Demos/Host/LowLevel/KeyboardHost/ConfigDescriptor.c

   1 /*
   2              LUFA Library
   3      Copyright (C) Dean Camera, 2010.
   4
   5   dean [at] fourwalledcubicle [dot] com
   6       www.fourwalledcubicle.com
   7 */
   8
   9 /*
  10   Copyright 2010  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 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 HID interface descriptor containing at least one Interrupt type IN endpoint.
  45  *
  46  *  \return An error code from the \ref KeyboardHost_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         /* Retrieve the entire configuration descriptor into the allocated buffer */
  55         switch (USB_Host_GetDeviceConfigDescriptor(1, &CurrConfigBytesRem, ConfigDescriptorData, sizeof(ConfigDescriptorData)))
  56         {
  57                 case HOST_GETCONFIG_Successful:
  58                         break;
  59                 case HOST_GETCONFIG_InvalidData:
  60                         return InvalidConfigDataReturned;
  61                 case HOST_GETCONFIG_BuffOverflow:
  62                         return DescriptorTooLarge;
  63                 default:
  64                         return ControlError;
  65         }
  66
  67         /* Get the keyboard interface from the configuration descriptor */
  68         if (USB_GetNextDescriptorComp(&CurrConfigBytesRem, &CurrConfigLocation,
  69                                       DComp_NextKeyboardInterface) != DESCRIPTOR_SEARCH_COMP_Found)
  70         {
  71                 /* Descriptor not found, error out */
  72                 return NoHIDInterfaceFound;
  73         }
  74
  75         /* Get the keyboard interface's data endpoint descriptor */
  76         if (USB_GetNextDescriptorComp(&CurrConfigBytesRem, &CurrConfigLocation,
  77                                       DComp_NextKeyboardInterfaceDataEndpoint) != DESCRIPTOR_SEARCH_COMP_Found)
  78         {
  79                 /* Descriptor not found, error out */
  80                 return NoEndpointFound;
  81         }
  82
  83         /* Retrieve the endpoint address from the endpoint descriptor */
  84         USB_Descriptor_Endpoint_t* EndpointData = DESCRIPTOR_PCAST(CurrConfigLocation, USB_Descriptor_Endpoint_t);
  85
  86         /* Configure the keyboard data pipe */
  87         Pipe_ConfigurePipe(KEYBOARD_DATAPIPE, EP_TYPE_INTERRUPT, PIPE_TOKEN_IN,
  88                            EndpointData->EndpointAddress, EndpointData->EndpointSize, PIPE_BANK_SINGLE);
  89
  90         /* Valid data found, return success */
  91         return SuccessfulConfigRead;
  92 }
  93
  94 /** Descriptor comparator function. This comparator function is can be called while processing an attached USB device's
  95  *  configuration descriptor, to search for a specific sub descriptor. It can also be used to abort the configuration
  96  *  descriptor processing if an incompatible descriptor configuration is found.
  97  *
  98  *  This comparator searches for the next Interface descriptor of the correct Keyboard HID Class and Protocol values.
  99  *
 100  *  \return A value from the DSEARCH_Return_ErrorCodes_t enum
 101  */
 102 uint8_t DComp_NextKeyboardInterface(void* CurrentDescriptor)
 103 {
 104         if (DESCRIPTOR_TYPE(CurrentDescriptor) == DTYPE_Interface)
 105         {
 106                 /* Check the HID descriptor class and protocol, break out if correct class/protocol interface found */
 107                 if ((DESCRIPTOR_CAST(CurrentDescriptor, USB_Descriptor_Interface_t).Class    == KEYBOARD_CLASS) &&
 108                     (DESCRIPTOR_CAST(CurrentDescriptor, USB_Descriptor_Interface_t).Protocol == KEYBOARD_PROTOCOL))
 109                 {
 110                         return DESCRIPTOR_SEARCH_Found;
 111                 }
 112         }
 113
 114         return DESCRIPTOR_SEARCH_NotFound;
 115 }
 116
 117 /** Descriptor comparator function. This comparator function is can be called while processing an attached USB device's
 118  *  configuration descriptor, to search for a specific sub descriptor. It can also be used to abort the configuration
 119  *  descriptor processing if an incompatible descriptor configuration is found.
 120  *
 121  *  This comparator searches for the next IN Endpoint descriptor inside the current interface descriptor,
 122  *  aborting the search if another interface descriptor is found before the required endpoint.
 123  *
 124  *  \return A value from the DSEARCH_Return_ErrorCodes_t enum
 125  */
 126 uint8_t DComp_NextKeyboardInterfaceDataEndpoint(void* CurrentDescriptor)
 127 {
 128         if (DESCRIPTOR_TYPE(CurrentDescriptor) == DTYPE_Endpoint)
 129         {
 130                 if (DESCRIPTOR_CAST(CurrentDescriptor, USB_Descriptor_Endpoint_t).EndpointAddress & ENDPOINT_DESCRIPTOR_DIR_IN)
 131                   return DESCRIPTOR_SEARCH_Found;
 132         }
 133         else if (DESCRIPTOR_TYPE(CurrentDescriptor) == DTYPE_Interface)
 134         {
 135                 return DESCRIPTOR_SEARCH_Fail;
 136         }
 137
 138         return DESCRIPTOR_SEARCH_NotFound;
 139 }