1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * This file holds USB constants and structures that are needed for
4 * USB device APIs. These are used by the USB device model, which is
5 * defined in chapter 9 of the USB 2.0 specification and in the
6 * Wireless USB 1.0 (spread around). Linux has several APIs in C that
7 * need these:
8 *
9 * - the master/host side Linux-USB kernel driver API;
10 * - the "usbfs" user space API; and
11 * - the Linux "gadget" slave/device/peripheral side driver API.
12 *
13 * USB 2.0 adds an additional "On The Go" (OTG) mode, which lets systems
14 * act either as a USB master/host or as a USB slave/device. That means
15 * the master and slave side APIs benefit from working well together.
16 *
17 * There's also "Wireless USB", using low power short range radios for
18 * peripheral interconnection but otherwise building on the USB framework.
19 *
20 * Note all descriptors are declared '__attribute__((packed))' so that:
21 *
22 * [a] they never get padded, either internally (USB spec writers
23 * probably handled that) or externally;
24 *
25 * [b] so that accessing bigger-than-a-bytes fields will never
26 * generate bus errors on any platform, even when the location of
27 * its descriptor inside a bundle isn't "naturally aligned", and
28 *
29 * [c] for consistency, removing all doubt even when it appears to
30 * someone that the two other points are non-issues for that
31 * particular descriptor type.
32 */
33#ifndef __LINUX_USB_CH9_H
34#define __LINUX_USB_CH9_H
35
36#include <linux/device.h>
37#include <uapi/linux/usb/ch9.h>
38
39/**
40 * usb_speed_string() - Returns human readable-name of the speed.
41 * @speed: The speed to return human-readable name for. If it's not
42 * any of the speeds defined in usb_device_speed enum, string for
43 * USB_SPEED_UNKNOWN will be returned.
44 */
45extern const char *usb_speed_string(enum usb_device_speed speed);
46
47/**
48 * usb_get_maximum_speed - Get maximum requested speed for a given USB
49 * controller.
50 * @dev: Pointer to the given USB controller device
51 *
52 * The function gets the maximum speed string from property "maximum-speed",
53 * and returns the corresponding enum usb_device_speed.
54 */
55extern enum usb_device_speed usb_get_maximum_speed(struct device *dev);
56
57/**
58 * usb_state_string - Returns human readable name for the state.
59 * @state: The state to return a human-readable name for. If it's not
60 * any of the states devices in usb_device_state_string enum,
61 * the string UNKNOWN will be returned.
62 */
63extern const char *usb_state_string(enum usb_device_state state);
64
65#endif /* __LINUX_USB_CH9_H */
66