/*

   * Copyright (c) 2014 The Chromium OS Authors.

   *

   * SPDX-License-Identifier:	GPL-2.0+

   */
  
  Native Execution of U-Boot
  ==========================
  
  The 'sandbox' architecture is designed to allow U-Boot to run under Linux on
  almost any hardware. To achieve this it builds U-Boot (so far as possible)
  as a normal C application with a main() and normal C libraries.
  
  All of U-Boot's architecture-specific code therefore cannot be built as part
  of the sandbox U-Boot. The purpose of running U-Boot under Linux is to test
  all the generic code, not specific to any one architecture. The idea is to
  create unit tests which we can run to test this upper level code.
  
  CONFIG_SANDBOX is defined when building a native board.

  The board name is 'sandbox' but the vendor name is unset, so there is a
  single board in board/sandbox.

  
  CONFIG_SANDBOX_BIG_ENDIAN should be defined when running on big-endian
  machines.

  There are two versions of the sandbox: One using 32-bit-wide integers, and one
  using 64-bit-wide integers. The 32-bit version can be build and run on either
  32 or 64-bit hosts by either selecting or deselecting CONFIG_SANDBOX_32BIT; by
  default, the sandbox it built for a 32-bit host. The sandbox using 64-bit-wide
  integers can only be built on 64-bit hosts.

  Note that standalone/API support is not available at present.

  
  Basic Operation
  ---------------
  
  To run sandbox U-Boot use something like:

     make sandbox_defconfig all

     ./u-boot
  
  Note:
     If you get errors about 'sdl-config: Command not found' you may need to
     install libsdl1.2-dev or similar to get SDL support. Alternatively you can
     build sandbox without SDL (i.e. no display/keyboard support) by removing
     the CONFIG_SANDBOX_SDL line in include/configs/sandbox.h or using:

        make sandbox_defconfig all NO_SDL=1

        ./u-boot

  U-Boot will start on your computer, showing a sandbox emulation of the serial
  console:
  
  
  U-Boot 2014.04 (Mar 20 2014 - 19:06:00)
  
  DRAM:  128 MiB
  Using default environment
  
  In:    serial
  Out:   lcd
  Err:   lcd
  =>
  
  You can issue commands as your would normally. If the command you want is
  not supported you can add it to include/configs/sandbox.h.
  
  To exit, type 'reset' or press Ctrl-C.
  
  
  Console / LCD support
  ---------------------
  
  Assuming that CONFIG_SANDBOX_SDL is defined when building, you can run the
  sandbox with LCD and keyboard emulation, using something like:
  
     ./u-boot -d u-boot.dtb -l
  
  This will start U-Boot with a window showing the contents of the LCD. If
  that window has the focus then you will be able to type commands as you
  would on the console. You can adjust the display settings in the device
  tree file - see arch/sandbox/dts/sandbox.dts.
  
  
  Command-line Options
  --------------------
  
  Various options are available, mostly for test purposes. Use -h to see
  available options. Some of these are described below.
  
  The terminal is normally in what is called 'raw-with-sigs' mode. This means
  that you can use arrow keys for command editing and history, but if you
  press Ctrl-C, U-Boot will exit instead of handling this as a keypress.
  
  Other options are 'raw' (so Ctrl-C is handled within U-Boot) and 'cooked'
  (where the terminal is in cooked mode and cursor keys will not work, Ctrl-C
  will exit).
  
  As mentioned above, -l causes the LCD emulation window to be shown.
  
  A device tree binary file can be provided with -d. If you edit the source
  (it is stored at arch/sandbox/dts/sandbox.dts) you must rebuild U-Boot to
  recreate the binary file.
  
  To execute commands directly, use the -c option. You can specify a single
  command, or multiple commands separated by a semicolon, as is normal in
  U-Boot. Be careful with quoting as the shall will normally process and
  swallow quotes. When -c is used, U-Boot exists after the command is complete,
  but you can force it to go to interactive mode instead with -i.
  
  
  Memory Emulation
  ----------------
  
  Memory emulation is supported, with the size set by CONFIG_SYS_SDRAM_SIZE.
  The -m option can be used to read memory from a file on start-up and write
  it when shutting down. This allows preserving of memory contents across
  test runs. You can tell U-Boot to remove the memory file after it is read
  (on start-up) with the --rm_memory option.
  
  To access U-Boot's emulated memory within the code, use map_sysmem(). This
  function is used throughout U-Boot to ensure that emulated memory is used
  rather than the U-Boot application memory. This provides memory starting
  at 0 and extending to the size of the emulation.
  
  
  Storing State
  -------------
  
  With sandbox you can write drivers which emulate the operation of drivers on
  real devices. Some of these drivers may want to record state which is
  preserved across U-Boot runs. This is particularly useful for testing. For
  example, the contents of a SPI flash chip should not disappear just because
  U-Boot exits.
  
  State is stored in a device tree file in a simple format which is driver-
  specific. You then use the -s option to specify the state file. Use -r to
  make U-Boot read the state on start-up (otherwise it starts empty) and -w
  to write it on exit (otherwise the stored state is left unchanged and any
  changes U-Boot made will be lost). You can also use -n to tell U-Boot to
  ignore any problems with missing state. This is useful when first running
  since the state file will be empty.
  
  The device tree file has one node for each driver - the driver can store
  whatever properties it likes in there. See 'Writing Sandbox Drivers' below
  for more details on how to get drivers to read and write their state.
  
  
  Running and Booting
  -------------------
  
  Since there is no machine architecture, sandbox U-Boot cannot actually boot
  a kernel, but it does support the bootm command. Filesystems, memory
  commands, hashing, FIT images, verified boot and many other features are
  supported.
  
  When 'bootm' runs a kernel, sandbox will exit, as U-Boot does on a real
  machine. Of course in this case, no kernel is run.
  
  It is also possible to tell U-Boot that it has jumped from a temporary
  previous U-Boot binary, with the -j option. That binary is automatically
  removed by the U-Boot that gets the -j option. This allows you to write
  tests which emulate the action of chain-loading U-Boot, typically used in
  a situation where a second 'updatable' U-Boot is stored on your board. It
  is very risky to overwrite or upgrade the only U-Boot on a board, since a
  power or other failure will brick the board and require return to the
  manufacturer in the case of a consumer device.
  
  
  Supported Drivers
  -----------------
  
  U-Boot sandbox supports these emulations:
  
  - Block devices
  - Chrome OS EC
  - GPIO
  - Host filesystem (access files on the host from within U-Boot)

  - I2C

  - Keyboard (Chrome OS)
  - LCD

  - Network

  - Serial (for console only)
  - Sound (incomplete - see sandbox_sdl_sound_init() for details)
  - SPI
  - SPI flash
  - TPM (Trusted Platform Module)

  A wide range of commands is implemented. Filesystems which use a block
  device are supported.

  Also sandbox supports driver model (CONFIG_DM) and associated commands.

  Linux RAW Networking Bridge
  ---------------------------
  
  The sandbox_eth_raw driver bridges traffic between the bottom of the network
  stack and the RAW sockets API in Linux. This allows much of the U-Boot network
  functionality to be tested in sandbox against real network traffic.
  
  For Ethernet network adapters, the bridge utilizes the RAW AF_PACKET API.  This
  is needed to get access to the lowest level of the network stack in Linux. This
  means that all of the Ethernet frame is included. This allows the U-Boot network
  stack to be fully used. In other words, nothing about the Linux network stack is
  involved in forming the packets that end up on the wire. To receive the
  responses to packets sent from U-Boot the network interface has to be set to
  promiscuous mode so that the network card won't filter out packets not destined
  for its configured (on Linux) MAC address.
  
  The RAW sockets Ethernet API requires elevated privileges in Linux. You can
  either run as root, or you can add the capability needed like so:
  
  sudo /sbin/setcap "CAP_NET_RAW+ep" /path/to/u-boot
  
  The default device tree for sandbox includes an entry for eth0 on the sandbox
  host machine whose alias is "eth1". The following are a few examples of network
  operations being tested on the eth0 interface.
  
  sudo /path/to/u-boot -D
  
  DHCP
  ....
  
  set autoload no
  set ethact eth1
  dhcp
  
  PING
  ....
  
  set autoload no
  set ethact eth1
  dhcp
  ping $gatewayip
  
  TFTP
  ....
  
  set autoload no
  set ethact eth1
  dhcp
  set serverip WWW.XXX.YYY.ZZZ
  tftpboot u-boot.bin

  The bridge also support (to a lesser extent) the localhost inderface, 'lo'.
  
  The 'lo' interface cannot use the RAW AF_PACKET API because the lo interface
  doesn't support Ethernet-level traffic. It is a higher-level interface that is
  expected only to be used at the AF_INET level of the API. As such, the most raw
  we can get on that interface is the RAW AF_INET API on UDP. This allows us to
  set the IP_HDRINCL option to include everything except the Ethernet header in
  the packets we send and receive.
  
  Because only UDP is supported, ICMP traffic will not work, so expect that ping
  commands will time out.
  
  The default device tree for sandbox includes an entry for lo on the sandbox
  host machine whose alias is "eth5". The following is an example of a network
  operation being tested on the lo interface.
  
  TFTP
  ....
  
  set ethact eth5
  tftpboot u-boot.bin

  SPI Emulation
  -------------
  
  Sandbox supports SPI and SPI flash emulation.
  
  This is controlled by the spi_sf argument, the format of which is:
  
     bus:cs:device:file
  
     bus    - SPI bus number
     cs     - SPI chip select number
     device - SPI device emulation name
     file   - File on disk containing the data
  
  For example:
  
   dd if=/dev/zero of=spi.bin bs=1M count=4
   ./u-boot --spi_sf 0:0:M25P16:spi.bin
  
  With this setup you can issue SPI flash commands as normal:
  
  =>sf probe
  SF: Detected M25P16 with page size 64 KiB, total 2 MiB
  =>sf read 0 0 10000
  SF: 65536 bytes @ 0x0 Read: OK
  =>
  
  Since this is a full SPI emulation (rather than just flash), you can
  also use low-level SPI commands:
  
  =>sspi 0:0 32 9f
  FF202015
  
  This is issuing a READ_ID command and getting back 20 (ST Micro) part
  0x2015 (the M25P16).
  
  Drivers are connected to a particular bus/cs using sandbox's state
  structure (see the 'spi' member). A set of operations must be provided
  for each driver.
  
  
  Configuration settings for the curious are:
  
  CONFIG_SANDBOX_SPI_MAX_BUS
  	The maximum number of SPI buses supported by the driver (default 1).
  
  CONFIG_SANDBOX_SPI_MAX_CS
  	The maximum number of chip selects supported by the driver
  	(default 10).
  
  CONFIG_SPI_IDLE_VAL
  	The idle value on the SPI bus

  Block Device Emulation
  ----------------------
  
  U-Boot can use raw disk images for block device emulation. To e.g. list
  the contents of the root directory on the second partion of the image
  "disk.raw", you can use the following commands:
  
  =>host bind 0 ./disk.raw
  =>ls host 0:2
  
  A disk image can be created using the following commands:
  
  $> truncate -s 1200M ./disk.raw

  $> echo -e "label: gpt
  ,64M,U
  ,,L" | /usr/sbin/sgdisk  ./disk.raw

  $> lodev=`sudo losetup -P -f --show ./disk.raw`
  $> sudo mkfs.vfat -n EFI -v ${lodev}p1
  $> sudo mkfs.ext4 -L ROOT -v ${lodev}p2

  or utilize the device described in test/py/make_test_disk.py:
  
     #!/usr/bin/python
     import make_test_disk
     make_test_disk.makeDisk()

  Writing Sandbox Drivers
  -----------------------
  
  Generally you should put your driver in a file containing the word 'sandbox'
  and put it in the same directory as other drivers of its type. You can then
  implement the same hooks as the other drivers.
  
  To access U-Boot's emulated memory, use map_sysmem() as mentioned above.
  
  If your driver needs to store configuration or state (such as SPI flash
  contents or emulated chip registers), you can use the device tree as
  described above. Define handlers for this with the SANDBOX_STATE_IO macro.
  See arch/sandbox/include/asm/state.h for documentation. In short you provide
  a node name, compatible string and functions to read and write the state.
  Since writing the state can expand the device tree, you may need to use
  state_setprop() which does this automatically and avoids running out of
  space. See existing code for examples.
  
  
  Testing
  -------
  
  U-Boot sandbox can be used to run various tests, mostly in the test/
  directory. These include:
  
    command_ut
       - Unit tests for command parsing and handling
    compression
       - Unit tests for U-Boot's compression algorithms, useful for
         security checking. It supports gzip, bzip2, lzma and lzo.
    driver model

       - Run this pytest
  	  ./test/py/test.py --bd sandbox --build -k ut_dm -v

    image
       - Unit tests for images:
            test/image/test-imagetools.sh - multi-file images
            test/image/test-fit.py        - FIT images
    tracing
       - test/trace/test-trace.sh tests the tracing system (see README.trace)
    verified boot
        - See test/vboot/vboot_test.sh for this
  
  If you change or enhance any of the above subsystems, you shold write or
  expand a test and include it with your patch series submission. Test
  coverage in U-Boot is limited, as we need to work to improve it.
  
  Note that many of these tests are implemented as commands which you can
  run natively on your board if desired (and enabled).
  
  It would be useful to have a central script to run all of these.

  --
  Simon Glass <sjg@chromium.org>
  Updated 22-Mar-14