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SolidRun-BMC

This is a BMC (Baseboard Management Controller) Implementation for the SolidRun ARM servers HoneyComb and ClearFog Management Controllers.

The generic version firmware, using a NUCLEO-F042K6, can be found in a seperate repo STM32-BMC

The pin assignment for the SolidRun BMC is as follows:

STM32F042K4u6 Pinout

Here is some table, designating the Signals, the Pin and their function in this project.

Signal Name Pin Default IO Type Description
USB_DP PA12 - SF USB Data +
USB_DM PA11 - SF USB Data -
POWER_BUTTON PB5 HIGH OD Connected in parallel to the Power Button (pulls down to GND when active)
MASTER_RESET PB4 HIGH OD Connected in parallel to the Reset Button (pulls down to GND when active)
VBAT_CONNECTED PB3 HIGH PP Switches the connection from battery to RTC on or off (could clear the boards NVM ?)
FORCE_RECOVERY_REBOOT PA15 HIGH OD Will instruct the board to start the recovery image (maybe parallel to a jumper, pulls down to GND when active)
SPI_MUX PB2 LOW PP Switches the SPI-Flash from Main Processor to Mgmt MCU to access it e.g., for Firmware update
UART1_TX PA9 - SF This is the TX of a UART1 that could be the forwarded to the USB CDC 1 endpoint
UART1_RX PA10 - SF This is the RX of a UART1 that could be the forwarded to the USB CDC 1 endpoint
VCP_TX PA2 - SF This is the TX of a UART2 that could be the forwarded to the USB CDC 2 endpoint
VCP_RX PA3 - SF This is the RX of a UART2 that could be the forwarded to the USB CDC 2 endpoint
ADC_VOLTS PB0 - AI This is the voltage sensing input (not used on Nucleo) The relation is 100 LSB / 1 V (0.01)
ADC_AMPS PB1 - AI This is the current sensing input (not used on Nucleo) The relation is 155 LSB / 1 A (0.00645)

The IO Types are as follows:

  • SF -> Special Function
  • OD -> Open Drain (external Pull-Up)
  • PP -> Push-Pull
  • AI -> Analog Input (connected to an ADC-Channel)

Main functionality

The main purpose of the BMC is to control basic board functions remotely. Therefore, you need to connect the USB to some master control unit. The easiest way to control it is simply using a serial termial e.g., screen /dev/ttyACM1 115200 (if connected on ttyACM1).

The commands are dead simple and single char only (defined in Core/Src/user.c):

Char Function
R Activate reset signal (= pushing the reset button)
r Release reset signal (= releasing the reset button)
P Activate power signal (= pushing the power button)
p Release power signal (= releasing the power button)
B Activate recovery boot signal (= setting a jumper ???)
b Release recovery boot signal (= releasing a jumper ???)
a Get the analog values (optional, can be switched of in main.h FEATURE_ANALOG)

If you issue a command, the controller will respond with Command: OK if it was succesful and with Command: FAIL if not. Usually there can not much go wrong :-) For ADC, it currently reports Measurement: NIY OK meaning Not-Implemented-Yet.

An example program on the host could look like the following(untested) e.g., to reset the ARM server:

$ ./tool R /dev/ttyACM1   # --> the server will go to reset
$ # Wait for a second
$ ./tool r /dev/ttyACM1   # --> The server will come out of reset

...in Python:

import sys
import serial
import time

def main():
    if len(sys.argv) != 3:
        print(f"Usage: {sys.argv[0]} <character> <serial_port>")
        sys.exit(1)

    ch = sys.argv[1]
    serial_port = sys.argv[2]

    ser = serial.Serial(serial_port, 115200, timeout=5)

    ser.write(ch.encode())

    response = ser.readline().decode().strip()

    if "OK" in response:
        print(f"Received OK: {response}")
        ser.close()
        sys.exit(0)
    else:
        print(f"Did not receive OK: {response}")
        ser.close()
        sys.exit(1)

if __name__ == "__main__":
    main()

...in bash

#!/bin/bash

if [ "$#" -ne 2 ]; then
    echo "Usage: $0 <character> <serial_port>"
    exit 1
fi

character="$1"
serial_port="$2"

stty -F "$serial_port" 115200

echo -n "$character" > "$serial_port"

response=$(head -n 1 < "$serial_port")

if [[ "$response" == *"OK"* ]]; then
    echo "Received OK: $response"
    exit 0
else
    echo "Did not receive OK: $response"
    exit 1
fi

...in C:

#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <termios.h>
#include <unistd.h>

int configure_serial_port(int fd) {
    struct termios tty;

    if (tcgetattr(fd, &tty) != 0) {
        perror("tcgetattr");
        return -1;
    }

    cfsetospeed(&tty, B115200);
    cfsetispeed(&tty, B115200);

    tty.c_cflag |= (CLOCAL | CREAD);
    tty.c_cflag &= ~PARENB;
    tty.c_cflag &= ~CSTOPB;
    tty.c_cflag &= ~CSIZE;
    tty.c_cflag |= CS8;

    tty.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
    tty.c_iflag &= ~(IXON | IXOFF | IXANY);

    tty.c_cc[VMIN] = 1;
    tty.c_cc[VTIME] = 5;

    if (tcsetattr(fd, TCSANOW, &tty) != 0) {
        perror("tcsetattr");
        return -1;
    }

    return 0;
}

int main(int argc, char *argv[]) {
    if (argc != 3) {
        printf("Usage: %s <character> <serial_port>\n", argv[0]);
        return 1;
    }

    char ch = argv[1][0];
    char *serial_port = argv[2];

    int fd = open(serial_port, O_RDWR | O_NOCTTY | O_SYNC);
    if (fd < 0) {
        perror("open");
        return 1;
    }

    if (configure_serial_port(fd) < 0) {
        close(fd);
        return 1;
    }

    if (write(fd, &ch, 1) != 1) {
        perror("write");
        close(fd);
        return 1;
    }

    char response[128];
    ssize_t bytes_read = read(fd, response, sizeof(response) - 1);
    if (bytes_read < 0) {
        perror("read");
        close(fd);
        return 1;
    }
    response[bytes_read] = '\0';

    if (strstr(response, "OK") != NULL) {
        printf("Received OK: %s\n", response);
        close(fd);
        return 0;
    } else {
        printf("Did not receive OK: %s\n", response);
        close(fd);
        return 1;
    }
}

Installing the firmware

Prerequisites:

Somehow, STM32CubeProgrammer is not able useing DFU to install the firmware. It is complaining about some readout protection. Fortunately, dfu-util will to the trick and is usually available from the standard package repo of your linux distro. But also compiling it yourself is not the hardest task.

First is to compile the STM32 project (in Release mode), then

# to convert the elf to a dfu file
$ elf2dfuse SolidRun-BMC.elf SolidRun-BMC.dfu

# To flash the firmware to the BMC MCU (the Jumper J5017 must be set)
$ sudo dfu-util -D SolidRun.dfu

# To get from USB Bootloader to the firmware (e.g. after a power outtage)
$ sudo dfu-util  -a 0 -s 0x08000000:leave

ToDos and features

  • Impelement a reset function to boot into Bootloader from Application
  • Do not depend on J5017 anymore to do firmware upgrades (this is usually populated)
  • Add a watchdog
  • Clean up sources to free a bit of memory for additional function
  • Fix the analog readout of voltage and current :-)

Full Installation sequence

  1. When you have your dfu file and dfu-utils available, plug in your USB cable into MGMT of the ARM server
  2. Execute dmesg to see, if the ST Bootloader responds
[ 3402.601630] usb 2-1.1.2.5: new full-speed USB device number 45 using ci_hdrc
[ 3402.700309] usb 2-1.1.2.5: New USB device found, idVendor=0483, idProduct=df11
[ 3402.707643] usb 2-1.1.2.5: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 3402.715434] usb 2-1.1.2.5: Product: STM32  BOOTLOADER
[ 3402.720615] usb 2-1.1.2.5: Manufacturer: STMicroelectronics
[ 3402.726298] usb 2-1.1.2.5: SerialNumber: FFFFFFFEFFFF

First check, if the STM32 is recognized by dfu-util

sudo src/dfu-util -l

dfu-util 0.11-dev

Copyright 2005-2009 Weston Schmidt, Harald Welte and OpenMoko Inc.
Copyright 2010-2021 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=2200, devnum=22, cfg=1, intf=0, path="2-1.1.2.2", alt=0, name="@Internal Flash  /0x08000000/032*0001Kg", serial="FFFFFFFEFFFF"
Found DFU: [0483:df11] ver=2200, devnum=22, cfg=1, intf=0, path="2-1.1.2.2", alt=1, name="@Option Bytes  /0x1FFFF800/01*016 e", serial="FFFFFFFEFFFF"

Download the firmware to the STM32 using dfu-util (from the dfu-util GIT repo with the binary compiled in src)

sudo src/dfu-util -d 0483:df11 -a 0 -D /home/glada/SolidRun-BMC.dfu

Your output should look something like this

dfu-util 0.11-dev

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/

Opening DFU capable USB device...
ID 0483:df11
Run-time device DFU version 011a
Claiming USB DFU Interface...
Setting Alternate Setting #0 ...
Determining device status: state = dfuERROR, status = 10
dfuERROR, clearing status
Determining device status: state = dfuIDLE, status = 0
dfuIDLE, continuing
DFU mode device DFU version 011a
Device returned transfer size 2048
DfuSe interface name: "Internal Flash  "
file contains 1 DFU images
parsing DFU image 1
image for alternate setting 0, (1 elements, total size = 15760)
parsing element 1, address = 0x08000000, size = 15752
Download        [=========================] 100%        15752 bytes
Download done.
done parsing DfuSe file

Then instruct the STM32 to jump into application:

sudo src/dfu-util -d 0483:df11 -a 0 -s 0x08000000:leave

[ 3418.036324] usb 2-1.1.2.5: USB disconnect, device number 45
[ 3418.234911] usb 2-1.1.2.5: new full-speed USB device number 46 using ci_hdrc
[ 3418.334561] usb 2-1.1.2.5: New USB device found, idVendor=0483, idProduct=5740
[ 3418.341902] usb 2-1.1.2.5: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 3418.349682] usb 2-1.1.2.5: Product: SolidRun BMC
[ 3418.354400] usb 2-1.1.2.5: Manufacturer: STMicroelectronics
[ 3418.360076] usb 2-1.1.2.5: SerialNumber: 203930515252
[ 3418.370435] cdc_acm 2-1.1.2.5:1.0: ttyACM7: USB ACM device

This tells you, that /dev/ttyACM7 is your route to the MGMT interface.

Copy the SerialNumber from dmesg output and paste it into a udev-rule to make the MGMT device get a unique name for this ARM server e.g., in /etc/udev/rules.d/99-solidrun-mgmt.rules.

    SUBSYSTEM=="tty", SUBSYSTEMS=="usb", DRIVERS=="usb", ATTRS{serial}=="203930515252", SYMLINK+="ttyMGMT-tux42"

After triggering udev using the command udevadm trigger, you should see your symlinked device /dev/ttyMGMT-tux42 linked to /dev/ttyACM7 (in the example above).

If you now connect to this serial interface (e.g., using screen /dev/ttyMGMT-tux42 115200), you can issue a reset by pressing R and then r in the screen session console. Exit your screen with CTRL+A D. See your screen sessions with screen -ls and reattaching with screen -r <PROCID>. If it does not work, have a look, if you have the correct rights to access the real device (/dev/ttyACM7). Usually this is the group dialout.