dmabuf.c

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		dmap = adev->dmap_out;
		save_flags(flags);
		cli();
		if (dmap->qlen > 0 && !(dmap->flags & DMA_ACTIVE))
			DMAbuf_launch_output(dev, dmap);
		adev->dmap_out->flags |= DMA_SYNCING;
		adev->dmap_out->underrun_count = 0;
		while (!signal_pending(current) && n++ <= adev->dmap_out->nbufs && 
		       adev->dmap_out->qlen && adev->dmap_out->underrun_count == 0) {
			long t = dmabuf_timeout(dmap);
			t = interruptible_sleep_on_timeout(&adev->out_sleeper,
							   t);
			if (!t) {
				adev->dmap_out->flags &= ~DMA_SYNCING;
				restore_flags(flags);
				return adev->dmap_out->qlen;
			}
		}
		adev->dmap_out->flags &= ~(DMA_SYNCING | DMA_ACTIVE);
		restore_flags(flags);
		
		/*
		 * Some devices such as GUS have huge amount of on board RAM for the
		 * audio data. We have to wait until the device has finished playing.
		 */

		save_flags(flags);
		cli();
		if (adev->d->local_qlen) {   /* Device has hidden buffers */
			while (!signal_pending(current) &&
			       adev->d->local_qlen(dev))
				interruptible_sleep_on_timeout(&adev->out_sleeper,
							       dmabuf_timeout(dmap));
		}
		restore_flags(flags);
	}
	adev->dmap_out->dma_mode = DMODE_NONE;
	return adev->dmap_out->qlen;
}

int DMAbuf_release(int dev, int mode)
{
	struct audio_operations *adev = audio_devs[dev];
	unsigned long flags;

	if (adev->open_mode & OPEN_WRITE)
		adev->dmap_out->closing = 1;
	if (adev->open_mode & OPEN_READ)
		adev->dmap_in->closing = 1;

	if (adev->open_mode & OPEN_WRITE)
		if (!(adev->dmap_out->mapping_flags & DMA_MAP_MAPPED))
			if (!signal_pending(current) && (adev->dmap_out->dma_mode == DMODE_OUTPUT))
				DMAbuf_sync(dev);
	if (adev->dmap_out->dma_mode == DMODE_OUTPUT)
		memset(adev->dmap_out->raw_buf, adev->dmap_out->neutral_byte, adev->dmap_out->bytes_in_use);
	save_flags(flags);
	cli();

	DMAbuf_reset(dev);
	adev->d->close(dev);

	if (adev->open_mode & OPEN_WRITE)
		close_dmap(adev, adev->dmap_out);

	if (adev->open_mode == OPEN_READ ||
	    (adev->open_mode != OPEN_WRITE &&
	     (adev->flags & DMA_DUPLEX)))
		close_dmap(adev, adev->dmap_in);
	adev->open_mode = 0;
	restore_flags(flags);
	return 0;
}

int DMAbuf_activate_recording(int dev, struct dma_buffparms *dmap)
{
	struct audio_operations *adev = audio_devs[dev];
	int  err;

	if (!(adev->open_mode & OPEN_READ))
		return 0;
	if (!(adev->enable_bits & PCM_ENABLE_INPUT))
		return 0;
	if (dmap->dma_mode == DMODE_OUTPUT) {	/* Direction change */
		DMAbuf_sync(dev);
		DMAbuf_reset(dev);
		dmap->dma_mode = DMODE_NONE;
	}
	if (!dmap->dma_mode) {
		reorganize_buffers(dev, dmap, 1);
		if ((err = adev->d->prepare_for_input(dev,
				dmap->fragment_size, dmap->nbufs)) < 0)
			return err;
		dmap->dma_mode = DMODE_INPUT;
	}
	if (!(dmap->flags & DMA_ACTIVE)) {
		if (dmap->needs_reorg)
			reorganize_buffers(dev, dmap, 0);
		local_start_dma(adev, dmap->raw_buf_phys, dmap->bytes_in_use, DMA_MODE_READ);
		adev->d->start_input(dev, dmap->raw_buf_phys + dmap->qtail * dmap->fragment_size,
				     dmap->fragment_size, 0);
		dmap->flags |= DMA_ACTIVE;
		if (adev->d->trigger)
			adev->d->trigger(dev, adev->enable_bits * adev->go);
	}
	return 0;
}

int DMAbuf_getrdbuffer(int dev, char **buf, int *len, int dontblock)
{
	struct audio_operations *adev = audio_devs[dev];
	unsigned long flags;
	int err = 0, n = 0;
	struct dma_buffparms *dmap = adev->dmap_in;
	int go;

	if (!(adev->open_mode & OPEN_READ))
		return -EIO;
	if (dmap->needs_reorg)
		reorganize_buffers(dev, dmap, 0);
	save_flags(flags);
	cli();
	if (adev->dmap_in->mapping_flags & DMA_MAP_MAPPED) {
/*		  printk(KERN_WARNING "Sound: Can't read from mmapped device (1)\n");*/
		  restore_flags(flags);
		  return -EINVAL;
	} else while (dmap->qlen <= 0 && n++ < 10) {
		long timeout = MAX_SCHEDULE_TIMEOUT;
		if (!(adev->enable_bits & PCM_ENABLE_INPUT) || !adev->go) {
			restore_flags(flags);
			return -EAGAIN;
		}
		if ((err = DMAbuf_activate_recording(dev, dmap)) < 0) {
			restore_flags(flags);
			return err;
		}
		/* Wait for the next block */

		if (dontblock) {
			restore_flags(flags);
			return -EAGAIN;
		}
		if ((go = adev->go))
			timeout = dmabuf_timeout(dmap);
		timeout = interruptible_sleep_on_timeout(&adev->in_sleeper,
							 timeout);
		if (!timeout) {
			/* FIXME: include device name */
			err = -EIO;
			printk(KERN_WARNING "Sound: DMA (input) timed out - IRQ/DRQ config error?\n");
			dma_reset_input(dev);
		} else
			err = -EINTR;
	}
	restore_flags(flags);

	if (dmap->qlen <= 0)
		return err ? err : -EINTR;
	*buf = &dmap->raw_buf[dmap->qhead * dmap->fragment_size + dmap->counts[dmap->qhead]];
	*len = dmap->fragment_size - dmap->counts[dmap->qhead];

	return dmap->qhead;
}

int DMAbuf_rmchars(int dev, int buff_no, int c)
{
	struct audio_operations *adev = audio_devs[dev];
	struct dma_buffparms *dmap = adev->dmap_in;
	int p = dmap->counts[dmap->qhead] + c;

	if (dmap->mapping_flags & DMA_MAP_MAPPED)
	{
/*		  printk("Sound: Can't read from mmapped device (2)\n");*/
		return -EINVAL;
	}
	else if (dmap->qlen <= 0)
		return -EIO;
	else if (p >= dmap->fragment_size) {  /* This buffer is completely empty */
		dmap->counts[dmap->qhead] = 0;
		dmap->qlen--;
		dmap->qhead = (dmap->qhead + 1) % dmap->nbufs;
	}
	else dmap->counts[dmap->qhead] = p;

	return 0;
}

int DMAbuf_get_buffer_pointer(int dev, struct dma_buffparms *dmap, int direction)
{
	/*
	 *	Try to approximate the active byte position of the DMA pointer within the
	 *	buffer area as well as possible.
	 */

	int pos;
	unsigned long flags;
	unsigned long f;

	save_flags(flags);
	cli();
	if (!(dmap->flags & DMA_ACTIVE))
		pos = 0;
	else {
		int chan = dmap->dma;
		
		f=claim_dma_lock();
		clear_dma_ff(chan);
		
		if(!isa_dma_bridge_buggy)
			disable_dma(dmap->dma);
		
		pos = get_dma_residue(chan);
		
		pos = dmap->bytes_in_use - pos;

		if (!(dmap->mapping_flags & DMA_MAP_MAPPED)) {
			if (direction == DMODE_OUTPUT) {
				if (dmap->qhead == 0)
					if (pos > dmap->fragment_size)
						pos = 0;
			} else {
				if (dmap->qtail == 0)
					if (pos > dmap->fragment_size)
						pos = 0;
			}
		}
		if (pos < 0)
			pos = 0;
		if (pos >= dmap->bytes_in_use)
			pos = 0;
		
		if(!isa_dma_bridge_buggy)
			enable_dma(dmap->dma);
			
		release_dma_lock(f);
	}
	restore_flags(flags);
	/* printk( "%04x ",  pos); */

	return pos;
}

/*
 *	DMAbuf_start_devices() is called by the /dev/music driver to start
 *	one or more audio devices at desired moment.
 */

void DMAbuf_start_devices(unsigned int devmask)
{
	struct audio_operations *adev;
	int dev;

	for (dev = 0; dev < num_audiodevs; dev++) {
		if (!(devmask & (1 << dev)))
			continue;
		if (!(adev = audio_devs[dev]))
			continue;
		if (adev->open_mode == 0)
			continue;
		if (adev->go)
			continue;
		/* OK to start the device */
		adev->go = 1;
		if (adev->d->trigger)
			adev->d->trigger(dev,adev->enable_bits * adev->go);
	}
}

int DMAbuf_space_in_queue(int dev)
{
	struct audio_operations *adev = audio_devs[dev];
	int len, max, tmp;
	struct dma_buffparms *dmap = adev->dmap_out;
	int lim = dmap->nbufs;

	if (lim < 2)
		lim = 2;

	if (dmap->qlen >= lim)	/* No space at all */
		return 0;

	/*
	 *	Verify that there are no more pending buffers than the limit
	 *	defined by the process.
	 */

	max = dmap->max_fragments;
	if (max > lim)
		max = lim;
	len = dmap->qlen;

	if (adev->d->local_qlen) {
		tmp = adev->d->local_qlen(dev);
		if (tmp && len)
			tmp--;	/* This buffer has been counted twice */
		len += tmp;
	}
	if (dmap->byte_counter % dmap->fragment_size)	/* There is a partial fragment */
		len = len + 1;

	if (len >= max)
		return 0;
	return max - len;
}

static int output_sleep(int dev, int dontblock)
{
	struct audio_operations *adev = audio_devs[dev];
	int err = 0;
	struct dma_buffparms *dmap = adev->dmap_out;
	long timeout;
	long timeout_value;

	if (dontblock)
		return -EAGAIN;
	if (!(adev->enable_bits & PCM_ENABLE_OUTPUT))
		return -EAGAIN;

	/*
	 * Wait for free space
	 */
	if (signal_pending(current))
		return -EINTR;
	timeout = (adev->go && !(dmap->flags & DMA_NOTIMEOUT));
	if (timeout) 
		timeout_value = dmabuf_timeout(dmap);
	else
		timeout_value = MAX_SCHEDULE_TIMEOUT;
	timeout_value = interruptible_sleep_on_timeout(&adev->out_sleeper,
						       timeout_value);
	if (timeout != MAX_SCHEDULE_TIMEOUT && !timeout_value) {
		printk(KERN_WARNING "Sound: DMA (output) timed out - IRQ/DRQ config error?\n");
		dma_reset_output(dev);
	} else {
		if (signal_pending(current))
			err = -EINTR;
	}
	return err;
}

static int find_output_space(int dev, char **buf, int *size)
{
	struct audio_operations *adev = audio_devs[dev];
	struct dma_buffparms *dmap = adev->dmap_out;
	unsigned long flags;
	unsigned long active_offs;
	long len, offs;
	int maxfrags;
	int occupied_bytes = (dmap->user_counter % dmap->fragment_size);

	*buf = dmap->raw_buf;
	if (!(maxfrags = DMAbuf_space_in_queue(dev)) && !occupied_bytes)
		return 0;
	save_flags(flags);
	cli();

#ifdef BE_CONSERVATIVE
	active_offs = dmap->byte_counter + dmap->qhead * dmap->fragment_size;
#else
	active_offs = DMAbuf_get_buffer_pointer(dev, dmap, DMODE_OUTPUT);
	/* Check for pointer wrapping situation */
	if (active_offs < 0 || active_offs >= dmap->bytes_in_use)
		active_offs = 0;
	active_offs += dmap->byte_counter;
#endif

	offs = (dmap->user_counter % dmap->bytes_in_use) & ~SAMPLE_ROUNDUP;
	if (offs < 0 || offs >= dmap->bytes_in_use) {
		restore_flags(flags);
		printk(KERN_ERR "Sound: Got unexpected offs %ld. Giving up.\n", offs);
		printk("Counter = %ld, bytes=%d\n", dmap->user_counter, dmap->bytes_in_use);
		return 0;
	}
	*buf = dmap->raw_buf + offs;

	len = active_offs + dmap->bytes_in_use - dmap->user_counter;	/* Number of unused bytes in buffer */

	if ((offs + len) > dmap->bytes_in_use)
		len = dmap->bytes_in_use - offs;
	if (len < 0) {
		restore_flags(flags);
		return 0;
	}
	if (len > ((maxfrags * dmap->fragment_size) - occupied_bytes))
		len = (maxfrags * dmap->fragment_size) - occupied_bytes;
	*size = len & ~SAMPLE_ROUNDUP;
	restore_flags(flags);
	return (*size > 0);
}

int DMAbuf_getwrbuffer(int dev, char **buf, int *size, int dontblock)
{
	struct audio_operations *adev = audio_devs[dev];
	unsigned long flags;
	int err = -EIO;
	struct dma_buffparms *dmap = adev->dmap_out;

	if (dmap->needs_reorg)
		reorganize_buffers(dev, dmap, 0);

	if (dmap->mapping_flags & DMA_MAP_MAPPED) {
/*		printk(KERN_DEBUG "Sound: Can't write to mmapped device (3)\n");*/
		return -EINVAL;
	}
	if (dmap->dma_mode == DMODE_INPUT) {	/* Direction change */
		DMAbuf_reset(dev);
		dmap->dma_mode = DMODE_NONE;
	}
	dmap->dma_mode = DMODE_OUTPUT;

	save_flags(flags);
	cli();
	while (find_output_space(dev, buf, size) <= 0) {
		if ((err = output_sleep(dev, dontblock)) < 0) {
			restore_flags(flags);
			return err;
		}
	}
	restore_flags(flags);

	return 0;
}

int DMAbuf_move_wrpointer(int dev, int l)
{
	struct audio_operations *adev = audio_devs[dev];
	struct dma_buffparms *dmap = adev->dmap_out;
	unsigned long ptr = (dmap->user_counter / dmap->fragment_size) * dmap->fragment_size;
	unsigned long end_ptr, p;
	int post = (dmap->flags & DMA_POST);

	dmap->flags &= ~DMA_POST;
	dmap->cfrag = -1;