ref: 75c92428225428c8fde2d015f010e608a0b12f1d
dir: /os/boot/pc/dma.c/
#include "u.h"
#include "lib.h"
#include "mem.h"
#include "dat.h"
#include "fns.h"
typedef struct DMAport DMAport;
typedef struct DMA DMA;
typedef struct DMAxfer DMAxfer;
enum
{
/*
* the byte registers for DMA0 are all one byte apart
*/
Dma0= 0x00,
Dma0status= Dma0+0x8, /* status port */
Dma0reset= Dma0+0xD, /* reset port */
/*
* the byte registers for DMA1 are all two bytes apart (why?)
*/
Dma1= 0xC0,
Dma1status= Dma1+2*0x8, /* status port */
Dma1reset= Dma1+2*0xD, /* reset port */
};
/*
* state of a dma transfer
*/
struct DMAxfer
{
ulong bpa; /* bounce buffer physical address */
void* bva; /* bounce buffer virtual address */
void* va; /* virtual address destination/src */
long len; /* bytes to be transferred */
int isread;
};
/*
* the dma controllers. the first half of this structure specifies
* the I/O ports used by the DMA controllers.
*/
struct DMAport
{
uchar addr[4]; /* current address (4 channels) */
uchar count[4]; /* current count (4 channels) */
uchar page[4]; /* page registers (4 channels) */
uchar cmd; /* command status register */
uchar req; /* request registers */
uchar sbm; /* single bit mask register */
uchar mode; /* mode register */
uchar cbp; /* clear byte pointer */
uchar mc; /* master clear */
uchar cmask; /* clear mask register */
uchar wam; /* write all mask register bit */
};
struct DMA
{
DMAport;
int shift;
Lock;
DMAxfer x[4];
};
DMA dma[2] = {
{ 0x00, 0x02, 0x04, 0x06,
0x01, 0x03, 0x05, 0x07,
0x87, 0x83, 0x81, 0x82,
0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
0 },
{ 0xc0, 0xc4, 0xc8, 0xcc,
0xc2, 0xc6, 0xca, 0xce,
0x8f, 0x8b, 0x89, 0x8a,
0xd0, 0xd2, 0xd4, 0xd6, 0xd8, 0xda, 0xdc, 0xde,
1 },
};
/*
* DMA must be in the first 16MB. This gets called early by the
* initialisation routines of any devices which require DMA to ensure
* the allocated bounce buffers are below the 16MB limit.
*/
void
dmainit(int chan)
{
DMA *dp;
DMAxfer *xp;
ulong v;
static int once;
if(once == 0){
// if(ioalloc(0x00, 0x10, 0, "dma") < 0
// || ioalloc(0x80, 0x10, 0, "dma") < 0
// || ioalloc(0xd0, 0x10, 0, "dma") < 0)
// panic("dmainit");
outb(dma[0].mc, 0);
outb(dma[1].mc, 0);
outb(dma[0].cmask, 0);
outb(dma[1].cmask, 0);
outb(dma[1].mode, 0xC0);
once = 1;
}
dp = &dma[(chan>>2)&1];
chan = chan & 3;
xp = &dp->x[chan];
if(xp->bva != nil)
return;
v = (ulong)xalloc(BY2PG+BY2PG);
if(v == 0 || PADDR(v) >= 16*MB){
print("dmainit: chan %d: 0x%luX out of range\n", chan, v);
xfree((void*)v);
v = 0;
}
xp->bva = (void*)ROUND(v, BY2PG);
xp->bpa = PADDR(xp->bva);
xp->len = 0;
xp->isread = 0;
}
/*
* setup a dma transfer. if the destination is not in kernel
* memory, allocate a page for the transfer.
*
* we assume BIOS has set up the command register before we
* are booted.
*
* return the updated transfer length (we can't transfer across 64k
* boundaries)
*/
long
dmasetup(int chan, void *va, long len, int isread)
{
DMA *dp;
ulong pa;
uchar mode;
DMAxfer *xp;
dp = &dma[(chan>>2)&1];
chan = chan & 3;
xp = &dp->x[chan];
/*
* if this isn't kernel memory or crossing 64k boundary or above 16 meg
* use the allocated low memory page.
*/
pa = PADDR(va);
if((((ulong)va)&0xF0000000) != KZERO
|| (pa&0xFFFF0000) != ((pa+len)&0xFFFF0000)
|| pa > 16*MB) {
if(xp->bva == nil)
return -1;
if(len > BY2PG)
len = BY2PG;
if(!isread)
memmove(xp->bva, va, len);
xp->va = va;
xp->len = len;
xp->isread = isread;
pa = xp->bpa;
}
else
xp->len = 0;
/*
* this setup must be atomic
*/
ilock(dp);
mode = (isread ? 0x44 : 0x48) | chan;
outb(dp->mode, mode); /* single mode dma (give CPU a chance at mem) */
outb(dp->page[chan], pa>>16);
outb(dp->cbp, 0); /* set count & address to their first byte */
outb(dp->addr[chan], pa>>dp->shift); /* set address */
outb(dp->addr[chan], pa>>(8+dp->shift));
outb(dp->count[chan], (len>>dp->shift)-1); /* set count */
outb(dp->count[chan], ((len>>dp->shift)-1)>>8);
outb(dp->sbm, chan); /* enable the channel */
iunlock(dp);
return len;
}
int
dmadone(int chan)
{
DMA *dp;
dp = &dma[(chan>>2)&1];
chan = chan & 3;
return inb(dp->cmd) & (1<<chan);
}
/*
* this must be called after a dma has been completed.
*
* if a page has been allocated for the dma,
* copy the data into the actual destination
* and free the page.
*/
void
dmaend(int chan)
{
DMA *dp;
DMAxfer *xp;
dp = &dma[(chan>>2)&1];
chan = chan & 3;
/*
* disable the channel
*/
ilock(dp);
outb(dp->sbm, 4|chan);
iunlock(dp);
xp = &dp->x[chan];
if(xp->len == 0 || !xp->isread)
return;
/*
* copy out of temporary page
*/
memmove(xp->va, xp->bva, xp->len);
xp->len = 0;
}
/*
int
dmacount(int chan)
{
int retval;
DMA *dp;
dp = &dma[(chan>>2)&1];
outb(dp->cbp, 0);
retval = inb(dp->count[chan]);
retval |= inb(dp->count[chan]) << 8;
return((retval<<dp->shift)+1);
}
*/