Demos/Host/LowLevel/AndroidAccessoryHost/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 /** 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 the first interface containing bulk IN and OUT data endpoints.
  45  *
  46  *  \return An error code from the \ref AndroidHost_GetConfigDescriptorDataCodes_t enum.
  47  */
  48 uint8_t ProcessConfigurationDescriptor(void)
  49 {
  50         uint8_t  ConfigDescriptorData[512];
  51         void*    CurrConfigLocation = ConfigDescriptorData;
  52         uint16_t CurrConfigBytesRem;
  53
  54         USB_Descriptor_Endpoint_t* DataINEndpoint  = NULL;
  55         USB_Descriptor_Endpoint_t* DataOUTEndpoint = NULL;
  56
  57         /* Retrieve the entire configuration descriptor into the allocated buffer */
  58         switch (USB_Host_GetDeviceConfigDescriptor(1, &CurrConfigBytesRem, ConfigDescriptorData, sizeof(ConfigDescriptorData)))
  59         {
  60                 case HOST_GETCONFIG_Successful:
  61                         break;
  62                 case HOST_GETCONFIG_InvalidData:
  63                         return InvalidConfigDataReturned;
  64                 case HOST_GETCONFIG_BuffOverflow:
  65                         return DescriptorTooLarge;
  66                 default:
  67                         return DevControlError;
  68         }
  69
  70         /* There should be only one compatible Android Accessory Mode interface in the device, attempt to find it */
  71         if (USB_GetNextDescriptorComp(&CurrConfigBytesRem, &CurrConfigLocation,
  72                                       DCOMP_NextAndroidAccessoryInterface) != DESCRIPTOR_SEARCH_COMP_Found)
  73         {
  74                 return NoCompatibleInterfaceFound;
  75         }
  76
  77         while (!(DataINEndpoint) || !(DataOUTEndpoint))
  78         {
  79                 /* Get the next Android Accessory Mode interface's data endpoint descriptor */
  80                 if (USB_GetNextDescriptorComp(&CurrConfigBytesRem, &CurrConfigLocation,
  81                                               DCOMP_NextInterfaceBulkEndpoint) != DESCRIPTOR_SEARCH_COMP_Found)
  82                 {
  83                         /* Data endpoints not found within the first Android Accessory device interface, error out */
  84                         return NoCompatibleInterfaceFound;
  85                 }
  86
  87                 /* Retrieve the endpoint address from the endpoint descriptor */
  88                 USB_Descriptor_Endpoint_t* EndpointData = DESCRIPTOR_PCAST(CurrConfigLocation, USB_Descriptor_Endpoint_t);
  89
  90                 /* If the endpoint is a IN type endpoint */
  91                 if ((EndpointData->EndpointAddress & ENDPOINT_DIR_MASK) == ENDPOINT_DIR_IN)
  92                   DataINEndpoint  = EndpointData;
  93                 else
  94                   DataOUTEndpoint = EndpointData;
  95         }
  96
  97         /* Configure the Android Accessory data IN pipe */
  98         Pipe_ConfigurePipe(ANDROID_DATA_IN_PIPE, EP_TYPE_BULK, DataINEndpoint->EndpointAddress, DataINEndpoint->EndpointSize, 1);
  99
 100         /* Configure the Android Accessory data OUT pipe */
 101         Pipe_ConfigurePipe(ANDROID_DATA_OUT_PIPE, EP_TYPE_BULK, DataOUTEndpoint->EndpointAddress, DataOUTEndpoint->EndpointSize, 1);
 102
 103         /* Valid data found, return success */
 104         return SuccessfulConfigRead;
 105 }
 106
 107 /** Descriptor comparator function. This comparator function is can be called while processing an attached USB device's
 108  *  configuration descriptor, to search for a specific sub descriptor. It can also be used to abort the configuration
 109  *  descriptor processing if an incompatible descriptor configuration is found.
 110  *
 111  *  This comparator searches for the next Interface descriptor containing the correct Android Accessory Mode Class, Subclass
 112  *  and Protocol values.
 113  *
 114  *  \return A value from the DSEARCH_Return_ErrorCodes_t enum
 115  */
 116 uint8_t DCOMP_NextAndroidAccessoryInterface(void* const CurrentDescriptor)
 117 {
 118         USB_Descriptor_Header_t* Header = DESCRIPTOR_PCAST(CurrentDescriptor, USB_Descriptor_Header_t);
 119
 120         if (Header->Type == DTYPE_Interface)
 121         {
 122                 USB_Descriptor_Interface_t* Interface = DESCRIPTOR_PCAST(CurrentDescriptor, USB_Descriptor_Interface_t);
 123
 124                 if ((Interface->Class    == AOA_CSCP_AOADataClass)    &&
 125                     (Interface->SubClass == AOA_CSCP_AOADataSubclass) &&
 126                     (Interface->Protocol == AOA_CSCP_AOADataProtocol))
 127                 {
 128                         return DESCRIPTOR_SEARCH_Found;
 129                 }
 130         }
 131
 132         return DESCRIPTOR_SEARCH_NotFound;
 133 }
 134
 135 /** Descriptor comparator function. This comparator function is can be called while processing an attached USB device's
 136  *  configuration descriptor, to search for a specific sub descriptor. It can also be used to abort the configuration
 137  *  descriptor processing if an incompatible descriptor configuration is found.
 138  *
 139  *  This comparator searches for the next bulk Endpoint descriptor inside the current interface descriptor, aborting the
 140  *  search if another interface descriptor is found before the required endpoint.
 141  *
 142  *  \return A value from the DSEARCH_Return_ErrorCodes_t enum
 143  */
 144 uint8_t DCOMP_NextInterfaceBulkEndpoint(void* const CurrentDescriptor)
 145 {
 146         USB_Descriptor_Header_t* Header = DESCRIPTOR_PCAST(CurrentDescriptor, USB_Descriptor_Header_t);
 147
 148         if (Header->Type == DTYPE_Endpoint)
 149         {
 150                 USB_Descriptor_Endpoint_t* Endpoint = DESCRIPTOR_PCAST(CurrentDescriptor, USB_Descriptor_Endpoint_t);
 151
 152                 uint8_t EndpointType = (Endpoint->Attributes & EP_TYPE_MASK);
 153
 154                 if ((EndpointType == EP_TYPE_BULK) && (!(Pipe_IsEndpointBound(Endpoint->EndpointAddress))))
 155                   return DESCRIPTOR_SEARCH_Found;
 156         }
 157         else if (Header->Type == DTYPE_Interface)
 158         {
 159                 return DESCRIPTOR_SEARCH_Fail;
 160         }
 161
 162         return DESCRIPTOR_SEARCH_NotFound;
 163 }
 164