USBA_HCDI_PIPE_OPEN(9E) Driver Entry Points USBA_HCDI_PIPE_OPEN(9E)

usba_hcdi_pipe_open, usba_hcdi_pipe_close
open and close a USB pipe

#include <sys/usb/usba/hcdi.h>

int
prefix_hcdi_pipe_open(usba_pipe_handle_data_t *ph, usb_flags_t usb_flags);

int
prefix_hcdi_pipe_close(usba_pipe_handle_data_t *ph, usb_flags_t usb_flags);

Volatile - illumos USB HCD private function

This is a private function that is not part of the stable DDI. It may be removed or changed at any time.

ph
A pointer to a USB pipe handle as defined in usba_pipe_handle_data(9S).
usb_flags
Flags which describe how allocations should be performed. Valid flags are:
USB_FLAGS_NOSLEEP
Do not block waiting for memory. If memory is not available the allocation will fail.
USB_FLAGS_SLEEP
Perform a blocking allocation. If memory is not available, the function will wait until memory is made available.

Note, the request may still fail even if USB_FLAGS_SLEEP is specified.

The usba_hcdi_pipe_open() and usba_hcdi_pipe_close() entry points are called by the USB framework whenever a client, or the framework itself, need to open or close a specific pipe. For additional background see usba_hcdi(9E).

When a pipe is opened, the host controller driver is responsible for preparing the specified endpoint for performing transfers. This may include allocating bandwidth, programming the controller, and more. When the pipe is closed, the host controller driver is responsible for cleaning up any resources that were allocated during the open call.

The pipe handle, ph, identifies the endpoint that it the USBA is trying to open or close through its endpoint descriptor in the p_ep member. The endpoint descriptor is described in usb_ep_descr(9S). From the endpoint descriptor the driver can determine the type of endpoint, what the address of the endpoint is, and what direction the endpoint is in. When combined, these uniquely describe the pipe.

To open a pipe, the driver may need additional companion endpoint descriptors. If these are available, they will be in the p_xep member of the pipe handle. See usb_ep_xdescr(9S) for more information on how to determine which descriptors are present and get the information encoded in them.

Host controller drivers should check the USB address of the USB device that ph belongs to. The driver may be asked to open a pipe to the root hub. As the root hub is often synthetic, the driver may need to take a different path than normal.

A given endpoint on a device can only be opened once. If there's a request to open an already open endpoint, then the request to open the pipe should be failed.

By the time the call to open a pipe returns, the driver should expect that any of the pipe transfer or reset entry points will be called on the pipe.

A driver can establish private data on an endpoint. During pipe open it may set the p_hcd_private member to any value. Generally this points to an allocated structure that contains data specific to the host controller. This value will remain on the pipe handle. It is the responsibility of the driver to clear the data when the pipe is closed.

When a pipe is closed, the driver must clean up all of the resources that it allocated when opening the pipe. For non-periodic transfers, the host controller driver may assume that there are no outstanding transfers that need to be cleaned up. However, the same is not true for periodic pipes.

For pipes that have outstanding periodic transfers, the host controller driver needs to clean them up and quiesce them as though a call to either usba_hcdi_pipe_stop_intr_polling(9E) or usba_hcdi_pipe_stop_isoc_polling(9E) had been called.

Just as with opening the pipe, the driver should pay attention to the address of the USB device, as it may be the root hub, which may be a synthetic pipe.

When a call to usba_hcdi_pipe_close() completes, the device should be in a state that the pipe can be opened again.

Upon successful completion, the usba_hcdi_pipe_open() and uba_hcdi_pipe_close() functions should return USB_SUCCESS. Otherwise, it should return the appropriate USB error. If uncertain, use USB_FAILURE.

usba_hcdi(9E), usba_hcdi_pipe_stop_intr_polling(9E), usba_hcdi_pipe_stop_isoc_polling(9E), usb_ep_descr(9S), usb_ep_xdescr(9S), usba_pipe_handle_data(9S)
February 15, 2020 OmniOS