dma.c

本驱动程序在linux2.6.17中测试通过。yangxing msn:[e-mail] 希望对SPI操作的朋友有所帮助。 一、工作方式： 从设备：SPI为MASTE

		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, __FUNCTION__, buf);
			return IRQ_HANDLED;
		}

		s3c2410_dma_buffdone(chan, buf, S3C2410_RES_OK);

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

	if (chan->next != NULL) {
		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\n",
				       chan->number);
				return IRQ_HANDLED;
			}

			break;

		case S3C2410_DMALOAD_1LOADED_1RUNNING:
			goto no_load;

		default:
			printk(KERN_ERR "dma%d: unknown load_state in irq, %d\n",
			       chan->number, chan->load_state);
			return IRQ_HANDLED;
		}

		local_irq_save(flags);
		s3c2410_dma_loadbuffer(chan, chan->next);
		local_irq_restore(flags);
	} else {
		s3c2410_dma_lastxfer(chan);

		/* see if we can stop this channel.. */
		if (chan->load_state == S3C2410_DMALOAD_NONE) {
			pr_debug("dma%d: end of transfer, stopping channel (%ld)\n",
				 chan->number, jiffies);
			s3c2410_dma_ctrl(chan->number, S3C2410_DMAOP_STOP);
		}
	}

 no_load:
	return IRQ_HANDLED;
}



/* s3c2410_request_dma
 *
 * get control of an dma channel
*/

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;
}

EXPORT_SYMBOL(s3c2410_dma_request);

/* s3c2410_dma_free
 *
 * release the given channel back to the system, will stop and flush
 * any outstanding transfers, and ensure the channel is ready for the
 * next claimant.
 *
 * Note, although a warning is currently printed if the freeing client
 * info is not the same as the registrant's client info, the free is still
 * allowed to go through.
*/

int s3c2410_dma_free(dmach_t channel, s3c2410_dma_client_t *client)
{
	s3c2410_dma_chan_t *chan = &s3c2410_chans[channel];
	unsigned long flags;

	check_channel(channel);

	local_irq_save(flags);


	if (chan->client != client) {
		printk(KERN_WARNING "dma%d: possible free from different client (channel %p, passed %p)\n",
		       channel, chan->client, client);
	}

	/* sort out stopping and freeing the channel */

	if (chan->state != S3C2410_DMA_IDLE) {
		pr_debug("%s: need to stop dma channel %p\n",
		       __FUNCTION__, chan);

		/* possibly flush the channel */
		s3c2410_dma_ctrl(channel, S3C2410_DMAOP_STOP);
	}

	chan->client = NULL;
	chan->in_use = 0;

	if (chan->irq_claimed)
		free_irq(chan->irq, (void *)chan);
	chan->irq_claimed = 0;

	local_irq_restore(flags);

	return 0;
}

EXPORT_SYMBOL(s3c2410_dma_free);

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;
}

/* s3c2410_dma_flush
 *
 * stop the channel, and remove all current and pending transfers
*/

static int s3c2410_dma_flush(s3c2410_dma_chan_t *chan)
{
	s3c2410_dma_buf_t *buf, *next;
	unsigned long flags;

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

	local_irq_save(flags);

	if (chan->state != S3C2410_DMA_IDLE) {
		pr_debug("%s: stopping channel...\n", __FUNCTION__ );
		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",
			       __FUNCTION__, buf, buf->next);

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

	local_irq_restore(flags);

	return 0;
}


int
s3c2410_dma_ctrl(dmach_t channel, s3c2410_chan_op_t op)
{
	s3c2410_dma_chan_t *chan = &s3c2410_chans[channel];

	check_channel(channel);

	switch (op) {
	case S3C2410_DMAOP_START:
		return s3c2410_dma_start(chan);

	case S3C2410_DMAOP_STOP:
		return s3c2410_dma_dostop(chan);

	case S3C2410_DMAOP_PAUSE:
		return -ENOENT;

	case S3C2410_DMAOP_RESUME:
		return -ENOENT;

	case S3C2410_DMAOP_FLUSH:
		return s3c2410_dma_flush(chan);

	case S3C2410_DMAOP_TIMEOUT:
		return 0;

	}

	return -ENOENT;      /* unknown, don't bother */
}

EXPORT_SYMBOL(s3c2410_dma_ctrl);

/* DMA configuration for each channel
 *
 * DISRCC -> source of the DMA (AHB,APB)
 * DISRC  -> source address of the DMA
 * DIDSTC -> destination of the DMA (AHB,APD)
 * DIDST  -> destination address of the DMA
*/

/* s3c2410_dma_config
 *
 * xfersize:     size of unit in bytes (1,2,4)
 * dcon:         base value of the DCONx register
*/

int s3c2410_dma_config(dmach_t channel,
		       int xferunit,
		       int dcon)
{
	s3c2410_dma_chan_t *chan = &s3c2410_chans[channel];

	pr_debug("%s: chan=%d, xfer_unit=%d, dcon=%08x\n",
		 __FUNCTION__, channel, xferunit, dcon);

	check_channel(channel);

	switch (xferunit) {
	case 1:
		dcon |= S3C2410_DCON_BYTE;
		break;

	case 2:
		dcon |= S3C2410_DCON_HALFWORD;
		break;

	case 4:
		dcon |= S3C2410_DCON_WORD;
		break;

	default:
		pr_debug("%s: bad transfer size %d\n", __FUNCTION__, xferunit);
		return -EINVAL;
	}

	dcon |= S3C2410_DCON_HWTRIG;
	dcon |= S3C2410_DCON_INTREQ;

	pr_debug("%s: dcon now %08x\n", __FUNCTION__, dcon);

	chan->dcon = dcon;
	chan->xfer_unit = xferunit;

	return 0;
}

EXPORT_SYMBOL(s3c2410_dma_config);

int s3c2410_dma_setflags(dmach_t channel, unsigned int flags)
{
	s3c2410_dma_chan_t *chan = &s3c2410_chans[channel];

	check_channel(channel);

	pr_debug("%s: chan=%p, flags=%08x\n", __FUNCTION__, chan, flags);

	chan->flags = flags;

	return 0;
}

EXPORT_SYMBOL(s3c2410_dma_setflags);


/* do we need to protect the settings of the fields from
 * irq?
*/

int s3c2410_dma_set_opfn(dmach_t channel, s3c2410_dma_opfn_t rtn)
{
	s3c2410_dma_chan_t *chan = &s3c2410_chans[channel];

	check_channel(channel);

	pr_debug("%s: chan=%p, op rtn=%p\n", __FUNCTION__, chan, rtn);

	chan->op_fn = rtn;

	return 0;
}

EXPORT_SYMBOL(s3c2410_dma_set_opfn);

int s3c2410_dma_set_buffdone_fn(dmach_t channel, s3c2410_dma_cbfn_t rtn)
{
	s3c2410_dma_chan_t *chan = &s3c2410_chans[channel];

	check_channel(channel);

	pr_debug("%s: chan=%p, callback rtn=%p\n", __FUNCTION__, chan, rtn);

	chan->callback_fn = rtn;

	return 0;
}

EXPORT_SYMBOL(s3c2410_dma_set_buffdone_fn);

/* s3c2410_dma_devconfig
 *
 * configure the dma source/destination hardware type and address
 *
 * source:    S3C2410_DMASRC_HW: source is hardware
 *            S3C2410_DMASRC_MEM: source is memory
 *
 * hwcfg:     the value for xxxSTCn register,
 *            bit 0: 0=increment pointer, 1=leave pointer
 *            bit 1: 0=soucre is AHB, 1=soucre is APB
 *
 * devaddr:   physical address of the source
*/

int s3c2410_dma_devconfig(int channel,
			  s3c2410_dmasrc_t source,
			  int hwcfg,
			  unsigned long devaddr)
{
	s3c2410_dma_chan_t *chan = &s3c2410_chans[channel];

	check_channel(channel);

	pr_debug("%s: source=%d, hwcfg=%08x, devaddr=%08lx\n",
		 __FUNCTION__, (int)source, hwcfg, devaddr);

	chan->source = source;
	chan->dev_addr = devaddr;

	switch (source) {
	case S3C2410_DMASRC_HW:
		/* source is hardware */
		pr_debug("%s: hw source, devaddr=%08lx, hwcfg=%d\n",
			 __FUNCTION__, devaddr, hwcfg);
		dma_wrreg(chan, S3C2410_DMA_DISRCC, hwcfg & 3);
		dma_wrreg(chan, S3C2410_DMA_DISRC,  devaddr);
		dma_wrreg(chan, S3C2410_DMA_DIDSTC, (0<<1) | (0<<0));

		chan->addr_reg = dma_regaddr(chan, S3C2410_DMA_DIDST);
		return 0;

	case S3C2410_DMASRC_MEM:
		/* source is memory */
		pr_debug( "%s: mem source, devaddr=%08lx, hwcfg=%d\n",
			  __FUNCTION__, devaddr, hwcfg);
		dma_wrreg(chan, S3C2410_DMA_DISRCC, (0<<1) | (0<<0));
		dma_wrreg(chan, S3C2410_DMA_DIDST,  devaddr);
		dma_wrreg(chan, S3C2410_DMA_DIDSTC, hwcfg & 3);

		chan->addr_reg = dma_regaddr(chan, S3C2410_DMA_DISRC);
		return 0;
	}

	printk(KERN_ERR "dma%d: invalid source type (%d)\n", channel, source);
	return -EINVAL;
}

EXPORT_SYMBOL(s3c2410_dma_devconfig);

/* s3c2410_dma_getposition
 *
 * returns the current transfer points for the dma source and destination
*/

int s3c2410_dma_getposition(dmach_t channel, dma_addr_t *src, dma_addr_t *dst)
{
 	s3c2410_dma_chan_t *chan = &s3c2410_chans[channel];

 	check_channel(channel);

	if (src != NULL)
 		*src = dma_rdreg(chan, S3C2410_DMA_DCSRC);

 	if (dst != NULL)
 		*dst = dma_rdreg(chan, S3C2410_DMA_DCDST);

 	return 0;
}

EXPORT_SYMBOL(s3c2410_dma_getposition);


/* system device class */

#ifdef CONFIG_PM

static int s3c2410_dma_suspend(struct sys_device *dev, pm_message_t state)
{
	s3c2410_dma_chan_t *cp = container_of(dev, s3c2410_dma_chan_t, dev);

	printk(KERN_DEBUG "suspending dma channel %d\n", cp->number);

	if (dma_rdreg(cp, S3C2410_DMA_DMASKTRIG) & S3C2410_DMASKTRIG_ON) {
		/* the dma channel is still working, which is probably
		 * a bad thing to do over suspend/resume. We stop the
		 * channel and assume that the client is either going to
		 * retry after resume, or that it is broken.
		 */

		printk(KERN_INFO "dma: stopping channel %d due to suspend\n",
		       cp->number);

		s3c2410_dma_dostop(cp);
	}

	return 0;
}

static int s3c2410_dma_resume(struct sys_device *dev)
{
	return 0;
}

#else
#define s3c2410_dma_suspend NULL
#define s3c2410_dma_resume  NULL
#endif /* CONFIG_PM */

static struct sysdev_class dma_sysclass = {
	set_kset_name("s3c24xx-dma"),
	.suspend	= s3c2410_dma_suspend,
	.resume		= s3c2410_dma_resume,
};

/* kmem cache implementation */

static void s3c2410_dma_cache_ctor(void *p, kmem_cache_t *c, unsigned long f)
{
	memset(p, 0, sizeof(s3c2410_dma_buf_t));
}


/* initialisation code */

static int __init s3c2410_init_dma(void)
{
	s3c2410_dma_chan_t *cp;
	int channel;
	int ret;

	printk("S3C2410 DMA Driver, (c) 2003-2004 Simtec Electronics\n");

	dma_base = ioremap(S3C24XX_PA_DMA, 0x200);
	if (dma_base == NULL) {
		printk(KERN_ERR "dma failed to remap register block\n");
		return -ENOMEM;
	}

	ret = sysdev_class_register(&dma_sysclass);
	if (ret != 0) {
		printk(KERN_ERR "dma sysclass registration failed\n");
		goto err;
	}

	dma_kmem = kmem_cache_create("dma_desc", sizeof(s3c2410_dma_buf_t), 0,
				     SLAB_HWCACHE_ALIGN,
				     s3c2410_dma_cache_ctor, NULL);

	if (dma_kmem == NULL) {
		printk(KERN_ERR "dma failed to make kmem cache\n");
		ret = -ENOMEM;
		goto err;
	}

	for (channel = 0; channel < S3C2410_DMA_CHANNELS; channel++) {
		cp = &s3c2410_chans[channel];

		memset(cp, 0, sizeof(s3c2410_dma_chan_t));

		/* dma channel irqs are in order.. */
		cp->number = channel;
		cp->irq    = channel + IRQ_DMA0;
		cp->regs   = dma_base + (channel*0x40);

		/* point current stats somewhere */
		cp->stats  = &cp->stats_store;
		cp->stats_store.timeout_shortest = LONG_MAX;

		/* basic channel configuration */

		cp->load_timeout = 1<<18;

		/* register system device */

		cp->dev.cls = &dma_sysclass;
		cp->dev.id  = channel;
		ret = sysdev_register(&cp->dev);

		printk("DMA channel %d at %p, irq %d\n",
		       cp->number, cp->regs, cp->irq);
	}

	return 0;

 err:
	kmem_cache_destroy(dma_kmem);
	iounmap(dma_base);
	dma_base = NULL;
	return ret;
}

__initcall(s3c2410_init_dma);