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+/*
+ LUFA Library
+ Copyright (C) Dean Camera, 2017.
+
+ dean [at] fourwalledcubicle [dot] com
+ www.lufa-lib.org
+*/
+
+/*
+ Copyright 2017 Dean Camera (dean [at] fourwalledcubicle [dot] com)
+
+ Permission to use, copy, modify, distribute, and sell this
+ software and its documentation for any purpose is hereby granted
+ without fee, provided that the above copyright notice appear in
+ all copies and that both that the copyright notice and this
+ permission notice and warranty disclaimer appear in supporting
+ documentation, and that the name of the author not be used in
+ advertising or publicity pertaining to distribution of the
+ software without specific, written prior permission.
+
+ The author disclaims all warranties with regard to this
+ software, including all implied warranties of merchantability
+ and fitness. In no event shall the author be liable for any
+ special, indirect or consequential damages or any damages
+ whatsoever resulting from loss of use, data or profits, whether
+ in an action of contract, negligence or other tortious action,
+ arising out of or in connection with the use or performance of
+ this software.
+*/
+
+/** \file
+ *
+ * Virtualized FAT12 filesystem implementation, to perform self-programming
+ * in response to read and write requests to the virtual filesystem by the
+ * host PC.
+ */
+
+#define INCLUDE_FROM_VIRTUAL_FAT_C
+#include "VirtualFAT.h"
+
+/** FAT filesystem boot sector block, must be the first sector on the physical
+ * disk so that the host can identify the presence of a FAT filesystem. This
+ * block is truncated; normally a large bootstrap section is located near the
+ * end of the block for booting purposes however as this is not meant to be a
+ * bootable disk it is omitted for space reasons.
+ *
+ * \note When returning the boot block to the host, the magic signature 0xAA55
+ * must be added to the very end of the block to identify it as a boot
+ * block.
+ */
+static const FATBootBlock_t BootBlock =
+ {
+ .Bootstrap = {0xEB, 0x3C, 0x90},
+ .Description = "mkdosfs",
+ .SectorSize = SECTOR_SIZE_BYTES,
+ .SectorsPerCluster = SECTOR_PER_CLUSTER,
+ .ReservedSectors = 1,
+ .FATCopies = 2,
+ .RootDirectoryEntries = (SECTOR_SIZE_BYTES / sizeof(FATDirectoryEntry_t)),
+ .TotalSectors16 = LUN_MEDIA_BLOCKS,
+ .MediaDescriptor = 0xF8,
+ .SectorsPerFAT = 1,
+ .SectorsPerTrack = (LUN_MEDIA_BLOCKS % 64),
+ .Heads = (LUN_MEDIA_BLOCKS / 64),
+ .HiddenSectors = 0,
+ .TotalSectors32 = 0,
+ .PhysicalDriveNum = 0,
+ .ExtendedBootRecordSig = 0x29,
+ .VolumeSerialNumber = 0x12345678,
+ .VolumeLabel = "LUFA BOOT ",
+ .FilesystemIdentifier = "FAT12 ",
+ };
+
+/** FAT 8.3 style directory entry, for the virtual FLASH contents file. */
+static FATDirectoryEntry_t FirmwareFileEntries[] =
+ {
+ /* Root volume label entry; disk label is contained in the Filename and
+ * Extension fields (concatenated) with a special attribute flag - other
+ * fields are ignored. Should be the same as the label in the boot block.
+ */
+ [DISK_FILE_ENTRY_VolumeID] =
+ {
+ .MSDOS_Directory =
+ {
+ .Name = "LUFA BOOT ",
+ .Attributes = FAT_FLAG_VOLUME_NAME,
+ .Reserved = {0},
+ .CreationTime = 0,
+ .CreationDate = 0,
+ .StartingCluster = 0,
+ .Reserved2 = 0,
+ }
+ },
+
+ /* VFAT Long File Name entry for the virtual firmware file; required to
+ * prevent corruption from systems that are unable to detect the device
+ * as being a legacy MSDOS style FAT12 volume. */
+ [DISK_FILE_ENTRY_FLASH_LFN] =
+ {
+ .VFAT_LongFileName =
+ {
+ .Ordinal = 1 | FAT_ORDINAL_LAST_ENTRY,
+ .Attribute = FAT_FLAG_LONG_FILE_NAME,
+ .Reserved1 = 0,
+ .Reserved2 = 0,
+
+ .Checksum = FAT_CHECKSUM('F','L','A','S','H',' ',' ',' ','B','I','N'),
+
+ .Unicode1 = 'F',
+ .Unicode2 = 'L',
+ .Unicode3 = 'A',
+ .Unicode4 = 'S',
+ .Unicode5 = 'H',
+ .Unicode6 = '.',
+ .Unicode7 = 'B',
+ .Unicode8 = 'I',
+ .Unicode9 = 'N',
+ .Unicode10 = 0,
+ .Unicode11 = 0,
+ .Unicode12 = 0,
+ .Unicode13 = 0,
+ }
+ },
+
+ /* MSDOS file entry for the virtual Firmware image. */
+ [DISK_FILE_ENTRY_FLASH_MSDOS] =
+ {
+ .MSDOS_File =
+ {
+ .Filename = "FLASH ",
+ .Extension = "BIN",
+ .Attributes = 0,
+ .Reserved = {0},
+ .CreationTime = FAT_TIME(1, 1, 0),
+ .CreationDate = FAT_DATE(14, 2, 1989),
+ .StartingCluster = 2,
+ .FileSizeBytes = FLASH_FILE_SIZE_BYTES,
+ }
+ },
+
+ [DISK_FILE_ENTRY_EEPROM_LFN] =
+ {
+ .VFAT_LongFileName =
+ {
+ .Ordinal = 1 | FAT_ORDINAL_LAST_ENTRY,
+ .Attribute = FAT_FLAG_LONG_FILE_NAME,
+ .Reserved1 = 0,
+ .Reserved2 = 0,
+
+ .Checksum = FAT_CHECKSUM('E','E','P','R','O','M',' ',' ','B','I','N'),
+
+ .Unicode1 = 'E',
+ .Unicode2 = 'E',
+ .Unicode3 = 'P',
+ .Unicode4 = 'R',
+ .Unicode5 = 'O',
+ .Unicode6 = 'M',
+ .Unicode7 = '.',
+ .Unicode8 = 'B',
+ .Unicode9 = 'I',
+ .Unicode10 = 'N',
+ .Unicode11 = 0,
+ .Unicode12 = 0,
+ .Unicode13 = 0,
+ }
+ },
+
+ [DISK_FILE_ENTRY_EEPROM_MSDOS] =
+ {
+ .MSDOS_File =
+ {
+ .Filename = "EEPROM ",
+ .Extension = "BIN",
+ .Attributes = 0,
+ .Reserved = {0},
+ .CreationTime = FAT_TIME(1, 1, 0),
+ .CreationDate = FAT_DATE(14, 2, 1989),
+ .StartingCluster = 2 + FILE_CLUSTERS(FLASH_FILE_SIZE_BYTES),
+ .FileSizeBytes = EEPROM_FILE_SIZE_BYTES,
+ }
+ },
+ };
+
+/** Starting cluster of the virtual FLASH.BIN file on disk, tracked so that the
+ * offset from the start of the data sector can be determined. On Windows
+ * systems files are usually replaced using the original file's disk clusters,
+ * while Linux appears to overwrite with an offset which must be compensated for.
+ */
+static const uint16_t* FLASHFileStartCluster = &FirmwareFileEntries[DISK_FILE_ENTRY_FLASH_MSDOS].MSDOS_File.StartingCluster;
+
+/** Starting cluster of the virtual EEPROM.BIN file on disk, tracked so that the
+ * offset from the start of the data sector can be determined. On Windows
+ * systems files are usually replaced using the original file's disk clusters,
+ * while Linux appears to overwrite with an offset which must be compensated for.
+ */
+static const uint16_t* EEPROMFileStartCluster = &FirmwareFileEntries[DISK_FILE_ENTRY_EEPROM_MSDOS].MSDOS_File.StartingCluster;
+
+/** Reads a byte of EEPROM out from the EEPROM memory space.
+ *
+ * \note This function is required as the avr-libc EEPROM functions do not cope
+ * with linker relaxations, and a jump longer than 4K of FLASH on the
+ * larger USB AVRs will break the linker. This function is marked as
+ * never inlinable and placed into the normal text segment so that the
+ * call to the EEPROM function will be short even if the AUX boot section
+ * is used.
+ *
+ * \param[in] Address Address of the EEPROM location to read from
+ *
+ * \return Read byte of EEPROM data.
+ */
+static uint8_t ReadEEPROMByte(const uint8_t* const Address)
+{
+ return eeprom_read_byte(Address);
+}
+
+/** Writes a byte of EEPROM out to the EEPROM memory space.
+ *
+ * \note This function is required as the avr-libc EEPROM functions do not cope
+ * with linker relaxations, and a jump longer than 4K of FLASH on the
+ * larger USB AVRs will break the linker. This function is marked as
+ * never inlinable and placed into the normal text segment so that the
+ * call to the EEPROM function will be short even if the AUX boot section
+ * is used.
+ *
+ * \param[in] Address Address of the EEPROM location to write to
+ * \param[in] Data New data to write to the EEPROM location
+ */
+static void WriteEEPROMByte(uint8_t* const Address,
+ const uint8_t Data)
+{
+ eeprom_update_byte(Address, Data);
+}
+
+/** Updates a FAT12 cluster entry in the FAT file table with the specified next
+ * chain index. If the cluster is the last in the file chain, the magic value
+ * \c 0xFFF should be used.
+ *
+ * \note FAT data cluster indexes are offset by 2, so that cluster 2 is the
+ * first file data cluster on the disk. See the FAT specification.
+ *
+ * \param[out] FATTable Pointer to the FAT12 allocation table
+ * \param[in] Index Index of the cluster entry to update
+ * \param[in] ChainEntry Next cluster index in the file chain
+ */
+static void UpdateFAT12ClusterEntry(uint8_t* const FATTable,
+ const uint16_t Index,
+ const uint16_t ChainEntry)
+{
+ /* Calculate the starting offset of the cluster entry in the FAT12 table */
+ uint8_t FATOffset = (Index + (Index >> 1));
+ bool UpperNibble = ((Index & 1) != 0);
+
+ /* Check if the start of the entry is at an upper nibble of the byte, fill
+ * out FAT12 entry as required */
+ if (UpperNibble)
+ {
+ FATTable[FATOffset] = (FATTable[FATOffset] & 0x0F) | ((ChainEntry & 0x0F) << 4);
+ FATTable[FATOffset + 1] = (ChainEntry >> 4);
+ }
+ else
+ {
+ FATTable[FATOffset] = ChainEntry;
+ FATTable[FATOffset + 1] = (FATTable[FATOffset] & 0xF0) | (ChainEntry >> 8);
+ }
+}
+
+/** Updates a FAT12 cluster chain in the FAT file table with a linear chain of
+ * the specified length.
+ *
+ * \note FAT data cluster indexes are offset by 2, so that cluster 2 is the
+ * first file data cluster on the disk. See the FAT specification.
+ *
+ * \param[out] FATTable Pointer to the FAT12 allocation table
+ * \param[in] Index Index of the start of the cluster chain to update
+ * \param[in] ChainLength Length of the chain to write, in clusters
+ */
+static void UpdateFAT12ClusterChain(uint8_t* const FATTable,
+ const uint16_t Index,
+ const uint8_t ChainLength)
+{
+ for (uint8_t i = 0; i < ChainLength; i++)
+ {
+ uint16_t CurrentCluster = Index + i;
+ uint16_t NextCluster = CurrentCluster + 1;
+
+ /* Mark last cluster as end of file */
+ if (i == (ChainLength - 1))
+ NextCluster = 0xFFF;
+
+ UpdateFAT12ClusterEntry(FATTable, CurrentCluster, NextCluster);
+ }
+}
+
+/** Reads or writes a block of data from/to the physical device FLASH using a
+ * block buffer stored in RAM, if the requested block is within the virtual
+ * firmware file's sector ranges in the emulated FAT file system.
+ *
+ * \param[in] BlockNumber Physical disk block to read from/write to
+ * \param[in,out] BlockBuffer Pointer to the start of the block buffer in RAM
+ * \param[in] Read If \c true, the requested block is read, if
+ * \c false, the requested block is written
+ */
+static void ReadWriteFLASHFileBlock(const uint16_t BlockNumber,
+ uint8_t* BlockBuffer,
+ const bool Read)
+{
+ uint16_t FileStartBlock = DISK_BLOCK_DataStartBlock + (*FLASHFileStartCluster - 2) * SECTOR_PER_CLUSTER;
+ uint16_t FileEndBlock = FileStartBlock + (FILE_SECTORS(FLASH_FILE_SIZE_BYTES) - 1);
+
+ /* Range check the write request - abort if requested block is not within the
+ * virtual firmware file sector range */
+ if (!((BlockNumber >= FileStartBlock) && (BlockNumber <= FileEndBlock)))
+ return;
+
+ #if (FLASHEND > 0xFFFF)
+ uint32_t FlashAddress = (uint32_t)(BlockNumber - FileStartBlock) * SECTOR_SIZE_BYTES;
+ #else
+ uint16_t FlashAddress = (uint16_t)(BlockNumber - FileStartBlock) * SECTOR_SIZE_BYTES;
+ #endif
+
+ if (Read)
+ {
+ /* Read out the mapped block of data from the device's FLASH */
+ for (uint16_t i = 0; i < SECTOR_SIZE_BYTES; i++)
+ {
+ #if (FLASHEND > 0xFFFF)
+ BlockBuffer[i] = pgm_read_byte_far(FlashAddress++);
+ #else
+ BlockBuffer[i] = pgm_read_byte(FlashAddress++);
+ #endif
+ }
+ }
+ else
+ {
+ /* Write out the mapped block of data to the device's FLASH */
+ for (uint16_t i = 0; i < SECTOR_SIZE_BYTES; i += 2)
+ {
+ if ((FlashAddress % SPM_PAGESIZE) == 0)
+ {
+ /* Erase the given FLASH page, ready to be programmed */
+ BootloaderAPI_ErasePage(FlashAddress);
+ }
+
+ /* Write the next data word to the FLASH page */
+ BootloaderAPI_FillWord(FlashAddress, (BlockBuffer[i + 1] << 8) | BlockBuffer[i]);
+ FlashAddress += 2;
+
+ if ((FlashAddress % SPM_PAGESIZE) == 0)
+ {
+ /* Write the filled FLASH page to memory */
+ BootloaderAPI_WritePage(FlashAddress - SPM_PAGESIZE);
+ }
+ }
+ }
+}
+
+/** Reads or writes a block of data from/to the physical device EEPROM using a
+ * block buffer stored in RAM, if the requested block is within the virtual
+ * firmware file's sector ranges in the emulated FAT file system.
+ *
+ * \param[in] BlockNumber Physical disk block to read from/write to
+ * \param[in,out] BlockBuffer Pointer to the start of the block buffer in RAM
+ * \param[in] Read If \c true, the requested block is read, if
+ * \c false, the requested block is written
+ */
+static void ReadWriteEEPROMFileBlock(const uint16_t BlockNumber,
+ uint8_t* BlockBuffer,
+ const bool Read)
+{
+ uint16_t FileStartBlock = DISK_BLOCK_DataStartBlock + (*EEPROMFileStartCluster - 2) * SECTOR_PER_CLUSTER;
+ uint16_t FileEndBlock = FileStartBlock + (FILE_SECTORS(EEPROM_FILE_SIZE_BYTES) - 1);
+
+ /* Range check the write request - abort if requested block is not within the
+ * virtual firmware file sector range */
+ if (!((BlockNumber >= FileStartBlock) && (BlockNumber <= FileEndBlock)))
+ return;
+
+ uint16_t EEPROMAddress = (uint16_t)(BlockNumber - FileStartBlock) * SECTOR_SIZE_BYTES;
+
+ if (Read)
+ {
+ /* Read out the mapped block of data from the device's EEPROM */
+ for (uint16_t i = 0; i < SECTOR_SIZE_BYTES; i++)
+ BlockBuffer[i] = ReadEEPROMByte((uint8_t*)EEPROMAddress++);
+ }
+ else
+ {
+ /* Write out the mapped block of data to the device's EEPROM */
+ for (uint16_t i = 0; i < SECTOR_SIZE_BYTES; i++)
+ WriteEEPROMByte((uint8_t*)EEPROMAddress++, BlockBuffer[i]);
+ }
+}
+
+/** Writes a block of data to the virtual FAT filesystem, from the USB Mass
+ * Storage interface.
+ *
+ * \param[in] BlockNumber Index of the block to write.
+ */
+void VirtualFAT_WriteBlock(const uint16_t BlockNumber)
+{
+ uint8_t BlockBuffer[SECTOR_SIZE_BYTES];
+
+ /* Buffer the entire block to be written from the host */
+ Endpoint_Read_Stream_LE(BlockBuffer, sizeof(BlockBuffer), NULL);
+ Endpoint_ClearOUT();
+
+ switch (BlockNumber)
+ {
+ case DISK_BLOCK_BootBlock:
+ case DISK_BLOCK_FATBlock1:
+ case DISK_BLOCK_FATBlock2:
+ /* Ignore writes to the boot and FAT blocks */
+
+ break;
+
+ case DISK_BLOCK_RootFilesBlock:
+ /* Copy over the updated directory entries */
+ memcpy(FirmwareFileEntries, BlockBuffer, sizeof(FirmwareFileEntries));
+
+ break;
+
+ default:
+ ReadWriteFLASHFileBlock(BlockNumber, BlockBuffer, false);
+ ReadWriteEEPROMFileBlock(BlockNumber, BlockBuffer, false);
+
+ break;
+ }
+}
+
+/** Reads a block of data from the virtual FAT filesystem, and sends it to the
+ * host via the USB Mass Storage interface.
+ *
+ * \param[in] BlockNumber Index of the block to read.
+ */
+void VirtualFAT_ReadBlock(const uint16_t BlockNumber)
+{
+ uint8_t BlockBuffer[SECTOR_SIZE_BYTES];
+ memset(BlockBuffer, 0x00, sizeof(BlockBuffer));
+
+ switch (BlockNumber)
+ {
+ case DISK_BLOCK_BootBlock:
+ memcpy(BlockBuffer, &BootBlock, sizeof(FATBootBlock_t));
+
+ /* Add the magic signature to the end of the block */
+ BlockBuffer[SECTOR_SIZE_BYTES - 2] = 0x55;
+ BlockBuffer[SECTOR_SIZE_BYTES - 1] = 0xAA;
+
+ break;
+
+ case DISK_BLOCK_FATBlock1:
+ case DISK_BLOCK_FATBlock2:
+ /* Cluster 0: Media type/Reserved */
+ UpdateFAT12ClusterEntry(BlockBuffer, 0, 0xF00 | BootBlock.MediaDescriptor);
+
+ /* Cluster 1: Reserved */
+ UpdateFAT12ClusterEntry(BlockBuffer, 1, 0xFFF);
+
+ /* Cluster 2 onwards: Cluster chain of FLASH.BIN */
+ UpdateFAT12ClusterChain(BlockBuffer, *FLASHFileStartCluster, FILE_CLUSTERS(FLASH_FILE_SIZE_BYTES));
+
+ /* Cluster 2+n onwards: Cluster chain of EEPROM.BIN */
+ UpdateFAT12ClusterChain(BlockBuffer, *EEPROMFileStartCluster, FILE_CLUSTERS(EEPROM_FILE_SIZE_BYTES));
+
+ break;
+
+ case DISK_BLOCK_RootFilesBlock:
+ memcpy(BlockBuffer, FirmwareFileEntries, sizeof(FirmwareFileEntries));
+
+ break;
+
+ default:
+ ReadWriteFLASHFileBlock(BlockNumber, BlockBuffer, true);
+ ReadWriteEEPROMFileBlock(BlockNumber, BlockBuffer, true);
+
+ break;
+ }
+
+ /* Write the entire read block Buffer to the host */
+ Endpoint_Write_Stream_LE(BlockBuffer, sizeof(BlockBuffer), NULL);
+ Endpoint_ClearIN();
+}