kernel/lib/x86/dma.c

   1 /*
   2  *  ZeX/OS
   3  *  Copyright (C) 2007  Tomas 'ZeXx86' Jedrzejek (zexx86@zexos.org)
   4  *  Copyright (C) 2008  Tomas 'ZeXx86' Jedrzejek (zexx86@zexos.org)
   5  *
   6  *  This program is free software: you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License as published by
   8  *  the Free Software Foundation, either version 3 of the License, or
   9  *  (at your option) any later version.
  10  *
  11  *  This program is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20
  21 #include <system.h>
  22 #include <arch/io.h>
  23 #include <dma.h>
  24 #include <build.h>
  25
  26 #ifdef ARCH_i386
  27
  28 /* Defines for accessing the upper and lower byte of an integer. */
  29 #define LOW_BYTE(x)         (x & 0x00FF)
  30 #define HI_BYTE(x)          ((x & 0xFF00) >> 8)
  31
  32 /* Quick-access registers and ports for each DMA channel. */
  33 unsigned char MaskReg[8]   = { 0x0A, 0x0A, 0x0A, 0x0A, 0xD4, 0xD4, 0xD4, 0xD4 };
  34 unsigned char ModeReg[8]   = { 0x0B, 0x0B, 0x0B, 0x0B, 0xD6, 0xD6, 0xD6, 0xD6 };
  35 unsigned char ClearReg[8]  = { 0x0C, 0x0C, 0x0C, 0x0C, 0xD8, 0xD8, 0xD8, 0xD8 };
  36
  37 unsigned char PagePort[8]  = { 0x87, 0x83, 0x81, 0x82, 0x8F, 0x8B, 0x89, 0x8A };
  38 unsigned char AddrPort[8]  = { 0x00, 0x02, 0x04, 0x06, 0xC0, 0xC4, 0xC8, 0xCC };
  39 unsigned char CountPort[8] = { 0x01, 0x03, 0x05, 0x07, 0xC2, 0xC6, 0xCA, 0xCE };
  40
  41 void _dma_xfer (unsigned char DMA_channel, unsigned char page, unsigned int offset, unsigned int length, unsigned char mode);
  42
  43 void dma_xfer (unsigned char channel, unsigned long address, unsigned int length, unsigned char read)
  44 {
  45         unsigned char page=0, mode=0;
  46         unsigned int offset = 0;
  47
  48         if(read)
  49                 mode = 0x48 + channel;
  50         else
  51                 mode = 0x44 + channel;
  52
  53         page = address >> 16;
  54         offset = address & 0xFFFF;
  55         length--;
  56
  57         _dma_xfer (channel, page, offset, length, mode);
  58 }
  59
  60 void _dma_xfer (unsigned char DMA_channel, unsigned char page, unsigned int offset, unsigned int length, unsigned char mode)
  61 {
  62         /* Don't let anyone else mess up what we're doing. */
  63         int_disable ();
  64
  65         /* Set up the DMA channel so we can use it.  This tells the DMA */
  66         /* that we're going to be using this channel.  (It's masked) */
  67         outb (MaskReg[DMA_channel], 0x04 | DMA_channel);
  68
  69         /* Clear any data transfers that are currently executing. */
  70         outb (ClearReg[DMA_channel], 0x00);
  71
  72         /* Send the specified mode to the DMA. */
  73         outb (ModeReg[DMA_channel], mode);
  74
  75         /* Send the offset address.  The first byte is the low base offset, the */
  76         /* second byte is the high offset. */
  77         outb (AddrPort[DMA_channel], LOW_BYTE(offset));
  78         outb (AddrPort[DMA_channel], HI_BYTE(offset));
  79
  80         /* Send the physical page that the data lies on. */
  81         outb (PagePort[DMA_channel], page);
  82
  83         /* Send the length of the data.  Again, low byte first. */
  84         outb (CountPort[DMA_channel], LOW_BYTE(length));
  85         outb (CountPort[DMA_channel], HI_BYTE(length));
  86
  87         /* Ok, we're done.  Enable the DMA channel (clear the mask). */
  88         outb (MaskReg[DMA_channel], DMA_channel);
  89
  90         /* Re-enable interrupts before we leave. */
  91         int_enable ();
  92 }
  93 #endif
  94