libc/x86/dma.c

   1 /*
   2  *  ZeX/OS
   3  *  Copyright (C) 2007  Tomas 'ZeXx86' Jedrzejek (zexx86@gmail.com)
   4  *
   5  *  This program is free software: you can redistribute it and/or modify
   6  *  it under the terms of the GNU General Public License as published by
   7  *  the Free Software Foundation, either version 3 of the License, or
   8  *  (at your option) any later version.
   9  *
  10  *  This program is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License
  16  *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17  */
  18
  19
  20 #include "x86.h"
  21 #include "dma.h"
  22
  23 /* Just helps in making things look cleaner.  :) */
  24 typedef unsigned char   uchar;
  25 typedef unsigned int    uint;
  26
  27 /* Defines for accessing the upper and lower byte of an integer. */
  28 #define LOW_BYTE(x)         (x & 0x00FF)
  29 #define HI_BYTE(x)          ((x & 0xFF00) >> 8)
  30
  31 /* Quick-access registers and ports for each DMA channel. */
  32 uchar MaskReg[8]   = { 0x0A, 0x0A, 0x0A, 0x0A, 0xD4, 0xD4, 0xD4, 0xD4 };
  33 uchar ModeReg[8]   = { 0x0B, 0x0B, 0x0B, 0x0B, 0xD6, 0xD6, 0xD6, 0xD6 };
  34 uchar ClearReg[8]  = { 0x0C, 0x0C, 0x0C, 0x0C, 0xD8, 0xD8, 0xD8, 0xD8 };
  35
  36 uchar PagePort[8]  = { 0x87, 0x83, 0x81, 0x82, 0x8F, 0x8B, 0x89, 0x8A };
  37 uchar AddrPort[8]  = { 0x00, 0x02, 0x04, 0x06, 0xC0, 0xC4, 0xC8, 0xCC };
  38 uchar CountPort[8] = { 0x01, 0x03, 0x05, 0x07, 0xC2, 0xC6, 0xCA, 0xCE };
  39
  40 void _dma_xfer(uchar DMA_channel, unsigned char page, unsigned int offset, unsigned int length, uchar mode);
  41
  42 void dma_xfer(uchar channel, unsigned long address, unsigned int length, unsigned char read)
  43 {
  44         unsigned char page=0, mode=0;
  45         unsigned int offset = 0;
  46
  47         if(read)
  48                 mode = 0x48 + channel;
  49         else
  50                 mode = 0x44 + channel;
  51
  52         page = address >> 16;
  53         offset = address & 0xFFFF;
  54         length--;
  55
  56         _dma_xfer(channel, page, offset, length, mode);
  57 }
  58
  59
  60 void _dma_xfer(uchar DMA_channel, unsigned char page, unsigned int offset, unsigned int length, uchar mode)
  61 {
  62     /* Don't let anyone else mess up what we're doing. */
  63     asm("cli");
  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     outportb(MaskReg[DMA_channel], 0x04 | DMA_channel);
  68
  69     /* Clear any data transfers that are currently executing. */
  70     outportb(ClearReg[DMA_channel], 0x00);
  71
  72     /* Send the specified mode to the DMA. */
  73     outportb(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     outportb(AddrPort[DMA_channel], LOW_BYTE(offset));
  78     outportb(AddrPort[DMA_channel], HI_BYTE(offset));
  79
  80     /* Send the physical page that the data lies on. */
  81     outportb(PagePort[DMA_channel], page);
  82
  83     /* Send the length of the data.  Again, low byte first. */
  84     outportb(CountPort[DMA_channel], LOW_BYTE(length));
  85     outportb(CountPort[DMA_channel], HI_BYTE(length));
  86
  87     /* Ok, we're done.  Enable the DMA channel (clear the mask). */
  88     outportb(MaskReg[DMA_channel], DMA_channel);
  89
  90     /* Re-enable interrupts before we leave. */
  91     asm("sti");
  92 }