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Add isa_dmastatus() for reading the current ISA DMA counter for a

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given channel.

Submitted by:	luigi@labinfo.iet.unipi.it (Luigi Rizzo)
This commit is contained in:
msmith 1997-07-24 05:27:40 +00:00
parent 526dc5f515
commit a27c19ecbf
3 changed files with 164 additions and 3 deletions
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82
sys/amd64/isa/isa.c
View File

@ -34,7 +34,7 @@
* SUCH DAMAGE.
*
* from: @(#)isa.c 7.2 (Berkeley) 5/13/91
* $Id: isa.c,v 1.94 1997/07/09 17:58:16 ache Exp $
* $Id: isa.c,v 1.95 1997/07/20 14:10:03 bde Exp $
*/
/*
@ -869,6 +869,86 @@ isa_dmarangecheck(caddr_t va, u_int length, int chan) {
return (0);
}
/*
* Query the progress of a transfer on a DMA channel.
*
* To avoid having to interrupt a transfer in progress, we sample
* each of the high and low databytes twice, and apply the following
* logic to determine the correct count.
*
* Reads are performed with interrupts disabled, thus it is to be
* expected that the time between reads is very small. At most
* one rollover in the low count byte can be expected within the
* four reads that are performed.
*
* There are three gaps in which a rollover can occur :
*
* - read low1
* gap1
* - read high1
* gap2
* - read low2
* gap3
* - read high2
*
* If a rollover occurs in gap1 or gap2, the low2 value will be
* greater than the low1 value. In this case, low2 and high2 are a
* corresponding pair.
*
* In any other case, low1 and high1 can be considered to be correct.
*
* The function returns the number of bytes remaining in the transfer,
* or -1 if the channel requested is not active.
*
*/
int
isa_dmastatus(int chan)
{
u_long cnt = 0;
int ffport, waport, s;
u_long low, high, low2, high2;
/* channel active? */
if (dma_inuse & (1 << chan) == 0) {
printf("isa_dmastatus: channel %d not active\n", chan);
return(-1);
}
/* still busy? */
if (dma_busy & (1 << chan) == 0) {
return(0);
}
if (chan < 4) { /* low DMA controller */
ffport = DMA1_FFC;
waport = DMA1_CHN(chan) + 1;
} else { /* high DMA controller */
ffport = DMA2_FFC;
waport = DMA2_CHN(chan - 4) + 2;
}
s = splhigh(); /* no interrupts Mr Jones! */
outb(ffport, 0); /* clear register LSB flipflop */
low = inb(waport);
high = inb(waport);
outb(ffport, 0); /* clear again (paranoia?) */
low2 = inb(waport);
high2 = inb(waport);
splx(s);
/* now decide if a wrap has tried to skew our results */
if (low >= low2) {
cnt = low + (high << 8) + 1;
} else {
cnt = low2 + (high2 << 8) + 1;
}
cnt = (cnt + 1) & 0xffff;
if (chan >= 4) /* high channels move words */
cnt *= 2;
return(cnt);
}
/*
* Find the highest priority enabled display device. Since we can't
* distinguish display devices from ttys, depend on display devices

82
sys/i386/isa/isa.c
View File

@ -34,7 +34,7 @@
* SUCH DAMAGE.
*
* from: @(#)isa.c 7.2 (Berkeley) 5/13/91
* $Id: isa.c,v 1.94 1997/07/09 17:58:16 ache Exp $
* $Id: isa.c,v 1.95 1997/07/20 14:10:03 bde Exp $
*/
/*
@ -869,6 +869,86 @@ isa_dmarangecheck(caddr_t va, u_int length, int chan) {
return (0);
}
/*
* Query the progress of a transfer on a DMA channel.
*
* To avoid having to interrupt a transfer in progress, we sample
* each of the high and low databytes twice, and apply the following
* logic to determine the correct count.
*
* Reads are performed with interrupts disabled, thus it is to be
* expected that the time between reads is very small. At most
* one rollover in the low count byte can be expected within the
* four reads that are performed.
*
* There are three gaps in which a rollover can occur :
*
* - read low1
* gap1
* - read high1
* gap2
* - read low2
* gap3
* - read high2
*
* If a rollover occurs in gap1 or gap2, the low2 value will be
* greater than the low1 value. In this case, low2 and high2 are a
* corresponding pair.
*
* In any other case, low1 and high1 can be considered to be correct.
*
* The function returns the number of bytes remaining in the transfer,
* or -1 if the channel requested is not active.
*
*/
int
isa_dmastatus(int chan)
{
u_long cnt = 0;
int ffport, waport, s;
u_long low, high, low2, high2;
/* channel active? */
if (dma_inuse & (1 << chan) == 0) {
printf("isa_dmastatus: channel %d not active\n", chan);
return(-1);
}
/* still busy? */
if (dma_busy & (1 << chan) == 0) {
return(0);
}
if (chan < 4) { /* low DMA controller */
ffport = DMA1_FFC;
waport = DMA1_CHN(chan) + 1;
} else { /* high DMA controller */
ffport = DMA2_FFC;
waport = DMA2_CHN(chan - 4) + 2;
}
s = splhigh(); /* no interrupts Mr Jones! */
outb(ffport, 0); /* clear register LSB flipflop */
low = inb(waport);
high = inb(waport);
outb(ffport, 0); /* clear again (paranoia?) */
low2 = inb(waport);
high2 = inb(waport);
splx(s);
/* now decide if a wrap has tried to skew our results */
if (low >= low2) {
cnt = low + (high << 8) + 1;
} else {
cnt = low2 + (high2 << 8) + 1;
}
cnt = (cnt + 1) & 0xffff;
if (chan >= 4) /* high channels move words */
cnt *= 2;
return(cnt);
}
/*
* Find the highest priority enabled display device. Since we can't
* distinguish display devices from ttys, depend on display devices

3
sys/i386/isa/isa_device.h
View File

@ -31,7 +31,7 @@
* SUCH DAMAGE.
*
* from: @(#)isa_device.h 7.1 (Berkeley) 5/9/91
* $Id: isa_device.h,v 1.42 1997/06/02 08:19:05 dfr Exp $
* $Id: isa_device.h,v 1.43 1997/07/20 12:34:15 bde Exp $
*/
#ifndef _I386_ISA_ISA_DEVICE_H_
@ -117,6 +117,7 @@ void isa_dmainit __P((int chan, u_int bouncebufsize));
void isa_dmastart __P((int flags, caddr_t addr, u_int nbytes, int chan));
int isa_dma_acquire __P((int chan));
void isa_dma_release __P((int chan));
void isa_dmastatus __P((int chan));
void reconfig_isadev __P((struct isa_device *isdp, u_int *mp));
#endif /* KERNEL */