void dma_start(dma_buffer * buffer, unsigned long count, unsigned char mode)
{
/* Disable interrupts */
int old_ints = disable();
dma_disable(buffer->channel);
dma_set_mode(buffer->channel, mode);
dma_clear_ff(buffer->channel);
dma_set_addr(buffer->channel, buffer->physical);
dma_clear_ff(buffer->channel);
dma_set_count(buffer->channel, count);
dma_enable(buffer->channel);
/* Re-enable interrupts */
if (old_ints)
enable();
}
static boolean __wss_detect()
{
/* First find the port number */
if (!wss.port) {
static unsigned int wss_ports[] =
{ 0x32c, 0x530, 0x604, 0xE80, 0xF40 };
int i;
for (i = 0; i < 5; i++) {
wss.port = wss_ports[i];
if (__wss_ping())
break;
}
if (i < 0) {
wss.port = 0;
return FALSE;
}
}
/* Now disable output */
wss_output(FALSE);
/* Detect the DMA channel */
if (!wss.dma) {
static int __dma[] = { 0, 1, 3 };
int i;
/* Enable playback IRQ */
__wss_regbit_set(WSSR_PIN_CTRL, WSSM_IRQ_ENABLE);
__wss_outreg(WSSR_IRQ_STATUS, WSSM_PLAYBACK_IRQ);
/* Start a short DMA transfer and check if DMA count is zero */
for (i = 0; i < 3; i++) {
unsigned int timer, status, freq = 44100;
wss.dma = __dma[i];
dma_disable(wss.dma);
dma_set_mode(wss.dma, DMA_MODE_WRITE);
dma_clear_ff(wss.dma);
dma_set_count(wss.dma, 10);
dma_enable(wss.dma);
/* Clear IRQ status */
outportb(WSS_STATUS, 0);
__wss_setformat(__wss_getrate(&freq));
__wss_outreg(WSSR_COUNT_LOW, 1);
__wss_outreg(WSSR_COUNT_HIGH, 0);
/* Tell codec to start transfer */
__wss_regbit_set(WSSR_IFACE_CTRL, WSSM_PLAYBACK_ENABLE);
_farsetsel(_dos_ds);
timer = _farnspeekl(0x46c);
while (_farnspeekl(0x46c) - timer <= 2)
if (dma_get_count(wss.dma) == 0)
break;
__wss_regbit_reset(WSSR_IFACE_CTRL, WSSM_PLAYBACK_ENABLE);
dma_disable(wss.dma);
/* Now check if DMA transfer count is zero and an IRQ is pending */
status = inportb(WSS_STATUS);
outportb(WSS_STATUS, 0);
if ((dma_get_count(wss.dma) == 0) && (status & WSSM_INT))
break;
wss.dma = 0;
}
if (!wss.dma)
return FALSE;
}
/* Now detect the IRQ number */
if (!wss.irq) {
unsigned int i, irqmask, freq = 5510;
unsigned long timer, delta = 0x7fffffff;
/* IRQ can be one of 2,3,5,7,10 */
irq_detect_start(0x04ac, __wss_irq_irqdetect);
dma_disable(wss.dma);
dma_set_mode(wss.dma, DMA_MODE_WRITE | DMA_MODE_AUTOINIT);
dma_clear_ff(wss.dma);
dma_set_count(wss.dma, 1);
dma_enable(wss.dma);
__wss_setformat(__wss_getrate(&freq));
/* Clear IRQ status */
outportb(WSS_STATUS, 0);
__wss_outreg(WSSR_COUNT_LOW, 0);
__wss_outreg(WSSR_COUNT_HIGH, 0);
/* Prepare timeout counter */
_farsetsel(_dos_ds);
timer = _farnspeekl(0x46c);
while (timer == _farnspeekl(0x46c));
timer = _farnspeekl(0x46c);
/* Reset all IRQ counters */
irq_detect_clear();
/* Tell codec to start transfer */
__wss_regbit_set(WSSR_IFACE_CTRL, WSSM_PLAYBACK_ENABLE);
/* Now wait 1/18 seconds */
while (timer == _farnspeekl(0x46c));
__wss_regbit_reset(WSSR_IFACE_CTRL, WSSM_PLAYBACK_ENABLE);
dma_disable(wss.dma);
/* Given frequency 5510Hz, a buffer size of 1 byte and a time interval
of 1/18.2 second, we should have received about 302 interrupts */
for (i = 2; i <= 10; i++) {
int count = abs(302 - irq_detect_get(i, &irqmask));
if (count < delta)
wss.irq = i, delta = count;
}
if (delta > 150)
wss.irq = 0;
irq_detect_end();
if (!wss.irq)
return FALSE;
}
return TRUE;
}
