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#include <linux/module.h>
#include <linux/string.h>
#include <linux/bitops.h>
#include <linux/slab.h>
#include <linux/log2.h>
#include <linux/usb.h>
#include <linux/wait.h>
#include <linux/usb/hcd.h>
#include <linux/scatterlist.h>
#define to_urb(d) container_of(d, struct urb, kref)
static void urb_destroy(struct kref *kref)
{
struct urb *urb = to_urb(kref);
if (urb->transfer_flags & URB_FREE_BUFFER)
kfree(urb->transfer_buffer);
kfree(urb);
}
/**
* usb_init_urb - initializes a urb so that it can be used by a USB driver
* @urb: pointer to the urb to initialize
*
* Initializes a urb so that the USB subsystem can use it properly.
*
* If a urb is created with a call to usb_alloc_urb() it is not
* necessary to call this function. Only use this if you allocate the
* space for a struct urb on your own. If you call this function, be
* careful when freeing the memory for your urb that it is no longer in
* use by the USB core.
*
* Only use this function if you _really_ understand what you are doing.
*/
void usb_init_urb(struct urb *urb)
{
if (urb) {
memset(urb, 0, sizeof(*urb));
kref_init(&urb->kref);
INIT_LIST_HEAD(&urb->anchor_list);
}
}
EXPORT_SYMBOL_GPL(usb_init_urb);
/**
* usb_alloc_urb - creates a new urb for a USB driver to use
* @iso_packets: number of iso packets for this urb
* @mem_flags: the type of memory to allocate, see kmalloc() for a list of
* valid options for this.
*
* Creates an urb for the USB driver to use, initializes a few internal
* structures, increments the usage counter, and returns a pointer to it.
*
* If the driver want to use this urb for interrupt, control, or bulk
* endpoints, pass '0' as the number of iso packets.
*
* The driver must call usb_free_urb() when it is finished with the urb.
*
* Return: A pointer to the new urb, or %NULL if no memory is available.
*/
struct urb *usb_alloc_urb(int iso_packets, gfp_t mem_flags)
{
struct urb *urb;
urb = kmalloc(sizeof(struct urb) +
iso_packets * sizeof(struct usb_iso_packet_descriptor),
mem_flags);
if (!urb) {
printk(KERN_ERR "alloc_urb: kmalloc failed\n");
return NULL;
}
usb_init_urb(urb);
return urb;
}
EXPORT_SYMBOL_GPL(usb_alloc_urb);
/**
* usb_free_urb - frees the memory used by a urb when all users of it are finished
* @urb: pointer to the urb to free, may be NULL
*
* Must be called when a user of a urb is finished with it. When the last user
* of the urb calls this function, the memory of the urb is freed.
*
* Note: The transfer buffer associated with the urb is not freed unless the
* URB_FREE_BUFFER transfer flag is set.
*/
void usb_free_urb(struct urb *urb)
{
if (urb)
kref_put(&urb->kref, urb_destroy);
}
EXPORT_SYMBOL_GPL(usb_free_urb);
/**
* usb_get_urb - increments the reference count of the urb
* @urb: pointer to the urb to modify, may be NULL
*
* This must be called whenever a urb is transferred from a device driver to a
* host controller driver. This allows proper reference counting to happen
* for urbs.
*
* Return: A pointer to the urb with the incremented reference counter.
*/
struct urb *usb_get_urb(struct urb *urb)
{
if (urb)
kref_get(&urb->kref);
return urb;
}
EXPORT_SYMBOL_GPL(usb_get_urb);
/**
* usb_anchor_urb - anchors an URB while it is processed
* @urb: pointer to the urb to anchor
* @anchor: pointer to the anchor
*
* This can be called to have access to URBs which are to be executed
* without bothering to track them
*/
void usb_anchor_urb(struct urb *urb, struct usb_anchor *anchor)
{
unsigned long flags;
spin_lock_irqsave(&anchor->lock, flags);
usb_get_urb(urb);
list_add_tail(&urb->anchor_list, &anchor->urb_list);
urb->anchor = anchor;
if (unlikely(anchor->poisoned)) {
atomic_inc(&urb->reject);
}
spin_unlock_irqrestore(&anchor->lock, flags);
}
EXPORT_SYMBOL_GPL(usb_anchor_urb);
static int usb_anchor_check_wakeup(struct usb_anchor *anchor)
{
return atomic_read(&anchor->suspend_wakeups) == 0 &&
list_empty(&anchor->urb_list);
}
/* Callers must hold anchor->lock */
static void __usb_unanchor_urb(struct urb *urb, struct usb_anchor *anchor)
{
urb->anchor = NULL;
list_del(&urb->anchor_list);
usb_put_urb(urb);
if (usb_anchor_check_wakeup(anchor))
wake_up(&anchor->wait);
}
/**
* usb_unanchor_urb - unanchors an URB
* @urb: pointer to the urb to anchor
*
* Call this to stop the system keeping track of this URB
*/
void usb_unanchor_urb(struct urb *urb)
{
unsigned long flags;
struct usb_anchor *anchor;
if (!urb)
return;
anchor = urb->anchor;
if (!anchor)
return;
spin_lock_irqsave(&anchor->lock, flags);
/*
* At this point, we could be competing with another thread which
* has the same intention. To protect the urb from being unanchored
* twice, only the winner of the race gets the job.
*/
if (likely(anchor == urb->anchor))
__usb_unanchor_urb(urb, anchor);
spin_unlock_irqrestore(&anchor->lock, flags);
}
EXPORT_SYMBOL_GPL(usb_unanchor_urb);
/*-------------------------------------------------------------------*/
/**
* usb_submit_urb - issue an asynchronous transfer request for an endpoint
* @urb: pointer to the urb describing the request
* @mem_flags: the type of memory to allocate, see kmalloc() for a list
* of valid options for this.
*
* This submits a transfer request, and transfers control of the URB
* describing that request to the USB subsystem. Request completion will
* be indicated later, asynchronously, by calling the completion handler.
* The three types of completion are success, error, and unlink
* (a software-induced fault, also called "request cancellation").
*
* URBs may be submitted in interrupt context.
*
* The caller must have correctly initialized the URB before submitting
* it. Functions such as usb_fill_bulk_urb() and usb_fill_control_urb() are
* available to ensure that most fields are correctly initialized, for
* the particular kind of transfer, although they will not initialize
* any transfer flags.
*
* If the submission is successful, the complete() callback from the URB
* will be called exactly once, when the USB core and Host Controller Driver
* (HCD) are finished with the URB. When the completion function is called,
* control of the URB is returned to the device driver which issued the
* request. The completion handler may then immediately free or reuse that
* URB.
*
* With few exceptions, USB device drivers should never access URB fields
* provided by usbcore or the HCD until its complete() is called.
* The exceptions relate to periodic transfer scheduling. For both
* interrupt and isochronous urbs, as part of successful URB submission
* urb->interval is modified to reflect the actual transfer period used
* (normally some power of two units). And for isochronous urbs,
* urb->start_frame is modified to reflect when the URB's transfers were
* scheduled to start.
*
* Not all isochronous transfer scheduling policies will work, but most
* host controller drivers shoul
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