message.c

h内核

/*
 * message.c - synchronous message handling
 */

#include <linux/config.h>

#ifdef CONFIG_USB_DEBUG
	#define DEBUG
#else
	#undef DEBUG
#endif

#include <linux/pci.h>	/* for scatterlist macros */
#include <linux/usb.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/timer.h>
#include <linux/ctype.h>
#include <linux/device.h>
#include <asm/byteorder.h>

#include "hcd.h"	/* for usbcore internals */
#include "usb.h"

static void usb_api_blocking_completion(struct urb *urb, struct pt_regs *regs)
{
	complete((struct completion *)urb->context);
}


static void timeout_kill(unsigned long data)
{
	struct urb	*urb = (struct urb *) data;

	usb_unlink_urb(urb);
}

// Starts urb and waits for completion or timeout
// note that this call is NOT interruptible, while
// many device driver i/o requests should be interruptible
static int usb_start_wait_urb(struct urb *urb, int timeout, int* actual_length)
{ 
	struct completion	done;
	struct timer_list	timer;
	int			status;

	init_completion(&done); 	
	urb->context = &done;
	urb->transfer_flags |= URB_ASYNC_UNLINK;
	urb->actual_length = 0;
	status = usb_submit_urb(urb, GFP_NOIO);

	if (status == 0) {
		if (timeout > 0) {
			init_timer(&timer);
			timer.expires = jiffies + timeout;
			timer.data = (unsigned long)urb;
			timer.function = timeout_kill;
			/* grr.  timeout _should_ include submit delays. */
			add_timer(&timer);
		}
		wait_for_completion(&done);
		status = urb->status;
		/* note:  HCDs return ETIMEDOUT for other reasons too */
		if (status == -ECONNRESET) {
			dev_warn(&urb->dev->dev,
				"%s timed out on ep%d%s\n",
				current->comm,
				usb_pipeendpoint(urb->pipe),
				usb_pipein(urb->pipe) ? "in" : "out");
			status = -ETIMEDOUT;
		}
		if (timeout > 0)
			del_timer_sync(&timer);
	}

	if (actual_length)
		*actual_length = urb->actual_length;
	usb_free_urb(urb);
	return status;
}

/*-------------------------------------------------------------------*/
// returns status (negative) or length (positive)
int usb_internal_control_msg(struct usb_device *usb_dev, unsigned int pipe, 
			    struct usb_ctrlrequest *cmd,  void *data, int len, int timeout)
{
	struct urb *urb;
	int retv;
	int length;

	urb = usb_alloc_urb(0, GFP_NOIO);
	if (!urb)
		return -ENOMEM;
  
	usb_fill_control_urb(urb, usb_dev, pipe, (unsigned char *)cmd, data,
			     len, usb_api_blocking_completion, NULL);

	retv = usb_start_wait_urb(urb, timeout, &length);
	if (retv < 0)
		return retv;
	else
		return length;
}

/**
 *	usb_control_msg - Builds a control urb, sends it off and waits for completion
 *	@dev: pointer to the usb device to send the message to
 *	@pipe: endpoint "pipe" to send the message to
 *	@request: USB message request value
 *	@requesttype: USB message request type value
 *	@value: USB message value
 *	@index: USB message index value
 *	@data: pointer to the data to send
 *	@size: length in bytes of the data to send
 *	@timeout: time in jiffies to wait for the message to complete before
 *		timing out (if 0 the wait is forever)
 *	Context: !in_interrupt ()
 *
 *	This function sends a simple control message to a specified endpoint
 *	and waits for the message to complete, or timeout.
 *	
 *	If successful, it returns the number of bytes transferred, otherwise a negative error number.
 *
 *	Don't use this function from within an interrupt context, like a
 *	bottom half handler.  If you need an asynchronous message, or need to send
 *	a message from within interrupt context, use usb_submit_urb()
 *      If a thread in your driver uses this call, make sure your disconnect()
 *      method can wait for it to complete.  Since you don't have a handle on
 *      the URB used, you can't cancel the request.
 */
int usb_control_msg(struct usb_device *dev, unsigned int pipe, __u8 request, __u8 requesttype,
			 __u16 value, __u16 index, void *data, __u16 size, int timeout)
{
	struct usb_ctrlrequest *dr = kmalloc(sizeof(struct usb_ctrlrequest), GFP_NOIO);
	int ret;
	
	if (!dr)
		return -ENOMEM;

	dr->bRequestType= requesttype;
	dr->bRequest = request;
	dr->wValue = cpu_to_le16p(&value);
	dr->wIndex = cpu_to_le16p(&index);
	dr->wLength = cpu_to_le16p(&size);

	//dbg("usb_control_msg");	

	ret = usb_internal_control_msg(dev, pipe, dr, data, size, timeout);

	kfree(dr);

	return ret;
}


/**
 *	usb_bulk_msg - Builds a bulk urb, sends it off and waits for completion
 *	@usb_dev: pointer to the usb device to send the message to
 *	@pipe: endpoint "pipe" to send the message to
 *	@data: pointer to the data to send
 *	@len: length in bytes of the data to send
 *	@actual_length: pointer to a location to put the actual length transferred in bytes
 *	@timeout: time in jiffies to wait for the message to complete before
 *		timing out (if 0 the wait is forever)
 *	Context: !in_interrupt ()
 *
 *	This function sends a simple bulk message to a specified endpoint
 *	and waits for the message to complete, or timeout.
 *	
 *	If successful, it returns 0, otherwise a negative error number.
 *	The number of actual bytes transferred will be stored in the 
 *	actual_length paramater.
 *
 *	Don't use this function from within an interrupt context, like a
 *	bottom half handler.  If you need an asynchronous message, or need to
 *	send a message from within interrupt context, use usb_submit_urb()
 *      If a thread in your driver uses this call, make sure your disconnect()
 *      method can wait for it to complete.  Since you don't have a handle on
 *      the URB used, you can't cancel the request.
 */
int usb_bulk_msg(struct usb_device *usb_dev, unsigned int pipe, 
			void *data, int len, int *actual_length, int timeout)
{
	struct urb *urb;

	if (len < 0)
		return -EINVAL;

	urb=usb_alloc_urb(0, GFP_KERNEL);
	if (!urb)
		return -ENOMEM;

	usb_fill_bulk_urb(urb, usb_dev, pipe, data, len,
			  usb_api_blocking_completion, NULL);

	return usb_start_wait_urb(urb,timeout,actual_length);
}

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

static void sg_clean (struct usb_sg_request *io)
{
	if (io->urbs) {
		while (io->entries--)
			usb_free_urb (io->urbs [io->entries]);
		kfree (io->urbs);
		io->urbs = NULL;
	}
	if (io->dev->dev.dma_mask != NULL)
		usb_buffer_unmap_sg (io->dev, io->pipe, io->sg, io->nents);
	io->dev = NULL;
}

static void sg_complete (struct urb *urb, struct pt_regs *regs)
{
	struct usb_sg_request	*io = (struct usb_sg_request *) urb->context;

	spin_lock (&io->lock);

	/* In 2.5 we require hcds' endpoint queues not to progress after fault
	 * reports, until the completion callback (this!) returns.  That lets
	 * device driver code (like this routine) unlink queued urbs first,
	 * if it needs to, since the HC won't work on them at all.  So it's
	 * not possible for page N+1 to overwrite page N, and so on.
	 *
	 * That's only for "hard" faults; "soft" faults (unlinks) sometimes
	 * complete before the HCD can get requests away from hardware,
	 * though never during cleanup after a hard fault.
	 */
	if (io->status
			&& (io->status != -ECONNRESET
				|| urb->status != -ECONNRESET)
			&& urb->actual_length) {
		dev_err (io->dev->bus->controller,
			"dev %s ep%d%s scatterlist error %d/%d\n",
			io->dev->devpath,
			usb_pipeendpoint (urb->pipe),
			usb_pipein (urb->pipe) ? "in" : "out",
			urb->status, io->status);
		// BUG ();
	}

	if (io->status == 0 && urb->status && urb->status != -ECONNRESET) {
		int		i, found, status;

		io->status = urb->status;

		/* the previous urbs, and this one, completed already.
		 * unlink pending urbs so they won't rx/tx bad data.
		 * careful: unlink can sometimes be synchronous...
		 */
		spin_unlock (&io->lock);
		for (i = 0, found = 0; i < io->entries; i++) {
			if (!io->urbs [i] || !io->urbs [i]->dev)
				continue;
			if (found) {
				status = usb_unlink_urb (io->urbs [i]);
				if (status != -EINPROGRESS && status != -EBUSY)
					dev_err (&io->dev->dev,
						"%s, unlink --> %d\n",
						__FUNCTION__, status);
			} else if (urb == io->urbs [i])
				found = 1;
		}
		spin_lock (&io->lock);
	}
	urb->dev = NULL;

	/* on the last completion, signal usb_sg_wait() */
	io->bytes += urb->actual_length;
	io->count--;
	if (!io->count)
		complete (&io->complete);

	spin_unlock (&io->lock);
}


/**
 * usb_sg_init - initializes scatterlist-based bulk/interrupt I/O request
 * @io: request block being initialized.  until usb_sg_wait() returns,
 *	treat this as a pointer to an opaque block of memory,
 * @dev: the usb device that will send or receive the data
 * @pipe: endpoint "pipe" used to transfer the data
 * @period: polling rate for interrupt endpoints, in frames or
 * 	(for high speed endpoints) microframes; ignored for bulk
 * @sg: scatterlist entries
 * @nents: how many entries in the scatterlist
 * @length: how many bytes to send from the scatterlist, or zero to
 * 	send every byte identified in the list.
 * @mem_flags: SLAB_* flags affecting memory allocations in this call
 *
 * Returns zero for success, else a negative errno value.  This initializes a
 * scatter/gather request, allocating resources such as I/O mappings and urb
 * memory (except maybe memory used by USB controller drivers).
 *
 * The request must be issued using usb_sg_wait(), which waits for the I/O to
 * complete (or to be canceled) and then cleans up all resources allocated by
 * usb_sg_init().
 *
 * The request may be canceled with usb_sg_cancel(), either before or after
 * usb_sg_wait() is called.
 */
int usb_sg_init (
	struct usb_sg_request	*io,
	struct usb_device	*dev,
	unsigned		pipe, 
	unsigned		period,
	struct scatterlist	*sg,
	int			nents,
	size_t			length,
	int			mem_flags
)
{
	int			i;
	int			urb_flags;
	int			dma;

	if (!io || !dev || !sg
			|| usb_pipecontrol (pipe)
			|| usb_pipeisoc (pipe)
			|| nents <= 0)
		return -EINVAL;

	spin_lock_init (&io->lock);
	io->dev = dev;
	io->pipe = pipe;
	io->sg = sg;
	io->nents = nents;

	/* not all host controllers use DMA (like the mainstream pci ones);
	 * they can use PIO (sl811) or be software over another transport.
	 */
	dma = (dev->dev.dma_mask != NULL);
	if (dma)
		io->entries = usb_buffer_map_sg (dev, pipe, sg, nents);
	else
		io->entries = nents;

	/* initialize all the urbs we'll use */
	if (io->entries <= 0)
		return io->entries;

	io->count = io->entries;
	io->urbs = kmalloc (io->entries * sizeof *io->urbs, mem_flags);
	if (!io->urbs)
		goto nomem;

	urb_flags = URB_ASYNC_UNLINK | URB_NO_TRANSFER_DMA_MAP
			| URB_NO_INTERRUPT;
	if (usb_pipein (pipe))
		urb_flags |= URB_SHORT_NOT_OK;

	for (i = 0; i < io->entries; i++) {
		unsigned		len;

		io->urbs [i] = usb_alloc_urb (0, mem_flags);
		if (!io->urbs [i]) {
			io->entries = i;
			goto nomem;
		}

		io->urbs [i]->dev = NULL;
		io->urbs [i]->pipe = pipe;
		io->urbs [i]->interval = period;
		io->urbs [i]->transfer_flags = urb_flags;

		io->urbs [i]->complete = sg_complete;
		io->urbs [i]->context = io;
		io->urbs [i]->status = -EINPROGRESS;
		io->urbs [i]->actual_length = 0;

		if (dma) {
			/* hc may use _only_ transfer_dma */
			io->urbs [i]->transfer_dma = sg_dma_address (sg + i);
			len = sg_dma_len (sg + i);
		} else {
			/* hc may use _only_ transfer_buffer */
			io->urbs [i]->transfer_buffer =
				page_address (sg [i].page) + sg [i].offset;
			len = sg [i].length;
		}

		if (length) {
			len = min_t (unsigned, len, length);
			length -= len;
			if (length == 0)
				io->entries = i + 1;
		}
		io->urbs [i]->transfer_buffer_length = len;
	}
	io->urbs [--i]->transfer_flags &= ~URB_NO_INTERRUPT;

	/* transaction state */
	io->status = 0;
	io->bytes = 0;
	init_completion (&io->complete);
	return 0;

nomem:
	sg_clean (io);
	return -ENOMEM;
}


/**
 * usb_sg_wait - synchronously execute scatter/gather request
 * @io: request block handle, as initialized with usb_sg_init().
 * 	some fields become accessible when this call returns.
 * Context: !in_interrupt ()
 *
 * This function blocks until the specified I/O operation completes.  It
 * leverages the grouping of the related I/O requests to get good transfer
 * rates, by queueing the requests.  At higher speeds, such queuing can
 * significantly improve USB throughput.
 *
 * There are three kinds of completion for this function.
 * (1) success, where io->status is zero.  The number of io->bytes
 *     transferred is as requested.
 * (2) error, where io->status is a negative errno value.  The number
 *     of io->bytes transferred before the error is usually less
 *     than requested, and can be nonzero.
 * (3) cancelation, a type of error with status -ECONNRESET that
 *     is initiated by usb_sg_cancel().
 *
 * When this function returns, all memory allocated through usb_sg_init() or
 * this call will have been freed.  The request block parameter may still be
 * passed to usb_sg_cancel(), or it may be freed.  It could also be
 * reinitialized and then reused.
 *
 * Data Transfer Rates:
 *
 * Bulk transfers are valid for full or high speed endpoints.
 * The best full speed data rate is 19 packets of 64 bytes each
 * per frame, or 1216 bytes per millisecond.
 * The best high speed data rate is 13 packets of 512 bytes each
 * per microframe, or 52 KBytes per millisecond.
 *
 * The reason to use interrupt transfers through this API would most likely
 * be to reserve high speed bandwidth, where up to 24 KBytes per millisecond
 * could be transferred.  That capability is less useful for low or full
 * speed interrupt endpoints, which allow at most one packet per millisecond,
 * of at most 8 or 64 bytes (respectively).
 */
void usb_sg_wait (struct usb_sg_request *io)
{
	int		i, entries = io->entries;

	/* queue the urbs.  */
	spin_lock_irq (&io->lock);
	for (i = 0; i < entries && !io->status; i++) {
		int	retval;

		io->urbs [i]->dev = io->dev;
		retval = usb_submit_urb (io->urbs [i], SLAB_ATOMIC);

		/* after we submit, let completions or cancelations fire;
		 * we handshake using io->status.
		 */
		spin_unlock_irq (&io->lock);
		switch (retval) {
			/* maybe we retrying will recover */
		case -ENXIO:	// hc didn't queue this one
		case -EAGAIN:
		case -ENOMEM:
			io->urbs[i]->dev = NULL;
			retval = 0;
			i--;
			yield ();
			break;

			/* no error? continue immediately.
			 *
			 * NOTE: to work better with UHCI (4K I/O buffer may
			 * need 3K of TDs) it may be good to limit how many
			 * URBs are queued at once; N milliseconds?
			 */