/dev/uhs

/dev/uhs is the IOSU device node for USB. It provides an interface for low-level USB device access, which nsysuhs.rpl exposes to the Cafe OS userspace. The interface is opened through /dev/uhs/%d, where %d is an integer representing something (controller number?). Only 0 can be opened, as 1 returns access denied and further values do not exist as device nodes. Once opened, ioctl() requests can be issued to the interface, which are documented below.

ioctl() interface

0x11 - UhsQueryInterfaces()

This function is used to determine which USB device interfaces are plugged in and available. Its input is a 0x10-byte buffer containing a series of parameters to filter the interfaces by, such as class, subclass, vendor ID, and product ID. The output is an array of 0x16c-byte interface descriptors, one for each interface being read. IOS_Ioctl() with this function returns the number of attached USB interfaces permitted by the filter.

/* Determines which parameters to check */
#define MATCH_DEV_CLASS    0x10
#define MATCH_IF_CLASS     0x80

/* Input buffer */
typedef struct
{
    uint16_t match_params;     /* Bitmask of above flags */
    char unknown2[0xa - 0x2];  /* VID and PID presumably here somewhere */
    uint8_t dev_class;         /* Device class */
    uint8_t dev_subclass;      /* Device subclass */
    uint8_t dev_protocol;      /* Device protocol */
    uint8_t if_class;          /* Interface class */
    uint8_t if_subclass;       /* Interface subclass */
    uint8_t if_protocol;       /* Interface protocol */ 
} UhsInterfaceFilter;