I made this patch with the help of pardis at IRC. This gives support for UGREEN USB to Serial RS-232 based on Prolific PL2303.
Index: uplcom.c =================================================================== RCS file: /cvs/src/sys/dev/usb/uplcom.c,v retrieving revision 1.77 diff -u -p -u -p -r1.77 uplcom.c --- uplcom.c 27 Jan 2021 17:28:19 -0000 1.77 +++ uplcom.c 15 Jun 2021 13:19:22 -0000 @@ -162,6 +162,7 @@ static const struct usb_devno uplcom_dev { USB_VENDOR_PROLIFIC, USB_PRODUCT_PROLIFIC_PL2303GC }, { USB_VENDOR_PROLIFIC, USB_PRODUCT_PROLIFIC_PL2303X }, { USB_VENDOR_PROLIFIC, USB_PRODUCT_PROLIFIC_PL2303X2 }, + { USB_VENDOR_PROLIFIC, USB_PRODUCT_PROLIFIC_PL2303ALB }, { USB_VENDOR_PROLIFIC, USB_PRODUCT_PROLIFIC_RSAQ2 }, { USB_VENDOR_PROLIFIC, USB_PRODUCT_PROLIFIC_PL2303BENQ }, { USB_VENDOR_PROLIFIC2, USB_PRODUCT_PROLIFIC2_PL2303 }, Index: usbdevs.h =================================================================== RCS file: /cvs/src/sys/dev/usb/usbdevs.h,v retrieving revision 1.752 diff -u -p -u -p -r1.752 usbdevs.h --- usbdevs.h 18 May 2021 14:23:53 -0000 1.752 +++ usbdevs.h 15 Jun 2021 13:19:23 -0000 @@ -3656,6 +3656,7 @@ #define USB_PRODUCT_PROLIFIC_PL2501 0x2501 /* PL2501 Host-Host */ #define USB_PRODUCT_PROLIFIC_PL2303X 0xaaa0 /* PL2303 Serial */ #define USB_PRODUCT_PROLIFIC_PL2303X2 0xaaa2 /* PL2303 Serial */ +#define USB_PRODUCT_PROLIFIC_PL2303ALB 0x23c3 /* PL2303 Serial */ /* Prolific(2) products */ #define USB_PRODUCT_PROLIFIC2_PL2303 0x2303 /* PL2303 Serial */