sys/arch/i386/stand/lib/isadma.c

   1 /*      $NetBSD: isadma.c,v 1.2 2008/12/14 17:03:43 christos Exp $      */
   2
   3 /* from: NetBSD:dev/isa/isadma.c */
   4
   5 #include <sys/types.h>
   6 #include <machine/pio.h>
   7
   8 #include <lib/libsa/stand.h>
   9
  10 #include "isadmavar.h"
  11
  12 #define IO_DMA1         0x000           /* 8237A DMA Controller #1 */
  13 #define IO_DMA2         0x0C0           /* 8237A DMA Controller #2 */
  14 #define DMA37MD_CASCADE 0xc0    /* cascade mode */
  15 #define DMA1_SMSK       (IO_DMA1 + 1*10)        /* single mask register */
  16 #define DMA1_MODE       (IO_DMA1 + 1*11)        /* mode register */
  17 #define DMA2_SMSK       (IO_DMA2 + 2*10)        /* single mask register */
  18 #define DMA2_MODE       (IO_DMA2 + 2*11)        /* mode register */
  19
  20 /*
  21  * isa_dmacascade(): program 8237 DMA controller channel to accept
  22  * external dma control by a board.
  23  */
  24 void
  25 isa_dmacascade(int chan)
  26 {
  27
  28 #ifdef ISADMA_DEBUG
  29         if (chan < 0 || chan > 7)
  30                 panic("isa_dmacascade: impossible request");
  31 #endif
  32
  33         /* set dma channel mode, and set dma channel mode */
  34         if ((chan & 4) == 0) {
  35                 outb(DMA1_MODE, chan | DMA37MD_CASCADE);
  36                 outb(DMA1_SMSK, chan);
  37         } else {
  38                 chan &= 3;
  39
  40                 outb(DMA2_MODE, chan | DMA37MD_CASCADE);
  41                 outb(DMA2_SMSK, chan);
  42         }
  43 }