diff options
Diffstat (limited to 'drivers/usb/core/urb.c')
| -rw-r--r-- | drivers/usb/core/urb.c | 511 |
1 files changed, 511 insertions, 0 deletions
diff --git a/drivers/usb/core/urb.c b/drivers/usb/core/urb.c new file mode 100644 index 000000000000..dc838f81742c --- /dev/null +++ b/drivers/usb/core/urb.c @@ -0,0 +1,511 @@ +#include <linux/config.h> +#include <linux/module.h> +#include <linux/string.h> +#include <linux/bitops.h> +#include <linux/slab.h> +#include <linux/init.h> + +#ifdef CONFIG_USB_DEBUG + #define DEBUG +#else + #undef DEBUG +#endif +#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); + 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); + spin_lock_init(&urb->lock); + } +} + +/** + * 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, int mem_flags) +{ + struct urb *urb; + + urb = (struct urb *)kmalloc(sizeof(struct urb) + + iso_packets * sizeof(struct usb_iso_packet_descriptor), + mem_flags); + if (!urb) { + err("alloc_urb: kmalloc failed"); + return NULL; + } + usb_init_urb(urb); + 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) + kref_get(&urb->kref); + 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 cancelation"). + * + * 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 cancelation). + * + * 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_ATOMIC. + * + * 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, int 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->state == USB_STATE_SUSPENDED) + return -EHOSTUNREACH; + 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) { + dev_dbg(&dev->dev, + "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 */ + allowed = URB_ASYNC_UNLINK; // affects later unlinks + allowed |= (URB_NO_TRANSFER_DMA_MAP | URB_NO_SETUP_DMA_MAP); + allowed |= URB_NO_INTERRUPT; + switch (temp) { + case PIPE_BULK: + if (is_out) + allowed |= URB_ZERO_PACKET; + /* FALLTHROUGH */ + case PIPE_CONTROL: + allowed |= URB_NO_FSBR; /* only affects UHCI */ + /* FALLTHROUGH */ + default: /* all non-iso endpoints */ + if (!is_out) + allowed |= URB_SHORT_NOT_OK; + break; + case PIPE_ISOCHRONOUS: + allowed |= URB_ISO_ASAP; + break; + } + 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; + } + } +#endif + /* + * 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) { + case PIPE_ISOCHRONOUS: + case PIPE_INTERRUPT: + /* 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; + break; + case USB_SPEED_FULL: /* units are frames/msec */ + case USB_SPEED_LOW: + 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; + } + break; + default: + 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 cancelation 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. + * + * In the past, clearing the URB_ASYNC_UNLINK transfer flag for the + * URB indicated that the request was synchronous. This usage is now + * deprecated; if the flag is clear the call will be forwarded to + * usb_kill_urb() and the return value will be 0. In the future, drivers + * should call usb_kill_urb() directly for synchronous unlinking. + * + * When the URB_ASYNC_UNLINK transfer flag for the URB is set, this + * request is 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 any + * fault (such as an error, or being unlinked) 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. + * + * 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->transfer_flags & URB_ASYNC_UNLINK)) { +#ifdef CONFIG_DEBUG_KERNEL + if (printk_ratelimit()) { + printk(KERN_NOTICE "usb_unlink_urb() is deprecated for " + "synchronous unlinks. Use usb_kill_urb() instead.\n"); + WARN_ON(1); + } +#endif + usb_kill_urb(urb); + return 0; + } + 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)) + return; + spin_lock_irq(&urb->lock); + ++urb->reject; + spin_unlock_irq(&urb->lock); + + urb->dev->bus->op->unlink_urb(urb, -ENOENT); + wait_event(usb_kill_urb_queue, atomic_read(&urb->use_count) == 0); + + spin_lock_irq(&urb->lock); + --urb->reject; + spin_unlock_irq(&urb->lock); +} + +EXPORT_SYMBOL(usb_init_urb); +EXPORT_SYMBOL(usb_alloc_urb); +EXPORT_SYMBOL(usb_free_urb); +EXPORT_SYMBOL(usb_get_urb); +EXPORT_SYMBOL(usb_submit_urb); +EXPORT_SYMBOL(usb_unlink_urb); +EXPORT_SYMBOL(usb_kill_urb); + |