USB_PIPE_CTRL_XFER(9F) Kernel Functions for Drivers USB_PIPE_CTRL_XFER(9F)

usb_pipe_ctrl_xfer, usb_pipe_ctrl_xfer_wait - USB control pipe transfer functions

#include <sys/usb/usba.h>
int usb_pipe_ctrl_xfer(usb_pipe_handle_t pipe_handle,
     usb_ctrl_req_t *request, usb_flags_t flags);

int usb_pipe_ctrl_xfer_wait(usb_pipe_handle_t pipe_handle,
     usb_ctrl_setup_t *setup, mblk_t **data,
     usb_cr_t * completion_reason, usb_cb_flags_t *cb_flags,
     usb_flags_t flags);

illumos DDI specific (illumos DDI)

For usb_pipe_ctrl_xfer():


Control pipe handle on which request is made.


Pointer to control transfer request.


USB_FLAGS_SLEEP is the only flag recognized. Wait for all pending request callbacks to complete.

For usb_pipe_ctrl_xfer_wait():


Control pipe handle on which request is made.


Pointer to setup parameters. (See below.)


Pointer to mblk containing data bytes to transfer with command. Ignored if NULL.


Returns overall completion status. Ignored if NULL. Please see usb_callback_flags(9S) for more information.


Returns flags set either during autoclearing or some other callback, which indicate recovery handling done in callback. Ignored if NULL.


No flags are recognized. Reserved for future expansion.

The usb_pipe_ctrl_xfer() function requests the USBA framework to perform a transfer through a USB control pipe. The request is passed to the host controller driver (HCD), which performs the necessary transactions to complete the request. Requests are synchronous when USB_FLAGS_SLEEP is specified in flags; calls for synchronous requests do not return until their transaction is completed. Asynchronous requests (made without specifying the USB_FLAGS_SLEEP flag) notifies the caller of their completion via a callback function.

The usb_pipe_ctrl_xfer_wait() function is a wrapper around usb_pipe_ctrl_xfer() that performs allocation and deallocation of all required data structures, and a synchronous control-pipe transfer. It takes a usb_ctrl_setup_t containing most usb setup parameters as an argument:

 uchar_t      bmRequestType   /* characteristics of request. */
                              /* (See USB 2.0 spec, section 9.3). */
                              /*  Combine one direction of:   */
                              /*      USB_DEV_REQ_HOST_TO_DEV */
                              /*      USB_DEV_REQ_DEV_TO_HOST */
                              /*  with one request type of:   */
                              /*      USB_DEV_REQ_TYPE_STANDARD */
                              /*      USB_DEV_REQ_TYPE_CLASS  */
                              /*      USB_DEV_REQ_TYPE_VENDOR */
                              /*  with one recipient type of: */
                              /*      USB_DEV_REQ_RCPT_DEV    */
                              /*      USB_DEV_REQ_RCPT_IF     */
                              /*      USB_DEV_REQ_RCPT_EP     */
                              /*      USB_DEV_REQ_RCPT_OTHER. */
 uchar_t      bRequest        /* request or command.          */
                              /* (See USB 2.0 spec, section   */
                              /* 9.3 for standard commands.)  */
 uint16_t     wValue         /* value which varies according to */
                              /* the command (bRequest).      */
 uint16_t     wIndex          /* value which varies according to */
                              /* the command, typically used to */
                              /* pass an index or offset. */
 uint16_t     wLength         /* number of data bytes to transfer */
                              /* with command, if any.  Same as */
                              /* size of mblk "data" below.   */
 usb_req_attrs_t attrs;       /* required request attributes */

Please see usb_request_attributes(9S), or refer to Section 5.5 of the USB 2.0 specification for more information on these parameters. (The USB 2.0 specification is available at

Mblks for data are allocated optionally when a request is allocated via usb_alloc_ctrl_req(9F) by passing a positive value for the len argument. Control requests passing or receiving no supplemental data need not allocate an mblk.

For usb_pipe_ctrl_xfer():


Transfer was successful.


Request is NULL.


Called from interrupt context with the USB_FLAGS_SLEEP flag set.


The request has been freed or otherwise invalidated.

A set of conflicting attributes were specified. See usb_request_attributes(9S).

The normal and/or exception callback is NULL and USB_FLAGS_SLEEP is not set.

Data space not provided to a control request while ctrl_wLength is nonzero.


Pipe handle is NULL or invalid.

Pipe is closing or closed.


Memory, descriptors or other resources unavailable.


Host controller is in error state.


An asynchronous transfer failed or an internal error occurred.

The pipe is in an unsuitable state (error, busy, not ready).

Additional status information may be available in the ctrl_completion_reason and ctrl_cb_flags fields of the request. Please see usb_callback_flags(9S) and usb_completion_reason(9S) for more information.

For usb_pipe_ctrl_xfer_wait():


Request was successful.


Called from interrupt context.


dip is NULL.

Any error code returned by usb_pipe_ctrl_xfer().

Additional status information may be available in the ctrl_completion_reason and ctrl_cb_flags fields of the request. Please see usb_callback_flags(9S) and usb_completion_reason(9S) for more information.

The usb_pipe_ctrl_xfer() function may be called from kernel or user context without regard to arguments and from the interrupt context only when the USB_FLAGS_SLEEP flag is clear.

The usb_pipe_ctrl_xfer_wait() function may be called from kernel or user context.

  /* Allocate, initialize and issue a synchronous control request. */
  usb_ctrl_req_t ctrl_req;
  void control_pipe_exception_callback(
      usb_pipe_handle_t, usb_ctrl_req_t*);
  ctrl_req = usb_alloc_ctrl_req(dip, 0, USB_FLAGS_SLEEP);
  ctrl_req->ctrl_bmRequestType = USB_DEV_REQ_HOST_TO_DEV |
  ctrl_req->ctrl_bRequest     = (uint8_t)USB_PRINTER_SOFT_RESET;
  ctrl_req->ctrl_exc_cb       = control_pipe_exception_callback;
  if ((rval = usb_pipe_ctrl_xfer(pipe, ctrl_req, USB_FLAGS_SLEEP))
      != USB_SUCCESS) {
          cmn_err (CE_WARN, "%s%d: Error issuing USB cmd.",
              ddi_driver_name(dip), ddi_get_instance(dip));
   * Allocate, initialize and issue an asynchronous control request to
   * read a configuration descriptor.
  usb_ctrl_req_t *ctrl_req;
  void control_pipe_normal_callback(
      usb_pipe_handle_t, usb_ctrl_req_t*);
  void control_pipe_exception_callback(
      usb_pipe_handle_t, usb_ctrl_req_t*);
  struct buf *bp = ...;
  ctrl_req =
      usb_alloc_ctrl_req(dip, sizeof(usb_cfg_descr_t), USB_FLAGS_SLEEP);
  ctrl_req->ctrl_bmRequestType = USB_DEV_REQ_DEV_TO_HOST |
  ctrl_req->ctrl_wLength      = sizeof(usb_cfg_descr_t);
  ctrl_req->ctrl_wValue       = USB_DESCR_TYPE_SETUP_CFG | 0;
  ctrl_req->ctrl_bRequest     = (uint8_t)USB_REQ_GET_DESCR;
  ctrl_req->ctrl_cb           = control_pipe_normal_callback;
  ctrl_req->ctrl_exc_cb       = control_pipe_exception_callback;
  /* Make buf struct available to callback handler. */
  ctrl_req->ctrl_client_private = (usb_opaque_t)bp;
  if ((rval = usb_pipe_ctrl_xfer(pipe, ctrl_req, USB_FLAGS_NOSLEEP))
      != USB_SUCCESS) {
          cmn_err (CE_WARN, "%s%d: Error issuing USB cmd.",
              ddi_driver_name(dip), ddi_get_instance(dip));
  /* Call usb_pipe_ctrl_xfer_wait() to get device status. */
  mblk_t *data;
  usb_cr_t completion_reason;
  usb_cb_flags_t callback_flags;
  usb_ctrl_setup_t setup_params = {
      USB_DEV_REQ_DEV_TO_HOST |       /* bmRequestType */
      USB_REQ_GET_STATUS,             /* bRequest */
      0,                              /* wValue */
      0,                              /* wIndex */
      USB_GET_STATUS_LEN,             /* wLength */
      0                               /* attributes. */
  if (usb_pipe_ctrl_xfer_wait(
      0) != USB_SUCCESS) {
          cmn_err (CE_WARN,
              "%s%d: USB get status command failed: "
              "reason=%d callback_flags=0x%x",
              ddi_driver_name(dip), ddi_get_instance(dip),
              completion_reason, callback_flags);
          return (EIO);
  /* Check data length.  Should be USB_GET_STATUS_LEN (2 bytes). */
  length_returned = data->b_wptr - data->b_rptr;
  if (length_returned != USB_GET_STATUS_LEN) {
        cmn_err (CE_WARN,
            "%s%d: USB get status command returned %d bytes of data.",
            ddi_driver_name(dip), ddi_get_instance(dip), length_returned);
          return (EIO);
  /* Retrieve data in endian neutral way. */
  status = (*(data->b_rptr + 1) << 8) | *(data->b_rptr);

See attributes(5) for descriptions of the following attributes:

Architecture PCI-based systems
Interface stability Committed

attributes(5), usb_alloc_request(9F), usb_get_cfg(9F), usb_get_status(9F), usb_pipe_bulk_xfer(9F), usb_pipe_intr_xfer(9F), usb_pipe_isoc_xfer(9F), usb_pipe_xopen(9F), usb_pipe_reset(9F), usb_pipe_get_state(9F), usb_bulk_request(9S), usb_callback_flags(9S), usb_ctrl_request(9S), usb_completion_reason(9S), usb_intr_request(9S), usb_isoc_request(9S)
September 16, 2016 OmniOS