protocol/lufa/LUFA-git/Demos/Host/LowLevel/AudioOutputHost/ConfigDescriptor.c

   1 /*
   2              LUFA Library
   3      Copyright (C) Dean Camera, 2014.
   4
   5   dean [at] fourwalledcubicle [dot] com
   6            www.lufa-lib.org
   7 */
   8
   9 /*
  10   Copyright 2014  Dean Camera (dean [at] fourwalledcubicle [dot] com)
  11
  12   Permission to use, copy, modify, distribute, and sell this
  13   software and its documentation for any purpose is hereby granted
  14   without fee, provided that the above copyright notice appear in
  15   all 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 disclaims 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 /** Index of the currently used Audio Streaming Interface within the device. */
  41 uint8_t StreamingInterfaceIndex      = 0;
  42
  43 /** Alternative Setting of the currently used Audio Streaming Interface within the device. */
  44 uint8_t StreamingInterfaceAltSetting = 0;
  45
  46 /** Address of the streaming audio endpoint currently in use within the device. */
  47 uint8_t StreamingEndpointAddress     = 0;
  48
  49
  50 /** Reads and processes an attached device's descriptors, to determine compatibility and pipe configurations. This
  51  *  routine will read in the entire configuration descriptor, and configure the hosts pipes to correctly communicate
  52  *  with compatible devices.
  53  *
  54  *  This routine searches for a Streaming Audio interface descriptor containing a valid Isochronous audio endpoint.
  55  *
  56  *  \return An error code from the \ref AudioHost_GetConfigDescriptorDataCodes_t enum.
  57  */
  58 uint8_t ProcessConfigurationDescriptor(void)
  59 {
  60         uint8_t  ConfigDescriptorData[512];
  61         void*    CurrConfigLocation = ConfigDescriptorData;
  62         uint16_t CurrConfigBytesRem;
  63
  64         USB_Descriptor_Interface_t* AudioControlInterface   = NULL;
  65         USB_Descriptor_Interface_t* AudioStreamingInterface = NULL;
  66         USB_Descriptor_Endpoint_t*  DataOUTEndpoint         = NULL;
  67
  68         /* Retrieve the entire configuration descriptor into the allocated buffer */
  69         switch (USB_Host_GetDeviceConfigDescriptor(1, &CurrConfigBytesRem, ConfigDescriptorData, sizeof(ConfigDescriptorData)))
  70         {
  71                 case HOST_GETCONFIG_Successful:
  72                         break;
  73                 case HOST_GETCONFIG_InvalidData:
  74                         return InvalidConfigDataReturned;
  75                 case HOST_GETCONFIG_BuffOverflow:
  76                         return DescriptorTooLarge;
  77                 default:
  78                         return ControlError;
  79         }
  80
  81         while (!(DataOUTEndpoint))
  82         {
  83                 /* See if we've found a likely compatible interface, and if there is an endpoint within that interface */
  84                 if (!(AudioControlInterface) ||
  85                     USB_GetNextDescriptorComp(&CurrConfigBytesRem, &CurrConfigLocation,
  86                                               DComp_NextAudioInterfaceDataEndpoint) != DESCRIPTOR_SEARCH_COMP_Found)
  87                 {
  88                         /* Check if we haven't found an Audio Control interface yet, or if we have run out of related Audio Streaming interfaces */
  89                         if (!(AudioControlInterface) ||
  90                             USB_GetNextDescriptorComp(&CurrConfigBytesRem, &CurrConfigLocation,
  91                                                           DComp_NextAudioStreamInterface) != DESCRIPTOR_SEARCH_COMP_Found)
  92                         {
  93                                 /* Find a new Audio Control interface if the current one doesn't contain a compatible streaming interface */
  94                                 if (USB_GetNextDescriptorComp(&CurrConfigBytesRem, &CurrConfigLocation,
  95                                                               DComp_NextAudioControlInterface) != DESCRIPTOR_SEARCH_COMP_Found)
  96                                 {
  97                                         /* Descriptor not found, error out */
  98                                         return NoCompatibleInterfaceFound;
  99                                 }
 100
 101                                 /* Save the interface in case we need to refer back to it later */
 102                                 AudioControlInterface = DESCRIPTOR_PCAST(CurrConfigLocation, USB_Descriptor_Interface_t);
 103
 104                                 /* Find the next Audio Streaming interface within that Audio Control interface */
 105                                 if (USB_GetNextDescriptorComp(&CurrConfigBytesRem, &CurrConfigLocation,
 106                                                               DComp_NextAudioStreamInterface) != DESCRIPTOR_SEARCH_COMP_Found)
 107                                 {
 108                                         /* Descriptor not found, error out */
 109                                         return NoCompatibleInterfaceFound;
 110                                 }
 111                         }
 112
 113                         /* Save the interface in case we need to refer back to it later */
 114                         AudioStreamingInterface = DESCRIPTOR_PCAST(CurrConfigLocation, USB_Descriptor_Interface_t);
 115
 116                         /* Skip the remainder of the loop as we have not found an endpoint yet */
 117                         continue;
 118                 }
 119
 120                 /* Retrieve the endpoint address from the endpoint descriptor */
 121                 USB_Descriptor_Endpoint_t* EndpointData = DESCRIPTOR_PCAST(CurrConfigLocation, USB_Descriptor_Endpoint_t);
 122
 123                 /* Save the endpoint if it is an OUT type endpoint */
 124                 if ((EndpointData->EndpointAddress & ENDPOINT_DIR_MASK) == ENDPOINT_DIR_OUT)
 125                   DataOUTEndpoint = EndpointData;
 126         }
 127
 128         StreamingInterfaceIndex      = AudioStreamingInterface->InterfaceNumber;
 129         StreamingInterfaceAltSetting = AudioStreamingInterface->AlternateSetting;
 130         StreamingEndpointAddress     = DataOUTEndpoint->EndpointAddress;
 131
 132         /* Configure the Audio data OUT pipe */
 133         Pipe_ConfigurePipe(AUDIO_DATA_OUT_PIPE, EP_TYPE_ISOCHRONOUS, DataOUTEndpoint->EndpointAddress, DataOUTEndpoint->EndpointSize, 2);
 134
 135         /* Valid data found, return success */
 136         return SuccessfulConfigRead;
 137 }
 138
 139 /** Descriptor comparator function. This comparator function is can be called while processing an attached USB device's
 140  *  configuration descriptor, to search for a specific sub descriptor. It can also be used to abort the configuration
 141  *  descriptor processing if an incompatible descriptor configuration is found.
 142  *
 143  *  This comparator searches for the next Interface descriptor of the correct Audio Control Class, Subclass and Protocol values.
 144  *
 145  *  \return A value from the DSEARCH_Return_ErrorCodes_t enum
 146  */
 147 uint8_t DComp_NextAudioControlInterface(void* CurrentDescriptor)
 148 {
 149         USB_Descriptor_Header_t* Header = DESCRIPTOR_PCAST(CurrentDescriptor, USB_Descriptor_Header_t);
 150
 151         if (Header->Type == DTYPE_Interface)
 152         {
 153                 USB_Descriptor_Interface_t* Interface = DESCRIPTOR_PCAST(CurrentDescriptor, USB_Descriptor_Interface_t);
 154
 155                 if ((Interface->Class    == AUDIO_CSCP_AudioClass) &&
 156                     (Interface->SubClass == AUDIO_CSCP_ControlSubclass) &&
 157                     (Interface->Protocol == AUDIO_CSCP_ControlProtocol))
 158                 {
 159                         return DESCRIPTOR_SEARCH_Found;
 160                 }
 161         }
 162
 163         return DESCRIPTOR_SEARCH_NotFound;
 164 }
 165
 166 /** Descriptor comparator function. This comparator function is can be called while processing an attached USB device's
 167  *  configuration descriptor, to search for a specific sub descriptor. It can also be used to abort the configuration
 168  *  descriptor processing if an incompatible descriptor configuration is found.
 169  *
 170  *  This comparator searches for the next Interface descriptor of the correct Audio Streaming Class, Subclass and Protocol values.
 171  *
 172  *  \return A value from the DSEARCH_Return_ErrorCodes_t enum
 173  */
 174 uint8_t DComp_NextAudioStreamInterface(void* CurrentDescriptor)
 175 {
 176         USB_Descriptor_Header_t* Header = DESCRIPTOR_PCAST(CurrentDescriptor, USB_Descriptor_Header_t);
 177
 178         if (Header->Type == DTYPE_Interface)
 179         {
 180                 USB_Descriptor_Interface_t* Interface = DESCRIPTOR_PCAST(CurrentDescriptor, USB_Descriptor_Interface_t);
 181
 182                 if ((Interface->Class    == AUDIO_CSCP_AudioClass) &&
 183                     (Interface->SubClass == AUDIO_CSCP_AudioStreamingSubclass) &&
 184                     (Interface->Protocol == AUDIO_CSCP_StreamingProtocol))
 185                 {
 186                         return DESCRIPTOR_SEARCH_Found;
 187                 }
 188         }
 189
 190         return DESCRIPTOR_SEARCH_NotFound;
 191 }
 192
 193 /** Descriptor comparator function. This comparator function is can be called while processing an attached USB device's
 194  *  configuration descriptor, to search for a specific sub descriptor. It can also be used to abort the configuration
 195  *  descriptor processing if an incompatible descriptor configuration is found.
 196  *
 197  *  This comparator searches for the next Isochronous Endpoint descriptor within the current interface, aborting the
 198  *  search if another interface descriptor is found before the next endpoint.
 199  *
 200  *  \return A value from the DSEARCH_Return_ErrorCodes_t enum
 201  */
 202 uint8_t DComp_NextAudioInterfaceDataEndpoint(void* CurrentDescriptor)
 203 {
 204         USB_Descriptor_Header_t* Header = DESCRIPTOR_PCAST(CurrentDescriptor, USB_Descriptor_Header_t);
 205
 206         if (Header->Type == DTYPE_Endpoint)
 207         {
 208                 USB_Descriptor_Endpoint_t* Endpoint = DESCRIPTOR_PCAST(CurrentDescriptor, USB_Descriptor_Endpoint_t);
 209
 210                 if ((Endpoint->Attributes & EP_TYPE_MASK) == EP_TYPE_ISOCHRONOUS)
 211                   return DESCRIPTOR_SEARCH_Found;
 212         }
 213         else if (Header->Type == DTYPE_Interface)
 214         {
 215                 return DESCRIPTOR_SEARCH_Fail;
 216         }
 217
 218         return DESCRIPTOR_SEARCH_NotFound;
 219 }
 220