USBH device tree configuration

Article purpose

本文介绍如何在将 USBH internal peripheral 分配给 Linux^® 操作系统时对其进行配置。 在这种情况下，它由USB framework控制。

使用device tree机制执行配置。

“ USBH Linux驱动程序” (EHCI, OHCI) ，它们在USB framework中注册了相关信息。

DT bindings documentation

STM32 USBH internal peripheral 是一个USB主机设备，由EHCI控制器和OHCI控制器组成。 每个控制器代表一个单独的绑定文档：

• 通用USB EHCI控制器设备树绑定 d文档处理标准EHCI控制器核心资源（例如寄存器，时钟，重置，中断等）。
• 通用USB OHCI控制器设备树绑定 文档处理标准OHCI控制器核心资源（例如寄存器，时钟，复位，中断等）。

每个控制器使用USB framework提出的通用USB主机控制器设备（HCD）属性和通用USB属性：

• 通用USB HCD设备树绑定 文档处理USB主机控制器PHY资源。
• 通用USB设备树绑定 通用USB设备树绑定文档涉及USB可选属性(例如，最大速度、同伴等)。

DT configuration

该硬件描述是“STM32微处理器”设备树文件（扩展名为.dtsi）和“板子”设备树文件（扩展名为.dts）的组合。 有关设备树文件分割的说明，请参见 Device tree。

STM32CubeMX可用于生成板卡设备树。 有关更多详细信息，请参考 How to configure the DT using STM32CubeMX。

DT configuration (STM32 level)

在stm32mp157c.dtsi中声明。

它们由一组属性组成，用于描述 USBH_EHCI and USBH_OHCI 控制器：寄存器地址，时钟，复位，中断...

usbh_ohci: usbh-ohci@5800c000 { 			/* USBH OHCI controller */
	compatible = "generic-ohci";
	reg = <0x5800c000 0x1000>;
	clocks = <&rcc USBH>;
	resets = <&rcc USBH_R>;
	interrupts = <GIC_SPI 74 IRQ_TYPE_LEVEL_HIGH>;
	status = "disabled";
};

usbh_ehci: usbh-ehci@5800d000 { 			/* USBH EHCI controller */
	compatible = "generic-ehci";
	reg = <0x5800d000 0x1000>;
	clocks = <&rcc USBH>;
	resets = <&rcc USBH_R>;
	interrupts = <GIC_SPI 75 IRQ_TYPE_LEVEL_HIGH>;
	companion = <&usbh_ohci>;  			/* When USBH EHCI controller detects a full or low speed device on a port,
	status = "disabled";  				 * that port is switched over to the USBH OHCI companion controller */
};

该设备树部分与STM32微处理器有关。 它必须保持原样，而不能由最终用户修改。

DT configuration (board level)

请按照以下章节中描述的顺序在板上配置和启用USBH。

USBH 使用片上USBPHYC最多支持两个物理端口：

• USBPHYC port#1 is assigned to the USBH
• USBPHYC port#2 can be statically assigned to the USBH or to the OTG

请参考USBPHYC device tree configuration for additional information on the USBPHYC configuration

USBH由EHCI和OHCI控制器组成：

• 通过EHCI控制器实现高速运行
• 全速和低速操作可以通过以下任一方式实现：
  • 连接到下游端口的高速HUB IC
  • OHCI控制器

DT configuration with external high speed-HUB

• 通过设置status =“ okay”启用usbh_ehci
• 通过phys和phy-names配置PHY

当所有低速和全速流量由直接连接到下游端口的高速集线器管理时，无需启用usbh_ohci。

DT configuration with OHCI to achieve full-speed and low-speed

• 通过设置status =“ okay”启用usbh_ehci
• 通过设置status =“ okay”启用usbh_ohci

对于两个控制器：

• 通过phys和phy-names配置PHY

DT configuration examples

DT configuration when using port0 with a high-speed hub

Below example shows how to configure the USBH when using the physical port 0 (the second physical port is unused).

A high-speed hub controller IC is used on the board: no need to enable usbh_ohci, all low-speed and full-speed traffic is managed by the hub.

&usbh_ehci {
	phys = <&usbphyc_port0>;           /* Use USBPHYC HS PHY port #1, mapped on USBH controller */
	phy-names = "usb";
	status = "okay";
};

/* No need to configure and enable usbh_ohci */

DT configuration when using port0

Below example shows how to configure the USBH when using the physical port 0 (the second physical port is unused, or in use by the OTG and no high-speed hub is used).

&usbh_ehci {
	phys = <&usbphyc_port0>;           /* Use USBPHYC HS PHY port #1, mapped on USBH controller */
	phy-names = "usb";
	status = "okay";
};

&usbh_ohci {
	phys = <&usbphyc_port0>;           /* Use USBPHYC HS PHY port #1, mapped on USBH controller */
	phy-names = "usb";
	status = "okay";
};

DT configuration when using the two physical ports

Below example shows how to configure the USBH when using the two physical ports.

&usbh_ehci {
	phys = <&usbphyc_port0>, <&usbphyc_port1 1>;     /* Use USBPHYC HS PHY port #1, mapped on USBH controller */
                                                         /* Use USBPHYC HS PHY port #2, configure UTMI switch to select USBH controller */
	phy-names = "usb", "usb";
	status = "okay";
};

&usbh_ohci {
	phys = <&usbphyc_port0>, <&usbphyc_port1 1>;     /* Use USBPHYC HS PHY port #1, mapped on USBH controller */
                                                         /* Use USBPHYC HS PHY port #2, configure UTMI switch to select USBH controller */
	phy-names = "usb", "usb";
	status = "okay";
};

How to configure the DT using STM32CubeMX

The STM32CubeMX tool can be used to configure the STM32MPU device and get the corresponding platform configuration device tree files.
The STM32CubeMX may not support all the properties described in the above DT bindings documentation paragraph. If so, the tool inserts user sections in the generated device tree. These sections can then be edited to add some properties and they are preserved from one generation to another. Refer to STM32CubeMX user manual for further information.

References

Please refer to the following links for full description:

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