C++ enable_dma函数代码示例

static void setup_DMA(void) {

	unsigned long addr,count;
	unsigned char dma_code;
	dma_code = DMA_WRITE;
	if (command == FD_READ)
		dma_code = DMA_READ;
	if (command == FD_FORMAT) {
		addr = (long) tmp_floppy_area;
		count = floppy->sect*4;
	} else {
		addr = (long) CURRENT->buffer;
		count = 1024;
	}
	if (read_track) {
/* mark buffer-track bad, in case all this fails.. */
		buffer_drive = buffer_track = -1;
		count = floppy->sect*floppy->head*512;
		addr = (long) floppy_track_buffer;
	} else if (addr >= LAST_DMA_ADDR) {
		addr = (long) tmp_floppy_area;
		if (command == FD_WRITE)
			copy_buffer(CURRENT->buffer, tmp_floppy_area);
	}
	cli();
	disable_dma(FLOPPY_DMA);

	//clear_dma_ff(FLOPPY_DMA);
	set_dma_mode(FLOPPY_DMA, (command == FD_READ)? DMA_MODE_READ : DMA_MODE_WRITE);
	set_dma_addr(FLOPPY_DMA, addr);
	set_dma_count(FLOPPY_DMA, count);
	enable_dma(FLOPPY_DMA);
	sti();
}

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);
	}
}

static int bfin_lq035_fb_open(struct fb_info *info, int user)
{
	unsigned long flags;

	spin_lock_irqsave(&bfin_lq035_lock, flags);
	lq035_open_cnt++;
	spin_unlock_irqrestore(&bfin_lq035_lock, flags);

	if (lq035_open_cnt <= 1) {
		bfin_write_PPI_CONTROL(0);
		SSYNC();

		set_vcomm();
		config_dma();
		config_ppi();

		/* start dma */
		enable_dma(CH_PPI);
		SSYNC();
		bfin_write_PPI_CONTROL(bfin_read_PPI_CONTROL() | PORT_EN);
		SSYNC();

		if (!t_conf_done) {
			config_timers();
			start_timers();
		}
		/* gpio_set_value(MOD,1); */
	}

	return 0;
}

/* 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);
}

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 bfin_sir_dma_tx_chars(struct net_device *dev)
{
	struct bfin_sir_self *self = netdev_priv(dev);
	struct bfin_sir_port *port = self->sir_port;

	if (!port->tx_done)
		return;
	port->tx_done = 0;

	if (self->tx_buff.len == 0) {
		self->stats.tx_packets++;
		if (self->newspeed) {
			bfin_sir_set_speed(port, self->newspeed);
			self->speed = self->newspeed;
			self->newspeed = 0;
		}
		bfin_sir_enable_rx(port);
		port->tx_done = 1;
		netif_wake_queue(dev);
		return;
	}

	blackfin_dcache_flush_range((unsigned long)(self->tx_buff.data),
		(unsigned long)(self->tx_buff.data+self->tx_buff.len));
	set_dma_config(port->tx_dma_channel,
		set_bfin_dma_config(DIR_READ, DMA_FLOW_STOP,
			INTR_ON_BUF, DIMENSION_LINEAR, DATA_SIZE_8,
			DMA_SYNC_RESTART));
	set_dma_start_addr(port->tx_dma_channel,
		(unsigned long)(self->tx_buff.data));
	set_dma_x_count(port->tx_dma_channel, self->tx_buff.len);
	set_dma_x_modify(port->tx_dma_channel, 1);
	enable_dma(port->tx_dma_channel);
}

static int ppi_start(struct ppi_if *ppi)
{
	const struct ppi_info *info = ppi->info;

	/* enable DMA */
	enable_dma(info->dma_ch);

	/* enable PPI */
	ppi->ppi_control |= PORT_EN;
	switch (info->type) {
	case PPI_TYPE_PPI:
	{
		struct bfin_ppi_regs *reg = info->base;
		bfin_write16(&reg->control, ppi->ppi_control);
		break;
	}
	case PPI_TYPE_EPPI:
	{
		struct bfin_eppi_regs *reg = info->base;
		bfin_write32(&reg->control, ppi->ppi_control);
		break;
	}
	case PPI_TYPE_EPPI3:
	{
		struct bfin_eppi3_regs *reg = info->base;
		bfin_write32(&reg->ctl, ppi->ppi_control);
		break;
	}
	default:
		return -EINVAL;
	}

	SSYNC();
	return 0;
}

/* Prototype: fasdmatype_t powertecscsi_dma_setup(host, SCpnt, direction, min_type)
 * Purpose  : initialises DMA/PIO
 * Params   : host      - host
 *	      SCpnt     - command
 *	      direction - DMA on to/off of card
 *	      min_type  - minimum DMA support that we must have for this transfer
 * Returns  : type of transfer to be performed
 */
static fasdmatype_t
powertecscsi_dma_setup(struct Scsi_Host *host, Scsi_Pointer *SCp,
		       fasdmadir_t direction, fasdmatype_t min_type)
{
	struct powertec_info *info = (struct powertec_info *)host->hostdata;
	int dmach = host->dma_channel;

	if (info->info.ifcfg.capabilities & FASCAP_DMA &&
	    min_type == fasdma_real_all) {
		int bufs, map_dir, dma_dir;

		bufs = copy_SCp_to_sg(&info->sg[0], SCp, NR_SG);

		if (direction == DMA_OUT)
			map_dir = PCI_DMA_TODEVICE,
			dma_dir = DMA_MODE_WRITE;
		else
			map_dir = PCI_DMA_FROMDEVICE,
			dma_dir = DMA_MODE_READ;

		pci_map_sg(NULL, info->sg, bufs, map_dir);

		disable_dma(dmach);
		set_dma_sg(dmach, info->sg, bufs);
		set_dma_mode(dmach, dma_dir);
		enable_dma(dmach);
		return fasdma_real_all;
	}

	/*
	 * If we're not doing DMA,
	 *  we'll do slow PIO
	 */
	return fasdma_pio;
}

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 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 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;
}

static int bfin_sir_startup(struct bfin_sir_port *port, struct net_device *dev)
{
#ifdef CONFIG_SIR_BFIN_DMA
	dma_addr_t dma_handle;
#endif /* CONFIG_SIR_BFIN_DMA */

	if (request_dma(port->rx_dma_channel, "BFIN_UART_RX") < 0) {
		dev_warn(&dev->dev, "Unable to attach SIR RX DMA channel\n");
		return -EBUSY;
	}

	if (request_dma(port->tx_dma_channel, "BFIN_UART_TX") < 0) {
		dev_warn(&dev->dev, "Unable to attach SIR TX DMA channel\n");
		free_dma(port->rx_dma_channel);
		return -EBUSY;
	}

#ifdef CONFIG_SIR_BFIN_DMA

	set_dma_callback(port->rx_dma_channel, bfin_sir_dma_rx_int, dev);
	set_dma_callback(port->tx_dma_channel, bfin_sir_dma_tx_int, dev);

	port->rx_dma_buf.buf = dma_alloc_coherent(NULL, PAGE_SIZE,
						  &dma_handle, GFP_DMA);
	port->rx_dma_buf.head = 0;
	port->rx_dma_buf.tail = 0;
	port->rx_dma_nrows = 0;

	set_dma_config(port->rx_dma_channel,
				set_bfin_dma_config(DIR_WRITE, DMA_FLOW_AUTO,
									INTR_ON_ROW, DIMENSION_2D,
									DATA_SIZE_8, DMA_SYNC_RESTART));
	set_dma_x_count(port->rx_dma_channel, DMA_SIR_RX_XCNT);
	set_dma_x_modify(port->rx_dma_channel, 1);
	set_dma_y_count(port->rx_dma_channel, DMA_SIR_RX_YCNT);
	set_dma_y_modify(port->rx_dma_channel, 1);
	set_dma_start_addr(port->rx_dma_channel, (unsigned long)port->rx_dma_buf.buf);
	enable_dma(port->rx_dma_channel);

	port->rx_dma_timer.data = (unsigned long)(dev);
	port->rx_dma_timer.function = (void *)bfin_sir_rx_dma_timeout;

#else

	if (request_irq(port->irq, bfin_sir_rx_int, 0, "BFIN_SIR_RX", dev)) {
		dev_warn(&dev->dev, "Unable to attach SIR RX interrupt\n");
		return -EBUSY;
	}

	if (request_irq(port->irq+1, bfin_sir_tx_int, 0, "BFIN_SIR_TX", dev)) {
		dev_warn(&dev->dev, "Unable to attach SIR TX interrupt\n");
		free_irq(port->irq, dev);
		return -EBUSY;
	}
#endif

	return 0;
}

void sport_rx_start(struct sport_device *sport)
{
	set_dma_next_desc_addr(sport->rx_dma_chan, sport->rx_desc);
	set_dma_config(sport->rx_dma_chan, DMAFLOW_LIST | DI_EN | WNR
			| compute_wdsize(sport->wdsize) | NDSIZE_6);
	enable_dma(sport->rx_dma_chan);
	sport->rx_regs->spctl |= SPORT_CTL_SPENPRI;
	SSYNC();
}

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;
}

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;
}