u-boot/doc/kwboot.1

.TH KWBOOT 1 "2022-03-02"

.SH NAME
kwboot \- Boot Marvell Kirkwood (and others 32-bit) SoCs over a serial link.
.SH SYNOPSIS
.B kwboot
.RB [ "-b \fIimage\fP" ]
.RB [ "-t" ]
.RB [ "-B \fIbaudrate\fP" ]
.RB \fITTY\fP
.SH "DESCRIPTION"

The \fBkwboot\fP program boots boards based on Marvell's 32-bit
platforms including Kirkwood, Dove, Avanta, A370, AXP, A375, A38x
and A39x over their integrated UART. Boot image files will typically
contain a second stage boot loader, such as U-Boot. The image file
must conform to Marvell's BootROM firmware image format
(\fIkwbimage v0\fP or \fIv1\fP), created using a tool such as
\fBmkimage\fP.

Following power-up or a system reset, system BootROM code polls the
UART for a brief period of time, sensing a handshake message which
initiates an image upload. This program sends this boot message until
it receives a positive acknowledgement. The image is transferred using
Xmodem.

Additionally, this program implements a minimal terminal mode, which
can be used either standalone, or entered immediately following boot
image transfer completion. This is often useful to catch early boot
messages, or to manually interrupt a default boot procedure performed
by the second-stage loader.

.SH "OPTIONS"

.TP
.BI "\-b \fIimage\fP"
Handshake; then upload file \fIimage\fP over \fITTY\fP.

Note that for the encapsulated boot code to be executed, \fIimage\fP
must be of type "UART boot" (0x69). The \fBkwboot\fP program changes
this type automatically, unless the \fIimage\fP is signed, in which
case it cannot be changed.

This mode writes handshake status and upload progress indication to
stdout. It is possible that \fIimage\fP contains an optional binary
code in it's header which may also print some output via UART (for
example U-Boot SPL does this). In such a case, this output is also
written to stdout after the header is sent.

.TP
.B "\-b"
Do only handshake on \fITTY\fP without uploading any file. File upload
could be done later via option \fB\-D\fP or via any other Xmodem
application, like \fBsx\fP(1).

.TP
.B "\-d"
Do special handshake on \fITTY\fP for console debug mode.

This will instruct BootROM to enter builtin simple console debug mode.
Should be combined with option \fB\-t\fP.

To get a BootROM help, type this command followed by ENTER key:

.RS 1.2i
.TP
.B ?
.RE
.IP

Armada 38x BootROM has a bug which cause that BootROM's standard output
is turned off on UART when SPI-NOR contains valid boot image. Nevertheless
BootROM's standard input and BootROM's terminal echo are active and working
fine. To workaround this BootROM bug with standard output, it is possible
to manually overwrite BootROM variables stored in SRAM which BootROM use
for checking if standard output is enabled or not. To enable BootROM
standard output on UART, type this command followed by ENTER key:

.RS 1.2i
.TP
.B w 0x40034100 1
.RE

.TP
.BI "\-D" " image"
Upload file \fIimage\fP over \fITTY\fP without initial handshake.

This method is used primary on Dove platforms, where BootROM does
not support initial handshake for entering UART upload mode and
strapping pins (exported via e.g. buttons) are used instead.

.TP
.BI "\-p"
Obsolete. Does nothing.

In the past, when this option was used, the program patched the header
in the image prior upload, to "UART boot" type. This is now done by
default.

.TP
.B "\-q"
Obsolete. Does nothing.

It is unknown whether it did something in the past.

.TP
.BI "\-s" " response-timeout"
Specify custom response timeout when doing handshake. Default value is 50 ms.
It is the timeout between sending two consecutive handshake patterns, meaning
how long to wait for response from BootROM. Affects only option \fB\-b\fP with
image file and option \fB\-d\fP.

Option \fB-a\fP specify response timeout suitable for Armada XP BootROM and
currently it is 1000 ms.

Some testing showed that specifying 24 ms as response timeout make handshake
with Armada 385 BootROM more stable.

.TP
.BI "\-t"
Run a terminal program, connecting standard input and output to
.RB \fITTY\fP.

If used in combination with \fB\-b\fP, \fB\-D\fP or \fB\-d\fP option,
terminal mode is entered immediately following a successful image upload
or successful handshake (if not doing image upload).

If standard I/O streams connect to a console, this mode will terminate
after receiving \fBctrl-\e\fP followed by \fBc\fP from console input.

.TP
.BI "\-B \fIbaudrate\fP"
If used in combination with \fB-b\fP, inject into the image header
code that changes baud rate to \fIbaudrate\fP after uploading image
header, and code that changes the baud rate back to the default
(115200 Bd) before executing payload, and also adjust the baud rate
on \fITTY\fP correspondingly. This can make the upload significantly
faster.

If used in combination with \fB-t\fP, adjust the baud rate to
\fIbaudrate\fP on \fITTY\fP before starting terminal.

If both \fB-b\fP and \fB-t\fP are used, the baud rate is changed
back to 115200 after the upload.

Tested values for \fIbaudrate\fP for Armada 38x include: 115200,
230400, 460800, 500000, 576000, 921600, 1000000, 1152000, 1500000,
2000000, 2500000, 3125000, 4000000 and 5200000.

.SH "EXAMPLES"

Instruct BootROM to enter boot Xmodem boot mode, send \fIu-boot-spl.kwb\fP
kwbimage file via Xmodem on \fI/dev/ttyUSB0\fP at 115200 Bd and run terminal
program:
.IP
.B kwboot -b u-boot-spl.kwb -t /dev/ttyUSB0

.PP
Instruct BootROM to enter boot Xmodem boot mode, send header of
\fIu-boot-spl.kwb\fP kwbimage file via Xmodem at 115200 Bd, then instruct
BootROM to change baudrate to 5200000 Bd, send data part of the kwbimage
file via Xmodem at high speed and finally run terminal program:
.IP
.B kwboot -b u-boot-spl.kwb -B 5200000 -t /dev/ttyUSB0

.PP
Only send \fIu-boot-spl.kwb\fP kwbimage file via Xmodem on \fI/dev/ttyUSB0\fP
at 115200 Bd:
.IP
.B kwboot -D u-boot-spl.kwb /dev/ttyUSB0

.PP
Instruct BootROM to enter console debug mode and run terminal program on
\fI/dev/ttyUSB0\fP at 115200 Bd:
.IP
.B kwboot -d -t /dev/ttyUSB0

.PP
Only run terminal program on \fI/dev/ttyUSB0\fP at 115200 Bd:
.IP
.B kwboot -t /dev/ttyUSB0

.SH "SEE ALSO"
.PP
\fBmkimage\fP(1), \fBsx\fP(1)

.SH "AUTHORS"

Daniel Stodden <daniel.stodden@gmail.com>
.br
Luka Perkov <luka@openwrt.org>
.br
David Purdy <david.c.purdy@gmail.com>
.br
Pali Rohár <pali@kernel.org>
.br
Marek Behún <kabel@kernel.org>