On 12/12/22 11:44, Fabrice Gasnier wrote:
The main issue the driver addresses is that a USB hub needs to be powered before it can be discovered. This is often solved by using "regulator-always-on".
This driver is inspired by the Linux v6.1 driver. It only enables (or disables) the hub vdd (3v3) supply, so it can be enumerated. Scanning of the device tree is done in a similar manner to the sandbox, by the usb-uclass. DT part looks like:
&usbh_ehci { ... #address-cells = <1>; #size-cells = <0>; hub@1 { compatible = "usb424,2514"; reg = <1>; vdd-supply = <&v3v3>; }; };
When the bus gets probed, the driver is automatically probed/removed from the bus tree, as an example on stm32: STM32MP> usb start starting USB... STM32MP> dm tree Class Index Probed Driver Name
usb 0 [ + ] ehci_generic | |-- usb@5800d000 usb_hub 0 [ + ] usb_onboard_hub | | `-- hub@1 usb_hub 1 [ + ] usb_hub | | `-- usb_hub
STM32MP> usb tree USB device tree: 1 Hub (480 Mb/s, 0mA) | u-boot EHCI Host Controller | +-2 Hub (480 Mb/s, 2mA)
Signed-off-by: Fabrice Gasnier fabrice.gasnier@foss.st.com
Reviewed-by: Marek Vasut marex@denx.de