hcd.c

linux core 函数例程

	/* any errors get returned through the urb completion */
	usb_hcd_giveback_urb (hcd, urb);
	return 0;
}

/*-------------------------------------------------------------------------*/

/*
 * Root Hub interrupt transfers are synthesized with a timer.
 * Completions are called in_interrupt() but not in_irq().
 */

static void rh_report_status (unsigned long ptr);

static int rh_status_urb (struct usb_hcd *hcd, struct urb *urb) 
{
	int	len = 1 + (urb->dev->maxchild / 8);

	/* rh_timer protected by hcd_data_lock */
	if (timer_pending (&hcd->rh_timer)
			|| urb->status != -EINPROGRESS
			|| !HCD_IS_RUNNING (hcd->state)
			|| urb->transfer_buffer_length < len) {
		dbg ("not queuing status urb, stat %d", urb->status);
		return -EINVAL;
	}

	urb->hcpriv = hcd;	/* nonzero to indicate it's queued */
	init_timer (&hcd->rh_timer);
	hcd->rh_timer.function = rh_report_status;
	hcd->rh_timer.data = (unsigned long) urb;
	/* USB 2.0 spec says 256msec; this is close enough */
	hcd->rh_timer.expires = jiffies + HZ/4;
	add_timer (&hcd->rh_timer);
	return 0;
}

/* timer callback */

static void rh_report_status (unsigned long ptr)
{
	struct urb	*urb;
	struct usb_hcd	*hcd;
	int		length;
	unsigned long	flags;

	urb = (struct urb *) ptr;
	spin_lock_irqsave (&urb->lock, flags);
	if (!urb->dev) {
		spin_unlock_irqrestore (&urb->lock, flags);
		return;
	}

	hcd = urb->dev->bus->hcpriv;
	if (urb->status == -EINPROGRESS) {
		if (HCD_IS_RUNNING (hcd->state)) {
			length = hcd->driver->hub_status_data (hcd,
					urb->transfer_buffer);
			spin_unlock_irqrestore (&urb->lock, flags);
			if (length > 0) {
				urb->actual_length = length;
				urb->status = 0;
				urb->complete (urb);
			}
			spin_lock_irqsave (&hcd_data_lock, flags);
			urb->status = -EINPROGRESS;
			if (HCD_IS_RUNNING (hcd->state)
					&& rh_status_urb (hcd, urb) != 0) {
				/* another driver snuck in? */
				dbg ("%s, can't resubmit roothub status urb?",
					hcd->self.bus_name);
				spin_unlock_irqrestore (&hcd_data_lock, flags);
				BUG ();
			}
			spin_unlock_irqrestore (&hcd_data_lock, flags);
		} else
			spin_unlock_irqrestore (&urb->lock, flags);
	} else {
		/* this urb's been unlinked */
		urb->hcpriv = 0;
		spin_unlock_irqrestore (&urb->lock, flags);

		usb_hcd_giveback_urb (hcd, urb);
	}
}

/*-------------------------------------------------------------------------*/

static int rh_urb_enqueue (struct usb_hcd *hcd, struct urb *urb)
{
	if (usb_pipeint (urb->pipe)) {
		int		retval;
		unsigned long	flags;

		spin_lock_irqsave (&hcd_data_lock, flags);
		retval = rh_status_urb (hcd, urb);
		spin_unlock_irqrestore (&hcd_data_lock, flags);
		return retval;
	}
	if (usb_pipecontrol (urb->pipe))
		return rh_call_control (hcd, urb);
	else
		return -EINVAL;
}

/*-------------------------------------------------------------------------*/

static void rh_status_dequeue (struct usb_hcd *hcd, struct urb *urb)
{
	unsigned long	flags;

	spin_lock_irqsave (&hcd_data_lock, flags);
	del_timer_sync (&hcd->rh_timer);
	hcd->rh_timer.data = 0;
	spin_unlock_irqrestore (&hcd_data_lock, flags);

	/* we rely on RH callback code not unlinking its URB! */
	usb_hcd_giveback_urb (hcd, urb);
}

/*-------------------------------------------------------------------------*/

/* exported only within usbcore */
void usb_bus_get (struct usb_bus *bus)
{
	atomic_inc (&bus->refcnt);
}

/* exported only within usbcore */
void usb_bus_put (struct usb_bus *bus)
{
	if (atomic_dec_and_test (&bus->refcnt))
		kfree (bus);
}

/*-------------------------------------------------------------------------*/

/* shared initialization code */
static void usb_init_bus (struct usb_bus *bus)
{
	memset (&bus->devmap, 0, sizeof(struct usb_devmap));

#ifdef DEVNUM_ROUND_ROBIN
	bus->devnum_next = 1;
#endif /* DEVNUM_ROUND_ROBIN */

	bus->root_hub = NULL;
	bus->hcpriv = NULL;
	bus->busnum = -1;
	bus->bandwidth_allocated = 0;
	bus->bandwidth_int_reqs  = 0;
	bus->bandwidth_isoc_reqs = 0;

	INIT_LIST_HEAD (&bus->bus_list);

	atomic_set (&bus->refcnt, 1);
}

/**
 * usb_alloc_bus - creates a new USB host controller structure
 * @op: pointer to a struct usb_operations that this bus structure should use
 * Context: !in_interrupt()
 *
 * Creates a USB host controller bus structure with the specified 
 * usb_operations and initializes all the necessary internal objects.
 *
 * If no memory is available, NULL is returned.
 *
 * The caller should call usb_free_bus() when it is finished with the structure.
 */
struct usb_bus *usb_alloc_bus (struct usb_operations *op)
{
	struct usb_bus *bus;

	bus = kmalloc (sizeof *bus, GFP_KERNEL);
	if (!bus)
		return NULL;
	usb_init_bus (bus);
	bus->op = op;
	return bus;
}
EXPORT_SYMBOL (usb_alloc_bus);

/**
 * usb_free_bus - frees the memory used by a bus structure
 * @bus: pointer to the bus to free
 *
 * To be invoked by a HCD, only as the last step of decoupling from
 * hardware.  It is an error to call this if the reference count is
 * anything but one.  That would indicate that some system component
 * did not correctly shut down, and thought the hardware was still
 * accessible.
 */
void usb_free_bus (struct usb_bus *bus)
{
	if (!bus)
		return;
	if (atomic_read (&bus->refcnt) != 1)
		err ("usb_free_bus #%d, count != 1", bus->busnum);
	usb_bus_put (bus);
}
EXPORT_SYMBOL (usb_free_bus);

/*-------------------------------------------------------------------------*/

/**
 * usb_register_bus - registers the USB host controller with the usb core
 * @bus: pointer to the bus to register
 * Context: !in_interrupt()
 *
 * Assigns a bus number, and links the controller into usbcore data
 * structures so that it can be seen by scanning the bus list.
 */
void usb_register_bus(struct usb_bus *bus)
{
	int busnum;

	down (&usb_bus_list_lock);
	busnum = find_next_zero_bit (busmap.busmap, USB_MAXBUS, 1);
	if (busnum < USB_MAXBUS) {
		set_bit (busnum, busmap.busmap);
		bus->busnum = busnum;
	} else
		warn ("too many buses");

	usb_bus_get (bus);

	/* Add it to the list of buses */
	list_add (&bus->bus_list, &usb_bus_list);
	up (&usb_bus_list_lock);

	usbfs_add_bus (bus);

	info ("new USB bus registered, assigned bus number %d", bus->busnum);
}
EXPORT_SYMBOL (usb_register_bus);

/**
 * usb_deregister_bus - deregisters the USB host controller
 * @bus: pointer to the bus to deregister
 * Context: !in_interrupt()
 *
 * Recycles the bus number, and unlinks the controller from usbcore data
 * structures so that it won't be seen by scanning the bus list.
 */
void usb_deregister_bus (struct usb_bus *bus)
{
	info ("USB bus %d deregistered", bus->busnum);

	/*
	 * NOTE: make sure that all the devices are removed by the
	 * controller code, as well as having it call this when cleaning
	 * itself up
	 */
	down (&usb_bus_list_lock);
	list_del (&bus->bus_list);
	up (&usb_bus_list_lock);

	usbfs_remove_bus (bus);

	clear_bit (bus->busnum, busmap.busmap);

	usb_bus_put (bus);
}
EXPORT_SYMBOL (usb_deregister_bus);

/**
 * usb_register_root_hub - called by HCD to register its root hub 
 * @usb_dev: the usb root hub device to be registered.
 * @parent_dev: the parent device of this root hub.
 *
 * The USB host controller calls this function to register the root hub
 * properly with the USB subsystem.  It sets up the device properly in
 * the driverfs tree, and then calls usb_new_device() to register the
 * usb device.
 */
int usb_register_root_hub (struct usb_device *usb_dev, struct device *parent_dev)
{
	int retval;

	usb_dev->dev.parent = parent_dev;
	strcpy (&usb_dev->dev.name[0], "usb_name");
	strcpy (&usb_dev->dev.bus_id[0], "usb_bus");
	retval = usb_new_device (usb_dev);
	if (retval)
		put_device (&usb_dev->dev);
	return retval;
}
EXPORT_SYMBOL (usb_register_root_hub);


/*-------------------------------------------------------------------------*/

/**
 * usb_calc_bus_time: approximate periodic transaction time in nanoseconds
 * @speed: from dev->speed; USB_SPEED_{LOW,FULL,HIGH}
 * @is_input: true iff the transaction sends data to the host
 * @is_isoc: true for isochronous transactions, false for interrupt ones
 * @bytecount: how many bytes in the transaction.
 *
 * Returns approximate bus time in nanoseconds for a periodic transaction.
 * See USB 2.0 spec section 5.11.3; only periodic transfers need to be
 * scheduled in software, this function is only used for such scheduling.
 */
long usb_calc_bus_time (int speed, int is_input, int isoc, int bytecount)
{
	unsigned long	tmp;

	switch (speed) {
	case USB_SPEED_LOW: 	/* INTR only */
		if (is_input) {
			tmp = (67667L * (31L + 10L * BitTime (bytecount))) / 1000L;
			return (64060L + (2 * BW_HUB_LS_SETUP) + BW_HOST_DELAY + tmp);
		} else {
			tmp = (66700L * (31L + 10L * BitTime (bytecount))) / 1000L;
			return (64107L + (2 * BW_HUB_LS_SETUP) + BW_HOST_DELAY + tmp);
		}
	case USB_SPEED_FULL:	/* ISOC or INTR */
		if (isoc) {
			tmp = (8354L * (31L + 10L * BitTime (bytecount))) / 1000L;
			return (((is_input) ? 7268L : 6265L) + BW_HOST_DELAY + tmp);
		} else {
			tmp = (8354L * (31L + 10L * BitTime (bytecount))) / 1000L;
			return (9107L + BW_HOST_DELAY + tmp);
		}
	case USB_SPEED_HIGH:	/* ISOC or INTR */
		// FIXME adjust for input vs output
		if (isoc)
			tmp = HS_USECS (bytecount);
		else
			tmp = HS_USECS_ISO (bytecount);
		return tmp;
	default:
		dbg ("bogus device speed!");
		return -1;
	}
}
EXPORT_SYMBOL (usb_calc_bus_time);

/*
 * usb_check_bandwidth():
 *
 * old_alloc is from host_controller->bandwidth_allocated in microseconds;
 * bustime is from calc_bus_time(), but converted to microseconds.
 *
 * returns <bustime in us> if successful,
 * or -ENOSPC if bandwidth request fails.
 *
 * FIXME:
 * This initial implementation does not use Endpoint.bInterval
 * in managing bandwidth allocation.
 * It probably needs to be expanded to use Endpoint.bInterval.
 * This can be done as a later enhancement (correction).
 *
 * This will also probably require some kind of
 * frame allocation tracking...meaning, for example,
 * that if multiple drivers request interrupts every 10 USB frames,
 * they don't all have to be allocated at
 * frame numbers N, N+10, N+20, etc.  Some of them could be at
 * N+11, N+21, N+31, etc., and others at
 * N+12, N+22, N+32, etc.
 *
 * Similarly for isochronous transfers...
 *
 * Individual HCDs can schedule more directly ... this logic
 * is not correct for high speed transfers.
 */
int usb_check_bandwidth (struct usb_device *dev, struct urb *urb)
{
	unsigned int	pipe = urb->pipe;
	long		bustime;
	int		is_in = usb_pipein (pipe);
	int		is_iso = usb_pipeisoc (pipe);
	int		old_alloc = dev->bus->bandwidth_allocated;
	int		new_alloc;


	bustime = NS_TO_US (usb_calc_bus_time (dev->speed, is_in, is_iso,
			usb_maxpacket (dev, pipe, !is_in)));
	if (is_iso)
		bustime /= urb->number_of_packets;

	new_alloc = old_alloc + (int) bustime;
	if (new_alloc > FRAME_TIME_MAX_USECS_ALLOC) {
#ifdef	DEBUG
		char	*mode = 
#ifdef CONFIG_USB_BANDWIDTH
			"";
#else
			"would have ";
#endif
		dbg ("usb_check_bandwidth %sFAILED: %d + %ld = %d usec",
			mode, old_alloc, bustime, new_alloc);
#endif
#ifdef CONFIG_USB_BANDWIDTH
		bustime = -ENOSPC;	/* report error */
#endif
	}

	return bustime;
}
EXPORT_SYMBOL (usb_check_bandwidth);


/**
 * usb_claim_bandwidth - records bandwidth for a periodic transfer
 * @dev: source/target of request
 * @urb: request (urb->dev == dev)
 * @bustime: bandwidth consumed, in (average) microseconds per frame
 * @isoc: true iff the request is isochronous
 *
 * Bus bandwidth reservations are recorded purely for diagnostic purposes.
 * HCDs are expected not to overcommit periodic bandwidth, and to record such
 * reservations whenever endpoints are added to the periodic schedule.
 *
 * FIXME averaging per-frame is suboptimal.  Better to sum over the HCD's
 * entire periodic schedule ... 32 frames for OHCI, 1024 for UHCI, settable
 * for EHCI (256/512/1024 frames, default 1024) and have the bus expose how
 * large its periodic schedule is.
 */
void usb_claim_bandwidth (struct usb_device *dev, struct urb *urb, int bustime, int isoc)
{
	dev->bus->bandwidth_allocated += bustime;
	if (isoc)
		dev->bus->bandwidth_isoc_reqs++;
	else
		dev->bus->bandwidth_int_reqs++;
	urb->bandwidth = bustime;

#ifdef USB_BANDWIDTH_MESSAGES
	dbg ("bandwidth alloc increased by %d (%s) to %d for %d requesters",
		bustime,
		isoc ? "ISOC" : "INTR",
		dev->bus->bandwidth_allocated,
		dev->bus->bandwidth_int_reqs + dev->bus->bandwidth_isoc_reqs);
#endif
}
EXPORT_SYMBOL (usb_claim_bandwidth);


/**
 * usb_release_bandwidth - reverses effect of usb_claim_bandwidth()
 * @dev: source/target of request
 * @urb: request (urb->dev == dev)
 * @isoc: true iff the request is isochronous
 *
 * This records that previously allocated bandwidth has been released.
 * Bandwidth is released when endpoints are removed from the host controller's
 * periodic schedule.
 */
void usb_release_bandwidth (struct usb_device *dev, struct urb *urb, int isoc)
{
	dev->bus->bandwidth_allocated -= urb->bandwidth;
	if (isoc)