How to load U-Boot with dfu-util

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This page explains how to load and start U-Boot with the dfu-util[1] tool over a USB port.

This tool, available on Linux or Windows, supports the DFU standard [2] and can replace STM32CubeProgrammer for the U-Boot load use case.

1 Overview[edit]

To load and execute U-Boot in DDR with the DFU protocol, the dfu-util tools can be used instead of STM32CubeProgrammer.

As the GetPhase is an STMicroelectronics protocol for STM32CubeProgrammer and is not supported by dfu-util, you must follow the steps described in AN5275: USB DFU/USART protocols used in STM32MP1 Series bootloaders and provide the binaries in the order expected by the bootloaders:

  1. Download phase 0x1 by ROM code is the FSBL (TF-A BL2)
  2. Download phase 0x0 by FSBL is the flashlayout (mandatory on STM32MP15x)
  3. Download phase 0x3 by FSBL is the FIP file including the SSBL image (U-Boot)
  4. DFU detach to request an SSBL start

The FSBL, SSBL and FIP definitions can be found in the Boot chain overview.

The FIP includes the required SSBL = U-Boot, see How to configure TF-A FIP in order to update it with the U-Boot binary.

This feature can be used to debug U-Boot during board bring-up.

See also How to load U-Boot with STM32CubeProgrammer.

2 dfu-util[edit]

The help message of dfu-util is:

 PC $>  dfu-util --help
 Usage: dfu-util [options] ...
   -h --help			Print this help message
   -V --version			Print the version number
   -v --verbose			Print verbose debug statements
   -l --list			List currently attached DFU capable devices
   -e --detach			Detach currently attached DFU capable devices
   -E --detach-delay seconds	Time to wait before reopening a device after detach
   -d --device <vendor>:<product>[,<vendor_dfu>:<product_dfu>]
 				Specify Vendor/Product ID(s) of DFU device
   -p --path <bus-port. ... .port>	Specify path to DFU device
   -c --cfg <config_nr>		Specify the Configuration of DFU device
   -i --intf <intf_nr>		Specify the DFU Interface number
   -S --serial <serial_string>[,<serial_string_dfu>]
 				Specify Serial String of DFU device
   -a --alt <alt>		Specify the Altsetting of the DFU Interface
 				by name or by number
   -t --transfer-size <size>	Specify the number of bytes per USB Transfer
   -U --upload <file>		Read firmware from device into <file>
   -Z --upload-size <bytes>	Specify the expected upload size in bytes
   -D --download <file>		Write firmware from <file> into device
   -R --reset			Issue USB Reset signalling once we're finished
   -s --dfuse-address <address>	ST DfuSe mode, specify target address for
 				raw file download or upload. Not applicable for
 				DfuSe file (.dfu) downloads

The minimal dfu-util option used to load U-Boot is:

  • -a"/'--alt select the alternate to load the requested phase
  • -D/--download Download the requested binary for the selected phase
  • -e/--detach request a DFU DETACH

3 Identify alternate[edit]

You can also use the -l/--list option to check the alternate associated to each phase.

For example the command result on the STM32MP15x with a USB serial boot is:

 PC $> dfu-util -l
 dfu-util 0.9
 
 Copyright 2005-2009 Weston Schmidt, Harald Welte and OpenMoko Inc.
 Copyright 2010-2016 Tormod Volden and Stefan Schmidt
 This program is Free Software and has ABSOLUTELY NO WARRANTY
 Please report bugs to http://sourceforge.net/p/dfu-util/tickets/
 
 Found DFU: [0483:df11] ver=0200, devnum=12, cfg=1, intf=0, path="1-5.2", alt=5, name="@virtual /0xF1/1*512Ba", 
 serial="004100323338511634383330"
 Found DFU: [0483:df11] ver=0200, devnum=12, cfg=1, intf=0, path="1-5.2", alt=4, name="@Partition4 /0x04/1*16Me", 
 serial="004100323338511634383330"
 Found DFU: [0483:df11] ver=0200, devnum=12, cfg=1, intf=0, path="1-5.2", alt=3, name="@Partition3 /0x03/1*16Me", 
 serial="004100323338511634383330"
 Found DFU: [0483:df11] ver=0200, devnum=12, cfg=1, intf=0, path="1-5.2", alt=2, name="@Partition2 /0x02/1*1Me", 
 serial="004100323338511634383330"
 Found DFU: [0483:df11] ver=0200, devnum=12, cfg=1, intf=0, path="1-5.2", alt=1, name="@FSBL /0x01/1*1Me", 
 serial="004100323338511634383330"
 Found DFU: [0483:df11] ver=0200, devnum=12, cfg=1, intf=0, path="1-5.2", alt=0, name="@Partition0 /0x00/1*256Ke", 
 serial="004100323338511634383330"

The alternate is alt=1 for FSB alternate associate to phase 0x1 (see AN5275 for the coding of the alternate name).

4 Select device[edit]

In each dfu-util command, the command device can be identified by:

  • USB vendor and product identifiers (VID and PID)
  • USB serial number

In the previous example, the device has VID:PID=0483:df11 and its serial number is 004100323338511634383330.

In the following sections, you can add the -d"/'--device and -S/--serial options to select this specific device:

 PC $> dfu-util -d 0483:df11 -S 004100323338511634383330 ....

5 Generate an empty flashlayout[edit]

You can generate this empty flashlayout.stm32 file, which is required by the STM32MP15x TF-A, with a U-Boot mkimage by using the following Linux shell commands:

PC $> echo "" > flashlayout.tsv
PC $> mkimage -T stm32image -a 0xC0000000 -e 0xC0000000 -d flashlayout.tsv flashlayout.stm32

6 The U-Boot load sequence[edit]

 PC $> dfu-util -a 1 -D tf-a.bin
 PC $> dfu-util -a 0 -D flashlayout.stm32
 PC $> dfu-util -a 3 -D fip.bin
 PC $> dfu-util -a 0 -e

7 Generate a U-Boot script[edit]

You can replace the flashlayout file with a U-Boot script containing a U-Boot image header. This is then executed automatically by U-Boot.

The following example is for a simple script to start U-Boot in dfu mode and then reset:

 dfu 0
 reset
PC $> echo "dfu 0; reset" > script.cmd
PC $> mkimage -C none -A arm -T script -d script.cmd script.uimg
PC $> mkimage -T stm32image -a 0xC0000000 -e 0xC0000000 -d script.uimg script.stm32

Then the sequence is:

 PC $> dfu-util -a 1 -D tf-a.bin
 PC $> dfu-util -a 0 -D script.stm32
 PC $> dfu-util -a 3 -D fip.bin
 PC $> dfu-util -a 0 -e

8 References[edit]

  1. dfu-util - Device Firmware Upgrade Utilities - http://dfu-util.sourceforge.net
  2. USB DFU - Universal Serial Bus Device Class Specification for Device Firmware Upgrade Version 1.1 - https://usb.org/sites/default/files/DFU_1.1.pdf