Demos/Host/LowLevel/MIDIHost/ConfigDescriptor.c

   1 /*
   2              LUFA Library
   3      Copyright (C) Dean Camera, 2009.
   4
   5   dean [at] fourwalledcubicle [dot] com
   6       www.fourwalledcubicle.com
   7 */
   8
   9 /*
  10   Copyright 2009  Dean Camera (dean [at] fourwalledcubicle [dot] com)
  11
  12   Permission to use, copy, modify, and distribute this software
  13   and its documentation for any purpose and without fee is hereby
  14   granted, provided that the above copyright notice appear in all
  15   copies and that both that the copyright notice and this
  16   permission notice and warranty disclaimer appear in supporting
  17   documentation, and that the name of the author not be used in
  18   advertising or publicity pertaining to distribution of the
  19   software without specific, written prior permission.
  20
  21   The author disclaim all warranties with regard to this
  22   software, including all implied warranties of merchantability
  23   and fitness.  In no event shall the author be liable for any
  24   special, indirect or consequential damages or any damages
  25   whatsoever resulting from loss of use, data or profits, whether
  26   in an action of contract, negligence or other tortious action,
  27   arising out of or in connection with the use or performance of
  28   this software.
  29 */
  30
  31 /** \file
  32  *
  33  *  USB Device Configuration Descriptor processing routines, to determine the correct pipe configurations
  34  *  needed to communication with an attached USB device. Descriptors are special  computer-readable structures
  35  *  which the host requests upon device enumeration, to determine the device's capabilities and functions.
  36  */
  37
  38 #include "ConfigDescriptor.h"
  39
  40 /** Reads and processes an attached device's descriptors, to determine compatibility and pipe configurations. This
  41  *  routine will read in the entire configuration descriptor, and configure the hosts pipes to correctly communicate
  42  *  with compatible devices.
  43  *
  44  *  This routine searches for a MIDI interface descriptor pair containing bulk data IN and OUT endpoints.
  45  *
  46  *  \return An error code from the \ref MIDIHost_GetConfigDescriptorDataCodes_t enum.
  47  */
  48 uint8_t ProcessConfigurationDescriptor(void)
  49 {
  50         uint8_t  ConfigDescriptorData[512];
  51         uint8_t* CurrConfigLocation = ConfigDescriptorData;
  52         uint16_t CurrConfigBytesRem;
  53         uint8_t  FoundEndpoints = 0;
  54
  55         /* Retrieve the entire configuration descriptor into the allocated buffer */
  56         switch (USB_GetDeviceConfigDescriptor(1, &CurrConfigBytesRem, ConfigDescriptorData, sizeof(ConfigDescriptorData)))
  57         {
  58                 case HOST_GETCONFIG_Successful:
  59                         break;
  60                 case HOST_GETCONFIG_InvalidData:
  61                         return InvalidConfigDataReturned;
  62                 case HOST_GETCONFIG_BuffOverflow:
  63                         return DescriptorTooLarge;
  64                 default:
  65                         return ControlError;
  66         }
  67
  68         /* Get the MIDI Audio Streaming interface from the configuration descriptor */
  69         if (USB_GetNextDescriptorComp(&CurrConfigBytesRem, &CurrConfigLocation,
  70                                       DComp_NextMIDIStreamingInterface) != DESCRIPTOR_SEARCH_COMP_Found)
  71         {
  72                 /* Descriptor not found, error out */
  73                 return NoCDCInterfaceFound;
  74         }
  75
  76         /* Get the IN and OUT data endpoints for the MIDI interface */
  77         while (FoundEndpoints != ((1 << MIDI_DATAPIPE_IN) | (1 << MIDI_DATAPIPE_OUT)))
  78         {
  79                 /* Fetch the next bulk endpoint from the current MIDI streaming interface */
  80                 if (USB_GetNextDescriptorComp(&CurrConfigBytesRem, &CurrConfigLocation,
  81                                               DComp_NextMIDIStreamingDataEndpoint) != DESCRIPTOR_SEARCH_COMP_Found)
  82                 {
  83                         /* Descriptor not found, error out */
  84                         return NoEndpointFound;
  85                 }
  86
  87                 USB_Descriptor_Endpoint_t* EndpointData = DESCRIPTOR_PCAST(CurrConfigLocation, USB_Descriptor_Endpoint_t);
  88
  89                 /* Check if the endpoint is a bulk IN or bulk OUT endpoint */
  90                 if (EndpointData->EndpointAddress & ENDPOINT_DESCRIPTOR_DIR_IN)
  91                 {
  92                         /* Configure the data IN pipe */
  93                         Pipe_ConfigurePipe(MIDI_DATAPIPE_IN, EP_TYPE_BULK, PIPE_TOKEN_IN,
  94                                                            EndpointData->EndpointAddress, EndpointData->EndpointSize, PIPE_BANK_SINGLE);
  95
  96                         /* Set the flag indicating that the data IN pipe has been found */
  97                         FoundEndpoints |= (1 << MIDI_DATAPIPE_IN);
  98                 }
  99                 else
 100                 {
 101                         /* Configure the data OUT pipe */
 102                         Pipe_ConfigurePipe(MIDI_DATAPIPE_OUT, EP_TYPE_BULK, PIPE_TOKEN_OUT,
 103                                                            EndpointData->EndpointAddress, EndpointData->EndpointSize, PIPE_BANK_SINGLE);
 104
 105                         /* Set the flag indicating that the data OUT pipe has been found */
 106                         FoundEndpoints |= (1 << MIDI_DATAPIPE_OUT);
 107                 }
 108         }
 109
 110         /* Valid data found, return success */
 111         return SuccessfulConfigRead;
 112 }
 113
 114 /** Descriptor comparator function. This comparator function is can be called while processing an attached USB device's
 115  *  configuration descriptor, to search for a specific sub descriptor. It can also be used to abort the configuration
 116  *  descriptor processing if an incompatible descriptor configuration is found.
 117  *
 118  *  This comparator searches for the next Interface descriptor of the correct MIDI Streaming Class, Subclass and Protocol values.
 119  *
 120  *  \return A value from the \ref DSEARCH_Return_ErrorCodes_t enum
 121  */
 122 uint8_t DComp_NextMIDIStreamingInterface(void* CurrentDescriptor)
 123 {
 124         if (DESCRIPTOR_TYPE(CurrentDescriptor) == DTYPE_Interface)
 125         {
 126                 /* Check the MIDI descriptor class, subclass and protocol, break out if correct data interface found */
 127                 if ((DESCRIPTOR_CAST(CurrentDescriptor, USB_Descriptor_Interface_t).Class    == MIDI_STREAMING_CLASS)    &&
 128                     (DESCRIPTOR_CAST(CurrentDescriptor, USB_Descriptor_Interface_t).SubClass == MIDI_STREAMING_SUBCLASS) &&
 129                     (DESCRIPTOR_CAST(CurrentDescriptor, USB_Descriptor_Interface_t).Protocol == MIDI_STREAMING_PROTOCOL))
 130                 {
 131                         return DESCRIPTOR_SEARCH_Found;
 132                 }
 133         }
 134
 135         return DESCRIPTOR_SEARCH_NotFound;
 136 }
 137
 138 /** Descriptor comparator function. This comparator function is can be called while processing an attached USB device's
 139  *  configuration descriptor, to search for a specific sub descriptor. It can also be used to abort the configuration
 140  *  descriptor processing if an incompatible descriptor configuration is found.
 141  *
 142  *  This comparator searches for the next bulk IN or OUT endpoint within the current interface, aborting the search if
 143  *  another interface descriptor is found before the required endpoint.
 144  *
 145  *  \return A value from the \ref DSEARCH_Return_ErrorCodes_t enum
 146  */
 147 uint8_t DComp_NextMIDIStreamingDataEndpoint(void* CurrentDescriptor)
 148 {
 149         if (DESCRIPTOR_TYPE(CurrentDescriptor) == DTYPE_Endpoint)
 150         {
 151                 uint8_t EndpointType = (DESCRIPTOR_CAST(CurrentDescriptor,
 152                                                         USB_Descriptor_Endpoint_t).Attributes & EP_TYPE_MASK);
 153
 154                 /* Check the endpoint type, break out if correct BULK type endpoint found */
 155                 if (EndpointType == EP_TYPE_BULK)
 156                   return DESCRIPTOR_SEARCH_Found;
 157         }
 158         else if (DESCRIPTOR_TYPE(CurrentDescriptor) == DTYPE_Interface)
 159         {
 160                 return DESCRIPTOR_SEARCH_Fail;
 161         }
 162
 163         return DESCRIPTOR_SEARCH_NotFound;
 164 }