LXR linux/include/linux/usb/ch9.h

   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 <linux/device.h>
  36#include <uapi/linux/usb/ch9.h>
  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 * usb_get_maximum_speed - Get maximum requested speed for a given USB
  48 * controller.
  49 * @dev: Pointer to the given USB controller device
  50 *
  51 * The function gets the maximum speed string from property "maximum-speed",
  52 * and returns the corresponding enum usb_device_speed.
  53 */
  54extern enum usb_device_speed usb_get_maximum_speed(struct device *dev);
  55
  56/**
  57 * usb_state_string - Returns human readable name for the state.
  58 * @state: The state to return a human-readable name for. If it's not
  59 *      any of the states devices in usb_device_state_string enum,
  60 *      the string UNKNOWN will be returned.
  61 */
  62extern const char *usb_state_string(enum usb_device_state state);
  63
  64#endif /* __LINUX_USB_CH9_H */
  65