Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1066 insertions, 0 deletions

diff --git a/drivers/dma/dma-axi-dmac.c b/drivers/dma/dma-axi-dmac.c
new file mode 100644
index 000000000..f30dabc99
--- /dev/null
+++ b/drivers/dma/dma-axi-dmac.c
@@ -0,0 +1,1066 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Driver for the Analog Devices AXI-DMAC core
+ *
+ * Copyright 2013-2019 Analog Devices Inc.
+ *  Author: Lars-Peter Clausen <lars@metafoo.de>
+ */
+
+#include <linux/bitfield.h>
+#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/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+#include <linux/fpga/adi-axi-common.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_INTERFACE_DESC	0x10
+#define   AXI_DMAC_DMA_SRC_TYPE_MSK	GENMASK(13, 12)
+#define   AXI_DMAC_DMA_SRC_TYPE_GET(x)	FIELD_GET(AXI_DMAC_DMA_SRC_TYPE_MSK, x)
+#define   AXI_DMAC_DMA_SRC_WIDTH_MSK	GENMASK(11, 8)
+#define   AXI_DMAC_DMA_SRC_WIDTH_GET(x)	FIELD_GET(AXI_DMAC_DMA_SRC_WIDTH_MSK, x)
+#define   AXI_DMAC_DMA_DST_TYPE_MSK	GENMASK(5, 4)
+#define   AXI_DMAC_DMA_DST_TYPE_GET(x)	FIELD_GET(AXI_DMAC_DMA_DST_TYPE_MSK, x)
+#define   AXI_DMAC_DMA_DST_WIDTH_MSK	GENMASK(3, 0)
+#define   AXI_DMAC_DMA_DST_WIDTH_GET(x)	FIELD_GET(AXI_DMAC_DMA_DST_WIDTH_MSK, x)
+#define AXI_DMAC_REG_COHERENCY_DESC	0x14
+#define   AXI_DMAC_DST_COHERENT_MSK	BIT(0)
+#define   AXI_DMAC_DST_COHERENT_GET(x)	FIELD_GET(AXI_DMAC_DST_COHERENT_MSK, x)
+
+#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_REG_PARTIAL_XFER_LEN	0x44c
+#define AXI_DMAC_REG_PARTIAL_XFER_ID	0x450
+
+#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)
+#define AXI_DMAC_FLAG_LAST		BIT(1)
+#define AXI_DMAC_FLAG_PARTIAL_REPORT	BIT(2)
+
+#define AXI_DMAC_FLAG_PARTIAL_XFER_DONE BIT(31)
+
+/* The maximum ID allocated by the hardware is 31 */
+#define AXI_DMAC_SG_UNUSED 32U
+
+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;
+	unsigned int partial_len;
+	bool schedule_when_free;
+};
+
+struct axi_dmac_desc {
+	struct virt_dma_desc vdesc;
+	bool cyclic;
+	bool have_partial_xfer;
+
+	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 address_align_mask;
+	unsigned int length_align_mask;
+
+	bool hw_partial_xfer;
+	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;
+};
+
+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)
+		return false;
+	if ((len & chan->length_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->address_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];
+
+	/* Already queued in cyclic mode. Wait for it to finish */
+	if (sg->id != AXI_DMAC_SG_UNUSED) {
+		sg->schedule_when_free = true;
+		return;
+	}
+
+	desc->num_submitted++;
+	if (desc->num_submitted == desc->num_sgs ||
+	    desc->have_partial_xfer) {
+		if (desc->cyclic)
+			desc->num_submitted = 0; /* Start again */
+		else
+			chan->next_desc = NULL;
+		flags |= AXI_DMAC_FLAG_LAST;
+	} 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 and only a single segment, enable hw cyclic mode to avoid
+	 * unnecessary interrupts.
+	 */
+	if (chan->hw_cyclic && desc->cyclic && !desc->vdesc.tx.callback &&
+		desc->num_sgs == 1)
+		flags |= AXI_DMAC_FLAG_CYCLIC;
+
+	if (chan->hw_partial_xfer)
+		flags |= AXI_DMAC_FLAG_PARTIAL_REPORT;
+
+	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 inline unsigned int axi_dmac_total_sg_bytes(struct axi_dmac_chan *chan,
+	struct axi_dmac_sg *sg)
+{
+	if (chan->hw_2d)
+		return sg->x_len * sg->y_len;
+	else
+		return sg->x_len;
+}
+
+static void axi_dmac_dequeue_partial_xfers(struct axi_dmac_chan *chan)
+{
+	struct axi_dmac *dmac = chan_to_axi_dmac(chan);
+	struct axi_dmac_desc *desc;
+	struct axi_dmac_sg *sg;
+	u32 xfer_done, len, id, i;
+	bool found_sg;
+
+	do {
+		len = axi_dmac_read(dmac, AXI_DMAC_REG_PARTIAL_XFER_LEN);
+		id  = axi_dmac_read(dmac, AXI_DMAC_REG_PARTIAL_XFER_ID);
+
+		found_sg = false;
+		list_for_each_entry(desc, &chan->active_descs, vdesc.node) {
+			for (i = 0; i < desc->num_sgs; i++) {
+				sg = &desc->sg[i];
+				if (sg->id == AXI_DMAC_SG_UNUSED)
+					continue;
+				if (sg->id == id) {
+					desc->have_partial_xfer = true;
+					sg->partial_len = len;
+					found_sg = true;
+					break;
+				}
+			}
+			if (found_sg)
+				break;
+		}
+
+		if (found_sg) {
+			dev_dbg(dmac->dma_dev.dev,
+				"Found partial segment id=%u, len=%u\n",
+				id, len);
+		} else {
+			dev_warn(dmac->dma_dev.dev,
+				 "Not found partial segment id=%u, len=%u\n",
+				 id, len);
+		}
+
+		/* Check if we have any more partial transfers */
+		xfer_done = axi_dmac_read(dmac, AXI_DMAC_REG_TRANSFER_DONE);
+		xfer_done = !(xfer_done & AXI_DMAC_FLAG_PARTIAL_XFER_DONE);
+
+	} while (!xfer_done);
+}
+
+static void axi_dmac_compute_residue(struct axi_dmac_chan *chan,
+	struct axi_dmac_desc *active)
+{
+	struct dmaengine_result *rslt = &active->vdesc.tx_result;
+	unsigned int start = active->num_completed - 1;
+	struct axi_dmac_sg *sg;
+	unsigned int i, total;
+
+	rslt->result = DMA_TRANS_NOERROR;
+	rslt->residue = 0;
+
+	/*
+	 * We get here if the last completed segment is partial, which
+	 * means we can compute the residue from that segment onwards
+	 */
+	for (i = start; i < active->num_sgs; i++) {
+		sg = &active->sg[i];
+		total = axi_dmac_total_sg_bytes(chan, sg);
+		rslt->residue += (total - sg->partial_len);
+	}
+}
+
+static bool axi_dmac_transfer_done(struct axi_dmac_chan *chan,
+	unsigned int completed_transfers)
+{
+	struct axi_dmac_desc *active;
+	struct axi_dmac_sg *sg;
+	bool start_next = false;
+
+	active = axi_dmac_active_desc(chan);
+	if (!active)
+		return false;
+
+	if (chan->hw_partial_xfer &&
+	    (completed_transfers & AXI_DMAC_FLAG_PARTIAL_XFER_DONE))
+		axi_dmac_dequeue_partial_xfers(chan);
+
+	do {
+		sg = &active->sg[active->num_completed];
+		if (sg->id == AXI_DMAC_SG_UNUSED) /* Not yet submitted */
+			break;
+		if (!(BIT(sg->id) & completed_transfers))
+			break;
+		active->num_completed++;
+		sg->id = AXI_DMAC_SG_UNUSED;
+		if (sg->schedule_when_free) {
+			sg->schedule_when_free = false;
+			start_next = true;
+		}
+
+		if (sg->partial_len)
+			axi_dmac_compute_residue(chan, active);
+
+		if (active->cyclic)
+			vchan_cyclic_callback(&active->vdesc);
+
+		if (active->num_completed == active->num_sgs ||
+		    sg->partial_len) {
+			if (active->cyclic) {
+				active->num_completed = 0; /* wrap around */
+			} else {
+				list_del(&active->vdesc.node);
+				vchan_cookie_complete(&active->vdesc);
+				active = axi_dmac_active_desc(chan);
+			}
+		}
+	} while (active);
+
+	return start_next;
+}
+
+static irqreturn_t axi_dmac_interrupt_handler(int irq, void *devid)
+{
+	struct axi_dmac *dmac = devid;
+	unsigned int pending;
+	bool start_next = false;
+
+	pending = axi_dmac_read(dmac, AXI_DMAC_REG_IRQ_PENDING);
+	if (!pending)
+		return IRQ_NONE;
+
+	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);
+		start_next = axi_dmac_transfer_done(&dmac->chan, completed);
+	}
+	/* Space has become available in the descriptor queue */
+	if ((pending & AXI_DMAC_IRQ_SOT) || start_next)
+		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_synchronize(struct dma_chan *c)
+{
+	struct axi_dmac_chan *chan = to_axi_dmac_chan(c);
+
+	vchan_synchronize(&chan->vchan);
+}
+
+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;
+	unsigned int i;
+
+	desc = kzalloc(struct_size(desc, sg, num_sgs), GFP_NOWAIT);
+	if (!desc)
+		return NULL;
+
+	for (i = 0; i < num_sgs; i++)
+		desc->sg[i].id = AXI_DMAC_SG_UNUSED;
+
+	desc->num_sgs = num_sgs;
+
+	return desc;
+}
+
+static struct axi_dmac_sg *axi_dmac_fill_linear_sg(struct axi_dmac_chan *chan,
+	enum dma_transfer_direction direction, dma_addr_t addr,
+	unsigned int num_periods, unsigned int period_len,
+	struct axi_dmac_sg *sg)
+{
+	unsigned int num_segments, i;
+	unsigned int segment_size;
+	unsigned int len;
+
+	/* Split into multiple equally sized segments if necessary */
+	num_segments = DIV_ROUND_UP(period_len, chan->max_length);
+	segment_size = DIV_ROUND_UP(period_len, num_segments);
+	/* Take care of alignment */
+	segment_size = ((segment_size - 1) | chan->length_align_mask) + 1;
+
+	for (i = 0; i < num_periods; i++) {
+		len = period_len;
+
+		while (len > segment_size) {
+			if (direction == DMA_DEV_TO_MEM)
+				sg->dest_addr = addr;
+			else
+				sg->src_addr = addr;
+			sg->x_len = segment_size;
+			sg->y_len = 1;
+			sg++;
+			addr += segment_size;
+			len -= segment_size;
+		}
+
+		if (direction == DMA_DEV_TO_MEM)
+			sg->dest_addr = addr;
+		else
+			sg->src_addr = addr;
+		sg->x_len = len;
+		sg->y_len = 1;
+		sg++;
+		addr += len;
+	}
+
+	return sg;
+}
+
+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 axi_dmac_sg *dsg;
+	struct scatterlist *sg;
+	unsigned int num_sgs;
+	unsigned int i;
+
+	if (direction != chan->direction)
+		return NULL;
+
+	num_sgs = 0;
+	for_each_sg(sgl, sg, sg_len, i)
+		num_sgs += DIV_ROUND_UP(sg_dma_len(sg), chan->max_length);
+
+	desc = axi_dmac_alloc_desc(num_sgs);
+	if (!desc)
+		return NULL;
+
+	dsg = desc->sg;
+
+	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;
+		}
+
+		dsg = axi_dmac_fill_linear_sg(chan, direction, sg_dma_address(sg), 1,
+			sg_dma_len(sg), dsg);
+	}
+
+	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, num_segments;
+
+	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;
+	num_segments = DIV_ROUND_UP(period_len, chan->max_length);
+
+	desc = axi_dmac_alloc_desc(num_periods * num_segments);
+	if (!desc)
+		return NULL;
+
+	axi_dmac_fill_linear_sg(chan, direction, buf_addr, num_periods,
+		period_len, desc->sg);
+
+	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) ||
+		    xt->numf == 0)
+			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;
+	}
+
+	if (flags & DMA_CYCLIC)
+		desc->cyclic = true;
+
+	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));
+}
+
+static bool axi_dmac_regmap_rdwr(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case AXI_DMAC_REG_IRQ_MASK:
+	case AXI_DMAC_REG_IRQ_SOURCE:
+	case AXI_DMAC_REG_IRQ_PENDING:
+	case AXI_DMAC_REG_CTRL:
+	case AXI_DMAC_REG_TRANSFER_ID:
+	case AXI_DMAC_REG_START_TRANSFER:
+	case AXI_DMAC_REG_FLAGS:
+	case AXI_DMAC_REG_DEST_ADDRESS:
+	case AXI_DMAC_REG_SRC_ADDRESS:
+	case AXI_DMAC_REG_X_LENGTH:
+	case AXI_DMAC_REG_Y_LENGTH:
+	case AXI_DMAC_REG_DEST_STRIDE:
+	case AXI_DMAC_REG_SRC_STRIDE:
+	case AXI_DMAC_REG_TRANSFER_DONE:
+	case AXI_DMAC_REG_ACTIVE_TRANSFER_ID:
+	case AXI_DMAC_REG_STATUS:
+	case AXI_DMAC_REG_CURRENT_SRC_ADDR:
+	case AXI_DMAC_REG_CURRENT_DEST_ADDR:
+	case AXI_DMAC_REG_PARTIAL_XFER_LEN:
+	case AXI_DMAC_REG_PARTIAL_XFER_ID:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static const struct regmap_config axi_dmac_regmap_config = {
+	.reg_bits = 32,
+	.val_bits = 32,
+	.reg_stride = 4,
+	.max_register = AXI_DMAC_REG_PARTIAL_XFER_ID,
+	.readable_reg = axi_dmac_regmap_rdwr,
+	.writeable_reg = axi_dmac_regmap_rdwr,
+};
+
+static void axi_dmac_adjust_chan_params(struct axi_dmac_chan *chan)
+{
+	chan->address_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;
+}
+
+/*
+ * 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;
+
+	axi_dmac_adjust_chan_params(chan);
+
+	return 0;
+}
+
+static int axi_dmac_parse_dt(struct device *dev, struct axi_dmac *dmac)
+{
+	struct device_node *of_channels, *of_chan;
+	int ret;
+
+	of_channels = of_get_child_by_name(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);
+
+	return 0;
+}
+
+static int axi_dmac_read_chan_config(struct device *dev, struct axi_dmac *dmac)
+{
+	struct axi_dmac_chan *chan = &dmac->chan;
+	unsigned int val, desc;
+
+	desc = axi_dmac_read(dmac, AXI_DMAC_REG_INTERFACE_DESC);
+	if (desc == 0) {
+		dev_err(dev, "DMA interface register reads zero\n");
+		return -EFAULT;
+	}
+
+	val = AXI_DMAC_DMA_SRC_TYPE_GET(desc);
+	if (val > AXI_DMAC_BUS_TYPE_FIFO) {
+		dev_err(dev, "Invalid source bus type read: %d\n", val);
+		return -EINVAL;
+	}
+	chan->src_type = val;
+
+	val = AXI_DMAC_DMA_DST_TYPE_GET(desc);
+	if (val > AXI_DMAC_BUS_TYPE_FIFO) {
+		dev_err(dev, "Invalid destination bus type read: %d\n", val);
+		return -EINVAL;
+	}
+	chan->dest_type = val;
+
+	val = AXI_DMAC_DMA_SRC_WIDTH_GET(desc);
+	if (val == 0) {
+		dev_err(dev, "Source bus width is zero\n");
+		return -EINVAL;
+	}
+	/* widths are stored in log2 */
+	chan->src_width = 1 << val;
+
+	val = AXI_DMAC_DMA_DST_WIDTH_GET(desc);
+	if (val == 0) {
+		dev_err(dev, "Destination bus width is zero\n");
+		return -EINVAL;
+	}
+	chan->dest_width = 1 << val;
+
+	axi_dmac_adjust_chan_params(chan);
+
+	return 0;
+}
+
+static int axi_dmac_detect_caps(struct axi_dmac *dmac, unsigned int version)
+{
+	struct axi_dmac_chan *chan = &dmac->chan;
+
+	axi_dmac_write(dmac, AXI_DMAC_REG_FLAGS, AXI_DMAC_FLAG_CYCLIC);
+	if (axi_dmac_read(dmac, AXI_DMAC_REG_FLAGS) == AXI_DMAC_FLAG_CYCLIC)
+		chan->hw_cyclic = true;
+
+	axi_dmac_write(dmac, AXI_DMAC_REG_Y_LENGTH, 1);
+	if (axi_dmac_read(dmac, AXI_DMAC_REG_Y_LENGTH) == 1)
+		chan->hw_2d = true;
+
+	axi_dmac_write(dmac, AXI_DMAC_REG_X_LENGTH, 0xffffffff);
+	chan->max_length = axi_dmac_read(dmac, AXI_DMAC_REG_X_LENGTH);
+	if (chan->max_length != UINT_MAX)
+		chan->max_length++;
+
+	axi_dmac_write(dmac, AXI_DMAC_REG_DEST_ADDRESS, 0xffffffff);
+	if (axi_dmac_read(dmac, AXI_DMAC_REG_DEST_ADDRESS) == 0 &&
+	    chan->dest_type == AXI_DMAC_BUS_TYPE_AXI_MM) {
+		dev_err(dmac->dma_dev.dev,
+			"Destination memory-mapped interface not supported.");
+		return -ENODEV;
+	}
+
+	axi_dmac_write(dmac, AXI_DMAC_REG_SRC_ADDRESS, 0xffffffff);
+	if (axi_dmac_read(dmac, AXI_DMAC_REG_SRC_ADDRESS) == 0 &&
+	    chan->src_type == AXI_DMAC_BUS_TYPE_AXI_MM) {
+		dev_err(dmac->dma_dev.dev,
+			"Source memory-mapped interface not supported.");
+		return -ENODEV;
+	}
+
+	if (version >= ADI_AXI_PCORE_VER(4, 2, 'a'))
+		chan->hw_partial_xfer = true;
+
+	if (version >= ADI_AXI_PCORE_VER(4, 1, 'a')) {
+		axi_dmac_write(dmac, AXI_DMAC_REG_X_LENGTH, 0x00);
+		chan->length_align_mask =
+			axi_dmac_read(dmac, AXI_DMAC_REG_X_LENGTH);
+	} else {
+		chan->length_align_mask = chan->address_align_mask;
+	}
+
+	return 0;
+}
+
+static int axi_dmac_probe(struct platform_device *pdev)
+{
+	struct dma_device *dma_dev;
+	struct axi_dmac *dmac;
+	struct resource *res;
+	struct regmap *regmap;
+	unsigned int version;
+	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 dmac->irq;
+	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);
+
+	ret = clk_prepare_enable(dmac->clk);
+	if (ret < 0)
+		return ret;
+
+	version = axi_dmac_read(dmac, ADI_AXI_REG_VERSION);
+
+	if (version >= ADI_AXI_PCORE_VER(4, 3, 'a'))
+		ret = axi_dmac_read_chan_config(&pdev->dev, dmac);
+	else
+		ret = axi_dmac_parse_dt(&pdev->dev, dmac);
+
+	if (ret < 0)
+		goto err_clk_disable;
+
+	INIT_LIST_HEAD(&dmac->chan.active_descs);
+
+	dma_set_max_seg_size(&pdev->dev, UINT_MAX);
+
+	dma_dev = &dmac->dma_dev;
+	dma_cap_set(DMA_SLAVE, dma_dev->cap_mask);
+	dma_cap_set(DMA_CYCLIC, dma_dev->cap_mask);
+	dma_cap_set(DMA_INTERLEAVE, 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->device_synchronize = axi_dmac_synchronize;
+	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 = axi_dmac_detect_caps(dmac, version);
+	if (ret)
+		goto err_clk_disable;
+
+	dma_dev->copy_align = (dmac->chan.address_align_mask + 1);
+
+	axi_dmac_write(dmac, AXI_DMAC_REG_IRQ_MASK, 0x00);
+
+	if (of_dma_is_coherent(pdev->dev.of_node)) {
+		ret = axi_dmac_read(dmac, AXI_DMAC_REG_COHERENCY_DESC);
+
+		if (version < ADI_AXI_PCORE_VER(4, 4, 'a') ||
+		    !AXI_DMAC_DST_COHERENT_GET(ret)) {
+			dev_err(dmac->dma_dev.dev,
+				"Coherent DMA not supported in hardware");
+			ret = -EINVAL;
+			goto err_clk_disable;
+		}
+	}
+
+	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, IRQF_SHARED,
+		dev_name(&pdev->dev), dmac);
+	if (ret)
+		goto err_unregister_of;
+
+	platform_set_drvdata(pdev, dmac);
+
+	regmap = devm_regmap_init_mmio(&pdev->dev, dmac->base,
+		 &axi_dmac_regmap_config);
+	if (IS_ERR(regmap)) {
+		ret = PTR_ERR(regmap);
+		goto err_free_irq;
+	}
+
+	return 0;
+
+err_free_irq:
+	free_irq(dmac->irq, dmac);
+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" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, axi_dmac_of_match_table);
+
+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");