int s3c_dma_started(struct s3c2410_dma_chan *chan)
{
	unsigned long flags;

	local_irq_save(flags);

	dbg_showchan(chan);

	/* if we've only loaded one buffer onto the channel, then chec
	 * to see if we have another, and if so, try and load it so when
	 * the first buffer is finished, the new one will be loaded onto
	 * the channel */

	if (chan->next != NULL) {
		if (chan->load_state == S3C_DMALOAD_1LOADED) {

			if (s3c_dma_waitforload(chan, __LINE__) == 0) {
				pr_debug("%s: buff not yet loaded, no more todo\n",
					 __FUNCTION__);
			} else {
				chan->load_state = S3C_DMALOAD_1RUNNING;
				s3c_dma_loadbuffer(chan, chan->next);
			}

		} else if (chan->load_state == S3C_DMALOAD_1RUNNING) {
			s3c_dma_loadbuffer(chan, chan->next);
		}
	}

	local_irq_restore(flags);

	return 0;

}

static int s3c2410_dma_dostop(s3c2410_dma_chan_t *chan)
{
	unsigned long tmp;
	unsigned long flags;

	pr_debug("%s:\n", __FUNCTION__);

	dbg_showchan(chan);

	local_irq_save(flags);

	s3c2410_dma_call_op(chan,  S3C2410_DMAOP_STOP);

	tmp = dma_rdreg(chan, S3C2410_DMA_DMASKTRIG);
	tmp |= S3C2410_DMASKTRIG_STOP;
	dma_wrreg(chan, S3C2410_DMA_DMASKTRIG, tmp);

#if 0
	/* should also clear interrupts, according to WinCE BSP */
	tmp = dma_rdreg(chan, S3C2410_DMA_DCON);
	tmp |= S3C2410_DCON_NORELOAD;
	dma_wrreg(chan, S3C2410_DMA_DCON, tmp);
#endif

	chan->state      = S3C2410_DMA_IDLE;
	chan->load_state = S3C2410_DMALOAD_NONE;

	local_irq_restore(flags);

	return 0;
}

int s3c2410_dma_request(unsigned int channel,
			struct s3c2410_dma_client *client,
			void *dev)
{
	struct s3c2410_dma_chan *chan;
	unsigned long flags;

	pr_debug("dma%d: s3c2410_request_dma: client=%s, dev=%p\n",
		 channel, client->name, dev);

	local_irq_save(flags);

	chan = s3c64xx_dma_map_channel(channel);
	if (chan == NULL) {
		local_irq_restore(flags);
		return -EBUSY;
	}

	dbg_showchan(chan);

	chan->client = client;
	chan->in_use = 1;
	chan->peripheral = channel;

	local_irq_restore(flags);

	/* need to setup */

	pr_debug("%s: channel initialised, %p\n", __func__, chan);

	return chan->number | DMACH_LOW_LEVEL;
}

static int s3c64xx_dma_stop(struct s3c2410_dma_chan *chan)
{
	u32 config;
	int timeout;

	pr_debug("%s: stopping channel\n", __func__);

	dbg_showchan(chan);

	config = readl(chan->regs + PL080S_CH_CONFIG);
	config |= PL080_CONFIG_HALT;
	writel(config, chan->regs + PL080S_CH_CONFIG);

	timeout = 1000;
	do {
		config = readl(chan->regs + PL080S_CH_CONFIG);
		pr_debug("%s: %d - config %08x\n", __func__, timeout, config);
		if (config & PL080_CONFIG_ACTIVE)
			udelay(10);
		else
			break;
		} while (--timeout > 0);

	if (config & PL080_CONFIG_ACTIVE) {
		printk(KERN_ERR "%s: channel still active\n", __func__);
		return -EFAULT;
	}

	config = readl(chan->regs + PL080S_CH_CONFIG);
	config &= ~PL080_CONFIG_ENABLE;
	writel(config, chan->regs + PL080S_CH_CONFIG);

	return 0;
}

static int s3c64xx_dma_flush(struct s3c2410_dma_chan *chan)
{
	struct s3c64xx_dma_buff *buff, *next;
	u32 config;

	dbg_showchan(chan);

	pr_debug("%s: flushing channel\n", __func__);

	config = readl(chan->regs + PL080S_CH_CONFIG);
	config &= ~PL080_CONFIG_ENABLE;
	writel(config, chan->regs + PL080S_CH_CONFIG);

	/* dump all the buffers associated with this channel */

	for (buff = chan->curr; buff != NULL; buff = next) {
		next = buff->next;
		pr_debug("%s: buff %p (next %p)\n", __func__, buff, buff->next);

		s3c64xx_dma_bufffdone(chan, buff, S3C2410_RES_ABORT);
		s3c64xx_dma_freebuff(buff);
	}

	chan->curr = chan->next = chan->end = NULL;

	return 0;
}

static int s3c2410_dma_dostop(struct s3c2410_dma_chan *chan)
{
	unsigned long flags;
	unsigned long tmp;

	pr_debug("%s:\n", __func__);

	dbg_showchan(chan);

	local_irq_save(flags);

	s3c2410_dma_call_op(chan,  S3C2410_DMAOP_STOP);

	tmp = dma_rdreg(chan, S3C2410_DMA_DMASKTRIG);
	tmp |= S3C2410_DMASKTRIG_STOP;
	//tmp &= ~S3C2410_DMASKTRIG_ON;
	dma_wrreg(chan, S3C2410_DMA_DMASKTRIG, tmp);

#if 0
	/* should also clear interrupts, according to WinCE BSP */
	tmp = dma_rdreg(chan, S3C2410_DMA_DCON);
	tmp |= S3C2410_DCON_NORELOAD;
	dma_wrreg(chan, S3C2410_DMA_DCON, tmp);
#endif

	/* should stop do this, or should we wait for flush? */
	chan->state      = S3C2410_DMA_IDLE;
	chan->load_state = S3C2410_DMALOAD_NONE;

	local_irq_restore(flags);

	return 0;
}

static int s3c_dma_dostop(struct s3c2410_dma_chan *chan) 
{
	unsigned long tmp;
	unsigned long flags;

	pr_debug("%s: DMA Channel No : %d\n", __FUNCTION__, chan->number);

	dbg_showchan(chan);

	local_irq_save(flags);

    //Commenting out this function call(as its causing freeze) and even without this it adheres to  
    //ARM Primecell 080's disabling a DMA channel and losing data in the FIFO method 
	//s3c_dma_flush_fifo(chan);
	
	s3c_dma_call_op(chan, S3C2410_DMAOP_STOP);

	tmp = dma_rdreg(chan, S3C_DMAC_CxCONFIGURATION);
	
	tmp &= ~S3C_DMACONFIG_CHANNEL_ENABLE;
	dma_wrreg(chan, S3C_DMAC_CxCONFIGURATION, tmp);
	
	pr_debug("%s: S3C_DMAC_CxCONFIGURATION : %08x\n", __FUNCTION__, tmp);

	chan->state = S3C_DMA_IDLE;
	chan->load_state = S3C_DMALOAD_NONE;

	local_irq_restore(flags);

	return 0;
}

static int s3c64xx_dma_start(struct s3c2410_dma_chan *chan)
{
	struct s3c64xx_dmac *dmac = chan->dmac;
	u32 config;
	u32 bit = chan->bit;

	dbg_showchan(chan);

	pr_debug("%s: clearing interrupts\n", __func__);

	/* clear interrupts */
	writel(bit, dmac->regs + PL080_TC_CLEAR);
	writel(bit, dmac->regs + PL080_ERR_CLEAR);

	pr_debug("%s: starting channel\n", __func__);

	config = readl(chan->regs + PL080S_CH_CONFIG);
	config |= PL080_CONFIG_ENABLE;
	config &= ~PL080_CONFIG_HALT;

	pr_debug("%s: writing config %08x\n", __func__, config);
	writel(config, chan->regs + PL080S_CH_CONFIG);

	return 0;
}

static int s3c_dma_dostop(struct s3c2410_dma_chan *chan) 
{
	unsigned long tmp;
	unsigned long flags;

	pr_debug("%s: DMA Channel No : %d\n", __FUNCTION__, chan->number);

	dbg_showchan(chan);

	local_irq_save(flags);

	s3c_dma_flush_fifo(chan);
	
	s3c_dma_call_op(chan, S3C2410_DMAOP_STOP);

	tmp = dma_rdreg(chan, S3C_DMAC_CxCONFIGURATION);
	
	tmp &= ~S3C_DMACONFIG_CHANNEL_ENABLE;
	dma_wrreg(chan, S3C_DMAC_CxCONFIGURATION, tmp);
	
	pr_debug("%s: S3C_DMAC_CxCONFIGURATION : %08x\n", __FUNCTION__, tmp);

	chan->state = S3C_DMA_IDLE;
	chan->load_state = S3C_DMALOAD_NONE;

	local_irq_restore(flags);

	return 0;
}

int s3c2410_dma_request(unsigned int channel,
                        struct s3c2410_dma_client *client,
                        void *dev)
{
    struct s3c2410_dma_chan *chan;
    unsigned long flags;
    int err;

    pr_debug("dma%d: s3c2410_request_dma: client=%s, dev=%p\n",
             channel, client->name, dev);

    local_irq_save(flags);

    chan = s3c2410_dma_map_channel(channel);
    if (chan == NULL) {
        local_irq_restore(flags);
        return -EBUSY;
    }

    dbg_showchan(chan);

    chan->client = client;
    chan->in_use = 1;

    if (!chan->irq_claimed) {
        pr_debug("dma%d: %s : requesting irq %d\n",
                 channel, __func__, chan->irq);

        chan->irq_claimed = 1;
        local_irq_restore(flags);

        err = request_irq(chan->irq, s3c2410_dma_irq, IRQF_DISABLED,
                          client->name, (void *)chan);

        local_irq_save(flags);

        if (err) {
            chan->in_use = 0;
            chan->irq_claimed = 0;
            local_irq_restore(flags);

            printk(KERN_ERR "%s: cannot get IRQ %d for DMA %d\n",
                   client->name, chan->irq, chan->number);
            return err;
        }

        chan->irq_enabled = 1;
    }

    local_irq_restore(flags);

    /* need to setup */

    pr_debug("%s: channel initialised, %p\n", __func__, chan);

    return chan->number | DMACH_LOW_LEVEL;
}

int s3c2410_dma_request(unsigned int channel, s3c2410_dma_client_t *client,
			void *dev)
{
	s3c2410_dma_chan_t *chan = &s3c2410_chans[channel];
	unsigned long flags;
	int err;

	pr_debug("dma%d: s3c2410_request_dma: client=%s, dev=%p\n",
		 channel, client->name, dev);

	check_channel(channel);

	local_irq_save(flags);

	dbg_showchan(chan);

	if (chan->in_use) {
		if (client != chan->client) {
			printk(KERN_ERR "dma%d: already in use\n", channel);
			local_irq_restore(flags);
			return -EBUSY;
		} else {
			printk(KERN_ERR "dma%d: client already has channel\n", channel);
		}
	}

	chan->client = client;
	chan->in_use = 1;

	if (!chan->irq_claimed) {
		pr_debug("dma%d: %s : requesting irq %d\n",
			 channel, __FUNCTION__, chan->irq);

		err = request_irq(chan->irq, s3c2410_dma_irq, SA_INTERRUPT,
				  client->name, (void *)chan);

		if (err) {
			chan->in_use = 0;
			local_irq_restore(flags);

			printk(KERN_ERR "%s: cannot get IRQ %d for DMA %d\n",
			       client->name, chan->irq, chan->number);
			return err;
		}

		chan->irq_claimed = 1;
		chan->irq_enabled = 1;
	}

	local_irq_restore(flags);

	/* need to setup */

	pr_debug("%s: channel initialised, %p\n", __FUNCTION__, chan);

	return 0;
}

static int s3c2410_dma_flush(struct s3c2410_dma_chan *chan)
{
    struct s3c2410_dma_buf *buf, *next;
    unsigned long flags;

    pr_debug("%s: chan %p (%d)\n", __func__, chan, chan->number);

    dbg_showchan(chan);

    local_irq_save(flags);

    if (chan->state != S3C2410_DMA_IDLE) {
        pr_debug("%s: stopping channel...\n", __func__ );
        s3c2410_dma_ctrl(chan->number, S3C2410_DMAOP_STOP);
    }

    buf = chan->curr;
    if (buf == NULL)
        buf = chan->next;

    chan->curr = chan->next = chan->end = NULL;

    if (buf != NULL) {
        for ( ; buf != NULL; buf = next) {
            next = buf->next;

            pr_debug("%s: free buffer %p, next %p\n",
                     __func__, buf, buf->next);

            s3c2410_dma_buffdone(chan, buf, S3C2410_RES_ABORT);
            s3c2410_dma_freebuf(buf);
        }
    }

    dbg_showregs(chan);

    s3c2410_dma_waitforstop(chan);

#if 0
    /* should also clear interrupts, according to WinCE BSP */
    {
        unsigned long tmp;

        tmp = dma_rdreg(chan, S3C2410_DMA_DCON);
        tmp |= S3C2410_DCON_NORELOAD;
        dma_wrreg(chan, S3C2410_DMA_DCON, tmp);
    }
#endif

    dbg_showregs(chan);

    local_irq_restore(flags);

    return 0;
}

static int s3c2410_dma_flush(struct s3c2410_dma_chan *chan)
{
	struct s3c2410_dma_buf *buf, *next;
	unsigned long flags;

	pr_debug("%s: chan %p (%d)\n", __func__, chan, chan->number);

	dbg_showchan(chan);

	local_irq_save(flags);

	if (chan->state != S3C2410_DMA_IDLE) {
		pr_debug("%s: stopping channel...\n", __func__ );
		s3c2410_dma_ctrl(chan->number, S3C2410_DMAOP_STOP);
	}

	buf = chan->curr;
	if (buf == NULL)
		buf = chan->next;

	chan->curr = chan->next = chan->end = NULL;

	if (buf != NULL) {
		for ( ; buf != NULL; buf = next) {
			next = buf->next;

			pr_debug("%s: free buffer %p, next %p\n",
			       __func__, buf, buf->next);

			s3c2410_dma_buffdone(chan, buf, S3C2410_RES_ABORT);
			s3c2410_dma_freebuf(buf);
		}
	}

	dbg_showregs(chan);

	s3c2410_dma_waitforstop(chan);


	dbg_showregs(chan);

	local_irq_restore(flags);

	return 0;
}

static int s3c_dma_dostop(struct s3c2410_dma_chan *chan)
{
	unsigned long flags;

	pr_debug("%s: DMA Channel No : %d\n", __FUNCTION__, chan->number);

	dbg_showchan(chan);

	local_irq_save(flags);

	s3c_dma_call_op(chan, S3C2410_DMAOP_STOP);

	stop_DMA_channel(dma_regaddr(chan->dma_con, S3C_DMAC_DBGSTATUS), chan->number);

	chan->state = S3C_DMA_IDLE;
	chan->load_state = S3C_DMALOAD_NONE;

	local_irq_restore(flags);

	return 0;
}

static irqreturn_t
s3c2410_dma_irq(int irq, void *devpw)
{
    struct s3c2410_dma_chan *chan = (struct s3c2410_dma_chan *)devpw;
    struct s3c2410_dma_buf  *buf;

    buf = chan->curr;

    dbg_showchan(chan);

    /* modify the channel state */

    switch (chan->load_state) {
    case S3C2410_DMALOAD_1RUNNING:
        /* TODO - if we are running only one buffer, we probably
         * want to reload here, and then worry about the buffer
         * callback */

        chan->load_state = S3C2410_DMALOAD_NONE;
        break;

    case S3C2410_DMALOAD_1LOADED:
        /* iirc, we should go back to NONE loaded here, we
         * had a buffer, and it was never verified as being
         * loaded.
         */

        chan->load_state = S3C2410_DMALOAD_NONE;
        break;

    case S3C2410_DMALOAD_1LOADED_1RUNNING:
        /* we'll worry about checking to see if another buffer is
         * ready after we've called back the owner. This should
         * ensure we do not wait around too long for the DMA
         * engine to start the next transfer
         */

        chan->load_state = S3C2410_DMALOAD_1LOADED;
        break;

    case S3C2410_DMALOAD_NONE:
        printk(KERN_ERR "dma%d: IRQ with no loaded buffer?\n",
               chan->number);
        break;

    default:
        printk(KERN_ERR "dma%d: IRQ in invalid load_state %d\n",
               chan->number, chan->load_state);
        break;
    }

    if (buf != NULL) {
        /* update the chain to make sure that if we load any more
         * buffers when we call the callback function, things should
         * work properly */

        chan->curr = buf->next;
        buf->next  = NULL;

        if (buf->magic != BUF_MAGIC) {
            printk(KERN_ERR "dma%d: %s: buf %p incorrect magic\n",
                   chan->number, __func__, buf);
            return IRQ_HANDLED;
        }

        s3c2410_dma_buffdone(chan, buf, S3C2410_RES_OK);

        /* free resouces */
        s3c2410_dma_freebuf(buf);
    } else {
    }

    /* only reload if the channel is still running... our buffer done
     * routine may have altered the state by requesting the dma channel
     * to stop or shutdown... */

    /* todo: check that when the channel is shut-down from inside this
     * function, we cope with unsetting reload, etc */

    if (chan->next != NULL && chan->state != S3C2410_DMA_IDLE) {
        unsigned long flags;

        switch (chan->load_state) {
        case S3C2410_DMALOAD_1RUNNING:
            /* don't need to do anything for this state */
            break;

        case S3C2410_DMALOAD_NONE:
            /* can load buffer immediately */
            break;

        case S3C2410_DMALOAD_1LOADED:
            if (s3c2410_dma_waitforload(chan, __LINE__) == 0) {
                /* flag error? */
                printk(KERN_ERR "dma%d: timeout waiting for load (%s)\n",
                       chan->number, __func__);
                return IRQ_HANDLED;
            }

            break;
//.........这里部分代码省略.........

int s3c2410_dma_enqueue(unsigned int channel, void *id,
                        dma_addr_t data, int size)
{
    struct s3c2410_dma_chan *chan = lookup_dma_channel(channel);
    struct s3c2410_dma_buf *buf;
    unsigned long flags;

    if (chan == NULL)
        return -EINVAL;

    pr_debug("%s: id=%p, data=%08x, size=%d\n",
             __func__, id, (unsigned int)data, size);

    buf = kmem_cache_alloc(dma_kmem, GFP_ATOMIC);
    if (buf == NULL) {
        pr_debug("%s: out of memory (%ld alloc)\n",
                 __func__, (long)sizeof(*buf));
        return -ENOMEM;
    }

    //pr_debug("%s: new buffer %p\n", __func__, buf);
    //dbg_showchan(chan);

    buf->next  = NULL;
    buf->data  = buf->ptr = data;
    buf->size  = size;
    buf->id    = id;
    buf->magic = BUF_MAGIC;

    local_irq_save(flags);

    if (chan->curr == NULL) {
        /* we've got nothing loaded... */
        pr_debug("%s: buffer %p queued onto empty channel\n",
                 __func__, buf);

        chan->curr = buf;
        chan->end  = buf;
        chan->next = NULL;
    } else {
        pr_debug("dma%d: %s: buffer %p queued onto non-empty channel\n",
                 chan->number, __func__, buf);

        if (chan->end == NULL)
            pr_debug("dma%d: %s: %p not empty, and chan->end==NULL?\n",
                     chan->number, __func__, chan);

        chan->end->next = buf;
        chan->end = buf;
    }

    /* if necessary, update the next buffer field */
    if (chan->next == NULL)
        chan->next = buf;

    /* check to see if we can load a buffer */
    if (chan->state == S3C2410_DMA_RUNNING) {
        if (chan->load_state == S3C2410_DMALOAD_1LOADED && 1) {
            if (s3c2410_dma_waitforload(chan, __LINE__) == 0) {
                printk(KERN_ERR "dma%d: loadbuffer:"
                       "timeout loading buffer\n",
                       chan->number);
                dbg_showchan(chan);
                local_irq_restore(flags);
                return -EINVAL;
            }
        }

        while (s3c2410_dma_canload(chan) && chan->next != NULL) {
            s3c2410_dma_loadbuffer(chan, chan->next);
        }
    } else if (chan->state == S3C2410_DMA_IDLE) {
        if (chan->flags & S3C2410_DMAF_AUTOSTART) {
            s3c2410_dma_ctrl(chan->number | DMACH_LOW_LEVEL,
                             S3C2410_DMAOP_START);
        }
    }

    local_irq_restore(flags);
    return 0;
}

static int s3c2410_dma_start(struct s3c2410_dma_chan *chan)
{
    unsigned long tmp;
    unsigned long flags;

    pr_debug("s3c2410_start_dma: channel=%d\n", chan->number);

    local_irq_save(flags);

    if (chan->state == S3C2410_DMA_RUNNING) {
        pr_debug("s3c2410_start_dma: already running (%d)\n", chan->state);
        local_irq_restore(flags);
        return 0;
    }

    chan->state = S3C2410_DMA_RUNNING;

    /* check wether there is anything to load, and if not, see
     * if we can find anything to load
     */

    if (chan->load_state == S3C2410_DMALOAD_NONE) {
        if (chan->next == NULL) {
            printk(KERN_ERR "dma%d: channel has nothing loaded\n",
                   chan->number);
            chan->state = S3C2410_DMA_IDLE;
            local_irq_restore(flags);
            return -EINVAL;
        }

        s3c2410_dma_loadbuffer(chan, chan->next);
    }

    dbg_showchan(chan);

    /* enable the channel */

    if (!chan->irq_enabled) {
        enable_irq(chan->irq);
        chan->irq_enabled = 1;
    }

    /* start the channel going */

    tmp = dma_rdreg(chan, S3C2410_DMA_DMASKTRIG);
    tmp &= ~S3C2410_DMASKTRIG_STOP;
    tmp |= S3C2410_DMASKTRIG_ON;
    dma_wrreg(chan, S3C2410_DMA_DMASKTRIG, tmp);

    pr_debug("dma%d: %08lx to DMASKTRIG\n", chan->number, tmp);

#if 0
    /* the dma buffer loads should take care of clearing the AUTO
     * reloading feature */
    tmp = dma_rdreg(chan, S3C2410_DMA_DCON);
    tmp &= ~S3C2410_DCON_NORELOAD;
    dma_wrreg(chan, S3C2410_DMA_DCON, tmp);
#endif

    s3c2410_dma_call_op(chan, S3C2410_DMAOP_START);

    dbg_showchan(chan);

    /* if we've only loaded one buffer onto the channel, then chec
     * to see if we have another, and if so, try and load it so when
     * the first buffer is finished, the new one will be loaded onto
     * the channel */

    if (chan->next != NULL) {
        if (chan->load_state == S3C2410_DMALOAD_1LOADED) {

            if (s3c2410_dma_waitforload(chan, __LINE__) == 0) {
                pr_debug("%s: buff not yet loaded, no more todo\n",
                         __func__);
            } else {
                chan->load_state = S3C2410_DMALOAD_1RUNNING;
                s3c2410_dma_loadbuffer(chan, chan->next);
            }

        } else if (chan->load_state == S3C2410_DMALOAD_1RUNNING) {
            s3c2410_dma_loadbuffer(chan, chan->next);
        }
    }


    local_irq_restore(flags);

    return 0;
}

int s3c2410_dma_request(unsigned int channel,
			struct s3c2410_dma_client *client,
			void *dev)
{
	struct s3c2410_dma_chan *chan;
	unsigned long flags;
	int err;

	pr_debug("DMA CH %d: s3c2410_request_dma: client=%s, dev=%p\n",
		 channel, client->name, dev);

	local_irq_save(flags);

	chan = s3c_dma_map_channel(channel);
	if (chan == NULL) {
		local_irq_restore(flags);
		return -EBUSY;
	}

	dbg_showchan(chan);

	chan->client = client;
	chan->in_use = 1;

	chan->dma_con->in_use++;

	if (!chan->irq_claimed) {
		pr_debug("DMA CH %d: %s : requesting irq %d\n",
			 channel, __FUNCTION__, chan->irq);

		chan->irq_claimed = 1;
		local_irq_restore(flags);

		err = request_irq(chan->irq, s3c_dma_irq, IRQF_SHARED | IRQF_DISABLED,
				  client->name, (void *) chan->dma_con);

		local_irq_save(flags);

		if (err) {
			chan->in_use = 0;
			chan->irq_claimed = 0;
			chan->dma_con->in_use--;
			local_irq_restore(flags);

			printk(KERN_ERR "%s: cannot get IRQ %d for DMA %d\n",
			       client->name, chan->irq, chan->number);
			return err;
		}

		chan->irq_enabled = 1;

		/* enable the main dma.. this can be disabled
		 * when main channel use count is 0 */
		s3c_enable_dmac(chan->dma_con->number);
	}

	s3c_clear_interrupts(chan->dma_con->number, chan->number);
	local_irq_restore(flags);

	/* need to setup */

	pr_debug("%s: channel initialised, %p, number:%d, index:%d\n", __FUNCTION__, chan, chan->number, chan->index);

	return 0;
}

static irqreturn_t s3c_dma_irq(int irq, void *devpw)
{
	unsigned int channel = 0, dcon_num, i;
	unsigned long tmp;
	s3c_dma_controller_t *dma_controller = (s3c_dma_controller_t *) devpw;

	struct s3c2410_dma_chan *chan=NULL;
	struct s3c_dma_buf *buf;

	dcon_num = dma_controller->number;
	tmp = dma_rdreg(dma_controller, S3C_DMAC_INTSTATUS);
	pr_debug("# s3c_dma_irq: IRQ status : 0x%x\n", tmp);

	if (tmp == 0)
		return IRQ_HANDLED;

	for (i = 0; i < S3C_CHANNELS_PER_DMA; i++) {
		if (tmp & 0x01) {

			pr_debug("# DMAC %d: requestor %d\n", dcon_num, i);

			channel = i;
			chan = &s3c_dma_chans[channel + dcon_num * S3C_CHANNELS_PER_DMA];
			pr_debug("# DMA CH:%d, index:%d load_state:%d\n", chan->number, chan->index, chan->load_state);

			buf = chan->curr;

			dbg_showchan(chan);

			/* modify the channel state */
			switch (chan->load_state) {
			case S3C_DMALOAD_1RUNNING:
				/* TODO - if we are running only one buffer, we probably
				 * want to reload here, and then worry about the buffer
				 * callback */

				chan->load_state = S3C_DMALOAD_NONE;
				break;

			case S3C_DMALOAD_1LOADED:
				/* iirc, we should go back to NONE loaded here, we
				 * had a buffer, and it was never verified as being
				 * loaded.
				 */

				chan->load_state = S3C_DMALOAD_NONE;
				break;

			case S3C_DMALOAD_1LOADED_1RUNNING:
				/* we'll worry about checking to see if another buffer is
				 * ready after we've called back the owner. This should
				 * ensure we do not wait around too long for the DMA
				 * engine to start the next transfer
				 */

				chan->load_state = S3C_DMALOAD_1LOADED;
				break;

			case S3C_DMALOAD_NONE:
				printk(KERN_ERR "dma%d: IRQ with no loaded buffer?\n",
				       chan->number);
				break;

			default:
				printk(KERN_ERR "dma%d: IRQ in invalid load_state %d\n",
				       chan->number, chan->load_state);
				break;
			}

			if (buf != NULL) {
				/* update the chain to make sure that if we load any more
				 * buffers when we call the callback function, things should
				 * work properly */

				chan->curr = buf->next;
				buf->next = NULL;

				if (buf->magic != BUF_MAGIC) {
					printk(KERN_ERR "dma CH %d: %s: buf %p incorrect magic\n",
					       chan->number, __FUNCTION__, buf);
					goto next_channel;
				}

				s3c_dma_buffdone(chan, buf, S3C2410_RES_OK);

				/* free resouces */
				s3c_dma_freebuf(buf);
			} else {
			}

			/* only reload if the channel is still running... our buffer done
	 		* routine may have altered the state by requesting the dma channel
			* to stop or shutdown... */

			if (chan->next != NULL && chan->state != S3C_DMA_IDLE) {
				unsigned long flags;

				switch (chan->load_state) {
				case S3C_DMALOAD_1RUNNING:
					/* don't need to do anything for this state */
//.........这里部分代码省略.........

/* s3c2410_dma_enqueue
 *
 * queue an given buffer for dma transfer.
 *
 * id         the device driver's id information for this buffer
 * data       the physical address of the buffer data
 * size       the size of the buffer in bytes
 *
 * If the channel is not running, then the flag S3C2410_DMAF_AUTOSTART
 * is checked, and if set, the channel is started. If this flag isn't set,
 * then an error will be returned.
 *
 * It is possible to queue more than one DMA buffer onto a channel at
 * once, and the code will deal with the re-loading of the next buffer
 * when necessary.
 */
int s3c2410_dma_enqueue(unsigned int channel, void *id,
			dma_addr_t data, int size)
{
	struct s3c2410_dma_chan *chan = lookup_dma_channel(channel);
	struct s3c_dma_buf *buf;
	unsigned long flags;

	pr_debug("%s: id=%p, data=%08x, size=%d\n", __FUNCTION__, id, (unsigned int) data, size);

	buf = kmem_cache_alloc(dma_kmem, GFP_ATOMIC);
	if (buf == NULL) {
		printk(KERN_ERR "dma <%d> no memory for buffer\n", channel);
		return -ENOMEM;
	}

	pr_debug("%s: new buffer %p\n", __FUNCTION__, buf);

	buf->next = NULL;
	buf->data = buf->ptr = data;
	buf->size = size;
	buf->id = id;
	buf->magic = BUF_MAGIC;

	local_irq_save(flags);

	buf->mcptr_cpu = dma_alloc_coherent(NULL, SIZE_OF_MICRO_CODES, &buf->mcptr, GFP_ATOMIC);

	if (buf->mcptr_cpu == NULL) {
		printk(KERN_ERR "%s: failed to allocate memory for micro codes\n", __FUNCTION__);
		return -ENOMEM;
	}

	if (chan->curr == NULL) {
		/* we've got nothing loaded... */
		pr_debug("%s: buffer %p queued onto empty channel\n", __FUNCTION__, buf);

		chan->curr = buf;
		chan->end = buf;
		chan->next = NULL;
	} else {
		pr_debug("dma CH %d: %s: buffer %p queued onto non-empty channel\n",
			 chan->number, __FUNCTION__, buf);

		if (chan->end == NULL)   /* In case of flushing */
			pr_debug("dma CH %d: %s: %p not empty, and chan->end==NULL?\n",
				 chan->number, __FUNCTION__, chan);
		else {
			chan->end->next = buf;
			chan->end = buf;
		}
	}

	/* if necessary, update the next buffer field */
	if (chan->next == NULL)
		chan->next = buf;

	/* check to see if we can load a buffer */
	if (chan->state == S3C_DMA_RUNNING) {
		if (chan->load_state == S3C_DMALOAD_1LOADED && 1) {
			if (s3c_dma_waitforload(chan, __LINE__) == 0) {
				printk(KERN_ERR "dma CH %d: loadbuffer:"
				       "timeout loading buffer\n", chan->number);
				dbg_showchan(chan);
				local_irq_restore(flags);
				return -EINVAL;
			}
		}

	} else if (chan->state == S3C_DMA_IDLE) {
		if (chan->flags & S3C2410_DMAF_AUTOSTART) {
			s3c2410_dma_ctrl(channel, S3C2410_DMAOP_START);
		} else {
			pr_debug("loading onto stopped channel\n");
		}
	}

	local_irq_restore(flags);
	return 0;
}