src/drivers/block/ramdisk.c

   1 /*
   2  * Copyright (C) 2007 Michael Brown <mbrown@fensystems.co.uk>.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License as
   6  * published by the Free Software Foundation; either version 2 of the
   7  * License, or any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  17  */
  18
  19 #include <gpxe/blockdev.h>
  20 #include <gpxe/ramdisk.h>
  21
  22 /**
  23  * @file
  24  *
  25  * RAM disks
  26  *
  27  */
  28
  29 static inline __attribute__ (( always_inline )) struct ramdisk *
  30 block_to_ramdisk ( struct block_device *blockdev ) {
  31         return container_of ( blockdev, struct ramdisk, blockdev );
  32 }
  33
  34 /**
  35  * Read block
  36  *
  37  * @v blockdev          Block device
  38  * @v block             Block number
  39  * @v count             Block count
  40  * @v buffer            Data buffer
  41  * @ret rc              Return status code
  42  */
  43 static int ramdisk_read ( struct block_device *blockdev, uint64_t block,
  44                           unsigned long count, userptr_t buffer ) {
  45         struct ramdisk *ramdisk = block_to_ramdisk ( blockdev );
  46         unsigned long offset = ( block * blockdev->blksize );
  47         unsigned long length = ( count * blockdev->blksize );
  48
  49         DBGC ( ramdisk, "RAMDISK %p reading [%lx,%lx)\n",
  50                ramdisk, offset, length );
  51
  52         memcpy_user ( buffer, 0, ramdisk->data, offset, length );
  53         return 0;
  54 }
  55
  56 /**
  57  * Write block
  58  *
  59  * @v blockdev          Block device
  60  * @v block             Block number
  61  * @v count             Block count
  62  * @v buffer            Data buffer
  63  * @ret rc              Return status code
  64  */
  65 static int ramdisk_write ( struct block_device *blockdev, uint64_t block,
  66                            unsigned long count, userptr_t buffer ) {
  67         struct ramdisk *ramdisk = block_to_ramdisk ( blockdev );
  68         unsigned long offset = ( block * blockdev->blksize );
  69         unsigned long length = ( count * blockdev->blksize );
  70
  71         DBGC ( ramdisk, "RAMDISK %p writing [%lx,%lx)\n",
  72                ramdisk, offset, length );
  73
  74         memcpy_user ( ramdisk->data, offset, buffer, 0, length );
  75         return 0;
  76 }
  77
  78 int init_ramdisk ( struct ramdisk *ramdisk, userptr_t data, size_t len,
  79                    unsigned int blksize ) {
  80
  81         if ( ! blksize )
  82                 blksize = 512;
  83
  84         ramdisk->data = data;
  85         ramdisk->blockdev.read = ramdisk_read;
  86         ramdisk->blockdev.write = ramdisk_write;
  87         ramdisk->blockdev.blksize = blksize;
  88         ramdisk->blockdev.blocks = ( len / blksize );
  89
  90         return 0;
  91 }