hcd.c

h内核

	struct list_head		*tmp;
	int				retval;

	if (!urb)
		return -EINVAL;
	if (!urb->dev || !urb->dev->bus)
		return -ENODEV;
	ep = (usb_pipein(urb->pipe) ? urb->dev->ep_in : urb->dev->ep_out)
			[usb_pipeendpoint(urb->pipe)];
	if (!ep)
		return -ENODEV;

	/*
	 * we contend for urb->status with the hcd core,
	 * which changes it while returning the urb.
	 *
	 * Caller guaranteed that the urb pointer hasn't been freed, and
	 * that it was submitted.  But as a rule it can't know whether or
	 * not it's already been unlinked ... so we respect the reversed
	 * lock sequence needed for the usb_hcd_giveback_urb() code paths
	 * (urb lock, then hcd_data_lock) in case some other CPU is now
	 * unlinking it.
	 */
	spin_lock_irqsave (&urb->lock, flags);
	spin_lock (&hcd_data_lock);

	sys = &urb->dev->dev;
	hcd = urb->dev->bus->hcpriv;
	if (hcd == NULL) {
		retval = -ENODEV;
		goto done;
	}

	/* running ~= hc unlink handshake works (irq, timer, etc)
	 * halted ~= no unlink handshake is needed
	 * suspended, resuming == should never happen
	 */
	WARN_ON (!HCD_IS_RUNNING (hcd->state) && hcd->state != USB_STATE_HALT);

	/* insist the urb is still queued */
	list_for_each(tmp, &ep->urb_list) {
		if (tmp == &urb->urb_list)
			break;
	}
	if (tmp != &urb->urb_list) {
		retval = -EIDRM;
		goto done;
	}

	/* Any status except -EINPROGRESS means something already started to
	 * unlink this URB from the hardware.  So there's no more work to do.
	 */
	if (urb->status != -EINPROGRESS) {
		retval = -EBUSY;
		goto done;
	}

	/* IRQ setup can easily be broken so that USB controllers
	 * never get completion IRQs ... maybe even the ones we need to
	 * finish unlinking the initial failed usb_set_address()
	 * or device descriptor fetch.
	 */
	if (!hcd->saw_irq && hcd->self.root_hub != urb->dev) {
		dev_warn (hcd->self.controller, "Unlink after no-IRQ?  "
			"Controller is probably using the wrong IRQ."
			"\n");
		hcd->saw_irq = 1;
	}

	urb->status = status;

	spin_unlock (&hcd_data_lock);
	spin_unlock_irqrestore (&urb->lock, flags);

	retval = unlink1 (hcd, urb);
	if (retval == 0)
		retval = -EINPROGRESS;
	return retval;

done:
	spin_unlock (&hcd_data_lock);
	spin_unlock_irqrestore (&urb->lock, flags);
	if (retval != -EIDRM && sys && sys->driver)
		dev_dbg (sys, "hcd_unlink_urb %p fail %d\n", urb, retval);
	return retval;
}

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

/* disables the endpoint: cancels any pending urbs, then synchronizes with
 * the hcd to make sure all endpoint state is gone from hardware. use for
 * set_configuration, set_interface, driver removal, physical disconnect.
 *
 * example:  a qh stored in ep->hcpriv, holding state related to endpoint
 * type, maxpacket size, toggle, halt status, and scheduling.
 */
static void
hcd_endpoint_disable (struct usb_device *udev, struct usb_host_endpoint *ep)
{
	struct usb_hcd		*hcd;
	struct urb		*urb;

	hcd = udev->bus->hcpriv;

	WARN_ON (!HCD_IS_RUNNING (hcd->state) && hcd->state != USB_STATE_HALT);

	local_irq_disable ();

	/* FIXME move most of this into message.c as part of its
	 * endpoint disable logic
	 */

	/* ep is already gone from udev->ep_{in,out}[]; no more submits */
rescan:
	spin_lock (&hcd_data_lock);
	list_for_each_entry (urb, &ep->urb_list, urb_list) {
		int	tmp;

		/* another cpu may be in hcd, spinning on hcd_data_lock
		 * to giveback() this urb.  the races here should be
		 * small, but a full fix needs a new "can't submit"
		 * urb state.
		 * FIXME urb->reject should allow that...
		 */
		if (urb->status != -EINPROGRESS)
			continue;
		usb_get_urb (urb);
		spin_unlock (&hcd_data_lock);

		spin_lock (&urb->lock);
		tmp = urb->status;
		if (tmp == -EINPROGRESS)
			urb->status = -ESHUTDOWN;
		spin_unlock (&urb->lock);

		/* kick hcd unless it's already returning this */
		if (tmp == -EINPROGRESS) {
			tmp = urb->pipe;
			unlink1 (hcd, urb);
			dev_dbg (hcd->self.controller,
				"shutdown urb %p pipe %08x ep%d%s%s\n",
				urb, tmp, usb_pipeendpoint (tmp),
				(tmp & USB_DIR_IN) ? "in" : "out",
				({ char *s; \
				 switch (usb_pipetype (tmp)) { \
				 case PIPE_CONTROL:	s = ""; break; \
				 case PIPE_BULK:	s = "-bulk"; break; \
				 case PIPE_INTERRUPT:	s = "-intr"; break; \
				 default: 		s = "-iso"; break; \
				}; s;}));
		}
		usb_put_urb (urb);

		/* list contents may have changed */
		goto rescan;
	}
	spin_unlock (&hcd_data_lock);
	local_irq_enable ();

	/* synchronize with the hardware, so old configuration state
	 * clears out immediately (and will be freed).
	 */
	might_sleep ();
	if (hcd->driver->endpoint_disable)
		hcd->driver->endpoint_disable (hcd, ep);
}

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

#ifdef	CONFIG_USB_SUSPEND

static int hcd_hub_suspend (struct usb_bus *bus)
{
	struct usb_hcd		*hcd;

	hcd = container_of (bus, struct usb_hcd, self);
	if (hcd->driver->hub_suspend)
		return hcd->driver->hub_suspend (hcd);
	return 0;
}

static int hcd_hub_resume (struct usb_bus *bus)
{
	struct usb_hcd		*hcd;

	hcd = container_of (bus, struct usb_hcd, self);
	if (hcd->driver->hub_resume)
		return hcd->driver->hub_resume (hcd);
	return 0;
}

#endif

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

#ifdef	CONFIG_USB_OTG

/**
 * usb_bus_start_enum - start immediate enumeration (for OTG)
 * @bus: the bus (must use hcd framework)
 * @port: 1-based number of port; usually bus->otg_port
 * Context: in_interrupt()
 *
 * Starts enumeration, with an immediate reset followed later by
 * khubd identifying and possibly configuring the device.
 * This is needed by OTG controller drivers, where it helps meet
 * HNP protocol timing requirements for starting a port reset.
 */
int usb_bus_start_enum(struct usb_bus *bus, unsigned port_num)
{
	struct usb_hcd		*hcd;
	int			status = -EOPNOTSUPP;

	/* NOTE: since HNP can't start by grabbing the bus's address0_sem,
	 * boards with root hubs hooked up to internal devices (instead of
	 * just the OTG port) may need more attention to resetting...
	 */
	hcd = container_of (bus, struct usb_hcd, self);
	if (port_num && hcd->driver->start_port_reset)
		status = hcd->driver->start_port_reset(hcd, port_num);

	/* run khubd shortly after (first) root port reset finishes;
	 * it may issue others, until at least 50 msecs have passed.
	 */
	if (status == 0)
		mod_timer(&hcd->rh_timer, jiffies + msecs_to_jiffies(10));
	return status;
}
EXPORT_SYMBOL (usb_bus_start_enum);

#endif

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

/*
 * usb_hcd_operations - adapts usb_bus framework to HCD framework (bus glue)
 */
static struct usb_operations usb_hcd_operations = {
	.get_frame_number =	hcd_get_frame_number,
	.submit_urb =		hcd_submit_urb,
	.unlink_urb =		hcd_unlink_urb,
	.buffer_alloc =		hcd_buffer_alloc,
	.buffer_free =		hcd_buffer_free,
	.disable =		hcd_endpoint_disable,
#ifdef	CONFIG_USB_SUSPEND
	.hub_suspend =		hcd_hub_suspend,
	.hub_resume =		hcd_hub_resume,
#endif
};

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

/**
 * usb_hcd_giveback_urb - return URB from HCD to device driver
 * @hcd: host controller returning the URB
 * @urb: urb being returned to the USB device driver.
 * @regs: pt_regs, passed down to the URB completion handler
 * Context: in_interrupt()
 *
 * This hands the URB from HCD to its USB device driver, using its
 * completion function.  The HCD has freed all per-urb resources
 * (and is done using urb->hcpriv).  It also released all HCD locks;
 * the device driver won't cause problems if it frees, modifies,
 * or resubmits this URB.
 */
void usb_hcd_giveback_urb (struct usb_hcd *hcd, struct urb *urb, struct pt_regs *regs)
{
	urb_unlink (urb);

	// NOTE:  a generic device/urb monitoring hook would go here.
	// hcd_monitor_hook(MONITOR_URB_FINISH, urb, dev)
	// It would catch exit/unlink paths for all urbs.

	/* lower level hcd code should use *_dma exclusively */
	if (hcd->self.controller->dma_mask) {
		if (usb_pipecontrol (urb->pipe)
			&& !(urb->transfer_flags & URB_NO_SETUP_DMA_MAP))
			dma_unmap_single (hcd->self.controller, urb->setup_dma,
					sizeof (struct usb_ctrlrequest),
					DMA_TO_DEVICE);
		if (urb->transfer_buffer_length != 0
			&& !(urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP))
			dma_unmap_single (hcd->self.controller, 
					urb->transfer_dma,
					urb->transfer_buffer_length,
					usb_pipein (urb->pipe)
					    ? DMA_FROM_DEVICE
					    : DMA_TO_DEVICE);
	}

	/* pass ownership to the completion handler */
	urb->complete (urb, regs);
	atomic_dec (&urb->use_count);
	if (unlikely (urb->reject))
		wake_up (&usb_kill_urb_queue);
	usb_put_urb (urb);
}
EXPORT_SYMBOL (usb_hcd_giveback_urb);

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

/**
 * usb_hcd_irq - hook IRQs to HCD framework (bus glue)
 * @irq: the IRQ being raised
 * @__hcd: pointer to the HCD whose IRQ is beinng signaled
 * @r: saved hardware registers
 *
 * When registering a USB bus through the HCD framework code, use this
 * to handle interrupts.  The PCI glue layer does so automatically; only
 * bus glue for non-PCI system busses will need to use this.
 */
irqreturn_t usb_hcd_irq (int irq, void *__hcd, struct pt_regs * r)
{
	struct usb_hcd		*hcd = __hcd;
	int			start = hcd->state;

	if (start == USB_STATE_HALT)
		return IRQ_NONE;
	if (hcd->driver->irq (hcd, r) == IRQ_NONE)
		return IRQ_NONE;

	hcd->saw_irq = 1;
	if (hcd->state != start && hcd->state == USB_STATE_HALT)
		usb_hc_died (hcd);
	return IRQ_HANDLED;
}
EXPORT_SYMBOL (usb_hcd_irq);

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

/**
 * usb_hc_died - report abnormal shutdown of a host controller (bus glue)
 * @hcd: pointer to the HCD representing the controller
 *
 * This is called by bus glue to report a USB host controller that died
 * while operations may still have been pending.  It's called automatically
 * by the PCI glue, so only glue for non-PCI busses should need to call it. 
 */
void usb_hc_died (struct usb_hcd *hcd)
{
	dev_err (hcd->self.controller, "HC died; cleaning up\n");

	/* make khubd clean up old urbs and devices */
	usb_set_device_state(hcd->self.root_hub, USB_STATE_NOTATTACHED);
	mod_timer(&hcd->rh_timer, jiffies);
}

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

static void hcd_release (struct usb_bus *bus)
{
	struct usb_hcd *hcd;

	hcd = container_of(bus, struct usb_hcd, self);
	kfree(hcd);
}

/**
 * usb_create_hcd - create and initialize an HCD structure
 * @driver: HC driver that will use this hcd
 * Context: !in_interrupt()
 *
 * Allocate a struct usb_hcd, with extra space at the end for the
 * HC driver's private data.  Initialize the generic members of the
 * hcd structure.
 *
 * If memory is unavailable, returns NULL.
 */
struct usb_hcd *usb_create_hcd (const struct hc_driver *driver)
{
	struct usb_hcd *hcd;

	hcd = kcalloc(1, sizeof(*hcd) + driver->hcd_priv_size, GFP_KERNEL);
	if (!hcd)
		return NULL;

	usb_bus_init(&hcd->self);
	hcd->self.op = &usb_hcd_operations;
	hcd->self.hcpriv = hcd;
	hcd->self.release = &hcd_release;

	init_timer(&hcd->rh_timer);

	hcd->driver = driver;
	hcd->product_desc = (driver->product_desc) ? driver->product_desc :
			"USB Host Controller";
	hcd->state = USB_STATE_HALT;

	return hcd;
}
EXPORT_SYMBOL (usb_create_hcd);

void usb_put_hcd (struct usb_hcd *hcd)
{
	usb_bus_put(&hcd->self);
}
EXPORT_SYMBOL (usb_put_hcd);