to the dbus interface to indicate the outcome of the
-command.
-
-#### Handling Signals
-
-The daemon blocks SIGINTs, SIGTERMs, and SIGHUPs and instead polls for them on
-a signal file descriptor.
-
-When an event occurs on this file descriptor the signal received is determined
-and processed as follows:
-
-```
-SIGINT -  Terminate the daemon
-SIGTERM - Terminate the daemon
-SIGHUP -  Clear the window cache and point the lpc bus mapping back to
-          flash
-```
-
-### Termination
-
-The daemon can be terminated for multiple reasons; invalid command line, unable
-to initialise, received SIGINT or SIGTERM, or because it received the kill dbus
-command.
-
-On termination the daemon clears the window cache and notifys the host that the
-active window has been closed, points the lpc bus mapping back to flash, clears
-the BMC_READY BMC event bit and frees all of its allocated resources.
+    https://github.com/openbmc/mboxbridge/blob/master/Documentation/mboxd.md