blob: 081796726b951bf449b8b827b970cf7eec1b8571 [file] [log] [blame]
#include <linux/config.h>
#include <linux/module.h>
#include <linux/string.h>
#include <linux/bitops.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/usb.h>
#include "hcd.h"
#define to_urb(d) container_of(d, struct urb, kref)
static void urb_destroy(struct kref *kref)
struct urb *urb = to_urb(kref);
* 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));
* 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, incrementes the usage counter, and returns a pointer to it.
* If no memory is available, NULL is returned.
* 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.
struct urb *usb_alloc_urb(int iso_packets, gfp_t mem_flags)
struct urb *urb;
urb = (struct urb *)kmalloc(sizeof(struct urb) +
iso_packets * sizeof(struct usb_iso_packet_descriptor),
if (!urb) {
err("alloc_urb: kmalloc failed");
return NULL;
return 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, that must be
* done elsewhere.
void usb_free_urb(struct urb *urb)
if (urb)
kref_put(&urb->kref, urb_destroy);
* 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.
* A pointer to the urb with the incremented reference counter is returned.
struct urb * usb_get_urb(struct urb *urb)
if (urb)
return 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.
* Successful submissions return 0; otherwise this routine returns a
* negative error number. 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 should easily handle ISO
* queues going from now until 10-200 msec into the future.
* For control endpoints, the synchronous usb_control_msg() call is
* often used (in non-interrupt context) instead of this call.
* That is often used through convenience wrappers, for the requests
* that are standardized in the USB 2.0 specification. For bulk
* endpoints, a synchronous usb_bulk_msg() call is available.
* Request Queuing:
* URBs may be submitted to endpoints before previous ones complete, to
* minimize the impact of interrupt latencies and system overhead on data
* throughput. With that queuing policy, an endpoint's queue would never
* be empty. This is required for continuous isochronous data streams,
* and may also be required for some kinds of interrupt transfers. Such
* queuing also maximizes bandwidth utilization by letting USB controllers
* start work on later requests before driver software has finished the
* completion processing for earlier (successful) requests.
* As of Linux 2.6, all USB endpoint transfer queues support depths greater
* than one. This was previously a HCD-specific behavior, except for ISO
* transfers. Non-isochronous endpoint queues are inactive during cleanup
* after faults (transfer errors or cancellation).
* Reserved Bandwidth Transfers:
* Periodic transfers (interrupt or isochronous) are performed repeatedly,
* using the interval specified in the urb. Submitting the first urb to
* the endpoint reserves the bandwidth necessary to make those transfers.
* If the USB subsystem can't allocate sufficient bandwidth to perform
* the periodic request, submitting such a periodic request should fail.
* Device drivers must explicitly request that repetition, by ensuring that
* some URB is always on the endpoint's queue (except possibly for short
* periods during completion callacks). When there is no longer an urb
* queued, the endpoint's bandwidth reservation is canceled. This means
* drivers can use their completion handlers to ensure they keep bandwidth
* they need, by reinitializing and resubmitting the just-completed urb
* until the driver longer needs that periodic bandwidth.
* Memory Flags:
* The general rules for how to decide which mem_flags to use
* are the same as for kmalloc. There are four
* different possible values; GFP_KERNEL, GFP_NOFS, GFP_NOIO and
* GFP_NOFS is not ever used, as it has not been implemented yet.
* GFP_ATOMIC is used when
* (a) you are inside a completion handler, an interrupt, bottom half,
* tasklet or timer, or
* (b) you are holding a spinlock or rwlock (does not apply to
* semaphores), or
* (c) current->state != TASK_RUNNING, this is the case only after
* you've changed it.
* GFP_NOIO is used in the block io path and error handling of storage
* devices.
* All other situations use GFP_KERNEL.
* Some more specific rules for mem_flags can be inferred, such as
* (1) start_xmit, timeout, and receive methods of network drivers must
* use GFP_ATOMIC (they are called with a spinlock held);
* (2) queuecommand methods of scsi drivers must use GFP_ATOMIC (also
* called with a spinlock held);
* (3) If you use a kernel thread with a network driver you must use
* GFP_NOIO, unless (b) or (c) apply;
* (4) after you have done a down() you can use GFP_KERNEL, unless (b) or (c)
* apply or your are in a storage driver's block io path;
* (5) USB probe and disconnect can use GFP_KERNEL unless (b) or (c) apply; and
* (6) changing firmware on a running storage or net device uses
* GFP_NOIO, unless b) or c) apply
int usb_submit_urb(struct urb *urb, gfp_t mem_flags)
int pipe, temp, max;
struct usb_device *dev;
struct usb_operations *op;
int is_out;
if (!urb || urb->hcpriv || !urb->complete)
return -EINVAL;
if (!(dev = urb->dev) ||
(dev->state < USB_STATE_DEFAULT) ||
(!dev->bus) || (dev->devnum <= 0))
return -ENODEV;
if (dev->bus->controller->power.power_state.event != PM_EVENT_ON
|| dev->state == USB_STATE_SUSPENDED)
if (!(op = dev->bus->op) || !op->submit_urb)
return -ENODEV;
urb->status = -EINPROGRESS;
urb->actual_length = 0;
urb->bandwidth = 0;
/* Lots of sanity checks, so HCDs can rely on clean data
* and don't need to duplicate tests
pipe = urb->pipe;
temp = usb_pipetype (pipe);
is_out = usb_pipeout (pipe);
if (!usb_pipecontrol (pipe) && dev->state < USB_STATE_CONFIGURED)
return -ENODEV;
/* FIXME there should be a sharable lock protecting us against
* config/altsetting changes and disconnects, kicking in here.
* (here == before maxpacket, and eventually endpoint type,
* checks get made.)
max = usb_maxpacket (dev, pipe, is_out);
if (max <= 0) {
"bogus endpoint ep%d%s in %s (bad maxpacket %d)\n",
usb_pipeendpoint (pipe), is_out ? "out" : "in",
__FUNCTION__, max);
return -EMSGSIZE;
/* periodic transfers limit size per frame/uframe,
* but drivers only control those sizes for ISO.
* while we're checking, initialize return status.
if (temp == PIPE_ISOCHRONOUS) {
int n, len;
/* "high bandwidth" mode, 1-3 packets/uframe? */
if (dev->speed == USB_SPEED_HIGH) {
int mult = 1 + ((max >> 11) & 0x03);
max &= 0x07ff;
max *= mult;
if (urb->number_of_packets <= 0)
return -EINVAL;
for (n = 0; n < urb->number_of_packets; n++) {
len = urb->iso_frame_desc [n].length;
if (len < 0 || len > max)
return -EMSGSIZE;
urb->iso_frame_desc [n].status = -EXDEV;
urb->iso_frame_desc [n].actual_length = 0;
/* the I/O buffer must be mapped/unmapped, except when length=0 */
if (urb->transfer_buffer_length < 0)
return -EMSGSIZE;
#ifdef DEBUG
/* stuff that drivers shouldn't do, but which shouldn't
* cause problems in HCDs if they get it wrong.
unsigned int orig_flags = urb->transfer_flags;
unsigned int allowed;
/* enforce simple/standard policy */
switch (temp) {
if (is_out)
allowed |= URB_ZERO_PACKET;
allowed |= URB_NO_FSBR; /* only affects UHCI */
default: /* all non-iso endpoints */
if (!is_out)
allowed |= URB_SHORT_NOT_OK;
allowed |= URB_ISO_ASAP;
urb->transfer_flags &= allowed;
/* fail if submitter gave bogus flags */
if (urb->transfer_flags != orig_flags) {
err ("BOGUS urb flags, %x --> %x",
orig_flags, urb->transfer_flags);
return -EINVAL;
* Force periodic transfer intervals to be legal values that are
* a power of two (so HCDs don't need to).
* FIXME want bus->{intr,iso}_sched_horizon values here. Each HC
* supports different values... this uses EHCI/UHCI defaults (and
* EHCI can use smaller non-default values).
switch (temp) {
/* too small? */
if (urb->interval <= 0)
return -EINVAL;
/* too big? */
switch (dev->speed) {
case USB_SPEED_HIGH: /* units are microframes */
// NOTE usb handles 2^15
if (urb->interval > (1024 * 8))
urb->interval = 1024 * 8;
temp = 1024 * 8;
case USB_SPEED_FULL: /* units are frames/msec */
if (temp == PIPE_INTERRUPT) {
if (urb->interval > 255)
return -EINVAL;
// NOTE ohci only handles up to 32
temp = 128;
} else {
if (urb->interval > 1024)
urb->interval = 1024;
// NOTE usb and ohci handle up to 2^15
temp = 1024;
return -EINVAL;
/* power of two? */
while (temp > urb->interval)
temp >>= 1;
urb->interval = temp;
return op->submit_urb (urb, mem_flags);
* usb_unlink_urb - abort/cancel a transfer request for an endpoint
* @urb: pointer to urb describing a previously submitted request,
* may be NULL
* This routine cancels an in-progress request. URBs complete only
* once per submission, and may be canceled only once per submission.
* Successful cancellation means the requests's completion handler will
* be called with a status code indicating that the request has been
* canceled (rather than any other code) and will quickly be removed
* from host controller data structures.
* This request is always asynchronous.
* Success is indicated by returning -EINPROGRESS,
* at which time the URB will normally have been unlinked but not yet
* given back to the device driver. When it is called, the completion
* function will see urb->status == -ECONNRESET. Failure is indicated
* by any other return value. Unlinking will fail when the URB is not
* currently "linked" (i.e., it was never submitted, or it was unlinked
* before, or the hardware is already finished with it), even if the
* completion handler has not yet run.
* Unlinking and Endpoint Queues:
* Host Controller Drivers (HCDs) place all the URBs for a particular
* endpoint in a queue. Normally the queue advances as the controller
* hardware processes each request. But when an URB terminates with an
* error its queue stops, at least until that URB's completion routine
* returns. It is guaranteed that the queue will not restart until all
* its unlinked URBs have been fully retired, with their completion
* routines run, even if that's not until some time after the original
* completion handler returns. Normally the same behavior and guarantees
* apply when an URB terminates because it was unlinked; however if an
* URB is unlinked before the hardware has started to execute it, then
* its queue is not guaranteed to stop until all the preceding URBs have
* completed.
* This means that USB device drivers can safely build deep queues for
* large or complex transfers, and clean them up reliably after any sort
* of aborted transfer by unlinking all pending URBs at the first fault.
* Note that an URB terminating early because a short packet was received
* will count as an error if and only if the URB_SHORT_NOT_OK flag is set.
* Also, that all unlinks performed in any URB completion handler must
* be asynchronous.
* Queues for isochronous endpoints are treated differently, because they
* advance at fixed rates. Such queues do not stop when an URB is unlinked.
* An unlinked URB may leave a gap in the stream of packets. It is undefined
* whether such gaps can be filled in.
* When a control URB terminates with an error, it is likely that the
* status stage of the transfer will not take place, even if it is merely
* a soft error resulting from a short-packet with URB_SHORT_NOT_OK set.
int usb_unlink_urb(struct urb *urb)
if (!urb)
return -EINVAL;
if (!(urb->dev && urb->dev->bus && urb->dev->bus->op))
return -ENODEV;
return urb->dev->bus->op->unlink_urb(urb, -ECONNRESET);
* usb_kill_urb - cancel a transfer request and wait for it to finish
* @urb: pointer to URB describing a previously submitted request,
* may be NULL
* This routine cancels an in-progress request. It is guaranteed that
* upon return all completion handlers will have finished and the URB
* will be totally idle and available for reuse. These features make
* this an ideal way to stop I/O in a disconnect() callback or close()
* function. If the request has not already finished or been unlinked
* the completion handler will see urb->status == -ENOENT.
* While the routine is running, attempts to resubmit the URB will fail
* with error -EPERM. Thus even if the URB's completion handler always
* tries to resubmit, it will not succeed and the URB will become idle.
* This routine may not be used in an interrupt context (such as a bottom
* half or a completion handler), or when holding a spinlock, or in other
* situations where the caller can't schedule().
void usb_kill_urb(struct urb *urb)
if (!(urb && urb->dev && urb->dev->bus && urb->dev->bus->op))
urb->dev->bus->op->unlink_urb(urb, -ENOENT);
wait_event(usb_kill_urb_queue, atomic_read(&urb->use_count) == 0);