doc: android: Convert to Sphinx format

Convert Android documentation from regular txt format to Sphinx (RST).
Also add Android index.rst file and reference it in root index.rst, so
that Android documentation is visible.

Test:

    $ make htmldocs
    $ xdg-open doc/output/index.html

Signed-off-by: Sam Protsenko <joe.skb7@gmail.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>

1 files changed, 173 insertions, 0 deletions

diff --git a/doc/android/fastboot-protocol.rst b/doc/android/fastboot-protocol.rst
new file mode 100644
index 0000000000..e723659e49
--- /dev/null
+++ b/doc/android/fastboot-protocol.rst
@@ -0,0 +1,173 @@
+.. SPDX-License-Identifier: GPL-2.0+
+
+FastBoot Version 0.4
+====================
+
+The fastboot protocol is a mechanism for communicating with bootloaders
+over USB.  It is designed to be very straightforward to implement, to
+allow it to be used across a wide range of devices and from hosts running
+Linux, Windows, or OSX.
+
+Basic Requirements
+------------------
+
+* Two bulk endpoints (in, out) are required
+* Max packet size must be 64 bytes for full-speed and 512 bytes for
+  high-speed USB
+* The protocol is entirely host-driven and synchronous (unlike the
+  multi-channel, bi-directional, asynchronous ADB protocol)
+
+
+Transport and Framing
+---------------------
+
+1. Host sends a command, which is an ascii string in a single
+   packet no greater than 64 bytes.
+
+2. Client response with a single packet no greater than 64 bytes.
+   The first four bytes of the response are "OKAY", "FAIL", "DATA",
+   or "INFO".  Additional bytes may contain an (ascii) informative
+   message.
+
+   a. INFO -> the remaining 60 bytes are an informative message
+      (providing progress or diagnostic messages).  They should
+      be displayed and then step #2 repeats
+
+   b. FAIL -> the requested command failed.  The remaining 60 bytes
+      of the response (if present) provide a textual failure message
+      to present to the user.  Stop.
+
+   c. OKAY -> the requested command completed successfully.  Go to #5
+
+   d. DATA -> the requested command is ready for the data phase.
+      A DATA response packet will be 12 bytes long, in the form of
+      DATA00000000 where the 8 digit hexidecimal number represents
+      the total data size to transfer.
+
+3. Data phase.  Depending on the command, the host or client will
+   send the indicated amount of data.  Short packets are always
+   acceptable and zero-length packets are ignored.  This phase continues
+   until the client has sent or received the number of bytes indicated
+   in the "DATA" response above.
+
+4. Client responds with a single packet no greater than 64 bytes.
+   The first four bytes of the response are "OKAY", "FAIL", or "INFO".
+   Similar to #2:
+
+   a. INFO -> display the remaining 60 bytes and return to #4
+
+   b. FAIL -> display the remaining 60 bytes (if present) as a failure
+      reason and consider the command failed.  Stop.
+
+   c. OKAY -> success.  Go to #5
+
+5. Success.  Stop.
+
+
+Example Session
+---------------
+
+.. code-block:: none
+
+    Host:    "getvar:version"        request version variable
+
+    Client:  "OKAY0.4"               return version "0.4"
+
+    Host:    "getvar:nonexistant"    request some undefined variable
+
+    Client:  "OKAY"                  return value ""
+
+    Host:    "download:00001234"     request to send 0x1234 bytes of data
+
+    Client:  "DATA00001234"          ready to accept data
+
+    Host:    < 0x1234 bytes >        send data
+
+    Client:  "OKAY"                  success
+
+    Host:    "flash:bootloader"      request to flash the data to the bootloader
+
+    Client:  "INFOerasing flash"     indicate status / progress
+             "INFOwriting flash"
+             "OKAY"                  indicate success
+
+    Host:    "powerdown"             send a command
+
+    Client:  "FAILunknown command"   indicate failure
+
+
+Command Reference
+-----------------
+
+* Command parameters are indicated by printf-style escape sequences.
+
+* Commands are ascii strings and sent without the quotes (which are
+  for illustration only here) and without a trailing 0 byte.
+
+* Commands that begin with a lowercase letter are reserved for this
+  specification.  OEM-specific commands should not begin with a
+  lowercase letter, to prevent incompatibilities with future specs.
+
+.. code-block:: none
+
+ "getvar:%s"           Read a config/version variable from the bootloader.
+                       The variable contents will be returned after the
+                       OKAY response.
+
+ "download:%08x"       Write data to memory which will be later used
+                       by "boot", "ramdisk", "flash", etc.  The client
+                       will reply with "DATA%08x" if it has enough
+                       space in RAM or "FAIL" if not.  The size of
+                       the download is remembered.
+
+  "verify:%08x"        Send a digital signature to verify the downloaded
+                       data.  Required if the bootloader is "secure"
+                       otherwise "flash" and "boot" will be ignored.
+
+  "flash:%s"           Write the previously downloaded image to the
+                       named partition (if possible).
+
+  "erase:%s"           Erase the indicated partition (clear to 0xFFs)
+
+  "boot"               The previously downloaded data is a boot.img
+                       and should be booted according to the normal
+                       procedure for a boot.img
+
+  "continue"           Continue booting as normal (if possible)
+
+  "reboot"             Reboot the device.
+
+  "reboot-bootloader"  Reboot back into the bootloader.
+                       Useful for upgrade processes that require upgrading
+                       the bootloader and then upgrading other partitions
+                       using the new bootloader.
+
+  "powerdown"          Power off the device.
+
+Client Variables
+----------------
+
+The ``getvar:%s`` command is used to read client variables which
+represent various information about the device and the software
+on it.
+
+The various currently defined names are::
+
+  version             Version of FastBoot protocol supported.
+                      It should be "0.3" for this document.
+
+  version-bootloader  Version string for the Bootloader.
+
+  version-baseband    Version string of the Baseband Software
+
+  product             Name of the product
+
+  serialno            Product serial number
+
+  secure              If the value is "yes", this is a secure
+                      bootloader requiring a signature before
+                      it will install or boot images.
+
+Names starting with a lowercase character are reserved by this
+specification.  OEM-specific names should not start with lowercase
+characters.