dmaengine: Add support for the Analog Devices AXI-DMAC DMA controller

Add support for the Analog Devices AXI-DMAC DMA controller. This controller
is a soft peripheral that can be instantiated in a FPGA and is often used
in Analog Devices' reference designs for FPGA platforms.

The peripheral has various configuration options that can be selected at
synthesis time and influence the supported features of the instantiated
peripheral, those options are represented as device-tree properties to
allow the driver to behave accordingly.

The peripheral has a zero latency architecture, which means it is possible
to switch from one to the next descriptor without any delay. This is
archived by having a internal queue which can hold multiple descriptors.
The driver supports this, which means it will submit new descriptors
directly to the hardware until the queue is full and not wait for a
descriptor to complete before the next one is submitted. Interrupts are
used for the descriptor queue flow control.

Currently the driver supports SG, cyclic and interleaved slave DMA.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

3 files changed, 702 insertions, 0 deletions

diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
index 84682538610e..81e1937fcd6d 100644
--- a/drivers/dma/Kconfig
+++ b/drivers/dma/Kconfig
@@ -534,4 +534,14 @@ config QCOM_BAM_DMA
 	  Enable support for the QCOM BAM DMA controller.  This controller
 	  provides DMA capabilities for a variety of on-chip devices.
 
+config AXI_DMAC
+	tristate "Analog Devices AXI-DMAC DMA support"
+	depends on MICROBLAZE || NIOS2 || ARCH_ZYNQ || ARCH_SOCFPGA || COMPILE_TEST
+	select DMA_ENGINE
+	select DMA_VIRTUAL_CHANNELS
+	help
+	  Enable support for the Analog Devices AXI-DMAC peripheral. This DMA
+	  controller is often used in Analog Device's reference designs for FPGA
+	  platforms.
+
 endif
diff --git a/drivers/dma/Makefile b/drivers/dma/Makefile
index d056a8ad6ab1..a4809849b6c5 100644
--- a/drivers/dma/Makefile
+++ b/drivers/dma/Makefile
@@ -59,3 +59,4 @@ obj-$(CONFIG_DMA_SUN4I) += sun4i-dma.o
 obj-$(CONFIG_IMG_MDC_DMA) += img-mdc-dma.o
 obj-$(CONFIG_XGENE_DMA) += xgene-dma.o
 obj-$(CONFIG_ZX_DMA) += zx296702_dma.o
+obj-$(CONFIG_AXI_DMAC) += dma-axi-dmac.o
diff --git a/drivers/dma/dma-axi-dmac.c b/drivers/dma/dma-axi-dmac.c
new file mode 100644
index 000000000000..5b2395e7e04d
--- /dev/null
+++ b/drivers/dma/dma-axi-dmac.c
@@ -0,0 +1,691 @@
+/*
+ * Driver for the Analog Devices AXI-DMAC core
+ *
+ * Copyright 2013-2015 Analog Devices Inc.
+ *  Author: Lars-Peter Clausen <lars@metafoo.de>
+ *
+ * Licensed under the GPL-2.
+ */
+
+#include <linux/clk.h>
+#include <linux/device.h>
+#include <linux/dma-mapping.h>
+#include <linux/dmaengine.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_dma.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+#include <dt-bindings/dma/axi-dmac.h>
+
+#include "dmaengine.h"
+#include "virt-dma.h"
+
+/*
+ * The AXI-DMAC is a soft IP core that is used in FPGA designs. The core has
+ * various instantiation parameters which decided the exact feature set support
+ * by the core.
+ *
+ * Each channel of the core has a source interface and a destination interface.
+ * The number of channels and the type of the channel interfaces is selected at
+ * configuration time. A interface can either be a connected to a central memory
+ * interconnect, which allows access to system memory, or it can be connected to
+ * a dedicated bus which is directly connected to a data port on a peripheral.
+ * Given that those are configuration options of the core that are selected when
+ * it is instantiated this means that they can not be changed by software at
+ * runtime. By extension this means that each channel is uni-directional. It can
+ * either be device to memory or memory to device, but not both. Also since the
+ * device side is a dedicated data bus only connected to a single peripheral
+ * there is no address than can or needs to be configured for the device side.
+ */
+
+#define AXI_DMAC_REG_IRQ_MASK		0x80
+#define AXI_DMAC_REG_IRQ_PENDING	0x84
+#define AXI_DMAC_REG_IRQ_SOURCE		0x88
+
+#define AXI_DMAC_REG_CTRL		0x400
+#define AXI_DMAC_REG_TRANSFER_ID	0x404
+#define AXI_DMAC_REG_START_TRANSFER	0x408
+#define AXI_DMAC_REG_FLAGS		0x40c
+#define AXI_DMAC_REG_DEST_ADDRESS	0x410
+#define AXI_DMAC_REG_SRC_ADDRESS	0x414
+#define AXI_DMAC_REG_X_LENGTH		0x418
+#define AXI_DMAC_REG_Y_LENGTH		0x41c
+#define AXI_DMAC_REG_DEST_STRIDE	0x420
+#define AXI_DMAC_REG_SRC_STRIDE		0x424
+#define AXI_DMAC_REG_TRANSFER_DONE	0x428
+#define AXI_DMAC_REG_ACTIVE_TRANSFER_ID 0x42c
+#define AXI_DMAC_REG_STATUS		0x430
+#define AXI_DMAC_REG_CURRENT_SRC_ADDR	0x434
+#define AXI_DMAC_REG_CURRENT_DEST_ADDR	0x438
+
+#define AXI_DMAC_CTRL_ENABLE		BIT(0)
+#define AXI_DMAC_CTRL_PAUSE		BIT(1)
+
+#define AXI_DMAC_IRQ_SOT		BIT(0)
+#define AXI_DMAC_IRQ_EOT		BIT(1)
+
+#define AXI_DMAC_FLAG_CYCLIC		BIT(0)
+
+struct axi_dmac_sg {
+	dma_addr_t src_addr;
+	dma_addr_t dest_addr;
+	unsigned int x_len;
+	unsigned int y_len;
+	unsigned int dest_stride;
+	unsigned int src_stride;
+	unsigned int id;
+};
+
+struct axi_dmac_desc {
+	struct virt_dma_desc vdesc;
+	bool cyclic;
+
+	unsigned int num_submitted;
+	unsigned int num_completed;
+	unsigned int num_sgs;
+	struct axi_dmac_sg sg[];
+};
+
+struct axi_dmac_chan {
+	struct virt_dma_chan vchan;
+
+	struct axi_dmac_desc *next_desc;
+	struct list_head active_descs;
+	enum dma_transfer_direction direction;
+
+	unsigned int src_width;
+	unsigned int dest_width;
+	unsigned int src_type;
+	unsigned int dest_type;
+
+	unsigned int max_length;
+	unsigned int align_mask;
+
+	bool hw_cyclic;
+	bool hw_2d;
+};
+
+struct axi_dmac {
+	void __iomem *base;
+	int irq;
+
+	struct clk *clk;
+
+	struct dma_device dma_dev;
+	struct axi_dmac_chan chan;
+
+	struct device_dma_parameters dma_parms;
+};
+
+static struct axi_dmac *chan_to_axi_dmac(struct axi_dmac_chan *chan)
+{
+	return container_of(chan->vchan.chan.device, struct axi_dmac,
+		dma_dev);
+}
+
+static struct axi_dmac_chan *to_axi_dmac_chan(struct dma_chan *c)
+{
+	return container_of(c, struct axi_dmac_chan, vchan.chan);
+}
+
+static struct axi_dmac_desc *to_axi_dmac_desc(struct virt_dma_desc *vdesc)
+{
+	return container_of(vdesc, struct axi_dmac_desc, vdesc);
+}
+
+static void axi_dmac_write(struct axi_dmac *axi_dmac, unsigned int reg,
+	unsigned int val)
+{
+	writel(val, axi_dmac->base + reg);
+}
+
+static int axi_dmac_read(struct axi_dmac *axi_dmac, unsigned int reg)
+{
+	return readl(axi_dmac->base + reg);
+}
+
+static int axi_dmac_src_is_mem(struct axi_dmac_chan *chan)
+{
+	return chan->src_type == AXI_DMAC_BUS_TYPE_AXI_MM;
+}
+
+static int axi_dmac_dest_is_mem(struct axi_dmac_chan *chan)
+{
+	return chan->dest_type == AXI_DMAC_BUS_TYPE_AXI_MM;
+}
+
+static bool axi_dmac_check_len(struct axi_dmac_chan *chan, unsigned int len)
+{
+	if (len == 0 || len > chan->max_length)
+		return false;
+	if ((len & chan->align_mask) != 0) /* Not aligned */
+		return false;
+	return true;
+}
+
+static bool axi_dmac_check_addr(struct axi_dmac_chan *chan, dma_addr_t addr)
+{
+	if ((addr & chan->align_mask) != 0) /* Not aligned */
+		return false;
+	return true;
+}
+
+static void axi_dmac_start_transfer(struct axi_dmac_chan *chan)
+{
+	struct axi_dmac *dmac = chan_to_axi_dmac(chan);
+	struct virt_dma_desc *vdesc;
+	struct axi_dmac_desc *desc;
+	struct axi_dmac_sg *sg;
+	unsigned int flags = 0;
+	unsigned int val;
+
+	val = axi_dmac_read(dmac, AXI_DMAC_REG_START_TRANSFER);
+	if (val) /* Queue is full, wait for the next SOT IRQ */
+		return;
+
+	desc = chan->next_desc;
+
+	if (!desc) {
+		vdesc = vchan_next_desc(&chan->vchan);
+		if (!vdesc)
+			return;
+		list_move_tail(&vdesc->node, &chan->active_descs);
+		desc = to_axi_dmac_desc(vdesc);
+	}
+	sg = &desc->sg[desc->num_submitted];
+
+	desc->num_submitted++;
+	if (desc->num_submitted == desc->num_sgs)
+		chan->next_desc = NULL;
+	else
+		chan->next_desc = desc;
+
+	sg->id = axi_dmac_read(dmac, AXI_DMAC_REG_TRANSFER_ID);
+
+	if (axi_dmac_dest_is_mem(chan)) {
+		axi_dmac_write(dmac, AXI_DMAC_REG_DEST_ADDRESS, sg->dest_addr);
+		axi_dmac_write(dmac, AXI_DMAC_REG_DEST_STRIDE, sg->dest_stride);
+	}
+
+	if (axi_dmac_src_is_mem(chan)) {
+		axi_dmac_write(dmac, AXI_DMAC_REG_SRC_ADDRESS, sg->src_addr);
+		axi_dmac_write(dmac, AXI_DMAC_REG_SRC_STRIDE, sg->src_stride);
+	}
+
+	/*
+	 * If the hardware supports cyclic transfers and there is no callback to
+	 * call, enable hw cyclic mode to avoid unnecessary interrupts.
+	 */
+	if (chan->hw_cyclic && desc->cyclic && !desc->vdesc.tx.callback)
+		flags |= AXI_DMAC_FLAG_CYCLIC;
+
+	axi_dmac_write(dmac, AXI_DMAC_REG_X_LENGTH, sg->x_len - 1);
+	axi_dmac_write(dmac, AXI_DMAC_REG_Y_LENGTH, sg->y_len - 1);
+	axi_dmac_write(dmac, AXI_DMAC_REG_FLAGS, flags);
+	axi_dmac_write(dmac, AXI_DMAC_REG_START_TRANSFER, 1);
+}
+
+static struct axi_dmac_desc *axi_dmac_active_desc(struct axi_dmac_chan *chan)
+{
+	return list_first_entry_or_null(&chan->active_descs,
+		struct axi_dmac_desc, vdesc.node);
+}
+
+static void axi_dmac_transfer_done(struct axi_dmac_chan *chan,
+	unsigned int completed_transfers)
+{
+	struct axi_dmac_desc *active;
+	struct axi_dmac_sg *sg;
+
+	active = axi_dmac_active_desc(chan);
+	if (!active)
+		return;
+
+	if (active->cyclic) {
+		vchan_cyclic_callback(&active->vdesc);
+	} else {
+		do {
+			sg = &active->sg[active->num_completed];
+			if (!(BIT(sg->id) & completed_transfers))
+				break;
+			active->num_completed++;
+			if (active->num_completed == active->num_sgs) {
+				list_del(&active->vdesc.node);
+				vchan_cookie_complete(&active->vdesc);
+				active = axi_dmac_active_desc(chan);
+			}
+		} while (active);
+	}
+}
+
+static irqreturn_t axi_dmac_interrupt_handler(int irq, void *devid)
+{
+	struct axi_dmac *dmac = devid;
+	unsigned int pending;
+
+	pending = axi_dmac_read(dmac, AXI_DMAC_REG_IRQ_PENDING);
+	axi_dmac_write(dmac, AXI_DMAC_REG_IRQ_PENDING, pending);
+
+	spin_lock(&dmac->chan.vchan.lock);
+	/* One or more transfers have finished */
+	if (pending & AXI_DMAC_IRQ_EOT) {
+		unsigned int completed;
+
+		completed = axi_dmac_read(dmac, AXI_DMAC_REG_TRANSFER_DONE);
+		axi_dmac_transfer_done(&dmac->chan, completed);
+	}
+	/* Space has become available in the descriptor queue */
+	if (pending & AXI_DMAC_IRQ_SOT)
+		axi_dmac_start_transfer(&dmac->chan);
+	spin_unlock(&dmac->chan.vchan.lock);
+
+	return IRQ_HANDLED;
+}
+
+static int axi_dmac_terminate_all(struct dma_chan *c)
+{
+	struct axi_dmac_chan *chan = to_axi_dmac_chan(c);
+	struct axi_dmac *dmac = chan_to_axi_dmac(chan);
+	unsigned long flags;
+	LIST_HEAD(head);
+
+	spin_lock_irqsave(&chan->vchan.lock, flags);
+	axi_dmac_write(dmac, AXI_DMAC_REG_CTRL, 0);
+	chan->next_desc = NULL;
+	vchan_get_all_descriptors(&chan->vchan, &head);
+	list_splice_tail_init(&chan->active_descs, &head);
+	spin_unlock_irqrestore(&chan->vchan.lock, flags);
+
+	vchan_dma_desc_free_list(&chan->vchan, &head);
+
+	return 0;
+}
+
+static void axi_dmac_issue_pending(struct dma_chan *c)
+{
+	struct axi_dmac_chan *chan = to_axi_dmac_chan(c);
+	struct axi_dmac *dmac = chan_to_axi_dmac(chan);
+	unsigned long flags;
+
+	axi_dmac_write(dmac, AXI_DMAC_REG_CTRL, AXI_DMAC_CTRL_ENABLE);
+
+	spin_lock_irqsave(&chan->vchan.lock, flags);
+	if (vchan_issue_pending(&chan->vchan))
+		axi_dmac_start_transfer(chan);
+	spin_unlock_irqrestore(&chan->vchan.lock, flags);
+}
+
+static struct axi_dmac_desc *axi_dmac_alloc_desc(unsigned int num_sgs)
+{
+	struct axi_dmac_desc *desc;
+
+	desc = kzalloc(sizeof(struct axi_dmac_desc) +
+		sizeof(struct axi_dmac_sg) * num_sgs, GFP_NOWAIT);
+	if (!desc)
+		return NULL;
+
+	desc->num_sgs = num_sgs;
+
+	return desc;
+}
+
+static struct dma_async_tx_descriptor *axi_dmac_prep_slave_sg(
+	struct dma_chan *c, struct scatterlist *sgl,
+	unsigned int sg_len, enum dma_transfer_direction direction,
+	unsigned long flags, void *context)
+{
+	struct axi_dmac_chan *chan = to_axi_dmac_chan(c);
+	struct axi_dmac_desc *desc;
+	struct scatterlist *sg;
+	unsigned int i;
+
+	if (direction != chan->direction)
+		return NULL;
+
+	desc = axi_dmac_alloc_desc(sg_len);
+	if (!desc)
+		return NULL;
+
+	for_each_sg(sgl, sg, sg_len, i) {
+		if (!axi_dmac_check_addr(chan, sg_dma_address(sg)) ||
+		    !axi_dmac_check_len(chan, sg_dma_len(sg))) {
+			kfree(desc);
+			return NULL;
+		}
+
+		if (direction == DMA_DEV_TO_MEM)
+			desc->sg[i].dest_addr = sg_dma_address(sg);
+		else
+			desc->sg[i].src_addr = sg_dma_address(sg);
+		desc->sg[i].x_len = sg_dma_len(sg);
+		desc->sg[i].y_len = 1;
+	}
+
+	desc->cyclic = false;
+
+	return vchan_tx_prep(&chan->vchan, &desc->vdesc, flags);
+}
+
+static struct dma_async_tx_descriptor *axi_dmac_prep_dma_cyclic(
+	struct dma_chan *c, dma_addr_t buf_addr, size_t buf_len,
+	size_t period_len, enum dma_transfer_direction direction,
+	unsigned long flags)
+{
+	struct axi_dmac_chan *chan = to_axi_dmac_chan(c);
+	struct axi_dmac_desc *desc;
+	unsigned int num_periods, i;
+
+	if (direction != chan->direction)
+		return NULL;
+
+	if (!axi_dmac_check_len(chan, buf_len) ||
+	    !axi_dmac_check_addr(chan, buf_addr))
+		return NULL;
+
+	if (period_len == 0 || buf_len % period_len)
+		return NULL;
+
+	num_periods = buf_len / period_len;
+
+	desc = axi_dmac_alloc_desc(num_periods);
+	if (!desc)
+		return NULL;
+
+	for (i = 0; i < num_periods; i++) {
+		if (direction == DMA_DEV_TO_MEM)
+			desc->sg[i].dest_addr = buf_addr;
+		else
+			desc->sg[i].src_addr = buf_addr;
+		desc->sg[i].x_len = period_len;
+		desc->sg[i].y_len = 1;
+		buf_addr += period_len;
+	}
+
+	desc->cyclic = true;
+
+	return vchan_tx_prep(&chan->vchan, &desc->vdesc, flags);
+}
+
+static struct dma_async_tx_descriptor *axi_dmac_prep_interleaved(
+	struct dma_chan *c, struct dma_interleaved_template *xt,
+	unsigned long flags)
+{
+	struct axi_dmac_chan *chan = to_axi_dmac_chan(c);
+	struct axi_dmac_desc *desc;
+	size_t dst_icg, src_icg;
+
+	if (xt->frame_size != 1)
+		return NULL;
+
+	if (xt->dir != chan->direction)
+		return NULL;
+
+	if (axi_dmac_src_is_mem(chan)) {
+		if (!xt->src_inc || !axi_dmac_check_addr(chan, xt->src_start))
+			return NULL;
+	}
+
+	if (axi_dmac_dest_is_mem(chan)) {
+		if (!xt->dst_inc || !axi_dmac_check_addr(chan, xt->dst_start))
+			return NULL;
+	}
+
+	dst_icg = dmaengine_get_dst_icg(xt, &xt->sgl[0]);
+	src_icg = dmaengine_get_src_icg(xt, &xt->sgl[0]);
+
+	if (chan->hw_2d) {
+		if (!axi_dmac_check_len(chan, xt->sgl[0].size) ||
+		    !axi_dmac_check_len(chan, xt->numf))
+			return NULL;
+		if (xt->sgl[0].size + dst_icg > chan->max_length ||
+		    xt->sgl[0].size + src_icg > chan->max_length)
+			return NULL;
+	} else {
+		if (dst_icg != 0 || src_icg != 0)
+			return NULL;
+		if (chan->max_length / xt->sgl[0].size < xt->numf)
+			return NULL;
+		if (!axi_dmac_check_len(chan, xt->sgl[0].size * xt->numf))
+			return NULL;
+	}
+
+	desc = axi_dmac_alloc_desc(1);
+	if (!desc)
+		return NULL;
+
+	if (axi_dmac_src_is_mem(chan)) {
+		desc->sg[0].src_addr = xt->src_start;
+		desc->sg[0].src_stride = xt->sgl[0].size + src_icg;
+	}
+
+	if (axi_dmac_dest_is_mem(chan)) {
+		desc->sg[0].dest_addr = xt->dst_start;
+		desc->sg[0].dest_stride = xt->sgl[0].size + dst_icg;
+	}
+
+	if (chan->hw_2d) {
+		desc->sg[0].x_len = xt->sgl[0].size;
+		desc->sg[0].y_len = xt->numf;
+	} else {
+		desc->sg[0].x_len = xt->sgl[0].size * xt->numf;
+		desc->sg[0].y_len = 1;
+	}
+
+	return vchan_tx_prep(&chan->vchan, &desc->vdesc, flags);
+}
+
+static void axi_dmac_free_chan_resources(struct dma_chan *c)
+{
+	vchan_free_chan_resources(to_virt_chan(c));
+}
+
+static void axi_dmac_desc_free(struct virt_dma_desc *vdesc)
+{
+	kfree(container_of(vdesc, struct axi_dmac_desc, vdesc));
+}
+
+/*
+ * The configuration stored in the devicetree matches the configuration
+ * parameters of the peripheral instance and allows the driver to know which
+ * features are implemented and how it should behave.
+ */
+static int axi_dmac_parse_chan_dt(struct device_node *of_chan,
+	struct axi_dmac_chan *chan)
+{
+	u32 val;
+	int ret;
+
+	ret = of_property_read_u32(of_chan, "reg", &val);
+	if (ret)
+		return ret;
+
+	/* We only support 1 channel for now */
+	if (val != 0)
+		return -EINVAL;
+
+	ret = of_property_read_u32(of_chan, "adi,source-bus-type", &val);
+	if (ret)
+		return ret;
+	if (val > AXI_DMAC_BUS_TYPE_FIFO)
+		return -EINVAL;
+	chan->src_type = val;
+
+	ret = of_property_read_u32(of_chan, "adi,destination-bus-type", &val);
+	if (ret)
+		return ret;
+	if (val > AXI_DMAC_BUS_TYPE_FIFO)
+		return -EINVAL;
+	chan->dest_type = val;
+
+	ret = of_property_read_u32(of_chan, "adi,source-bus-width", &val);
+	if (ret)
+		return ret;
+	chan->src_width = val / 8;
+
+	ret = of_property_read_u32(of_chan, "adi,destination-bus-width", &val);
+	if (ret)
+		return ret;
+	chan->dest_width = val / 8;
+
+	ret = of_property_read_u32(of_chan, "adi,length-width", &val);
+	if (ret)
+		return ret;
+
+	if (val >= 32)
+		chan->max_length = UINT_MAX;
+	else
+		chan->max_length = (1ULL << val) - 1;
+
+	chan->align_mask = max(chan->dest_width, chan->src_width) - 1;
+
+	if (axi_dmac_dest_is_mem(chan) && axi_dmac_src_is_mem(chan))
+		chan->direction = DMA_MEM_TO_MEM;
+	else if (!axi_dmac_dest_is_mem(chan) && axi_dmac_src_is_mem(chan))
+		chan->direction = DMA_MEM_TO_DEV;
+	else if (axi_dmac_dest_is_mem(chan) && !axi_dmac_src_is_mem(chan))
+		chan->direction = DMA_DEV_TO_MEM;
+	else
+		chan->direction = DMA_DEV_TO_DEV;
+
+	chan->hw_cyclic = of_property_read_bool(of_chan, "adi,cyclic");
+	chan->hw_2d = of_property_read_bool(of_chan, "adi,2d");
+
+	return 0;
+}
+
+static int axi_dmac_probe(struct platform_device *pdev)
+{
+	struct device_node *of_channels, *of_chan;
+	struct dma_device *dma_dev;
+	struct axi_dmac *dmac;
+	struct resource *res;
+	int ret;
+
+	dmac = devm_kzalloc(&pdev->dev, sizeof(*dmac), GFP_KERNEL);
+	if (!dmac)
+		return -ENOMEM;
+
+	dmac->irq = platform_get_irq(pdev, 0);
+	if (dmac->irq <= 0)
+		return -EINVAL;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	dmac->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(dmac->base))
+		return PTR_ERR(dmac->base);
+
+	dmac->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(dmac->clk))
+		return PTR_ERR(dmac->clk);
+
+	INIT_LIST_HEAD(&dmac->chan.active_descs);
+
+	of_channels = of_get_child_by_name(pdev->dev.of_node, "adi,channels");
+	if (of_channels == NULL)
+		return -ENODEV;
+
+	for_each_child_of_node(of_channels, of_chan) {
+		ret = axi_dmac_parse_chan_dt(of_chan, &dmac->chan);
+		if (ret) {
+			of_node_put(of_chan);
+			of_node_put(of_channels);
+			return -EINVAL;
+		}
+	}
+	of_node_put(of_channels);
+
+	pdev->dev.dma_parms = &dmac->dma_parms;
+	dma_set_max_seg_size(&pdev->dev, dmac->chan.max_length);
+
+	dma_dev = &dmac->dma_dev;
+	dma_cap_set(DMA_SLAVE, dma_dev->cap_mask);
+	dma_cap_set(DMA_CYCLIC, dma_dev->cap_mask);
+	dma_dev->device_free_chan_resources = axi_dmac_free_chan_resources;
+	dma_dev->device_tx_status = dma_cookie_status;
+	dma_dev->device_issue_pending = axi_dmac_issue_pending;
+	dma_dev->device_prep_slave_sg = axi_dmac_prep_slave_sg;
+	dma_dev->device_prep_dma_cyclic = axi_dmac_prep_dma_cyclic;
+	dma_dev->device_prep_interleaved_dma = axi_dmac_prep_interleaved;
+	dma_dev->device_terminate_all = axi_dmac_terminate_all;
+	dma_dev->dev = &pdev->dev;
+	dma_dev->chancnt = 1;
+	dma_dev->src_addr_widths = BIT(dmac->chan.src_width);
+	dma_dev->dst_addr_widths = BIT(dmac->chan.dest_width);
+	dma_dev->directions = BIT(dmac->chan.direction);
+	dma_dev->residue_granularity = DMA_RESIDUE_GRANULARITY_DESCRIPTOR;
+	INIT_LIST_HEAD(&dma_dev->channels);
+
+	dmac->chan.vchan.desc_free = axi_dmac_desc_free;
+	vchan_init(&dmac->chan.vchan, dma_dev);
+
+	ret = clk_prepare_enable(dmac->clk);
+	if (ret < 0)
+		return ret;
+
+	axi_dmac_write(dmac, AXI_DMAC_REG_IRQ_MASK, 0x00);
+
+	ret = dma_async_device_register(dma_dev);
+	if (ret)
+		goto err_clk_disable;
+
+	ret = of_dma_controller_register(pdev->dev.of_node,
+		of_dma_xlate_by_chan_id, dma_dev);
+	if (ret)
+		goto err_unregister_device;
+
+	ret = request_irq(dmac->irq, axi_dmac_interrupt_handler, 0,
+		dev_name(&pdev->dev), dmac);
+	if (ret)
+		goto err_unregister_of;
+
+	platform_set_drvdata(pdev, dmac);
+
+	return 0;
+
+err_unregister_of:
+	of_dma_controller_free(pdev->dev.of_node);
+err_unregister_device:
+	dma_async_device_unregister(&dmac->dma_dev);
+err_clk_disable:
+	clk_disable_unprepare(dmac->clk);
+
+	return ret;
+}
+
+static int axi_dmac_remove(struct platform_device *pdev)
+{
+	struct axi_dmac *dmac = platform_get_drvdata(pdev);
+
+	of_dma_controller_free(pdev->dev.of_node);
+	free_irq(dmac->irq, dmac);
+	tasklet_kill(&dmac->chan.vchan.task);
+	dma_async_device_unregister(&dmac->dma_dev);
+	clk_disable_unprepare(dmac->clk);
+
+	return 0;
+}
+
+static const struct of_device_id axi_dmac_of_match_table[] = {
+	{ .compatible = "adi,axi-dmac-1.00.a" },
+	{ },
+};
+
+static struct platform_driver axi_dmac_driver = {
+	.driver = {
+		.name = "dma-axi-dmac",
+		.of_match_table = axi_dmac_of_match_table,
+	},
+	.probe = axi_dmac_probe,
+	.remove = axi_dmac_remove,
+};
+module_platform_driver(axi_dmac_driver);
+
+MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
+MODULE_DESCRIPTION("DMA controller driver for the AXI-DMAC controller");
+MODULE_LICENSE("GPL v2");