USB driver

O driver de imagem estática do modo kernel para barramentos USB suporta um único ponto de extremidade de controle, juntamente com vários pontos de extremidade de interrupção, entrada em massa e saída em massa. The control and interrupt endpoints are accessible using I/O control codes and DeviceIoControl. The bulk endpoints are accessible using ReadFile and WriteFile.

Before calling DeviceIoControl, ReadFile, or WriteFile, you must call CreateFile (all described in the Microsoft Windows SDK documentation) to obtain a device handle. For devices that support no more than one of each endpoint type (control, interrupt, bulk IN, bulk OUT), a single call to CreateFile opens transfer pipes to each endpoint.

For devices that support multiple interrupt or bulk endpoints, a single call to CreateFile opens transfer pipes to the highest-numbered endpoint of each type. Se você quiser usar um ponto de extremidade diferente, deverá fazer o seguinte:

1. Call DeviceIoControl, specifying an I/O control code of IOCTL_GET_PIPE_CONFIGURATION, to determine a port's endpoint index numbers (that is, indexes into the returned USBSCAN_PIPE_INFORMATION structure array). Note that these index numbers are not the endpoint numbers described in the Universal Serial Bus Specification.

2. Append a backslash and the endpoint's index number to the port name returned by IStiDeviceControl::GetMyDevicePortName when calling CreateFile.

Por exemplo, suponha que um dispositivo (com um nome de porta "usbscan0") tenha dois pontos de extremidade de cada tipo (interrupção, entrada em massa, saída em massa), com números de índice da seguinte maneira:

Index	Tipo	Endpoint#
0	Interrupt	0x01
1	Bulk IN	0x82
2	Bulk IN	0x83
3	Bulk OUT	0x04
4	Bulk OUT	0x05
5	Interrupt	0x06

If you call CreateFile with a port name of "usbscan0", the function opens transfer pipes to endpoints with index values of 2, 4, and 5, as well as the control endpoint.

If you call CreateFile with a port name of "usbscan0\1", the function opens transfer pipes to endpoints with index values of 1, 4, and 5, as well as the control endpoint.

For this device, if you want to use interrupt endpoint 0, bulk IN endpoint 1, and bulk OUT endpoint 3, call CreateFile three times, specifying port names of "usbscan0\0", "usbscan0\1", and "usbscan0\3". Isso cria três identificadores de dispositivo. Whenever a subsequent call to DeviceIoControl, ReadFile, or WriteFile is made, the device handle associated with the desired pipe should be specified.

Because only one control endpoint is supported, specifying any I/O control code that uses the control pipe causes the driver to use the proper endpoint, regardless of which endpoint (if any) was specified to CreateFile.

Para obter descrições de todos os códigos de controle de E /S, consulte Códigos de controle de E/S de imagem estática USB.

O driver USB de modo kernel não implementa um pacote ou protocolo de mensagem. As operações de leitura não exigem nenhum alinhamento de pacote específico, mas um melhor desempenho pode ser alcançado se as solicitações de leitura estiverem alinhadas aos limites máximos de tamanho de pacote. The maximum packet size can be obtained using the IOCTL_GET_CHANNEL_ALIGN_RQST I/O control code.