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 GenericHIDHost_GetConfigDescriptorDataCodes_t enum.
  47  */
  48 uint8_t ProcessConfigurationDescriptor(void)
  49 {
  50         uint8_t* ConfigDescriptorData;
  51         uint16_t ConfigDescriptorSize;
  52
  53         uint8_t  FoundEndpoints = 0;
  54
  55         /* Get Configuration Descriptor size from the device */
  56         if (USB_GetDeviceConfigDescriptor(1, &ConfigDescriptorSize, NULL) != HOST_SENDCONTROL_Successful)
  57           return ControlError;
  58
  59         /* Ensure that the Configuration Descriptor isn't too large */
  60         if (ConfigDescriptorSize > MAX_CONFIG_DESCRIPTOR_SIZE)
  61           return DescriptorTooLarge;
  62
  63         /* Allocate enough memory for the entire config descriptor */
  64         ConfigDescriptorData = alloca(ConfigDescriptorSize);
  65
  66         /* Retrieve the entire configuration descriptor into the allocated buffer */
  67         USB_GetDeviceConfigDescriptor(1, &ConfigDescriptorSize, ConfigDescriptorData);
  68
  69         /* Validate returned data - ensure first entry is a configuration header descriptor */
  70         if (DESCRIPTOR_TYPE(ConfigDescriptorData) != DTYPE_Configuration)
  71           return InvalidConfigDataReturned;
  72
  73         /* Get the HID interface from the configuration descriptor */
  74         if (USB_GetNextDescriptorComp(&ConfigDescriptorSize, &ConfigDescriptorData,
  75                                       DComp_NextHIDInterface) != DESCRIPTOR_SEARCH_COMP_Found)
  76         {
  77                 /* Descriptor not found, error out */
  78                 return NoHIDInterfaceFound;
  79         }
  80
  81         while (FoundEndpoints != ((1 << HID_DATA_IN_PIPE) | (1 << HID_DATA_OUT_PIPE)))
  82         {
  83                 /* Get the next HID interface's data endpoint descriptor */
  84                 if (USB_GetNextDescriptorComp(&ConfigDescriptorSize, &ConfigDescriptorData,
  85                                               DComp_NextInterfaceHIDDataEndpoint) != DESCRIPTOR_SEARCH_COMP_Found)
  86                 {
  87                         /* Not all HID devices have an OUT endpoint - if we've reached the end of the HID descriptor
  88                          * but only found the mandatory IN endpoint, it's safe to continue with the device enumeration */
  89                         if (FoundEndpoints == (1 << HID_DATA_IN_PIPE))
  90                           break;
  91
  92                         /* Descriptor not found, error out */
  93                         return NoEndpointFound;
  94                 }
  95
  96                 /* Retrieve the endpoint address from the endpoint descriptor */
  97                 USB_Descriptor_Endpoint_t* EndpointData = DESCRIPTOR_PCAST(ConfigDescriptorData, USB_Descriptor_Endpoint_t);
  98
  99                 /* If the endpoint is a IN type endpoint */
 100                 if (EndpointData->EndpointAddress & ENDPOINT_DESCRIPTOR_DIR_IN)
 101                 {
 102                         /* Configure the HID data IN pipe */
 103                         Pipe_ConfigurePipe(HID_DATA_IN_PIPE, EP_TYPE_INTERRUPT, PIPE_TOKEN_IN,
 104                                                            EndpointData->EndpointAddress, EndpointData->EndpointSize, PIPE_BANK_SINGLE);
 105
 106                         FoundEndpoints |= (1 << HID_DATA_IN_PIPE);
 107                 }
 108                 else
 109                 {
 110                         /* Configure the HID data OUT pipe */
 111                         Pipe_ConfigurePipe(HID_DATA_OUT_PIPE, EP_TYPE_INTERRUPT, PIPE_TOKEN_OUT,
 112                                                            EndpointData->EndpointAddress, EndpointData->EndpointSize, PIPE_BANK_SINGLE);
 113
 114                         FoundEndpoints |= (1 << HID_DATA_OUT_PIPE);
 115                 }
 116         }
 117
 118         /* Valid data found, return success */
 119         return SuccessfulConfigRead;
 120 }
 121
 122 /** Descriptor comparator function. This comparator function is can be called while processing an attached USB device's
 123  *  configuration descriptor, to search for a specific sub descriptor. It can also be used to abort the configuration
 124  *  descriptor processing if an incompatible descriptor configuration is found.
 125  *
 126  *  This comparator searches for the next Interface descriptor of the correct HID Class value.
 127  *
 128  *  \return A value from the DSEARCH_Return_ErrorCodes_t enum
 129  */
 130 uint8_t DComp_NextHIDInterface(void* CurrentDescriptor)
 131 {
 132         /* Determine if the current descriptor is an interface descriptor */
 133         if (DESCRIPTOR_TYPE(CurrentDescriptor) == DTYPE_Interface)
 134         {
 135                 /* Check the HID descriptor class, break out if correct class/protocol interface found */
 136                 if (DESCRIPTOR_CAST(CurrentDescriptor, USB_Descriptor_Interface_t).Class == HID_CLASS)
 137                 {
 138                         /* Indicate that the descriptor being searched for has been found */
 139                         return DESCRIPTOR_SEARCH_Found;
 140                 }
 141         }
 142
 143         /* Current descriptor does not match what this comparator is looking for */
 144         return DESCRIPTOR_SEARCH_NotFound;
 145 }
 146
 147 /** Descriptor comparator function. This comparator function is can be called while processing an attached USB device's
 148  *  configuration descriptor, to search for a specific sub descriptor. It can also be used to abort the configuration
 149  *  descriptor processing if an incompatible descriptor configuration is found.
 150  *
 151  *  This comparator searches for the next Endpoint descriptor inside the current interface descriptor,
 152  *  aborting the search if another interface descriptor is found before the required endpoint.
 153  *
 154  *  \return A value from the DSEARCH_Return_ErrorCodes_t enum
 155  */
 156 uint8_t DComp_NextInterfaceHIDDataEndpoint(void* CurrentDescriptor)
 157 {
 158         /* Determine the type of the current descriptor */
 159         if (DESCRIPTOR_TYPE(CurrentDescriptor) == DTYPE_Endpoint)
 160         {
 161                 /* Indicate that the descriptor being searched for has been found */
 162                 return DESCRIPTOR_SEARCH_Found;
 163         }
 164         else if (DESCRIPTOR_TYPE(CurrentDescriptor) == DTYPE_Interface)
 165         {
 166                 /* Indicate that the search has failed prematurely and should be aborted */
 167                 return DESCRIPTOR_SEARCH_Fail;
 168         }
 169
 170         /* Current descriptor does not match what this comparator is looking for */
 171         return DESCRIPTOR_SEARCH_NotFound;
 172 }