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