date and time created 90/11/08 20:00:03 by bill

[unix-history] / usr / src / sys / i386 / isa / isa.c

/*
* code to manage AT bus
* @(#)isa.c    1.1 (Berkeley) %G%
*/

#include "param.h"
#include "systm.h"
#include "conf.h"
#include "file.h"
#include "dir.h"
#include "user.h"
#include "buf.h"
#include "vm.h"
#include "uio.h"
#include "machine/pte.h"

/* stuff needed for virtual to physical calculations */
extern char Sysbase;
static unsigned long sbase = (unsigned long) &Sysbase;

struct buf *dma_bounce[8];
#define MAXDMASZ 512

/* XXX temporary */
kernel_space(x)
unsigned long x;
{
       if ((x >= sbase) & (x < sbase + 0x800000)) return 1;
       else return 0;
}


/****************************************************************************/
/*                                 at_dma                                   */
/* set up DMA read/write operation and virtual address addr for nbytes      */
/****************************************************************************/
at_dma(read,addr,nbytes, chan)
int read;
unsigned long addr;
int nbytes;
{
       unsigned long phys;
       int s,raw;
       caddr_t bounce;

       if (kernel_space(addr)) raw = 0;
       else raw = 1;

       if(raw) {
               if (dma_bounce[chan] == 0)
                       dma_bounce[chan] = geteblk(MAXDMASZ);
               bounce = dma_bounce[chan]->b_un.b_addr;
       }

       /* copy bounce buffer on write */
       if (raw && !read) bcopy(addr,bounce,nbytes);

       /* Set read/write bytes */
       if (read) {
               outb(0xC,0x46); outb(0xB,0x46);
       } else {
               outb(0xC,0x4A); outb(0xB,0x4A);
       }
       /* Send start address */
       if (raw) phys = (unsigned long) bounce;
       else phys = addr;
       /* translate to physical */
       phys = phys - sbase;
       outb(0x4,phys & 0xFF);
       outb(0x4,(phys>>8) & 0xFF);
       outb(0x81,(phys>>16) & 0xFF);
       /* Send count */
       nbytes--;
       outb(0x5,nbytes & 0xFF);
       outb(0x5,(nbytes>>8) & 0xFF);
       /* set channel 2 */
       outb(0x0A,chan);
}