1STRUCT USB_CONFIGURA(9)     Kernel Mode Gadget API     STRUCT USB_CONFIGURA(9)
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NAME

6       struct_usb_configuration - represents one gadget configuration
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SYNOPSIS

9       struct usb_configuration {
10         const char * label;
11         struct usb_gadget_strings ** strings;
12         const struct usb_descriptor_header ** descriptors;
13         int (* bind) (struct usb_configuration *);
14         void (* unbind) (struct usb_configuration *);
15         int (* setup) (struct usb_configuration *,const struct usb_ctrlrequest *);
16         u8 bConfigurationValue;
17         u8 iConfiguration;
18         u8 bmAttributes;
19         u8 bMaxPower;
20         struct usb_composite_dev * cdev;
21       };
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MEMBERS

24       label
25           For diagnostics, describes the configuration.
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27       strings
28           Tables of strings, keyed by identifiers assigned during bind() and
29           by language IDs provided in control requests.
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31       descriptors
32           Table of descriptors preceding all function descriptors. Examples
33           include OTG and vendor-specific descriptors.
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35       bind
36           Called from usb_add_config() to allocate resources unique to this
37           configuration and to call usb_add_function() for each function
38           used.
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40       unbind
41           Reverses bind; called as a side effect of unregistering the driver
42           which added this configuration.
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44       setup
45           Used to delegate control requests that aren´t handled by standard
46           device infrastructure or directed at a specific interface.
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48       bConfigurationValue
49           Copied into configuration descriptor.
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51       iConfiguration
52           Copied into configuration descriptor.
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54       bmAttributes
55           Copied into configuration descriptor.
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57       bMaxPower
58           Copied into configuration descriptor.
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60       cdev
61           assigned by usb_add_config() before calling bind(); this is the
62           device associated with this configuration.
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DESCRIPTION

65       Configurations are building blocks for gadget drivers structured around
66       function drivers. Simple USB gadgets require only one function and one
67       configuration, and handle dual-speed hardware by always providing the
68       same functionality. Slightly more complex gadgets may have more than
69       one single-function configuration at a given speed; or have
70       configurations that only work at one speed.
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72       Composite devices are, by definition, ones with configurations which
73       include more than one function.
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75       The lifecycle of a usb_configuration includes allocation,
76       initialization of the fields described above, and calling
77       usb_add_config() to set up internal data and bind it to a specific
78       device. The configuration´s bind() method is then used to initialize
79       all the functions and then call usb_add_function() for them.
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81       Those functions would normally be independant of each other, but that´s
82       not mandatory. CDC WMC devices are an example where functions often
83       depend on other functions, with some functions subsidiary to others.
84       Such interdependency may be managed in any way, so long as all of the
85       descriptors complete by the time the composite driver returns from its
86       bind routine.
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AUTHOR

89       David Brownell <dbrownell@users.sourceforge.net>
90           Author.
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93Kernel Hackers Manual 2.6.         June 2019           STRUCT USB_CONFIGURA(9)
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