Modules/USB/Core/usb_poll.c

   1 /*
   2  * Acess2 USB Stack
   3  * - By John Hodge (thePowersGang)
   4  *
   5  * usb_poll.c
   6  * - Endpoint polling
   7  */
   8 #define DEBUG   1
   9 #include <usb_core.h>
  10 #include "usb.h"
  11
  12 #define POLL_ATOM       25      // 25ms atom
  13 #define POLL_MAX        256     // Max period that can be nominated
  14 #define POLL_SLOTS      ((int)(POLL_MAX/POLL_ATOM))
  15
  16 // === PROTOTYPES ===
  17 void    USB_StartPollingEndpoint(tUSBInterface *Iface, int Endpoint);
  18
  19 // === GLOBALS ===
  20 tUSBEndpoint    *gUSB_PollQueues[POLL_MAX/POLL_ATOM];
  21  int    giUSB_PollPosition;     // Index into gUSB_PollQueues
  22
  23 // === CODE ===
  24 void USB_StartPollingEndpoint(tUSBInterface *Iface, int Endpoint)
  25 {
  26         tUSBEndpoint    *endpt;
  27
  28         // Some sanity checks
  29         if(Endpoint <= 0 || Endpoint >= Iface->nEndpoints)      return ;
  30         endpt = &Iface->Endpoints[Endpoint-1];
  31         if(endpt->PollingPeriod > POLL_MAX || endpt->PollingPeriod <= 0)
  32                 return ;
  33
  34         // TODO: Check that this endpoint isn't already on the queue
  35
  36         // Determine polling period in atoms
  37         endpt->PollingAtoms = (endpt->PollingPeriod + POLL_ATOM-1) / POLL_ATOM;
  38         if(endpt->PollingAtoms > POLL_SLOTS)    endpt->PollingAtoms = POLL_SLOTS;
  39         // Add to poll queue
  40         endpt->Next = gUSB_PollQueues[endpt->PollingAtoms];
  41         gUSB_PollQueues[endpt->PollingAtoms] = endpt;
  42 }
  43
  44 /**
  45  * \brief USB polling thread
  46  */
  47 int USB_PollThread(void *unused)
  48 {
  49         for(;;)
  50         {
  51                 tUSBEndpoint    *ep, *prev;
  52
  53                 // A little evil for neater code
  54                 prev = (void*)( (tVAddr)&gUSB_PollQueues[giUSB_PollPosition] - offsetof(tUSBEndpoint, Next) );
  55
  56                 // Process queue
  57                 for( ep = gUSB_PollQueues[giUSB_PollPosition]; ep; prev = ep, ep = ep->Next )
  58                 {
  59                          int    period_in_atoms = ep->PollingAtoms;
  60
  61                         // Check for invalid entries
  62                         if(period_in_atoms < 0 || period_in_atoms > POLL_ATOM)
  63                         {
  64                                 Log_Warning("USB", "Endpoint on polling queue with invalid period");
  65                                 continue ;
  66                         }
  67                         // Check for entries to delete
  68                         if(period_in_atoms == 0)
  69                         {
  70                                 // Remove
  71                                 prev->Next = ep->Next;
  72                                 ep->PollingAtoms = -1;  // Mark as removed
  73                                 ep = prev;      // Make sure prev is kept valid
  74                                 continue ;
  75                         }
  76
  77                         // Read data
  78                         // TODO: Check the endpoint
  79                         // TODO: Async checking?
  80                         // - Send the read request on all of them then wait for the first to complete
  81                         // Call callback
  82
  83                         // Reschedule
  84                         if( period_in_atoms != POLL_SLOTS )
  85                         {
  86                                  int    newqueue_id = (giUSB_PollPosition + period_in_atoms) % POLL_SLOTS;
  87                                 tUSBEndpoint    **newqueue = &gUSB_PollQueues[newqueue_id];
  88
  89                                 prev->Next = ep->Next;
  90
  91                                 ep->Next = *newqueue;
  92                                 *newqueue = ep;
  93                         }
  94                 }
  95                 giUSB_PollPosition ++;
  96                 if(giUSB_PollPosition == POLL_SLOTS)
  97                         giUSB_PollPosition = 0;
  98                 // TODO: Check for a longer delay
  99                 Time_Delay(POLL_ATOM);
 100         }
 101 }
 102