STRUCT USB_EP(9) Kernel Mode Gadget API STRUCT USB_EP(9)NAME
struct_usb_ep - device side representation of USB endpoint
SYNOPSIS
struct usb_ep {
void * driver_data;
const char * name;
const struct usb_ep_ops * ops;
struct list_head ep_list;
unsigned maxpacket:16;
unsigned max_streams:16;
unsigned mult:2;
unsigned maxburst:5;
u8 address;
const struct usb_endpoint_descriptor * desc;
const struct usb_ss_ep_comp_descriptor * comp_desc;
};
MEMBERS
driver_data
for use by the gadget driver.
name
identifier for the endpoint, such as "ep-a" or "ep9in-bulk"
ops
Function pointers used to access hardware-specific operations.
ep_list
the gadget's ep_list holds all of its endpoints
maxpacket
The maximum packet size used on this endpoint. The initial value can sometimes be reduced (hardware allowing), according to the
endpoint descriptor used to configure the endpoint.
max_streams
The maximum number of streams supported by this EP (0 - 16, actual number is 2^n)
mult
multiplier, 'mult' value for SS Isoc EPs
maxburst
the maximum number of bursts supported by this EP (for usb3)
address
used to identify the endpoint when finding descriptor that matches connection speed
desc
endpoint descriptor. This pointer is set before the endpoint is enabled and remains valid until the endpoint is disabled.
comp_desc
In case of SuperSpeed support, this is the endpoint companion descriptor that is used to configure the endpoint
DESCRIPTION
the bus controller driver lists all the general purpose endpoints in gadget->ep_list. the control endpoint (gadget->ep0) is not in that
list, and is accessed only in response to a driver setup callback.
AUTHOR
David Brownell <dbrownell@users.sourceforge.net>
Author.
COPYRIGHT Kernel Hackers Manual 3.10 June 2014 STRUCT USB_EP(9)
Check Out this Related Man Page
STRUCT USB_GADGET_DR(9) Kernel Mode Gadget API STRUCT USB_GADGET_DR(9)NAME
struct_usb_gadget_driver - driver for usb 'slave' devices
SYNOPSIS
struct usb_gadget_driver {
char * function;
enum usb_device_speed speed;
int (* bind) (struct usb_gadget *);
void (* unbind) (struct usb_gadget *);
int (* setup) (struct usb_gadget *,const struct usb_ctrlrequest *);
void (* disconnect) (struct usb_gadget *);
void (* suspend) (struct usb_gadget *);
void (* resume) (struct usb_gadget *);
struct device_driver driver;
};
MEMBERS
function
String describing the gadget's function
speed
Highest speed the driver handles.
bind
Invoked when the driver is bound to a gadget, usually after registering the driver. At that point, ep0 is fully initialized, and
ep_list holds the currently-available endpoints. Called in a context that permits sleeping.
unbind
Invoked when the driver is unbound from a gadget, usually from rmmod (after a disconnect is reported). Called in a context that permits
sleeping.
setup
Invoked for ep0 control requests that aren't handled by the hardware level driver. Most calls must be handled by the gadget driver,
including descriptor and configuration management. The 16 bit members of the setup data are in USB byte order. Called in_interrupt;
this may not sleep. Driver queues a response to ep0, or returns negative to stall.
disconnect
Invoked after all transfers have been stopped, when the host is disconnected. May be called in_interrupt; this may not sleep. Some
devices can't detect disconnect, so this might not be called except as part of controller shutdown.
suspend
Invoked on USB suspend. May be called in_interrupt.
resume
Invoked on USB resume. May be called in_interrupt.
driver
Driver model state for this driver.
DESCRIPTION
Devices are disabled till a gadget driver successfully binds, which means the driver will handle setup requests needed to enumerate (and
meet "chapter 9" requirements) then do some useful work.
If gadget->is_otg is true, the gadget driver must provide an OTG descriptor during enumeration, or else fail the bind call. In such cases,
no USB traffic may flow until both bind returns without having called usb_gadget_disconnect, and the USB host stack has initialized.
Drivers use hardware-specific knowledge to configure the usb hardware. endpoint addressing is only one of several hardware characteristics
that are in descriptors the ep0 implementation returns from setup calls.
Except for ep0 implementation, most driver code shouldn't need change to run on top of different usb controllers. It'll use endpoints set
up by that ep0 implementation.
The usb controller driver handles a few standard usb requests. Those include set_address, and feature flags for devices, interfaces, and
endpoints (the get_status, set_feature, and clear_feature requests).
Accordingly, the driver's setup callback must always implement all get_descriptor requests, returning at least a device descriptor and a
configuration descriptor. Drivers must make sure the endpoint descriptors match any hardware constraints. Some hardware also constrains
other descriptors. (The pxa250 allows only configurations 1, 2, or 3).
The driver's setup callback must also implement set_configuration, and should also implement set_interface, get_configuration, and
get_interface. Setting a configuration (or interface) is where endpoints should be activated or (config 0) shut down.
(Note that only the default control endpoint is supported. Neither hosts nor devices generally support control traffic except to ep0.)
Most devices will ignore USB suspend/resume operations, and so will not provide those callbacks. However, some may need to change modes
when the host is not longer directing those activities. For example, local controls (buttons, dials, etc) may need to be re-enabled since
the (remote) host can't do that any longer; or an error state might be cleared, to make the device behave identically whether or not power
is maintained.
AUTHOR
David Brownell <dbrownell@users.sourceforge.net>
Author.
COPYRIGHT Kernel Hackers Manual 2.6. July 2010 STRUCT USB_GADGET_DR(9)