gpxe/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 FILE_LICENCE ( GPL2_OR_LATER );
  20
  21 #include <gpxe/blockdev.h>
  22 #include <gpxe/ramdisk.h>
  23
  24 /**
  25  * @file
  26  *
  27  * RAM disks
  28  *
  29  */
  30
  31 static inline __attribute__ (( always_inline )) struct ramdisk *
  32 block_to_ramdisk ( struct block_device *blockdev ) {
  33         return container_of ( blockdev, struct ramdisk, blockdev );
  34 }
  35
  36 /**
  37  * Read block
  38  *
  39  * @v blockdev          Block device
  40  * @v block             Block number
  41  * @v count             Block count
  42  * @v buffer            Data buffer
  43  * @ret rc              Return status code
  44  */
  45 static int ramdisk_read ( struct block_device *blockdev, uint64_t block,
  46                           unsigned long count, userptr_t buffer ) {
  47         struct ramdisk *ramdisk = block_to_ramdisk ( blockdev );
  48         unsigned long offset = ( block * blockdev->blksize );
  49         unsigned long length = ( count * blockdev->blksize );
  50
  51         DBGC ( ramdisk, "RAMDISK %p reading [%lx,%lx)\n",
  52                ramdisk, offset, length );
  53
  54         memcpy_user ( buffer, 0, ramdisk->data, offset, length );
  55         return 0;
  56 }
  57
  58 /**
  59  * Write block
  60  *
  61  * @v blockdev          Block device
  62  * @v block             Block number
  63  * @v count             Block count
  64  * @v buffer            Data buffer
  65  * @ret rc              Return status code
  66  */
  67 static int ramdisk_write ( struct block_device *blockdev, uint64_t block,
  68                            unsigned long count, userptr_t buffer ) {
  69         struct ramdisk *ramdisk = block_to_ramdisk ( blockdev );
  70         unsigned long offset = ( block * blockdev->blksize );
  71         unsigned long length = ( count * blockdev->blksize );
  72
  73         DBGC ( ramdisk, "RAMDISK %p writing [%lx,%lx)\n",
  74                ramdisk, offset, length );
  75
  76         memcpy_user ( ramdisk->data, offset, buffer, 0, length );
  77         return 0;
  78 }
  79
  80 static struct block_device_operations ramdisk_operations = {
  81         .read   = ramdisk_read,
  82         .write  = ramdisk_write
  83 };
  84
  85 int init_ramdisk ( struct ramdisk *ramdisk, userptr_t data, size_t len,
  86                    unsigned int blksize ) {
  87
  88         if ( ! blksize )
  89                 blksize = 512;
  90
  91         ramdisk->data = data;
  92         ramdisk->blockdev.op = &ramdisk_operations;
  93         ramdisk->blockdev.blksize = blksize;
  94         ramdisk->blockdev.blocks = ( len / blksize );
  95
  96         return 0;
  97 }