/dev/uhs

/dev/uhs is the IOSU device node for the USB Host Stack (UHS). 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_ANY             0x000
#define MATCH_DEV_VID         0x001
#define MATCH_DEV_PID         0x002
#define MATCH_DEV_CLASS       0x010
#define MATCH_DEV_SUBCLASS    0x020
#define MATCH_DEV_PROTOCOL    0x040
#define MATCH_IF_CLASS        0x080
#define MATCH_IF_SUBCLASS     0x100
#define MATCH_IF_PROTOCOL     0x200

/* Input buffer */
typedef struct
{
    uint16_t match_params;    /* Bitmask of above flags */
    uint16_t vid, pid;        /* Vendor ID and product ID */
    char unknown6[0xa - 0x6];
    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;

/* Output buffer */
typedef struct
{
    char unknown0[0x30 - 0x0];
    uint16_t vid, pid;
    char unknown34[0x48 - 0x34];
    uint8_t class;
    char unknown34[0x16c - 0x49];
} UhsInterfaceDescriptor;