1STRUCT USB_CONFIGURA(9)     Kernel Mode Gadget API     STRUCT USB_CONFIGURA(9)
2
3
4

NAME

6       struct_usb_configuration - represents one gadget configuration
7

SYNOPSIS

9       struct usb_configuration {
10         const char * label;
11         struct usb_gadget_strings ** strings;
12         const struct usb_descriptor_header ** descriptors;
13         void (* unbind) (struct usb_configuration *);
14         int (* setup) (struct usb_configuration *,const struct usb_ctrlrequest *);
15         u8 bConfigurationValue;
16         u8 iConfiguration;
17         u8 bmAttributes;
18         u16 MaxPower;
19         struct usb_composite_dev * cdev;
20       };
21

MEMBERS

23       label
24           For diagnostics, describes the configuration.
25
26       strings
27           Tables of strings, keyed by identifiers assigned during bind() and
28           by language IDs provided in control requests.
29
30       descriptors
31           Table of descriptors preceding all function descriptors. Examples
32           include OTG and vendor-specific descriptors.
33
34       unbind
35           Reverses bind; called as a side effect of unregistering the driver
36           which added this configuration.
37
38       setup
39           Used to delegate control requests that aren't handled by standard
40           device infrastructure or directed at a specific interface.
41
42       bConfigurationValue
43           Copied into configuration descriptor.
44
45       iConfiguration
46           Copied into configuration descriptor.
47
48       bmAttributes
49           Copied into configuration descriptor.
50
51       MaxPower
52           Power consumtion in mA. Used to compute bMaxPower in the
53           configuration descriptor after considering the bus speed.
54
55       cdev
56           assigned by usb_add_config() before calling bind(); this is the
57           device associated with this configuration.
58

DESCRIPTION

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

AUTHOR

84       David Brownell <dbrownell@users.sourceforge.net>
85           Author.
86

88Kernel Hackers Manual 3.10         June 2019           STRUCT USB_CONFIGURA(9)
Impressum