C++ release_dma_lock函数代码示例

static void handlewrite(struct net_device *dev)
{
	/* called *only* from idle, non-reentrant */
	/* on entry, 0xfb and ltdmabuf holds data */
	int dma = dev->dma;
	int base = dev->base_addr;
	unsigned long flags;
	
	flags=claim_dma_lock();
	disable_dma(dma);
	clear_dma_ff(dma);
	set_dma_mode(dma,DMA_MODE_WRITE);
	set_dma_addr(dma,virt_to_bus(ltdmabuf));
	set_dma_count(dma,800);
	enable_dma(dma);
	release_dma_lock(flags);
	
	inb_p(base+3);
	inb_p(base+2);

	if ( wait_timeout(dev,0xfb) ) {
		flags=claim_dma_lock();
		printk("timed out in handlewrite, dma res %d\n",
			get_dma_residue(dev->dma) );
		release_dma_lock(flags);
	}
}

/* Request needed resources */
static int znet_request_resources (struct net_device *dev)
{
	struct znet_private *znet = netdev_priv(dev);
	unsigned long flags;

	if (request_irq (dev->irq, &znet_interrupt, 0, "ZNet", dev))
		goto failed;
	if (request_dma (znet->rx_dma, "ZNet rx"))
		goto free_irq;
	if (request_dma (znet->tx_dma, "ZNet tx"))
		goto free_rx_dma;
	if (!request_region (znet->sia_base, znet->sia_size, "ZNet SIA"))
		goto free_tx_dma;
	if (!request_region (dev->base_addr, znet->io_size, "ZNet I/O"))
		goto free_sia;

	return 0;				/* Happy ! */

 free_sia:
	release_region (znet->sia_base, znet->sia_size);
 free_tx_dma:
	flags = claim_dma_lock();
	free_dma (znet->tx_dma);
	release_dma_lock (flags);
 free_rx_dma:
	flags = claim_dma_lock();
	free_dma (znet->rx_dma);
	release_dma_lock (flags);
 free_irq:
	free_irq (dev->irq, dev);
 failed:
	return -1;
}

static ssize_t __dma_write(gpib_board_t *board, nec7210_private_t *priv, dma_addr_t address, size_t length)
{
	unsigned long flags, dma_irq_flags;
	int residue = 0;
	int retval = 0;

	spin_lock_irqsave(&board->spinlock, flags);

	/* program dma controller */
	dma_irq_flags = claim_dma_lock();
	disable_dma(priv->dma_channel);
	clear_dma_ff(priv->dma_channel);
	set_dma_count(priv->dma_channel, length);
	set_dma_addr(priv->dma_channel, address);
	set_dma_mode(priv->dma_channel, DMA_MODE_WRITE );
	enable_dma(priv->dma_channel);
	release_dma_lock(dma_irq_flags);

	// enable board's dma for output
	nec7210_set_reg_bits( priv, IMR2, HR_DMAO, HR_DMAO );

	clear_bit(WRITE_READY_BN, &priv->state);
	set_bit(DMA_WRITE_IN_PROGRESS_BN, &priv->state);

	spin_unlock_irqrestore(&board->spinlock, flags);

	// suspend until message is sent
	if(wait_event_interruptible(board->wait, test_bit(DMA_WRITE_IN_PROGRESS_BN, &priv->state) == 0 ||
		test_bit( BUS_ERROR_BN, &priv->state ) || test_bit( DEV_CLEAR_BN, &priv->state ) ||
		test_bit(TIMO_NUM, &board->status)))
	{
		GPIB_DPRINTK( "gpib write interrupted!\n" );
		retval = -ERESTARTSYS;
	}
	if(test_bit(TIMO_NUM, &board->status))
		retval = -ETIMEDOUT;
	if( test_and_clear_bit( DEV_CLEAR_BN, &priv->state ) )
		retval = -EINTR;
	if( test_and_clear_bit( BUS_ERROR_BN, &priv->state ) )
		retval = -EIO;

	// disable board's dma
	nec7210_set_reg_bits( priv, IMR2, HR_DMAO, 0 );

	dma_irq_flags = claim_dma_lock();
	clear_dma_ff(priv->dma_channel);
	disable_dma(priv->dma_channel);
	residue = get_dma_residue(priv->dma_channel);
	release_dma_lock( dma_irq_flags );

	if(residue)
		retval = -EPIPE;

	return retval ? retval : length;
}

/* called in irq context */
void DMAbuf_inputintr(int dev)
{
	struct audio_operations *adev = audio_devs[dev];
	struct dma_buffparms *dmap = adev->dmap_in;
	unsigned long flags;

	spin_lock_irqsave(&dmap->lock,flags);

	if (!(dmap->flags & DMA_NODMA)) {
		int chan = dmap->dma, pos, n;
		unsigned long f;
		
		f=claim_dma_lock();
		if(!isa_dma_bridge_buggy)
			disable_dma(dmap->dma);
		clear_dma_ff(chan);
		pos = dmap->bytes_in_use - get_dma_residue(chan);
		if(!isa_dma_bridge_buggy)
			enable_dma(dmap->dma);
		release_dma_lock(f);

		pos = pos / dmap->fragment_size;	/* Actual qhead */
		if (pos < 0 || pos >= dmap->nbufs)
			pos = 0;

		n = 0;
		while (dmap->qtail != pos && ++n < dmap->nbufs)
			do_inputintr(dev);
	} else
		do_inputintr(dev);
	spin_unlock_irqrestore(&dmap->lock,flags);
}

int labpc_init_dma_chan(struct comedi_device *dev, unsigned int dma_chan)
{
	struct labpc_private *devpriv = dev->private;
	void *dma_buffer;
	unsigned long dma_flags;
	int ret;

	if (dma_chan != 1 && dma_chan != 3)
		return -EINVAL;

	dma_buffer = kmalloc(dma_buffer_size, GFP_KERNEL | GFP_DMA);
	if (!dma_buffer)
		return -ENOMEM;

	ret = request_dma(dma_chan, dev->board_name);
	if (ret) {
		kfree(dma_buffer);
		return ret;
	}

	devpriv->dma_buffer = dma_buffer;
	devpriv->dma_chan = dma_chan;
	devpriv->dma_addr = virt_to_bus(devpriv->dma_buffer);

	dma_flags = claim_dma_lock();
	disable_dma(devpriv->dma_chan);
	set_dma_mode(devpriv->dma_chan, DMA_MODE_READ);
	release_dma_lock(dma_flags);

	return 0;
}

static void wbsd_request_end(struct wbsd_host *host, struct mmc_request *mrq)
{
	unsigned long dmaflags;

	if (host->dma >= 0) {
		/*
		 * Release ISA DMA controller.
		 */
		dmaflags = claim_dma_lock();
		disable_dma(host->dma);
		clear_dma_ff(host->dma);
		release_dma_lock(dmaflags);

		/*
		 * Disable DMA on host.
		 */
		wbsd_write_index(host, WBSD_IDX_DMA, 0);
	}

	host->mrq = NULL;

	/*
	 * MMC layer might call back into the driver so first unlock.
	 */
	spin_unlock(&host->lock);
	mmc_request_done(host->mmc, mrq);
	spin_lock(&host->lock);
}

void DMAbuf_outputintr(int dev, int notify_only)
{
	struct audio_operations *adev = audio_devs[dev];
	unsigned long flags;
	struct dma_buffparms *dmap = adev->dmap_out;

	save_flags(flags);
	cli();
	if (!(dmap->flags & DMA_NODMA)) {
		int chan = dmap->dma, pos, n;
		unsigned long f;
		
		f=claim_dma_lock();
		
		if(!isa_dma_bridge_buggy)
			disable_dma(dmap->dma);
		clear_dma_ff(chan);
		pos = dmap->bytes_in_use - get_dma_residue(chan);
		if(!isa_dma_bridge_buggy)
			enable_dma(dmap->dma);
		release_dma_lock(f);
		
		pos = pos / dmap->fragment_size;	/* Actual qhead */
		if (pos < 0 || pos >= dmap->nbufs)
			pos = 0;
		n = 0;
		while (dmap->qhead != pos && n++ < dmap->nbufs)
			do_outputintr(dev, notify_only);
	}
	else
		do_outputintr(dev, notify_only);
	restore_flags(flags);
}

static __inline__ int 
NCR53c406a_dma_setup (unsigned char *ptr, 
		      unsigned int count, 
		      unsigned char mode) {
    unsigned limit;
    unsigned long flags = 0;
    
    VDEB(printk("dma: before count=%d   ", count));
    if (dma_chan <=3) {
        if (count > 65536)
            count = 65536;
        limit = 65536 - (((unsigned) ptr) & 0xFFFF);
    } else {
        if (count > (65536<<1)) 
            count = (65536<<1);
        limit = (65536<<1) - (((unsigned) ptr) & 0x1FFFF);
    }
    
    if (count > limit) count = limit;
    
    VDEB(printk("after count=%d\n", count));
    if ((count & 1) || (((unsigned) ptr) & 1))
        panic ("NCR53c406a: attempted unaligned DMA transfer\n"); 
    
    flags=claim_dma_lock();
    disable_dma(dma_chan);
    clear_dma_ff(dma_chan);
    set_dma_addr(dma_chan, (long) ptr);
    set_dma_count(dma_chan, count);
    set_dma_mode(dma_chan, mode);
    enable_dma(dma_chan);
    release_dma_lock(flags);    
    
    return count;
}

static void receive_packet(struct net_device *dev, int len)
{
	int rlen;
	elp_device *adapter = dev->priv;
	void *target;
	struct sk_buff *skb;
	unsigned long flags;

	rlen = (len + 1) & ~1;
	skb = dev_alloc_skb(rlen + 2);

	if (!skb) {
		printk(KERN_WARNING "%s: memory squeeze, dropping packet\n", dev->name);
		target = adapter->dma_buffer;
		adapter->current_dma.target = NULL;
		/* FIXME: stats */
		return;
	}

	skb_reserve(skb, 2);
	target = skb_put(skb, rlen);
	if ((unsigned long)(target + rlen) >= MAX_DMA_ADDRESS) {
		adapter->current_dma.target = target;
		target = adapter->dma_buffer;
	} else {
		adapter->current_dma.target = NULL;
	}

	/* if this happens, we die */
	if (test_and_set_bit(0, (void *) &adapter->dmaing))
		printk(KERN_ERR "%s: rx blocked, DMA in progress, dir %d\n", dev->name, adapter->current_dma.direction);

	skb->dev = dev;
	adapter->current_dma.direction = 0;
	adapter->current_dma.length = rlen;
	adapter->current_dma.skb = skb;
	adapter->current_dma.start_time = jiffies;

	outb_control(adapter->hcr_val | DIR | TCEN | DMAE, dev);

	flags=claim_dma_lock();
	disable_dma(dev->dma);
	clear_dma_ff(dev->dma);
	set_dma_mode(dev->dma, 0x04);	/* dma read */
	set_dma_addr(dev->dma, isa_virt_to_bus(target));
	set_dma_count(dev->dma, rlen);
	enable_dma(dev->dma);
	release_dma_lock(flags);

	if (elp_debug >= 3) {
		printk(KERN_DEBUG "%s: rx DMA transfer started\n", dev->name);
	}

	if (adapter->rx_active)
		adapter->rx_active--;

	if (!adapter->busy)
		printk(KERN_WARNING "%s: receive_packet called, busy not set.\n", dev->name);
}

static void wbsd_finish_data(struct wbsd_host* host, struct mmc_data* data)
{
	unsigned long dmaflags;
	int count;
	
	WARN_ON(host->mrq == NULL);

	/*
	 * Send a stop command if needed.
	 */
	if (data->stop)
		wbsd_send_command(host, data->stop);
	
	/*
	 * DMA transfer?
	 */
	if (host->dma >= 0)
	{
		/*
		 * Disable DMA on the host.
		 */
		wbsd_write_index(host, WBSD_IDX_DMA, 0);
		
		/*
		 * Turn of ISA DMA controller.
		 */
		dmaflags = claim_dma_lock();
		disable_dma(host->dma);
		clear_dma_ff(host->dma);
		count = get_dma_residue(host->dma);
		release_dma_lock(dmaflags);
		
		/*
		 * Any leftover data?
		 */
		if (count)
		{
			printk(KERN_ERR DRIVER_NAME ": Incomplete DMA "
				"transfer. %d bytes left.\n", count);
			
			data->error = MMC_ERR_FAILED;
		}
		else
		{
			/*
			 * Transfer data from DMA buffer to
			 * SG list.
			 */
			if (data->flags & MMC_DATA_READ)
				wbsd_dma_to_sg(host, data);
			
			data->bytes_xfered = host->size;
		}
	}
	
	DBGF("Ending data transfer (%d bytes)\n", data->bytes_xfered);
	
	wbsd_request_end(host, host->mrq);
}

static netdev_tx_t send_packet(struct net_device *dev, struct sk_buff *skb)
{
	elp_device *adapter = netdev_priv(dev);
	unsigned long target;
	unsigned long flags;

	unsigned int nlen = (((skb->len < 60) ? 60 : skb->len) + 1) & (~1);

	if (test_and_set_bit(0, (void *) &adapter->busy)) {
		if (elp_debug >= 2)
			pr_debug("%s: transmit blocked\n", dev->name);
		return false;
	}

	dev->stats.tx_bytes += nlen;

	adapter->tx_pcb.command = CMD_TRANSMIT_PACKET;
	adapter->tx_pcb.length = sizeof(struct Xmit_pkt);
	adapter->tx_pcb.data.xmit_pkt.buf_ofs
	    = adapter->tx_pcb.data.xmit_pkt.buf_seg = 0;	
	adapter->tx_pcb.data.xmit_pkt.pkt_len = nlen;

	if (!send_pcb(dev, &adapter->tx_pcb)) {
		adapter->busy = 0;
		return false;
	}
	
	if (test_and_set_bit(0, (void *) &adapter->dmaing))
		pr_debug("%s: tx: DMA %d in progress\n", dev->name, adapter->current_dma.direction);

	adapter->current_dma.direction = 1;
	adapter->current_dma.start_time = jiffies;

	if ((unsigned long)(skb->data + nlen) >= MAX_DMA_ADDRESS || nlen != skb->len) {
		skb_copy_from_linear_data(skb, adapter->dma_buffer, nlen);
		memset(adapter->dma_buffer+skb->len, 0, nlen-skb->len);
		target = isa_virt_to_bus(adapter->dma_buffer);
	}
	else {
		target = isa_virt_to_bus(skb->data);
	}
	adapter->current_dma.skb = skb;

	flags=claim_dma_lock();
	disable_dma(dev->dma);
	clear_dma_ff(dev->dma);
	set_dma_mode(dev->dma, 0x48);	
	set_dma_addr(dev->dma, target);
	set_dma_count(dev->dma, nlen);
	outb_control(adapter->hcr_val | DMAE | TCEN, dev);
	enable_dma(dev->dma);
	release_dma_lock(flags);

	if (elp_debug >= 3)
		pr_debug("%s: DMA transfer started\n", dev->name);

	return true;
}

/**
 * snd_dma_disable - stop the ISA DMA transfer
 * @dma: the dma number
 *
 * Stops the ISA DMA transfer.
 */
void snd_dma_disable(unsigned long dma)
{
	unsigned long flags;

	flags = claim_dma_lock();
	clear_dma_ff(dma);
	disable_dma(dma);
	release_dma_lock(flags);
}

void labpc_drain_dma(struct comedi_device *dev)
{
	struct labpc_private *devpriv = dev->private;
	struct comedi_subdevice *s = dev->read_subdev;
	struct comedi_async *async = s->async;
	struct comedi_cmd *cmd = &async->cmd;
	int status;
	unsigned long flags;
	unsigned int max_points, num_points, residue, leftover;
	int i;

	status = devpriv->stat1;

	flags = claim_dma_lock();
	disable_dma(devpriv->dma_chan);
	/* clear flip-flop to make sure 2-byte registers for
	 * count and address get set correctly */
	clear_dma_ff(devpriv->dma_chan);

	/* figure out how many points to read */
	max_points = devpriv->dma_transfer_size / sample_size;
	/* residue is the number of points left to be done on the dma
	 * transfer.  It should always be zero at this point unless
	 * the stop_src is set to external triggering.
	 */
	residue = get_dma_residue(devpriv->dma_chan) / sample_size;
	num_points = max_points - residue;
	if (cmd->stop_src == TRIG_COUNT && devpriv->count < num_points)
		num_points = devpriv->count;

	/* figure out how many points will be stored next time */
	leftover = 0;
	if (cmd->stop_src != TRIG_COUNT) {
		leftover = devpriv->dma_transfer_size / sample_size;
	} else if (devpriv->count > num_points) {
		leftover = devpriv->count - num_points;
		if (leftover > max_points)
			leftover = max_points;
	}

	/* write data to comedi buffer */
	for (i = 0; i < num_points; i++)
		cfc_write_to_buffer(s, devpriv->dma_buffer[i]);

	if (cmd->stop_src == TRIG_COUNT)
		devpriv->count -= num_points;

	/* set address and count for next transfer */
	set_dma_addr(devpriv->dma_chan, devpriv->dma_addr);
	set_dma_count(devpriv->dma_chan, leftover * sample_size);
	release_dma_lock(flags);

	async->events |= COMEDI_CB_BLOCK;
}

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;
}

static __inline__ int 
NCR53c406a_dma_residual (void) {
    register int tmp;
    unsigned long flags;

    flags=claim_dma_lock();
    clear_dma_ff(dma_chan);
    tmp = get_dma_residue(dma_chan);
    release_dma_lock(flags);
    
    return tmp;
}