47 lines
1.8 KiB
C
47 lines
1.8 KiB
C
/*
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* This file holds USB constants and structures that are needed for
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* USB device APIs. These are used by the USB device model, which is
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* defined in chapter 9 of the USB 2.0 specification and in the
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* Wireless USB 1.0 (spread around). Linux has several APIs in C that
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* need these:
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*
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* - the master/host side Linux-USB kernel driver API;
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* - the "usbfs" user space API; and
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* - the Linux "gadget" slave/device/peripheral side driver API.
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*
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* USB 2.0 adds an additional "On The Go" (OTG) mode, which lets systems
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* act either as a USB master/host or as a USB slave/device. That means
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* the master and slave side APIs benefit from working well together.
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*
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* There's also "Wireless USB", using low power short range radios for
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* peripheral interconnection but otherwise building on the USB framework.
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*
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* Note all descriptors are declared '__attribute__((packed))' so that:
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*
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* [a] they never get padded, either internally (USB spec writers
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* probably handled that) or externally;
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*
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* [b] so that accessing bigger-than-a-bytes fields will never
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* generate bus errors on any platform, even when the location of
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* its descriptor inside a bundle isn't "naturally aligned", and
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*
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* [c] for consistency, removing all doubt even when it appears to
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* someone that the two other points are non-issues for that
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* particular descriptor type.
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*/
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#ifndef __LINUX_USB_CH9_H
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#define __LINUX_USB_CH9_H
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#include <uapi/linux/usb/ch9.h>
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/**
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* usb_speed_string() - Returns human readable-name of the speed.
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* @speed: The speed to return human-readable name for. If it's not
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* any of the speeds defined in usb_device_speed enum, string for
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* USB_SPEED_UNKNOWN will be returned.
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*/
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extern const char *usb_speed_string(enum usb_device_speed speed);
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#endif /* __LINUX_USB_CH9_H */
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