Demos/Host/LowLevel/KeyboardHostWithParser/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 and HID descriptor.
  45  *
  46  *  \return An error code from the KeyboardHostWithParser_GetConfigDescriptorDataCodes_t enum.
  47  */
  48 uint8_t ProcessConfigurationDescriptor(void)
  49 {
  50         uint8_t* ConfigDescriptorData;
  51         uint16_t ConfigDescriptorSize;
  52
  53         /* Get Configuration Descriptor size from the device */
  54         if (USB_GetDeviceConfigDescriptor(1, &ConfigDescriptorSize, NULL) != HOST_SENDCONTROL_Successful)
  55           return ControlError;
  56
  57         /* Ensure that the Configuration Descriptor isn't too large */
  58         if (ConfigDescriptorSize > MAX_CONFIG_DESCRIPTOR_SIZE)
  59           return DescriptorTooLarge;
  60
  61         /* Allocate enough memory for the entire config descriptor */
  62         ConfigDescriptorData = alloca(ConfigDescriptorSize);
  63
  64         /* Retrieve the entire configuration descriptor into the allocated buffer */
  65         USB_GetDeviceConfigDescriptor(1, &ConfigDescriptorSize, ConfigDescriptorData);
  66
  67         /* Validate returned data - ensure first entry is a configuration header descriptor */
  68         if (DESCRIPTOR_TYPE(ConfigDescriptorData) != DTYPE_Configuration)
  69           return InvalidConfigDataReturned;
  70
  71         /* Get the keyboard interface from the configuration descriptor */
  72         if (USB_GetNextDescriptorComp(&ConfigDescriptorSize, &ConfigDescriptorData,
  73                                       DComp_NextKeyboardInterface) != DESCRIPTOR_SEARCH_COMP_Found)
  74         {
  75                 /* Descriptor not found, error out */
  76                 return NoHIDInterfaceFound;
  77         }
  78
  79         /* Get the keyboard interface's HID descriptor */
  80         if (USB_GetNextDescriptorComp(&ConfigDescriptorSize, &ConfigDescriptorData,
  81                                       DComp_NextHID) != DESCRIPTOR_SEARCH_COMP_Found)
  82         {
  83                 /* Descriptor not found, error out */
  84                 return NoHIDDescriptorFound;
  85         }
  86
  87         /* Save the HID report size for later use */
  88         HIDReportSize = DESCRIPTOR_CAST(ConfigDescriptorData, USB_Descriptor_HID_t).HIDReportLength;
  89
  90         /* Get the keyboard interface's data endpoint descriptor */
  91         if (USB_GetNextDescriptorComp(&ConfigDescriptorSize, &ConfigDescriptorData,
  92                                       DComp_NextInterfaceKeyboardDataEndpoint) != DESCRIPTOR_SEARCH_COMP_Found)
  93         {
  94                 /* Descriptor not found, error out */
  95                 return NoEndpointFound;
  96         }
  97
  98         /* Retrieve the endpoint address from the endpoint descriptor */
  99         USB_Descriptor_Endpoint_t* EndpointData = DESCRIPTOR_PCAST(ConfigDescriptorData, USB_Descriptor_Endpoint_t);
 100
 101         /* Configure the keyboard data pipe */
 102         Pipe_ConfigurePipe(KEYBOARD_DATAPIPE, EP_TYPE_INTERRUPT, PIPE_TOKEN_IN,
 103                            EndpointData->EndpointAddress, EndpointData->EndpointSize, PIPE_BANK_SINGLE);
 104
 105         /* Valid data found, return success */
 106         return SuccessfulConfigRead;
 107 }
 108
 109 /** Descriptor comparator function. This comparator function is can be called while processing an attached USB device's
 110  *  configuration descriptor, to search for a specific sub descriptor. It can also be used to abort the configuration
 111  *  descriptor processing if an incompatible descriptor configuration is found.
 112  *
 113  *  This comparator searches for the next Interface descriptor of the correct Keyboard HID Class and Protocol values.
 114  *
 115  *  \return A value from the DSEARCH_Return_ErrorCodes_t enum
 116  */
 117 uint8_t DComp_NextKeyboardInterface(void* CurrentDescriptor)
 118 {
 119         if (DESCRIPTOR_TYPE(CurrentDescriptor) == DTYPE_Interface)
 120         {
 121                 /* Check the HID descriptor class and protocol, break out if correct class/protocol interface found */
 122                 if ((DESCRIPTOR_CAST(CurrentDescriptor, USB_Descriptor_Interface_t).Class    == KEYBOARD_CLASS) &&
 123                     (DESCRIPTOR_CAST(CurrentDescriptor, USB_Descriptor_Interface_t).Protocol == KEYBOARD_PROTOCOL))
 124                 {
 125                         return DESCRIPTOR_SEARCH_Found;
 126                 }
 127         }
 128
 129         return DESCRIPTOR_SEARCH_NotFound;
 130 }
 131
 132 /** Descriptor comparator function. This comparator function is can be called while processing an attached USB device's
 133  *  configuration descriptor, to search for a specific sub descriptor. It can also be used to abort the configuration
 134  *  descriptor processing if an incompatible descriptor configuration is found.
 135  *
 136  *  This comparator searches for the next IN Endpoint descriptor inside the current interface descriptor,
 137  *  aborting the search if another interface descriptor is found before the required endpoint.
 138  *
 139  *  \return A value from the DSEARCH_Return_ErrorCodes_t enum
 140  */
 141 uint8_t DComp_NextInterfaceKeyboardDataEndpoint(void* CurrentDescriptor)
 142 {
 143         if (DESCRIPTOR_TYPE(CurrentDescriptor) == DTYPE_Endpoint)
 144         {
 145                 if (DESCRIPTOR_CAST(CurrentDescriptor, USB_Descriptor_Endpoint_t).EndpointAddress & ENDPOINT_DESCRIPTOR_DIR_IN)
 146                   return DESCRIPTOR_SEARCH_Found;
 147         }
 148         else if (DESCRIPTOR_TYPE(CurrentDescriptor) == DTYPE_Interface)
 149         {
 150                 return DESCRIPTOR_SEARCH_Fail;
 151         }
 152
 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 HID descriptor within the current HID interface descriptor.
 161  *
 162  *  \return A value from the DSEARCH_Return_ErrorCodes_t enum
 163  */
 164 uint8_t DComp_NextHID(void* CurrentDescriptor)
 165 {
 166         if (DESCRIPTOR_TYPE(CurrentDescriptor) == DTYPE_HID)
 167           return DESCRIPTOR_SEARCH_Found;
 168         else
 169           return DESCRIPTOR_SEARCH_NotFound;
 170 }