Demos/Host/LowLevel/GenericHIDHost/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 HID interface descriptor containing at least one Interrupt type IN endpoint.
  45  *
  46  *  \return An error code from the \ref GenericHIDHost_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 HID interface from the configuration descriptor */
  69         if (USB_GetNextDescriptorComp(&CurrConfigBytesRem, &CurrConfigLocation,
  70                                       DComp_NextHIDInterface) != DESCRIPTOR_SEARCH_COMP_Found)
  71         {
  72                 /* Descriptor not found, error out */
  73                 return NoHIDInterfaceFound;
  74         }
  75
  76         while (FoundEndpoints != ((1 << HID_DATA_IN_PIPE) | (1 << HID_DATA_OUT_PIPE)))
  77         {
  78                 /* Get the next HID interface's data endpoint descriptor */
  79                 if (USB_GetNextDescriptorComp(&CurrConfigBytesRem, &CurrConfigLocation,
  80                                               DComp_NextHIDInterfaceDataEndpoint) != DESCRIPTOR_SEARCH_COMP_Found)
  81                 {
  82                         /* Not all HID devices have an OUT endpoint - if we've reached the end of the HID descriptor
  83                          * but only found the mandatory IN endpoint, it's safe to continue with the device enumeration */
  84                         if (FoundEndpoints == (1 << HID_DATA_IN_PIPE))
  85                           break;
  86
  87                         /* Descriptor not found, error out */
  88                         return NoEndpointFound;
  89                 }
  90
  91                 /* Retrieve the endpoint address from the endpoint descriptor */
  92                 USB_Descriptor_Endpoint_t* EndpointData = DESCRIPTOR_PCAST(CurrConfigLocation, USB_Descriptor_Endpoint_t);
  93
  94                 /* If the endpoint is a IN type endpoint */
  95                 if (EndpointData->EndpointAddress & ENDPOINT_DESCRIPTOR_DIR_IN)
  96                 {
  97                         /* Configure the HID data IN pipe */
  98                         Pipe_ConfigurePipe(HID_DATA_IN_PIPE, EP_TYPE_INTERRUPT, PIPE_TOKEN_IN,
  99                                                            EndpointData->EndpointAddress, EndpointData->EndpointSize, PIPE_BANK_SINGLE);
 100
 101                         FoundEndpoints |= (1 << HID_DATA_IN_PIPE);
 102                 }
 103                 else
 104                 {
 105                         /* Configure the HID data OUT pipe */
 106                         Pipe_ConfigurePipe(HID_DATA_OUT_PIPE, EP_TYPE_INTERRUPT, PIPE_TOKEN_OUT,
 107                                                            EndpointData->EndpointAddress, EndpointData->EndpointSize, PIPE_BANK_SINGLE);
 108
 109                         FoundEndpoints |= (1 << HID_DATA_OUT_PIPE);
 110                 }
 111         }
 112
 113         /* Valid data found, return success */
 114         return SuccessfulConfigRead;
 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 Interface descriptor of the correct HID Class value.
 122  *
 123  *  \return A value from the \ref DSEARCH_Return_ErrorCodes_t enum
 124  */
 125 uint8_t DComp_NextHIDInterface(void* CurrentDescriptor)
 126 {
 127         /* Determine if the current descriptor is an interface descriptor */
 128         if (DESCRIPTOR_TYPE(CurrentDescriptor) == DTYPE_Interface)
 129         {
 130                 /* Check the HID descriptor class, break out if correct class/protocol interface found */
 131                 if (DESCRIPTOR_CAST(CurrentDescriptor, USB_Descriptor_Interface_t).Class == HID_CLASS)
 132                 {
 133                         /* Indicate that the descriptor being searched for has been found */
 134                         return DESCRIPTOR_SEARCH_Found;
 135                 }
 136         }
 137
 138         /* Current descriptor does not match what this comparator is looking for */
 139         return DESCRIPTOR_SEARCH_NotFound;
 140 }
 141
 142 /** Descriptor comparator function. This comparator function is can be called while processing an attached USB device's
 143  *  configuration descriptor, to search for a specific sub descriptor. It can also be used to abort the configuration
 144  *  descriptor processing if an incompatible descriptor configuration is found.
 145  *
 146  *  This comparator searches for the next Endpoint descriptor inside the current interface descriptor,
 147  *  aborting the search if another interface descriptor is found before the required endpoint.
 148  *
 149  *  \return A value from the \ref DSEARCH_Return_ErrorCodes_t enum
 150  */
 151 uint8_t DComp_NextHIDInterfaceDataEndpoint(void* CurrentDescriptor)
 152 {
 153         /* Determine the type of the current descriptor */
 154         if (DESCRIPTOR_TYPE(CurrentDescriptor) == DTYPE_Endpoint)
 155         {
 156                 /* Indicate that the descriptor being searched for has been found */
 157                 return DESCRIPTOR_SEARCH_Found;
 158         }
 159         else if (DESCRIPTOR_TYPE(CurrentDescriptor) == DTYPE_Interface)
 160         {
 161                 /* Indicate that the search has failed prematurely and should be aborted */
 162                 return DESCRIPTOR_SEARCH_Fail;
 163         }
 164
 165         /* Current descriptor does not match what this comparator is looking for */
 166         return DESCRIPTOR_SEARCH_NotFound;
 167 }