trident.c

讲述linux的初始化过程

static void start_adc(struct trident_state *state)
{
	struct dmabuf *dmabuf = &state->dmabuf;
	unsigned int chan_num = dmabuf->channel->num;
	struct trident_card *card = state->card;
	unsigned long flags;

	spin_lock_irqsave(&card->lock, flags);
	if ((dmabuf->mapped || dmabuf->count < (signed)dmabuf->dmasize) && dmabuf->ready) {
		dmabuf->enable |= ADC_RUNNING;
		trident_enable_voice_irq(card, chan_num);
		trident_start_voice(card, chan_num);
	}
	spin_unlock_irqrestore(&card->lock, flags);
}

/* stop playback (lock held) */
extern __inline__ void __stop_dac(struct trident_state *state)
{
	struct dmabuf *dmabuf = &state->dmabuf;
	unsigned int chan_num = dmabuf->channel->num;
	struct trident_card *card = state->card;

	dmabuf->enable &= ~DAC_RUNNING;
	trident_stop_voice(card, chan_num);
	if (state->chans_num == 6) {
		trident_stop_voice(card, state->other_states[0]->dmabuf.channel->num);
		trident_stop_voice(card, state->other_states[1]->dmabuf.channel->num);
		trident_stop_voice(card, state->other_states[2]->dmabuf.channel->num);
		trident_stop_voice(card, state->other_states[3]->dmabuf.channel->num);
	}
	trident_disable_voice_irq(card, chan_num);
}

static void stop_dac(struct trident_state *state)
{
	struct trident_card *card = state->card;
	unsigned long flags;

	spin_lock_irqsave(&card->lock, flags);
	__stop_dac(state);
	spin_unlock_irqrestore(&card->lock, flags);
}	

static void start_dac(struct trident_state *state)
{
	struct dmabuf *dmabuf = &state->dmabuf;
	unsigned int chan_num = dmabuf->channel->num;
	struct trident_card *card = state->card;
	unsigned long flags;

	spin_lock_irqsave(&card->lock, flags);
	if ((dmabuf->mapped || dmabuf->count > 0) && dmabuf->ready) {
		dmabuf->enable |= DAC_RUNNING;
		trident_enable_voice_irq(card, chan_num);
		trident_start_voice(card, chan_num);
		if (state->chans_num == 6) {
			trident_start_voice(card, state->other_states[0]->dmabuf.channel->num);
			trident_start_voice(card, state->other_states[1]->dmabuf.channel->num);
			trident_start_voice(card, state->other_states[2]->dmabuf.channel->num);
			trident_start_voice(card, state->other_states[3]->dmabuf.channel->num);
		}
	}
	spin_unlock_irqrestore(&card->lock, flags);
}

#define DMABUF_DEFAULTORDER (15-PAGE_SHIFT)
#define DMABUF_MINORDER 1

/* allocate DMA buffer, playback and recording buffer should be allocated seperately */
static int alloc_dmabuf(struct trident_state *state)
{
	struct dmabuf *dmabuf = &state->dmabuf;
	void *rawbuf;
	int order;
	struct page *page, *pend;

	/* alloc as big a chunk as we can, FIXME: is this necessary ?? */
	for (order = DMABUF_DEFAULTORDER; order >= DMABUF_MINORDER; order--)
		if ((rawbuf = pci_alloc_consistent(state->card->pci_dev,
						   PAGE_SIZE << order,
						   &dmabuf->dma_handle)))
			break;
	if (!rawbuf)
		return -ENOMEM;

#ifdef DEBUG
	printk("trident: allocated %ld (order = %d) bytes at %p\n",
	       PAGE_SIZE << order, order, rawbuf);
#endif

	dmabuf->ready  = dmabuf->mapped = 0;
	dmabuf->rawbuf = rawbuf;
	dmabuf->buforder = order;
	
	/* now mark the pages as reserved; otherwise remap_page_range doesn't do what we want */
	pend = virt_to_page(rawbuf + (PAGE_SIZE << order) - 1);
	for (page = virt_to_page(rawbuf); page <= pend; page++)
		mem_map_reserve(page);

	return 0;
}

/* free DMA buffer */
static void dealloc_dmabuf(struct trident_state *state)
{
	struct dmabuf *dmabuf = &state->dmabuf;
	struct page *page, *pend;

	if (dmabuf->rawbuf) {
		/* undo marking the pages as reserved */
		pend = virt_to_page(dmabuf->rawbuf + (PAGE_SIZE << dmabuf->buforder) - 1);
		for (page = virt_to_page(dmabuf->rawbuf); page <= pend; page++)
			mem_map_unreserve(page);
		pci_free_consistent(state->card->pci_dev, PAGE_SIZE << dmabuf->buforder,
				    dmabuf->rawbuf, dmabuf->dma_handle);
	}
	dmabuf->rawbuf = NULL;
	dmabuf->mapped = dmabuf->ready = 0;
}

static int prog_dmabuf(struct trident_state *state, unsigned rec)
{
	struct dmabuf *dmabuf = &state->dmabuf;
	unsigned bytepersec;
	struct trident_state *s = state;
	unsigned bufsize, dma_nums;
	unsigned long flags;
	int ret, i, order;
	struct page *page, *pend;
	
	lock_set_fmt(state);
	if (state->chans_num == 6)
		dma_nums = 5;
	else 	dma_nums = 1;
	
	for (i = 0; i < dma_nums; i++) {
		if (i > 0) {
			s = state->other_states[i - 1];			
			dmabuf = &s->dmabuf;
			dmabuf->fmt = state->dmabuf.fmt;
			dmabuf->rate = state->dmabuf.rate;
		}

		spin_lock_irqsave(&s->card->lock, flags);
		dmabuf->hwptr = dmabuf->swptr = dmabuf->total_bytes = 0;
		dmabuf->count = dmabuf->error = 0;
		spin_unlock_irqrestore(&s->card->lock, flags);

		/* allocate DMA buffer if not allocated yet */
		if (!dmabuf->rawbuf) {
			if (i == 0) {
				if ((ret = alloc_dmabuf(state))) {
					unlock_set_fmt(state);
					return ret;
				}
			}
			else {
				if ((order = state->dmabuf.buforder - 1) >= DMABUF_MINORDER)
					dmabuf->rawbuf = (void *)__get_free_pages(GFP_KERNEL | GFP_DMA, order);
				if (!dmabuf->rawbuf) {
					free_pages((unsigned long)state->dmabuf.rawbuf, state->dmabuf.buforder);
					state->dmabuf.rawbuf = NULL;
					i-=2;
					for (; i >= 0; i--)
						free_pages((unsigned long)state->other_states[i]->dmabuf.rawbuf, state->other_states[i]->dmabuf.buforder);
					unlock_set_fmt(state);
					return -ENOMEM;
				}
				dmabuf->ready  = dmabuf->mapped = 0;
				dmabuf->buforder = order;
				pend = virt_to_page(dmabuf->rawbuf + (PAGE_SIZE << order) - 1);
				for (page = virt_to_page(dmabuf->rawbuf); page <= pend; page++)
					mem_map_reserve(page);
			}
		}
		/* FIXME: figure out all this OSS fragment stuff */
		bytepersec = dmabuf->rate << sample_shift[dmabuf->fmt];
		bufsize = PAGE_SIZE << dmabuf->buforder;
		if (dmabuf->ossfragshift) {
			if ((1000 << dmabuf->ossfragshift) < bytepersec)
				dmabuf->fragshift = ld2(bytepersec/1000);
			else
				dmabuf->fragshift = dmabuf->ossfragshift;
		} else {
			/* lets hand out reasonable big ass buffers by default */
			dmabuf->fragshift = (dmabuf->buforder + PAGE_SHIFT -2);
		}
		dmabuf->numfrag = bufsize >> dmabuf->fragshift;
		while (dmabuf->numfrag < 4 && dmabuf->fragshift > 3) {
			dmabuf->fragshift--;
			dmabuf->numfrag = bufsize >> dmabuf->fragshift;
		}
		dmabuf->fragsize = 1 << dmabuf->fragshift;
		if (dmabuf->ossmaxfrags >= 4 && dmabuf->ossmaxfrags < dmabuf->numfrag)
			dmabuf->numfrag = dmabuf->ossmaxfrags;
		dmabuf->fragsamples = dmabuf->fragsize >> sample_shift[dmabuf->fmt];
		dmabuf->dmasize = dmabuf->numfrag << dmabuf->fragshift;

		memset(dmabuf->rawbuf, (dmabuf->fmt & TRIDENT_FMT_16BIT) ? 0 : 0x80,
		       dmabuf->dmasize);

		spin_lock_irqsave(&s->card->lock, flags);
		if (rec) {
			trident_rec_setup(s);
		} else {
			trident_play_setup(s);
		}
		spin_unlock_irqrestore(&s->card->lock, flags);

		/* set the ready flag for the dma buffer */
		dmabuf->ready = 1;

#ifdef DEBUG
	printk("trident: prog_dmabuf(%d), sample rate = %d, format = %d, numfrag = %d, "
	       "fragsize = %d dmasize = %d\n",
	       dmabuf->channel->num, dmabuf->rate, dmabuf->fmt, dmabuf->numfrag,
	       dmabuf->fragsize, dmabuf->dmasize);
#endif
	}
	unlock_set_fmt(state);
	return 0;
}

/* we are doing quantum mechanics here, the buffer can only be empty, half or full filled i.e.
   |------------|------------|   or   |xxxxxxxxxxxx|------------|   or   |xxxxxxxxxxxx|xxxxxxxxxxxx|
   but we almost always get this
   |xxxxxx------|------------|   or   |xxxxxxxxxxxx|xxxxx-------|
   so we have to clear the tail space to "silence"
   |xxxxxx000000|------------|   or   |xxxxxxxxxxxx|xxxxxx000000|
*/
static void trident_clear_tail(struct trident_state *state)
{
	struct dmabuf *dmabuf = &state->dmabuf;
	unsigned swptr;
	unsigned char silence = (dmabuf->fmt & TRIDENT_FMT_16BIT) ? 0 : 0x80;
	unsigned int len;
	unsigned long flags;

	spin_lock_irqsave(&state->card->lock, flags);
	swptr = dmabuf->swptr;
	spin_unlock_irqrestore(&state->card->lock, flags);

	if (swptr == 0 || swptr == dmabuf->dmasize / 2 || swptr == dmabuf->dmasize)
		return;

	if (swptr < dmabuf->dmasize/2)
		len = dmabuf->dmasize/2 - swptr;
	else
		len = dmabuf->dmasize - swptr;

	memset(dmabuf->rawbuf + swptr, silence, len);

	spin_lock_irqsave(&state->card->lock, flags);
	dmabuf->swptr += len;
	dmabuf->count += len;
	spin_unlock_irqrestore(&state->card->lock, flags);

	/* restart the dma machine in case it is halted */
	start_dac(state);
}

static int drain_dac(struct trident_state *state, int nonblock)
{
	DECLARE_WAITQUEUE(wait, current);
	struct dmabuf *dmabuf = &state->dmabuf;
	unsigned long flags;
	unsigned long tmo;
	int count;

	if (dmabuf->mapped || !dmabuf->ready)
		return 0;

	add_wait_queue(&dmabuf->wait, &wait);
	for (;;) {
		/* It seems that we have to set the current state to TASK_INTERRUPTIBLE
		   every time to make the process really go to sleep */
		current->state = TASK_INTERRUPTIBLE;

		spin_lock_irqsave(&state->card->lock, flags);
		count = dmabuf->count;
		spin_unlock_irqrestore(&state->card->lock, flags);

		if (count <= 0)
			break;

		if (signal_pending(current))
			break;

		if (nonblock) {
			remove_wait_queue(&dmabuf->wait, &wait);
			current->state = TASK_RUNNING;
			return -EBUSY;
		}

		/* No matter how much data left in the buffer, we have to wait untill
		   CSO == ESO/2 or CSO == ESO when address engine interrupts */
		tmo = (dmabuf->dmasize * HZ) / dmabuf->rate;
		tmo >>= sample_shift[dmabuf->fmt];
		if (!schedule_timeout(tmo ? tmo : 1) && tmo){
			printk(KERN_ERR "trident: drain_dac, dma timeout?\n");
			break;
		}
	}
	remove_wait_queue(&dmabuf->wait, &wait);
	current->state = TASK_RUNNING;
	if (signal_pending(current))
		return -ERESTARTSYS;

	return 0;
}

/* update buffer manangement pointers, especially, dmabuf->count and dmabuf->hwptr */
static void trident_update_ptr(struct trident_state *state)
{
	struct dmabuf *dmabuf = &state->dmabuf;
	unsigned hwptr, swptr;
	int clear_cnt = 0;
	int diff;
	unsigned char silence;
	unsigned half_dmasize;

	/* update hardware pointer */
	hwptr = trident_get_dma_addr(state);
	diff = (dmabuf->dmasize + hwptr - dmabuf->hwptr) % dmabuf->dmasize;
	dmabuf->hwptr = hwptr;
	dmabuf->total_bytes += diff;

	/* error handling and process wake up for ADC */
	if (dmabuf->enable == ADC_RUNNING) {
		if (dmabuf->mapped) {
			dmabuf->count -= diff;
			if (dmabuf->count >= (signed)dmabuf->fragsize)
				wake_up(&dmabuf->wait);
		} else {
			dmabuf->count += diff;

			if (dmabuf->count < 0 || dmabuf->count > dmabuf->dmasize) {
				/* buffer underrun or buffer overrun, we have no way to recover
				   it here, just stop the machine and let the process force hwptr
				   and swptr to sync */
				__stop_adc(state);
				dmabuf->error++;
			}
			if (dmabuf->count < (signed)dmabuf->dmasize/2)
				wake_up(&dmabuf->wait);
		}
	}

	/* error handling and process wake up for DAC */
	if (dmabuf->enable == DAC_RUNNING) {
		if (dmabuf->mapped) {
			dmabuf->count += diff;
			if (dmabuf->count >= (signed)dmabuf->fragsize)
				wake_up(&dmabuf->wait);
		} else {
			dmabuf->count -= diff;

			if (dmabuf->count < 0 || dmabuf->count > dmabuf->dmasize) {
				/* buffer underrun or buffer overrun, we have no way to recover
				   it here, just stop the machine and let the process force hwptr
				   and swptr to sync */
				__stop_dac(state);
				dmabuf->error++;
			}
			else if (!dmabuf->endcleared) {
				swptr = dmabuf->swptr;
				silence = (dmabuf->fmt & TRIDENT_FMT_16BIT ? 0 : 0x80);
				if (dmabuf->update_flag & ALI_ADDRESS_INT_UPDATE) {
					/* We must clear end data of 1/2 dmabuf if needed.
					   According to 1/2 algorithm of Address Engine Interrupt,
					   check the validation of the data of half dmasize. */
					half_dmasize = dmabuf->dmasize / 2;
					if ((diff = hwptr - half_dmasize) < 0 )
						diff = hwptr;
					if ((dmabuf->count + diff) < half_dmasize) {
						//there is invalid data in the end of half buffer
						if ((clear_cnt = half_dmasize - swptr) < 0)
							clear_cnt += half_dmasize;
						//clear the invalid data
						memset (dmabuf->rawbuf + swptr,
							silence, clear_cnt);
						if (state->chans_num == 6) {
						clear_cnt = clear_cnt / 2;
						swptr = swptr / 2;
							memset (state->other_states[0]->dmabuf.rawbuf + swptr,
								silence, clear_cnt);
							memset (state->other_states[1]->dmabuf.rawbuf + swptr,
								silence, clear_cnt);
							memset (state->other_states[2]->dmabuf.rawbuf + swptr,
								silence, clear_cnt);
							memset (state->other_states[3]->dmabuf.rawbuf + swptr,
								silence, clear_cnt);
						}
						dmabuf->endcleared = 1;
					}
				} else if (dmabuf->count < (signed) dmabuf->fragsize) {
					clear_cnt = dmabuf->fragsize;
					if ((swptr + clear_cnt) > dmabuf->dmasize)
						clear_cnt = dmabuf->dmasize - swptr;
					memset (dmabuf->rawbuf + swptr, silence, clear_cnt);
					if (state->chans_num == 6) {
						clear_cnt = clear_cnt / 2;
						swptr = swptr / 2;
						memset (state->other_states[0]->dmabuf.rawbuf + swptr,
							silence, clear_cnt);
						memset (state->other_states[1]->dmabuf.rawbuf + swptr,
							silence, clear_cnt);
						memset (state->other_states[2]->dmabuf.rawbuf + swptr,
							silence, clear_cnt);
						memset (state->other_states[3]->dmabuf.rawbuf + swptr,
							silence, clear_cnt);
					}
					dmabuf->endcleared = 1;
				}
			}
			/* trident_update_ptr is called by interrupt handler or by process via
			   ioctl/poll, we only wake up the waiting process when we have more
			   than 1/2 buffer free (always true for interrupt handler) */
			if (dmabuf->count < (signed)dmabuf->dmasize/2)
				wake_up(&dmabuf->wait);
		}
	}
	dmabuf->update_flag &= ~ALI_ADDRESS_INT_UPDATE;
}

static void trident_address_interrupt(struct trident_card *card)
{
	int i;
	struct trident_state *state;
	
	/* Update the pointers for all channels we are running. */
	/* FIXME: should read interrupt status only once */
	for (i = 0; i < NR_HW_CH; i++) {
		if (trident_check_channel_interrupt(card, 63 - i)) {
			trident_ack_channel_interrupt(card, 63 - i);
			if ((state = card->states[i]) != NULL) {
				trident_update_ptr(state);
			} else {
				printk("trident: spurious channel irq %d.\n",
				       63 - i);
				trident_stop_voice(card, 63 - i);
				trident_disable_voice_irq(card, 63 - i);
			}