Adding upstream version 6.6.15.upstream/6.6.15

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

1 files changed, 2271 insertions, 0 deletions

diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c
new file mode 100644
index 000000000..b2876f674
--- /dev/null
+++ b/drivers/dma/at_hdmac.c
@@ -0,0 +1,2271 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Driver for the Atmel AHB DMA Controller (aka HDMA or DMAC on AT91 systems)
+ *
+ * Copyright (C) 2008 Atmel Corporation
+ * Copyright (C) 2022 Microchip Technology, Inc. and its subsidiaries
+ *
+ * This supports the Atmel AHB DMA Controller found in several Atmel SoCs.
+ * The only Atmel DMA Controller that is not covered by this driver is the one
+ * found on AT91SAM9263.
+ */
+
+#include <dt-bindings/dma/at91.h>
+#include <linux/bitfield.h>
+#include <linux/clk.h>
+#include <linux/dmaengine.h>
+#include <linux/dmapool.h>
+#include <linux/dma-mapping.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/overflow.h>
+#include <linux/of_platform.h>
+#include <linux/of_dma.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+#include "dmaengine.h"
+#include "virt-dma.h"
+
+/*
+ * Glossary
+ * --------
+ *
+ * at_hdmac		: Name of the ATmel AHB DMA Controller
+ * at_dma_ / atdma	: ATmel DMA controller entity related
+ * atc_	/ atchan	: ATmel DMA Channel entity related
+ */
+
+#define	AT_DMA_MAX_NR_CHANNELS	8
+
+/* Global Configuration Register */
+#define AT_DMA_GCFG		0x00
+#define AT_DMA_IF_BIGEND(i)	BIT((i))	/* AHB-Lite Interface i in Big-endian mode */
+#define AT_DMA_ARB_CFG		BIT(4)		/* Arbiter mode. */
+
+/* Controller Enable Register */
+#define AT_DMA_EN		0x04
+#define AT_DMA_ENABLE		BIT(0)
+
+/* Software Single Request Register */
+#define AT_DMA_SREQ		0x08
+#define AT_DMA_SSREQ(x)		BIT((x) << 1)		/* Request a source single transfer on channel x */
+#define AT_DMA_DSREQ(x)		BIT(1 + ((x) << 1))	/* Request a destination single transfer on channel x */
+
+/* Software Chunk Transfer Request Register */
+#define AT_DMA_CREQ		0x0c
+#define AT_DMA_SCREQ(x)		BIT((x) << 1)		/* Request a source chunk transfer on channel x */
+#define AT_DMA_DCREQ(x)		BIT(1 + ((x) << 1))	/* Request a destination chunk transfer on channel x */
+
+/* Software Last Transfer Flag Register */
+#define AT_DMA_LAST		0x10
+#define AT_DMA_SLAST(x)		BIT((x) << 1)		/* This src rq is last tx of buffer on channel x */
+#define AT_DMA_DLAST(x)		BIT(1 + ((x) << 1))	/* This dst rq is last tx of buffer on channel x */
+
+/* Request Synchronization Register */
+#define AT_DMA_SYNC		0x14
+#define AT_DMA_SYR(h)		BIT((h))		/* Synchronize handshake line h */
+
+/* Error, Chained Buffer transfer completed and Buffer transfer completed Interrupt registers */
+#define AT_DMA_EBCIER		0x18			/* Enable register */
+#define AT_DMA_EBCIDR		0x1c			/* Disable register */
+#define AT_DMA_EBCIMR		0x20			/* Mask Register */
+#define AT_DMA_EBCISR		0x24			/* Status Register */
+#define AT_DMA_CBTC_OFFSET	8
+#define AT_DMA_ERR_OFFSET	16
+#define AT_DMA_BTC(x)		BIT((x))
+#define AT_DMA_CBTC(x)		BIT(AT_DMA_CBTC_OFFSET + (x))
+#define AT_DMA_ERR(x)		BIT(AT_DMA_ERR_OFFSET + (x))
+
+/* Channel Handler Enable Register */
+#define AT_DMA_CHER		0x28
+#define AT_DMA_ENA(x)		BIT((x))
+#define AT_DMA_SUSP(x)		BIT(8 + (x))
+#define AT_DMA_KEEP(x)		BIT(24 + (x))
+
+/* Channel Handler Disable Register */
+#define AT_DMA_CHDR		0x2c
+#define AT_DMA_DIS(x)		BIT(x)
+#define AT_DMA_RES(x)		BIT(8 + (x))
+
+/* Channel Handler Status Register */
+#define AT_DMA_CHSR		0x30
+#define AT_DMA_EMPT(x)		BIT(16 + (x))
+#define AT_DMA_STAL(x)		BIT(24 + (x))
+
+/* Channel registers base address */
+#define AT_DMA_CH_REGS_BASE	0x3c
+#define ch_regs(x)		(AT_DMA_CH_REGS_BASE + (x) * 0x28) /* Channel x base addr */
+
+/* Hardware register offset for each channel */
+#define ATC_SADDR_OFFSET	0x00	/* Source Address Register */
+#define ATC_DADDR_OFFSET	0x04	/* Destination Address Register */
+#define ATC_DSCR_OFFSET		0x08	/* Descriptor Address Register */
+#define ATC_CTRLA_OFFSET	0x0c	/* Control A Register */
+#define ATC_CTRLB_OFFSET	0x10	/* Control B Register */
+#define ATC_CFG_OFFSET		0x14	/* Configuration Register */
+#define ATC_SPIP_OFFSET		0x18	/* Src PIP Configuration Register */
+#define ATC_DPIP_OFFSET		0x1c	/* Dst PIP Configuration Register */
+
+
+/* Bitfield definitions */
+
+/* Bitfields in DSCR */
+#define ATC_DSCR_IF		GENMASK(1, 0)	/* Dsc feched via AHB-Lite Interface */
+
+/* Bitfields in CTRLA */
+#define ATC_BTSIZE_MAX		GENMASK(15, 0)	/* Maximum Buffer Transfer Size */
+#define ATC_BTSIZE		GENMASK(15, 0)	/* Buffer Transfer Size */
+#define ATC_SCSIZE		GENMASK(18, 16)	/* Source Chunk Transfer Size */
+#define ATC_DCSIZE		GENMASK(22, 20)	/* Destination Chunk Transfer Size */
+#define ATC_SRC_WIDTH		GENMASK(25, 24)	/* Source Single Transfer Size */
+#define ATC_DST_WIDTH		GENMASK(29, 28)	/* Destination Single Transfer Size */
+#define ATC_DONE		BIT(31)	/* Tx Done (only written back in descriptor) */
+
+/* Bitfields in CTRLB */
+#define ATC_SIF			GENMASK(1, 0)	/* Src tx done via AHB-Lite Interface i */
+#define ATC_DIF			GENMASK(5, 4)	/* Dst tx done via AHB-Lite Interface i */
+#define AT_DMA_MEM_IF		0x0		/* interface 0 as memory interface */
+#define AT_DMA_PER_IF		0x1		/* interface 1 as peripheral interface */
+#define ATC_SRC_PIP		BIT(8)		/* Source Picture-in-Picture enabled */
+#define ATC_DST_PIP		BIT(12)		/* Destination Picture-in-Picture enabled */
+#define ATC_SRC_DSCR_DIS	BIT(16)		/* Src Descriptor fetch disable */
+#define ATC_DST_DSCR_DIS	BIT(20)		/* Dst Descriptor fetch disable */
+#define ATC_FC			GENMASK(23, 21)	/* Choose Flow Controller */
+#define ATC_FC_MEM2MEM		0x0		/* Mem-to-Mem (DMA) */
+#define ATC_FC_MEM2PER		0x1		/* Mem-to-Periph (DMA) */
+#define ATC_FC_PER2MEM		0x2		/* Periph-to-Mem (DMA) */
+#define ATC_FC_PER2PER		0x3		/* Periph-to-Periph (DMA) */
+#define ATC_FC_PER2MEM_PER	0x4		/* Periph-to-Mem (Peripheral) */
+#define ATC_FC_MEM2PER_PER	0x5		/* Mem-to-Periph (Peripheral) */
+#define ATC_FC_PER2PER_SRCPER	0x6		/* Periph-to-Periph (Src Peripheral) */
+#define ATC_FC_PER2PER_DSTPER	0x7		/* Periph-to-Periph (Dst Peripheral) */
+#define ATC_SRC_ADDR_MODE	GENMASK(25, 24)
+#define ATC_SRC_ADDR_MODE_INCR	0x0		/* Incrementing Mode */
+#define ATC_SRC_ADDR_MODE_DECR	0x1		/* Decrementing Mode */
+#define ATC_SRC_ADDR_MODE_FIXED	0x2		/* Fixed Mode */
+#define ATC_DST_ADDR_MODE	GENMASK(29, 28)
+#define ATC_DST_ADDR_MODE_INCR	0x0		/* Incrementing Mode */
+#define ATC_DST_ADDR_MODE_DECR	0x1		/* Decrementing Mode */
+#define ATC_DST_ADDR_MODE_FIXED	0x2		/* Fixed Mode */
+#define ATC_IEN			BIT(30)		/* BTC interrupt enable (active low) */
+#define ATC_AUTO		BIT(31)		/* Auto multiple buffer tx enable */
+
+/* Bitfields in CFG */
+#define ATC_SRC_PER		GENMASK(3, 0)	/* Channel src rq associated with periph handshaking ifc h */
+#define ATC_DST_PER		GENMASK(7, 4)	/* Channel dst rq associated with periph handshaking ifc h */
+#define ATC_SRC_REP		BIT(8)		/* Source Replay Mod */
+#define ATC_SRC_H2SEL		BIT(9)		/* Source Handshaking Mod */
+#define ATC_SRC_PER_MSB		GENMASK(11, 10)	/* Channel src rq (most significant bits) */
+#define ATC_DST_REP		BIT(12)		/* Destination Replay Mod */
+#define ATC_DST_H2SEL		BIT(13)		/* Destination Handshaking Mod */
+#define ATC_DST_PER_MSB		GENMASK(15, 14)	/* Channel dst rq (most significant bits) */
+#define ATC_SOD			BIT(16)		/* Stop On Done */
+#define ATC_LOCK_IF		BIT(20)		/* Interface Lock */
+#define ATC_LOCK_B		BIT(21)		/* AHB Bus Lock */
+#define ATC_LOCK_IF_L		BIT(22)		/* Master Interface Arbiter Lock */
+#define ATC_AHB_PROT		GENMASK(26, 24)	/* AHB Protection */
+#define ATC_FIFOCFG		GENMASK(29, 28)	/* FIFO Request Configuration */
+#define ATC_FIFOCFG_LARGESTBURST	0x0
+#define ATC_FIFOCFG_HALFFIFO		0x1
+#define ATC_FIFOCFG_ENOUGHSPACE		0x2
+
+/* Bitfields in SPIP */
+#define ATC_SPIP_HOLE		GENMASK(15, 0)
+#define ATC_SPIP_BOUNDARY	GENMASK(25, 16)
+
+/* Bitfields in DPIP */
+#define ATC_DPIP_HOLE		GENMASK(15, 0)
+#define ATC_DPIP_BOUNDARY	GENMASK(25, 16)
+
+#define ATC_PER_MSB		GENMASK(5, 4)	/* Extract MSBs of a handshaking identifier */
+#define ATC_SRC_PER_ID(id)					       \
+	({ typeof(id) _id = (id);				       \
+	   FIELD_PREP(ATC_SRC_PER_MSB, FIELD_GET(ATC_PER_MSB, _id)) |  \
+	   FIELD_PREP(ATC_SRC_PER, _id); })
+#define ATC_DST_PER_ID(id)					       \
+	({ typeof(id) _id = (id);				       \
+	   FIELD_PREP(ATC_DST_PER_MSB, FIELD_GET(ATC_PER_MSB, _id)) |  \
+	   FIELD_PREP(ATC_DST_PER, _id); })
+
+
+
+/*--  descriptors  -----------------------------------------------------*/
+
+/* LLI == Linked List Item; aka DMA buffer descriptor */
+struct at_lli {
+	/* values that are not changed by hardware */
+	u32 saddr;
+	u32 daddr;
+	/* value that may get written back: */
+	u32 ctrla;
+	/* more values that are not changed by hardware */
+	u32 ctrlb;
+	u32 dscr;	/* chain to next lli */
+};
+
+/**
+ * struct atdma_sg - atdma scatter gather entry
+ * @len: length of the current Linked List Item.
+ * @lli: linked list item that is passed to the DMA controller
+ * @lli_phys: physical address of the LLI.
+ */
+struct atdma_sg {
+	unsigned int len;
+	struct at_lli *lli;
+	dma_addr_t lli_phys;
+};
+
+/**
+ * struct at_desc - software descriptor
+ * @vd: pointer to the virtual dma descriptor.
+ * @atchan: pointer to the atmel dma channel.
+ * @total_len: total transaction byte count
+ * @sg_len: number of sg entries.
+ * @sg: array of sgs.
+ */
+struct at_desc {
+	struct				virt_dma_desc vd;
+	struct				at_dma_chan *atchan;
+	size_t				total_len;
+	unsigned int			sglen;
+	/* Interleaved data */
+	size_t				boundary;
+	size_t				dst_hole;
+	size_t				src_hole;
+
+	/* Memset temporary buffer */
+	bool				memset_buffer;
+	dma_addr_t			memset_paddr;
+	int				*memset_vaddr;
+	struct atdma_sg			sg[];
+};
+
+/*--  Channels  --------------------------------------------------------*/
+
+/**
+ * atc_status - information bits stored in channel status flag
+ *
+ * Manipulated with atomic operations.
+ */
+enum atc_status {
+	ATC_IS_PAUSED = 1,
+	ATC_IS_CYCLIC = 24,
+};
+
+/**
+ * struct at_dma_chan - internal representation of an Atmel HDMAC channel
+ * @vc: virtual dma channel entry.
+ * @atdma: pointer to the driver data.
+ * @ch_regs: memory mapped register base
+ * @mask: channel index in a mask
+ * @per_if: peripheral interface
+ * @mem_if: memory interface
+ * @status: transmit status information from irq/prep* functions
+ *                to tasklet (use atomic operations)
+ * @save_cfg: configuration register that is saved on suspend/resume cycle
+ * @save_dscr: for cyclic operations, preserve next descriptor address in
+ *             the cyclic list on suspend/resume cycle
+ * @dma_sconfig: configuration for slave transfers, passed via
+ * .device_config
+ * @desc: pointer to the atmel dma descriptor.
+ */
+struct at_dma_chan {
+	struct virt_dma_chan	vc;
+	struct at_dma		*atdma;
+	void __iomem		*ch_regs;
+	u8			mask;
+	u8			per_if;
+	u8			mem_if;
+	unsigned long		status;
+	u32			save_cfg;
+	u32			save_dscr;
+	struct dma_slave_config	dma_sconfig;
+	bool			cyclic;
+	struct at_desc		*desc;
+};
+
+#define	channel_readl(atchan, name) \
+	__raw_readl((atchan)->ch_regs + ATC_##name##_OFFSET)
+
+#define	channel_writel(atchan, name, val) \
+	__raw_writel((val), (atchan)->ch_regs + ATC_##name##_OFFSET)
+
+/*
+ * Fix sconfig's burst size according to at_hdmac. We need to convert them as:
+ * 1 -> 0, 4 -> 1, 8 -> 2, 16 -> 3, 32 -> 4, 64 -> 5, 128 -> 6, 256 -> 7.
+ *
+ * This can be done by finding most significant bit set.
+ */
+static inline void convert_burst(u32 *maxburst)
+{
+	if (*maxburst > 1)
+		*maxburst = fls(*maxburst) - 2;
+	else
+		*maxburst = 0;
+}
+
+/*
+ * Fix sconfig's bus width according to at_hdmac.
+ * 1 byte -> 0, 2 bytes -> 1, 4 bytes -> 2.
+ */
+static inline u8 convert_buswidth(enum dma_slave_buswidth addr_width)
+{
+	switch (addr_width) {
+	case DMA_SLAVE_BUSWIDTH_2_BYTES:
+		return 1;
+	case DMA_SLAVE_BUSWIDTH_4_BYTES:
+		return 2;
+	default:
+		/* For 1 byte width or fallback */
+		return 0;
+	}
+}
+
+/*--  Controller  ------------------------------------------------------*/
+
+/**
+ * struct at_dma - internal representation of an Atmel HDMA Controller
+ * @dma_device: dmaengine dma_device object members
+ * @atdma_devtype: identifier of DMA controller compatibility
+ * @ch_regs: memory mapped register base
+ * @clk: dma controller clock
+ * @save_imr: interrupt mask register that is saved on suspend/resume cycle
+ * @all_chan_mask: all channels availlable in a mask
+ * @lli_pool: hw lli table
+ * @chan: channels table to store at_dma_chan structures
+ */
+struct at_dma {
+	struct dma_device	dma_device;
+	void __iomem		*regs;
+	struct clk		*clk;
+	u32			save_imr;
+
+	u8			all_chan_mask;
+
+	struct dma_pool		*lli_pool;
+	struct dma_pool		*memset_pool;
+	/* AT THE END channels table */
+	struct at_dma_chan	chan[];
+};
+
+#define	dma_readl(atdma, name) \
+	__raw_readl((atdma)->regs + AT_DMA_##name)
+#define	dma_writel(atdma, name, val) \
+	__raw_writel((val), (atdma)->regs + AT_DMA_##name)
+
+static inline struct at_desc *to_atdma_desc(struct dma_async_tx_descriptor *t)
+{
+	return container_of(t, struct at_desc, vd.tx);
+}
+
+static inline struct at_dma_chan *to_at_dma_chan(struct dma_chan *chan)
+{
+	return container_of(chan, struct at_dma_chan, vc.chan);
+}
+
+static inline struct at_dma *to_at_dma(struct dma_device *ddev)
+{
+	return container_of(ddev, struct at_dma, dma_device);
+}
+
+
+/*--  Helper functions  ------------------------------------------------*/
+
+static struct device *chan2dev(struct dma_chan *chan)
+{
+	return &chan->dev->device;
+}
+
+#if defined(VERBOSE_DEBUG)
+static void vdbg_dump_regs(struct at_dma_chan *atchan)
+{
+	struct at_dma	*atdma = to_at_dma(atchan->vc.chan.device);
+
+	dev_err(chan2dev(&atchan->vc.chan),
+		"  channel %d : imr = 0x%x, chsr = 0x%x\n",
+		atchan->vc.chan.chan_id,
+		dma_readl(atdma, EBCIMR),
+		dma_readl(atdma, CHSR));
+
+	dev_err(chan2dev(&atchan->vc.chan),
+		"  channel: s0x%x d0x%x ctrl0x%x:0x%x cfg0x%x l0x%x\n",
+		channel_readl(atchan, SADDR),
+		channel_readl(atchan, DADDR),
+		channel_readl(atchan, CTRLA),
+		channel_readl(atchan, CTRLB),
+		channel_readl(atchan, CFG),
+		channel_readl(atchan, DSCR));
+}
+#else
+static void vdbg_dump_regs(struct at_dma_chan *atchan) {}
+#endif
+
+static void atc_dump_lli(struct at_dma_chan *atchan, struct at_lli *lli)
+{
+	dev_crit(chan2dev(&atchan->vc.chan),
+		 "desc: s%pad d%pad ctrl0x%x:0x%x l%pad\n",
+		 &lli->saddr, &lli->daddr,
+		 lli->ctrla, lli->ctrlb, &lli->dscr);
+}
+
+
+static void atc_setup_irq(struct at_dma *atdma, int chan_id, int on)
+{
+	u32 ebci;
+
+	/* enable interrupts on buffer transfer completion & error */
+	ebci =    AT_DMA_BTC(chan_id)
+		| AT_DMA_ERR(chan_id);
+	if (on)
+		dma_writel(atdma, EBCIER, ebci);
+	else
+		dma_writel(atdma, EBCIDR, ebci);
+}
+
+static void atc_enable_chan_irq(struct at_dma *atdma, int chan_id)
+{
+	atc_setup_irq(atdma, chan_id, 1);
+}
+
+static void atc_disable_chan_irq(struct at_dma *atdma, int chan_id)
+{
+	atc_setup_irq(atdma, chan_id, 0);
+}
+
+
+/**
+ * atc_chan_is_enabled - test if given channel is enabled
+ * @atchan: channel we want to test status
+ */
+static inline int atc_chan_is_enabled(struct at_dma_chan *atchan)
+{
+	struct at_dma *atdma = to_at_dma(atchan->vc.chan.device);
+
+	return !!(dma_readl(atdma, CHSR) & atchan->mask);
+}
+
+/**
+ * atc_chan_is_paused - test channel pause/resume status
+ * @atchan: channel we want to test status
+ */
+static inline int atc_chan_is_paused(struct at_dma_chan *atchan)
+{
+	return test_bit(ATC_IS_PAUSED, &atchan->status);
+}
+
+/**
+ * atc_chan_is_cyclic - test if given channel has cyclic property set
+ * @atchan: channel we want to test status
+ */
+static inline int atc_chan_is_cyclic(struct at_dma_chan *atchan)
+{
+	return test_bit(ATC_IS_CYCLIC, &atchan->status);
+}
+
+/**
+ * set_lli_eol - set end-of-link to descriptor so it will end transfer
+ * @desc: descriptor, signle or at the end of a chain, to end chain on
+ * @i: index of the atmel scatter gather entry that is at the end of the chain.
+ */
+static void set_lli_eol(struct at_desc *desc, unsigned int i)
+{
+	u32 ctrlb = desc->sg[i].lli->ctrlb;
+
+	ctrlb &= ~ATC_IEN;
+	ctrlb |= ATC_SRC_DSCR_DIS | ATC_DST_DSCR_DIS;
+
+	desc->sg[i].lli->ctrlb = ctrlb;
+	desc->sg[i].lli->dscr = 0;
+}
+
+#define	ATC_DEFAULT_CFG		FIELD_PREP(ATC_FIFOCFG, ATC_FIFOCFG_HALFFIFO)
+#define	ATC_DEFAULT_CTRLB	(FIELD_PREP(ATC_SIF, AT_DMA_MEM_IF) | \
+				 FIELD_PREP(ATC_DIF, AT_DMA_MEM_IF))
+#define ATC_DMA_BUSWIDTHS\
+	(BIT(DMA_SLAVE_BUSWIDTH_UNDEFINED) |\
+	BIT(DMA_SLAVE_BUSWIDTH_1_BYTE) |\
+	BIT(DMA_SLAVE_BUSWIDTH_2_BYTES) |\
+	BIT(DMA_SLAVE_BUSWIDTH_4_BYTES))
+
+#define ATC_MAX_DSCR_TRIALS	10
+
+/*
+ * Initial number of descriptors to allocate for each channel. This could
+ * be increased during dma usage.
+ */
+static unsigned int init_nr_desc_per_channel = 64;
+module_param(init_nr_desc_per_channel, uint, 0644);
+MODULE_PARM_DESC(init_nr_desc_per_channel,
+		 "initial descriptors per channel (default: 64)");
+
+/**
+ * struct at_dma_platform_data - Controller configuration parameters
+ * @nr_channels: Number of channels supported by hardware (max 8)
+ * @cap_mask: dma_capability flags supported by the platform
+ */
+struct at_dma_platform_data {
+	unsigned int	nr_channels;
+	dma_cap_mask_t  cap_mask;
+};
+
+/**
+ * struct at_dma_slave - Controller-specific information about a slave
+ * @dma_dev: required DMA master device
+ * @cfg: Platform-specific initializer for the CFG register
+ */
+struct at_dma_slave {
+	struct device		*dma_dev;
+	u32			cfg;
+};
+
+static inline unsigned int atc_get_xfer_width(dma_addr_t src, dma_addr_t dst,
+						size_t len)
+{
+	unsigned int width;
+
+	if (!((src | dst  | len) & 3))
+		width = 2;
+	else if (!((src | dst | len) & 1))
+		width = 1;
+	else
+		width = 0;
+
+	return width;
+}
+
+static void atdma_lli_chain(struct at_desc *desc, unsigned int i)
+{
+	struct atdma_sg *atdma_sg = &desc->sg[i];
+
+	if (i)
+		desc->sg[i - 1].lli->dscr = atdma_sg->lli_phys;
+}
+
+/**
+ * atc_dostart - starts the DMA engine for real
+ * @atchan: the channel we want to start
+ */
+static void atc_dostart(struct at_dma_chan *atchan)
+{
+	struct virt_dma_desc *vd = vchan_next_desc(&atchan->vc);
+	struct at_desc *desc;
+
+	if (!vd) {
+		atchan->desc = NULL;
+		return;
+	}
+
+	vdbg_dump_regs(atchan);
+
+	list_del(&vd->node);
+	atchan->desc = desc = to_atdma_desc(&vd->tx);
+
+	channel_writel(atchan, SADDR, 0);
+	channel_writel(atchan, DADDR, 0);
+	channel_writel(atchan, CTRLA, 0);
+	channel_writel(atchan, CTRLB, 0);
+	channel_writel(atchan, DSCR, desc->sg[0].lli_phys);
+	channel_writel(atchan, SPIP,
+		       FIELD_PREP(ATC_SPIP_HOLE, desc->src_hole) |
+		       FIELD_PREP(ATC_SPIP_BOUNDARY, desc->boundary));
+	channel_writel(atchan, DPIP,
+		       FIELD_PREP(ATC_DPIP_HOLE, desc->dst_hole) |
+		       FIELD_PREP(ATC_DPIP_BOUNDARY, desc->boundary));
+
+	/* Don't allow CPU to reorder channel enable. */
+	wmb();
+	dma_writel(atchan->atdma, CHER, atchan->mask);
+
+	vdbg_dump_regs(atchan);
+}
+
+static void atdma_desc_free(struct virt_dma_desc *vd)
+{
+	struct at_dma *atdma = to_at_dma(vd->tx.chan->device);
+	struct at_desc *desc = to_atdma_desc(&vd->tx);
+	unsigned int i;
+
+	for (i = 0; i < desc->sglen; i++) {
+		if (desc->sg[i].lli)
+			dma_pool_free(atdma->lli_pool, desc->sg[i].lli,
+				      desc->sg[i].lli_phys);
+	}
+
+	/* If the transfer was a memset, free our temporary buffer */
+	if (desc->memset_buffer) {
+		dma_pool_free(atdma->memset_pool, desc->memset_vaddr,
+			      desc->memset_paddr);
+		desc->memset_buffer = false;
+	}
+
+	kfree(desc);
+}
+
+/**
+ * atc_calc_bytes_left - calculates the number of bytes left according to the
+ * value read from CTRLA.
+ *
+ * @current_len: the number of bytes left before reading CTRLA
+ * @ctrla: the value of CTRLA
+ */
+static inline u32 atc_calc_bytes_left(u32 current_len, u32 ctrla)
+{
+	u32 btsize = FIELD_GET(ATC_BTSIZE, ctrla);
+	u32 src_width = FIELD_GET(ATC_SRC_WIDTH, ctrla);
+
+	/*
+	 * According to the datasheet, when reading the Control A Register
+	 * (ctrla), the Buffer Transfer Size (btsize) bitfield refers to the
+	 * number of transfers completed on the Source Interface.
+	 * So btsize is always a number of source width transfers.
+	 */
+	return current_len - (btsize << src_width);
+}
+
+/**
+ * atc_get_llis_residue - Get residue for a hardware linked list transfer
+ *
+ * Calculate the residue by removing the length of the Linked List Item (LLI)
+ * already transferred from the total length. To get the current LLI we can use
+ * the value of the channel's DSCR register and compare it against the DSCR
+ * value of each LLI.
+ *
+ * The CTRLA register provides us with the amount of data already read from the
+ * source for the LLI. So we can compute a more accurate residue by also
+ * removing the number of bytes corresponding to this amount of data.
+ *
+ * However, the DSCR and CTRLA registers cannot be read both atomically. Hence a
+ * race condition may occur: the first read register may refer to one LLI
+ * whereas the second read may refer to a later LLI in the list because of the
+ * DMA transfer progression inbetween the two reads.
+ *
+ * One solution could have been to pause the DMA transfer, read the DSCR and
+ * CTRLA then resume the DMA transfer. Nonetheless, this approach presents some
+ * drawbacks:
+ * - If the DMA transfer is paused, RX overruns or TX underruns are more likey
+ *   to occur depending on the system latency. Taking the USART driver as an
+ *   example, it uses a cyclic DMA transfer to read data from the Receive
+ *   Holding Register (RHR) to avoid RX overruns since the RHR is not protected
+ *   by any FIFO on most Atmel SoCs. So pausing the DMA transfer to compute the
+ *   residue would break the USART driver design.
+ * - The atc_pause() function masks interrupts but we'd rather avoid to do so
+ * for system latency purpose.
+ *
+ * Then we'd rather use another solution: the DSCR is read a first time, the
+ * CTRLA is read in turn, next the DSCR is read a second time. If the two
+ * consecutive read values of the DSCR are the same then we assume both refers
+ * to the very same LLI as well as the CTRLA value read inbetween does. For
+ * cyclic tranfers, the assumption is that a full loop is "not so fast". If the
+ * two DSCR values are different, we read again the CTRLA then the DSCR till two
+ * consecutive read values from DSCR are equal or till the maximum trials is
+ * reach. This algorithm is very unlikely not to find a stable value for DSCR.
+ * @atchan: pointer to an atmel hdmac channel.
+ * @desc: pointer to the descriptor for which the residue is calculated.
+ * @residue: residue to be set to dma_tx_state.
+ * Returns 0 on success, -errno otherwise.
+ */
+static int atc_get_llis_residue(struct at_dma_chan *atchan,
+				struct at_desc *desc, u32 *residue)
+{
+	u32 len, ctrla, dscr;
+	unsigned int i;
+
+	len = desc->total_len;
+	dscr = channel_readl(atchan, DSCR);
+	rmb(); /* ensure DSCR is read before CTRLA */
+	ctrla = channel_readl(atchan, CTRLA);
+	for (i = 0; i < ATC_MAX_DSCR_TRIALS; ++i) {
+		u32 new_dscr;
+
+		rmb(); /* ensure DSCR is read after CTRLA */
+		new_dscr = channel_readl(atchan, DSCR);
+
+		/*
+		 * If the DSCR register value has not changed inside the DMA
+		 * controller since the previous read, we assume that both the
+		 * dscr and ctrla values refers to the very same descriptor.
+		 */
+		if (likely(new_dscr == dscr))
+			break;
+
+		/*
+		 * DSCR has changed inside the DMA controller, so the previouly
+		 * read value of CTRLA may refer to an already processed
+		 * descriptor hence could be outdated. We need to update ctrla
+		 * to match the current descriptor.
+		 */
+		dscr = new_dscr;
+		rmb(); /* ensure DSCR is read before CTRLA */
+		ctrla = channel_readl(atchan, CTRLA);
+	}
+	if (unlikely(i == ATC_MAX_DSCR_TRIALS))
+		return -ETIMEDOUT;
+
+	/* For the first descriptor we can be more accurate. */
+	if (desc->sg[0].lli->dscr == dscr) {
+		*residue = atc_calc_bytes_left(len, ctrla);
+		return 0;
+	}
+	len -= desc->sg[0].len;
+
+	for (i = 1; i < desc->sglen; i++) {
+		if (desc->sg[i].lli && desc->sg[i].lli->dscr == dscr)
+			break;
+		len -= desc->sg[i].len;
+	}
+
+	/*
+	 * For the current LLI in the chain we can calculate the remaining bytes
+	 * using the channel's CTRLA register.
+	 */
+	*residue = atc_calc_bytes_left(len, ctrla);
+	return 0;
+
+}
+
+/**
+ * atc_get_residue - get the number of bytes residue for a cookie.
+ * The residue is passed by address and updated on success.
+ * @chan: DMA channel
+ * @cookie: transaction identifier to check status of
+ * @residue: residue to be updated.
+ * Return 0 on success, -errono otherwise.
+ */
+static int atc_get_residue(struct dma_chan *chan, dma_cookie_t cookie,
+			   u32 *residue)
+{
+	struct at_dma_chan *atchan = to_at_dma_chan(chan);
+	struct virt_dma_desc *vd;
+	struct at_desc *desc = NULL;
+	u32 len, ctrla;
+
+	vd = vchan_find_desc(&atchan->vc, cookie);
+	if (vd)
+		desc = to_atdma_desc(&vd->tx);
+	else if (atchan->desc && atchan->desc->vd.tx.cookie == cookie)
+		desc = atchan->desc;
+
+	if (!desc)
+		return -EINVAL;
+
+	if (desc->sg[0].lli->dscr)
+		/* hardware linked list transfer */
+		return atc_get_llis_residue(atchan, desc, residue);
+
+	/* single transfer */
+	len = desc->total_len;
+	ctrla = channel_readl(atchan, CTRLA);
+	*residue = atc_calc_bytes_left(len, ctrla);
+	return 0;
+}
+
+/**
+ * atc_handle_error - handle errors reported by DMA controller
+ * @atchan: channel where error occurs.
+ * @i: channel index
+ */
+static void atc_handle_error(struct at_dma_chan *atchan, unsigned int i)
+{
+	struct at_desc *desc = atchan->desc;
+
+	/* Disable channel on AHB error */
+	dma_writel(atchan->atdma, CHDR, AT_DMA_RES(i) | atchan->mask);
+
+	/*
+	 * KERN_CRITICAL may seem harsh, but since this only happens
+	 * when someone submits a bad physical address in a
+	 * descriptor, we should consider ourselves lucky that the
+	 * controller flagged an error instead of scribbling over
+	 * random memory locations.
+	 */
+	dev_crit(chan2dev(&atchan->vc.chan), "Bad descriptor submitted for DMA!\n");
+	dev_crit(chan2dev(&atchan->vc.chan), "cookie: %d\n",
+		 desc->vd.tx.cookie);
+	for (i = 0; i < desc->sglen; i++)
+		atc_dump_lli(atchan, desc->sg[i].lli);
+}
+
+static void atdma_handle_chan_done(struct at_dma_chan *atchan, u32 pending,
+				   unsigned int i)
+{
+	struct at_desc *desc;
+
+	spin_lock(&atchan->vc.lock);
+	desc = atchan->desc;
+
+	if (desc) {
+		if (pending & AT_DMA_ERR(i)) {
+			atc_handle_error(atchan, i);
+			/* Pretend the descriptor completed successfully */
+		}
+
+		if (atc_chan_is_cyclic(atchan)) {
+			vchan_cyclic_callback(&desc->vd);
+		} else {
+			vchan_cookie_complete(&desc->vd);
+			atchan->desc = NULL;
+			if (!(atc_chan_is_enabled(atchan)))
+				atc_dostart(atchan);
+		}
+	}
+	spin_unlock(&atchan->vc.lock);
+}
+
+static irqreturn_t at_dma_interrupt(int irq, void *dev_id)
+{
+	struct at_dma		*atdma = dev_id;
+	struct at_dma_chan	*atchan;
+	int			i;
+	u32			status, pending, imr;
+	int			ret = IRQ_NONE;
+
+	do {
+		imr = dma_readl(atdma, EBCIMR);
+		status = dma_readl(atdma, EBCISR);
+		pending = status & imr;
+
+		if (!pending)
+			break;
+
+		dev_vdbg(atdma->dma_device.dev,
+			"interrupt: status = 0x%08x, 0x%08x, 0x%08x\n",
+			 status, imr, pending);
+
+		for (i = 0; i < atdma->dma_device.chancnt; i++) {
+			atchan = &atdma->chan[i];
+			if (!(pending & (AT_DMA_BTC(i) | AT_DMA_ERR(i))))
+				continue;
+			atdma_handle_chan_done(atchan, pending, i);
+			ret = IRQ_HANDLED;
+		}
+
+	} while (pending);
+
+	return ret;
+}
+
+/*--  DMA Engine API  --------------------------------------------------*/
+/**
+ * atc_prep_dma_interleaved - prepare memory to memory interleaved operation
+ * @chan: the channel to prepare operation on
+ * @xt: Interleaved transfer template
+ * @flags: tx descriptor status flags
+ */
+static struct dma_async_tx_descriptor *
+atc_prep_dma_interleaved(struct dma_chan *chan,
+			 struct dma_interleaved_template *xt,
+			 unsigned long flags)
+{
+	struct at_dma		*atdma = to_at_dma(chan->device);
+	struct at_dma_chan	*atchan = to_at_dma_chan(chan);
+	struct data_chunk	*first;
+	struct atdma_sg		*atdma_sg;
+	struct at_desc		*desc;
+	struct at_lli		*lli;
+	size_t			xfer_count;
+	unsigned int		dwidth;
+	u32			ctrla;
+	u32			ctrlb;
+	size_t			len = 0;
+	int			i;
+
+	if (unlikely(!xt || xt->numf != 1 || !xt->frame_size))
+		return NULL;
+
+	first = xt->sgl;
+
+	dev_info(chan2dev(chan),
+		 "%s: src=%pad, dest=%pad, numf=%d, frame_size=%d, flags=0x%lx\n",
+		__func__, &xt->src_start, &xt->dst_start, xt->numf,
+		xt->frame_size, flags);
+
+	/*
+	 * The controller can only "skip" X bytes every Y bytes, so we
+	 * need to make sure we are given a template that fit that
+	 * description, ie a template with chunks that always have the
+	 * same size, with the same ICGs.
+	 */
+	for (i = 0; i < xt->frame_size; i++) {
+		struct data_chunk *chunk = xt->sgl + i;
+
+		if ((chunk->size != xt->sgl->size) ||
+		    (dmaengine_get_dst_icg(xt, chunk) != dmaengine_get_dst_icg(xt, first)) ||
+		    (dmaengine_get_src_icg(xt, chunk) != dmaengine_get_src_icg(xt, first))) {
+			dev_err(chan2dev(chan),
+				"%s: the controller can transfer only identical chunks\n",
+				__func__);
+			return NULL;
+		}
+
+		len += chunk->size;
+	}
+
+	dwidth = atc_get_xfer_width(xt->src_start, xt->dst_start, len);
+
+	xfer_count = len >> dwidth;
+	if (xfer_count > ATC_BTSIZE_MAX) {
+		dev_err(chan2dev(chan), "%s: buffer is too big\n", __func__);
+		return NULL;
+	}
+
+	ctrla = FIELD_PREP(ATC_SRC_WIDTH, dwidth) |
+		FIELD_PREP(ATC_DST_WIDTH, dwidth);
+
+	ctrlb = ATC_DEFAULT_CTRLB | ATC_IEN |
+		FIELD_PREP(ATC_SRC_ADDR_MODE, ATC_SRC_ADDR_MODE_INCR) |
+		FIELD_PREP(ATC_DST_ADDR_MODE, ATC_DST_ADDR_MODE_INCR) |
+		ATC_SRC_PIP | ATC_DST_PIP |
+		FIELD_PREP(ATC_FC, ATC_FC_MEM2MEM);
+
+	desc = kzalloc(struct_size(desc, sg, 1), GFP_ATOMIC);
+	if (!desc)
+		return NULL;
+	desc->sglen = 1;
+
+	atdma_sg = desc->sg;
+	atdma_sg->lli = dma_pool_alloc(atdma->lli_pool, GFP_NOWAIT,
+				       &atdma_sg->lli_phys);
+	if (!atdma_sg->lli) {
+		kfree(desc);
+		return NULL;
+	}
+	lli = atdma_sg->lli;
+
+	lli->saddr = xt->src_start;
+	lli->daddr = xt->dst_start;
+	lli->ctrla = ctrla | xfer_count;
+	lli->ctrlb = ctrlb;
+
+	desc->boundary = first->size >> dwidth;
+	desc->dst_hole = (dmaengine_get_dst_icg(xt, first) >> dwidth) + 1;
+	desc->src_hole = (dmaengine_get_src_icg(xt, first) >> dwidth) + 1;
+
+	atdma_sg->len = len;
+	desc->total_len = len;
+
+	set_lli_eol(desc, 0);
+	return vchan_tx_prep(&atchan->vc, &desc->vd, flags);
+}
+
+/**
+ * atc_prep_dma_memcpy - prepare a memcpy operation
+ * @chan: the channel to prepare operation on
+ * @dest: operation virtual destination address
+ * @src: operation virtual source address
+ * @len: operation length
+ * @flags: tx descriptor status flags
+ */
+static struct dma_async_tx_descriptor *
+atc_prep_dma_memcpy(struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
+		size_t len, unsigned long flags)
+{
+	struct at_dma		*atdma = to_at_dma(chan->device);
+	struct at_dma_chan	*atchan = to_at_dma_chan(chan);
+	struct at_desc		*desc = NULL;
+	size_t			xfer_count;
+	size_t			offset;
+	size_t			sg_len;
+	unsigned int		src_width;
+	unsigned int		dst_width;
+	unsigned int		i;
+	u32			ctrla;
+	u32			ctrlb;
+
+	dev_dbg(chan2dev(chan), "prep_dma_memcpy: d%pad s%pad l0x%zx f0x%lx\n",
+		&dest, &src, len, flags);
+
+	if (unlikely(!len)) {
+		dev_err(chan2dev(chan), "prep_dma_memcpy: length is zero!\n");
+		return NULL;
+	}
+
+	sg_len = DIV_ROUND_UP(len, ATC_BTSIZE_MAX);
+	desc = kzalloc(struct_size(desc, sg, sg_len), GFP_ATOMIC);
+	if (!desc)
+		return NULL;
+	desc->sglen = sg_len;
+
+	ctrlb = ATC_DEFAULT_CTRLB | ATC_IEN |
+		FIELD_PREP(ATC_SRC_ADDR_MODE, ATC_SRC_ADDR_MODE_INCR) |
+		FIELD_PREP(ATC_DST_ADDR_MODE, ATC_DST_ADDR_MODE_INCR) |
+		FIELD_PREP(ATC_FC, ATC_FC_MEM2MEM);
+
+	/*
+	 * We can be a lot more clever here, but this should take care
+	 * of the most common optimization.
+	 */
+	src_width = dst_width = atc_get_xfer_width(src, dest, len);
+
+	ctrla = FIELD_PREP(ATC_SRC_WIDTH, src_width) |
+		FIELD_PREP(ATC_DST_WIDTH, dst_width);
+
+	for (offset = 0, i = 0; offset < len;
+	     offset += xfer_count << src_width, i++) {
+		struct atdma_sg *atdma_sg = &desc->sg[i];
+		struct at_lli *lli;
+
+		atdma_sg->lli = dma_pool_alloc(atdma->lli_pool, GFP_NOWAIT,
+					       &atdma_sg->lli_phys);
+		if (!atdma_sg->lli)
+			goto err_desc_get;
+		lli = atdma_sg->lli;
+
+		xfer_count = min_t(size_t, (len - offset) >> src_width,
+				   ATC_BTSIZE_MAX);
+
+		lli->saddr = src + offset;
+		lli->daddr = dest + offset;
+		lli->ctrla = ctrla | xfer_count;
+		lli->ctrlb = ctrlb;
+
+		desc->sg[i].len = xfer_count << src_width;
+
+		atdma_lli_chain(desc, i);
+	}
+
+	desc->total_len = len;
+
+	/* set end-of-link to the last link descriptor of list*/
+	set_lli_eol(desc, i - 1);
+
+	return vchan_tx_prep(&atchan->vc, &desc->vd, flags);
+
+err_desc_get:
+	atdma_desc_free(&desc->vd);
+	return NULL;
+}
+
+static int atdma_create_memset_lli(struct dma_chan *chan,
+				   struct atdma_sg *atdma_sg,
+				   dma_addr_t psrc, dma_addr_t pdst, size_t len)
+{
+	struct at_dma *atdma = to_at_dma(chan->device);
+	struct at_lli *lli;
+	size_t xfer_count;
+	u32 ctrla = FIELD_PREP(ATC_SRC_WIDTH, 2) | FIELD_PREP(ATC_DST_WIDTH, 2);
+	u32 ctrlb = ATC_DEFAULT_CTRLB | ATC_IEN |
+		    FIELD_PREP(ATC_SRC_ADDR_MODE, ATC_SRC_ADDR_MODE_FIXED) |
+		    FIELD_PREP(ATC_DST_ADDR_MODE, ATC_DST_ADDR_MODE_INCR) |
+		    FIELD_PREP(ATC_FC, ATC_FC_MEM2MEM);
+
+	xfer_count = len >> 2;
+	if (xfer_count > ATC_BTSIZE_MAX) {
+		dev_err(chan2dev(chan), "%s: buffer is too big\n", __func__);
+		return -EINVAL;
+	}
+
+	atdma_sg->lli = dma_pool_alloc(atdma->lli_pool, GFP_NOWAIT,
+				       &atdma_sg->lli_phys);
+	if (!atdma_sg->lli)
+		return -ENOMEM;
+	lli = atdma_sg->lli;
+
+	lli->saddr = psrc;
+	lli->daddr = pdst;
+	lli->ctrla = ctrla | xfer_count;
+	lli->ctrlb = ctrlb;
+
+	atdma_sg->len = len;
+
+	return 0;
+}
+
+/**
+ * atc_prep_dma_memset - prepare a memcpy operation
+ * @chan: the channel to prepare operation on
+ * @dest: operation virtual destination address
+ * @value: value to set memory buffer to
+ * @len: operation length
+ * @flags: tx descriptor status flags
+ */
+static struct dma_async_tx_descriptor *
+atc_prep_dma_memset(struct dma_chan *chan, dma_addr_t dest, int value,
+		    size_t len, unsigned long flags)
+{
+	struct at_dma_chan	*atchan = to_at_dma_chan(chan);
+	struct at_dma		*atdma = to_at_dma(chan->device);
+	struct at_desc		*desc;
+	void __iomem		*vaddr;
+	dma_addr_t		paddr;
+	char			fill_pattern;
+	int			ret;
+
+	dev_vdbg(chan2dev(chan), "%s: d%pad v0x%x l0x%zx f0x%lx\n", __func__,
+		&dest, value, len, flags);
+
+	if (unlikely(!len)) {
+		dev_dbg(chan2dev(chan), "%s: length is zero!\n", __func__);
+		return NULL;
+	}
+
+	if (!is_dma_fill_aligned(chan->device, dest, 0, len)) {
+		dev_dbg(chan2dev(chan), "%s: buffer is not aligned\n",
+			__func__);
+		return NULL;
+	}
+
+	vaddr = dma_pool_alloc(atdma->memset_pool, GFP_NOWAIT, &paddr);
+	if (!vaddr) {
+		dev_err(chan2dev(chan), "%s: couldn't allocate buffer\n",
+			__func__);
+		return NULL;
+	}
+
+	/* Only the first byte of value is to be used according to dmaengine */
+	fill_pattern = (char)value;
+
+	*(u32*)vaddr = (fill_pattern << 24) |
+		       (fill_pattern << 16) |
+		       (fill_pattern << 8) |
+		       fill_pattern;
+
+	desc = kzalloc(struct_size(desc, sg, 1), GFP_ATOMIC);
+	if (!desc)
+		goto err_free_buffer;
+	desc->sglen = 1;
+
+	ret = atdma_create_memset_lli(chan, desc->sg, paddr, dest, len);
+	if (ret)
+		goto err_free_desc;
+
+	desc->memset_paddr = paddr;
+	desc->memset_vaddr = vaddr;
+	desc->memset_buffer = true;
+
+	desc->total_len = len;
+
+	/* set end-of-link on the descriptor */
+	set_lli_eol(desc, 0);
+
+	return vchan_tx_prep(&atchan->vc, &desc->vd, flags);
+
+err_free_desc:
+	kfree(desc);
+err_free_buffer:
+	dma_pool_free(atdma->memset_pool, vaddr, paddr);
+	return NULL;
+}
+
+static struct dma_async_tx_descriptor *
+atc_prep_dma_memset_sg(struct dma_chan *chan,
+		       struct scatterlist *sgl,
+		       unsigned int sg_len, int value,
+		       unsigned long flags)
+{
+	struct at_dma_chan	*atchan = to_at_dma_chan(chan);
+	struct at_dma		*atdma = to_at_dma(chan->device);
+	struct at_desc		*desc;
+	struct scatterlist	*sg;
+	void __iomem		*vaddr;
+	dma_addr_t		paddr;
+	size_t			total_len = 0;
+	int			i;
+	int			ret;
+
+	dev_vdbg(chan2dev(chan), "%s: v0x%x l0x%zx f0x%lx\n", __func__,
+		 value, sg_len, flags);
+
+	if (unlikely(!sgl || !sg_len)) {
+		dev_dbg(chan2dev(chan), "%s: scatterlist is empty!\n",
+			__func__);
+		return NULL;
+	}
+
+	vaddr = dma_pool_alloc(atdma->memset_pool, GFP_NOWAIT, &paddr);
+	if (!vaddr) {
+		dev_err(chan2dev(chan), "%s: couldn't allocate buffer\n",
+			__func__);
+		return NULL;
+	}
+	*(u32*)vaddr = value;
+
+	desc = kzalloc(struct_size(desc, sg, sg_len), GFP_ATOMIC);
+	if (!desc)
+		goto err_free_dma_buf;
+	desc->sglen = sg_len;
+
+	for_each_sg(sgl, sg, sg_len, i) {
+		dma_addr_t dest = sg_dma_address(sg);
+		size_t len = sg_dma_len(sg);
+
+		dev_vdbg(chan2dev(chan), "%s: d%pad, l0x%zx\n",
+			 __func__, &dest, len);
+
+		if (!is_dma_fill_aligned(chan->device, dest, 0, len)) {
+			dev_err(chan2dev(chan), "%s: buffer is not aligned\n",
+				__func__);
+			goto err_free_desc;
+		}
+
+		ret = atdma_create_memset_lli(chan, &desc->sg[i], paddr, dest,
+					      len);
+		if (ret)
+			goto err_free_desc;
+
+		atdma_lli_chain(desc, i);
+		total_len += len;
+	}
+
+	desc->memset_paddr = paddr;
+	desc->memset_vaddr = vaddr;
+	desc->memset_buffer = true;
+
+	desc->total_len = total_len;
+
+	/* set end-of-link on the descriptor */
+	set_lli_eol(desc, i - 1);
+
+	return vchan_tx_prep(&atchan->vc, &desc->vd, flags);
+
+err_free_desc:
+	atdma_desc_free(&desc->vd);
+err_free_dma_buf:
+	dma_pool_free(atdma->memset_pool, vaddr, paddr);
+	return NULL;
+}
+
+/**
+ * atc_prep_slave_sg - prepare descriptors for a DMA_SLAVE transaction
+ * @chan: DMA channel
+ * @sgl: scatterlist to transfer to/from
+ * @sg_len: number of entries in @scatterlist
+ * @direction: DMA direction
+ * @flags: tx descriptor status flags
+ * @context: transaction context (ignored)
+ */
+static struct dma_async_tx_descriptor *
+atc_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
+		unsigned int sg_len, enum dma_transfer_direction direction,
+		unsigned long flags, void *context)
+{
+	struct at_dma		*atdma = to_at_dma(chan->device);
+	struct at_dma_chan	*atchan = to_at_dma_chan(chan);
+	struct at_dma_slave	*atslave = chan->private;
+	struct dma_slave_config	*sconfig = &atchan->dma_sconfig;
+	struct at_desc		*desc;
+	u32			ctrla;
+	u32			ctrlb;
+	dma_addr_t		reg;
+	unsigned int		reg_width;
+	unsigned int		mem_width;
+	unsigned int		i;
+	struct scatterlist	*sg;
+	size_t			total_len = 0;
+
+	dev_vdbg(chan2dev(chan), "prep_slave_sg (%d): %s f0x%lx\n",
+			sg_len,
+			direction == DMA_MEM_TO_DEV ? "TO DEVICE" : "FROM DEVICE",
+			flags);
+
+	if (unlikely(!atslave || !sg_len)) {
+		dev_dbg(chan2dev(chan), "prep_slave_sg: sg length is zero!\n");
+		return NULL;
+	}
+
+	desc = kzalloc(struct_size(desc, sg, sg_len), GFP_ATOMIC);
+	if (!desc)
+		return NULL;
+	desc->sglen = sg_len;
+
+	ctrla = FIELD_PREP(ATC_SCSIZE, sconfig->src_maxburst) |
+		FIELD_PREP(ATC_DCSIZE, sconfig->dst_maxburst);
+	ctrlb = ATC_IEN;
+
+	switch (direction) {
+	case DMA_MEM_TO_DEV:
+		reg_width = convert_buswidth(sconfig->dst_addr_width);
+		ctrla |= FIELD_PREP(ATC_DST_WIDTH, reg_width);
+		ctrlb |= FIELD_PREP(ATC_DST_ADDR_MODE,
+				    ATC_DST_ADDR_MODE_FIXED) |
+			 FIELD_PREP(ATC_SRC_ADDR_MODE, ATC_SRC_ADDR_MODE_INCR) |
+			 FIELD_PREP(ATC_FC, ATC_FC_MEM2PER) |
+			 FIELD_PREP(ATC_SIF, atchan->mem_if) |
+			 FIELD_PREP(ATC_DIF, atchan->per_if);
+		reg = sconfig->dst_addr;
+		for_each_sg(sgl, sg, sg_len, i) {
+			struct atdma_sg *atdma_sg = &desc->sg[i];
+			struct at_lli *lli;
+			u32		len;
+			u32		mem;
+
+			atdma_sg->lli = dma_pool_alloc(atdma->lli_pool,
+						       GFP_NOWAIT,
+						       &atdma_sg->lli_phys);
+			if (!atdma_sg->lli)
+				goto err_desc_get;
+			lli = atdma_sg->lli;
+
+			mem = sg_dma_address(sg);
+			len = sg_dma_len(sg);
+			if (unlikely(!len)) {
+				dev_dbg(chan2dev(chan),
+					"prep_slave_sg: sg(%d) data length is zero\n", i);
+				goto err;
+			}
+			mem_width = 2;
+			if (unlikely(mem & 3 || len & 3))
+				mem_width = 0;
+
+			lli->saddr = mem;
+			lli->daddr = reg;
+			lli->ctrla = ctrla |
+				     FIELD_PREP(ATC_SRC_WIDTH, mem_width) |
+				     len >> mem_width;
+			lli->ctrlb = ctrlb;
+
+			atdma_sg->len = len;
+			total_len += len;
+
+			desc->sg[i].len = len;
+			atdma_lli_chain(desc, i);
+		}
+		break;
+	case DMA_DEV_TO_MEM:
+		reg_width = convert_buswidth(sconfig->src_addr_width);
+		ctrla |= FIELD_PREP(ATC_SRC_WIDTH, reg_width);
+		ctrlb |= FIELD_PREP(ATC_DST_ADDR_MODE, ATC_DST_ADDR_MODE_INCR) |
+			 FIELD_PREP(ATC_SRC_ADDR_MODE,
+				    ATC_SRC_ADDR_MODE_FIXED) |
+			 FIELD_PREP(ATC_FC, ATC_FC_PER2MEM) |
+			 FIELD_PREP(ATC_SIF, atchan->per_if) |
+			 FIELD_PREP(ATC_DIF, atchan->mem_if);
+
+		reg = sconfig->src_addr;
+		for_each_sg(sgl, sg, sg_len, i) {
+			struct atdma_sg *atdma_sg = &desc->sg[i];
+			struct at_lli *lli;
+			u32		len;
+			u32		mem;
+
+			atdma_sg->lli = dma_pool_alloc(atdma->lli_pool,
+						       GFP_NOWAIT,
+						       &atdma_sg->lli_phys);
+			if (!atdma_sg->lli)
+				goto err_desc_get;
+			lli = atdma_sg->lli;
+
+			mem = sg_dma_address(sg);
+			len = sg_dma_len(sg);
+			if (unlikely(!len)) {
+				dev_dbg(chan2dev(chan),
+					"prep_slave_sg: sg(%d) data length is zero\n", i);
+				goto err;
+			}
+			mem_width = 2;
+			if (unlikely(mem & 3 || len & 3))
+				mem_width = 0;
+
+			lli->saddr = reg;
+			lli->daddr = mem;
+			lli->ctrla = ctrla |
+				     FIELD_PREP(ATC_DST_WIDTH, mem_width) |
+				     len >> reg_width;
+			lli->ctrlb = ctrlb;
+
+			desc->sg[i].len = len;
+			total_len += len;
+
+			atdma_lli_chain(desc, i);
+		}
+		break;
+	default:
+		return NULL;
+	}
+
+	/* set end-of-link to the last link descriptor of list*/
+	set_lli_eol(desc, i - 1);
+
+	desc->total_len = total_len;
+
+	return vchan_tx_prep(&atchan->vc, &desc->vd, flags);
+
+err_desc_get:
+	dev_err(chan2dev(chan), "not enough descriptors available\n");
+err:
+	atdma_desc_free(&desc->vd);
+	return NULL;
+}
+
+/*
+ * atc_dma_cyclic_check_values
+ * Check for too big/unaligned periods and unaligned DMA buffer
+ */
+static int
+atc_dma_cyclic_check_values(unsigned int reg_width, dma_addr_t buf_addr,
+		size_t period_len)
+{
+	if (period_len > (ATC_BTSIZE_MAX << reg_width))
+		goto err_out;
+	if (unlikely(period_len & ((1 << reg_width) - 1)))
+		goto err_out;
+	if (unlikely(buf_addr & ((1 << reg_width) - 1)))
+		goto err_out;
+
+	return 0;
+
+err_out:
+	return -EINVAL;
+}
+
+/*
+ * atc_dma_cyclic_fill_desc - Fill one period descriptor
+ */
+static int
+atc_dma_cyclic_fill_desc(struct dma_chan *chan, struct at_desc *desc,
+		unsigned int i, dma_addr_t buf_addr,
+		unsigned int reg_width, size_t period_len,
+		enum dma_transfer_direction direction)
+{
+	struct at_dma		*atdma = to_at_dma(chan->device);
+	struct at_dma_chan	*atchan = to_at_dma_chan(chan);
+	struct dma_slave_config	*sconfig = &atchan->dma_sconfig;
+	struct atdma_sg		*atdma_sg = &desc->sg[i];
+	struct at_lli		*lli;
+
+	atdma_sg->lli = dma_pool_alloc(atdma->lli_pool, GFP_ATOMIC,
+				       &atdma_sg->lli_phys);
+	if (!atdma_sg->lli)
+		return -ENOMEM;
+	lli = atdma_sg->lli;
+
+	switch (direction) {
+	case DMA_MEM_TO_DEV:
+		lli->saddr = buf_addr + (period_len * i);
+		lli->daddr = sconfig->dst_addr;
+		lli->ctrlb = FIELD_PREP(ATC_DST_ADDR_MODE,
+					ATC_DST_ADDR_MODE_FIXED) |
+			     FIELD_PREP(ATC_SRC_ADDR_MODE,
+					ATC_SRC_ADDR_MODE_INCR) |
+			     FIELD_PREP(ATC_FC, ATC_FC_MEM2PER) |
+			     FIELD_PREP(ATC_SIF, atchan->mem_if) |
+			     FIELD_PREP(ATC_DIF, atchan->per_if);
+
+		break;
+
+	case DMA_DEV_TO_MEM:
+		lli->saddr = sconfig->src_addr;
+		lli->daddr = buf_addr + (period_len * i);
+		lli->ctrlb = FIELD_PREP(ATC_DST_ADDR_MODE,
+					ATC_DST_ADDR_MODE_INCR) |
+			     FIELD_PREP(ATC_SRC_ADDR_MODE,
+					ATC_SRC_ADDR_MODE_FIXED) |
+			     FIELD_PREP(ATC_FC, ATC_FC_PER2MEM) |
+			     FIELD_PREP(ATC_SIF, atchan->per_if) |
+			     FIELD_PREP(ATC_DIF, atchan->mem_if);
+		break;
+
+	default:
+		return -EINVAL;
+	}
+
+	lli->ctrla = FIELD_PREP(ATC_SCSIZE, sconfig->src_maxburst) |
+		     FIELD_PREP(ATC_DCSIZE, sconfig->dst_maxburst) |
+		     FIELD_PREP(ATC_DST_WIDTH, reg_width) |
+		     FIELD_PREP(ATC_SRC_WIDTH, reg_width) |
+		     period_len >> reg_width;
+	desc->sg[i].len = period_len;
+
+	return 0;
+}
+
+/**
+ * atc_prep_dma_cyclic - prepare the cyclic DMA transfer
+ * @chan: the DMA channel to prepare
+ * @buf_addr: physical DMA address where the buffer starts
+ * @buf_len: total number of bytes for the entire buffer
+ * @period_len: number of bytes for each period
+ * @direction: transfer direction, to or from device
+ * @flags: tx descriptor status flags
+ */
+static struct dma_async_tx_descriptor *
+atc_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 at_dma_chan	*atchan = to_at_dma_chan(chan);
+	struct at_dma_slave	*atslave = chan->private;
+	struct dma_slave_config	*sconfig = &atchan->dma_sconfig;
+	struct at_desc		*desc;
+	unsigned long		was_cyclic;
+	unsigned int		reg_width;
+	unsigned int		periods = buf_len / period_len;
+	unsigned int		i;
+
+	dev_vdbg(chan2dev(chan), "prep_dma_cyclic: %s buf@%pad - %d (%d/%d)\n",
+			direction == DMA_MEM_TO_DEV ? "TO DEVICE" : "FROM DEVICE",
+			&buf_addr,
+			periods, buf_len, period_len);
+
+	if (unlikely(!atslave || !buf_len || !period_len)) {
+		dev_dbg(chan2dev(chan), "prep_dma_cyclic: length is zero!\n");
+		return NULL;
+	}
+
+	was_cyclic = test_and_set_bit(ATC_IS_CYCLIC, &atchan->status);
+	if (was_cyclic) {
+		dev_dbg(chan2dev(chan), "prep_dma_cyclic: channel in use!\n");
+		return NULL;
+	}
+
+	if (unlikely(!is_slave_direction(direction)))
+		goto err_out;
+
+	if (direction == DMA_MEM_TO_DEV)
+		reg_width = convert_buswidth(sconfig->dst_addr_width);
+	else
+		reg_width = convert_buswidth(sconfig->src_addr_width);
+
+	/* Check for too big/unaligned periods and unaligned DMA buffer */
+	if (atc_dma_cyclic_check_values(reg_width, buf_addr, period_len))
+		goto err_out;
+
+	desc = kzalloc(struct_size(desc, sg, periods), GFP_ATOMIC);
+	if (!desc)
+		goto err_out;
+	desc->sglen = periods;
+
+	/* build cyclic linked list */
+	for (i = 0; i < periods; i++) {
+		if (atc_dma_cyclic_fill_desc(chan, desc, i, buf_addr,
+					     reg_width, period_len, direction))
+			goto err_fill_desc;
+		atdma_lli_chain(desc, i);
+	}
+	desc->total_len = buf_len;
+	/* lets make a cyclic list */
+	desc->sg[i - 1].lli->dscr = desc->sg[0].lli_phys;
+
+	return vchan_tx_prep(&atchan->vc, &desc->vd, flags);
+
+err_fill_desc:
+	atdma_desc_free(&desc->vd);
+err_out:
+	clear_bit(ATC_IS_CYCLIC, &atchan->status);
+	return NULL;
+}
+
+static int atc_config(struct dma_chan *chan,
+		      struct dma_slave_config *sconfig)
+{
+	struct at_dma_chan	*atchan = to_at_dma_chan(chan);
+
+	dev_vdbg(chan2dev(chan), "%s\n", __func__);
+
+	/* Check if it is chan is configured for slave transfers */
+	if (!chan->private)
+		return -EINVAL;
+
+	memcpy(&atchan->dma_sconfig, sconfig, sizeof(*sconfig));
+
+	convert_burst(&atchan->dma_sconfig.src_maxburst);
+	convert_burst(&atchan->dma_sconfig.dst_maxburst);
+
+	return 0;
+}
+
+static int atc_pause(struct dma_chan *chan)
+{
+	struct at_dma_chan	*atchan = to_at_dma_chan(chan);
+	struct at_dma		*atdma = to_at_dma(chan->device);
+	int			chan_id = atchan->vc.chan.chan_id;
+	unsigned long		flags;
+
+	dev_vdbg(chan2dev(chan), "%s\n", __func__);
+
+	spin_lock_irqsave(&atchan->vc.lock, flags);
+
+	dma_writel(atdma, CHER, AT_DMA_SUSP(chan_id));
+	set_bit(ATC_IS_PAUSED, &atchan->status);
+
+	spin_unlock_irqrestore(&atchan->vc.lock, flags);
+
+	return 0;
+}
+
+static int atc_resume(struct dma_chan *chan)
+{
+	struct at_dma_chan	*atchan = to_at_dma_chan(chan);
+	struct at_dma		*atdma = to_at_dma(chan->device);
+	int			chan_id = atchan->vc.chan.chan_id;
+	unsigned long		flags;
+
+	dev_vdbg(chan2dev(chan), "%s\n", __func__);
+
+	if (!atc_chan_is_paused(atchan))
+		return 0;
+
+	spin_lock_irqsave(&atchan->vc.lock, flags);
+
+	dma_writel(atdma, CHDR, AT_DMA_RES(chan_id));
+	clear_bit(ATC_IS_PAUSED, &atchan->status);
+
+	spin_unlock_irqrestore(&atchan->vc.lock, flags);
+
+	return 0;
+}
+
+static int atc_terminate_all(struct dma_chan *chan)
+{
+	struct at_dma_chan	*atchan = to_at_dma_chan(chan);
+	struct at_dma		*atdma = to_at_dma(chan->device);
+	int			chan_id = atchan->vc.chan.chan_id;
+	unsigned long		flags;
+
+	LIST_HEAD(list);
+
+	dev_vdbg(chan2dev(chan), "%s\n", __func__);
+
+	/*
+	 * This is only called when something went wrong elsewhere, so
+	 * we don't really care about the data. Just disable the
+	 * channel. We still have to poll the channel enable bit due
+	 * to AHB/HSB limitations.
+	 */
+	spin_lock_irqsave(&atchan->vc.lock, flags);
+
+	/* disabling channel: must also remove suspend state */
+	dma_writel(atdma, CHDR, AT_DMA_RES(chan_id) | atchan->mask);
+
+	/* confirm that this channel is disabled */
+	while (dma_readl(atdma, CHSR) & atchan->mask)
+		cpu_relax();
+
+	if (atchan->desc) {
+		vchan_terminate_vdesc(&atchan->desc->vd);
+		atchan->desc = NULL;
+	}
+
+	vchan_get_all_descriptors(&atchan->vc, &list);
+
+	clear_bit(ATC_IS_PAUSED, &atchan->status);
+	/* if channel dedicated to cyclic operations, free it */
+	clear_bit(ATC_IS_CYCLIC, &atchan->status);
+
+	spin_unlock_irqrestore(&atchan->vc.lock, flags);
+
+	vchan_dma_desc_free_list(&atchan->vc, &list);
+
+	return 0;
+}
+
+/**
+ * atc_tx_status - poll for transaction completion
+ * @chan: DMA channel
+ * @cookie: transaction identifier to check status of
+ * @txstate: if not %NULL updated with transaction state
+ *
+ * If @txstate is passed in, upon return it reflect the driver
+ * internal state and can be used with dma_async_is_complete() to check
+ * the status of multiple cookies without re-checking hardware state.
+ */
+static enum dma_status
+atc_tx_status(struct dma_chan *chan,
+		dma_cookie_t cookie,
+		struct dma_tx_state *txstate)
+{
+	struct at_dma_chan	*atchan = to_at_dma_chan(chan);
+	unsigned long		flags;
+	enum dma_status		dma_status;
+	u32 residue;
+	int ret;
+
+	dma_status = dma_cookie_status(chan, cookie, txstate);
+	if (dma_status == DMA_COMPLETE || !txstate)
+		return dma_status;
+
+	spin_lock_irqsave(&atchan->vc.lock, flags);
+	/*  Get number of bytes left in the active transactions */
+	ret = atc_get_residue(chan, cookie, &residue);
+	spin_unlock_irqrestore(&atchan->vc.lock, flags);
+
+	if (unlikely(ret < 0)) {
+		dev_vdbg(chan2dev(chan), "get residual bytes error\n");
+		return DMA_ERROR;
+	} else {
+		dma_set_residue(txstate, residue);
+	}
+
+	dev_vdbg(chan2dev(chan), "tx_status %d: cookie = %d residue = %u\n",
+		 dma_status, cookie, residue);
+
+	return dma_status;
+}
+
+static void atc_issue_pending(struct dma_chan *chan)
+{
+	struct at_dma_chan *atchan = to_at_dma_chan(chan);
+	unsigned long flags;
+
+	spin_lock_irqsave(&atchan->vc.lock, flags);
+	if (vchan_issue_pending(&atchan->vc) && !atchan->desc) {
+		if (!(atc_chan_is_enabled(atchan)))
+			atc_dostart(atchan);
+	}
+	spin_unlock_irqrestore(&atchan->vc.lock, flags);
+}
+
+/**
+ * atc_alloc_chan_resources - allocate resources for DMA channel
+ * @chan: allocate descriptor resources for this channel
+ *
+ * return - the number of allocated descriptors
+ */
+static int atc_alloc_chan_resources(struct dma_chan *chan)
+{
+	struct at_dma_chan	*atchan = to_at_dma_chan(chan);
+	struct at_dma		*atdma = to_at_dma(chan->device);
+	struct at_dma_slave	*atslave;
+	u32			cfg;
+
+	dev_vdbg(chan2dev(chan), "alloc_chan_resources\n");
+
+	/* ASSERT:  channel is idle */
+	if (atc_chan_is_enabled(atchan)) {
+		dev_dbg(chan2dev(chan), "DMA channel not idle ?\n");
+		return -EIO;
+	}
+
+	cfg = ATC_DEFAULT_CFG;
+
+	atslave = chan->private;
+	if (atslave) {
+		/*
+		 * We need controller-specific data to set up slave
+		 * transfers.
+		 */
+		BUG_ON(!atslave->dma_dev || atslave->dma_dev != atdma->dma_device.dev);
+
+		/* if cfg configuration specified take it instead of default */
+		if (atslave->cfg)
+			cfg = atslave->cfg;
+	}
+
+	/* channel parameters */
+	channel_writel(atchan, CFG, cfg);
+
+	return 0;
+}
+
+/**
+ * atc_free_chan_resources - free all channel resources
+ * @chan: DMA channel
+ */
+static void atc_free_chan_resources(struct dma_chan *chan)
+{
+	struct at_dma_chan	*atchan = to_at_dma_chan(chan);
+
+	BUG_ON(atc_chan_is_enabled(atchan));
+
+	vchan_free_chan_resources(to_virt_chan(chan));
+	atchan->status = 0;
+
+	/*
+	 * Free atslave allocated in at_dma_xlate()
+	 */
+	kfree(chan->private);
+	chan->private = NULL;
+
+	dev_vdbg(chan2dev(chan), "free_chan_resources: done\n");
+}
+
+#ifdef CONFIG_OF
+static bool at_dma_filter(struct dma_chan *chan, void *slave)
+{
+	struct at_dma_slave *atslave = slave;
+
+	if (atslave->dma_dev == chan->device->dev) {
+		chan->private = atslave;
+		return true;
+	} else {
+		return false;
+	}
+}
+
+static struct dma_chan *at_dma_xlate(struct of_phandle_args *dma_spec,
+				     struct of_dma *of_dma)
+{
+	struct dma_chan *chan;
+	struct at_dma_chan *atchan;
+	struct at_dma_slave *atslave;
+	dma_cap_mask_t mask;
+	unsigned int per_id;
+	struct platform_device *dmac_pdev;
+
+	if (dma_spec->args_count != 2)
+		return NULL;
+
+	dmac_pdev = of_find_device_by_node(dma_spec->np);
+	if (!dmac_pdev)
+		return NULL;
+
+	dma_cap_zero(mask);
+	dma_cap_set(DMA_SLAVE, mask);
+
+	atslave = kmalloc(sizeof(*atslave), GFP_KERNEL);
+	if (!atslave) {
+		put_device(&dmac_pdev->dev);
+		return NULL;
+	}
+
+	atslave->cfg = ATC_DST_H2SEL | ATC_SRC_H2SEL;
+	/*
+	 * We can fill both SRC_PER and DST_PER, one of these fields will be
+	 * ignored depending on DMA transfer direction.
+	 */
+	per_id = dma_spec->args[1] & AT91_DMA_CFG_PER_ID_MASK;
+	atslave->cfg |= ATC_DST_PER_ID(per_id) |  ATC_SRC_PER_ID(per_id);
+	/*
+	 * We have to translate the value we get from the device tree since
+	 * the half FIFO configuration value had to be 0 to keep backward
+	 * compatibility.
+	 */
+	switch (dma_spec->args[1] & AT91_DMA_CFG_FIFOCFG_MASK) {
+	case AT91_DMA_CFG_FIFOCFG_ALAP:
+		atslave->cfg |= FIELD_PREP(ATC_FIFOCFG,
+					   ATC_FIFOCFG_LARGESTBURST);
+		break;
+	case AT91_DMA_CFG_FIFOCFG_ASAP:
+		atslave->cfg |= FIELD_PREP(ATC_FIFOCFG,
+					   ATC_FIFOCFG_ENOUGHSPACE);
+		break;
+	case AT91_DMA_CFG_FIFOCFG_HALF:
+	default:
+		atslave->cfg |= FIELD_PREP(ATC_FIFOCFG, ATC_FIFOCFG_HALFFIFO);
+	}
+	atslave->dma_dev = &dmac_pdev->dev;
+
+	chan = dma_request_channel(mask, at_dma_filter, atslave);
+	if (!chan) {
+		put_device(&dmac_pdev->dev);
+		kfree(atslave);
+		return NULL;
+	}
+
+	atchan = to_at_dma_chan(chan);
+	atchan->per_if = dma_spec->args[0] & 0xff;
+	atchan->mem_if = (dma_spec->args[0] >> 16) & 0xff;
+
+	return chan;
+}
+#else
+static struct dma_chan *at_dma_xlate(struct of_phandle_args *dma_spec,
+				     struct of_dma *of_dma)
+{
+	return NULL;
+}
+#endif
+
+/*--  Module Management  -----------------------------------------------*/
+
+/* cap_mask is a multi-u32 bitfield, fill it with proper C code. */
+static struct at_dma_platform_data at91sam9rl_config = {
+	.nr_channels = 2,
+};
+static struct at_dma_platform_data at91sam9g45_config = {
+	.nr_channels = 8,
+};
+
+#if defined(CONFIG_OF)
+static const struct of_device_id atmel_dma_dt_ids[] = {
+	{
+		.compatible = "atmel,at91sam9rl-dma",
+		.data = &at91sam9rl_config,
+	}, {
+		.compatible = "atmel,at91sam9g45-dma",
+		.data = &at91sam9g45_config,
+	}, {
+		/* sentinel */
+	}
+};
+
+MODULE_DEVICE_TABLE(of, atmel_dma_dt_ids);
+#endif
+
+static const struct platform_device_id atdma_devtypes[] = {
+	{
+		.name = "at91sam9rl_dma",
+		.driver_data = (unsigned long) &at91sam9rl_config,
+	}, {
+		.name = "at91sam9g45_dma",
+		.driver_data = (unsigned long) &at91sam9g45_config,
+	}, {
+		/* sentinel */
+	}
+};
+
+static inline const struct at_dma_platform_data * __init at_dma_get_driver_data(
+						struct platform_device *pdev)
+{
+	if (pdev->dev.of_node) {
+		const struct of_device_id *match;
+		match = of_match_node(atmel_dma_dt_ids, pdev->dev.of_node);
+		if (match == NULL)
+			return NULL;
+		return match->data;
+	}
+	return (struct at_dma_platform_data *)
+			platform_get_device_id(pdev)->driver_data;
+}
+
+/**
+ * at_dma_off - disable DMA controller
+ * @atdma: the Atmel HDAMC device
+ */
+static void at_dma_off(struct at_dma *atdma)
+{
+	dma_writel(atdma, EN, 0);
+
+	/* disable all interrupts */
+	dma_writel(atdma, EBCIDR, -1L);
+
+	/* confirm that all channels are disabled */
+	while (dma_readl(atdma, CHSR) & atdma->all_chan_mask)
+		cpu_relax();
+}
+
+static int __init at_dma_probe(struct platform_device *pdev)
+{
+	struct at_dma		*atdma;
+	int			irq;
+	int			err;
+	int			i;
+	const struct at_dma_platform_data *plat_dat;
+
+	/* setup platform data for each SoC */
+	dma_cap_set(DMA_MEMCPY, at91sam9rl_config.cap_mask);
+	dma_cap_set(DMA_INTERLEAVE, at91sam9g45_config.cap_mask);
+	dma_cap_set(DMA_MEMCPY, at91sam9g45_config.cap_mask);
+	dma_cap_set(DMA_MEMSET, at91sam9g45_config.cap_mask);
+	dma_cap_set(DMA_MEMSET_SG, at91sam9g45_config.cap_mask);
+	dma_cap_set(DMA_PRIVATE, at91sam9g45_config.cap_mask);
+	dma_cap_set(DMA_SLAVE, at91sam9g45_config.cap_mask);
+
+	/* get DMA parameters from controller type */
+	plat_dat = at_dma_get_driver_data(pdev);
+	if (!plat_dat)
+		return -ENODEV;
+
+	atdma = devm_kzalloc(&pdev->dev,
+			     struct_size(atdma, chan, plat_dat->nr_channels),
+			     GFP_KERNEL);
+	if (!atdma)
+		return -ENOMEM;
+
+	atdma->regs = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(atdma->regs))
+		return PTR_ERR(atdma->regs);
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return irq;
+
+	/* discover transaction capabilities */
+	atdma->dma_device.cap_mask = plat_dat->cap_mask;
+	atdma->all_chan_mask = (1 << plat_dat->nr_channels) - 1;
+
+	atdma->clk = devm_clk_get(&pdev->dev, "dma_clk");
+	if (IS_ERR(atdma->clk))
+		return PTR_ERR(atdma->clk);
+
+	err = clk_prepare_enable(atdma->clk);
+	if (err)
+		return err;
+
+	/* force dma off, just in case */
+	at_dma_off(atdma);
+
+	err = request_irq(irq, at_dma_interrupt, 0, "at_hdmac", atdma);
+	if (err)
+		goto err_irq;
+
+	platform_set_drvdata(pdev, atdma);
+
+	/* create a pool of consistent memory blocks for hardware descriptors */
+	atdma->lli_pool = dma_pool_create("at_hdmac_lli_pool",
+					  &pdev->dev, sizeof(struct at_lli),
+					  4 /* word alignment */, 0);
+	if (!atdma->lli_pool) {
+		dev_err(&pdev->dev, "Unable to allocate DMA LLI descriptor pool\n");
+		err = -ENOMEM;
+		goto err_desc_pool_create;
+	}
+
+	/* create a pool of consistent memory blocks for memset blocks */
+	atdma->memset_pool = dma_pool_create("at_hdmac_memset_pool",
+					     &pdev->dev, sizeof(int), 4, 0);
+	if (!atdma->memset_pool) {
+		dev_err(&pdev->dev, "No memory for memset dma pool\n");
+		err = -ENOMEM;
+		goto err_memset_pool_create;
+	}
+
+	/* clear any pending interrupt */
+	while (dma_readl(atdma, EBCISR))
+		cpu_relax();
+
+	/* initialize channels related values */
+	INIT_LIST_HEAD(&atdma->dma_device.channels);
+	for (i = 0; i < plat_dat->nr_channels; i++) {
+		struct at_dma_chan	*atchan = &atdma->chan[i];
+
+		atchan->mem_if = AT_DMA_MEM_IF;
+		atchan->per_if = AT_DMA_PER_IF;
+
+		atchan->ch_regs = atdma->regs + ch_regs(i);
+		atchan->mask = 1 << i;
+
+		atchan->atdma = atdma;
+		atchan->vc.desc_free = atdma_desc_free;
+		vchan_init(&atchan->vc, &atdma->dma_device);
+		atc_enable_chan_irq(atdma, i);
+	}
+
+	/* set base routines */
+	atdma->dma_device.device_alloc_chan_resources = atc_alloc_chan_resources;
+	atdma->dma_device.device_free_chan_resources = atc_free_chan_resources;
+	atdma->dma_device.device_tx_status = atc_tx_status;
+	atdma->dma_device.device_issue_pending = atc_issue_pending;
+	atdma->dma_device.dev = &pdev->dev;
+
+	/* set prep routines based on capability */
+	if (dma_has_cap(DMA_INTERLEAVE, atdma->dma_device.cap_mask))
+		atdma->dma_device.device_prep_interleaved_dma = atc_prep_dma_interleaved;
+
+	if (dma_has_cap(DMA_MEMCPY, atdma->dma_device.cap_mask))
+		atdma->dma_device.device_prep_dma_memcpy = atc_prep_dma_memcpy;
+
+	if (dma_has_cap(DMA_MEMSET, atdma->dma_device.cap_mask)) {
+		atdma->dma_device.device_prep_dma_memset = atc_prep_dma_memset;
+		atdma->dma_device.device_prep_dma_memset_sg = atc_prep_dma_memset_sg;
+		atdma->dma_device.fill_align = DMAENGINE_ALIGN_4_BYTES;
+	}
+
+	if (dma_has_cap(DMA_SLAVE, atdma->dma_device.cap_mask)) {
+		atdma->dma_device.device_prep_slave_sg = atc_prep_slave_sg;
+		/* controller can do slave DMA: can trigger cyclic transfers */
+		dma_cap_set(DMA_CYCLIC, atdma->dma_device.cap_mask);
+		atdma->dma_device.device_prep_dma_cyclic = atc_prep_dma_cyclic;
+		atdma->dma_device.device_config = atc_config;
+		atdma->dma_device.device_pause = atc_pause;
+		atdma->dma_device.device_resume = atc_resume;
+		atdma->dma_device.device_terminate_all = atc_terminate_all;
+		atdma->dma_device.src_addr_widths = ATC_DMA_BUSWIDTHS;
+		atdma->dma_device.dst_addr_widths = ATC_DMA_BUSWIDTHS;
+		atdma->dma_device.directions = BIT(DMA_DEV_TO_MEM) | BIT(DMA_MEM_TO_DEV);
+		atdma->dma_device.residue_granularity = DMA_RESIDUE_GRANULARITY_BURST;
+	}
+
+	dma_writel(atdma, EN, AT_DMA_ENABLE);
+
+	dev_info(&pdev->dev, "Atmel AHB DMA Controller ( %s%s%s), %d channels\n",
+	  dma_has_cap(DMA_MEMCPY, atdma->dma_device.cap_mask) ? "cpy " : "",
+	  dma_has_cap(DMA_MEMSET, atdma->dma_device.cap_mask) ? "set " : "",
+	  dma_has_cap(DMA_SLAVE, atdma->dma_device.cap_mask)  ? "slave " : "",
+	  plat_dat->nr_channels);
+
+	err = dma_async_device_register(&atdma->dma_device);
+	if (err) {
+		dev_err(&pdev->dev, "Unable to register: %d.\n", err);
+		goto err_dma_async_device_register;
+	}
+
+	/*
+	 * Do not return an error if the dmac node is not present in order to
+	 * not break the existing way of requesting channel with
+	 * dma_request_channel().
+	 */
+	if (pdev->dev.of_node) {
+		err = of_dma_controller_register(pdev->dev.of_node,
+						 at_dma_xlate, atdma);
+		if (err) {
+			dev_err(&pdev->dev, "could not register of_dma_controller\n");
+			goto err_of_dma_controller_register;
+		}
+	}
+
+	return 0;
+
+err_of_dma_controller_register:
+	dma_async_device_unregister(&atdma->dma_device);
+err_dma_async_device_register:
+	dma_pool_destroy(atdma->memset_pool);
+err_memset_pool_create:
+	dma_pool_destroy(atdma->lli_pool);
+err_desc_pool_create:
+	free_irq(platform_get_irq(pdev, 0), atdma);
+err_irq:
+	clk_disable_unprepare(atdma->clk);
+	return err;
+}
+
+static int at_dma_remove(struct platform_device *pdev)
+{
+	struct at_dma		*atdma = platform_get_drvdata(pdev);
+	struct dma_chan		*chan, *_chan;
+
+	at_dma_off(atdma);
+	if (pdev->dev.of_node)
+		of_dma_controller_free(pdev->dev.of_node);
+	dma_async_device_unregister(&atdma->dma_device);
+
+	dma_pool_destroy(atdma->memset_pool);
+	dma_pool_destroy(atdma->lli_pool);
+	free_irq(platform_get_irq(pdev, 0), atdma);
+
+	list_for_each_entry_safe(chan, _chan, &atdma->dma_device.channels,
+			device_node) {
+		/* Disable interrupts */
+		atc_disable_chan_irq(atdma, chan->chan_id);
+		list_del(&chan->device_node);
+	}
+
+	clk_disable_unprepare(atdma->clk);
+
+	return 0;
+}
+
+static void at_dma_shutdown(struct platform_device *pdev)
+{
+	struct at_dma	*atdma = platform_get_drvdata(pdev);
+
+	at_dma_off(platform_get_drvdata(pdev));
+	clk_disable_unprepare(atdma->clk);
+}
+
+static int at_dma_prepare(struct device *dev)
+{
+	struct at_dma *atdma = dev_get_drvdata(dev);
+	struct dma_chan *chan, *_chan;
+
+	list_for_each_entry_safe(chan, _chan, &atdma->dma_device.channels,
+			device_node) {
+		struct at_dma_chan *atchan = to_at_dma_chan(chan);
+		/* wait for transaction completion (except in cyclic case) */
+		if (atc_chan_is_enabled(atchan) && !atc_chan_is_cyclic(atchan))
+			return -EAGAIN;
+	}
+	return 0;
+}
+
+static void atc_suspend_cyclic(struct at_dma_chan *atchan)
+{
+	struct dma_chan	*chan = &atchan->vc.chan;
+
+	/* Channel should be paused by user
+	 * do it anyway even if it is not done already */
+	if (!atc_chan_is_paused(atchan)) {
+		dev_warn(chan2dev(chan),
+		"cyclic channel not paused, should be done by channel user\n");
+		atc_pause(chan);
+	}
+
+	/* now preserve additional data for cyclic operations */
+	/* next descriptor address in the cyclic list */
+	atchan->save_dscr = channel_readl(atchan, DSCR);
+
+	vdbg_dump_regs(atchan);
+}
+
+static int at_dma_suspend_noirq(struct device *dev)
+{
+	struct at_dma *atdma = dev_get_drvdata(dev);
+	struct dma_chan *chan, *_chan;
+
+	/* preserve data */
+	list_for_each_entry_safe(chan, _chan, &atdma->dma_device.channels,
+			device_node) {
+		struct at_dma_chan *atchan = to_at_dma_chan(chan);
+
+		if (atc_chan_is_cyclic(atchan))
+			atc_suspend_cyclic(atchan);
+		atchan->save_cfg = channel_readl(atchan, CFG);
+	}
+	atdma->save_imr = dma_readl(atdma, EBCIMR);
+
+	/* disable DMA controller */
+	at_dma_off(atdma);
+	clk_disable_unprepare(atdma->clk);
+	return 0;
+}
+
+static void atc_resume_cyclic(struct at_dma_chan *atchan)
+{
+	struct at_dma	*atdma = to_at_dma(atchan->vc.chan.device);
+
+	/* restore channel status for cyclic descriptors list:
+	 * next descriptor in the cyclic list at the time of suspend */
+	channel_writel(atchan, SADDR, 0);
+	channel_writel(atchan, DADDR, 0);
+	channel_writel(atchan, CTRLA, 0);
+	channel_writel(atchan, CTRLB, 0);
+	channel_writel(atchan, DSCR, atchan->save_dscr);
+	dma_writel(atdma, CHER, atchan->mask);
+
+	/* channel pause status should be removed by channel user
+	 * We cannot take the initiative to do it here */
+
+	vdbg_dump_regs(atchan);
+}
+
+static int at_dma_resume_noirq(struct device *dev)
+{
+	struct at_dma *atdma = dev_get_drvdata(dev);
+	struct dma_chan *chan, *_chan;
+
+	/* bring back DMA controller */
+	clk_prepare_enable(atdma->clk);
+	dma_writel(atdma, EN, AT_DMA_ENABLE);
+
+	/* clear any pending interrupt */
+	while (dma_readl(atdma, EBCISR))
+		cpu_relax();
+
+	/* restore saved data */
+	dma_writel(atdma, EBCIER, atdma->save_imr);
+	list_for_each_entry_safe(chan, _chan, &atdma->dma_device.channels,
+			device_node) {
+		struct at_dma_chan *atchan = to_at_dma_chan(chan);
+
+		channel_writel(atchan, CFG, atchan->save_cfg);
+		if (atc_chan_is_cyclic(atchan))
+			atc_resume_cyclic(atchan);
+	}
+	return 0;
+}
+
+static const struct dev_pm_ops __maybe_unused at_dma_dev_pm_ops = {
+	.prepare = at_dma_prepare,
+	.suspend_noirq = at_dma_suspend_noirq,
+	.resume_noirq = at_dma_resume_noirq,
+};
+
+static struct platform_driver at_dma_driver = {
+	.remove		= at_dma_remove,
+	.shutdown	= at_dma_shutdown,
+	.id_table	= atdma_devtypes,
+	.driver = {
+		.name	= "at_hdmac",
+		.pm	= pm_ptr(&at_dma_dev_pm_ops),
+		.of_match_table	= of_match_ptr(atmel_dma_dt_ids),
+	},
+};
+
+static int __init at_dma_init(void)
+{
+	return platform_driver_probe(&at_dma_driver, at_dma_probe);
+}
+subsys_initcall(at_dma_init);
+
+static void __exit at_dma_exit(void)
+{
+	platform_driver_unregister(&at_dma_driver);
+}
+module_exit(at_dma_exit);
+
+MODULE_DESCRIPTION("Atmel AHB DMA Controller driver");
+MODULE_AUTHOR("Nicolas Ferre <nicolas.ferre@atmel.com>");
+MODULE_AUTHOR("Tudor Ambarus <tudor.ambarus@microchip.com>");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:at_hdmac");