Initial import

1 files changed, 877 insertions, 0 deletions

diff --git a/drivers/dma/dma-jz4780.c b/drivers/dma/dma-jz4780.c
new file mode 100644
index 000000000..26d2f0e09
--- /dev/null
+++ b/drivers/dma/dma-jz4780.c
@@ -0,0 +1,877 @@
+/*
+ * Ingenic JZ4780 DMA controller
+ *
+ * Copyright (c) 2015 Imagination Technologies
+ * Author: Alex Smith <alex@alex-smith.me.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation;  either version 2 of the  License, or (at your
+ * option) any later version.
+ */
+
+#include <linux/clk.h>
+#include <linux/dmapool.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_dma.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+#include "dmaengine.h"
+#include "virt-dma.h"
+
+#define JZ_DMA_NR_CHANNELS	32
+
+/* Global registers. */
+#define JZ_DMA_REG_DMAC		0x1000
+#define JZ_DMA_REG_DIRQP	0x1004
+#define JZ_DMA_REG_DDR		0x1008
+#define JZ_DMA_REG_DDRS		0x100c
+#define JZ_DMA_REG_DMACP	0x101c
+#define JZ_DMA_REG_DSIRQP	0x1020
+#define JZ_DMA_REG_DSIRQM	0x1024
+#define JZ_DMA_REG_DCIRQP	0x1028
+#define JZ_DMA_REG_DCIRQM	0x102c
+
+/* Per-channel registers. */
+#define JZ_DMA_REG_CHAN(n)	(n * 0x20)
+#define JZ_DMA_REG_DSA(n)	(0x00 + JZ_DMA_REG_CHAN(n))
+#define JZ_DMA_REG_DTA(n)	(0x04 + JZ_DMA_REG_CHAN(n))
+#define JZ_DMA_REG_DTC(n)	(0x08 + JZ_DMA_REG_CHAN(n))
+#define JZ_DMA_REG_DRT(n)	(0x0c + JZ_DMA_REG_CHAN(n))
+#define JZ_DMA_REG_DCS(n)	(0x10 + JZ_DMA_REG_CHAN(n))
+#define JZ_DMA_REG_DCM(n)	(0x14 + JZ_DMA_REG_CHAN(n))
+#define JZ_DMA_REG_DDA(n)	(0x18 + JZ_DMA_REG_CHAN(n))
+#define JZ_DMA_REG_DSD(n)	(0x1c + JZ_DMA_REG_CHAN(n))
+
+#define JZ_DMA_DMAC_DMAE	BIT(0)
+#define JZ_DMA_DMAC_AR		BIT(2)
+#define JZ_DMA_DMAC_HLT		BIT(3)
+#define JZ_DMA_DMAC_FMSC	BIT(31)
+
+#define JZ_DMA_DRT_AUTO		0x8
+
+#define JZ_DMA_DCS_CTE		BIT(0)
+#define JZ_DMA_DCS_HLT		BIT(2)
+#define JZ_DMA_DCS_TT		BIT(3)
+#define JZ_DMA_DCS_AR		BIT(4)
+#define JZ_DMA_DCS_DES8		BIT(30)
+
+#define JZ_DMA_DCM_LINK		BIT(0)
+#define JZ_DMA_DCM_TIE		BIT(1)
+#define JZ_DMA_DCM_STDE		BIT(2)
+#define JZ_DMA_DCM_TSZ_SHIFT	8
+#define JZ_DMA_DCM_TSZ_MASK	(0x7 << JZ_DMA_DCM_TSZ_SHIFT)
+#define JZ_DMA_DCM_DP_SHIFT	12
+#define JZ_DMA_DCM_SP_SHIFT	14
+#define JZ_DMA_DCM_DAI		BIT(22)
+#define JZ_DMA_DCM_SAI		BIT(23)
+
+#define JZ_DMA_SIZE_4_BYTE	0x0
+#define JZ_DMA_SIZE_1_BYTE	0x1
+#define JZ_DMA_SIZE_2_BYTE	0x2
+#define JZ_DMA_SIZE_16_BYTE	0x3
+#define JZ_DMA_SIZE_32_BYTE	0x4
+#define JZ_DMA_SIZE_64_BYTE	0x5
+#define JZ_DMA_SIZE_128_BYTE	0x6
+
+#define JZ_DMA_WIDTH_32_BIT	0x0
+#define JZ_DMA_WIDTH_8_BIT	0x1
+#define JZ_DMA_WIDTH_16_BIT	0x2
+
+#define JZ_DMA_BUSWIDTHS	(BIT(DMA_SLAVE_BUSWIDTH_1_BYTE)	 | \
+				 BIT(DMA_SLAVE_BUSWIDTH_2_BYTES) | \
+				 BIT(DMA_SLAVE_BUSWIDTH_4_BYTES))
+
+/**
+ * struct jz4780_dma_hwdesc - descriptor structure read by the DMA controller.
+ * @dcm: value for the DCM (channel command) register
+ * @dsa: source address
+ * @dta: target address
+ * @dtc: transfer count (number of blocks of the transfer size specified in DCM
+ * to transfer) in the low 24 bits, offset of the next descriptor from the
+ * descriptor base address in the upper 8 bits.
+ * @sd: target/source stride difference (in stride transfer mode).
+ * @drt: request type
+ */
+struct jz4780_dma_hwdesc {
+	uint32_t dcm;
+	uint32_t dsa;
+	uint32_t dta;
+	uint32_t dtc;
+	uint32_t sd;
+	uint32_t drt;
+	uint32_t reserved[2];
+};
+
+/* Size of allocations for hardware descriptor blocks. */
+#define JZ_DMA_DESC_BLOCK_SIZE	PAGE_SIZE
+#define JZ_DMA_MAX_DESC		\
+	(JZ_DMA_DESC_BLOCK_SIZE / sizeof(struct jz4780_dma_hwdesc))
+
+struct jz4780_dma_desc {
+	struct virt_dma_desc vdesc;
+
+	struct jz4780_dma_hwdesc *desc;
+	dma_addr_t desc_phys;
+	unsigned int count;
+	enum dma_transaction_type type;
+	uint32_t status;
+};
+
+struct jz4780_dma_chan {
+	struct virt_dma_chan vchan;
+	unsigned int id;
+	struct dma_pool *desc_pool;
+
+	uint32_t transfer_type;
+	uint32_t transfer_shift;
+	struct dma_slave_config	config;
+
+	struct jz4780_dma_desc *desc;
+	unsigned int curr_hwdesc;
+};
+
+struct jz4780_dma_dev {
+	struct dma_device dma_device;
+	void __iomem *base;
+	struct clk *clk;
+	unsigned int irq;
+
+	uint32_t chan_reserved;
+	struct jz4780_dma_chan chan[JZ_DMA_NR_CHANNELS];
+};
+
+struct jz4780_dma_data {
+	uint32_t transfer_type;
+	int channel;
+};
+
+static inline struct jz4780_dma_chan *to_jz4780_dma_chan(struct dma_chan *chan)
+{
+	return container_of(chan, struct jz4780_dma_chan, vchan.chan);
+}
+
+static inline struct jz4780_dma_desc *to_jz4780_dma_desc(
+	struct virt_dma_desc *vdesc)
+{
+	return container_of(vdesc, struct jz4780_dma_desc, vdesc);
+}
+
+static inline struct jz4780_dma_dev *jz4780_dma_chan_parent(
+	struct jz4780_dma_chan *jzchan)
+{
+	return container_of(jzchan->vchan.chan.device, struct jz4780_dma_dev,
+			    dma_device);
+}
+
+static inline uint32_t jz4780_dma_readl(struct jz4780_dma_dev *jzdma,
+	unsigned int reg)
+{
+	return readl(jzdma->base + reg);
+}
+
+static inline void jz4780_dma_writel(struct jz4780_dma_dev *jzdma,
+	unsigned int reg, uint32_t val)
+{
+	writel(val, jzdma->base + reg);
+}
+
+static struct jz4780_dma_desc *jz4780_dma_desc_alloc(
+	struct jz4780_dma_chan *jzchan, unsigned int count,
+	enum dma_transaction_type type)
+{
+	struct jz4780_dma_desc *desc;
+
+	if (count > JZ_DMA_MAX_DESC)
+		return NULL;
+
+	desc = kzalloc(sizeof(*desc), GFP_NOWAIT);
+	if (!desc)
+		return NULL;
+
+	desc->desc = dma_pool_alloc(jzchan->desc_pool, GFP_NOWAIT,
+				    &desc->desc_phys);
+	if (!desc->desc) {
+		kfree(desc);
+		return NULL;
+	}
+
+	desc->count = count;
+	desc->type = type;
+	return desc;
+}
+
+static void jz4780_dma_desc_free(struct virt_dma_desc *vdesc)
+{
+	struct jz4780_dma_desc *desc = to_jz4780_dma_desc(vdesc);
+	struct jz4780_dma_chan *jzchan = to_jz4780_dma_chan(vdesc->tx.chan);
+
+	dma_pool_free(jzchan->desc_pool, desc->desc, desc->desc_phys);
+	kfree(desc);
+}
+
+static uint32_t jz4780_dma_transfer_size(unsigned long val, int *ord)
+{
+	*ord = ffs(val) - 1;
+
+	switch (*ord) {
+	case 0:
+		return JZ_DMA_SIZE_1_BYTE;
+	case 1:
+		return JZ_DMA_SIZE_2_BYTE;
+	case 2:
+		return JZ_DMA_SIZE_4_BYTE;
+	case 4:
+		return JZ_DMA_SIZE_16_BYTE;
+	case 5:
+		return JZ_DMA_SIZE_32_BYTE;
+	case 6:
+		return JZ_DMA_SIZE_64_BYTE;
+	case 7:
+		return JZ_DMA_SIZE_128_BYTE;
+	default:
+		return -EINVAL;
+	}
+}
+
+static uint32_t jz4780_dma_setup_hwdesc(struct jz4780_dma_chan *jzchan,
+	struct jz4780_dma_hwdesc *desc, dma_addr_t addr, size_t len,
+	enum dma_transfer_direction direction)
+{
+	struct dma_slave_config *config = &jzchan->config;
+	uint32_t width, maxburst, tsz;
+	int ord;
+
+	if (direction == DMA_MEM_TO_DEV) {
+		desc->dcm = JZ_DMA_DCM_SAI;
+		desc->dsa = addr;
+		desc->dta = config->dst_addr;
+		desc->drt = jzchan->transfer_type;
+
+		width = config->dst_addr_width;
+		maxburst = config->dst_maxburst;
+	} else {
+		desc->dcm = JZ_DMA_DCM_DAI;
+		desc->dsa = config->src_addr;
+		desc->dta = addr;
+		desc->drt = jzchan->transfer_type;
+
+		width = config->src_addr_width;
+		maxburst = config->src_maxburst;
+	}
+
+	/*
+	 * This calculates the maximum transfer size that can be used with the
+	 * given address, length, width and maximum burst size. The address
+	 * must be aligned to the transfer size, the total length must be
+	 * divisible by the transfer size, and we must not use more than the
+	 * maximum burst specified by the user.
+	 */
+	tsz = jz4780_dma_transfer_size(addr | len | (width * maxburst), &ord);
+	jzchan->transfer_shift = ord;
+
+	switch (width) {
+	case DMA_SLAVE_BUSWIDTH_1_BYTE:
+	case DMA_SLAVE_BUSWIDTH_2_BYTES:
+		break;
+	case DMA_SLAVE_BUSWIDTH_4_BYTES:
+		width = JZ_DMA_WIDTH_32_BIT;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	desc->dcm |= tsz << JZ_DMA_DCM_TSZ_SHIFT;
+	desc->dcm |= width << JZ_DMA_DCM_SP_SHIFT;
+	desc->dcm |= width << JZ_DMA_DCM_DP_SHIFT;
+
+	desc->dtc = len >> ord;
+}
+
+static struct dma_async_tx_descriptor *jz4780_dma_prep_slave_sg(
+	struct dma_chan *chan, struct scatterlist *sgl, unsigned int sg_len,
+	enum dma_transfer_direction direction, unsigned long flags)
+{
+	struct jz4780_dma_chan *jzchan = to_jz4780_dma_chan(chan);
+	struct jz4780_dma_desc *desc;
+	unsigned int i;
+	int err;
+
+	desc = jz4780_dma_desc_alloc(jzchan, sg_len, DMA_SLAVE);
+	if (!desc)
+		return NULL;
+
+	for (i = 0; i < sg_len; i++) {
+		err = jz4780_dma_setup_hwdesc(jzchan, &desc->desc[i],
+					sg_dma_address(&sgl[i]),
+					sg_dma_len(&sgl[i]),
+					direction);
+		if (err < 0)
+			return ERR_PTR(err);
+
+
+		desc->desc[i].dcm |= JZ_DMA_DCM_TIE;
+
+		if (i != (sg_len - 1)) {
+			/* Automatically proceeed to the next descriptor. */
+			desc->desc[i].dcm |= JZ_DMA_DCM_LINK;
+
+			/*
+			 * The upper 8 bits of the DTC field in the descriptor
+			 * must be set to (offset from descriptor base of next
+			 * descriptor >> 4).
+			 */
+			desc->desc[i].dtc |=
+				(((i + 1) * sizeof(*desc->desc)) >> 4) << 24;
+		}
+	}
+
+	return vchan_tx_prep(&jzchan->vchan, &desc->vdesc, flags);
+}
+
+static struct dma_async_tx_descriptor *jz4780_dma_prep_dma_cyclic(
+	struct dma_chan *chan, dma_addr_t buf_addr, size_t buf_len,
+	size_t period_len, enum dma_transfer_direction direction,
+	unsigned long flags)
+{
+	struct jz4780_dma_chan *jzchan = to_jz4780_dma_chan(chan);
+	struct jz4780_dma_desc *desc;
+	unsigned int periods, i;
+	int err;
+
+	if (buf_len % period_len)
+		return NULL;
+
+	periods = buf_len / period_len;
+
+	desc = jz4780_dma_desc_alloc(jzchan, periods, DMA_CYCLIC);
+	if (!desc)
+		return NULL;
+
+	for (i = 0; i < periods; i++) {
+		err = jz4780_dma_setup_hwdesc(jzchan, &desc->desc[i], buf_addr,
+					period_len, direction);
+		if (err < 0)
+			return ERR_PTR(err);
+
+		buf_addr += period_len;
+
+		/*
+		 * Set the link bit to indicate that the controller should
+		 * automatically proceed to the next descriptor. In
+		 * jz4780_dma_begin(), this will be cleared if we need to issue
+		 * an interrupt after each period.
+		 */
+		desc->desc[i].dcm |= JZ_DMA_DCM_TIE | JZ_DMA_DCM_LINK;
+
+		/*
+		 * The upper 8 bits of the DTC field in the descriptor must be
+		 * set to (offset from descriptor base of next descriptor >> 4).
+		 * If this is the last descriptor, link it back to the first,
+		 * i.e. leave offset set to 0, otherwise point to the next one.
+		 */
+		if (i != (periods - 1)) {
+			desc->desc[i].dtc |=
+				(((i + 1) * sizeof(*desc->desc)) >> 4) << 24;
+		}
+	}
+
+	return vchan_tx_prep(&jzchan->vchan, &desc->vdesc, flags);
+}
+
+struct dma_async_tx_descriptor *jz4780_dma_prep_dma_memcpy(
+	struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
+	size_t len, unsigned long flags)
+{
+	struct jz4780_dma_chan *jzchan = to_jz4780_dma_chan(chan);
+	struct jz4780_dma_desc *desc;
+	uint32_t tsz;
+	int ord;
+
+	desc = jz4780_dma_desc_alloc(jzchan, 1, DMA_MEMCPY);
+	if (!desc)
+		return NULL;
+
+	tsz = jz4780_dma_transfer_size(dest | src | len, &ord);
+	if (tsz < 0)
+		return ERR_PTR(tsz);
+
+	desc->desc[0].dsa = src;
+	desc->desc[0].dta = dest;
+	desc->desc[0].drt = JZ_DMA_DRT_AUTO;
+	desc->desc[0].dcm = JZ_DMA_DCM_TIE | JZ_DMA_DCM_SAI | JZ_DMA_DCM_DAI |
+			    tsz << JZ_DMA_DCM_TSZ_SHIFT |
+			    JZ_DMA_WIDTH_32_BIT << JZ_DMA_DCM_SP_SHIFT |
+			    JZ_DMA_WIDTH_32_BIT << JZ_DMA_DCM_DP_SHIFT;
+	desc->desc[0].dtc = len >> ord;
+
+	return vchan_tx_prep(&jzchan->vchan, &desc->vdesc, flags);
+}
+
+static void jz4780_dma_begin(struct jz4780_dma_chan *jzchan)
+{
+	struct jz4780_dma_dev *jzdma = jz4780_dma_chan_parent(jzchan);
+	struct virt_dma_desc *vdesc;
+	unsigned int i;
+	dma_addr_t desc_phys;
+
+	if (!jzchan->desc) {
+		vdesc = vchan_next_desc(&jzchan->vchan);
+		if (!vdesc)
+			return;
+
+		list_del(&vdesc->node);
+
+		jzchan->desc = to_jz4780_dma_desc(vdesc);
+		jzchan->curr_hwdesc = 0;
+
+		if (jzchan->desc->type == DMA_CYCLIC && vdesc->tx.callback) {
+			/*
+			 * The DMA controller doesn't support triggering an
+			 * interrupt after processing each descriptor, only
+			 * after processing an entire terminated list of
+			 * descriptors. For a cyclic DMA setup the list of
+			 * descriptors is not terminated so we can never get an
+			 * interrupt.
+			 *
+			 * If the user requested a callback for a cyclic DMA
+			 * setup then we workaround this hardware limitation
+			 * here by degrading to a set of unlinked descriptors
+			 * which we will submit in sequence in response to the
+			 * completion of processing the previous descriptor.
+			 */
+			for (i = 0; i < jzchan->desc->count; i++)
+				jzchan->desc->desc[i].dcm &= ~JZ_DMA_DCM_LINK;
+		}
+	} else {
+		/*
+		 * There is an existing transfer, therefore this must be one
+		 * for which we unlinked the descriptors above. Advance to the
+		 * next one in the list.
+		 */
+		jzchan->curr_hwdesc =
+			(jzchan->curr_hwdesc + 1) % jzchan->desc->count;
+	}
+
+	/* Use 8-word descriptors. */
+	jz4780_dma_writel(jzdma, JZ_DMA_REG_DCS(jzchan->id), JZ_DMA_DCS_DES8);
+
+	/* Write descriptor address and initiate descriptor fetch. */
+	desc_phys = jzchan->desc->desc_phys +
+		    (jzchan->curr_hwdesc * sizeof(*jzchan->desc->desc));
+	jz4780_dma_writel(jzdma, JZ_DMA_REG_DDA(jzchan->id), desc_phys);
+	jz4780_dma_writel(jzdma, JZ_DMA_REG_DDRS, BIT(jzchan->id));
+
+	/* Enable the channel. */
+	jz4780_dma_writel(jzdma, JZ_DMA_REG_DCS(jzchan->id),
+			  JZ_DMA_DCS_DES8 | JZ_DMA_DCS_CTE);
+}
+
+static void jz4780_dma_issue_pending(struct dma_chan *chan)
+{
+	struct jz4780_dma_chan *jzchan = to_jz4780_dma_chan(chan);
+	unsigned long flags;
+
+	spin_lock_irqsave(&jzchan->vchan.lock, flags);
+
+	if (vchan_issue_pending(&jzchan->vchan) && !jzchan->desc)
+		jz4780_dma_begin(jzchan);
+
+	spin_unlock_irqrestore(&jzchan->vchan.lock, flags);
+}
+
+static int jz4780_dma_terminate_all(struct jz4780_dma_chan *jzchan)
+{
+	struct jz4780_dma_dev *jzdma = jz4780_dma_chan_parent(jzchan);
+	unsigned long flags;
+	LIST_HEAD(head);
+
+	spin_lock_irqsave(&jzchan->vchan.lock, flags);
+
+	/* Clear the DMA status and stop the transfer. */
+	jz4780_dma_writel(jzdma, JZ_DMA_REG_DCS(jzchan->id), 0);
+	if (jzchan->desc) {
+		jz4780_dma_desc_free(&jzchan->desc->vdesc);
+		jzchan->desc = NULL;
+	}
+
+	vchan_get_all_descriptors(&jzchan->vchan, &head);
+
+	spin_unlock_irqrestore(&jzchan->vchan.lock, flags);
+
+	vchan_dma_desc_free_list(&jzchan->vchan, &head);
+	return 0;
+}
+
+static int jz4780_dma_slave_config(struct jz4780_dma_chan *jzchan,
+	const struct dma_slave_config *config)
+{
+	if ((config->src_addr_width == DMA_SLAVE_BUSWIDTH_8_BYTES)
+	   || (config->dst_addr_width == DMA_SLAVE_BUSWIDTH_8_BYTES))
+		return -EINVAL;
+
+	/* Copy the reset of the slave configuration, it is used later. */
+	memcpy(&jzchan->config, config, sizeof(jzchan->config));
+
+	return 0;
+}
+
+static size_t jz4780_dma_desc_residue(struct jz4780_dma_chan *jzchan,
+	struct jz4780_dma_desc *desc, unsigned int next_sg)
+{
+	struct jz4780_dma_dev *jzdma = jz4780_dma_chan_parent(jzchan);
+	unsigned int residue, count;
+	unsigned int i;
+
+	residue = 0;
+
+	for (i = next_sg; i < desc->count; i++)
+		residue += desc->desc[i].dtc << jzchan->transfer_shift;
+
+	if (next_sg != 0) {
+		count = jz4780_dma_readl(jzdma,
+					 JZ_DMA_REG_DTC(jzchan->id));
+		residue += count << jzchan->transfer_shift;
+	}
+
+	return residue;
+}
+
+static enum dma_status jz4780_dma_tx_status(struct dma_chan *chan,
+	dma_cookie_t cookie, struct dma_tx_state *txstate)
+{
+	struct jz4780_dma_chan *jzchan = to_jz4780_dma_chan(chan);
+	struct virt_dma_desc *vdesc;
+	enum dma_status status;
+	unsigned long flags;
+
+	status = dma_cookie_status(chan, cookie, txstate);
+	if ((status == DMA_COMPLETE) || (txstate == NULL))
+		return status;
+
+	spin_lock_irqsave(&jzchan->vchan.lock, flags);
+
+	vdesc = vchan_find_desc(&jzchan->vchan, cookie);
+	if (vdesc) {
+		/* On the issued list, so hasn't been processed yet */
+		txstate->residue = jz4780_dma_desc_residue(jzchan,
+					to_jz4780_dma_desc(vdesc), 0);
+	} else if (cookie == jzchan->desc->vdesc.tx.cookie) {
+		txstate->residue = jz4780_dma_desc_residue(jzchan, jzchan->desc,
+			  (jzchan->curr_hwdesc + 1) % jzchan->desc->count);
+	} else
+		txstate->residue = 0;
+
+	if (vdesc && jzchan->desc && vdesc == &jzchan->desc->vdesc
+		&& jzchan->desc->status & (JZ_DMA_DCS_AR | JZ_DMA_DCS_HLT))
+			status = DMA_ERROR;
+
+	spin_unlock_irqrestore(&jzchan->vchan.lock, flags);
+	return status;
+}
+
+static void jz4780_dma_chan_irq(struct jz4780_dma_dev *jzdma,
+	struct jz4780_dma_chan *jzchan)
+{
+	uint32_t dcs;
+
+	spin_lock(&jzchan->vchan.lock);
+
+	dcs = jz4780_dma_readl(jzdma, JZ_DMA_REG_DCS(jzchan->id));
+	jz4780_dma_writel(jzdma, JZ_DMA_REG_DCS(jzchan->id), 0);
+
+	if (dcs & JZ_DMA_DCS_AR) {
+		dev_warn(&jzchan->vchan.chan.dev->device,
+			 "address error (DCS=0x%x)\n", dcs);
+	}
+
+	if (dcs & JZ_DMA_DCS_HLT) {
+		dev_warn(&jzchan->vchan.chan.dev->device,
+			 "channel halt (DCS=0x%x)\n", dcs);
+	}
+
+	if (jzchan->desc) {
+		jzchan->desc->status = dcs;
+
+		if ((dcs & (JZ_DMA_DCS_AR | JZ_DMA_DCS_HLT)) == 0) {
+			if (jzchan->desc->type == DMA_CYCLIC) {
+				vchan_cyclic_callback(&jzchan->desc->vdesc);
+			} else {
+				vchan_cookie_complete(&jzchan->desc->vdesc);
+				jzchan->desc = NULL;
+			}
+
+			jz4780_dma_begin(jzchan);
+		}
+	} else {
+		dev_err(&jzchan->vchan.chan.dev->device,
+			"channel IRQ with no active transfer\n");
+	}
+
+	spin_unlock(&jzchan->vchan.lock);
+}
+
+static irqreturn_t jz4780_dma_irq_handler(int irq, void *data)
+{
+	struct jz4780_dma_dev *jzdma = data;
+	uint32_t pending, dmac;
+	int i;
+
+	pending = jz4780_dma_readl(jzdma, JZ_DMA_REG_DIRQP);
+
+	for (i = 0; i < JZ_DMA_NR_CHANNELS; i++) {
+		if (!(pending & (1<<i)))
+			continue;
+
+		jz4780_dma_chan_irq(jzdma, &jzdma->chan[i]);
+	}
+
+	/* Clear halt and address error status of all channels. */
+	dmac = jz4780_dma_readl(jzdma, JZ_DMA_REG_DMAC);
+	dmac &= ~(JZ_DMA_DMAC_HLT | JZ_DMA_DMAC_AR);
+	jz4780_dma_writel(jzdma, JZ_DMA_REG_DMAC, dmac);
+
+	/* Clear interrupt pending status. */
+	jz4780_dma_writel(jzdma, JZ_DMA_REG_DIRQP, 0);
+
+	return IRQ_HANDLED;
+}
+
+static int jz4780_dma_alloc_chan_resources(struct dma_chan *chan)
+{
+	struct jz4780_dma_chan *jzchan = to_jz4780_dma_chan(chan);
+
+	jzchan->desc_pool = dma_pool_create(dev_name(&chan->dev->device),
+					    chan->device->dev,
+					    JZ_DMA_DESC_BLOCK_SIZE,
+					    PAGE_SIZE, 0);
+	if (!jzchan->desc_pool) {
+		dev_err(&chan->dev->device,
+			"failed to allocate descriptor pool\n");
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+static void jz4780_dma_free_chan_resources(struct dma_chan *chan)
+{
+	struct jz4780_dma_chan *jzchan = to_jz4780_dma_chan(chan);
+
+	vchan_free_chan_resources(&jzchan->vchan);
+	dma_pool_destroy(jzchan->desc_pool);
+	jzchan->desc_pool = NULL;
+}
+
+static bool jz4780_dma_filter_fn(struct dma_chan *chan, void *param)
+{
+	struct jz4780_dma_chan *jzchan = to_jz4780_dma_chan(chan);
+	struct jz4780_dma_dev *jzdma = jz4780_dma_chan_parent(jzchan);
+	struct jz4780_dma_data *data = param;
+
+	if (data->channel > -1) {
+		if (data->channel != jzchan->id)
+			return false;
+	} else if (jzdma->chan_reserved & BIT(jzchan->id)) {
+		return false;
+	}
+
+	jzchan->transfer_type = data->transfer_type;
+
+	return true;
+}
+
+static struct dma_chan *jz4780_of_dma_xlate(struct of_phandle_args *dma_spec,
+	struct of_dma *ofdma)
+{
+	struct jz4780_dma_dev *jzdma = ofdma->of_dma_data;
+	dma_cap_mask_t mask = jzdma->dma_device.cap_mask;
+	struct jz4780_dma_data data;
+
+	if (dma_spec->args_count != 2)
+		return NULL;
+
+	data.transfer_type = dma_spec->args[0];
+	data.channel = dma_spec->args[1];
+
+	if (data.channel > -1) {
+		if (data.channel >= JZ_DMA_NR_CHANNELS) {
+			dev_err(jzdma->dma_device.dev,
+				"device requested non-existent channel %u\n",
+				data.channel);
+			return NULL;
+		}
+
+		/* Can only select a channel marked as reserved. */
+		if (!(jzdma->chan_reserved & BIT(data.channel))) {
+			dev_err(jzdma->dma_device.dev,
+				"device requested unreserved channel %u\n",
+				data.channel);
+			return NULL;
+		}
+	}
+
+	return dma_request_channel(mask, jz4780_dma_filter_fn, &data);
+}
+
+static int jz4780_dma_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct jz4780_dma_dev *jzdma;
+	struct jz4780_dma_chan *jzchan;
+	struct dma_device *dd;
+	struct resource *res;
+	int i, ret;
+
+	jzdma = devm_kzalloc(dev, sizeof(*jzdma), GFP_KERNEL);
+	if (!jzdma)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, jzdma);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		dev_err(dev, "failed to get I/O memory\n");
+		return -EINVAL;
+	}
+
+	jzdma->base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(jzdma->base))
+		return PTR_ERR(jzdma->base);
+
+	jzdma->irq = platform_get_irq(pdev, 0);
+	if (jzdma->irq < 0) {
+		dev_err(dev, "failed to get IRQ: %d\n", ret);
+		return jzdma->irq;
+	}
+
+	ret = devm_request_irq(dev, jzdma->irq, jz4780_dma_irq_handler, 0,
+			       dev_name(dev), jzdma);
+	if (ret) {
+		dev_err(dev, "failed to request IRQ %u!\n", jzdma->irq);
+		return -EINVAL;
+	}
+
+	jzdma->clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(jzdma->clk)) {
+		dev_err(dev, "failed to get clock\n");
+		return PTR_ERR(jzdma->clk);
+	}
+
+	clk_prepare_enable(jzdma->clk);
+
+	/* Property is optional, if it doesn't exist the value will remain 0. */
+	of_property_read_u32_index(dev->of_node, "ingenic,reserved-channels",
+				   0, &jzdma->chan_reserved);
+
+	dd = &jzdma->dma_device;
+
+	dma_cap_set(DMA_MEMCPY, dd->cap_mask);
+	dma_cap_set(DMA_SLAVE, dd->cap_mask);
+	dma_cap_set(DMA_CYCLIC, dd->cap_mask);
+
+	dd->dev = dev;
+	dd->copy_align = 2; /* 2^2 = 4 byte alignment */
+	dd->device_alloc_chan_resources = jz4780_dma_alloc_chan_resources;
+	dd->device_free_chan_resources = jz4780_dma_free_chan_resources;
+	dd->device_prep_slave_sg = jz4780_dma_prep_slave_sg;
+	dd->device_prep_dma_cyclic = jz4780_dma_prep_dma_cyclic;
+	dd->device_prep_dma_memcpy = jz4780_dma_prep_dma_memcpy;
+	dd->device_config = jz4780_dma_slave_config;
+	dd->device_terminate_all = jz4780_dma_terminate_all;
+	dd->device_tx_status = jz4780_dma_tx_status;
+	dd->device_issue_pending = jz4780_dma_issue_pending;
+	dd->src_addr_widths = JZ_DMA_BUSWIDTHS;
+	dd->dst_addr_widths = JZ_DMA_BUSWIDTHS;
+	dd->directions = BIT(DMA_DEV_TO_MEM) | BIT(DMA_MEM_TO_DEV);
+	dd->residue_granularity = DMA_RESIDUE_GRANULARITY_BURST;
+
+
+	/*
+	 * Enable DMA controller, mark all channels as not programmable.
+	 * Also set the FMSC bit - it increases MSC performance, so it makes
+	 * little sense not to enable it.
+	 */
+	jz4780_dma_writel(jzdma, JZ_DMA_REG_DMAC,
+			  JZ_DMA_DMAC_DMAE | JZ_DMA_DMAC_FMSC);
+	jz4780_dma_writel(jzdma, JZ_DMA_REG_DMACP, 0);
+
+	INIT_LIST_HEAD(&dd->channels);
+
+	for (i = 0; i < JZ_DMA_NR_CHANNELS; i++) {
+		jzchan = &jzdma->chan[i];
+		jzchan->id = i;
+
+		vchan_init(&jzchan->vchan, dd);
+		jzchan->vchan.desc_free = jz4780_dma_desc_free;
+	}
+
+	ret = dma_async_device_register(dd);
+	if (ret) {
+		dev_err(dev, "failed to register device\n");
+		goto err_disable_clk;
+	}
+
+	/* Register with OF DMA helpers. */
+	ret = of_dma_controller_register(dev->of_node, jz4780_of_dma_xlate,
+					 jzdma);
+	if (ret) {
+		dev_err(dev, "failed to register OF DMA controller\n");
+		goto err_unregister_dev;
+	}
+
+	dev_info(dev, "JZ4780 DMA controller initialised\n");
+	return 0;
+
+err_unregister_dev:
+	dma_async_device_unregister(dd);
+
+err_disable_clk:
+	clk_disable_unprepare(jzdma->clk);
+	return ret;
+}
+
+static int jz4780_dma_remove(struct platform_device *pdev)
+{
+	struct jz4780_dma_dev *jzdma = platform_get_drvdata(pdev);
+
+	of_dma_controller_free(pdev->dev.of_node);
+	devm_free_irq(&pdev->dev, jzdma->irq, jzdma);
+	dma_async_device_unregister(&jzdma->dma_device);
+	return 0;
+}
+
+static const struct of_device_id jz4780_dma_dt_match[] = {
+	{ .compatible = "ingenic,jz4780-dma", .data = NULL },
+	{},
+};
+MODULE_DEVICE_TABLE(of, jz4780_dma_dt_match);
+
+static struct platform_driver jz4780_dma_driver = {
+	.probe		= jz4780_dma_probe,
+	.remove		= jz4780_dma_remove,
+	.driver	= {
+		.name	= "jz4780-dma",
+		.of_match_table = of_match_ptr(jz4780_dma_dt_match),
+	},
+};
+
+static int __init jz4780_dma_init(void)
+{
+	return platform_driver_register(&jz4780_dma_driver);
+}
+subsys_initcall(jz4780_dma_init);
+
+static void __exit jz4780_dma_exit(void)
+{
+	platform_driver_unregister(&jz4780_dma_driver);
+}
+module_exit(jz4780_dma_exit);
+
+MODULE_AUTHOR("Alex Smith <alex@alex-smith.me.uk>");
+MODULE_DESCRIPTION("Ingenic JZ4780 DMA controller driver");
+MODULE_LICENSE("GPL");