USB_EP_SET_HALT(9) Kernel Mode Gadget API USB_EP_SET_HALT(9)NAME
usb_ep_set_halt - sets the endpoint halt feature.
SYNOPSIS
int usb_ep_set_halt(struct usb_ep * ep);
ARGUMENTS
ep
the non-isochronous endpoint being stalled
DESCRIPTION
Use this to stall an endpoint, perhaps as an error report. Except for control endpoints, the endpoint stays halted (will not stream any
data) until the host clears this feature; drivers may need to empty the endpoint's request queue first, to make sure no inappropriate
transfers happen.
Note that while an endpoint CLEAR_FEATURE will be invisible to the gadget driver, a SET_INTERFACE will not be. To reset endpoints for the
current altsetting, see usb_ep_clear_halt. When switching altsettings, it's simplest to use usb_ep_enable or usb_ep_disable for the
endpoints.
Returns zero, or a negative error code. On success, this call sets underlying hardware state that blocks data transfers. Attempts to halt
IN endpoints will fail (returning -EAGAIN) if any transfer requests are still queued, or if the controller hardware (usually a FIFO) still
holds bytes that the host hasn't collected.
AUTHOR
David Brownell <dbrownell@users.sourceforge.net>
Author.
COPYRIGHT Kernel Hackers Manual 3.10 June 2014 USB_EP_SET_HALT(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)