The STM32MP25 CPU has two USB controllers, both with integrated PHYs:

  • One USB 2.0 host high-speed port.

  • One USB 3.0 DRD port (5 Gbit/s) configurable as host or device. This port can also operate as a second USB 2.0 host high-speed port, thus releasing the super-speed COMBOPHY for the PCIe functionality.

USB interfaces on the ConnectCore MP25

On the ConnectCore MP25 system-on-module both USB ports are available for peripheral use.

On the ConnectCore MP25 Development Kit:

  • USB2H is connected to a four-port USB hub.

  • USB3DR is available at the USB type-C connector.

PCIe PHY (COMBOPHY) is shared with USB3DR controller. Only one protocol can be active at a time.

USB3DR SuperSpeed capability is disabled in the default ConnectCore MP25 Development Kit device tree in favor of PCIe support.

Kernel configuration

You can manage the USB ports support through the kernel configuration options:

  • Support for Host-side USB (CONFIG_USB)

  • DesignWare USB2 DRD Core Support (CONFIG_USB_DWC2)

  • ChipIdea device controller (CONFIG_USB_CHIPIDEA_UDC)

  • DesignWare USB3 DRD Core Support (CONFIG_USB_DWC3)

  • STM32 DWC3 support (CONFIG_USB_DWC3_STM32)

  • STMicroelectronics STM32 USB2 FEMTO PHY Controller driver (CONFIG_PHY_STM32_USB2FEMTO)

All of these kernel configuration options are enabled as built-in on the default ConnectCore MP25 kernel configuration file.

The USB device driver provides the functionality for the USB gadget drivers. The USB gadget drivers implement one or more "functions", each providing a different capability.

The following gadget drivers are supported and enabled as loadable modules on the default ConnectCore MP25 kernel configuration file.

  • Mass Storage Gadget (CONFIG_USB_MASS_STORAGE)

  • Ethernet Gadget with CDC Ethernet support (CONFIG_USB_ETH)

  • Serial Gadget with ACM and CDC OBEX support (CONFIG_USB_G_SERIAL)

Gadget drivers are enabled as loadable modules because only one gadget function can be used at a time. Before using a gadget driver, you must first make sure no other gadget driver is loaded.

Kernel driver

The STM32MP25 universal serial bus (USB) driver implements a standard Linux driver interface to the CHIPIDEA USB controller. The CHIPIDEA USB controller is enhanced host controller interface (EHCI) compliant.

The STM32MP25 USB drivers are located at:

File Description

chipidea/core.c

Chipidea IP core driver

chipidea/udc.c

Chipidea peripheral driver

chipidea/host.c

Chipidea host driver

drivers/phy/st/phy-stm32-usb2femto.c

STMicroelectronics STM32 USB2 FEMTO PHY Controller driver

dwc3/dwc3-stm32.c

DesignWare Core USB3 controller on STM32 SOCs driver

Device tree bindings and customization

The STM32MP25 USB controller device tree bindings are documented at Documentation/devicetree/bindings/usb/ci-hdrc-usb2.txt.

Example: ConnectCore MP25 Development Kit

The USB2H port works as host only. The USB3DR port is configured by default to work as USB 2.0 host.

ConnectCore MP25 Development Kit device tree
/ {
	/* USB 3.0 Data switch */
	usb3_data_switch: cbtl04gp {
		compatible = "nxp,cbtu02043";
		switch-gpios = <&gpiod 11 GPIO_ACTIVE_HIGH>; /* USBC_BUS_SEL */
		shutdown-gpios = <&gpiod 10 GPIO_ACTIVE_LOW>; /* USBC_SW_PWR */
		orientation-switch;
		status = "disabled";

		port {
			typec_ep: endpoint {
				remote-endpoint = <&dwc3_ep>;
			};
		};
	};
};

&combophy {
	clocks = <&rcc CK_BUS_USB3PCIEPHY>, <&rcc CK_KER_USB3PCIEPHY>, <&pad_clk>;
	clock-names = "apb-clk", "ker-clk", "pad-clk";
	status = "okay";
};

/* USB 2.0 Host */
&usb2_phy1 {
	status = "okay";
};

&usb2h {
	status = "okay";
};

&usb2h_ehci {
	status = "okay";
};

/* USB 2.0/3.0 Host/Device */
&usb2_phy2 {
	status = "okay";
};

&usb3dr {
	status = "okay";

	dwc3: usb@48300000 {
		maximum-speed = "high-speed";
		usb-role-switch;

		port {
			dwc3_ep: endpoint {
				remote-endpoint = <&typec_ep>;
			};
		};
	};
};

USB 3.0

The current beta BSP doesn’t support USB 3.0 out-of-box. To use USB3DR as USB 3.0 you have to do the following workaround:

  1. Add the following device tree overlay to U-Boot’s overlays variable:

    => setenv overlays _ov_board_usb-3-0-typec_ccmp25-dvk.dtb,${overlays}
=> saveenv

  2. Initialize the device’s eMMC as a USB mass storage:

    => ums 0 mmc 0
UMS: LUN 0, dev mmc 0, hwpart 0, sector 0x0, count 0xe90e80
dwc3-generic-wrapper usb@48300000: configured in usb2 mode

  3. Press Ctrl+C to abort the operation.

  4. Boot the target

    => boot

USB 3.0 will work out-of-box in the next official release.

USB 3.0 Type-C wire orientation detection is not supported yet; only one side works by default.

Using the USB port

See the following topics for information on how to use the USB port.