633 lines
17 KiB
Groff
633 lines
17 KiB
Groff
.\"
|
|
.\" Copyright (c) 2005 Ian Dowse <iedowse@FreeBSD.org>
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
.\" SUCH DAMAGE.
|
|
.\"
|
|
.\" $FreeBSD$
|
|
.Dd November 14, 2016
|
|
.Dt USBDI 9
|
|
.Os
|
|
.Sh NAME
|
|
.Nm usb_fifo_alloc_buffer ,
|
|
.Nm usb_fifo_attach ,
|
|
.Nm usb_fifo_detach ,
|
|
.Nm usb_fifo_free_buffer ,
|
|
.Nm usb_fifo_get_data ,
|
|
.Nm usb_fifo_get_data_buffer ,
|
|
.Nm usb_fifo_get_data_error ,
|
|
.Nm usb_fifo_get_data_linear ,
|
|
.Nm usb_fifo_put_bytes_max ,
|
|
.Nm usb_fifo_put_data ,
|
|
.Nm usb_fifo_put_data_buffer ,
|
|
.Nm usb_fifo_put_data_error ,
|
|
.Nm usb_fifo_put_data_linear ,
|
|
.Nm usb_fifo_reset ,
|
|
.Nm usb_fifo_softc ,
|
|
.Nm usb_fifo_wakeup ,
|
|
.Nm usbd_do_request ,
|
|
.Nm usbd_do_request_flags ,
|
|
.Nm usbd_errstr ,
|
|
.Nm usbd_lookup_id_by_info ,
|
|
.Nm usbd_lookup_id_by_uaa ,
|
|
.Nm usbd_transfer_clear_stall ,
|
|
.Nm usbd_transfer_drain ,
|
|
.Nm usbd_transfer_pending ,
|
|
.Nm usbd_transfer_poll ,
|
|
.Nm usbd_transfer_setup ,
|
|
.Nm usbd_transfer_start ,
|
|
.Nm usbd_transfer_stop ,
|
|
.Nm usbd_transfer_submit ,
|
|
.Nm usbd_transfer_unsetup ,
|
|
.Nm usbd_xfer_clr_flag ,
|
|
.Nm usbd_xfer_frame_data ,
|
|
.Nm usbd_xfer_frame_len ,
|
|
.Nm usbd_xfer_get_frame ,
|
|
.Nm usbd_xfer_get_priv ,
|
|
.Nm usbd_xfer_is_stalled ,
|
|
.Nm usbd_xfer_max_framelen ,
|
|
.Nm usbd_xfer_max_frames ,
|
|
.Nm usbd_xfer_max_len ,
|
|
.Nm usbd_xfer_set_flag ,
|
|
.Nm usbd_xfer_set_frame_data ,
|
|
.Nm usbd_xfer_set_frame_len ,
|
|
.Nm usbd_xfer_set_frame_offset ,
|
|
.Nm usbd_xfer_set_frames ,
|
|
.Nm usbd_xfer_set_interval ,
|
|
.Nm usbd_xfer_set_priv ,
|
|
.Nm usbd_xfer_set_stall ,
|
|
.Nm usbd_xfer_set_timeout ,
|
|
.Nm usbd_xfer_softc ,
|
|
.Nm usbd_xfer_state ,
|
|
.Nm usbd_xfer_status
|
|
.Nd Universal Serial Bus driver programming interface
|
|
.Sh SYNOPSIS
|
|
.In dev/usb/usb.h
|
|
.In dev/usb/usbdi.h
|
|
.In dev/usb/usbdi_util.h
|
|
.Ft "usb_error_t"
|
|
.Fo "usbd_transfer_setup"
|
|
.Fa "struct usb_device *udev"
|
|
.Fa "const uint8_t *ifaces"
|
|
.Fa "struct usb_xfer **pxfer"
|
|
.Fa "const struct usb_config *setup_start"
|
|
.Fa "uint16_t n_setup"
|
|
.Fa "void *priv_sc"
|
|
.Fa "struct mtx *priv_mtx"
|
|
.Fc
|
|
.Ft "void"
|
|
.Fo "usbd_transfer_unsetup"
|
|
.Fa "struct usb_xfer **pxfer"
|
|
.Fa "uint16_t n_setup"
|
|
.Fc
|
|
.Ft "void"
|
|
.Fo "usbd_transfer_start"
|
|
.Fa "struct usb_xfer *xfer"
|
|
.Fc
|
|
.Ft "void"
|
|
.Fo "usbd_transfer_stop"
|
|
.Fa "struct usb_xfer *xfer"
|
|
.Fc
|
|
.Ft "void"
|
|
.Fo "usbd_transfer_drain"
|
|
.Fa "struct usb_xfer *xfer"
|
|
.Fc
|
|
.Sh DESCRIPTION
|
|
The Universal Serial Bus (USB) driver programming interface provides
|
|
USB peripheral drivers with a host controller independent API for
|
|
controlling and communicating with USB peripherals.
|
|
The
|
|
.Nm usb
|
|
module supports both USB Host and USB Device side mode.
|
|
.Sh USB TRANSFER MANAGEMENT FUNCTIONS
|
|
The USB standard defines four types of USB transfers.
|
|
.
|
|
Control transfers, Bulk transfers, Interrupt transfers and Isochronous
|
|
transfers.
|
|
.
|
|
All the transfer types are managed using the following five functions:
|
|
.
|
|
.Pp
|
|
.
|
|
.Fn usbd_transfer_setup
|
|
This function will allocate memory for and initialise an array of USB
|
|
transfers and all required DMA memory.
|
|
.
|
|
This function can sleep or block waiting for resources to become
|
|
available.
|
|
.Fa udev
|
|
is a pointer to "struct usb_device".
|
|
.Fa ifaces
|
|
is an array of interface index numbers to use.
|
|
See "if_index".
|
|
.Fa pxfer
|
|
is a pointer to an array of USB transfer pointers that are initialized
|
|
to NULL, and then pointed to allocated USB transfers.
|
|
.Fa setup_start
|
|
is a pointer to an array of USB config structures.
|
|
.Fa n_setup
|
|
is a number telling the USB system how many USB transfers should be
|
|
setup.
|
|
.Fa priv_sc
|
|
is the private softc pointer, which will be used to initialize
|
|
"xfer->priv_sc".
|
|
.Fa priv_mtx
|
|
is the private mutex protecting the transfer structure and the
|
|
softc.
|
|
This pointer is used to initialize "xfer->priv_mtx".
|
|
This function returns zero upon success.
|
|
A non-zero return value indicates failure.
|
|
.
|
|
.Pp
|
|
.
|
|
.Fn usbd_transfer_unsetup
|
|
This function will release the given USB transfers and all allocated
|
|
resources associated with these USB transfers.
|
|
.Fa pxfer
|
|
is a pointer to an array of USB transfer pointers, that may be NULL,
|
|
that should be freed by the USB system.
|
|
.Fa n_setup
|
|
is a number telling the USB system how many USB transfers should be
|
|
unsetup.
|
|
.
|
|
This function can sleep waiting for USB transfers to complete.
|
|
.
|
|
This function is NULL safe with regard to the USB transfer structure
|
|
pointer.
|
|
.
|
|
It is not allowed to call this function from the USB transfer
|
|
callback.
|
|
.
|
|
.Pp
|
|
.
|
|
.Fn usbd_transfer_start
|
|
This function will start the USB transfer pointed to by
|
|
.Fa xfer ,
|
|
if not already started.
|
|
.
|
|
This function is always non-blocking and must be called with the
|
|
so-called private USB mutex locked.
|
|
.
|
|
This function is NULL safe with regard to the USB transfer structure
|
|
pointer.
|
|
.
|
|
.Pp
|
|
.
|
|
.Fn usbd_transfer_stop
|
|
This function will stop the USB transfer pointed to by
|
|
.Fa xfer ,
|
|
if not already stopped.
|
|
.
|
|
This function is always non-blocking and must be called with the
|
|
so-called private USB mutex locked.
|
|
.
|
|
This function can return before the USB callback has been called.
|
|
.
|
|
This function is NULL safe with regard to the USB transfer structure
|
|
pointer.
|
|
.
|
|
If the transfer was in progress, the callback will called with
|
|
"USB_ST_ERROR" and "error = USB_ERR_CANCELLED".
|
|
.
|
|
.Pp
|
|
.
|
|
.Fn usbd_transfer_drain
|
|
This function will stop an USB transfer, if not already stopped and
|
|
wait for any additional USB hardware operations to complete.
|
|
.
|
|
Buffers that are loaded into DMA using "usbd_xfer_set_frame_data()" can
|
|
safely be freed after that this function has returned.
|
|
.
|
|
This function can block the caller and will not return before the USB
|
|
callback has been called.
|
|
.
|
|
This function is NULL safe with regard to the USB transfer structure
|
|
pointer.
|
|
.
|
|
.Sh USB TRANSFER CALLBACK
|
|
.
|
|
The USB callback has three states.
|
|
.
|
|
USB_ST_SETUP, USB_ST_TRANSFERRED and USB_ST_ERROR.
|
|
USB_ST_SETUP is the initial state.
|
|
.
|
|
After the callback has been called with this state it will always be
|
|
called back at a later stage in one of the other two states.
|
|
.
|
|
The USB callback should not restart the USB transfer in case the error
|
|
cause is USB_ERR_CANCELLED.
|
|
.
|
|
The USB callback is protected from recursion.
|
|
.
|
|
That means one can start and stop whatever transfer from the callback
|
|
of another transfer one desires.
|
|
.
|
|
Also the transfer that is currently called back.
|
|
.
|
|
Recursion is handled like this that when the callback that wants to
|
|
recurse returns it is called one more time.
|
|
.
|
|
.
|
|
.Pp
|
|
.
|
|
.Fn usbd_transfer_submit
|
|
This function should only be called from within the USB callback and
|
|
is used to start the USB hardware.
|
|
.
|
|
An USB transfer can have multiple frames consisting of one or more USB
|
|
packets making up an I/O vector for all USB transfer types.
|
|
.
|
|
.Bd -literal -offset indent
|
|
void
|
|
usb_default_callback(struct usb_xfer *xfer, usb_error_t error)
|
|
{
|
|
int actlen;
|
|
|
|
usbd_xfer_status(xfer, &actlen, NULL, NULL, NULL);
|
|
|
|
switch (USB_GET_STATE(xfer)) {
|
|
case USB_ST_SETUP:
|
|
/*
|
|
* Setup xfer frame lengths/count and data
|
|
*/
|
|
usbd_transfer_submit(xfer);
|
|
break;
|
|
|
|
case USB_ST_TRANSFERRED:
|
|
/*
|
|
* Read usb frame data, if any.
|
|
* "actlen" has the total length for all frames
|
|
* transferred.
|
|
*/
|
|
break;
|
|
|
|
default: /* Error */
|
|
/*
|
|
* Print error message and clear stall
|
|
* for example.
|
|
*/
|
|
break;
|
|
}
|
|
/*
|
|
* Here it is safe to do something without the private
|
|
* USB mutex locked.
|
|
*/
|
|
return;
|
|
}
|
|
.Ed
|
|
.
|
|
.Sh USB CONTROL TRANSFERS
|
|
An USB control transfer has three parts.
|
|
.
|
|
First the SETUP packet, then DATA packet(s) and then a STATUS
|
|
packet.
|
|
.
|
|
The SETUP packet is always pointed to by frame 0 and the
|
|
length is set by
|
|
.Fn usbd_xfer_frame_len
|
|
also if there should not be
|
|
sent any SETUP packet!
|
|
If an USB control transfer has no DATA stage,
|
|
then the number of frames should be set to 1.
|
|
.
|
|
Else the default number of frames is 2.
|
|
.
|
|
.Bd -literal -offset indent
|
|
|
|
Example1: SETUP + STATUS
|
|
usbd_xfer_set_frames(xfer, 1);
|
|
usbd_xfer_set_frame_len(xfer, 0, 8);
|
|
usbd_transfer_submit(xfer);
|
|
|
|
Example2: SETUP + DATA + STATUS
|
|
usbd_xfer_set_frames(xfer, 2);
|
|
usbd_xfer_set_frame_len(xfer, 0, 8);
|
|
usbd_xfer_set_frame_len(xfer, 1, 1);
|
|
usbd_transfer_submit(xfer);
|
|
|
|
Example3: SETUP + DATA + STATUS - split
|
|
1st callback:
|
|
usbd_xfer_set_frames(xfer, 1);
|
|
usbd_xfer_set_frame_len(xfer, 0, 8);
|
|
usbd_transfer_submit(xfer);
|
|
|
|
2nd callback:
|
|
/* IMPORTANT: frbuffers[0] must still point at the setup packet! */
|
|
usbd_xfer_set_frames(xfer, 2);
|
|
usbd_xfer_set_frame_len(xfer, 0, 0);
|
|
usbd_xfer_set_frame_len(xfer, 1, 1);
|
|
usbd_transfer_submit(xfer);
|
|
|
|
Example4: SETUP + STATUS - split
|
|
1st callback:
|
|
usbd_xfer_set_frames(xfer, 1);
|
|
usbd_xfer_set_frame_len(xfer, 0, 8);
|
|
usbd_xfer_set_flag(xfer, USB_MANUAL_STATUS);
|
|
usbd_transfer_submit(xfer);
|
|
|
|
2nd callback:
|
|
usbd_xfer_set_frames(xfer, 1);
|
|
usbd_xfer_set_frame_len(xfer, 0, 0);
|
|
usbd_xfer_clr_flag(xfer, USB_MANUAL_STATUS);
|
|
usbd_transfer_submit(xfer);
|
|
|
|
.Ed
|
|
.Sh USB TRANSFER CONFIG
|
|
To simply the search for endpoints the
|
|
.Nm usb
|
|
module defines a USB config structure where it is possible to specify
|
|
the characteristics of the wanted endpoint.
|
|
.Bd -literal -offset indent
|
|
|
|
struct usb_config {
|
|
bufsize,
|
|
callback
|
|
direction,
|
|
endpoint,
|
|
frames,
|
|
index flags,
|
|
interval,
|
|
timeout,
|
|
type,
|
|
};
|
|
|
|
.Ed
|
|
.
|
|
.Pp
|
|
.Fa type
|
|
field selects the USB pipe type.
|
|
.
|
|
Valid values are: UE_INTERRUPT, UE_CONTROL, UE_BULK,
|
|
UE_ISOCHRONOUS.
|
|
.
|
|
The special value UE_BULK_INTR will select BULK and INTERRUPT pipes.
|
|
.
|
|
This field is mandatory.
|
|
.
|
|
.Pp
|
|
.Fa endpoint
|
|
field selects the USB endpoint number.
|
|
.
|
|
A value of 0xFF, "-1" or "UE_ADDR_ANY" will select the first matching
|
|
endpoint.
|
|
.
|
|
This field is mandatory.
|
|
.
|
|
.Pp
|
|
.Fa direction
|
|
field selects the USB endpoint direction.
|
|
.
|
|
A value of "UE_DIR_ANY" will select the first matching endpoint.
|
|
.
|
|
Else valid values are: "UE_DIR_IN" and "UE_DIR_OUT".
|
|
.
|
|
"UE_DIR_IN" and "UE_DIR_OUT" can be binary OR'ed by "UE_DIR_SID" which
|
|
means that the direction will be swapped in case of
|
|
USB_MODE_DEVICE.
|
|
.
|
|
Note that "UE_DIR_IN" refers to the data transfer direction of the
|
|
"IN" tokens and "UE_DIR_OUT" refers to the data transfer direction of
|
|
the "OUT" tokens.
|
|
.
|
|
This field is mandatory.
|
|
.
|
|
.Pp
|
|
.Fa interval
|
|
field selects the interrupt interval.
|
|
.
|
|
The value of this field is given in milliseconds and is independent of
|
|
device speed.
|
|
.
|
|
Depending on the endpoint type, this field has different meaning:
|
|
.Bl -tag -width "UE_ISOCHRONOUS"
|
|
.It UE_INTERRUPT
|
|
"0" use the default interrupt interval based on endpoint descriptor.
|
|
"Else" use the given value for polling rate.
|
|
.It UE_ISOCHRONOUS
|
|
"0" use default.
|
|
"Else" the value is ignored.
|
|
.It UE_BULK
|
|
.It UE_CONTROL
|
|
"0" no transfer pre-delay.
|
|
"Else" a delay as given by this field in
|
|
milliseconds is inserted before the hardware is started when
|
|
"usbd_transfer_submit()" is called.
|
|
.Pp
|
|
NOTE: The transfer timeout, if any, is started after that the
|
|
pre-delay has elapsed!
|
|
.El
|
|
.
|
|
.Pp
|
|
.Fa timeout
|
|
field, if non-zero, will set the transfer timeout in milliseconds.
|
|
If the "timeout" field is zero and the transfer type is ISOCHRONOUS a
|
|
timeout of 250ms will be used.
|
|
.
|
|
.Pp
|
|
.Fa frames
|
|
field sets the maximum number of frames.
|
|
If zero is specified it will yield the following results:
|
|
.Bl -tag -width "UE_INTERRUPT"
|
|
.It UE_BULK
|
|
xfer->nframes = 1;
|
|
.It UE_INTERRUPT
|
|
xfer->nframes = 1;
|
|
.It UE_CONTROL
|
|
xfer->nframes = 2;
|
|
.It UE_ISOCHRONOUS
|
|
Not allowed.
|
|
Will cause an error.
|
|
.El
|
|
.
|
|
.Pp
|
|
.Fa ep_index
|
|
field allows you to give a number, in case more endpoints match the
|
|
description, that selects which matching "ep_index" should be used.
|
|
.
|
|
.Pp
|
|
.Fa if_index
|
|
field allows you to select which of the interface numbers in the
|
|
"ifaces" array parameter passed to "usbd_transfer_setup" that should
|
|
be used when setting up the given USB transfer.
|
|
.
|
|
.Pp
|
|
.Fa flags
|
|
field has type "struct usb_xfer_flags" and allows one to set initial
|
|
flags an USB transfer.
|
|
Valid flags are:
|
|
.Bl -tag -width "force_short_xfer"
|
|
.It force_short_xfer
|
|
This flag forces the last transmitted USB packet to be short.
|
|
A short packet has a length of less than "xfer->max_packet_size", which
|
|
derives from "wMaxPacketSize".
|
|
This flag can be changed during operation.
|
|
.It short_xfer_ok
|
|
This flag allows the received transfer length, "xfer->actlen" to be
|
|
less than "xfer->sumlen" upon completion of a transfer.
|
|
This flag can be changed during operation.
|
|
.It short_frames_ok
|
|
This flag allows the reception of multiple short USB frames.
|
|
This flag
|
|
only has effect for BULK and INTERRUPT endpoints and if the number of
|
|
frames received is greater than 1.
|
|
This flag can be changed during operation.
|
|
.It pipe_bof
|
|
This flag causes a failing USB transfer to remain first in the PIPE
|
|
queue except in the case of "xfer->error" equal to
|
|
"USB_ERR_CANCELLED".
|
|
No other USB transfers in the affected PIPE queue
|
|
will be started until either:
|
|
.Bl -tag -width "X"
|
|
.It 1
|
|
The failing USB transfer is stopped using "usbd_transfer_stop()".
|
|
.It 2
|
|
The failing USB transfer performs a successful transfer.
|
|
.El
|
|
The purpose of this flag is to avoid races when multiple transfers are
|
|
queued for execution on an USB endpoint, and the first executing
|
|
transfer fails leading to the need for clearing of stall for
|
|
example.
|
|
.
|
|
In this case this flag is used to prevent the following USB transfers
|
|
from being executed at the same time the clear-stall command is
|
|
executed on the USB control endpoint.
|
|
.
|
|
This flag can be changed during operation.
|
|
.Pp
|
|
"BOF" is short for "Block On Failure".
|
|
.Pp
|
|
NOTE: This flag should be set on all BULK and INTERRUPT USB transfers
|
|
which use an endpoint that can be shared between userland and kernel.
|
|
.
|
|
.
|
|
.It proxy_buffer
|
|
Setting this flag will cause that the total buffer size will be
|
|
rounded up to the nearest atomic hardware transfer size.
|
|
.
|
|
The maximum data length of any USB transfer is always stored in the
|
|
"xfer->max_data_length".
|
|
.
|
|
For control transfers the USB kernel will allocate additional space
|
|
for the 8-bytes of SETUP header.
|
|
.
|
|
These 8-bytes are not counted by the "xfer->max_data_length"
|
|
variable.
|
|
.
|
|
This flag cannot be changed during operation.
|
|
.
|
|
.
|
|
.It ext_buffer
|
|
Setting this flag will cause that no data buffer will be
|
|
allocated.
|
|
.
|
|
Instead the USB client must supply a data buffer.
|
|
.
|
|
This flag cannot be changed during operation.
|
|
.
|
|
.
|
|
.It manual_status
|
|
Setting this flag prevents an USB STATUS stage to be appended to the
|
|
end of the USB control transfer.
|
|
.
|
|
If no control data is transferred this flag must be cleared.
|
|
.
|
|
Else an error will be returned to the USB callback.
|
|
.
|
|
This flag is mostly useful for the USB device side.
|
|
.
|
|
This flag can be changed during operation.
|
|
.
|
|
.
|
|
.It no_pipe_ok
|
|
Setting this flag causes the USB_ERR_NO_PIPE error to be ignored.
|
|
This flag cannot be changed during operation.
|
|
.
|
|
.
|
|
.It stall_pipe
|
|
.Bl -tag -width "Device Side Mode"
|
|
.It Device Side Mode
|
|
Setting this flag will cause STALL pids to be sent to the endpoint
|
|
belonging to this transfer before the transfer is started.
|
|
.
|
|
The transfer is started at the moment the host issues a clear-stall
|
|
command on the STALL'ed endpoint.
|
|
.
|
|
This flag can be changed during operation.
|
|
.It Host Side Mode
|
|
Setting this flag will cause a clear-stall control request to be
|
|
executed on the endpoint before the USB transfer is started.
|
|
.El
|
|
.Pp
|
|
If this flag is changed outside the USB callback function you have to
|
|
use the "usbd_xfer_set_stall()" and "usbd_transfer_clear_stall()"
|
|
functions! This flag is automatically cleared after that the stall or
|
|
clear stall has been executed.
|
|
.
|
|
.It pre_scale_frames
|
|
If this flag is set the number of frames specified is assumed to give the buffering time in milliseconds instead of frames.
|
|
During transfer setup the frames field is pre scaled with the corresponding value for the endpoint and rounded to the nearest number of frames greater than zero.
|
|
This option only has effect for ISOCHRONOUS transfers.
|
|
.El
|
|
.Pp
|
|
.Fa bufsize
|
|
field sets the total buffer size in bytes.
|
|
.
|
|
If this field is zero, "wMaxPacketSize" will be used, multiplied by
|
|
the "frames" field if the transfer type is ISOCHRONOUS.
|
|
.
|
|
This is useful for setting up interrupt pipes.
|
|
.
|
|
This field is mandatory.
|
|
.Pp
|
|
NOTE: For control transfers "bufsize" includes the length of the
|
|
request structure.
|
|
.
|
|
.Pp
|
|
.Fa callback
|
|
pointer sets the USB callback.
|
|
This field is mandatory.
|
|
.
|
|
.
|
|
.Sh USB LINUX COMPAT LAYER
|
|
The
|
|
.Nm usb
|
|
module supports the Linux USB API.
|
|
.
|
|
.
|
|
.Sh SEE ALSO
|
|
.Xr libusb 3 ,
|
|
.Xr usb 4 ,
|
|
.Xr usbconfig 8
|
|
.Sh STANDARDS
|
|
The
|
|
.Nm usb
|
|
module complies with the USB 2.0 standard.
|
|
.Sh HISTORY
|
|
The
|
|
.Nm usb
|
|
module has been inspired by the NetBSD USB stack initially written by
|
|
Lennart Augustsson.
|
|
The
|
|
.Nm usb
|
|
module was written by
|
|
.An Hans Petter Selasky Aq Mt hselasky@FreeBSD.org .
|