x86架构Up Board 2（Ubilinux）下如何定义MPC2515 SPI设备设置？

Got it, since you're working on an x86-based Up Board 2 where device trees aren't used (unlike ARM systems), we need to rely on kernel modules and sysfs/module parameters to register the MCP2515 SPI device. Here's a step-by-step guide:

1. Verify & Load Required Kernel Modules #

First, make sure the SPI controller driver and MCP2515 CAN driver are available:

• Check if the SPI controller module is loaded (for Apollo Lake-based Up Board 2, this is usually spi_intel):

  lsmod | grep spi
  

• Check if the MCP2515 driver is loaded:

  lsmod | grep mcp251x
  

• If either module is missing, load them manually:

  modprobe spi_intel
  modprobe mcp251x
  

• If modules don't exist at all, you'll need to recompile your kernel with these configs enabled:
  • CONFIG_SPI_INTEL=m or =y (for Intel SPI controller)
  • CONFIG_CAN_MCP251X=m or =y (for MCP2515 CAN driver)

2. Register the MCP2515 SPI Device #

Since there's no device tree, we have to manually tell the kernel about the MCP2515 on the SPI bus. Use one of these two methods:

Method 1: Sysfs Interface (Recommended) #

This is the most flexible way to register the device at runtime:

• First, identify your SPI bus number (Up Board typically uses spi0; confirm with ls /sys/bus/spi/devices/).
• Register the MCP2515 with your SPI bus and chip select (CS) pin (replace spi0 and 0 with your actual bus/CS number):

  echo mcp2515 0 > /sys/bus/spi/devices/spi0/new_device
  

  • The 0 here is the chip select pin number (adjust if you're using a different CS pin).

Method 2: Module Parameters #

You can pass device details directly when loading the MCP2515 driver:

• Unload the driver first if it's already loaded:

  rmmod mcp251x
  

• Reload the driver with SPI bus, CS, and speed parameters (adjust values to match your hardware):

  modprobe mcp251x spi_port=0 spi_cs=0 spi_speed=1000000
  

  • spi_speed sets the SPI clock (MCP2515 supports up to 10MHz; 1MHz is a safe default).

3. Configure & Activate the CAN Interface #

Once the device is registered, the kernel will create a CAN interface (usually can0):

• List available CAN interfaces to confirm:

  ip link show
  

• Set your desired CAN bitrate (e.g., 500kbps):

  ip link set can0 type can bitrate 500000
  

• Activate the interface:

  ip link set can0 up
  

• Test the interface:
  • Send a test frame:

    cansend can0 123#1122334455667788
    

  • Listen for incoming frames:

    candump can0
    

4. Persist Settings Across Reboots #

To make these changes stick after a reboot:

1. Add the required modules to /etc/modules so they load on boot:

   spi_intel
   mcp251x
   

2. Create a systemd service to auto-register the device and configure the CAN interface:
   • Create /etc/systemd/system/can-setup.service with this content:

     [Unit]
     Description=Auto-configure MCP2515 CAN Interface
     After=multi-user.target
     
     [Service]
     Type=oneshot
     ExecStart=/bin/bash -c 'echo mcp2515 0 > /sys/bus/spi/devices/spi0/new_device; ip link set can0 type can bitrate 500000; ip link set can0 up'
     
     [Install]
     WantedBy=multi-user.target
     

   • Enable and start the service:

     systemctl enable can-setup.service
     systemctl start can-setup.service
     

Important Hardware Notes #

Double-check your wiring:

• Connect SPI SCLK, MOSI, MISO pins between Up Board and MCP2515 correctly.
• Ensure the CS pin matches the chip select number you used in the registration step.
• The MCP2515's INT pin can be connected to a GPIO for interrupt support (optional but improves performance), but it's not required for basic functionality.

内容的提问来源于stack exchange，提问作者MaryemAyadi