public void Free()
{
FOS_System.Heap.Free(queueHead);
queueHead = null;
}
/// <summary>
/// Initializes a new queue head with specified underlying memory structure.
/// </summary>
/// <param name="aQueueHead">The existing underlying queue head.</param>
public EHCI_QueueHead(EHCI_QueueHead_Struct* aQueueHead)
{
queueHead = aQueueHead;
}
/// <summary>
/// Adds a transfer for the async schedule.
/// </summary>
/// <param name="transfer">The transfer to add.</param>
protected void AddToAsyncSchedule(USBTransfer transfer)
{
// Set the expected number of USB Interrupts to 1
// 1 because we expect one and only one for the last transaction of the transfer
// which we flagged to Interrupt On Complete in IssueTransfer.
USBIntCount = 1;
// If the schedule is disabled:
// Section 2.3.2 of Intel EHCI Spec
if ((USBSTS & EHCI_Consts.STS_AsyncEnabled) == 0)
{
// Enable / start the async schedule
EnableAsyncSchedule();
}
// Save the old tail queue head (which may not be the idle queue head) (save in a wrapper)
EHCI_QueueHead oldTailQH = new EHCI_QueueHead(TailQueueHead);
// The new queue head will now be end of the queue
TailQueueHead = (EHCI_QueueHead_Struct*)transfer.underlyingTransferData;
// Create wrappers for the idle and tail queue heads.
EHCI_QueueHead idleQH = new EHCI_QueueHead(IdleQueueHead);
EHCI_QueueHead tailQH = new EHCI_QueueHead(TailQueueHead);
// Create the ring. Link the new queue head with idleQH (which is always the head of the queue)
tailQH.HorizontalLinkPointer = (EHCI_QueueHead_Struct*)VirtMemManager.GetPhysicalAddress(IdleQueueHead);
// Insert the queue head into the queue as an element behind old queue head
oldTailQH.HorizontalLinkPointer = (EHCI_QueueHead_Struct*)VirtMemManager.GetPhysicalAddress(TailQueueHead);
int timeout = 100;
while (USBIntCount > 0 && (HostSystemErrors == 0) && !IrrecoverableError && --timeout > 0)
{
Kernel.Processes.SystemCalls.SleepThread(50);
#if EHCI_TRACE
if (timeout % 10 == 0)
{
BasicConsole.WriteLine("Waiting for transfer to complete...");
}
#endif
}
#if EHCI_TRACE
if (timeout == 0)
{
BasicConsole.WriteLine("Transfer timed out.");
}
#endif
// Restore the link of the old tail queue head to the idle queue head
oldTailQH.HorizontalLinkPointer = (EHCI_QueueHead_Struct*)VirtMemManager.GetPhysicalAddress(IdleQueueHead);
// Queue head done.
// Because nothing else touches the async queue and this method is a synchronous method,
// the idle queue head will now always be the end of the queue again.
TailQueueHead = oldTailQH.queueHead;
}
/// <summary>
/// Initializes a new queue head with empty underlying memory structure.
/// </summary>
public EHCI_QueueHead()
{
queueHead = (EHCI_QueueHead_Struct*)FOS_System.Heap.AllocZeroedAPB((uint)sizeof(EHCI_QueueHead_Struct), 32, "EHCI : EHCI_QueueHead()");
}
/// <summary>
/// Initialises the async schedule.
/// </summary>
protected void InitializeAsyncSchedule()
{
// If there is no idle queue head:
if (IdleQueueHead == null)
{
// Create one and set it as both the idle and tail queue heads.
IdleQueueHead = TailQueueHead = new EHCI_QueueHead().queueHead;
// The Idle Queue Head always remains in the queue and it does nothing.
// It is also always the head of the reclamation list. (Note: The
// reclamation list is not made use of by this driver implementation).
// The spec makes no explicit mention of needing an Idle Queue Head.
// However, the need is clearly implicitly there. The spec says that
// while the async queue is enabled, it will use the ASYNCLISTADDR to
// try and traverse the async queue. This clearly suggests then, that
// the ASYNCLISTADDR must be valid for the entire time that the async
// schedule is enabled. For this to be possible without continually
// sending actual transfers, we must have the idle transfer (queue head).
// Section 4.8 of Intel EHCI Spec
}
// Initialise the idle queue head as a circular list of 1 item - i.e. idle queue head
// points to itself. And as the head of the reclamation list.
InitQH(IdleQueueHead, IdleQueueHead, null, true, 0, 0, 0);
// Set the Async List Address to point to the idle queue head.
// Note: Physical address of queue head is required.
// Section 2.3.7 of Intel EHCI Spec
ASYNCLISTADDR = (EHCI_QueueHead_Struct*)VirtMemManager.GetPhysicalAddress(IdleQueueHead);
// Enable the async schedule.
EnableAsyncSchedule();
}