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Options for "early" UART access on boot

Steven Hansen
Intellectual 666 points
Part Number: AM6442

Hi TI team,

We are working on a design that uses AM64x and a C2000 DSP on the same board. After Linux boots, we use one of the AM64x UART ports to load firmware to the C2000 DSP. We like this method since it allows the C2000 firmware to be stored on the AM64x eMMC, which is easy to update. However this boot flow takes too long for our application (~15-20 sec for Linux boot on AM64x which delays loading of DSP firmware). We are trying to find a better option that allows us to start loading the C2000 firmware <500ms after POR if possible.

Current method (too slow):

AM64x SPL boot -> U-boot -> Linux boots on A53 -> Linux app reads firmware from eMMC -> Linux app writes firmware to C2000 DSP via UART

Idea for faster DSP load:

Customize SPL to read firmware from eMMC -> SPL loads firmware to C2000 DSP via UART -> SPL branches to U-boot -> Boot Linux on A53s

Questions

1. Is it possible to customize the SPL?

2. Can SPL read the file system on eMMC to find the C2000 firmware (a simple file on eMMC file system)?

3. What is required to enable a UART port in the SPL?

4. If we could create a custom SBL that might be a better option, but as I understand it SBL cannot branch to U-boot SPL as of Processor-SDK v8.00. Is that correct?

5. Is there a better option for "early" access to UART during boot on AM64x?

Thanks!

  • 0
    TI__Guru 68960 points

    Hi Steven,
    You may refer to the link for eMMC partitions on AM64x GP EVM
    software-dl.ti.com/.../UG-Memory.html
    where for default eMMC booting:
    - boot partition is RAW
    - user partition is EXT4

    Reading eMMC to DDR from boot partition or user partition is possible @u-boot prompt.
    I'm attaching a log file I captured on AM64x GP EVM for your reference, where
    - tiboot3.bin is read to DDR from the boot partition
    - k3-am642-evm.dtb is read to DDR from the user partition

    For your questions:
    1. Yes
    2. For eMMC boot, the first bootloader (tiboot3.bin running on R5) can read the next stage bootloaders (tispl.bin running on A53) from the boot partition (RAW for default eMMC boot). After booting to u-boot prompt, reading eMMC to DDR from boot partition (RAW) and user partition (EXT4) is possible as shown in the attached log file.
    3. In default u-boot, it is possible to output to UART port for serial terminal logging, and also to read from UART port to DDR (ie. loadx/loady etc...u-boot cmds...).
    4. The current plan is to enable SBL booting Linux in SDK 8.1 tentatively targeted towards to the end of Nov-2021.
    5. See #3 above.

    Best,

    -Hong

    Fullscreen am6_emmc_read.txt Download 
    U-Boot SPL 2020.01-00016-ge995ed0ec1-dirty (Jul 01 2021 - 17:43:11 -0500)
SYSFW ABI: 3.1 (firmware rev 0x0015 '21.1.1--v2021.01a (Terrific Lla')
SPL initial stack usage: 13396 bytes
Trying to boot from MMC1
Loading Environment from MMC... OK
init_env from device 9 not supported!
Starting ATF on ARM64 core...

NOTICE:  BL31: v2.4(release):2021.00.003-dirty
NOTICE:  BL31: Built : 14:41:43, May 28 2021

U-Boot SPL 2020.01-00016-ge995ed0ec1-dirty (Jul 01 2021 - 17:40:32 -0500)
SYSFW ABI: 3.1 (firmware rev 0x0015 '21.1.1--v2021.01a (Terrific Lla')
Trying to boot from MMC1


U-Boot 2020.01-00016-ge995ed0ec1-dirty (Jul 01 2021 - 17:40:32 -0500)

SoC:   AM64X SR1.0
Model: Texas Instruments AM642 EVM
Board: AM64-GPEVM rev E2
DRAM:  2 GiB
not found for dev mux
MMC:   sdhci@fa10000: 0, sdhci@fa00000: 1
Loading Environment from MMC... OK
In:    serial@2800000
Out:   serial@2800000
Err:   serial@2800000
Net:   
Warning: ethernet@8000000 using MAC address from ROM
eth0: ethernet@8000000
Hit any key to stop autoboot:  2  0 
=> md.b ${loadaddr} 0x100
82000000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
82000010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
82000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
82000030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
82000040: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
82000050: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
82000060: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
82000070: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
82000080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
82000090: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
820000a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
820000b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
820000c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
820000d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
820000e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
820000f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
=> mmc dev 0 1
switch to partitions #1, OK
mmc0(part 1) is current device
=> mmc read ${loadaddr} 0x0 0x100

MMC read: dev # 0, block # 0, count 256 ... 256 blocks read: OK
=> md.b ${loadaddr} 0x100
82000000: 30 82 04 27 30 82 03 90 a0 03 02 01 02 02 09 00    0..'0...........
82000010: b1 c2 22 c5 5a ed 28 b3 30 0d 06 09 2a 86 48 86    ..".Z.(.0...*.H.
82000020: f7 0d 01 01 0d 05 00 30 81 9d 31 0b 30 09 06 03    .......0..1.0...
82000030: 55 04 06 13 02 55 53 31 0b 30 09 06 03 55 04 08    U....US1.0...U..
82000040: 0c 02 54 58 31 0f 30 0d 06 03 55 04 07 0c 06 44    ..TX1.0...U....D
82000050: 61 6c 6c 61 73 31 27 30 25 06 03 55 04 0a 0c 1e    allas1'0%..U....
82000060: 54 65 78 61 73 20 49 6e 73 74 72 75 6d 65 6e 74    Texas Instrument
82000070: 73 20 49 6e 63 6f 72 70 6f 72 61 74 65 64 31 13    s Incorporated1.
82000080: 30 11 06 03 55 04 0b 0c 0a 50 72 6f 63 65 73 73    0...U....Process
82000090: 6f 72 73 31 13 30 11 06 03 55 04 03 0c 0a 54 49    ors1.0...U....TI
820000a0: 20 53 75 70 70 6f 72 74 31 1d 30 1b 06 09 2a 86     Support1.0...*.
820000b0: 48 86 f7 0d 01 09 01 16 0e 73 75 70 70 6f 72 74    H........support
820000c0: 40 74 69 2e 63 6f 6d 30 1e 17 0d 32 31 30 37 30    @ti.com0...21070
820000d0: 31 32 32 34 37 33 38 5a 17 0d 32 31 30 37 33 31    1224738Z..210731
820000e0: 32 32 34 37 33 38 5a 30 81 9d 31 0b 30 09 06 03    224738Z0..1.0...
820000f0: 55 04 06 13 02 55 53 31 0b 30 09 06 03 55 04 08    U....US1.0...U..
=> ls mmc 0
<DIR>       4096 .
<DIR>       4096 ..
<DIR>      16384 lost+found
<DIR>       4096 bin
<DIR>       4096 boot
<DIR>       4096 dev
<DIR>       4096 etc
<DIR>       4096 home
<SYM>         20 init
<DIR>       4096 lib
<SYM>         19 linuxrc
<DIR>       4096 media
<DIR>       4096 mnt
<DIR>       4096 proc
<DIR>       4096 run
<DIR>       4096 sbin
<DIR>       4096 sys
<DIR>       4096 tmp
<DIR>       4096 usr
<DIR>       4096 var
=> ls mmc 0 boot
<DIR>       4096 .
<DIR>       4096 ..
<SYM>         25 Image
        19137024 Image-5.10.41-g4c2eade9f7
            2284 k3-am642-evm-icssg1-dualemac.dtbo
           53223 k3-am642-evm.dtb
           50833 k3-am642-sk.dtb
<SYM>         30 vmlinux.gz
         8993739 vmlinux.gz-5.10.41-g4c2eade9f7
=> load mmc 0 ${loadaddr} /boot/k3-am642-evm.dtb
53223 bytes read in 5 ms (10.2 MiB/s)
=> md.b ${loadaddr} 0x100
82000000: d0 0d fe ed 00 00 cf e7 00 00 00 38 00 00 ba ec    ...........8....
82000010: 00 00 00 28 00 00 00 11 00 00 00 10 00 00 00 00    ...(............
82000020: 00 00 14 fb 00 00 ba b4 00 00 00 00 00 00 00 00    ................
82000030: 00 00 00 00 00 00 00 00 00 00 00 01 00 00 00 00    ................
82000040: 00 00 00 03 00 00 00 1c 00 00 00 00 54 65 78 61    ............Texa
82000050: 73 20 49 6e 73 74 72 75 6d 65 6e 74 73 20 41 4d    s Instruments AM
82000060: 36 34 32 20 45 56 4d 00 00 00 00 03 00 00 00 16    642 EVM.........
82000070: 00 00 00 06 74 69 2c 61 6d 36 34 32 2d 65 76 6d    ....ti,am642-evm
82000080: 00 74 69 2c 61 6d 36 34 32 00 00 00 00 00 00 03    .ti,am642.......
82000090: 00 00 00 04 00 00 00 11 00 00 00 01 00 00 00 03    ................
820000a0: 00 00 00 04 00 00 00 22 00 00 00 02 00 00 00 03    ......."........
820000b0: 00 00 00 04 00 00 00 31 00 00 00 02 00 00 00 01    .......1........
820000c0: 61 6c 69 61 73 65 73 00 00 00 00 03 00 00 00 26    aliases........&
820000d0: 00 00 00 3d 2f 62 75 73 40 66 34 30 30 30 2f 62    ...=/bus@f4000/b
820000e0: 75 73 40 34 30 30 30 30 30 30 2f 73 65 72 69 61    us@4000000/seria
820000f0: 6c 40 34 61 30 30 30 30 30 00 00 00 00 00 00 03    l@4a00000.......
=>

  • 0 in reply to Hong Guan64
    Intellectual 666 points

    Hi Hong,

    Thanks for the feedback. I was able to build a customized SPL, but now that I'm familiar with the process I think a better option is to branch the first R5F core to a custom application after the R5F SPL boots the A53. Something like:

    R5F0_0 => ROM => SPL => load SYSFW => boot A53 => branch to R5F application

    Is this possible on AM64x, and if so are there any examples how to set this up?

  • 0 in reply to Steven Hansen
    TI__Guru 68960 points

    Hi Steven,
    There's a out-of-box benchmark demo in AM64x SDK:
    software-dl.ti.com/.../Benchmark_Demo_User_Guide.html
    software-dl.ti.com/.../EXAMPLE_MOTORCONTROL_BENCHMARKDEMO.html
    Please have a look to see if it helps your design.
    Best,
    -Hong

  • 0 in reply to Hong Guan64
    Intellectual 666 points

    Hi Hong,

    I thought the benchmark demo app uses Linux remoteproc to boot the R5Fs, not SPL or U-boot. Or am I wrong?

    Also, how can I add the benchmark demo to a Yocto build? By default, I only get the Matrixgui app when building tisdk-default-image, the benchmark demo is not included. I am building with coresdk-08.00.00.004.

  • 0 in reply to Steven Hansen
    TI__Guru 68960 points

    Hi Steven,
    Sorry for delayed response as I was out of office for one week.
    Yes, you're right that the benchmark demo app uses Linux rproc to boot the R5Fs.
    Will you be able to build benchmark demo following the links in my last reply?
    Best,
    -Hong