Demos/Host/LowLevel/GenericHIDHost/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 GenericHIDHost_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 ControlError;
  68         }
  69
  70         /* Get the first HID interface from the configuration descriptor */
  71         if (USB_GetNextDescriptorComp(&CurrConfigBytesRem, &CurrConfigLocation,
  72                                       DComp_NextHIDInterface) != DESCRIPTOR_SEARCH_COMP_Found)
  73         {
  74                 /* Descriptor not found, error out */
  75                 return NoCompatibleInterfaceFound;
  76         }
  77
  78         while (!(DataINEndpoint) || !(DataOUTEndpoint))
  79         {
  80                 /* Get the next HID interface's data endpoint descriptor */
  81                 if (USB_GetNextDescriptorComp(&CurrConfigBytesRem, &CurrConfigLocation,
  82                                               DComp_NextHIDInterfaceDataEndpoint) != DESCRIPTOR_SEARCH_COMP_Found)
  83                 {
  84                         /* Not all HID devices have an OUT endpoint - if we've reached the end of the HID descriptor
  85                          * but only found the mandatory IN endpoint, it's safe to continue with the device enumeration */
  86                         if (DataINEndpoint)
  87                           break;
  88
  89                         /* Clear any found endpoints */
  90                         DataOUTEndpoint = NULL;
  91
  92                         /* Get the next HID interface from the configuration descriptor */
  93                         if (USB_GetNextDescriptorComp(&CurrConfigBytesRem, &CurrConfigLocation,
  94                                                                                   DComp_NextHIDInterface) != DESCRIPTOR_SEARCH_COMP_Found)
  95                         {
  96                                 /* Descriptor not found, error out */
  97                                 return NoCompatibleInterfaceFound;
  98                         }
  99
 100                         /* Skip the remainder of the loop as we have not found an endpoint yet */
 101                         continue;
 102                 }
 103
 104                 /* Retrieve the endpoint address from the endpoint descriptor */
 105                 USB_Descriptor_Endpoint_t* EndpointData = DESCRIPTOR_PCAST(CurrConfigLocation, USB_Descriptor_Endpoint_t);
 106
 107                 /* If the endpoint is a IN type endpoint */
 108                 if (EndpointData->EndpointAddress & ENDPOINT_DESCRIPTOR_DIR_IN)
 109                   DataINEndpoint = EndpointData;
 110                 else
 111                   DataOUTEndpoint = EndpointData;
 112         }
 113
 114         /* Configure the HID data IN pipe */
 115         Pipe_ConfigurePipe(HID_DATA_IN_PIPE, EP_TYPE_INTERRUPT, PIPE_TOKEN_IN,
 116                            DataINEndpoint->EndpointAddress, DataINEndpoint->EndpointSize, PIPE_BANK_SINGLE);
 117         Pipe_SetInterruptPeriod(DataINEndpoint->PollingIntervalMS);
 118
 119         /* Check if the HID interface contained an optional OUT data endpoint */
 120         if (DataOUTEndpoint)
 121         {
 122                 /* Configure the HID data OUT pipe */
 123                 Pipe_ConfigurePipe(HID_DATA_OUT_PIPE, EP_TYPE_INTERRUPT, PIPE_TOKEN_OUT,
 124                                                    DataOUTEndpoint->EndpointAddress, DataOUTEndpoint->EndpointSize, PIPE_BANK_SINGLE);
 125         }
 126
 127         /* Valid data found, return success */
 128         return SuccessfulConfigRead;
 129 }
 130
 131 /** Descriptor comparator function. This comparator function is can be called while processing an attached USB device's
 132  *  configuration descriptor, to search for a specific sub descriptor. It can also be used to abort the configuration
 133  *  descriptor processing if an incompatible descriptor configuration is found.
 134  *
 135  *  This comparator searches for the next Interface descriptor of the correct HID Class value.
 136  *
 137  *  \return A value from the DSEARCH_Return_ErrorCodes_t enum
 138  */
 139 uint8_t DComp_NextHIDInterface(void* CurrentDescriptor)
 140 {
 141         /* Determine if the current descriptor is an interface descriptor */
 142         if (DESCRIPTOR_TYPE(CurrentDescriptor) == DTYPE_Interface)
 143         {
 144                 /* Check the HID descriptor class, break out if correct class/protocol interface found */
 145                 if (DESCRIPTOR_CAST(CurrentDescriptor, USB_Descriptor_Interface_t).Class == HID_CLASS)
 146                 {
 147                         /* Indicate that the descriptor being searched for has been found */
 148                         return DESCRIPTOR_SEARCH_Found;
 149                 }
 150         }
 151
 152         /* Current descriptor does not match what this comparator is looking for */
 153         return DESCRIPTOR_SEARCH_NotFound;
 154 }
 155
 156 /** Descriptor comparator function. This comparator function is can be called while processing an attached USB device's
 157  *  configuration descriptor, to search for a specific sub descriptor. It can also be used to abort the configuration
 158  *  descriptor processing if an incompatible descriptor configuration is found.
 159  *
 160  *  This comparator searches for the next Endpoint descriptor inside the current interface descriptor,
 161  *  aborting the search if another interface descriptor is found before the required endpoint.
 162  *
 163  *  \return A value from the DSEARCH_Return_ErrorCodes_t enum
 164  */
 165 uint8_t DComp_NextHIDInterfaceDataEndpoint(void* CurrentDescriptor)
 166 {
 167         /* Determine the type of the current descriptor */
 168         if (DESCRIPTOR_TYPE(CurrentDescriptor) == DTYPE_Endpoint)
 169         {
 170                 /* Indicate that the descriptor being searched for has been found */
 171                 return DESCRIPTOR_SEARCH_Found;
 172         }
 173         else if (DESCRIPTOR_TYPE(CurrentDescriptor) == DTYPE_Interface)
 174         {
 175                 /* Indicate that the search has failed prematurely and should be aborted */
 176                 return DESCRIPTOR_SEARCH_Fail;
 177         }
 178
 179         /* Current descriptor does not match what this comparator is looking for */
 180         return DESCRIPTOR_SEARCH_NotFound;
 181 }