usbd_topology(), usbd_topology_ext()

Get the USB bus physical topology

Synopsis:

#include <sys/usbdi.h>

int usbd_topology( struct usbd_connection *connection,
                   usbd_bus_topology_t *tp )

int usbd_topology_ext( struct usbd_connection *connection,
                       _uint8 busno,
                       usbd_bus_topology_t *tp )

Arguments:

connection

An opaque handle that identifies the USB stack, obtained by calling usbd_connect().

bus

(usbd_topology_ext() only) The index of the bus that you want the topology for.

tp

A pointer to a usbd_bus_topology_t data structure that this function fills in; see below.

Library:

libusbdi

Description:

You can use the usbd_topology() or usbd_topology_ext() function to get the USB bus physical topology.

---

For more information on USB bus topology, see sections 4.1.1 and 5.2.3 in the USB Specification v1.1.

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If your system has more than one bus, you can call usbd_topology_ext() to get information about a specific one. The usbd_topology() function gets information about the first bus; calling it is the same as calling usbd_topology() with a bus argument of 0.

The usbd_bus_topology_t structure is defined as follows:

typedef struct usbd_port_attachment {
    _uint8  upstream_devno;
    _uint8  upstream_port;
    _uint8  upstream_port_speed;
    _uint8  upstream_hc;
    _uint8  _reserved[4];
} usbd_port_attachment_t;

typedef struct usbd_bus_topology {
    usbd_port_attachment_t    ports[64];
} usbd_bus_topology_t;

The structure contains an array of usb_port_attachment_t structures, one per device. The usb_port_attachment_t structure contains at least the following:

upstream_devno

The device number of the upstream hub (0 if it's a root port).

upstream_port

The port number the device is connected to.

upstream_port_speed

The port speed that the device is operating at; one of the following:

• 0 — full
• 1 — low
• 2 — high

upstream_hc

The bus or host controller that the device is connected to.

---

The upstream_devno field will contain a value other than 0xff to indicate a valid attachment.

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Returns:

EOK

Success.

ENODEV

The device was removed.

Classification:

QNX Neutrino, QNX 4

See also:

usbd_connect()