dma.c

linux 内核源代码

}

/**
 * imx_dma_enable - function to start i.MX DMA channel operation
 * @dma_ch: i.MX DMA channel number
 *
 * The channel has to be allocated by driver through imx_dma_request()
 * or imx_dma_request_by_prio() function.
 * The transfer parameters has to be set to the channel registers through
 * call of the imx_dma_setup_single() or imx_dma_setup_sg() function
 * and registers %BLR(dma_ch), %RSSR(dma_ch) and %CCR(dma_ch) has to
 * be set prior this function call by the channel user.
 */
void imx_dma_enable(imx_dmach_t dma_ch)
{
	struct imx_dma_channel *imxdma = &imx_dma_channels[dma_ch];
	unsigned long flags;

	pr_debug("imxdma%d: imx_dma_enable\n", dma_ch);

	if (!imxdma->name) {
		printk(KERN_CRIT "%s: called for  not allocated channel %d\n",
		       __FUNCTION__, dma_ch);
		return;
	}

	local_irq_save(flags);
	DISR = (1 << dma_ch);
	DIMR &= ~(1 << dma_ch);
	CCR(dma_ch) |= CCR_CEN;
	local_irq_restore(flags);
}

/**
 * imx_dma_disable - stop, finish i.MX DMA channel operatin
 * @dma_ch: i.MX DMA channel number
 */
void imx_dma_disable(imx_dmach_t dma_ch)
{
	unsigned long flags;

	pr_debug("imxdma%d: imx_dma_disable\n", dma_ch);

	local_irq_save(flags);
	DIMR |= (1 << dma_ch);
	CCR(dma_ch) &= ~CCR_CEN;
	DISR = (1 << dma_ch);
	local_irq_restore(flags);
}

/**
 * imx_dma_request - request/allocate specified channel number
 * @dma_ch: i.MX DMA channel number
 * @name: the driver/caller own non-%NULL identification
 */
int imx_dma_request(imx_dmach_t dma_ch, const char *name)
{
	struct imx_dma_channel *imxdma = &imx_dma_channels[dma_ch];
	unsigned long flags;

	/* basic sanity checks */
	if (!name)
		return -EINVAL;

	if (dma_ch >= IMX_DMA_CHANNELS) {
		printk(KERN_CRIT "%s: called for  non-existed channel %d\n",
		       __FUNCTION__, dma_ch);
		return -EINVAL;
	}

	local_irq_save(flags);
	if (imxdma->name) {
		local_irq_restore(flags);
		return -ENODEV;
	}

	imxdma->name = name;
	imxdma->irq_handler = NULL;
	imxdma->err_handler = NULL;
	imxdma->data = NULL;
	imxdma->sg = NULL;
	local_irq_restore(flags);
	return 0;
}

/**
 * imx_dma_free - release previously acquired channel
 * @dma_ch: i.MX DMA channel number
 */
void imx_dma_free(imx_dmach_t dma_ch)
{
	unsigned long flags;
	struct imx_dma_channel *imxdma = &imx_dma_channels[dma_ch];

	if (!imxdma->name) {
		printk(KERN_CRIT
		       "%s: trying to free channel %d which is already freed\n",
		       __FUNCTION__, dma_ch);
		return;
	}

	local_irq_save(flags);
	/* Disable interrupts */
	DIMR |= (1 << dma_ch);
	CCR(dma_ch) &= ~CCR_CEN;
	imxdma->name = NULL;
	local_irq_restore(flags);
}

/**
 * imx_dma_request_by_prio - find and request some of free channels best suiting requested priority
 * @dma_ch: i.MX DMA channel number
 * @name: the driver/caller own non-%NULL identification
 * @prio: one of the hardware distinguished priority level:
 *        %DMA_PRIO_HIGH, %DMA_PRIO_MEDIUM, %DMA_PRIO_LOW
 *
 * This function tries to find free channel in the specified priority group
 * if the priority cannot be achieved it tries to look for free channel
 * in the higher and then even lower priority groups.
 *
 * Return value: If there is no free channel to allocate, -%ENODEV is returned.
 *               Zero value indicates successful channel allocation.
 */
int
imx_dma_request_by_prio(imx_dmach_t * pdma_ch, const char *name,
			imx_dma_prio prio)
{
	int i;
	int best;

	switch (prio) {
	case (DMA_PRIO_HIGH):
		best = 8;
		break;
	case (DMA_PRIO_MEDIUM):
		best = 4;
		break;
	case (DMA_PRIO_LOW):
	default:
		best = 0;
		break;
	}

	for (i = best; i < IMX_DMA_CHANNELS; i++) {
		if (!imx_dma_request(i, name)) {
			*pdma_ch = i;
			return 0;
		}
	}

	for (i = best - 1; i >= 0; i--) {
		if (!imx_dma_request(i, name)) {
			*pdma_ch = i;
			return 0;
		}
	}

	printk(KERN_ERR "%s: no free DMA channel found\n", __FUNCTION__);

	return -ENODEV;
}

static irqreturn_t dma_err_handler(int irq, void *dev_id)
{
	int i, disr = DISR;
	struct imx_dma_channel *channel;
	unsigned int err_mask = DBTOSR | DRTOSR | DSESR | DBOSR;
	int errcode;

	DISR = disr & err_mask;
	for (i = 0; i < IMX_DMA_CHANNELS; i++) {
		if(!(err_mask & (1 << i)))
			continue;
		channel = &imx_dma_channels[i];
		errcode = 0;

		if (DBTOSR & (1 << i)) {
			DBTOSR = (1 << i);
			errcode |= IMX_DMA_ERR_BURST;
		}
		if (DRTOSR & (1 << i)) {
			DRTOSR = (1 << i);
			errcode |= IMX_DMA_ERR_REQUEST;
		}
		if (DSESR & (1 << i)) {
			DSESR = (1 << i);
			errcode |= IMX_DMA_ERR_TRANSFER;
		}
		if (DBOSR & (1 << i)) {
			DBOSR = (1 << i);
			errcode |= IMX_DMA_ERR_BUFFER;
		}

		/*
		 * The cleaning of @sg field would be questionable
		 * there, because its value can help to compute
		 * remaining/transferred bytes count in the handler
		 */
		/*imx_dma_channels[i].sg = NULL;*/

		if (channel->name && channel->err_handler) {
			channel->err_handler(i, channel->data, errcode);
			continue;
		}

		imx_dma_channels[i].sg = NULL;

		printk(KERN_WARNING
		       "DMA timeout on channel %d (%s) -%s%s%s%s\n",
		       i, channel->name,
		       errcode&IMX_DMA_ERR_BURST?    " burst":"",
		       errcode&IMX_DMA_ERR_REQUEST?  " request":"",
		       errcode&IMX_DMA_ERR_TRANSFER? " transfer":"",
		       errcode&IMX_DMA_ERR_BUFFER?   " buffer":"");
	}
	return IRQ_HANDLED;
}

static irqreturn_t dma_irq_handler(int irq, void *dev_id)
{
	int i, disr = DISR;

	pr_debug("imxdma: dma_irq_handler called, disr=0x%08x\n",
		     disr);

	DISR = disr;
	for (i = 0; i < IMX_DMA_CHANNELS; i++) {
		if (disr & (1 << i)) {
			struct imx_dma_channel *channel = &imx_dma_channels[i];
			if (channel->name) {
				if (imx_dma_sg_next(i, CNTR(i))) {
					CCR(i) &= ~CCR_CEN;
					mb();
					CCR(i) |= CCR_CEN;
				} else {
					if (channel->irq_handler)
						channel->irq_handler(i,
							channel->data);
				}
			} else {
				/*
				 * IRQ for an unregistered DMA channel:
				 * let's clear the interrupts and disable it.
				 */
				printk(KERN_WARNING
				       "spurious IRQ for DMA channel %d\n", i);
			}
		}
	}
	return IRQ_HANDLED;
}

static int __init imx_dma_init(void)
{
	int ret;
	int i;

	/* reset DMA module */
	DCR = DCR_DRST;

	ret = request_irq(DMA_INT, dma_irq_handler, 0, "DMA", NULL);
	if (ret) {
		printk(KERN_CRIT "Wow!  Can't register IRQ for DMA\n");
		return ret;
	}

	ret = request_irq(DMA_ERR, dma_err_handler, 0, "DMA", NULL);
	if (ret) {
		printk(KERN_CRIT "Wow!  Can't register ERRIRQ for DMA\n");
		free_irq(DMA_INT, NULL);
	}

	/* enable DMA module */
	DCR = DCR_DEN;

	/* clear all interrupts */
	DISR = (1 << IMX_DMA_CHANNELS) - 1;

	/* enable interrupts */
	DIMR = (1 << IMX_DMA_CHANNELS) - 1;

	for (i = 0; i < IMX_DMA_CHANNELS; i++) {
		imx_dma_channels[i].sg = NULL;
		imx_dma_channels[i].dma_num = i;
	}

	return ret;
}

arch_initcall(imx_dma_init);

EXPORT_SYMBOL(imx_dma_setup_single);
EXPORT_SYMBOL(imx_dma_setup_sg);
EXPORT_SYMBOL(imx_dma_setup_handlers);
EXPORT_SYMBOL(imx_dma_enable);
EXPORT_SYMBOL(imx_dma_disable);
EXPORT_SYMBOL(imx_dma_request);
EXPORT_SYMBOL(imx_dma_free);
EXPORT_SYMBOL(imx_dma_request_by_prio);
EXPORT_SYMBOL(imx_dma_channels);