source: trunk/kernel/vfs/fatfs.c @ 191

/*
 * fatfs.c - FATFS file system API implementation.
 *
 * Author    Mohamed Lamine Karaoui (2014,2015)
 *           Alain Greiner (2016,2017)
 *
 * Copyright (c) UPMC Sorbonne Universites
 *
 * This file is part of ALMOS-MKH.
 *
 * ALMOS-MKH is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2.0 of the License.
 *
 * ALMOS-MKH is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with ALMOS-MKH; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 */


#include <hal_types.h>
#include <hal_special.h>
#include <printk.h>
#include <kmem.h>
#include <ppm.h>
#include <vfs.h>
#include <rpc.h>
#include <mapper.h>
#include <cluster.h>
#include <dev_ioc.h>
#include <fatfs.h>


//////////////////////////////////////////////////////////////////////////////////////////
//          Extern  variables         
//////////////////////////////////////////////////////////////////////////////////////////

extern vfs_ctx_t          fs_context[FS_TYPES_NR];   // allocated in vfs.c file

extern remote_barrier_t   global_barrier;            // allocated in kernel_init.c
 
//////////////////////////////////////////////////////////////////////////////////////////
//              FATFS private functions 
//////////////////////////////////////////////////////////////////////////////////////////

//////////////////////////////////////////////////////////////////////////////////////////
// This function returns the LBA of the first sector of a FAT cluster.
// This function can be called by any thread running in any cluster.
//////////////////////////////////////////////////////////////////////////////////////////
// @ ctx          :     pointer on FATFS context.
// @ cluster  : cluster index in FATFS.
// @ return the lba value.
//////////////////////////////////////////////////////////////////////////////////////////
static inline uint32_t fatfs_lba_from_cluster( fatfs_ctx_t * ctx,
                                               uint32_t      cluster )
{
    return (ctx->cluster_begin_lba + ((cluster - 2) << 3));
}

/////////////////////////////////////////////
error_t fatfs_get_cluster( mapper_t * mapper,
                           uint32_t   first_cluster,
                           uint32_t   searched_page,
                           uint32_t * cluster )
{
    page_t   * current_page_desc;      // pointer on current page descriptor
    uint32_t * current_page_buffer;    // pointer on current page (array of uint32_t)
    uint32_t   current_page_index;     // index of current page in mapper 
    uint32_t   current_page_offset;    // offset of slot in current page
    uint32_t   page_count_in_file;     // index of page in file (index in linked list)
    uint32_t   current_cluster;        // content of current FAT slot

    // compute number of FAT slots per PPM page
    uint32_t slots_per_page = CONFIG_PPM_PAGE_SIZE >> 2;

    // initialize loop variable
    current_page_index  = first_cluster / slots_per_page;
    current_page_offset = first_cluster % slots_per_page;
    page_count_in_file  = 0;

    // scan FAT (i.e. traverse FAT linked list)
    while( page_count_in_file <= searched_page )
    {
        // get pointer on current page descriptor
        current_page_desc = mapper_get_page( mapper , current_page_index );

        if( current_page_desc == NULL ) return EIO;

        // get pointer on buffer for current page
        current_page_buffer = (uint32_t *)ppm_page2vaddr( current_page_desc );

        // get FAT slot content 
        current_cluster = current_page_buffer[current_page_offset];

        // update loop variables
        current_page_index  = current_cluster / slots_per_page;
        current_page_offset = current_cluster % slots_per_page;
        page_count_in_file++;
    }
    
    // return success
    *cluster = current_cluster;
    return 0;

}  // end fatfs_get_cluster()

///////////////////////////////////////////////////////////////////////////////////////
// This static function return an integer record value (one, two, or four bytes) 
// from a memory buffer, taking into account endianness.
///////////////////////////////////////////////////////////////////////////////////////
// @ offset        : first byte of record in buffer.
// @ size          : record length in bytes (1/2/4).
// @ buffer        : pointer on buffer base.
// @ little endian : the most significant byte has the highest address when true.
// @ return the integer value in a 32 bits word.
///////////////////////////////////////////////////////////////////////////////////////
static uint32_t get_record_from_buffer( uint32_t    offset,
                                        uint32_t    size,
                                        uint8_t   * buffer,
                                        uint32_t    little_endian )
{
    uint32_t n;
    uint32_t res  = 0;

    if ( little_endian)
    {
        for( n = size ; n > 0 ; n-- ) res = (res<<8) | buffer[offset+n-1];
    }
    else
    {
        for( n = 0 ; n < size ; n++ ) res = (res<<8) | buffer[offset+n];
    }
    return res;

}  // end get_record_from_buffer()



////////////////////////////////////////////////////////////////////////////////////////
// This function returns the FATFS cluster index of a page identified by its page
// index in the file, using the FAT mapper. It scans the FAT mapper, starting from the
// FATFS cluster index allocated to the first page of the file, until it reaches the 
// searched page. The FAT mapper is automatically updated in case of miss. 
// This function can be called by any thread running in any cluster, as it uses the
// RPC_FATFS_GET_CLUSTER to access the remote FAT mapper if required.
// We use a RPC to scan the FAT because the RPC_FIFO will avoid contention
// in the cluster containing the FAT mapper, and the RPC latency is not critical
// compared to the device access latency.
////////////////////////////////////////////////////////////////////////////////////////
// @ ctx               : pointer on local FATFS context.
// @ first_cluster : first cluster allocated to a file in FATFS.
// @ page_index    : index of searched page in file (one page occupies one cluster).
// @ cluster_index : [out] pointer on buffer for FATFS cluster index.
// @ return 0 if success / return EIO if a FAT cluster miss cannot be solved.
////////////////////////////////////////////////////////////////////////////////////////
static error_t fatfs_cluster_from_index( fatfs_ctx_t * ctx,
                                         uint32_t      first_cluster,
                                         uint32_t      page_index,
                                         uint32_t    * cluster_index )
{
    uint32_t searched_cluster;   // searched FATFS cluster index
    error_t  error;

    // get extended pointer on FAT mapper
    xptr_t fat_mapper_xp = ctx->fat_mapper_xp;

    // get cluster cxy and local pointer on FAT mapper
    cxy_t      fat_mapper_cxy = GET_CXY( fat_mapper_xp );
    mapper_t * fat_mapper_ptr = (mapper_t *)GET_PTR( fat_mapper_xp );

    if( fat_mapper_cxy == local_cxy )    // FAT mapper is local
    {
        error = fatfs_get_cluster( fat_mapper_ptr,
                                   first_cluster,
                                   page_index,
                                   &searched_cluster );
    }
    else                                 // FAT mapper is remote
    {
        rpc_fatfs_get_cluster_client( fat_mapper_cxy,
                                      fat_mapper_ptr,
                                      first_cluster,
                                      page_index,
                                      &searched_cluster,
                                      &error );
    }
    
    if( error )
    {
        printk("\n[ERROR] in %s : cannot access FAT\n", __FUNCTION__ );
        return error;
    }

    // return success
    *cluster_index = searched_cluster;
    return 0;

}  // end fatfs_cluster_from_index()




///////////////////////////////////////////////////////////////////////////////////////
// Generic API : the following functions are called by the kernel
//               and must be defined by all supported file systems.
///////////////////////////////////////////////////////////////////////////////////////

///////////////////////////////
fatfs_ctx_t * fatfs_ctx_alloc()
{
    kmem_req_t    req;
        req.type    = KMEM_FATFS_CTX;
        req.size    = sizeof(fatfs_ctx_t);
    req.flags   = AF_KERNEL | AF_ZERO;

        return (fatfs_ctx_t *)kmem_alloc( &req );
}

//////////////////////////////////////////////
void fatfs_ctx_init( fatfs_ctx_t * fatfs_ctx )
{
    error_t       error;
    kmem_req_t    req;
    uint8_t     * buffer;

    fatfs_dmsg("\n[INFO] %s : enters at cycle %d\n", 
               __FUNCTION__ , hal_get_cycles() );

    // allocate memory for FATFS context
        req.type    = KMEM_FATFS_CTX;
        req.size    = sizeof(fatfs_ctx_t);
    req.flags   = AF_KERNEL | AF_ZERO;

        fatfs_ctx = (fatfs_ctx_t *)kmem_alloc( &req );

    nolock_assert( (fatfs_ctx != NULL) , __FUNCTION__ ,
                   "cannot allocate memory for FATFS context\n" );

    // allocate a 512 bytes buffer to store the boot record
        req.type    = KMEM_512_BYTES;
    req.flags   = AF_KERNEL | AF_ZERO;
        buffer      = (uint8_t *)kmem_alloc( &req );

    nolock_assert( (buffer != NULL) , __FUNCTION__ ,
                   "cannot allocate memory for 512 bytes buffer\n" );
     
    // load the boot record from device
    // using a synchronous access to IOC device  
    error = dev_ioc_sync_read( buffer , 0 , 1 );

    nolock_assert( (error == 0) , __FUNCTION__ ,
                   "cannot access boot record\n" );

#if CONFIG_FATFS_DEBUG
    uint32_t   line;
    uint32_t   byte = 0;
    printk("\n*** boot record at cycle %d ***\n", hal_get_cycles() );
    for ( line = 0 ; line < 32 ; line++ )
    {
        printk(" %X | %x %x %x %x %x %x %x %x %x %x %x %x %x %x %x %x |\n",
               byte,
               buffer[byte+ 0],buffer[byte+ 1],buffer[byte+ 2],buffer[byte+ 3],
               buffer[byte+ 4],buffer[byte+ 5],buffer[byte+ 6],buffer[byte+ 7],
               buffer[byte+ 8],buffer[byte+ 9],buffer[byte+10],buffer[byte+11],
               buffer[byte+12],buffer[byte+13],buffer[byte+14],buffer[byte+15] );

         byte += 16;
    }
#endif

    // check sector size from boot record
    uint32_t sector_size = get_record_from_buffer( BPB_BYTSPERSEC , buffer , 1 );

    nolock_assert( (sector_size == 512) , __FUNCTION__ ,
                   "sector size must be 512 bytes\n" );

    // check cluster size from boot record
    uint32_t nb_sectors = get_record_from_buffer( BPB_SECPERCLUS , buffer , 1 );

    nolock_assert( (nb_sectors == 8) , __FUNCTION__ ,
                   "cluster size must be 8 sectors\n" );

    // check number of FAT copies from boot record
    uint32_t nb_fats = get_record_from_buffer( BPB_NUMFATS , buffer , 1 );

    nolock_assert( (nb_fats == 1) , __FUNCTION__ ,
                   "number of FAT copies must be 1\n" );

    // get & check number of sectors in FAT from boot record
    uint32_t fat_sectors = get_record_from_buffer( BPB_FAT32_FATSZ32 , buffer , 1 );

    nolock_assert( ((fat_sectors & 0xF) == 0) , __FUNCTION__ ,
                   "FAT not multiple of 16 sectors\n");

    // get and check root cluster from boot record
    uint32_t root_cluster = get_record_from_buffer( BPB_FAT32_ROOTCLUS , buffer , 1 );

    nolock_assert( (root_cluster == 2) , __FUNCTION__ ,
                   "root cluster index must be  2\n");

    // get FAT lba from boot record
    uint32_t fat_lba = get_record_from_buffer( BPB_RSVDSECCNT , buffer , 1 );

    // release the 512 bytes buffer
    req.type = KMEM_512_BYTES;
    req.ptr  = buffer;
    kmem_free( &req );

    // allocate a mapper for the FAT itself
    mapper_t * fat_mapper = mapper_create();

    assert( (fat_mapper != NULL) , __FUNCTION__ , "no memory for FAT mapper" );

    // initialize the FATFS context
    fatfs_ctx->fat_begin_lba         = fat_lba;
    fatfs_ctx->fat_sectors_count     = fat_sectors; 
    fatfs_ctx->bytes_per_sector      = sector_size;
    fatfs_ctx->sectors_per_cluster   = nb_sectors;
    fatfs_ctx->cluster_begin_lba     = fat_lba + fat_sectors;
    fatfs_ctx->root_dir_cluster      = 2;
    fatfs_ctx->last_allocated_sector = 0;    // TODO ???
    fatfs_ctx->last_allocated_index  = 0;    // TODO ???
    fatfs_ctx->fat_mapper_xp         = XPTR( local_cxy , fat_mapper );

    fatfs_dmsg("\n*** FAT context ***\n" 
               "- fat_sectors     = %d\n"
               "- sector size     = %d\n"
               "- cluster size    = %d\n"
               "- fat_first_lba   = %d\n"
               "- data_first_lba  = %d\n"
               "- mapper          = %l\n",
               fatfs_ctx->fat_sectors_count,
               fatfs_ctx->bytes_per_sector,
               fatfs_ctx->bytes_per_cluster,
               fatfs_ctx->fat_begin_lba,
               fatfs_ctx->cluster_begin_lba,
               fatfs_ctx->fat_mapper_xp );

}  // end fatfs_ctx_init()

/////////////////////////////////////////////////
void fatfs_ctx_destroy( fatfs_ctx_t * fatfs_ctx )
{
    kmem_req_t    req;
    req.type = KMEM_FATFS_CTX;
    req.ptr  = fatfs_ctx;
    kmem_free( &req );
}

////////////////////////////////////////////////
static error_t fatfs_access_page( page_t * page,
                                  bool_t   is_read )
{
    // get memory buffer base address
    uint8_t * buffer = (uint8_t *)ppm_page2vaddr( page );
 
    // get pointer on source mapper and page index from page descriptor
    mapper_t * mapper      = page->mapper;
    uint32_t   page_index  = page->index;

    // get VFS inode pointer from mapper
    vfs_inode_t * vfs_inode = mapper->inode;

    // get first cluster index from VFS inode
    uint32_t  first_cluster = (uint32_t)(intptr_t)vfs_inode->extend;

    // get FATFS context pointer from VFS context
    fatfs_ctx_t * fatfs_ctx = (fatfs_ctx_t *)fs_context[FS_TYPE_FATFS].extend;

    // get number of sectors 
    uint32_t count = fatfs_ctx->sectors_per_cluster;

    // compute FATFS_cluster index for the accessed page
    uint32_t cluster = 0;
    error_t  error = fatfs_cluster_from_index( fatfs_ctx,
                                               first_cluster,
                                               page_index,
                                               &cluster );
    if( error ) return EIO;

    // get lba from cluster
    uint32_t lba = fatfs_lba_from_cluster( fatfs_ctx , cluster );

    // access device
    if( is_read ) error = dev_ioc_read ( buffer , lba , count );
    else          error = dev_ioc_write( buffer , lba , count );     

    if( error )
    {
        printk("\n[ERROR] in %s : cannot access IOC device\n", __FUNCTION__ );
        return error;
    } 

    // successful access 
    return 0;
}

////////////////////////////////////////////////
error_t fatfs_write_page( struct page_s * page )
{
    bool_t is_read = false;
    return fatfs_access_page( page , is_read );
}

///////////////////////////////////////////////
error_t fatfs_read_page( struct page_s * page )
{
    bool_t is_read = true;
    return fatfs_access_page( page , is_read );
}