USB services

One symbol in USB-sysmodule is: "vtable for nn::usb::detail::UsbComplexTegra21x".

usb:ds

Used for Switch<>PC USB comms, aka Switch-as-device. This service is used during factory setup by manu.

This service session is used as an IPC domain by manu. All of these {get-session} commands also return an output u8 and the u32 <domainID>, for using those sessions as domains.

Cmd	Name	Notes
0	#BindDevice
1	#BindClientProcess
2	#GetDsInterface
3	#GetStateChangeEvent
4		No input. Returns an output u32.
5	#SetVidPidBcd

Initialization done by manu:

• Initial service init:
  • Get service/etc.
  • Uses #BindDevice.
  • Uses #BindClientProcess.
  • Uses #GetStateChangeEvent.
  • Uses #SetVidPidBcd.
• Interface init:
  • Uses #GetDsInterface, then uses commands from that with the rest of the following.
  • Uses #GetSetupEvent.
  • Uses #GetCtrlInCompletionEvent.
  • Uses #GetCtrlOutCompletionEvent.
• Initializes two endpoints via using #GetDsEndpoint twice.

Configuration

The following is the default USB config strings, while the usbds service isn't being used. All of the below configuration will reset to the defaults when all usbds-related sessions are closed. These can be set with #SetVidPidBcd. The default string for Product is loaded from settings config.

 Product: Nintendo Switch
 Manufacturer: Nintendo
 SerialNumber: SerialNumber

The following is the default lsusb -v {...} output when the usbds service wasn't used.

The endpoints are configured using #GetDsEndpoint, the total number of endpoints is the number of open #IDsEndpoint sessions. bInterfaceNumber is {0-based index for the enabled #IDsInterface session.} Some of the interface fields are configured using #GetDsInterface.

 Bus 003 Device 006: ID 057e:2000 Nintendo Co., Ltd 
 Couldn't open device, some information will be missing
 Device Descriptor:
   bLength                18
   bDescriptorType         1
   bcdUSB               2.00
   bDeviceClass            0 (Defined at Interface level)
   bDeviceSubClass         0 
   bDeviceProtocol         0 
   bMaxPacketSize0        64
   idVendor           0x057e Nintendo Co., Ltd
   idProduct          0x2000 
   bcdDevice            1.00
   iManufacturer           1 
   iProduct                2 
   iSerial                 3 
   bNumConfigurations      1
   Configuration Descriptor:
     bLength                 9
     bDescriptorType         2
     wTotalLength           34
     bNumInterfaces          1
     bConfigurationValue     1
     iConfiguration          0 
     bmAttributes         0xc0
       Self Powered
     MaxPower              {...}
     Interface Descriptor:
       bLength                 9
       bDescriptorType         4
       bInterfaceNumber        0
       bAlternateSetting       0
       bNumEndpoints           1
       bInterfaceClass         3 Human Interface Device
       bInterfaceSubClass      0 No Subclass
       bInterfaceProtocol      0 None
       iInterface              0 
         HID Device Descriptor:
           bLength                 9
           bDescriptorType        33
           bcdHID               2.00
           bCountryCode            0 Not supported
           bNumDescriptors         1
           bDescriptorType        34 Report
           wDescriptorLength      26
          Report Descriptors: 
            ** UNAVAILABLE **
       Endpoint Descriptor:
         bLength                 7
         bDescriptorType         5
         bEndpointAddress     0x81  EP 1 IN
         bmAttributes            3
           Transfer Type            Interrupt
           Synch Type               None
           Usage Type               Data
         wMaxPacketSize     0x0001  1x 1 bytes
         bInterval              16

BindDevice

Takes an u32 (complexId). Manu sends 0x02.

Binding more than once with the current session is not allowed. Once this command is used, the USB device will not be listed with lsusb until #EnableInterface is used.

BindClientProcess

Takes 1 copy-handle for the current process (0xFFFF8001).

GetDsInterface

Takes 2 type-5 buffers and returns an #IDsInterface. Manu sends a 0x09-byte command (e.g.: 0x09, 0x04, 0x04, 0x00, 0x00, 0xFF, 0xFF, 0xFF, 0x00) in the first buffer and a string ("usb") in the second buffer.

When the strlen output for the second buffer is >=0x40, size 0x40 is used instead for copying the string.

Returns an error when #BindDevice wasn't used.

Structure of the first buffer(this is similar to libusb__interface__descriptor):

Offset	Size	Description
0x0	0x1	bLength. Must match 0x9.
0x1	0x1	bDescriptorType. Must match 0x4.
0x2	0x1	When 0x4, an error will be thrown if certain state checks don't pass. Otherwise, this must be <=3.
0x3	0x1	Must match 0x0.
0x4	0x1	?
0x5	0x1	bInterfaceClass
0x6	0x1	bInterfaceSubClass
0x7	0x1	bInterfaceProtocol
0x8	0x1	?

Only the first 0x9-bytes are used.

GetStateChangeEvent

Returns an event handle for state changes.

SetVidPidBcd

Takes a type-5 buffer with 0x66 bytes of USB descriptor data (see manu).

Offset	Size	Description
0x0	0x2	VID (idVendor)
0x2	0x2	PID (idProduct)
0x4	0x2	bcdUSB
0x6	0x20	Manufacturer
0x26	0x20	Product
0x46	0x20	SerialNumber

The last 3 blocks are strings. The data following each string is all-zero, for padding to size 0x20.

IDsInterface

Cmd	Name	Notes
0	#GetDsEndpoint
1	#GetSetupEvent
2		Takes a type-0x6 output buffer, no other output.
3	#EnableInterface
4	#DisableInterface
5		Takes an u32 and an u64. Returns an output u32.
6		Takes an u32 and an u64. Returns an output u32.
7	#GetCtrlInCompletionEvent
8		No input. Returns 0x84 bytes of output.
9	#GetCtrlOutCompletionEvent
10		No input. Returns 0x84 bytes of output.
11		No input/output.

GetDsEndpoint

Takes a type-5 buffer and returns an #IDsEndpoint. Manu uses this twice for getting two endpoint sessions, with the following 0x7-byte buffer data:

• First endpoint: 0x07, 0x05, 0x80, 0x02, 0x00, 0x02, 0x00.
• Second endpoint: Same as above except byte2 is 0x00.

Each field is an u8, except for offset 0x4-0x5 which is an u16.

This structure matches libusb_endpoint_descriptor.

GetSetupEvent

Returns an event handle for interface setup changes.

EnableInterface

Takes no arguments. Enables the current interface.

Only one interface can be enabled at time, this indicates which interface is actually used for USB.

DisableInterface

Takes no arguments. Disables the current interface.

GetCtrlInCompletionEvent

Returns an event handle for polling the completion of input control commands.

GetCtrlOutCompletionEvent

Returns an event handle for polling the completion of output control commands.

IDsEndpoint

Cmd	Name	Notes
0	#PostBufferAsync
1		No input/output.
2		No input. Returns an output handle?
3	#GetReportData
4		No input/output.
5		Takes an input u8, no output.

PostBufferAsync

Takes an u32 (size) and an u64 (buffer). Returns an output u32.

GetReportData

Returns 0x84 bytes of report data from the endpoint.

usb:hs

General USB devices usage, used by hid-sysmodule and bsdsockets-sysmodule.

usb:pd

Only system-titles with access to this are PTM and AM.

usb:pd:c

USB-sysmodule symbols for this refer to "Cradle", which is the Dock.

usb:pm

Presumably Power Management, only system-title using this is PTM.