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USBD_TRANSFER(9) FreeBSD Kernel Developer's Manual USBD_TRANSFER(9) NAME usbd_setup_xfer, usbd_transfer - submit USB data transfers SYNOPSIS #include <dev/usb/usb.h> #include <dev/usb/usbdi.h> void usbd_setup_xfer(struct usbd_xfer *xfer, struct usbd_pipe *pipe, void *priv, void *buffer, uint32_t length, uint16_t flags, uint32_t timeout, usbd_callback callback); usbd_status usbd_transfer(struct usbd_xfer *xfer); DESCRIPTION These functions provide a controller independent mechanism to perform USB data transfers. They make use of a pipe created by usbd_open_pipe(9) or usbd_open_pipe_intr(9). The function usbd_setup_xfer() is used to initialize the structure pointed to by xfer, describing an individual transfer to submit. It takes the following arguments: xfer A pointer to an existing structure describing a transfer. pipe A pointer to a pipe associated with the endpoint for the transfer. priv A pointer to a private cookie untouched by the USB stack for reuse in the callback. buffer A pointer to the data buffer. length The total length of the data to read or write. flags The characteristics of the transfer: USBD_NO_COPY Do not copy data between buffer and the DMA buffer. USBD_SYNCHRONOUS Causes usbd_transfer() to sleep until the I/O transfer is complete or the timeout expires. USBD_SHORT_XFER_OK Do not report short reads, when the length of the data read is lower than length, as errors. USBD_FORCE_SHORT_XFER Submit a supplementary zero length packet at the end of the written data. Some requests may need such packets in order to be properly terminated. USBD_CATCH Used in conjunction with the USBD_SYNCHRONOUS flag to pass the PCATCH flag to tsleep(9) in order to check for signals before and after sleeping. timeout Timeout of the transfer in milliseconds. callback A routine invoked upon completion of the transfer whether successful or not. The function usbd_transfer() is used to submit the USB transfer described by xfer to the corresponding usb(4) host controller to perform I/O with devices. CONTEXT usbd_setup_xfer() can be called during autoconf, from process context, or from interrupt context. usbd_transfer() can be called during autoconf, from process context, or from interrupt context if USBD_SYNCHRONOUS has not been passed via flags. SEE ALSO ehci(4), ohci(4), uhci(4), usb(4), tsleep(9), usbd_open_pipe(9), usbd_open_pipe_intr(9) FreeBSD 14.1-RELEASE-p8 May 4, 2015 FreeBSD 14.1-RELEASE-p8