Build Raspberry Pi 5 Linux Kernel with W5500 Support

Overview

This guide walks you through building and customizing the Linux kernel for the Raspberry Pi 5, including support for the WIZnet W5500 Ethernet module via the WIZ850io. This setup uses Windows with WSL 2 as the development environment and covers kernel modifications, hardware setup, and essential debugging steps.

Development Environment

Target Device: Raspberry Pi 5
Ethernet Module: WIZnet WIZ850io
Host Machine: Windows with WSL 2
Kernel Source: Raspberry Pi Linux Kernel Source

Hardware Setup

Connect the Raspberry Pi 5 to the WIZ850io module as follows:

Raspberry Pi 5	WIZ850io
6 (GND)	GND
1 (3.3V)	3.3V
23 (SPI0_SCLK)	SCLK
19 (SPI0_MOSI)	MOSI
21 (SPI0_MISO)	MISO
18 (BCM24)	RSTn
22 (BCM25)	INTn
24 (SPI0_CE0)	SCn

Refer to the image below for an example of the wiring:

The kernel overlay configuration for the W5500 Ethernet module is as follows. This allows setting the INT pin, SPI speed, and chip select (CS) pin parameters as needed.

Refer to the official Kernel Overlay README for additional details.

Name:   w5500
Info:   Overlay for the Wiznet W5500 Ethernet Controller on SPI0
Load:   dtoverlay=w5500,<param>=<val>
Params: int_pin    GPIO used for INT (default 25)
        speed      SPI bus speed (default 30000000)
        cs         SPI bus Chip Select (default 0)

Kernel and Driver Source Modifications

To monitor the operation of key functions within the Linux kernel and the W5500 driver, debug messages were added, and some sections were modified.

An alignment error in the receive buffer was encountered, which required the following modification. The root cause of this issue is still under investigation:

Regarding the SPI DMA Buffer, the modified parts are as follows.(w5100.c)

..................................
struct w5100_priv {
	const struct w5100_ops *ops;

	/* Socket 0 register offset address */
	u32 s0_regs;
	/* Socket 0 TX buffer offset address and size */
	u32 s0_tx_buf;
	u16 s0_tx_buf_size;
	/* Socket 0 RX buffer offset address and size */
	u32 s0_rx_buf;
	u16 s0_rx_buf_size;

	int irq;
	int link_irq;
	int link_gpio;

	struct napi_struct napi;
	struct net_device *ndev;
	bool promisc;
	u32 msg_enable;

	struct workqueue_struct *xfer_wq;
	struct work_struct rx_work;
	struct sk_buff *tx_skb;
	struct work_struct tx_work;
	struct work_struct setrx_work;
	struct work_struct restart_work;

	// sekim 20241015 add thread for Link
	struct task_struct *monitor_thread; 
	
	// sekim XXXXXX 20241104 DMA Buffer Alignment Issue
	u8 spi_transfer_buf[SPI_TRANSFER_BUF_LEN];
};
..................................

static int w5100_readbulk(struct w5100_priv *priv, u32 addr, u8 *buf, int len)
{
	///////////////////////////////////////////////////////////////////////////
	// sekim XXXXXX 20241104 DMA Buffer Alignment Issue
	//return priv->ops->readbulk(priv->ndev, addr, buf, len);
	{
		int ret;
		if ( len>MAX_FRAMELEN )
		{
			printk("W5K : w5100_readbulk  RRRRR         : len(%4d) align(%d) addr(0x%08x)  ====> Error\n", len, (int)((uintptr_t)buf % 4), (unsigned int)(uintptr_t)buf);
			return -ENOMEM;
		}
		printk("W5K : w5100_readbulk  RRRRR         : len(%4d) align(%d) addr(0x%08x ===> 0x%08x) \n", len, (int)((uintptr_t)buf % 4), (unsigned int)(uintptr_t)buf, (unsigned int)(uintptr_t)priv->spi_transfer_buf);
		ret = priv->ops->readbulk(priv->ndev, addr, priv->spi_transfer_buf, len);
		memcpy(buf, priv->spi_transfer_buf, len);
		return ret;
	}
	///////////////////////////////////////////////////////////////////////////
}

static int w5100_writebulk(struct w5100_priv *priv, u32 addr, const u8 *buf, int len)
{
	///////////////////////////////////////////////////////////////////////////
	// sekim XXXXXX 20241104 DMA Buffer Alignment Issue
	//return priv->ops->writebulk(priv->ndev, addr, buf, len);
	{
		if ( len>MAX_FRAMELEN )
		{
			printk("W5K : w5100_writebulk TTTTT         : len(%4d) align(%d) addr(0x%08x)  ====> Error\n", len, (int)((uintptr_t)buf % 4), (unsigned int)(uintptr_t)buf);
			return -ENOMEM;
		}
		printk("W5K : w5100_writebulk TTTTT         : len(%4d) align(%d) addr(0x%08x ===> 0x%08x) \n", len, (int)((uintptr_t)buf % 4), (unsigned int)(uintptr_t)buf, (unsigned int)(uintptr_t)priv->spi_transfer_buf);
		memcpy(priv->spi_transfer_buf, buf, len);
		return priv->ops->writebulk(priv->ndev, addr, priv->spi_transfer_buf, len);
	}
	///////////////////////////////////////////////////////////////////////////
}
..................................

This part was referenced from enc28j60's source. (enc28j60.c)

struct enc28j60_net {
	struct net_device *netdev;
	struct spi_device *spi;
	struct mutex lock;
	struct sk_buff *tx_skb;
	struct work_struct tx_work;
	struct work_struct setrx_work;
	struct work_struct restart_work;
	u8 bank;		/* current register bank selected */
	u16 next_pk_ptr;	/* next packet pointer within FIFO */
	u16 max_pk_counter;	/* statistics: max packet counter */
	u16 tx_retry_count;
	bool hw_enable;
	bool full_duplex;
	int rxfilter;
	u32 msg_enable;
	u8 spi_transfer_buf[SPI_TRANSFER_BUF_LEN];
};

A dedicated thread was implemented to monitor the Ethernet link status of the W5500 in real-time. This thread checks the link state periodically and logs status changes, such as when the link goes up or down.

// sekim 20241015 add thread for Link
static int w5100_monitor_thread(void *data)
{
    struct w5100_priv *priv = (struct w5100_priv *)data;
    ................

    while (!kthread_should_stop()) 
    {  
        ..............
        if ( old_check_link!=now_check_link )
        {
            if ( now_check_link==1)
            {
                 printk(KERN_INFO "W5K : W5x00 Link Up\n");
                 ...................
            }
            else
            {
                 printk(KERN_INFO "W5K : W5x00 Link Down\n");
                 ...................
            }
        .................

After applying this monitoring thread, if you disconnect and reconnect the Ethernet port, you should see debug messages similar to the following:

To assign a specific MAC address to the W5500, modify the W5500 overlay file as shown below. This customization allows control over the MAC address, which can be useful for network identification and management.

Preparing a USB Drive

To enable easy swapping, a USB stick is used instead of an SD card. The following steps outline how to set up the Raspberry Pi OS on a USB drive.

Download and install Raspberry Pi Imager.
Insert the USB drive into your computer.
Open Raspberry Pi Imager, select the latest version of Raspberry Pi OS, and choose the USB drive as the destination.
Start the installation process and wait until it completes.

This setup allows the Raspberry Pi to boot from the USB drive, making it easier to access and modify files without the need for an SD card.

To access the USB drive within WSL (Windows Subsystem for Linux), follow these steps to mount it correctly:

(DOS) usbipd list
(DOS) usbipd attach --wsl --busid 11-4

lsblk
sudo mount /dev/sdd1 mnt/boot; sudo mount /dev/sdd2 mnt/root

sudo umount mnt/boot; sudo umount mnt/root

To enable USB boot on the Raspberry Pi 5, add usb_max_current_enable=1 and the w5500 overlay to the config.txt file. (This task requires mounting the USB drive first.)

sudo nano mnt/boot/config.txt

To remove unnecessary splash screens and improve the natural behavior of the mouse, I added "usbhid.mousepoll=0" and removed "splash".

sudo nano mnt/boot/cmdline.txt

Build Kernel

Refer to the following link for Raspberry Pi kernel compilation: https://www.raspberrypi.com/documentation/computers/linux_kernel.html

Set the default configuration when building the kernel.

KERNEL=kernel_2712
make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- bcm2712_defconfig

Now, build the kernel and back up and copy files like the kernel and device tree files to the mounted USB drive.
Before proceeding with the steps below, you need to mount the USB drive in WSL.

sudo mount /dev/sdd1 mnt/boot; sudo mount /dev/sdd2 mnt/root

sudo make menuconfig

sudo make -j$(nproc) ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- Image modules dtbs

sudo make -j$(nproc) ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- INSTALL_MOD_PATH=mnt/root modules_install
sudo cp mnt/boot/$KERNEL.img mnt/boot/$KERNEL-backup.img
sudo cp arch/arm64/boot/Image mnt/boot/$KERNEL.img
sudo cp arch/arm64/boot/dts/broadcom/*.dtb mnt/boot/
sudo cp arch/arm64/boot/dts/overlays/*.dtb* mnt/boot/overlays/
sudo cp arch/arm64/boot/dts/overlays/README mnt/boot/overlays/
sudo umount mnt/boot; sudo umount mnt/root

Checking Boot Messages

After completing all the steps, insert the USB drive into the Raspberry Pi and boot it up. In the log below, you can check that the W5500 is recognized and initialized correctly during the boot process.

ssekim@raspberrypi:~ $ dmesg | grep W5K
[    0.000000] W5K : start_kernel()
[    9.261926] W5K : w5100_spi_probe
[    9.261936] W5K : w5100_probe (irq:171, link_gpio:-22)
[    9.265813] W5K : w5500_spi_init()
[    9.265820] W5K : w5100_hw_reset()
[    9.271024] W5K : w5500_memory_configure()
[    9.272864] W5K : W5x00 Link Up
[    9.322150] W5K : w5100_get_drvinfo()
[   13.795703] W5K : w5100_get_drvinfo()
[   13.795810] W5K : w5100_get_drvinfo()
[   14.410316] W5K : w5100_get_drvinfo()
[   14.414438] W5K : w5100_open()
[   14.414446] W5K : w5100_hw_start()
[   14.415222] W5K : w5100_get_link()
[   14.463926] W5K : w5100_get_link()

IP Configuration and Testing

Use the following command to set a static IP on the eth1 interface.

sudo ip addr add 192.168.11.17/24 dev eth1

If you want the settings to persist after a reboot, use the following command.

nmcli connection show
sudo nmcli connection modify be76cf51-6064-3d37-b026-9250d47ea478 ipv4.addresses "192.168.11.17/24" ipv4.gateway "192.168.11.1" ipv4.dns "8.8.8.8" ipv4.method "manual"

※ Appendix A: iPerf Test

Below is the result of the test conducted with iPerf.

※ Appendix B: SPI Low-Level Test

Below is the content of a low-level SPI communication test with the W5500.
It includes an example of a command to read the MAC Address of the W5500 and an SPI signal screen. C source file(w5x00_spi_test.c) is compiled on R-Pi 5.

※ Appendix C: Reload SPI module

Using the following process, you can reset the W5100 driver and SPI module, and restart W5500-related operations.

Check the current W5500 driver status in the kernel.

lsmod | grep w5

Remove the W5100-related SPI module from the kernel using the modprobe command.

sudo modprobe -r w5100-spi; sudo modprobe -r w5100

Reload the SPI module to add it back to the kernel.

sudo modprobe w5100; sudo modprobe w5100-spi

※ Appendix D: Additional useful commands for testing

usbipd list
usbipd attach --wsl --busid 11-4
usbipd detach --busid 11-4

ls -al /lib/modules/$(uname -r)/kernel/drivers/net/ethernet/wiznet/

lsmod | grep w5
sudo modprobe -r w5100-spi; sudo modprobe -r w5100
sudo modprobe w5100; sudo modprobe w5100-spi
lsmod | grep w5

ls /boot/overlays/ | grep w5
sudo dtoverlay -h w5500
sudo dtoverlay w5500
sudo dtoverlay w5500 int_pin=25 speed=500000
sudo dtoverlay -l
sudo dtoverlay -r 0

sudo raspi-config

Name		Name	Last commit message	Last commit date
Latest commit History 30 Commits
Documentation		Documentation
LICENSES		LICENSES
arch		arch
block		block
certs		certs
crypto		crypto
drivers		drivers
fs		fs
include		include
init		init
io_uring		io_uring
ipc		ipc
kernel		kernel
lib		lib
mm		mm
net		net
rust		rust
samples		samples
scripts		scripts
security		security
sound		sound
tools		tools
usr		usr
virt		virt
w5x00work		w5x00work
.clang-format		.clang-format
.cocciconfig		.cocciconfig
.get_maintainer.ignore		.get_maintainer.ignore
.gitignore		.gitignore
.mailmap		.mailmap
.rustfmt.toml		.rustfmt.toml
COPYING		COPYING
CREDITS		CREDITS
Kbuild		Kbuild
Kconfig		Kconfig
MAINTAINERS		MAINTAINERS
Makefile		Makefile
README		README
README.md		README.md
StreamTest.md		StreamTest.md

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Build Raspberry Pi 5 Linux Kernel with W5500 Support

Overview

Development Environment

Hardware Setup

Kernel and Driver Source Modifications

Preparing a USB Drive

Build Kernel

Checking Boot Messages

IP Configuration and Testing

※ Appendix A: iPerf Test

※ Appendix B: SPI Low-Level Test

※ Appendix C: Reload SPI module

※ Appendix D: Additional useful commands for testing

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SteveSEK/rpi5-w5500

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Build Raspberry Pi 5 Linux Kernel with W5500 Support

Overview

Development Environment

Hardware Setup

Kernel and Driver Source Modifications

Preparing a USB Drive

Build Kernel

Checking Boot Messages

IP Configuration and Testing

※ Appendix A: iPerf Test

※ Appendix B: SPI Low-Level Test

※ Appendix C: Reload SPI module

※ Appendix D: Additional useful commands for testing

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