dmaengine: sun4i: Add support for the DMA engine on sun[457]i SoCs

This patch adds support for the DMA engine present on Allwinner A10,
A13, A10S and A20 SoCs. This engine has two kinds of channels: normal
and dedicated. The main difference is in the mode of operation;
while a single normal channel may be operating at any given time,
dedicated channels may operate simultaneously provided there is no
overlap of source or destination.

Hardware documentation can be found on A10 User Manual (section 12), A13
User Manual (section 14) and A20 User Manual (section 1.12)

Signed-off-by: Emilio López <emilio@elopez.com.ar>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

3 files changed, 1300 insertions, 0 deletions

diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
index 9d5a77cb9715..5244b44f5e67 100644
--- a/drivers/dma/Kconfig
+++ b/drivers/dma/Kconfig
@@ -434,6 +434,17 @@ config XILINX_VDMA
 	  channels, Memory Mapped to Stream (MM2S) and Stream to
 	  Memory Mapped (S2MM) for the data transfers.
 
+config DMA_SUN4I
+	tristate "Allwinner A10 DMA SoCs support"
+	depends on MACH_SUN4I || MACH_SUN5I || MACH_SUN7I || COMPILE_TEST
+	default (MACH_SUN4I || MACH_SUN5I || MACH_SUN7I)
+	select DMA_ENGINE
+	select DMA_OF
+	select DMA_VIRTUAL_CHANNELS
+	help
+	  Enable support for the DMA controller present in the sun4i,
+	  sun5i and sun7i Allwinner ARM SoCs.
+
 config DMA_SUN6I
 	tristate "Allwinner A31 SoCs DMA support"
 	depends on MACH_SUN6I || MACH_SUN8I || COMPILE_TEST
diff --git a/drivers/dma/Makefile b/drivers/dma/Makefile
index 800cb2d20be8..e707ff956164 100644
--- a/drivers/dma/Makefile
+++ b/drivers/dma/Makefile
@@ -55,5 +55,6 @@ obj-y += xilinx/
 obj-$(CONFIG_INTEL_MIC_X100_DMA) += mic_x100_dma.o
 obj-$(CONFIG_NBPFAXI_DMA) += nbpfaxi.o
 obj-$(CONFIG_DMA_SUN6I) += sun6i-dma.o
+obj-$(CONFIG_DMA_SUN4I) += sun4i-dma.o
 obj-$(CONFIG_IMG_MDC_DMA) += img-mdc-dma.o
 obj-$(CONFIG_XGENE_DMA) += xgene-dma.o
diff --git a/drivers/dma/sun4i-dma.c b/drivers/dma/sun4i-dma.c
new file mode 100644
index 000000000000..a1a500d96ff2
--- /dev/null
+++ b/drivers/dma/sun4i-dma.c
@@ -0,0 +1,1288 @@
+/*
+ * Copyright (C) 2014 Emilio López
+ * Emilio López <emilio@elopez.com.ar>
+ *
+ * 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/bitmap.h>
+#include <linux/bitops.h>
+#include <linux/clk.h>
+#include <linux/dmaengine.h>
+#include <linux/dmapool.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/of_dma.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+
+#include "virt-dma.h"
+
+/** Common macros to normal and dedicated DMA registers **/
+
+#define SUN4I_DMA_CFG_LOADING			BIT(31)
+#define SUN4I_DMA_CFG_DST_DATA_WIDTH(width)	((width) << 25)
+#define SUN4I_DMA_CFG_DST_BURST_LENGTH(len)	((len) << 23)
+#define SUN4I_DMA_CFG_DST_ADDR_MODE(mode)	((mode) << 21)
+#define SUN4I_DMA_CFG_DST_DRQ_TYPE(type)	((type) << 16)
+#define SUN4I_DMA_CFG_SRC_DATA_WIDTH(width)	((width) << 9)
+#define SUN4I_DMA_CFG_SRC_BURST_LENGTH(len)	((len) << 7)
+#define SUN4I_DMA_CFG_SRC_ADDR_MODE(mode)	((mode) << 5)
+#define SUN4I_DMA_CFG_SRC_DRQ_TYPE(type)	(type)
+
+/** Normal DMA register values **/
+
+/* Normal DMA source/destination data request type values */
+#define SUN4I_NDMA_DRQ_TYPE_SDRAM		0x16
+#define SUN4I_NDMA_DRQ_TYPE_LIMIT		(0x1F + 1)
+
+/** Normal DMA register layout **/
+
+/* Dedicated DMA source/destination address mode values */
+#define SUN4I_NDMA_ADDR_MODE_LINEAR		0
+#define SUN4I_NDMA_ADDR_MODE_IO			1
+
+/* Normal DMA configuration register layout */
+#define SUN4I_NDMA_CFG_CONT_MODE		BIT(30)
+#define SUN4I_NDMA_CFG_WAIT_STATE(n)		((n) << 27)
+#define SUN4I_NDMA_CFG_DST_NON_SECURE		BIT(22)
+#define SUN4I_NDMA_CFG_BYTE_COUNT_MODE_REMAIN	BIT(15)
+#define SUN4I_NDMA_CFG_SRC_NON_SECURE		BIT(6)
+
+/** Dedicated DMA register values **/
+
+/* Dedicated DMA source/destination address mode values */
+#define SUN4I_DDMA_ADDR_MODE_LINEAR		0
+#define SUN4I_DDMA_ADDR_MODE_IO			1
+#define SUN4I_DDMA_ADDR_MODE_HORIZONTAL_PAGE	2
+#define SUN4I_DDMA_ADDR_MODE_VERTICAL_PAGE	3
+
+/* Dedicated DMA source/destination data request type values */
+#define SUN4I_DDMA_DRQ_TYPE_SDRAM		0x1
+#define SUN4I_DDMA_DRQ_TYPE_LIMIT		(0x1F + 1)
+
+/** Dedicated DMA register layout **/
+
+/* Dedicated DMA configuration register layout */
+#define SUN4I_DDMA_CFG_BUSY			BIT(30)
+#define SUN4I_DDMA_CFG_CONT_MODE		BIT(29)
+#define SUN4I_DDMA_CFG_DST_NON_SECURE		BIT(28)
+#define SUN4I_DDMA_CFG_BYTE_COUNT_MODE_REMAIN	BIT(15)
+#define SUN4I_DDMA_CFG_SRC_NON_SECURE		BIT(12)
+
+/* Dedicated DMA parameter register layout */
+#define SUN4I_DDMA_PARA_DST_DATA_BLK_SIZE(n)	(((n) - 1) << 24)
+#define SUN4I_DDMA_PARA_DST_WAIT_CYCLES(n)	(((n) - 1) << 16)
+#define SUN4I_DDMA_PARA_SRC_DATA_BLK_SIZE(n)	(((n) - 1) << 8)
+#define SUN4I_DDMA_PARA_SRC_WAIT_CYCLES(n)	(((n) - 1) << 0)
+
+/** DMA register offsets **/
+
+/* General register offsets */
+#define SUN4I_DMA_IRQ_ENABLE_REG		0x0
+#define SUN4I_DMA_IRQ_PENDING_STATUS_REG	0x4
+
+/* Normal DMA register offsets */
+#define SUN4I_NDMA_CHANNEL_REG_BASE(n)		(0x100 + (n) * 0x20)
+#define SUN4I_NDMA_CFG_REG			0x0
+#define SUN4I_NDMA_SRC_ADDR_REG			0x4
+#define SUN4I_NDMA_DST_ADDR_REG		0x8
+#define SUN4I_NDMA_BYTE_COUNT_REG		0xC
+
+/* Dedicated DMA register offsets */
+#define SUN4I_DDMA_CHANNEL_REG_BASE(n)		(0x300 + (n) * 0x20)
+#define SUN4I_DDMA_CFG_REG			0x0
+#define SUN4I_DDMA_SRC_ADDR_REG			0x4
+#define SUN4I_DDMA_DST_ADDR_REG		0x8
+#define SUN4I_DDMA_BYTE_COUNT_REG		0xC
+#define SUN4I_DDMA_PARA_REG			0x18
+
+/** DMA Driver **/
+
+/*
+ * Normal DMA has 8 channels, and Dedicated DMA has another 8, so
+ * that's 16 channels. As for endpoints, there's 29 and 21
+ * respectively. Given that the Normal DMA endpoints (other than
+ * SDRAM) can be used as tx/rx, we need 78 vchans in total
+ */
+#define SUN4I_NDMA_NR_MAX_CHANNELS	8
+#define SUN4I_DDMA_NR_MAX_CHANNELS	8
+#define SUN4I_DMA_NR_MAX_CHANNELS					\
+	(SUN4I_NDMA_NR_MAX_CHANNELS + SUN4I_DDMA_NR_MAX_CHANNELS)
+#define SUN4I_NDMA_NR_MAX_VCHANS	(29 * 2 - 1)
+#define SUN4I_DDMA_NR_MAX_VCHANS	21
+#define SUN4I_DMA_NR_MAX_VCHANS						\
+	(SUN4I_NDMA_NR_MAX_VCHANS + SUN4I_DDMA_NR_MAX_VCHANS)
+
+/* This set of SUN4I_DDMA timing parameters were found experimentally while
+ * working with the SPI driver and seem to make it behave correctly */
+#define SUN4I_DDMA_MAGIC_SPI_PARAMETERS \
+	(SUN4I_DDMA_PARA_DST_DATA_BLK_SIZE(1) |			\
+	 SUN4I_DDMA_PARA_SRC_DATA_BLK_SIZE(1) |				\
+	 SUN4I_DDMA_PARA_DST_WAIT_CYCLES(2) |				\
+	 SUN4I_DDMA_PARA_SRC_WAIT_CYCLES(2))
+
+struct sun4i_dma_pchan {
+	/* Register base of channel */
+	void __iomem			*base;
+	/* vchan currently being serviced */
+	struct sun4i_dma_vchan		*vchan;
+	/* Is this a dedicated pchan? */
+	int				is_dedicated;
+};
+
+struct sun4i_dma_vchan {
+	struct virt_dma_chan		vc;
+	struct dma_slave_config		cfg;
+	struct sun4i_dma_pchan		*pchan;
+	struct sun4i_dma_promise	*processing;
+	struct sun4i_dma_contract	*contract;
+	u8				endpoint;
+	int				is_dedicated;
+};
+
+struct sun4i_dma_promise {
+	u32				cfg;
+	u32				para;
+	dma_addr_t			src;
+	dma_addr_t			dst;
+	size_t				len;
+	struct list_head		list;
+};
+
+/* A contract is a set of promises */
+struct sun4i_dma_contract {
+	struct virt_dma_desc		vd;
+	struct list_head		demands;
+	struct list_head		completed_demands;
+	int				is_cyclic;
+};
+
+struct sun4i_dma_dev {
+	DECLARE_BITMAP(pchans_used, SUN4I_DMA_NR_MAX_CHANNELS);
+	struct dma_device		slave;
+	struct sun4i_dma_pchan		*pchans;
+	struct sun4i_dma_vchan		*vchans;
+	void __iomem			*base;
+	struct clk			*clk;
+	int				irq;
+	spinlock_t			lock;
+};
+
+static struct sun4i_dma_dev *to_sun4i_dma_dev(struct dma_device *dev)
+{
+	return container_of(dev, struct sun4i_dma_dev, slave);
+}
+
+static struct sun4i_dma_vchan *to_sun4i_dma_vchan(struct dma_chan *chan)
+{
+	return container_of(chan, struct sun4i_dma_vchan, vc.chan);
+}
+
+static struct sun4i_dma_contract *to_sun4i_dma_contract(struct virt_dma_desc *vd)
+{
+	return container_of(vd, struct sun4i_dma_contract, vd);
+}
+
+static struct device *chan2dev(struct dma_chan *chan)
+{
+	return &chan->dev->device;
+}
+
+static int convert_burst(u32 maxburst)
+{
+	if (maxburst > 8)
+		return -EINVAL;
+
+	/* 1 -> 0, 4 -> 1, 8 -> 2 */
+	return (maxburst >> 2);
+}
+
+static int convert_buswidth(enum dma_slave_buswidth addr_width)
+{
+	if (addr_width > DMA_SLAVE_BUSWIDTH_4_BYTES)
+		return -EINVAL;
+
+	/* 8 (1 byte) -> 0, 16 (2 bytes) -> 1, 32 (4 bytes) -> 2 */
+	return (addr_width >> 1);
+}
+
+static void sun4i_dma_free_chan_resources(struct dma_chan *chan)
+{
+	struct sun4i_dma_vchan *vchan = to_sun4i_dma_vchan(chan);
+
+	vchan_free_chan_resources(&vchan->vc);
+}
+
+static struct sun4i_dma_pchan *find_and_use_pchan(struct sun4i_dma_dev *priv,
+						  struct sun4i_dma_vchan *vchan)
+{
+	struct sun4i_dma_pchan *pchan = NULL, *pchans = priv->pchans;
+	unsigned long flags;
+	int i, max;
+
+	/*
+	 * pchans 0-SUN4I_NDMA_NR_MAX_CHANNELS are normal, and
+	 * SUN4I_NDMA_NR_MAX_CHANNELS+ are dedicated ones
+	 */
+	if (vchan->is_dedicated) {
+		i = SUN4I_NDMA_NR_MAX_CHANNELS;
+		max = SUN4I_DMA_NR_MAX_CHANNELS;
+	} else {
+		i = 0;
+		max = SUN4I_NDMA_NR_MAX_CHANNELS;
+	}
+
+	spin_lock_irqsave(&priv->lock, flags);
+	for_each_clear_bit_from(i, &priv->pchans_used, max) {
+		pchan = &pchans[i];
+		pchan->vchan = vchan;
+		set_bit(i, priv->pchans_used);
+		break;
+	}
+	spin_unlock_irqrestore(&priv->lock, flags);
+
+	return pchan;
+}
+
+static void release_pchan(struct sun4i_dma_dev *priv,
+			  struct sun4i_dma_pchan *pchan)
+{
+	unsigned long flags;
+	int nr = pchan - priv->pchans;
+
+	spin_lock_irqsave(&priv->lock, flags);
+
+	pchan->vchan = NULL;
+	clear_bit(nr, priv->pchans_used);
+
+	spin_unlock_irqrestore(&priv->lock, flags);
+}
+
+static void configure_pchan(struct sun4i_dma_pchan *pchan,
+			    struct sun4i_dma_promise *d)
+{
+	/*
+	 * Configure addresses and misc parameters depending on type
+	 * SUN4I_DDMA has an extra field with timing parameters
+	 */
+	if (pchan->is_dedicated) {
+		writel_relaxed(d->src, pchan->base + SUN4I_DDMA_SRC_ADDR_REG);
+		writel_relaxed(d->dst, pchan->base + SUN4I_DDMA_DST_ADDR_REG);
+		writel_relaxed(d->len, pchan->base + SUN4I_DDMA_BYTE_COUNT_REG);
+		writel_relaxed(d->para, pchan->base + SUN4I_DDMA_PARA_REG);
+		writel_relaxed(d->cfg, pchan->base + SUN4I_DDMA_CFG_REG);
+	} else {
+		writel_relaxed(d->src, pchan->base + SUN4I_NDMA_SRC_ADDR_REG);
+		writel_relaxed(d->dst, pchan->base + SUN4I_NDMA_DST_ADDR_REG);
+		writel_relaxed(d->len, pchan->base + SUN4I_NDMA_BYTE_COUNT_REG);
+		writel_relaxed(d->cfg, pchan->base + SUN4I_NDMA_CFG_REG);
+	}
+}
+
+static void set_pchan_interrupt(struct sun4i_dma_dev *priv,
+				struct sun4i_dma_pchan *pchan,
+				int half, int end)
+{
+	u32 reg;
+	int pchan_number = pchan - priv->pchans;
+	unsigned long flags;
+
+	spin_lock_irqsave(&priv->lock, flags);
+
+	reg = readl_relaxed(priv->base + SUN4I_DMA_IRQ_ENABLE_REG);
+
+	if (half)
+		reg |= BIT(pchan_number * 2);
+	else
+		reg &= ~BIT(pchan_number * 2);
+
+	if (end)
+		reg |= BIT(pchan_number * 2 + 1);
+	else
+		reg &= ~BIT(pchan_number * 2 + 1);
+
+	writel_relaxed(reg, priv->base + SUN4I_DMA_IRQ_ENABLE_REG);
+
+	spin_unlock_irqrestore(&priv->lock, flags);
+}
+
+/**
+ * Execute pending operations on a vchan
+ *
+ * When given a vchan, this function will try to acquire a suitable
+ * pchan and, if successful, will configure it to fulfill a promise
+ * from the next pending contract.
+ *
+ * This function must be called with &vchan->vc.lock held.
+ */
+static int __execute_vchan_pending(struct sun4i_dma_dev *priv,
+				   struct sun4i_dma_vchan *vchan)
+{
+	struct sun4i_dma_promise *promise = NULL;
+	struct sun4i_dma_contract *contract = NULL;
+	struct sun4i_dma_pchan *pchan;
+	struct virt_dma_desc *vd;
+	int ret;
+
+	lockdep_assert_held(&vchan->vc.lock);
+
+	/* We need a pchan to do anything, so secure one if available */
+	pchan = find_and_use_pchan(priv, vchan);
+	if (!pchan)
+		return -EBUSY;
+
+	/*
+	 * Channel endpoints must not be repeated, so if this vchan
+	 * has already submitted some work, we can't do anything else
+	 */
+	if (vchan->processing) {
+		dev_dbg(chan2dev(&vchan->vc.chan),
+			"processing something to this endpoint already\n");
+		ret = -EBUSY;
+		goto release_pchan;
+	}
+
+	do {
+		/* Figure out which contract we're working with today */
+		vd = vchan_next_desc(&vchan->vc);
+		if (!vd) {
+			dev_dbg(chan2dev(&vchan->vc.chan),
+				"No pending contract found");
+			ret = 0;
+			goto release_pchan;
+		}
+
+		contract = to_sun4i_dma_contract(vd);
+		if (list_empty(&contract->demands)) {
+			/* The contract has been completed so mark it as such */
+			list_del(&contract->vd.node);
+			vchan_cookie_complete(&contract->vd);
+			dev_dbg(chan2dev(&vchan->vc.chan),
+				"Empty contract found and marked complete");
+		}
+	} while (list_empty(&contract->demands));
+
+	/* Now find out what we need to do */
+	promise = list_first_entry(&contract->demands,
+				   struct sun4i_dma_promise, list);
+	vchan->processing = promise;
+
+	/* ... and make it reality */
+	if (promise) {
+		vchan->contract = contract;
+		vchan->pchan = pchan;
+		set_pchan_interrupt(priv, pchan, contract->is_cyclic, 1);
+		configure_pchan(pchan, promise);
+	}
+
+	return 0;
+
+release_pchan:
+	release_pchan(priv, pchan);
+	return ret;
+}
+
+static int sanitize_config(struct dma_slave_config *sconfig,
+			   enum dma_transfer_direction direction)
+{
+	switch (direction) {
+	case DMA_MEM_TO_DEV:
+		if ((sconfig->dst_addr_width == DMA_SLAVE_BUSWIDTH_UNDEFINED) ||
+		    !sconfig->dst_maxburst)
+			return -EINVAL;
+
+		if (sconfig->src_addr_width == DMA_SLAVE_BUSWIDTH_UNDEFINED)
+			sconfig->src_addr_width = sconfig->dst_addr_width;
+
+		if (!sconfig->src_maxburst)
+			sconfig->src_maxburst = sconfig->dst_maxburst;
+
+		break;
+
+	case DMA_DEV_TO_MEM:
+		if ((sconfig->src_addr_width == DMA_SLAVE_BUSWIDTH_UNDEFINED) ||
+		    !sconfig->src_maxburst)
+			return -EINVAL;
+
+		if (sconfig->dst_addr_width == DMA_SLAVE_BUSWIDTH_UNDEFINED)
+			sconfig->dst_addr_width = sconfig->src_addr_width;
+
+		if (!sconfig->dst_maxburst)
+			sconfig->dst_maxburst = sconfig->src_maxburst;
+
+		break;
+	default:
+		return 0;
+	}
+
+	return 0;
+}
+
+/**
+ * Generate a promise, to be used in a normal DMA contract.
+ *
+ * A NDMA promise contains all the information required to program the
+ * normal part of the DMA Engine and get data copied. A non-executed
+ * promise will live in the demands list on a contract. Once it has been
+ * completed, it will be moved to the completed demands list for later freeing.
+ * All linked promises will be freed when the corresponding contract is freed
+ */
+static struct sun4i_dma_promise *
+generate_ndma_promise(struct dma_chan *chan, dma_addr_t src, dma_addr_t dest,
+		      size_t len, struct dma_slave_config *sconfig,
+		      enum dma_transfer_direction direction)
+{
+	struct sun4i_dma_promise *promise;
+	int ret;
+
+	ret = sanitize_config(sconfig, direction);
+	if (ret)
+		return NULL;
+
+	promise = kzalloc(sizeof(*promise), GFP_NOWAIT);
+	if (!promise)
+		return NULL;
+
+	promise->src = src;
+	promise->dst = dest;
+	promise->len = len;
+	promise->cfg = SUN4I_DMA_CFG_LOADING |
+		SUN4I_NDMA_CFG_BYTE_COUNT_MODE_REMAIN;
+
+	dev_dbg(chan2dev(chan),
+		"src burst %d, dst burst %d, src buswidth %d, dst buswidth %d",
+		sconfig->src_maxburst, sconfig->dst_maxburst,
+		sconfig->src_addr_width, sconfig->dst_addr_width);
+
+	/* Source burst */
+	ret = convert_burst(sconfig->src_maxburst);
+	if (IS_ERR_VALUE(ret))
+		goto fail;
+	promise->cfg |= SUN4I_DMA_CFG_SRC_BURST_LENGTH(ret);
+
+	/* Destination burst */
+	ret = convert_burst(sconfig->dst_maxburst);
+	if (IS_ERR_VALUE(ret))
+		goto fail;
+	promise->cfg |= SUN4I_DMA_CFG_DST_BURST_LENGTH(ret);
+
+	/* Source bus width */
+	ret = convert_buswidth(sconfig->src_addr_width);
+	if (IS_ERR_VALUE(ret))
+		goto fail;
+	promise->cfg |= SUN4I_DMA_CFG_SRC_DATA_WIDTH(ret);
+
+	/* Destination bus width */
+	ret = convert_buswidth(sconfig->dst_addr_width);
+	if (IS_ERR_VALUE(ret))
+		goto fail;
+	promise->cfg |= SUN4I_DMA_CFG_DST_DATA_WIDTH(ret);
+
+	return promise;
+
+fail:
+	kfree(promise);
+	return NULL;
+}
+
+/**
+ * Generate a promise, to be used in a dedicated DMA contract.
+ *
+ * A DDMA promise contains all the information required to program the
+ * Dedicated part of the DMA Engine and get data copied. A non-executed
+ * promise will live in the demands list on a contract. Once it has been
+ * completed, it will be moved to the completed demands list for later freeing.
+ * All linked promises will be freed when the corresponding contract is freed
+ */
+static struct sun4i_dma_promise *
+generate_ddma_promise(struct dma_chan *chan, dma_addr_t src, dma_addr_t dest,
+		      size_t len, struct dma_slave_config *sconfig)
+{
+	struct sun4i_dma_promise *promise;
+	int ret;
+
+	promise = kzalloc(sizeof(*promise), GFP_NOWAIT);
+	if (!promise)
+		return NULL;
+
+	promise->src = src;
+	promise->dst = dest;
+	promise->len = len;
+	promise->cfg = SUN4I_DMA_CFG_LOADING |
+		SUN4I_DDMA_CFG_BYTE_COUNT_MODE_REMAIN;
+
+	/* Source burst */
+	ret = convert_burst(sconfig->src_maxburst);
+	if (IS_ERR_VALUE(ret))
+		goto fail;
+	promise->cfg |= SUN4I_DMA_CFG_SRC_BURST_LENGTH(ret);
+
+	/* Destination burst */
+	ret = convert_burst(sconfig->dst_maxburst);
+	if (IS_ERR_VALUE(ret))
+		goto fail;
+	promise->cfg |= SUN4I_DMA_CFG_DST_BURST_LENGTH(ret);
+
+	/* Source bus width */
+	ret = convert_buswidth(sconfig->src_addr_width);
+	if (IS_ERR_VALUE(ret))
+		goto fail;
+	promise->cfg |= SUN4I_DMA_CFG_SRC_DATA_WIDTH(ret);
+
+	/* Destination bus width */
+	ret = convert_buswidth(sconfig->dst_addr_width);
+	if (IS_ERR_VALUE(ret))
+		goto fail;
+	promise->cfg |= SUN4I_DMA_CFG_DST_DATA_WIDTH(ret);
+
+	return promise;
+
+fail:
+	kfree(promise);
+	return NULL;
+}
+
+/**
+ * Generate a contract
+ *
+ * Contracts function as DMA descriptors. As our hardware does not support
+ * linked lists, we need to implement SG via software. We use a contract
+ * to hold all the pieces of the request and process them serially one
+ * after another. Each piece is represented as a promise.
+ */
+static struct sun4i_dma_contract *generate_dma_contract(void)
+{
+	struct sun4i_dma_contract *contract;
+
+	contract = kzalloc(sizeof(*contract), GFP_NOWAIT);
+	if (!contract)
+		return NULL;
+
+	INIT_LIST_HEAD(&contract->demands);
+	INIT_LIST_HEAD(&contract->completed_demands);
+
+	return contract;
+}
+
+/**
+ * Get next promise on a cyclic transfer
+ *
+ * Cyclic contracts contain a series of promises which are executed on a
+ * loop. This function returns the next promise from a cyclic contract,
+ * so it can be programmed into the hardware.
+ */
+static struct sun4i_dma_promise *
+get_next_cyclic_promise(struct sun4i_dma_contract *contract)
+{
+	struct sun4i_dma_promise *promise;
+
+	promise = list_first_entry_or_null(&contract->demands,
+					   struct sun4i_dma_promise, list);
+	if (!promise) {
+		list_splice_init(&contract->completed_demands,
+				 &contract->demands);
+		promise = list_first_entry(&contract->demands,
+					   struct sun4i_dma_promise, list);
+	}
+
+	return promise;
+}
+
+/**
+ * Free a contract and all its associated promises
+ */
+static void sun4i_dma_free_contract(struct virt_dma_desc *vd)
+{
+	struct sun4i_dma_contract *contract = to_sun4i_dma_contract(vd);
+	struct sun4i_dma_promise *promise;
+
+	/* Free all the demands and completed demands */
+	list_for_each_entry(promise, &contract->demands, list)
+		kfree(promise);
+
+	list_for_each_entry(promise, &contract->completed_demands, list)
+		kfree(promise);
+
+	kfree(contract);
+}
+
+static struct dma_async_tx_descriptor *
+sun4i_dma_prep_dma_memcpy(struct dma_chan *chan, dma_addr_t dest,
+			  dma_addr_t src, size_t len, unsigned long flags)
+{
+	struct sun4i_dma_vchan *vchan = to_sun4i_dma_vchan(chan);
+	struct dma_slave_config *sconfig = &vchan->cfg;
+	struct sun4i_dma_promise *promise;
+	struct sun4i_dma_contract *contract;
+
+	contract = generate_dma_contract();
+	if (!contract)
+		return NULL;
+
+	/*
+	 * We can only do the copy to bus aligned addresses, so
+	 * choose the best one so we get decent performance. We also
+	 * maximize the burst size for this same reason.
+	 */
+	sconfig->src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
+	sconfig->dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
+	sconfig->src_maxburst = 8;
+	sconfig->dst_maxburst = 8;
+
+	if (vchan->is_dedicated)
+		promise = generate_ddma_promise(chan, src, dest, len, sconfig);
+	else
+		promise = generate_ndma_promise(chan, src, dest, len, sconfig,
+						DMA_MEM_TO_MEM);
+
+	if (!promise) {
+		kfree(contract);
+		return NULL;
+	}
+
+	/* Configure memcpy mode */
+	if (vchan->is_dedicated) {
+		promise->cfg |= SUN4I_DMA_CFG_SRC_DRQ_TYPE(SUN4I_DDMA_DRQ_TYPE_SDRAM) |
+				SUN4I_DMA_CFG_DST_DRQ_TYPE(SUN4I_DDMA_DRQ_TYPE_SDRAM);
+	} else {
+		promise->cfg |= SUN4I_DMA_CFG_SRC_DRQ_TYPE(SUN4I_NDMA_DRQ_TYPE_SDRAM) |
+				SUN4I_DMA_CFG_DST_DRQ_TYPE(SUN4I_NDMA_DRQ_TYPE_SDRAM);
+	}
+
+	/* Fill the contract with our only promise */
+	list_add_tail(&promise->list, &contract->demands);
+
+	/* And add it to the vchan */
+	return vchan_tx_prep(&vchan->vc, &contract->vd, flags);
+}
+
+static struct dma_async_tx_descriptor *
+sun4i_dma_prep_dma_cyclic(struct dma_chan *chan, dma_addr_t buf, size_t len,
+			  size_t period_len, enum dma_transfer_direction dir,
+			  unsigned long flags)
+{
+	struct sun4i_dma_vchan *vchan = to_sun4i_dma_vchan(chan);
+	struct dma_slave_config *sconfig = &vchan->cfg;
+	struct sun4i_dma_promise *promise;
+	struct sun4i_dma_contract *contract;
+	dma_addr_t src, dest;
+	u32 endpoints;
+	int nr_periods, offset, plength, i;
+
+	if (!is_slave_direction(dir)) {
+		dev_err(chan2dev(chan), "Invalid DMA direction\n");
+		return NULL;
+	}
+
+	if (vchan->is_dedicated) {
+		/*
+		 * As we are using this just for audio data, we need to use
+		 * normal DMA. There is nothing stopping us from supporting
+		 * dedicated DMA here as well, so if a client comes up and
+		 * requires it, it will be simple to implement it.
+		 */
+		dev_err(chan2dev(chan),
+			"Cyclic transfers are only supported on Normal DMA\n");
+		return NULL;
+	}
+
+	contract = generate_dma_contract();
+	if (!contract)
+		return NULL;
+
+	contract->is_cyclic = 1;
+
+	/* Figure out the endpoints and the address we need */
+	if (dir == DMA_MEM_TO_DEV) {
+		src = buf;
+		dest = sconfig->dst_addr;
+		endpoints = SUN4I_DMA_CFG_SRC_DRQ_TYPE(SUN4I_NDMA_DRQ_TYPE_SDRAM) |
+			    SUN4I_DMA_CFG_DST_DRQ_TYPE(vchan->endpoint) |
+			    SUN4I_DMA_CFG_DST_ADDR_MODE(SUN4I_NDMA_ADDR_MODE_IO);
+	} else {
+		src = sconfig->src_addr;
+		dest = buf;
+		endpoints = SUN4I_DMA_CFG_SRC_DRQ_TYPE(vchan->endpoint) |
+			    SUN4I_DMA_CFG_SRC_ADDR_MODE(SUN4I_NDMA_ADDR_MODE_IO) |
+			    SUN4I_DMA_CFG_DST_DRQ_TYPE(SUN4I_NDMA_DRQ_TYPE_SDRAM);
+	}
+
+	/*
+	 * We will be using half done interrupts to make two periods
+	 * out of a promise, so we need to program the DMA engine less
+	 * often
+	 */
+
+	/*
+	 * The engine can interrupt on half-transfer, so we can use
+	 * this feature to program the engine half as often as if we
+	 * didn't use it (keep in mind the hardware doesn't support
+	 * linked lists).
+	 *
+	 * Say you have a set of periods (| marks the start/end, I for
+	 * interrupt, P for programming the engine to do a new
+	 * transfer), the easy but slow way would be to do
+	 *
+	 *  |---|---|---|---| (periods / promises)
+	 *  P  I,P I,P I,P  I
+	 *
+	 * Using half transfer interrupts you can do
+	 *
+	 *  |-------|-------| (promises as configured on hw)
+	 *  |---|---|---|---| (periods)
+	 *  P   I  I,P  I   I
+	 *
+	 * Which requires half the engine programming for the same
+	 * functionality.
+	 */
+	nr_periods = DIV_ROUND_UP(len / period_len, 2);
+	for (i = 0; i < nr_periods; i++) {
+		/* Calculate the offset in the buffer and the length needed */
+		offset = i * period_len * 2;
+		plength = min((len - offset), (period_len * 2));
+		if (dir == DMA_MEM_TO_DEV)
+			src = buf + offset;
+		else
+			dest = buf + offset;
+
+		/* Make the promise */
+		promise = generate_ndma_promise(chan, src, dest,
+						plength, sconfig, dir);
+		if (!promise) {
+			/* TODO: should we free everything? */
+			return NULL;
+		}
+		promise->cfg |= endpoints;
+
+		/* Then add it to the contract */
+		list_add_tail(&promise->list, &contract->demands);
+	}
+
+	/* And add it to the vchan */
+	return vchan_tx_prep(&vchan->vc, &contract->vd, flags);
+}
+
+static struct dma_async_tx_descriptor *
+sun4i_dma_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
+			unsigned int sg_len, enum dma_transfer_direction dir,
+			unsigned long flags, void *context)
+{
+	struct sun4i_dma_vchan *vchan = to_sun4i_dma_vchan(chan);
+	struct dma_slave_config *sconfig = &vchan->cfg;
+	struct sun4i_dma_promise *promise;
+	struct sun4i_dma_contract *contract;
+	u8 ram_type, io_mode, linear_mode;
+	struct scatterlist *sg;
+	dma_addr_t srcaddr, dstaddr;
+	u32 endpoints, para;
+	int i;
+
+	if (!sgl)
+		return NULL;
+
+	if (!is_slave_direction(dir)) {
+		dev_err(chan2dev(chan), "Invalid DMA direction\n");
+		return NULL;
+	}
+
+	contract = generate_dma_contract();
+	if (!contract)
+		return NULL;
+
+	if (vchan->is_dedicated) {
+		io_mode = SUN4I_DDMA_ADDR_MODE_IO;
+		linear_mode = SUN4I_DDMA_ADDR_MODE_LINEAR;
+		ram_type = SUN4I_DDMA_DRQ_TYPE_SDRAM;
+	} else {
+		io_mode = SUN4I_NDMA_ADDR_MODE_IO;
+		linear_mode = SUN4I_NDMA_ADDR_MODE_LINEAR;
+		ram_type = SUN4I_NDMA_DRQ_TYPE_SDRAM;
+	}
+
+	if (dir == DMA_MEM_TO_DEV)
+		endpoints = SUN4I_DMA_CFG_DST_DRQ_TYPE(vchan->endpoint) |
+			    SUN4I_DMA_CFG_DST_ADDR_MODE(io_mode) |
+			    SUN4I_DMA_CFG_SRC_DRQ_TYPE(ram_type) |
+			    SUN4I_DMA_CFG_SRC_ADDR_MODE(linear_mode);
+	else
+		endpoints = SUN4I_DMA_CFG_DST_DRQ_TYPE(ram_type) |
+			    SUN4I_DMA_CFG_DST_ADDR_MODE(linear_mode) |
+			    SUN4I_DMA_CFG_SRC_DRQ_TYPE(vchan->endpoint) |
+			    SUN4I_DMA_CFG_SRC_ADDR_MODE(io_mode);
+
+	for_each_sg(sgl, sg, sg_len, i) {
+		/* Figure out addresses */
+		if (dir == DMA_MEM_TO_DEV) {
+			srcaddr = sg_dma_address(sg);
+			dstaddr = sconfig->dst_addr;
+		} else {
+			srcaddr = sconfig->src_addr;
+			dstaddr = sg_dma_address(sg);
+		}
+
+		/*
+		 * These are the magic DMA engine timings that keep SPI going.
+		 * I haven't seen any interface on DMAEngine to configure
+		 * timings, and so far they seem to work for everything we
+		 * support, so I've kept them here. I don't know if other
+		 * devices need different timings because, as usual, we only
+		 * have the "para" bitfield meanings, but no comment on what
+		 * the values should be when doing a certain operation :|
+		 */
+		para = SUN4I_DDMA_MAGIC_SPI_PARAMETERS;
+
+		/* And make a suitable promise */
+		if (vchan->is_dedicated)
+			promise = generate_ddma_promise(chan, srcaddr, dstaddr,
+							sg_dma_len(sg),
+							sconfig);
+		else
+			promise = generate_ndma_promise(chan, srcaddr, dstaddr,
+							sg_dma_len(sg),
+							sconfig, dir);
+
+		if (!promise)
+			return NULL; /* TODO: should we free everything? */
+
+		promise->cfg |= endpoints;
+		promise->para = para;
+
+		/* Then add it to the contract */
+		list_add_tail(&promise->list, &contract->demands);
+	}
+
+	/*
+	 * Once we've got all the promises ready, add the contract
+	 * to the pending list on the vchan
+	 */
+	return vchan_tx_prep(&vchan->vc, &contract->vd, flags);
+}
+
+static int sun4i_dma_terminate_all(struct dma_chan *chan)
+{
+	struct sun4i_dma_dev *priv = to_sun4i_dma_dev(chan->device);
+	struct sun4i_dma_vchan *vchan = to_sun4i_dma_vchan(chan);
+	struct sun4i_dma_pchan *pchan = vchan->pchan;
+	LIST_HEAD(head);
+	unsigned long flags;
+
+	spin_lock_irqsave(&vchan->vc.lock, flags);
+	vchan_get_all_descriptors(&vchan->vc, &head);
+	spin_unlock_irqrestore(&vchan->vc.lock, flags);
+
+	/*
+	 * Clearing the configuration register will halt the pchan. Interrupts
+	 * may still trigger, so don't forget to disable them.
+	 */
+	if (pchan) {
+		if (pchan->is_dedicated)
+			writel(0, pchan->base + SUN4I_DDMA_CFG_REG);
+		else
+			writel(0, pchan->base + SUN4I_NDMA_CFG_REG);
+		set_pchan_interrupt(priv, pchan, 0, 0);
+		release_pchan(priv, pchan);
+	}
+
+	spin_lock_irqsave(&vchan->vc.lock, flags);
+	vchan_dma_desc_free_list(&vchan->vc, &head);
+	/* Clear these so the vchan is usable again */
+	vchan->processing = NULL;
+	vchan->pchan = NULL;
+	spin_unlock_irqrestore(&vchan->vc.lock, flags);
+
+	return 0;
+}
+
+static int sun4i_dma_config(struct dma_chan *chan,
+			    struct dma_slave_config *config)
+{
+	struct sun4i_dma_vchan *vchan = to_sun4i_dma_vchan(chan);
+
+	memcpy(&vchan->cfg, config, sizeof(*config));
+
+	return 0;
+}
+
+static struct dma_chan *sun4i_dma_of_xlate(struct of_phandle_args *dma_spec,
+					   struct of_dma *ofdma)
+{
+	struct sun4i_dma_dev *priv = ofdma->of_dma_data;
+	struct sun4i_dma_vchan *vchan;
+	struct dma_chan *chan;
+	u8 is_dedicated = dma_spec->args[0];
+	u8 endpoint = dma_spec->args[1];
+
+	/* Check if type is Normal or Dedicated */
+	if (is_dedicated != 0 && is_dedicated != 1)
+		return NULL;
+
+	/* Make sure the endpoint looks sane */
+	if ((is_dedicated && endpoint >= SUN4I_DDMA_DRQ_TYPE_LIMIT) ||
+	    (!is_dedicated && endpoint >= SUN4I_NDMA_DRQ_TYPE_LIMIT))
+		return NULL;
+
+	chan = dma_get_any_slave_channel(&priv->slave);
+	if (!chan)
+		return NULL;
+
+	/* Assign the endpoint to the vchan */
+	vchan = to_sun4i_dma_vchan(chan);
+	vchan->is_dedicated = is_dedicated;
+	vchan->endpoint = endpoint;
+
+	return chan;
+}
+
+static enum dma_status sun4i_dma_tx_status(struct dma_chan *chan,
+					   dma_cookie_t cookie,
+					   struct dma_tx_state *state)
+{
+	struct sun4i_dma_vchan *vchan = to_sun4i_dma_vchan(chan);
+	struct sun4i_dma_pchan *pchan = vchan->pchan;
+	struct sun4i_dma_contract *contract;
+	struct sun4i_dma_promise *promise;
+	struct virt_dma_desc *vd;
+	unsigned long flags;
+	enum dma_status ret;
+	size_t bytes = 0;
+
+	ret = dma_cookie_status(chan, cookie, state);
+	if (!state || (ret == DMA_COMPLETE))
+		return ret;
+
+	spin_lock_irqsave(&vchan->vc.lock, flags);
+	vd = vchan_find_desc(&vchan->vc, cookie);
+	if (!vd)
+		goto exit;
+	contract = to_sun4i_dma_contract(vd);
+
+	list_for_each_entry(promise, &contract->demands, list)
+		bytes += promise->len;
+
+	/*
+	 * The hardware is configured to return the remaining byte
+	 * quantity. If possible, replace the first listed element's
+	 * full size with the actual remaining amount
+	 */
+	promise = list_first_entry_or_null(&contract->demands,
+					   struct sun4i_dma_promise, list);
+	if (promise && pchan) {
+		bytes -= promise->len;
+		if (pchan->is_dedicated)
+			bytes += readl(pchan->base + SUN4I_DDMA_BYTE_COUNT_REG);
+		else
+			bytes += readl(pchan->base + SUN4I_NDMA_BYTE_COUNT_REG);
+	}
+
+exit:
+
+	dma_set_residue(state, bytes);
+	spin_unlock_irqrestore(&vchan->vc.lock, flags);
+
+	return ret;
+}
+
+static void sun4i_dma_issue_pending(struct dma_chan *chan)
+{
+	struct sun4i_dma_dev *priv = to_sun4i_dma_dev(chan->device);
+	struct sun4i_dma_vchan *vchan = to_sun4i_dma_vchan(chan);
+	unsigned long flags;
+
+	spin_lock_irqsave(&vchan->vc.lock, flags);
+
+	/*
+	 * If there are pending transactions for this vchan, push one of
+	 * them into the engine to get the ball rolling.
+	 */
+	if (vchan_issue_pending(&vchan->vc))
+		__execute_vchan_pending(priv, vchan);
+
+	spin_unlock_irqrestore(&vchan->vc.lock, flags);
+}
+
+static irqreturn_t sun4i_dma_interrupt(int irq, void *dev_id)
+{
+	struct sun4i_dma_dev *priv = dev_id;
+	struct sun4i_dma_pchan *pchans = priv->pchans, *pchan;
+	struct sun4i_dma_vchan *vchan;
+	struct sun4i_dma_contract *contract;
+	struct sun4i_dma_promise *promise;
+	unsigned long pendirq, irqs, disableirqs;
+	int bit, i, free_room, allow_mitigation = 1;
+
+	pendirq = readl_relaxed(priv->base + SUN4I_DMA_IRQ_PENDING_STATUS_REG);
+
+handle_pending:
+
+	disableirqs = 0;
+	free_room = 0;
+
+	for_each_set_bit(bit, &pendirq, 32) {
+		pchan = &pchans[bit >> 1];
+		vchan = pchan->vchan;
+		if (!vchan) /* a terminated channel may still interrupt */
+			continue;
+		contract = vchan->contract;
+
+		/*
+		 * Disable the IRQ and free the pchan if it's an end
+		 * interrupt (odd bit)
+		 */
+		if (bit & 1) {
+			spin_lock(&vchan->vc.lock);
+
+			/*
+			 * Move the promise into the completed list now that
+			 * we're done with it
+			 */
+			list_del(&vchan->processing->list);
+			list_add_tail(&vchan->processing->list,
+				      &contract->completed_demands);
+
+			/*
+			 * Cyclic DMA transfers are special:
+			 * - There's always something we can dispatch
+			 * - We need to run the callback
+			 * - Latency is very important, as this is used by audio
+			 * We therefore just cycle through the list and dispatch
+			 * whatever we have here, reusing the pchan. There's
+			 * no need to run the thread after this.
+			 *
+			 * For non-cyclic transfers we need to look around,
+			 * so we can program some more work, or notify the
+			 * client that their transfers have been completed.
+			 */
+			if (contract->is_cyclic) {
+				promise = get_next_cyclic_promise(contract);
+				vchan->processing = promise;
+				configure_pchan(pchan, promise);
+				vchan_cyclic_callback(&contract->vd);
+			} else {
+				vchan->processing = NULL;
+				vchan->pchan = NULL;
+
+				free_room = 1;
+				disableirqs |= BIT(bit);
+				release_pchan(priv, pchan);
+			}
+
+			spin_unlock(&vchan->vc.lock);
+		} else {
+			/* Half done interrupt */
+			if (contract->is_cyclic)
+				vchan_cyclic_callback(&contract->vd);
+			else
+				disableirqs |= BIT(bit);
+		}
+	}
+
+	/* Disable the IRQs for events we handled */
+	spin_lock(&priv->lock);
+	irqs = readl_relaxed(priv->base + SUN4I_DMA_IRQ_ENABLE_REG);
+	writel_relaxed(irqs & ~disableirqs,
+		       priv->base + SUN4I_DMA_IRQ_ENABLE_REG);
+	spin_unlock(&priv->lock);
+
+	/* Writing 1 to the pending field will clear the pending interrupt */
+	writel_relaxed(pendirq, priv->base + SUN4I_DMA_IRQ_PENDING_STATUS_REG);
+
+	/*
+	 * If a pchan was freed, we may be able to schedule something else,
+	 * so have a look around
+	 */
+	if (free_room) {
+		for (i = 0; i < SUN4I_DMA_NR_MAX_VCHANS; i++) {
+			vchan = &priv->vchans[i];
+			spin_lock(&vchan->vc.lock);
+			__execute_vchan_pending(priv, vchan);
+			spin_unlock(&vchan->vc.lock);
+		}
+	}
+
+	/*
+	 * Handle newer interrupts if some showed up, but only do it once
+	 * to avoid a too long a loop
+	 */
+	if (allow_mitigation) {
+		pendirq = readl_relaxed(priv->base +
+					SUN4I_DMA_IRQ_PENDING_STATUS_REG);
+		if (pendirq) {
+			allow_mitigation = 0;
+			goto handle_pending;
+		}
+	}
+
+	return IRQ_HANDLED;
+}
+
+static int sun4i_dma_probe(struct platform_device *pdev)
+{
+	struct sun4i_dma_dev *priv;
+	struct resource *res;
+	int i, j, ret;
+
+	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	priv->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(priv->base))
+		return PTR_ERR(priv->base);
+
+	priv->irq = platform_get_irq(pdev, 0);
+	if (priv->irq < 0) {
+		dev_err(&pdev->dev, "Cannot claim IRQ\n");
+		return priv->irq;
+	}
+
+	priv->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(priv->clk)) {
+		dev_err(&pdev->dev, "No clock specified\n");
+		return PTR_ERR(priv->clk);
+	}
+
+	platform_set_drvdata(pdev, priv);
+	spin_lock_init(&priv->lock);
+
+	dma_cap_zero(priv->slave.cap_mask);
+	dma_cap_set(DMA_PRIVATE, priv->slave.cap_mask);
+	dma_cap_set(DMA_MEMCPY, priv->slave.cap_mask);
+	dma_cap_set(DMA_CYCLIC, priv->slave.cap_mask);
+	dma_cap_set(DMA_SLAVE, priv->slave.cap_mask);
+
+	INIT_LIST_HEAD(&priv->slave.channels);
+	priv->slave.device_free_chan_resources	= sun4i_dma_free_chan_resources;
+	priv->slave.device_tx_status		= sun4i_dma_tx_status;
+	priv->slave.device_issue_pending	= sun4i_dma_issue_pending;
+	priv->slave.device_prep_slave_sg	= sun4i_dma_prep_slave_sg;
+	priv->slave.device_prep_dma_memcpy	= sun4i_dma_prep_dma_memcpy;
+	priv->slave.device_prep_dma_cyclic	= sun4i_dma_prep_dma_cyclic;
+	priv->slave.device_config		= sun4i_dma_config;
+	priv->slave.device_terminate_all	= sun4i_dma_terminate_all;
+	priv->slave.copy_align			= 2;
+	priv->slave.src_addr_widths		= BIT(DMA_SLAVE_BUSWIDTH_1_BYTE) |
+						  BIT(DMA_SLAVE_BUSWIDTH_2_BYTES) |
+						  BIT(DMA_SLAVE_BUSWIDTH_4_BYTES);
+	priv->slave.dst_addr_widths		= BIT(DMA_SLAVE_BUSWIDTH_1_BYTE) |
+						  BIT(DMA_SLAVE_BUSWIDTH_2_BYTES) |
+						  BIT(DMA_SLAVE_BUSWIDTH_4_BYTES);
+	priv->slave.directions			= BIT(DMA_DEV_TO_MEM) |
+						  BIT(DMA_MEM_TO_DEV);
+	priv->slave.residue_granularity		= DMA_RESIDUE_GRANULARITY_BURST;
+
+	priv->slave.dev = &pdev->dev;
+
+	priv->pchans = devm_kcalloc(&pdev->dev, SUN4I_DMA_NR_MAX_CHANNELS,
+				    sizeof(struct sun4i_dma_pchan), GFP_KERNEL);
+	priv->vchans = devm_kcalloc(&pdev->dev, SUN4I_DMA_NR_MAX_VCHANS,
+				    sizeof(struct sun4i_dma_vchan), GFP_KERNEL);
+	if (!priv->vchans || !priv->pchans)
+		return -ENOMEM;
+
+	/*
+	 * [0..SUN4I_NDMA_NR_MAX_CHANNELS) are normal pchans, and
+	 * [SUN4I_NDMA_NR_MAX_CHANNELS..SUN4I_DMA_NR_MAX_CHANNELS) are
+	 * dedicated ones
+	 */
+	for (i = 0; i < SUN4I_NDMA_NR_MAX_CHANNELS; i++)
+		priv->pchans[i].base = priv->base +
+			SUN4I_NDMA_CHANNEL_REG_BASE(i);
+
+	for (j = 0; i < SUN4I_DMA_NR_MAX_CHANNELS; i++, j++) {
+		priv->pchans[i].base = priv->base +
+			SUN4I_DDMA_CHANNEL_REG_BASE(j);
+		priv->pchans[i].is_dedicated = 1;
+	}
+
+	for (i = 0; i < SUN4I_DMA_NR_MAX_VCHANS; i++) {
+		struct sun4i_dma_vchan *vchan = &priv->vchans[i];
+
+		spin_lock_init(&vchan->vc.lock);
+		vchan->vc.desc_free = sun4i_dma_free_contract;
+		vchan_init(&vchan->vc, &priv->slave);
+	}
+
+	ret = clk_prepare_enable(priv->clk);
+	if (ret) {
+		dev_err(&pdev->dev, "Couldn't enable the clock\n");
+		return ret;
+	}
+
+	/*
+	 * Make sure the IRQs are all disabled and accounted for. The bootloader
+	 * likes to leave these dirty
+	 */
+	writel(0, priv->base + SUN4I_DMA_IRQ_ENABLE_REG);
+	writel(0xFFFFFFFF, priv->base + SUN4I_DMA_IRQ_PENDING_STATUS_REG);
+
+	ret = devm_request_irq(&pdev->dev, priv->irq, sun4i_dma_interrupt,
+			       0, dev_name(&pdev->dev), priv);
+	if (ret) {
+		dev_err(&pdev->dev, "Cannot request IRQ\n");
+		goto err_clk_disable;
+	}
+
+	ret = dma_async_device_register(&priv->slave);
+	if (ret) {
+		dev_warn(&pdev->dev, "Failed to register DMA engine device\n");
+		goto err_clk_disable;
+	}
+
+	ret = of_dma_controller_register(pdev->dev.of_node, sun4i_dma_of_xlate,
+					 priv);
+	if (ret) {
+		dev_err(&pdev->dev, "of_dma_controller_register failed\n");
+		goto err_dma_unregister;
+	}
+
+	dev_dbg(&pdev->dev, "Successfully probed SUN4I_DMA\n");
+
+	return 0;
+
+err_dma_unregister:
+	dma_async_device_unregister(&priv->slave);
+err_clk_disable:
+	clk_disable_unprepare(priv->clk);
+	return ret;
+}
+
+static int sun4i_dma_remove(struct platform_device *pdev)
+{
+	struct sun4i_dma_dev *priv = platform_get_drvdata(pdev);
+
+	/* Disable IRQ so no more work is scheduled */
+	disable_irq(priv->irq);
+
+	of_dma_controller_free(pdev->dev.of_node);
+	dma_async_device_unregister(&priv->slave);
+
+	clk_disable_unprepare(priv->clk);
+
+	return 0;
+}
+
+static const struct of_device_id sun4i_dma_match[] = {
+	{ .compatible = "allwinner,sun4i-a10-dma" },
+	{ /* sentinel */ },
+};
+
+static struct platform_driver sun4i_dma_driver = {
+	.probe	= sun4i_dma_probe,
+	.remove	= sun4i_dma_remove,
+	.driver	= {
+		.name		= "sun4i-dma",
+		.of_match_table	= sun4i_dma_match,
+	},
+};
+
+module_platform_driver(sun4i_dma_driver);
+
+MODULE_DESCRIPTION("Allwinner A10 Dedicated DMA Controller Driver");
+MODULE_AUTHOR("Emilio López <emilio@elopez.com.ar>");
+MODULE_LICENSE("GPL");