xref: /openbmc/u-boot/board/sandbox/README.sandbox (revision 887363b5)
1/*
2 * Copyright (c) 2014 The Chromium OS Authors.
3 *
4 * SPDX-License-Identifier:	GPL-2.0+
5 */
6
7Native Execution of U-Boot
8==========================
9
10The 'sandbox' architecture is designed to allow U-Boot to run under Linux on
11almost any hardware. To achieve this it builds U-Boot (so far as possible)
12as a normal C application with a main() and normal C libraries.
13
14All of U-Boot's architecture-specific code therefore cannot be built as part
15of the sandbox U-Boot. The purpose of running U-Boot under Linux is to test
16all the generic code, not specific to any one architecture. The idea is to
17create unit tests which we can run to test this upper level code.
18
19CONFIG_SANDBOX is defined when building a native board.
20
21The chosen vendor and board names are also 'sandbox', so there is a single
22board in board/sandbox.
23
24CONFIG_SANDBOX_BIG_ENDIAN should be defined when running on big-endian
25machines.
26
27Note that standalone/API support is not available at present.
28
29
30Basic Operation
31---------------
32
33To run sandbox U-Boot use something like:
34
35   make sandbox_defconfig all
36   ./u-boot
37
38Note:
39   If you get errors about 'sdl-config: Command not found' you may need to
40   install libsdl1.2-dev or similar to get SDL support. Alternatively you can
41   build sandbox without SDL (i.e. no display/keyboard support) by removing
42   the CONFIG_SANDBOX_SDL line in include/configs/sandbox.h or using:
43
44      make sandbox_defconfig all NO_SDL=1
45      ./u-boot
46
47
48U-Boot will start on your computer, showing a sandbox emulation of the serial
49console:
50
51
52U-Boot 2014.04 (Mar 20 2014 - 19:06:00)
53
54DRAM:  128 MiB
55Using default environment
56
57In:    serial
58Out:   lcd
59Err:   lcd
60=>
61
62You can issue commands as your would normally. If the command you want is
63not supported you can add it to include/configs/sandbox.h.
64
65To exit, type 'reset' or press Ctrl-C.
66
67
68Console / LCD support
69---------------------
70
71Assuming that CONFIG_SANDBOX_SDL is defined when building, you can run the
72sandbox with LCD and keyboard emulation, using something like:
73
74   ./u-boot -d u-boot.dtb -l
75
76This will start U-Boot with a window showing the contents of the LCD. If
77that window has the focus then you will be able to type commands as you
78would on the console. You can adjust the display settings in the device
79tree file - see arch/sandbox/dts/sandbox.dts.
80
81
82Command-line Options
83--------------------
84
85Various options are available, mostly for test purposes. Use -h to see
86available options. Some of these are described below.
87
88The terminal is normally in what is called 'raw-with-sigs' mode. This means
89that you can use arrow keys for command editing and history, but if you
90press Ctrl-C, U-Boot will exit instead of handling this as a keypress.
91
92Other options are 'raw' (so Ctrl-C is handled within U-Boot) and 'cooked'
93(where the terminal is in cooked mode and cursor keys will not work, Ctrl-C
94will exit).
95
96As mentioned above, -l causes the LCD emulation window to be shown.
97
98A device tree binary file can be provided with -d. If you edit the source
99(it is stored at arch/sandbox/dts/sandbox.dts) you must rebuild U-Boot to
100recreate the binary file.
101
102To execute commands directly, use the -c option. You can specify a single
103command, or multiple commands separated by a semicolon, as is normal in
104U-Boot. Be careful with quoting as the shall will normally process and
105swallow quotes. When -c is used, U-Boot exists after the command is complete,
106but you can force it to go to interactive mode instead with -i.
107
108
109Memory Emulation
110----------------
111
112Memory emulation is supported, with the size set by CONFIG_SYS_SDRAM_SIZE.
113The -m option can be used to read memory from a file on start-up and write
114it when shutting down. This allows preserving of memory contents across
115test runs. You can tell U-Boot to remove the memory file after it is read
116(on start-up) with the --rm_memory option.
117
118To access U-Boot's emulated memory within the code, use map_sysmem(). This
119function is used throughout U-Boot to ensure that emulated memory is used
120rather than the U-Boot application memory. This provides memory starting
121at 0 and extending to the size of the emulation.
122
123
124Storing State
125-------------
126
127With sandbox you can write drivers which emulate the operation of drivers on
128real devices. Some of these drivers may want to record state which is
129preserved across U-Boot runs. This is particularly useful for testing. For
130example, the contents of a SPI flash chip should not disappear just because
131U-Boot exits.
132
133State is stored in a device tree file in a simple format which is driver-
134specific. You then use the -s option to specify the state file. Use -r to
135make U-Boot read the state on start-up (otherwise it starts empty) and -w
136to write it on exit (otherwise the stored state is left unchanged and any
137changes U-Boot made will be lost). You can also use -n to tell U-Boot to
138ignore any problems with missing state. This is useful when first running
139since the state file will be empty.
140
141The device tree file has one node for each driver - the driver can store
142whatever properties it likes in there. See 'Writing Sandbox Drivers' below
143for more details on how to get drivers to read and write their state.
144
145
146Running and Booting
147-------------------
148
149Since there is no machine architecture, sandbox U-Boot cannot actually boot
150a kernel, but it does support the bootm command. Filesystems, memory
151commands, hashing, FIT images, verified boot and many other features are
152supported.
153
154When 'bootm' runs a kernel, sandbox will exit, as U-Boot does on a real
155machine. Of course in this case, no kernel is run.
156
157It is also possible to tell U-Boot that it has jumped from a temporary
158previous U-Boot binary, with the -j option. That binary is automatically
159removed by the U-Boot that gets the -j option. This allows you to write
160tests which emulate the action of chain-loading U-Boot, typically used in
161a situation where a second 'updatable' U-Boot is stored on your board. It
162is very risky to overwrite or upgrade the only U-Boot on a board, since a
163power or other failure will brick the board and require return to the
164manufacturer in the case of a consumer device.
165
166
167Supported Drivers
168-----------------
169
170U-Boot sandbox supports these emulations:
171
172- Block devices
173- Chrome OS EC
174- GPIO
175- Host filesystem (access files on the host from within U-Boot)
176- Keyboard (Chrome OS)
177- LCD
178- Serial (for console only)
179- Sound (incomplete - see sandbox_sdl_sound_init() for details)
180- SPI
181- SPI flash
182- TPM (Trusted Platform Module)
183
184Notable omissions are networking and I2C.
185
186A wide range of commands is implemented. Filesystems which use a block
187device are supported.
188
189Also sandbox uses generic board (CONFIG_SYS_GENERIC_BOARD) and supports
190driver model (CONFIG_DM) and associated commands.
191
192
193SPI Emulation
194-------------
195
196Sandbox supports SPI and SPI flash emulation.
197
198This is controlled by the spi_sf argument, the format of which is:
199
200   bus:cs:device:file
201
202   bus    - SPI bus number
203   cs     - SPI chip select number
204   device - SPI device emulation name
205   file   - File on disk containing the data
206
207For example:
208
209 dd if=/dev/zero of=spi.bin bs=1M count=4
210 ./u-boot --spi_sf 0:0:M25P16:spi.bin
211
212With this setup you can issue SPI flash commands as normal:
213
214=>sf probe
215SF: Detected M25P16 with page size 64 KiB, total 2 MiB
216=>sf read 0 0 10000
217SF: 65536 bytes @ 0x0 Read: OK
218=>
219
220Since this is a full SPI emulation (rather than just flash), you can
221also use low-level SPI commands:
222
223=>sspi 0:0 32 9f
224FF202015
225
226This is issuing a READ_ID command and getting back 20 (ST Micro) part
2270x2015 (the M25P16).
228
229Drivers are connected to a particular bus/cs using sandbox's state
230structure (see the 'spi' member). A set of operations must be provided
231for each driver.
232
233
234Configuration settings for the curious are:
235
236CONFIG_SANDBOX_SPI_MAX_BUS
237	The maximum number of SPI buses supported by the driver (default 1).
238
239CONFIG_SANDBOX_SPI_MAX_CS
240	The maximum number of chip selects supported by the driver
241	(default 10).
242
243CONFIG_SPI_IDLE_VAL
244	The idle value on the SPI bus
245
246
247Writing Sandbox Drivers
248-----------------------
249
250Generally you should put your driver in a file containing the word 'sandbox'
251and put it in the same directory as other drivers of its type. You can then
252implement the same hooks as the other drivers.
253
254To access U-Boot's emulated memory, use map_sysmem() as mentioned above.
255
256If your driver needs to store configuration or state (such as SPI flash
257contents or emulated chip registers), you can use the device tree as
258described above. Define handlers for this with the SANDBOX_STATE_IO macro.
259See arch/sandbox/include/asm/state.h for documentation. In short you provide
260a node name, compatible string and functions to read and write the state.
261Since writing the state can expand the device tree, you may need to use
262state_setprop() which does this automatically and avoids running out of
263space. See existing code for examples.
264
265
266Testing
267-------
268
269U-Boot sandbox can be used to run various tests, mostly in the test/
270directory. These include:
271
272  command_ut
273     - Unit tests for command parsing and handling
274  compression
275     - Unit tests for U-Boot's compression algorithms, useful for
276       security checking. It supports gzip, bzip2, lzma and lzo.
277  driver model
278     - test/dm/test-dm.sh to run these.
279  image
280     - Unit tests for images:
281          test/image/test-imagetools.sh - multi-file images
282          test/image/test-fit.py        - FIT images
283  tracing
284     - test/trace/test-trace.sh tests the tracing system (see README.trace)
285  verified boot
286      - See test/vboot/vboot_test.sh for this
287
288If you change or enhance any of the above subsystems, you shold write or
289expand a test and include it with your patch series submission. Test
290coverage in U-Boot is limited, as we need to work to improve it.
291
292Note that many of these tests are implemented as commands which you can
293run natively on your board if desired (and enabled).
294
295It would be useful to have a central script to run all of these.
296
297--
298Simon Glass <sjg@chromium.org>
299Updated 22-Mar-14
300