dmaengine: add driver for Samsung s3c24xx SoCs

This adds a new driver to support the s3c24xx dma using the dmaengine
and makes the old one in mach-s3c24xx obsolete in the long run.

Conceptually the s3c24xx-dma feels like a distant relative of the pl08x
with numerous virtual channels being mapped to a lot less physical ones.
The driver therefore borrows a lot from the amba-pl08x driver in this
regard. Functionality-wise the driver gains a memcpy ability in addition
to the slave_sg one.

The driver supports both the method for requesting the peripheral used
by SoCs before the S3C2443 and the different method for S3C2443 and later.

On earlier SoCs the hardware channels usable for specific peripherals is
constrainted while on later SoCs all channels can be used for any peripheral.

Tested on a s3c2416-based board, memcpy using the dmatest module and
slave_sg partially using the spi-s3c64xx driver.
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>

drivers/dma/Kconfig

@@ -154,6 +154,18 @@ config TEGRA20_APB_DMA
 	  This DMA controller transfers data from memory to peripheral fifo
 	  or vice versa. It does not support memory to memory data transfer.
 
+config S3C24XX_DMAC
+	tristate "Samsung S3C24XX DMA support"
+	depends on ARCH_S3C24XX && !S3C24XX_DMA
+	select DMA_ENGINE
+	select DMA_VIRTUAL_CHANNELS
+	help
+	  Support for the Samsung S3C24XX DMA controller driver. The
+	  DMA controller is having multiple DMA channels which can be
+	  configured for different peripherals like audio, UART, SPI.
+	  The DMA controller can transfer data from memory to peripheral,
+	  periphal to memory, periphal to periphal and memory to memory.
+
 source "drivers/dma/sh/Kconfig"
 
 config COH901318

drivers/dma/Makefile

@@ -30,6 +30,7 @@ obj-$(CONFIG_SIRF_DMA) += sirf-dma.o
 obj-$(CONFIG_TI_EDMA) += edma.o
 obj-$(CONFIG_STE_DMA40) += ste_dma40.o ste_dma40_ll.o
 obj-$(CONFIG_TEGRA20_APB_DMA) += tegra20-apb-dma.o
+obj-$(CONFIG_S3C24XX_DMAC) += s3c24xx-dma.o
 obj-$(CONFIG_PL330_DMA) += pl330.o
 obj-$(CONFIG_PCH_DMA) += pch_dma.o
 obj-$(CONFIG_AMBA_PL08X) += amba-pl08x.o

drivers/dma/s3c24xx-dma.c

+/*
+ * S3C24XX DMA handling
+ *
+ * Copyright (c) 2013 Heiko Stuebner <heiko@sntech.de>
+ *
+ * based on amba-pl08x.c
+ *
+ * Copyright (c) 2006 ARM Ltd.
+ * Copyright (c) 2010 ST-Ericsson SA
+ *
+ * Author: Peter Pearse <peter.pearse@arm.com>
+ * Author: Linus Walleij <linus.walleij@stericsson.com>
+ *
+ * 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.
+ *
+ * The DMA controllers in S3C24XX SoCs have a varying number of DMA signals
+ * that can be routed to any of the 4 to 8 hardware-channels.
+ *
+ * Therefore on these DMA controllers the number of channels
+ * and the number of incoming DMA signals are two totally different things.
+ * It is usually not possible to theoretically handle all physical signals,
+ * so a multiplexing scheme with possible denial of use is necessary.
+ *
+ * Open items:
+ * - bursts
+ */
+
+#include <linux/platform_device.h>
+#include <linux/types.h>
+#include <linux/dmaengine.h>
+#include <linux/dma-mapping.h>
+#include <linux/interrupt.h>
+#include <linux/clk.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/platform_data/dma-s3c24xx.h>
+
+#include "dmaengine.h"
+#include "virt-dma.h"
+
+#define MAX_DMA_CHANNELS	8
+
+#define S3C24XX_DISRC			0x00
+#define S3C24XX_DISRCC			0x04
+#define S3C24XX_DISRCC_INC_INCREMENT	0
+#define S3C24XX_DISRCC_INC_FIXED	BIT(0)
+#define S3C24XX_DISRCC_LOC_AHB		0
+#define S3C24XX_DISRCC_LOC_APB		BIT(1)
+
+#define S3C24XX_DIDST			0x08
+#define S3C24XX_DIDSTC			0x0c
+#define S3C24XX_DIDSTC_INC_INCREMENT	0
+#define S3C24XX_DIDSTC_INC_FIXED	BIT(0)
+#define S3C24XX_DIDSTC_LOC_AHB		0
+#define S3C24XX_DIDSTC_LOC_APB		BIT(1)
+#define S3C24XX_DIDSTC_INT_TC0		0
+#define S3C24XX_DIDSTC_INT_RELOAD	BIT(2)
+
+#define S3C24XX_DCON			0x10
+
+#define S3C24XX_DCON_TC_MASK		0xfffff
+#define S3C24XX_DCON_DSZ_BYTE		(0 << 20)
+#define S3C24XX_DCON_DSZ_HALFWORD	(1 << 20)
+#define S3C24XX_DCON_DSZ_WORD		(2 << 20)
+#define S3C24XX_DCON_DSZ_MASK		(3 << 20)
+#define S3C24XX_DCON_DSZ_SHIFT		20
+#define S3C24XX_DCON_AUTORELOAD		0
+#define S3C24XX_DCON_NORELOAD		BIT(22)
+#define S3C24XX_DCON_HWTRIG		BIT(23)
+#define S3C24XX_DCON_HWSRC_SHIFT	24
+#define S3C24XX_DCON_SERV_SINGLE	0
+#define S3C24XX_DCON_SERV_WHOLE		BIT(27)
+#define S3C24XX_DCON_TSZ_UNIT		0
+#define S3C24XX_DCON_TSZ_BURST4		BIT(28)
+#define S3C24XX_DCON_INT		BIT(29)
+#define S3C24XX_DCON_SYNC_PCLK		0
+#define S3C24XX_DCON_SYNC_HCLK		BIT(30)
+#define S3C24XX_DCON_DEMAND		0
+#define S3C24XX_DCON_HANDSHAKE		BIT(31)
+
+#define S3C24XX_DSTAT			0x14
+#define S3C24XX_DSTAT_STAT_BUSY		BIT(20)
+#define S3C24XX_DSTAT_CURRTC_MASK	0xfffff
+
+#define S3C24XX_DMASKTRIG		0x20
+#define S3C24XX_DMASKTRIG_SWTRIG	BIT(0)
+#define S3C24XX_DMASKTRIG_ON		BIT(1)
+#define S3C24XX_DMASKTRIG_STOP		BIT(2)
+
+#define S3C24XX_DMAREQSEL		0x24
+#define S3C24XX_DMAREQSEL_HW		BIT(0)
+
+/*
+ * S3C2410, S3C2440 and S3C2442 SoCs cannot select any physical channel
+ * for a DMA source. Instead only specific channels are valid.
+ * All of these SoCs have 4 physical channels and the number of request
+ * source bits is 3. Additionally we also need 1 bit to mark the channel
+ * as valid.
+ * Therefore we separate the chansel element of the channel data into 4
+ * parts of 4 bits each, to hold the information if the channel is valid
+ * and the hw request source to use.
+ *
+ * Example:
+ * SDI is valid on channels 0, 2 and 3 - with varying hw request sources.
+ * For it the chansel field would look like
+ *
+ * ((BIT(3) | 1) << 3 * 4) | // channel 3, with request source 1
+ * ((BIT(3) | 2) << 2 * 4) | // channel 2, with request source 2
+ * ((BIT(3) | 2) << 0 * 4)   // channel 0, with request source 2
+ */
+#define S3C24XX_CHANSEL_WIDTH		4
+#define S3C24XX_CHANSEL_VALID		BIT(3)
+#define S3C24XX_CHANSEL_REQ_MASK	7
+
+/*
+ * struct soc_data - vendor-specific config parameters for individual SoCs
+ * @stride: spacing between the registers of each channel
+ * @has_reqsel: does the controller use the newer requestselection mechanism
+ * @has_clocks: are controllable dma-clocks present
+ */
+struct soc_data {
+	int stride;
+	bool has_reqsel;
+	bool has_clocks;
+};
+
+/*
+ * enum s3c24xx_dma_chan_state - holds the virtual channel states
+ * @S3C24XX_DMA_CHAN_IDLE: the channel is idle
+ * @S3C24XX_DMA_CHAN_RUNNING: the channel has allocated a physical transport
+ * channel and is running a transfer on it
+ * @S3C24XX_DMA_CHAN_WAITING: the channel is waiting for a physical transport
+ * channel to become available (only pertains to memcpy channels)
+ */
+enum s3c24xx_dma_chan_state {
+	S3C24XX_DMA_CHAN_IDLE,
+	S3C24XX_DMA_CHAN_RUNNING,
+	S3C24XX_DMA_CHAN_WAITING,
+};
+
+/*
+ * struct s3c24xx_sg - structure containing data per sg
+ * @src_addr: src address of sg
+ * @dst_addr: dst address of sg
+ * @len: transfer len in bytes
+ * @node: node for txd's dsg_list
+ */
+struct s3c24xx_sg {
+	dma_addr_t src_addr;
+	dma_addr_t dst_addr;
+	size_t len;
+	struct list_head node;
+};
+
+/*
+ * struct s3c24xx_txd - wrapper for struct dma_async_tx_descriptor
+ * @vd: virtual DMA descriptor
+ * @dsg_list: list of children sg's
+ * @at: sg currently being transfered
+ * @width: transfer width
+ * @disrcc: value for source control register
+ * @didstc: value for destination control register
+ * @dcon: base value for dcon register
+ */
+struct s3c24xx_txd {
+	struct virt_dma_desc vd;
+	struct list_head dsg_list;
+	struct list_head *at;
+	u8 width;
+	u32 disrcc;
+	u32 didstc;
+	u32 dcon;
+};
+
+struct s3c24xx_dma_chan;
+
+/*
+ * struct s3c24xx_dma_phy - holder for the physical channels
+ * @id: physical index to this channel
+ * @valid: does the channel have all required elements
+ * @base: virtual memory base (remapped) for the this channel
+ * @irq: interrupt for this channel
+ * @clk: clock for this channel
+ * @lock: a lock to use when altering an instance of this struct
+ * @serving: virtual channel currently being served by this physicalchannel
+ * @host: a pointer to the host (internal use)
+ */
+struct s3c24xx_dma_phy {
+	unsigned int			id;
+	bool				valid;
+	void __iomem			*base;
+	unsigned int			irq;
+	struct clk			*clk;
+	spinlock_t			lock;
+	struct s3c24xx_dma_chan		*serving;
+	struct s3c24xx_dma_engine	*host;
+};
+
+/*
+ * struct s3c24xx_dma_chan - this structure wraps a DMA ENGINE channel
+ * @id: the id of the channel
+ * @name: name of the channel
+ * @vc: wrappped virtual channel
+ * @phy: the physical channel utilized by this channel, if there is one
+ * @runtime_addr: address for RX/TX according to the runtime config
+ * @at: active transaction on this channel
+ * @lock: a lock for this channel data
+ * @host: a pointer to the host (internal use)
+ * @state: whether the channel is idle, running etc
+ * @slave: whether this channel is a device (slave) or for memcpy
+ */
+struct s3c24xx_dma_chan {
+	int id;
+	const char *name;
+	struct virt_dma_chan vc;
+	struct s3c24xx_dma_phy *phy;
+	struct dma_slave_config cfg;
+	struct s3c24xx_txd *at;
+	struct s3c24xx_dma_engine *host;
+	enum s3c24xx_dma_chan_state state;
+	bool slave;
+};
+
+/*
+ * struct s3c24xx_dma_engine - the local state holder for the S3C24XX
+ * @pdev: the corresponding platform device
+ * @pdata: platform data passed in from the platform/machine
+ * @base: virtual memory base (remapped)
+ * @slave: slave engine for this instance
+ * @memcpy: memcpy engine for this instance
+ * @phy_chans: array of data for the physical channels
+ */
+struct s3c24xx_dma_engine {
+	struct platform_device			*pdev;
+	const struct s3c24xx_dma_platdata	*pdata;
+	struct soc_data				*sdata;
+	void __iomem				*base;
+	struct dma_device			slave;
+	struct dma_device			memcpy;
+	struct s3c24xx_dma_phy			*phy_chans;
+};
+
+/*
+ * Physical channel handling
+ */
+
+/*
+ * Check whether a certain channel is busy or not.
+ */
+static int s3c24xx_dma_phy_busy(struct s3c24xx_dma_phy *phy)
+{
+	unsigned int val = readl(phy->base + S3C24XX_DSTAT);
+	return val & S3C24XX_DSTAT_STAT_BUSY;
+}
+
+static bool s3c24xx_dma_phy_valid(struct s3c24xx_dma_chan *s3cchan,
+				  struct s3c24xx_dma_phy *phy)
+{
+	struct s3c24xx_dma_engine *s3cdma = s3cchan->host;
+	const struct s3c24xx_dma_platdata *pdata = s3cdma->pdata;
+	struct s3c24xx_dma_channel *cdata = &pdata->channels[s3cchan->id];
+	int phyvalid;
+
+	/* every phy is valid for memcopy channels */
+	if (!s3cchan->slave)
+		return true;
+
+	/* On newer variants all phys can be used for all virtual channels */
+	if (s3cdma->sdata->has_reqsel)
+		return true;
+
+	phyvalid = (cdata->chansel >> (phy->id * S3C24XX_CHANSEL_WIDTH));
+	return (phyvalid & S3C24XX_CHANSEL_VALID) ? true : false;
+}
+
+/*
+ * Allocate a physical channel for a virtual channel
+ *
+ * Try to locate a physical channel to be used for this transfer. If all
+ * are taken return NULL and the requester will have to cope by using
+ * some fallback PIO mode or retrying later.
+ */
+static
+struct s3c24xx_dma_phy *s3c24xx_dma_get_phy(struct s3c24xx_dma_chan *s3cchan)
+{
+	struct s3c24xx_dma_engine *s3cdma = s3cchan->host;
+	const struct s3c24xx_dma_platdata *pdata = s3cdma->pdata;
+	struct s3c24xx_dma_channel *cdata;
+	struct s3c24xx_dma_phy *phy = NULL;
+	unsigned long flags;
+	int i;
+	int ret;
+
+	if (s3cchan->slave)
+		cdata = &pdata->channels[s3cchan->id];
+
+	for (i = 0; i < s3cdma->pdata->num_phy_channels; i++) {
+		phy = &s3cdma->phy_chans[i];
+
+		if (!phy->valid)
+			continue;
+
+		if (!s3c24xx_dma_phy_valid(s3cchan, phy))
+			continue;
+
+		spin_lock_irqsave(&phy->lock, flags);
+
+		if (!phy->serving) {
+			phy->serving = s3cchan;
+			spin_unlock_irqrestore(&phy->lock, flags);
+			break;
+		}
+
+		spin_unlock_irqrestore(&phy->lock, flags);
+	}
+
+	/* No physical channel available, cope with it */
+	if (i == s3cdma->pdata->num_phy_channels) {
+		dev_warn(&s3cdma->pdev->dev, "no phy channel available\n");
+		return NULL;
+	}
+
+	/* start the phy clock */
+	if (s3cdma->sdata->has_clocks) {
+		ret = clk_enable(phy->clk);
+		if (ret) {
+			dev_err(&s3cdma->pdev->dev, "could not enable clock for channel %d, err %d\n",
+				phy->id, ret);
+			phy->serving = NULL;
+			return NULL;
+		}
+	}
+
+	return phy;
+}
+
+/*
+ * Mark the physical channel as free.
+ *
+ * This drops the link between the physical and virtual channel.
+ */
+static inline void s3c24xx_dma_put_phy(struct s3c24xx_dma_phy *phy)
+{
+	struct s3c24xx_dma_engine *s3cdma = phy->host;
+
+	if (s3cdma->sdata->has_clocks)
+		clk_disable(phy->clk);
+
+	phy->serving = NULL;
+}
+
+/*
+ * Stops the channel by writing the stop bit.
+ * This should not be used for an on-going transfer, but as a method of
+ * shutting down a channel (eg, when it's no longer used) or terminating a
+ * transfer.
+ */
+static void s3c24xx_dma_terminate_phy(struct s3c24xx_dma_phy *phy)
+{
+	writel(S3C24XX_DMASKTRIG_STOP, phy->base + S3C24XX_DMASKTRIG);
+}
+
+/*
+ * Virtual channel handling
+ */
+
+static inline
+struct s3c24xx_dma_chan *to_s3c24xx_dma_chan(struct dma_chan *chan)
+{
+	return container_of(chan, struct s3c24xx_dma_chan, vc.chan);
+}
+
+static u32 s3c24xx_dma_getbytes_chan(struct s3c24xx_dma_chan *s3cchan)
+{
+	struct s3c24xx_dma_phy *phy = s3cchan->phy;
+	struct s3c24xx_txd *txd = s3cchan->at;
+	u32 tc = readl(phy->base + S3C24XX_DSTAT) & S3C24XX_DSTAT_CURRTC_MASK;
+
+	return tc * txd->width;
+}
+
+static int s3c24xx_dma_set_runtime_config(struct s3c24xx_dma_chan *s3cchan,
+				  struct dma_slave_config *config)
+{
+	if (!s3cchan->slave)
+		return -EINVAL;
+
+	/* Reject definitely invalid configurations */
+	if (config->src_addr_width == DMA_SLAVE_BUSWIDTH_8_BYTES ||
+	    config->dst_addr_width == DMA_SLAVE_BUSWIDTH_8_BYTES)
+		return -EINVAL;
+
+	s3cchan->cfg = *config;
+
+	return 0;
+}
+
+/*
+ * Transfer handling
+ */
+
+static inline
+struct s3c24xx_txd *to_s3c24xx_txd(struct dma_async_tx_descriptor *tx)
+{
+	return container_of(tx, struct s3c24xx_txd, vd.tx);
+}
+
+static struct s3c24xx_txd *s3c24xx_dma_get_txd(void)
+{
+	struct s3c24xx_txd *txd = kzalloc(sizeof(*txd), GFP_NOWAIT);
+
+	if (txd) {
+		INIT_LIST_HEAD(&txd->dsg_list);
+		txd->dcon = S3C24XX_DCON_INT | S3C24XX_DCON_NORELOAD;
+	}
+
+	return txd;
+}
+
+static void s3c24xx_dma_free_txd(struct s3c24xx_txd *txd)
+{
+	struct s3c24xx_sg *dsg, *_dsg;
+
+	list_for_each_entry_safe(dsg, _dsg, &txd->dsg_list, node) {
+		list_del(&dsg->node);
+		kfree(dsg);
+	}
+
+	kfree(txd);
+}
+
+static void s3c24xx_dma_start_next_sg(struct s3c24xx_dma_chan *s3cchan,
+				       struct s3c24xx_txd *txd)
+{
+	struct s3c24xx_dma_engine *s3cdma = s3cchan->host;
+	struct s3c24xx_dma_phy *phy = s3cchan->phy;
+	const struct s3c24xx_dma_platdata *pdata = s3cdma->pdata;
+	struct s3c24xx_sg *dsg = list_entry(txd->at, struct s3c24xx_sg, node);
+	u32 dcon = txd->dcon;
+	u32 val;
+
+	/* transfer-size and -count from len and width */
+	switch (txd->width) {
+	case 1:
+		dcon |= S3C24XX_DCON_DSZ_BYTE | dsg->len;
+		break;
+	case 2:
+		dcon |= S3C24XX_DCON_DSZ_HALFWORD | (dsg->len / 2);
+		break;
+	case 4:
+		dcon |= S3C24XX_DCON_DSZ_WORD | (dsg->len / 4);
+		break;
+	}
+
+	if (s3cchan->slave) {
+		struct s3c24xx_dma_channel *cdata =
+					&pdata->channels[s3cchan->id];
+
+		if (s3cdma->sdata->has_reqsel) {
+			writel_relaxed((cdata->chansel << 1) |
+							S3C24XX_DMAREQSEL_HW,
+					phy->base + S3C24XX_DMAREQSEL);
+		} else {
+			int csel = cdata->chansel >> (phy->id *
+							S3C24XX_CHANSEL_WIDTH);
+
+			csel &= S3C24XX_CHANSEL_REQ_MASK;
+			dcon |= csel << S3C24XX_DCON_HWSRC_SHIFT;
+			dcon |= S3C24XX_DCON_HWTRIG;
+		}
+	} else {
+		if (s3cdma->sdata->has_reqsel)
+			writel_relaxed(0, phy->base + S3C24XX_DMAREQSEL);
+	}
+
+	writel_relaxed(dsg->src_addr, phy->base + S3C24XX_DISRC);
+	writel_relaxed(txd->disrcc, phy->base + S3C24XX_DISRCC);
+	writel_relaxed(dsg->dst_addr, phy->base + S3C24XX_DIDST);
+	writel_relaxed(txd->didstc, phy->base + S3C24XX_DIDSTC);
+	writel_relaxed(dcon, phy->base + S3C24XX_DCON);
+
+	val = readl_relaxed(phy->base + S3C24XX_DMASKTRIG);
+	val &= ~S3C24XX_DMASKTRIG_STOP;
+	val |= S3C24XX_DMASKTRIG_ON;
+
+	/* trigger the dma operation for memcpy transfers */
+	if (!s3cchan->slave)
+		val |= S3C24XX_DMASKTRIG_SWTRIG;
+
+	writel(val, phy->base + S3C24XX_DMASKTRIG);
+}
+
+/*
+ * Set the initial DMA register values and start first sg.
+ */
+static void s3c24xx_dma_start_next_txd(struct s3c24xx_dma_chan *s3cchan)
+{
+	struct s3c24xx_dma_phy *phy = s3cchan->phy;
+	struct virt_dma_desc *vd = vchan_next_desc(&s3cchan->vc);
+	struct s3c24xx_txd *txd = to_s3c24xx_txd(&vd->tx);
+
+	list_del(&txd->vd.node);
+
+	s3cchan->at = txd;
+
+	/* Wait for channel inactive */
+	while (s3c24xx_dma_phy_busy(phy))
+		cpu_relax();
+
+	/* point to the first element of the sg list */
+	txd->at = txd->dsg_list.next;
+	s3c24xx_dma_start_next_sg(s3cchan, txd);
+}
+
+static void s3c24xx_dma_free_txd_list(struct s3c24xx_dma_engine *s3cdma,
+				struct s3c24xx_dma_chan *s3cchan)
+{
+	LIST_HEAD(head);
+
+	vchan_get_all_descriptors(&s3cchan->vc, &head);
+	vchan_dma_desc_free_list(&s3cchan->vc, &head);
+}
+
+/*
+ * Try to allocate a physical channel.  When successful, assign it to
+ * this virtual channel, and initiate the next descriptor.  The
+ * virtual channel lock must be held at this point.
+ */
+static void s3c24xx_dma_phy_alloc_and_start(struct s3c24xx_dma_chan *s3cchan)
+{
+	struct s3c24xx_dma_engine *s3cdma = s3cchan->host;
+	struct s3c24xx_dma_phy *phy;
+
+	phy = s3c24xx_dma_get_phy(s3cchan);
+	if (!phy) {
+		dev_dbg(&s3cdma->pdev->dev, "no physical channel available for xfer on %s\n",
+			s3cchan->name);
+		s3cchan->state = S3C24XX_DMA_CHAN_WAITING;
+		return;
+	}
+
+	dev_dbg(&s3cdma->pdev->dev, "allocated physical channel %d for xfer on %s\n",
+		phy->id, s3cchan->name);
+
+	s3cchan->phy = phy;
+	s3cchan->state = S3C24XX_DMA_CHAN_RUNNING;
+
+	s3c24xx_dma_start_next_txd(s3cchan);
+}
+
+static void s3c24xx_dma_phy_reassign_start(struct s3c24xx_dma_phy *phy,
+	struct s3c24xx_dma_chan *s3cchan)
+{
+	struct s3c24xx_dma_engine *s3cdma = s3cchan->host;
+
+	dev_dbg(&s3cdma->pdev->dev, "reassigned physical channel %d for xfer on %s\n",
+		phy->id, s3cchan->name);
+
+	/*
+	 * We do this without taking the lock; we're really only concerned
+	 * about whether this pointer is NULL or not, and we're guaranteed
+	 * that this will only be called when it _already_ is non-NULL.
+	 */
+	phy->serving = s3cchan;
+	s3cchan->phy = phy;
+	s3cchan->state = S3C24XX_DMA_CHAN_RUNNING;
+	s3c24xx_dma_start_next_txd(s3cchan);
+}
+
+/*
+ * Free a physical DMA channel, potentially reallocating it to another
+ * virtual channel if we have any pending.
+ */
+static void s3c24xx_dma_phy_free(struct s3c24xx_dma_chan *s3cchan)
+{
+	struct s3c24xx_dma_engine *s3cdma = s3cchan->host;
+	struct s3c24xx_dma_chan *p, *next;
+
+retry:
+	next = NULL;
+
+	/* Find a waiting virtual channel for the next transfer. */
+	list_for_each_entry(p, &s3cdma->memcpy.channels, vc.chan.device_node)
+		if (p->state == S3C24XX_DMA_CHAN_WAITING) {
+			next = p;
+			break;
+		}
+
+	if (!next) {
+		list_for_each_entry(p, &s3cdma->slave.channels,
+				    vc.chan.device_node)
+			if (p->state == S3C24XX_DMA_CHAN_WAITING &&
+				      s3c24xx_dma_phy_valid(p, s3cchan->phy)) {
+				next = p;
+				break;
+			}
+	}
+
+	/* Ensure that the physical channel is stopped */
+	s3c24xx_dma_terminate_phy(s3cchan->phy);
+
+	if (next) {
+		bool success;
+
+		/*
+		 * Eww.  We know this isn't going to deadlock
+		 * but lockdep probably doesn't.
+		 */
+		spin_lock(&next->vc.lock);
+		/* Re-check the state now that we have the lock */
+		success = next->state == S3C24XX_DMA_CHAN_WAITING;
+		if (success)
+			s3c24xx_dma_phy_reassign_start(s3cchan->phy, next);
+		spin_unlock(&next->vc.lock);
+
+		/* If the state changed, try to find another channel */
+		if (!success)
+			goto retry;
+	} else {
+		/* No more jobs, so free up the physical channel */
+		s3c24xx_dma_put_phy(s3cchan->phy);
+	}
+
+	s3cchan->phy = NULL;
+	s3cchan->state = S3C24XX_DMA_CHAN_IDLE;
+}
+
+static void s3c24xx_dma_unmap_buffers(struct s3c24xx_txd *txd)
+{
+	struct device *dev = txd->vd.tx.chan->device->dev;
+	struct s3c24xx_sg *dsg;
+
+	if (!(txd->vd.tx.flags & DMA_COMPL_SKIP_SRC_UNMAP)) {
+		if (txd->vd.tx.flags & DMA_COMPL_SRC_UNMAP_SINGLE)
+			list_for_each_entry(dsg, &txd->dsg_list, node)
+				dma_unmap_single(dev, dsg->src_addr, dsg->len,
+						DMA_TO_DEVICE);
+		else {
+			list_for_each_entry(dsg, &txd->dsg_list, node)
+				dma_unmap_page(dev, dsg->src_addr, dsg->len,
+						DMA_TO_DEVICE);
+		}
+	}
+
+	if (!(txd->vd.tx.flags & DMA_COMPL_SKIP_DEST_UNMAP)) {
+		if (txd->vd.tx.flags & DMA_COMPL_DEST_UNMAP_SINGLE)
+			list_for_each_entry(dsg, &txd->dsg_list, node)
+				dma_unmap_single(dev, dsg->dst_addr, dsg->len,
+						DMA_FROM_DEVICE);
+		else
+			list_for_each_entry(dsg, &txd->dsg_list, node)
+				dma_unmap_page(dev, dsg->dst_addr, dsg->len,
+						DMA_FROM_DEVICE);
+	}
+}
+
+static void s3c24xx_dma_desc_free(struct virt_dma_desc *vd)
+{
+	struct s3c24xx_txd *txd = to_s3c24xx_txd(&vd->tx);
+	struct s3c24xx_dma_chan *s3cchan = to_s3c24xx_dma_chan(vd->tx.chan);
+
+	if (!s3cchan->slave)
+		s3c24xx_dma_unmap_buffers(txd);
+
+	s3c24xx_dma_free_txd(txd);
+}
+
+static irqreturn_t s3c24xx_dma_irq(int irq, void *data)
+{
+	struct s3c24xx_dma_phy *phy = data;
+	struct s3c24xx_dma_chan *s3cchan = phy->serving;
+	struct s3c24xx_txd *txd;
+
+	dev_dbg(&phy->host->pdev->dev, "interrupt on channel %d\n", phy->id);
+
+	/*
+	 * Interrupts happen to notify the completion of a transfer and the
+	 * channel should have moved into its stop state already on its own.
+	 * Therefore interrupts on channels not bound to a virtual channel
+	 * should never happen. Nevertheless send a terminate command to the
+	 * channel if the unlikely case happens.
+	 */
+	if (unlikely(!s3cchan)) {
+		dev_err(&phy->host->pdev->dev, "interrupt on unused channel %d\n",
+			phy->id);
+
+		s3c24xx_dma_terminate_phy(phy);
+
+		return IRQ_HANDLED;
+	}
+
+	spin_lock(&s3cchan->vc.lock);
+	txd = s3cchan->at;
+	if (txd) {
+		/* when more sg's are in this txd, start the next one */
+		if (!list_is_last(txd->at, &txd->dsg_list)) {
+			txd->at = txd->at->next;
+			s3c24xx_dma_start_next_sg(s3cchan, txd);
+		} else {
+			s3cchan->at = NULL;
+			vchan_cookie_complete(&txd->vd);
+
+			/*
+			 * And start the next descriptor (if any),
+			 * otherwise free this channel.
+			 */
+			if (vchan_next_desc(&s3cchan->vc))
+				s3c24xx_dma_start_next_txd(s3cchan);
+			else
+				s3c24xx_dma_phy_free(s3cchan);
+		}
+	}
+	spin_unlock(&s3cchan->vc.lock);
+
+	return IRQ_HANDLED;
+}
+
+/*
+ * The DMA ENGINE API
+ */
+
+static int s3c24xx_dma_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
+			 unsigned long arg)
+{
+	struct s3c24xx_dma_chan *s3cchan = to_s3c24xx_dma_chan(chan);
+	struct s3c24xx_dma_engine *s3cdma = s3cchan->host;
+	unsigned long flags;
+	int ret = 0;
+
+	spin_lock_irqsave(&s3cchan->vc.lock, flags);
+
+	switch (cmd) {
+	case DMA_SLAVE_CONFIG:
+		ret = s3c24xx_dma_set_runtime_config(s3cchan,
+					      (struct dma_slave_config *)arg);
+		break;
+	case DMA_TERMINATE_ALL:
+		if (!s3cchan->phy && !s3cchan->at) {
+			dev_err(&s3cdma->pdev->dev, "trying to terminate already stopped channel %d\n",
+				s3cchan->id);
+			ret = -EINVAL;
+			break;
+		}
+
+		s3cchan->state = S3C24XX_DMA_CHAN_IDLE;
+
+		 /* Mark physical channel as free */
+		if (s3cchan->phy)
+			s3c24xx_dma_phy_free(s3cchan);
+
+		/* Dequeue current job */
+		if (s3cchan->at) {
+			s3c24xx_dma_desc_free(&s3cchan->at->vd);
+			s3cchan->at = NULL;
+		}
+
+		/* Dequeue jobs not yet fired as well */
+		s3c24xx_dma_free_txd_list(s3cdma, s3cchan);
+		break;
+	default:
+		/* Unknown command */
+		ret = -ENXIO;
+		break;
+	}
+
+	spin_unlock_irqrestore(&s3cchan->vc.lock, flags);
+
+	return ret;
+}
+
+static int s3c24xx_dma_alloc_chan_resources(struct dma_chan *chan)
+{
+	return 0;
+}
+
+static void s3c24xx_dma_free_chan_resources(struct dma_chan *chan)
+{
+	/* Ensure all queued descriptors are freed */
+	vchan_free_chan_resources(to_virt_chan(chan));
+}
+
+static enum dma_status s3c24xx_dma_tx_status(struct dma_chan *chan,
+		dma_cookie_t cookie, struct dma_tx_state *txstate)
+{
+	struct s3c24xx_dma_chan *s3cchan = to_s3c24xx_dma_chan(chan);
+	struct s3c24xx_txd *txd;
+	struct s3c24xx_sg *dsg;
+	struct virt_dma_desc *vd;
+	unsigned long flags;
+	enum dma_status ret;
+	size_t bytes = 0;
+
+	spin_lock_irqsave(&s3cchan->vc.lock, flags);
+	ret = dma_cookie_status(chan, cookie, txstate);
+	if (ret == DMA_SUCCESS) {
+		spin_unlock_irqrestore(&s3cchan->vc.lock, flags);
+		return ret;
+	}
+
+	/*
+	 * There's no point calculating the residue if there's
+	 * no txstate to store the value.
+	 */
+	if (!txstate) {
+		spin_unlock_irqrestore(&s3cchan->vc.lock, flags);
+		return ret;
+	}
+
+	vd = vchan_find_desc(&s3cchan->vc, cookie);
+	if (vd) {
+		/* On the issued list, so hasn't been processed yet */
+		txd = to_s3c24xx_txd(&vd->tx);
+
+		list_for_each_entry(dsg, &txd->dsg_list, node)
+			bytes += dsg->len;
+	} else {
+		/*
+		 * Currently running, so sum over the pending sg's and
+		 * the currently active one.
+		 */
+		txd = s3cchan->at;
+
+		dsg = list_entry(txd->at, struct s3c24xx_sg, node);
+		list_for_each_entry_from(dsg, &txd->dsg_list, node)
+			bytes += dsg->len;
+
+		bytes += s3c24xx_dma_getbytes_chan(s3cchan);
+	}
+	spin_unlock_irqrestore(&s3cchan->vc.lock, flags);
+
+	/*
+	 * This cookie not complete yet
+	 * Get number of bytes left in the active transactions and queue
+	 */
+	dma_set_residue(txstate, bytes);
+
+	/* Whether waiting or running, we're in progress */
+	return ret;
+}
+
+/*
+ * Initialize a descriptor to be used by memcpy submit
+ */
+static struct dma_async_tx_descriptor *s3c24xx_dma_prep_memcpy(
+		struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
+		size_t len, unsigned long flags)
+{
+	struct s3c24xx_dma_chan *s3cchan = to_s3c24xx_dma_chan(chan);
+	struct s3c24xx_dma_engine *s3cdma = s3cchan->host;
+	struct s3c24xx_txd *txd;
+	struct s3c24xx_sg *dsg;
+	int src_mod, dest_mod;
+
+	dev_dbg(&s3cdma->pdev->dev, "prepare memcpy of %d bytes from %s\n",
+			len, s3cchan->name);
+
+	if ((len & S3C24XX_DCON_TC_MASK) != len) {
+		dev_err(&s3cdma->pdev->dev, "memcpy size %d to large\n", len);
+		return NULL;
+	}
+
+	txd = s3c24xx_dma_get_txd();
+	if (!txd)
+		return NULL;
+
+	dsg = kzalloc(sizeof(*dsg), GFP_NOWAIT);
+	if (!dsg) {
+		s3c24xx_dma_free_txd(txd);
+		return NULL;
+	}
+	list_add_tail(&dsg->node, &txd->dsg_list);
+
+	dsg->src_addr = src;
+	dsg->dst_addr = dest;
+	dsg->len = len;
+
+	/*
+	 * Determine a suitable transfer width.
+	 * The DMA controller cannot fetch/store information which is not
+	 * naturally aligned on the bus, i.e., a 4 byte fetch must start at
+	 * an address divisible by 4 - more generally addr % width must be 0.
+	 */
+	src_mod = src % 4;
+	dest_mod = dest % 4;
+	switch (len % 4) {
+	case 0:
+		txd->width = (src_mod == 0 && dest_mod == 0) ? 4 : 1;
+		break;
+	case 2:
+		txd->width = ((src_mod == 2 || src_mod == 0) &&
+			      (dest_mod == 2 || dest_mod == 0)) ? 2 : 1;
+		break;
+	default:
+		txd->width = 1;
+		break;
+	}
+
+	txd->disrcc = S3C24XX_DISRCC_LOC_AHB | S3C24XX_DISRCC_INC_INCREMENT;
+	txd->didstc = S3C24XX_DIDSTC_LOC_AHB | S3C24XX_DIDSTC_INC_INCREMENT;
+	txd->dcon |= S3C24XX_DCON_DEMAND | S3C24XX_DCON_SYNC_HCLK |
+		     S3C24XX_DCON_SERV_WHOLE;
+
+	return vchan_tx_prep(&s3cchan->vc, &txd->vd, flags);
+}
+
+static struct dma_async_tx_descriptor *s3c24xx_dma_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 s3c24xx_dma_chan *s3cchan = to_s3c24xx_dma_chan(chan);
+	struct s3c24xx_dma_engine *s3cdma = s3cchan->host;
+	const struct s3c24xx_dma_platdata *pdata = s3cdma->pdata;
+	struct s3c24xx_dma_channel *cdata = &pdata->channels[s3cchan->id];
+	struct s3c24xx_txd *txd;
+	struct s3c24xx_sg *dsg;
+	struct scatterlist *sg;
+	dma_addr_t slave_addr;
+	u32 hwcfg = 0;
+	int tmp;
+
+	dev_dbg(&s3cdma->pdev->dev, "prepare transaction of %d bytes from %s\n",
+			sg_dma_len(sgl), s3cchan->name);
+
+	txd = s3c24xx_dma_get_txd();
+	if (!txd)
+		return NULL;
+
+	if (cdata->handshake)
+		txd->dcon |= S3C24XX_DCON_HANDSHAKE;
+
+	switch (cdata->bus) {
+	case S3C24XX_DMA_APB:
+		txd->dcon |= S3C24XX_DCON_SYNC_PCLK;
+		hwcfg |= S3C24XX_DISRCC_LOC_APB;
+		break;
+	case S3C24XX_DMA_AHB:
+		txd->dcon |= S3C24XX_DCON_SYNC_HCLK;
+		hwcfg |= S3C24XX_DISRCC_LOC_AHB;
+		break;
+	}
+
+	/*
+	 * Always assume our peripheral desintation is a fixed
+	 * address in memory.
+	 */
+	hwcfg |= S3C24XX_DISRCC_INC_FIXED;
+
+	/*
+	 * Individual dma operations are requested by the slave,
+	 * so serve only single atomic operations (S3C24XX_DCON_SERV_SINGLE).
+	 */
+	txd->dcon |= S3C24XX_DCON_SERV_SINGLE;
+
+	if (direction == DMA_MEM_TO_DEV) {
+		txd->disrcc = S3C24XX_DISRCC_LOC_AHB |
+			      S3C24XX_DISRCC_INC_INCREMENT;
+		txd->didstc = hwcfg;
+		slave_addr = s3cchan->cfg.dst_addr;
+		txd->width = s3cchan->cfg.dst_addr_width;
+	} else if (direction == DMA_DEV_TO_MEM) {
+		txd->disrcc = hwcfg;
+		txd->didstc = S3C24XX_DIDSTC_LOC_AHB |
+			      S3C24XX_DIDSTC_INC_INCREMENT;
+		slave_addr = s3cchan->cfg.src_addr;
+		txd->width = s3cchan->cfg.src_addr_width;
+	} else {
+		s3c24xx_dma_free_txd(txd);
+		dev_err(&s3cdma->pdev->dev,
+			"direction %d unsupported\n", direction);
+		return NULL;
+	}
+
+	for_each_sg(sgl, sg, sg_len, tmp) {
+		dsg = kzalloc(sizeof(*dsg), GFP_NOWAIT);
+		if (!dsg) {
+			s3c24xx_dma_free_txd(txd);
+			return NULL;
+		}
+		list_add_tail(&dsg->node, &txd->dsg_list);
+
+		dsg->len = sg_dma_len(sg);
+		if (direction == DMA_MEM_TO_DEV) {
+			dsg->src_addr = sg_dma_address(sg);
+			dsg->dst_addr = slave_addr;
+		} else { /* DMA_DEV_TO_MEM */
+			dsg->src_addr = slave_addr;
+			dsg->dst_addr = sg_dma_address(sg);
+		}
+		break;
+	}
+
+	return vchan_tx_prep(&s3cchan->vc, &txd->vd, flags);
+}
+
+/*
+ * Slave transactions callback to the slave device to allow
+ * synchronization of slave DMA signals with the DMAC enable
+ */
+static void s3c24xx_dma_issue_pending(struct dma_chan *chan)
+{
+	struct s3c24xx_dma_chan *s3cchan = to_s3c24xx_dma_chan(chan);
+	unsigned long flags;
+
+	spin_lock_irqsave(&s3cchan->vc.lock, flags);
+	if (vchan_issue_pending(&s3cchan->vc)) {
+		if (!s3cchan->phy && s3cchan->state != S3C24XX_DMA_CHAN_WAITING)
+			s3c24xx_dma_phy_alloc_and_start(s3cchan);
+	}
+	spin_unlock_irqrestore(&s3cchan->vc.lock, flags);
+}
+
+/*
+ * Bringup and teardown
+ */
+
+/*
+ * Initialise the DMAC memcpy/slave channels.
+ * Make a local wrapper to hold required data
+ */
+static int s3c24xx_dma_init_virtual_channels(struct s3c24xx_dma_engine *s3cdma,
+		struct dma_device *dmadev, unsigned int channels, bool slave)
+{
+	struct s3c24xx_dma_chan *chan;
+	int i;
+
+	INIT_LIST_HEAD(&dmadev->channels);
+
+	/*
+	 * Register as many many memcpy as we have physical channels,
+	 * we won't always be able to use all but the code will have
+	 * to cope with that situation.
+	 */
+	for (i = 0; i < channels; i++) {
+		chan = devm_kzalloc(dmadev->dev, sizeof(*chan), GFP_KERNEL);
+		if (!chan) {
+			dev_err(dmadev->dev,
+				"%s no memory for channel\n", __func__);
+			return -ENOMEM;
+		}
+
+		chan->id = i;
+		chan->host = s3cdma;
+		chan->state = S3C24XX_DMA_CHAN_IDLE;
+
+		if (slave) {
+			chan->slave = true;
+			chan->name = kasprintf(GFP_KERNEL, "slave%d", i);
+			if (!chan->name)
+				return -ENOMEM;
+		} else {
+			chan->name = kasprintf(GFP_KERNEL, "memcpy%d", i);
+			if (!chan->name)
+				return -ENOMEM;
+		}
+		dev_dbg(dmadev->dev,
+			 "initialize virtual channel \"%s\"\n",
+			 chan->name);
+
+		chan->vc.desc_free = s3c24xx_dma_desc_free;
+		vchan_init(&chan->vc, dmadev);
+	}
+	dev_info(dmadev->dev, "initialized %d virtual %s channels\n",
+		 i, slave ? "slave" : "memcpy");
+	return i;
+}
+
+static void s3c24xx_dma_free_virtual_channels(struct dma_device *dmadev)
+{
+	struct s3c24xx_dma_chan *chan = NULL;
+	struct s3c24xx_dma_chan *next;
+
+	list_for_each_entry_safe(chan,
+				 next, &dmadev->channels, vc.chan.device_node)
+		list_del(&chan->vc.chan.device_node);
+}
+
+/* s3c2412 and s3c2413 have a 0x40 stride and dmareqsel mechanism */
+static struct soc_data soc_s3c2412 = {
+	.stride = 0x40,
+	.has_reqsel = true,
+	.has_clocks = true,
+};
+
+/* s3c2443 and following have a 0x100 stride and dmareqsel mechanism */
+static struct soc_data soc_s3c2443 = {
+	.stride = 0x100,
+	.has_reqsel = true,
+	.has_clocks = true,
+};
+
+static struct platform_device_id s3c24xx_dma_driver_ids[] = {
+	{
+		.name		= "s3c2412-dma",
+		.driver_data	= (kernel_ulong_t)&soc_s3c2412,
+	}, {
+		.name		= "s3c2443-dma",
+		.driver_data	= (kernel_ulong_t)&soc_s3c2443,
+	},
+	{ },
+};
+
+static struct soc_data *s3c24xx_dma_get_soc_data(struct platform_device *pdev)
+{
+	return (struct soc_data *)
+			 platform_get_device_id(pdev)->driver_data;
+}
+
+static int s3c24xx_dma_probe(struct platform_device *pdev)
+{
+	const struct s3c24xx_dma_platdata *pdata = dev_get_platdata(&pdev->dev);
+	struct s3c24xx_dma_engine *s3cdma;
+	struct soc_data *sdata;
+	struct resource *res;
+	int ret;
+	int i;
+
+	if (!pdata) {
+		dev_err(&pdev->dev, "platform data missing\n");
+		return -ENODEV;
+	}
+
+	/* Basic sanity check */
+	if (pdata->num_phy_channels > MAX_DMA_CHANNELS) {
+		dev_err(&pdev->dev, "to many dma channels %d, max %d\n",
+			pdata->num_phy_channels, MAX_DMA_CHANNELS);
+		return -EINVAL;
+	}
+
+	sdata = s3c24xx_dma_get_soc_data(pdev);
+	if (!sdata)
+		return -EINVAL;
+
+	s3cdma = devm_kzalloc(&pdev->dev, sizeof(*s3cdma), GFP_KERNEL);
+	if (!s3cdma)
+		return -ENOMEM;
+
+	s3cdma->pdev = pdev;
+	s3cdma->pdata = pdata;
+	s3cdma->sdata = sdata;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	s3cdma->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(s3cdma->base))
+		return PTR_ERR(s3cdma->base);
+
+	s3cdma->phy_chans = devm_kzalloc(&pdev->dev,
+					      sizeof(struct s3c24xx_dma_phy) *
+							pdata->num_phy_channels,
+					      GFP_KERNEL);
+	if (!s3cdma->phy_chans)
+		return -ENOMEM;
+
+	/* aquire irqs and clocks for all physical channels */
+	for (i = 0; i < pdata->num_phy_channels; i++) {
+		struct s3c24xx_dma_phy *phy = &s3cdma->phy_chans[i];
+		char clk_name[6];
+
+		phy->id = i;
+		phy->base = s3cdma->base + (i * sdata->stride);
+		phy->host = s3cdma;
+
+		phy->irq = platform_get_irq(pdev, i);
+		if (phy->irq < 0) {
+			dev_err(&pdev->dev, "failed to get irq %d, err %d\n",
+				i, phy->irq);
+			continue;
+		}
+
+		ret = devm_request_irq(&pdev->dev, phy->irq, s3c24xx_dma_irq,
+				       0, pdev->name, phy);
+		if (ret) {
+			dev_err(&pdev->dev, "Unable to request irq for channel %d, error %d\n",
+				i, ret);
+			continue;
+		}
+
+		if (sdata->has_clocks) {
+			sprintf(clk_name, "dma.%d", i);
+			phy->clk = devm_clk_get(&pdev->dev, clk_name);
+			if (IS_ERR(phy->clk) && sdata->has_clocks) {
+				dev_err(&pdev->dev, "unable to aquire clock for channel %d, error %lu",
+					i, PTR_ERR(phy->clk));
+				continue;
+			}
+
+			ret = clk_prepare(phy->clk);
+			if (ret) {
+				dev_err(&pdev->dev, "clock for phy %d failed, error %d\n",
+					i, ret);
+				continue;
+			}
+		}
+
+		spin_lock_init(&phy->lock);
+		phy->valid = true;
+
+		dev_dbg(&pdev->dev, "physical channel %d is %s\n",
+			i, s3c24xx_dma_phy_busy(phy) ? "BUSY" : "FREE");
+	}
+
+	/* Initialize memcpy engine */
+	dma_cap_set(DMA_MEMCPY, s3cdma->memcpy.cap_mask);
+	dma_cap_set(DMA_PRIVATE, s3cdma->memcpy.cap_mask);
+	s3cdma->memcpy.dev = &pdev->dev;
+	s3cdma->memcpy.device_alloc_chan_resources =
+					s3c24xx_dma_alloc_chan_resources;
+	s3cdma->memcpy.device_free_chan_resources =
+					s3c24xx_dma_free_chan_resources;
+	s3cdma->memcpy.device_prep_dma_memcpy = s3c24xx_dma_prep_memcpy;
+	s3cdma->memcpy.device_tx_status = s3c24xx_dma_tx_status;
+	s3cdma->memcpy.device_issue_pending = s3c24xx_dma_issue_pending;
+	s3cdma->memcpy.device_control = s3c24xx_dma_control;
+
+	/* Initialize slave engine for SoC internal dedicated peripherals */
+	dma_cap_set(DMA_SLAVE, s3cdma->slave.cap_mask);
+	dma_cap_set(DMA_PRIVATE, s3cdma->slave.cap_mask);
+	s3cdma->slave.dev = &pdev->dev;
+	s3cdma->slave.device_alloc_chan_resources =
+					s3c24xx_dma_alloc_chan_resources;
+	s3cdma->slave.device_free_chan_resources =
+					s3c24xx_dma_free_chan_resources;
+	s3cdma->slave.device_tx_status = s3c24xx_dma_tx_status;
+	s3cdma->slave.device_issue_pending = s3c24xx_dma_issue_pending;
+	s3cdma->slave.device_prep_slave_sg = s3c24xx_dma_prep_slave_sg;
+	s3cdma->slave.device_control = s3c24xx_dma_control;
+
+	/* Register as many memcpy channels as there are physical channels */
+	ret = s3c24xx_dma_init_virtual_channels(s3cdma, &s3cdma->memcpy,
+						pdata->num_phy_channels, false);
+	if (ret <= 0) {
+		dev_warn(&pdev->dev,
+			 "%s failed to enumerate memcpy channels - %d\n",
+			 __func__, ret);
+		goto err_memcpy;
+	}
+
+	/* Register slave channels */
+	ret = s3c24xx_dma_init_virtual_channels(s3cdma, &s3cdma->slave,
+				pdata->num_channels, true);
+	if (ret <= 0) {
+		dev_warn(&pdev->dev,
+			"%s failed to enumerate slave channels - %d\n",
+				__func__, ret);
+		goto err_slave;
+	}
+
+	ret = dma_async_device_register(&s3cdma->memcpy);
+	if (ret) {
+		dev_warn(&pdev->dev,
+			"%s failed to register memcpy as an async device - %d\n",
+			__func__, ret);
+		goto err_memcpy_reg;
+	}
+
+	ret = dma_async_device_register(&s3cdma->slave);
+	if (ret) {
+		dev_warn(&pdev->dev,
+			"%s failed to register slave as an async device - %d\n",
+			__func__, ret);
+		goto err_slave_reg;
+	}
+
+	platform_set_drvdata(pdev, s3cdma);
+	dev_info(&pdev->dev, "Loaded dma driver with %d physical channels\n",
+		 pdata->num_phy_channels);
+
+	return 0;
+
+err_slave_reg:
+	dma_async_device_unregister(&s3cdma->memcpy);
+err_memcpy_reg:
+	s3c24xx_dma_free_virtual_channels(&s3cdma->slave);
+err_slave:
+	s3c24xx_dma_free_virtual_channels(&s3cdma->memcpy);
+err_memcpy:
+	if (sdata->has_clocks)
+		for (i = 0; i < pdata->num_phy_channels; i++) {
+			struct s3c24xx_dma_phy *phy = &s3cdma->phy_chans[i];
+			if (phy->valid)
+				clk_unprepare(phy->clk);
+		}
+
+	return ret;
+}
+
+static int s3c24xx_dma_remove(struct platform_device *pdev)
+{
+	const struct s3c24xx_dma_platdata *pdata = dev_get_platdata(&pdev->dev);
+	struct s3c24xx_dma_engine *s3cdma = platform_get_drvdata(pdev);
+	struct soc_data *sdata = s3c24xx_dma_get_soc_data(pdev);
+	int i;
+
+	dma_async_device_unregister(&s3cdma->slave);
+	dma_async_device_unregister(&s3cdma->memcpy);
+
+	s3c24xx_dma_free_virtual_channels(&s3cdma->slave);
+	s3c24xx_dma_free_virtual_channels(&s3cdma->memcpy);
+
+	if (sdata->has_clocks)
+		for (i = 0; i < pdata->num_phy_channels; i++) {
+			struct s3c24xx_dma_phy *phy = &s3cdma->phy_chans[i];
+			if (phy->valid)
+				clk_unprepare(phy->clk);
+		}
+
+	return 0;
+}
+
+static struct platform_driver s3c24xx_dma_driver = {
+	.driver		= {
+		.name	= "s3c24xx-dma",
+		.owner	= THIS_MODULE,
+	},
+	.id_table	= s3c24xx_dma_driver_ids,
+	.probe		= s3c24xx_dma_probe,
+	.remove		= s3c24xx_dma_remove,
+};
+
+module_platform_driver(s3c24xx_dma_driver);
+
+bool s3c24xx_dma_filter(struct dma_chan *chan, void *param)
+{
+	struct s3c24xx_dma_chan *s3cchan;
+
+	if (chan->device->dev->driver != &s3c24xx_dma_driver.driver)
+		return false;
+
+	s3cchan = to_s3c24xx_dma_chan(chan);
+
+	return s3cchan->id == (int)param;
+}
+EXPORT_SYMBOL(s3c24xx_dma_filter);
+
+MODULE_DESCRIPTION("S3C24XX DMA Driver");
+MODULE_AUTHOR("Heiko Stuebner");
+MODULE_LICENSE("GPL v2");

include/linux/platform_data/dma-s3c24xx.h

+/*
+ * S3C24XX DMA handling
+ *
+ * Copyright (c) 2013 Heiko Stuebner <heiko@sntech.de>
+ *
+ * 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.
+ */
+
+enum s3c24xx_dma_bus {
+	S3C24XX_DMA_APB,
+	S3C24XX_DMA_AHB,
+};
+
+/**
+ * @bus: on which bus does the peripheral reside - AHB or APB.
+ * @handshake: is a handshake with the peripheral necessary
+ * @chansel: channel selection information, depending on variant; reqsel for
+ *	     s3c2443 and later and channel-selection map for earlier SoCs
+ *	     see CHANSEL doc in s3c2443-dma.c
+ */
+struct s3c24xx_dma_channel {
+	enum s3c24xx_dma_bus bus;
+	bool handshake;
+	u16 chansel;
+};
+
+/**
+ * struct s3c24xx_dma_platdata - platform specific settings
+ * @num_phy_channels: number of physical channels
+ * @channels: array of virtual channel descriptions
+ * @num_channels: number of virtual channels
+ */
+struct s3c24xx_dma_platdata {
+	int num_phy_channels;
+	struct s3c24xx_dma_channel *channels;
+	int num_channels;
+};
+
+struct dma_chan;
+bool s3c24xx_dma_filter(struct dma_chan *chan, void *param);