Booting Linux from SPI Flash on SC58x & SC573

📝	The instructions are applicable to Linux for ADSP-SC5xx Processors 3.0.0 or later

The ADSP-SC58x-EZKIT & ADSP-SC573-EZKIT come equipped with 16 MiB of SPI Flash. The adsp-sc5xx-tiny image can be stored into it and used to boot Linux from it. To do that, you need to change the Libc implementation from the default GNU to musl, to further reduce the image's size.

Change the Libc implementation

Changing the Libc implementation is a simple edit in the $YOUR_PROJECT_DIR/build/conf/local.conf file, from DISTRO ?= "adi-distro-glibc" to DISTRO ?= "adi-distro-musl".

Build the tiny image

Following the Quickstart guide for your target board in the Landing Pages, use

$ bitbake adsp-sc5xx-tiny

Build and install the SDK

📝	The ADSP-SC584-EZKIT has been chosen as the example for these instructions, and will appear on filenames and paths etc.

The SDK will provide you with the cross toolchain needed to develop application for the target board, alongside various miscellaneous tools. Notably, it will provide you with OpenOCD and GDB, which you can use to run and flash U-Boot on the board.

The SDK can be built for the adsp-sc5xx-minimal image or the adsp-sc5xx-full image. To build the SDK for the adsp-sc5xx-minimal image invoke bitbake from within the build directory created previously.

$ bitbake adsp-sc5xx-minimal -c populate_sdk

or for the adsp-sc5xx-full image

$ bitbake adsp-sc5xx-full -c populate_sdk

When the build has completed you will find a set of files in the <BUILD_DIR>/tmp/deploy/sdk directory. For example, the minimal image on SC584-EZKIT:

$ ls tmp/deploy/sdk
adi-distro-musl-x86_64-adsp-sc5xx-minimal-cortexa5t2hf-neon-adsp-sc584-ezkit-toolchain-3.0.0.host.manifest
adi-distro-musl-x86_64-adsp-sc5xx-minimal-cortexa5t2hf-neon-adsp-sc584-ezkit-toolchain-3.0.0.sh
adi-distro-musl-x86_64-adsp-sc5xx-minimal-cortexa5t2hf-neon-adsp-sc584-ezkit-toolchain-3.0.0.target.manifest
adi-distro-musl-x86_64-adsp-sc5xx-minimal-cortexa5t2hf-neon-adsp-sc584-ezkit-toolchain-3.0.0.testdata.json

The adi-distro-glibc-glibc-x86_64-adsp-sc5xx-minimal-cortexa5t2hf-neon-adsp-sc584-ezkit-toolchain-3.0.0.sh is a self-extracting archive containing the SDK.

Invoke the self-extracting archive. It will default to installing to /opt/adi-distro-musl/3.0.0 but gives you the option to select your own install folder during the installation. For the minimal image on SC589-EZKIT

$ ./adi-distro-musl-x86_64-adsp-sc5xx-minimal-cortexa5t2hf-neon-adsp-sc589-ezkit-toolchain-3.0.0.sh
Analog Devices Inc Reference Distro SDK installer version 3.0.0
===============================================================
Enter target directory for SDK (default: /opt/adi-distro-musl/3.0.0):
You are about to install the SDK to "/opt/adi-distro-musl/3.0.0". Proceed [Y/n]? y
Extracting SDK........................................................................done
Setting it up...done
SDK has been successfully set up and is ready to be used.
Each time you wish to use the SDK in a new shell session, you need to source the environment setup script e.g.

 $ . /opt/adi-distro-musl/3.0.0/environment-setup-cortexa5t2hf-neon-adi-linux-musleabi
Your SDK is now installed.

Running U-Boot on the Board for the first time

📝	It's always good practice to erase the contents of `/tftpboot/` before running and/or flashing a new build of U-Boot or Linux. You can do so by executing `rm /tftpboot/*` before proceeding

Copy the U-Boot binary & loader files to the tftp directory:

$ cp tmp/deploy/images/adsp-sc584-ezkit/u-boot-spl-sc584-ezkit.elf /tftpboot/ 
$ cp tmp/deploy/images/adsp-sc584-ezkit/u-boot-proper-sc584-ezkit.elf /tftpboot/ 
$ cp tmp/deploy/images/adsp-sc584-ezkit/stage1-boot.ldr /tftpboot/ 
$ cp tmp/deploy/images/adsp-sc584-ezkit/stage2-boot.ldr /tftpboot/

Before installing the software on to the development board, ensure that the following cables are connected:

Board connected to network via ethernet cable using J13 connector.
Board connected to host PC using USB micro cable, connected to USB/UART port on the development board
Board connected to the ICE 1000 or ICE 2000 via the DEBUG port on the board
ICE is also connected to host PC via USB mini cable

The BOOT MODE selector on the SC584 board should be turned to "0".

The console output from U-Boot and later on Linux will appear on the USB serial port configured in minicom earlier so open up minicom. Terminal1: minicom

$ sudo minicom

In a separate console launch OpenOCD and connect to the development board.

Terminal2: OpenOCD

$ sdk_usr=/opt/adi-distro-glibc/3.0.0/sysroots/x86_64-adi_glibc_sdk-linux/usr/
$ $sdk_usr/bin/openocd -f $sdk_usr/share/openocd/scripts/interface/<ICE>.cfg -f $sdk_usr/share/openocd/scripts/target/adspsc58x.cfg

Where <ICE> should be replaced with ice1000 or ice2000 depending on your hardware.

When successful you should see a message similar to the console output below

Terminal2: OpenOCD

Open On-Chip Debugger (PKGVERSION)  OpenOCD 0.10.0-g40378454d (2023-04-05-10:35)
Licensed under GNU GPL v2
Report bugs to <[email protected]>
adapter speed: 1000 kHz
Info : transports supported by the debug adapter: "jtag", "swd"
Info : auto-select transport "jtag"
halt and restart using CTI
trst_only separate trst_push_pull
adspsc58x_init
Info : ICE-1000 firmware version is 1.0.2
Info : clock speed 1000 kHz
Info : JTAG tap: adspsc584.adjc tap/device found: 0x428080cb (mfg: 0x065, part: 0x2808, ver: 0x4)
Info : JTAG tap: adspsc584.dap enabled
Info : adspsc584.dap: hardware has 3 breakpoints, 2 watchpoints
Info : adspsc584.dap: but you can only set 1 watchpoint
Info : accepting 'gdb' connection on tcp/3333
Info : JTAG tap: adspsc584.adjc tap/device found: 0x428080cb (mfg: 0x065, part: 0x2808, ver: 0x4)
Info : JTAG tap: adspsc584.dap enabled
Info : adspsc584.dap: hardware has 3 breakpoints, 2 watchpoints
Info : adspsc584.dap: but you can only set 1 watchpoint

In a third console window launch GDB and type target extended-remote :3333. This will make GDB to connect to the gdbserver on the local host using port 3333. Then, load the U-Boot SPL into RAM by typing load. Hit Ctrl+C to interrupt thereafter.

Terminal3: GDB

$ cd /tftpboot
$ /opt/adi-distro-glibc/3.0.0/sysroots/x86_64-adi_glibc_sdk-linux/usr/bin/arm-adi_glibc-linux-gnueabi/arm-adi_glibc-linux-gnueabi-gdb u-boot-spl-sc584-ezkit.elf
...
(gdb) target extended-remote :3333
Remote debugging using :3333
0x00004884 in ?? ()
(gdb) load
Loading section .text, size 0x9c0c lma 0x20080000
Loading section .rodata, size 0x1198 lma 0x20089c0c
Loading section .dtb.init.rodata, size 0x1460 lma 0x2008adb0
Loading section .data, size 0x514 lma 0x2008c210
Loading section .u_boot_list, size 0xa50 lma 0x2008c724
Start address 0x20080000, load size 53608
Transfer rate: 29 KB/sec, 7658 bytes/write.
(gdb) c
Continuing.
^C
Program received signal SIGINT, Interrupt.

You will see a message on Terminal 1 running minicom, informing you that you can now load U-Boot Proper

Terminal1: minicom

U-Boot SPL 2020.10 (Mar 16 2023 - 13:07:24 +0000)
ADI Boot Mode: 0x0 (JTAG/BOOTROM)
SPL execution has completed.  Please load U-Boot Proper via JTAG

Now, load U-Boot Proper into RAM.

Terminal3: GDB

(gdb) load u-boot-proper-sc584-ezkit.elf
Loading section .text, size 0x3a8 lma 0x89200000
Loading section .text_rest, size 0x46084 lma 0x892003c0
Loading section .rodata, size 0xf56c lma 0x89246444
Loading section .hash, size 0x18 lma 0x892559b0
Loading section .dtb.init.rodata, size 0x19d0 lma 0x892559d0
Loading section .data, size 0x22d8 lma 0x892573a0
Loading section .got.plt, size 0xc lma 0x89259678
Loading section .u_boot_list, size 0x1644 lma 0x89259684
Loading section .rel.dyn, size 0x9c98 lma 0x8925acc8
Loading section .dynsym, size 0x30 lma 0x89264960
Loading section .dynstr, size 0x1 lma 0x89264990
Loading section .dynamic, size 0x90 lma 0x89264994
Loading section .gnu.hash, size 0x18 lma 0x89264a24
Start address 0x89200000, load size 412185
Transfer rate: 30 KB/sec, 11776 bytes/write.
(gdb) c
Continuing.

At this point U-Boot will now be running in RAM on your target board. You should see U-Boot booting in the minicom console (Terminal 1). Press a key to interrupt the boot process before the countdown terminates: Terminal1: minicom

U-Boot 2020.10 (Mar 16 2023 - 13:07:24 +0000)

CPU:   ADSP ADSP-SC584-0.1 (spi flash boot)
Detected Revision: 1.1
Model: ADI sc584-ezkit
DRAM:  112 MiB
WDT:   Not found!
MMC:
Loading Environment from SPIFlash... SF: Detected w25q128 with page size 256 Bytes, erase size 4 KiB, total 16 MiB
*** Warning - bad CRC, using default environment

In:    serial@0x31003000
Out:   serial@0x31003000
Err:   serial@0x31003000
Net:   eth0: eth0
Hit any key to stop autoboot:  0
=>

Flash U-Boot to SPI Flash

In the U-Boot console, set the IP address of the Linux PC that hosts the U-Boot loader files (stage1-boot.ldr & stage2-boot.ldr) on TFTP. Terminal1: minicom

=> setenv serverip <SERVERIP>
=> setenv tftpserverip <SERVERIP>

📝	To find the IP address of your host Linux PC you can issue the `ip addr` command from the shell or console.

If your network supports DHCP, run:

=> dhcp

If your network does NOT support DHCP, in the U-Boot console configure the board IP address you want the board to be assigned with (<IPADDR>) and remove "dhcp;" from the "init_ethernet" command:

=> setenv ipaddr <IPADDR>
=> edit init_ethernet
=> edit: mii info; <remove "dhcp;" from here>; setenv serverip ${tftpserverip};
=> saveenv

i.e. init_ethernet should now be init_ethernet=mii info; setenv serverip ${tftpserverip};, where prior to this change it was init_ethernet=mii info; dhcp; setenv serverip ${tftpserverip};

📝	If flashing a board that had been previously programmed, it's good to erase the whole flash before as sometimes previous U-Boot installations might leave remnants. You can do that by typing `=> sf probe ${sfdev}; sf erase 0 0x4000000` on the U-Boot prompt before proceeding to the following instructions

Next, run the U-Boot update command to copy the U-Boot loader files from the host PC to the target board, and write it into flash:

=> run update_spi_uboot_only

You will see an output similar to the one below:

=> run update_spi_uboot_only
Speed: 1000, full duplex
Using eth0 device
TFTP from server 10.37.33.116; our IP address is 10.37.33.113
Filename 'stage1-boot.ldr'.
Load address: 0x89000000
Loading: ####
         2.2 MiB/s
done
Bytes transferred = 53684 (d1b4 hex)
SF: Detected w25q128 with page size 256 Bytes, erase size 4 KiB, total 16 MiB
device 0 offset 0x0, size 0xd1b4
SF: 53684 bytes @ 0x0 Written: OK
Speed: 1000, full duplex
Using eth0 device
TFTP from server 10.37.33.116; our IP address is 10.37.33.113
Filename 'stage2-boot.ldr'.
Load address: 0x89000000
Loading: #############################
         2 MiB/s
done
Bytes transferred = 412460 (64b2c hex)
SF: Detected w25q128 with page size 256 Bytes, erase size 4 KiB, total 16 MiB
device 0 offset 0x20000, size 0x64b2c
SF: 412460 bytes @ 0x20000 Written: OK

In order to store the serverip and the DHCP or otherwise assigned IP address of the board and have them available on next boot, you can run the following command:

=> saveenv
Saving Environment to SPIFlash... Erasing SPI flash...Writing to SPI flash...done
OK

At this point the U-Boot binary is stored in flash. You can now disconnect the ICE-1000 or ICE-2000 from the development board and make sure to switch the BMODE to position 1. You will only need to reconnect this if your board fails to boot and you need to re-follow these instructions.