dma: Add MPC512x DMA driver

Adds initial version of MPC512x DMA driver.
Only memory to memory transfers are currenly supported.
Signed-off-by: Piotr Ziecik <kosmo@semihalf.com>
Signed-off-by: Wolfgang Denk <wd@denx.de>
Signed-off-by: Anatolij Gustschin <agust@denx.de>
Cc: John Rigby <jcrigby@gmail.com>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/dma/Kconfig

@@ -85,6 +85,13 @@ config FSL_DMA
 	  The Elo is the DMA controller on some 82xx and 83xx parts, and the
 	  Elo Plus is the DMA controller on 85xx and 86xx parts.
 
+config MPC512X_DMA
+	tristate "Freescale MPC512x built-in DMA engine support"
+	depends on PPC_MPC512x
+	select DMA_ENGINE
+	---help---
+	  Enable support for the Freescale MPC512x built-in DMA engine.
+
 config MV_XOR
 	bool "Marvell XOR engine support"
 	depends on PLAT_ORION

drivers/dma/Makefile

@@ -11,6 +11,7 @@ obj-$(CONFIG_DMATEST) += dmatest.o
 obj-$(CONFIG_INTEL_IOATDMA) += ioat/
 obj-$(CONFIG_INTEL_IOP_ADMA) += iop-adma.o
 obj-$(CONFIG_FSL_DMA) += fsldma.o
+obj-$(CONFIG_MPC512X_DMA) += mpc512x_dma.o
 obj-$(CONFIG_MV_XOR) += mv_xor.o
 obj-$(CONFIG_DW_DMAC) += dw_dmac.o
 obj-$(CONFIG_AT_HDMAC) += at_hdmac.o

drivers/dma/mpc512x_dma.c

+/*
+ * Copyright (C) Freescale Semicondutor, Inc. 2007, 2008.
+ * Copyright (C) Semihalf 2009
+ *
+ * Written by Piotr Ziecik <kosmo@semihalf.com>. Hardware description
+ * (defines, structures and comments) was taken from MPC5121 DMA driver
+ * written by Hongjun Chen <hong-jun.chen@freescale.com>.
+ *
+ * Approved as OSADL project by a majority of OSADL members and funded
+ * by OSADL membership fees in 2009;  for details see www.osadl.org.
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc., 59
+ * Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+ *
+ * The full GNU General Public License is included in this distribution in the
+ * file called COPYING.
+ */
+
+/*
+ * This is initial version of MPC5121 DMA driver. Only memory to memory
+ * transfers are supported (tested using dmatest module).
+ */
+
+#include <linux/module.h>
+#include <linux/dmaengine.h>
+#include <linux/dma-mapping.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/of_device.h>
+#include <linux/of_platform.h>
+
+#include <linux/random.h>
+
+/* Number of DMA Transfer descriptors allocated per channel */
+#define MPC_DMA_DESCRIPTORS	64
+
+/* Macro definitions */
+#define MPC_DMA_CHANNELS	64
+#define MPC_DMA_TCD_OFFSET	0x1000
+
+/* Arbitration mode of group and channel */
+#define MPC_DMA_DMACR_EDCG	(1 << 31)
+#define MPC_DMA_DMACR_ERGA	(1 << 3)
+#define MPC_DMA_DMACR_ERCA	(1 << 2)
+
+/* Error codes */
+#define MPC_DMA_DMAES_VLD	(1 << 31)
+#define MPC_DMA_DMAES_GPE	(1 << 15)
+#define MPC_DMA_DMAES_CPE	(1 << 14)
+#define MPC_DMA_DMAES_ERRCHN(err) \
+				(((err) >> 8) & 0x3f)
+#define MPC_DMA_DMAES_SAE	(1 << 7)
+#define MPC_DMA_DMAES_SOE	(1 << 6)
+#define MPC_DMA_DMAES_DAE	(1 << 5)
+#define MPC_DMA_DMAES_DOE	(1 << 4)
+#define MPC_DMA_DMAES_NCE	(1 << 3)
+#define MPC_DMA_DMAES_SGE	(1 << 2)
+#define MPC_DMA_DMAES_SBE	(1 << 1)
+#define MPC_DMA_DMAES_DBE	(1 << 0)
+
+#define MPC_DMA_TSIZE_1		0x00
+#define MPC_DMA_TSIZE_2		0x01
+#define MPC_DMA_TSIZE_4		0x02
+#define MPC_DMA_TSIZE_16	0x04
+#define MPC_DMA_TSIZE_32	0x05
+
+/* MPC5121 DMA engine registers */
+struct __attribute__ ((__packed__)) mpc_dma_regs {
+	/* 0x00 */
+	u32 dmacr;		/* DMA control register */
+	u32 dmaes;		/* DMA error status */
+	/* 0x08 */
+	u32 dmaerqh;		/* DMA enable request high(channels 63~32) */
+	u32 dmaerql;		/* DMA enable request low(channels 31~0) */
+	u32 dmaeeih;		/* DMA enable error interrupt high(ch63~32) */
+	u32 dmaeeil;		/* DMA enable error interrupt low(ch31~0) */
+	/* 0x18 */
+	u8 dmaserq;		/* DMA set enable request */
+	u8 dmacerq;		/* DMA clear enable request */
+	u8 dmaseei;		/* DMA set enable error interrupt */
+	u8 dmaceei;		/* DMA clear enable error interrupt */
+	/* 0x1c */
+	u8 dmacint;		/* DMA clear interrupt request */
+	u8 dmacerr;		/* DMA clear error */
+	u8 dmassrt;		/* DMA set start bit */
+	u8 dmacdne;		/* DMA clear DONE status bit */
+	/* 0x20 */
+	u32 dmainth;		/* DMA interrupt request high(ch63~32) */
+	u32 dmaintl;		/* DMA interrupt request low(ch31~0) */
+	u32 dmaerrh;		/* DMA error high(ch63~32) */
+	u32 dmaerrl;		/* DMA error low(ch31~0) */
+	/* 0x30 */
+	u32 dmahrsh;		/* DMA hw request status high(ch63~32) */
+	u32 dmahrsl;		/* DMA hardware request status low(ch31~0) */
+	u32 dmaihsa;		/* DMA interrupt high select AXE(ch63~32) */
+	u32 dmailsa;		/* DMA interrupt low select AXE(ch31~0) */
+	/* 0x40 ~ 0xff */
+	u32 reserve0[48];	/* Reserved */
+	/* 0x100 */
+	u8 dchpri[MPC_DMA_CHANNELS];
+	/* DMA channels(0~63) priority */
+};
+
+struct __attribute__ ((__packed__)) mpc_dma_tcd {
+	/* 0x00 */
+	u32 saddr;		/* Source address */
+
+	u32 smod:5;		/* Source address modulo */
+	u32 ssize:3;		/* Source data transfer size */
+	u32 dmod:5;		/* Destination address modulo */
+	u32 dsize:3;		/* Destination data transfer size */
+	u32 soff:16;		/* Signed source address offset */
+
+	/* 0x08 */
+	u32 nbytes;		/* Inner "minor" byte count */
+	u32 slast;		/* Last source address adjustment */
+	u32 daddr;		/* Destination address */
+
+	/* 0x14 */
+	u32 citer_elink:1;	/* Enable channel-to-channel linking on
+				 * minor loop complete
+				 */
+	u32 citer_linkch:6;	/* Link channel for minor loop complete */
+	u32 citer:9;		/* Current "major" iteration count */
+	u32 doff:16;		/* Signed destination address offset */
+
+	/* 0x18 */
+	u32 dlast_sga;		/* Last Destination address adjustment/scatter
+				 * gather address
+				 */
+
+	/* 0x1c */
+	u32 biter_elink:1;	/* Enable channel-to-channel linking on major
+				 * loop complete
+				 */
+	u32 biter_linkch:6;
+	u32 biter:9;		/* Beginning "major" iteration count */
+	u32 bwc:2;		/* Bandwidth control */
+	u32 major_linkch:6;	/* Link channel number */
+	u32 done:1;		/* Channel done */
+	u32 active:1;		/* Channel active */
+	u32 major_elink:1;	/* Enable channel-to-channel linking on major
+				 * loop complete
+				 */
+	u32 e_sg:1;		/* Enable scatter/gather processing */
+	u32 d_req:1;		/* Disable request */
+	u32 int_half:1;		/* Enable an interrupt when major counter is
+				 * half complete
+				 */
+	u32 int_maj:1;		/* Enable an interrupt when major iteration
+				 * count completes
+				 */
+	u32 start:1;		/* Channel start */
+};
+
+struct mpc_dma_desc {
+	struct dma_async_tx_descriptor	desc;
+	struct mpc_dma_tcd		*tcd;
+	dma_addr_t			tcd_paddr;
+	int				error;
+	struct list_head		node;
+};
+
+struct mpc_dma_chan {
+	struct dma_chan			chan;
+	struct list_head		free;
+	struct list_head		prepared;
+	struct list_head		queued;
+	struct list_head		active;
+	struct list_head		completed;
+	struct mpc_dma_tcd		*tcd;
+	dma_addr_t			tcd_paddr;
+	dma_cookie_t			completed_cookie;
+
+	/* Lock for this structure */
+	spinlock_t			lock;
+};
+
+struct mpc_dma {
+	struct dma_device		dma;
+	struct tasklet_struct		tasklet;
+	struct mpc_dma_chan		channels[MPC_DMA_CHANNELS];
+	struct mpc_dma_regs __iomem	*regs;
+	struct mpc_dma_tcd __iomem	*tcd;
+	int				irq;
+	uint				error_status;
+
+	/* Lock for error_status field in this structure */
+	spinlock_t			error_status_lock;
+};
+
+#define DRV_NAME	"mpc512x_dma"
+
+/* Convert struct dma_chan to struct mpc_dma_chan */
+static inline struct mpc_dma_chan *dma_chan_to_mpc_dma_chan(struct dma_chan *c)
+{
+	return container_of(c, struct mpc_dma_chan, chan);
+}
+
+/* Convert struct dma_chan to struct mpc_dma */
+static inline struct mpc_dma *dma_chan_to_mpc_dma(struct dma_chan *c)
+{
+	struct mpc_dma_chan *mchan = dma_chan_to_mpc_dma_chan(c);
+	return container_of(mchan, struct mpc_dma, channels[c->chan_id]);
+}
+
+/*
+ * Execute all queued DMA descriptors.
+ *
+ * Following requirements must be met while calling mpc_dma_execute():
+ * 	a) mchan->lock is acquired,
+ * 	b) mchan->active list is empty,
+ * 	c) mchan->queued list contains at least one entry.
+ */
+static void mpc_dma_execute(struct mpc_dma_chan *mchan)
+{
+	struct mpc_dma *mdma = dma_chan_to_mpc_dma(&mchan->chan);
+	struct mpc_dma_desc *first = NULL;
+	struct mpc_dma_desc *prev = NULL;
+	struct mpc_dma_desc *mdesc;
+	int cid = mchan->chan.chan_id;
+
+	/* Move all queued descriptors to active list */
+	list_splice_tail_init(&mchan->queued, &mchan->active);
+
+	/* Chain descriptors into one transaction */
+	list_for_each_entry(mdesc, &mchan->active, node) {
+		if (!first)
+			first = mdesc;
+
+		if (!prev) {
+			prev = mdesc;
+			continue;
+		}
+
+		prev->tcd->dlast_sga = mdesc->tcd_paddr;
+		prev->tcd->e_sg = 1;
+		mdesc->tcd->start = 1;
+
+		prev = mdesc;
+	}
+
+	prev->tcd->start = 0;
+	prev->tcd->int_maj = 1;
+
+	/* Send first descriptor in chain into hardware */
+	memcpy_toio(&mdma->tcd[cid], first->tcd, sizeof(struct mpc_dma_tcd));
+	out_8(&mdma->regs->dmassrt, cid);
+}
+
+/* Handle interrupt on one half of DMA controller (32 channels) */
+static void mpc_dma_irq_process(struct mpc_dma *mdma, u32 is, u32 es, int off)
+{
+	struct mpc_dma_chan *mchan;
+	struct mpc_dma_desc *mdesc;
+	u32 status = is | es;
+	int ch;
+
+	while ((ch = fls(status) - 1) >= 0) {
+		status &= ~(1 << ch);
+		mchan = &mdma->channels[ch + off];
+
+		spin_lock(&mchan->lock);
+
+		/* Check error status */
+		if (es & (1 << ch))
+			list_for_each_entry(mdesc, &mchan->active, node)
+				mdesc->error = -EIO;
+
+		/* Execute queued descriptors */
+		list_splice_tail_init(&mchan->active, &mchan->completed);
+		if (!list_empty(&mchan->queued))
+			mpc_dma_execute(mchan);
+
+		spin_unlock(&mchan->lock);
+	}
+}
+
+/* Interrupt handler */
+static irqreturn_t mpc_dma_irq(int irq, void *data)
+{
+	struct mpc_dma *mdma = data;
+	uint es;
+
+	/* Save error status register */
+	es = in_be32(&mdma->regs->dmaes);
+	spin_lock(&mdma->error_status_lock);
+	if ((es & MPC_DMA_DMAES_VLD) && mdma->error_status == 0)
+		mdma->error_status = es;
+	spin_unlock(&mdma->error_status_lock);
+
+	/* Handle interrupt on each channel */
+	mpc_dma_irq_process(mdma, in_be32(&mdma->regs->dmainth),
+					in_be32(&mdma->regs->dmaerrh), 32);
+	mpc_dma_irq_process(mdma, in_be32(&mdma->regs->dmaintl),
+					in_be32(&mdma->regs->dmaerrl), 0);
+
+	/* Ack interrupt on all channels */
+	out_be32(&mdma->regs->dmainth, 0xFFFFFFFF);
+	out_be32(&mdma->regs->dmaintl, 0xFFFFFFFF);
+	out_be32(&mdma->regs->dmaerrh, 0xFFFFFFFF);
+	out_be32(&mdma->regs->dmaerrl, 0xFFFFFFFF);
+
+	/* Schedule tasklet */
+	tasklet_schedule(&mdma->tasklet);
+
+	return IRQ_HANDLED;
+}
+
+/* DMA Tasklet */
+static void mpc_dma_tasklet(unsigned long data)
+{
+	struct mpc_dma *mdma = (void *)data;
+	dma_cookie_t last_cookie = 0;
+	struct mpc_dma_chan *mchan;
+	struct mpc_dma_desc *mdesc;
+	struct dma_async_tx_descriptor *desc;
+	unsigned long flags;
+	LIST_HEAD(list);
+	uint es;
+	int i;
+
+	spin_lock_irqsave(&mdma->error_status_lock, flags);
+	es = mdma->error_status;
+	mdma->error_status = 0;
+	spin_unlock_irqrestore(&mdma->error_status_lock, flags);
+
+	/* Print nice error report */
+	if (es) {
+		dev_err(mdma->dma.dev,
+			"Hardware reported following error(s) on channel %u:\n",
+						      MPC_DMA_DMAES_ERRCHN(es));
+
+		if (es & MPC_DMA_DMAES_GPE)
+			dev_err(mdma->dma.dev, "- Group Priority Error\n");
+		if (es & MPC_DMA_DMAES_CPE)
+			dev_err(mdma->dma.dev, "- Channel Priority Error\n");
+		if (es & MPC_DMA_DMAES_SAE)
+			dev_err(mdma->dma.dev, "- Source Address Error\n");
+		if (es & MPC_DMA_DMAES_SOE)
+			dev_err(mdma->dma.dev, "- Source Offset"
+						" Configuration Error\n");
+		if (es & MPC_DMA_DMAES_DAE)
+			dev_err(mdma->dma.dev, "- Destination Address"
+								" Error\n");
+		if (es & MPC_DMA_DMAES_DOE)
+			dev_err(mdma->dma.dev, "- Destination Offset"
+						" Configuration Error\n");
+		if (es & MPC_DMA_DMAES_NCE)
+			dev_err(mdma->dma.dev, "- NBytes/Citter"
+						" Configuration Error\n");
+		if (es & MPC_DMA_DMAES_SGE)
+			dev_err(mdma->dma.dev, "- Scatter/Gather"
+						" Configuration Error\n");
+		if (es & MPC_DMA_DMAES_SBE)
+			dev_err(mdma->dma.dev, "- Source Bus Error\n");
+		if (es & MPC_DMA_DMAES_DBE)
+			dev_err(mdma->dma.dev, "- Destination Bus Error\n");
+	}
+
+	for (i = 0; i < mdma->dma.chancnt; i++) {
+		mchan = &mdma->channels[i];
+
+		/* Get all completed descriptors */
+		spin_lock_irqsave(&mchan->lock, flags);
+		if (!list_empty(&mchan->completed))
+			list_splice_tail_init(&mchan->completed, &list);
+		spin_unlock_irqrestore(&mchan->lock, flags);
+
+		if (list_empty(&list))
+			continue;
+
+		/* Execute callbacks and run dependencies */
+		list_for_each_entry(mdesc, &list, node) {
+			desc = &mdesc->desc;
+
+			if (desc->callback)
+				desc->callback(desc->callback_param);
+
+			last_cookie = desc->cookie;
+			dma_run_dependencies(desc);
+		}
+
+		/* Free descriptors */
+		spin_lock_irqsave(&mchan->lock, flags);
+		list_splice_tail_init(&list, &mchan->free);
+		mchan->completed_cookie = last_cookie;
+		spin_unlock_irqrestore(&mchan->lock, flags);
+	}
+}
+
+/* Submit descriptor to hardware */
+static dma_cookie_t mpc_dma_tx_submit(struct dma_async_tx_descriptor *txd)
+{
+	struct mpc_dma_chan *mchan = dma_chan_to_mpc_dma_chan(txd->chan);
+	struct mpc_dma_desc *mdesc;
+	unsigned long flags;
+	dma_cookie_t cookie;
+
+	mdesc = container_of(txd, struct mpc_dma_desc, desc);
+
+	spin_lock_irqsave(&mchan->lock, flags);
+
+	/* Move descriptor to queue */
+	list_move_tail(&mdesc->node, &mchan->queued);
+
+	/* If channel is idle, execute all queued descriptors */
+	if (list_empty(&mchan->active))
+		mpc_dma_execute(mchan);
+
+	/* Update cookie */
+	cookie = mchan->chan.cookie + 1;
+	if (cookie <= 0)
+		cookie = 1;
+
+	mchan->chan.cookie = cookie;
+	mdesc->desc.cookie = cookie;
+
+	spin_unlock_irqrestore(&mchan->lock, flags);
+
+	return cookie;
+}
+
+/* Alloc channel resources */
+static int mpc_dma_alloc_chan_resources(struct dma_chan *chan)
+{
+	struct mpc_dma *mdma = dma_chan_to_mpc_dma(chan);
+	struct mpc_dma_chan *mchan = dma_chan_to_mpc_dma_chan(chan);
+	struct mpc_dma_desc *mdesc;
+	struct mpc_dma_tcd *tcd;
+	dma_addr_t tcd_paddr;
+	unsigned long flags;
+	LIST_HEAD(descs);
+	int i;
+
+	/* Alloc DMA memory for Transfer Control Descriptors */
+	tcd = dma_alloc_coherent(mdma->dma.dev,
+			MPC_DMA_DESCRIPTORS * sizeof(struct mpc_dma_tcd),
+							&tcd_paddr, GFP_KERNEL);
+	if (!tcd)
+		return -ENOMEM;
+
+	/* Alloc descriptors for this channel */
+	for (i = 0; i < MPC_DMA_DESCRIPTORS; i++) {
+		mdesc = kzalloc(sizeof(struct mpc_dma_desc), GFP_KERNEL);
+		if (!mdesc) {
+			dev_notice(mdma->dma.dev, "Memory allocation error. "
+					"Allocated only %u descriptors\n", i);
+			break;
+		}
+
+		dma_async_tx_descriptor_init(&mdesc->desc, chan);
+		mdesc->desc.flags = DMA_CTRL_ACK;
+		mdesc->desc.tx_submit = mpc_dma_tx_submit;
+
+		mdesc->tcd = &tcd[i];
+		mdesc->tcd_paddr = tcd_paddr + (i * sizeof(struct mpc_dma_tcd));
+
+		list_add_tail(&mdesc->node, &descs);
+	}
+
+	/* Return error only if no descriptors were allocated */
+	if (i == 0) {
+		dma_free_coherent(mdma->dma.dev,
+			MPC_DMA_DESCRIPTORS * sizeof(struct mpc_dma_tcd),
+								tcd, tcd_paddr);
+		return -ENOMEM;
+	}
+
+	spin_lock_irqsave(&mchan->lock, flags);
+	mchan->tcd = tcd;
+	mchan->tcd_paddr = tcd_paddr;
+	list_splice_tail_init(&descs, &mchan->free);
+	spin_unlock_irqrestore(&mchan->lock, flags);
+
+	/* Enable Error Interrupt */
+	out_8(&mdma->regs->dmaseei, chan->chan_id);
+
+	return 0;
+}
+
+/* Free channel resources */
+static void mpc_dma_free_chan_resources(struct dma_chan *chan)
+{
+	struct mpc_dma *mdma = dma_chan_to_mpc_dma(chan);
+	struct mpc_dma_chan *mchan = dma_chan_to_mpc_dma_chan(chan);
+	struct mpc_dma_desc *mdesc, *tmp;
+	struct mpc_dma_tcd *tcd;
+	dma_addr_t tcd_paddr;
+	unsigned long flags;
+	LIST_HEAD(descs);
+
+	spin_lock_irqsave(&mchan->lock, flags);
+
+	/* Channel must be idle */
+	BUG_ON(!list_empty(&mchan->prepared));
+	BUG_ON(!list_empty(&mchan->queued));
+	BUG_ON(!list_empty(&mchan->active));
+	BUG_ON(!list_empty(&mchan->completed));
+
+	/* Move data */
+	list_splice_tail_init(&mchan->free, &descs);
+	tcd = mchan->tcd;
+	tcd_paddr = mchan->tcd_paddr;
+
+	spin_unlock_irqrestore(&mchan->lock, flags);
+
+	/* Free DMA memory used by descriptors */
+	dma_free_coherent(mdma->dma.dev,
+			MPC_DMA_DESCRIPTORS * sizeof(struct mpc_dma_tcd),
+								tcd, tcd_paddr);
+
+	/* Free descriptors */
+	list_for_each_entry_safe(mdesc, tmp, &descs, node)
+		kfree(mdesc);
+
+	/* Disable Error Interrupt */
+	out_8(&mdma->regs->dmaceei, chan->chan_id);
+}
+
+/* Send all pending descriptor to hardware */
+static void mpc_dma_issue_pending(struct dma_chan *chan)
+{
+	/*
+	 * We are posting descriptors to the hardware as soon as
+	 * they are ready, so this function does nothing.
+	 */
+}
+
+/* Check request completion status */
+static enum dma_status
+mpc_dma_is_tx_complete(struct dma_chan *chan, dma_cookie_t cookie,
+					dma_cookie_t *done, dma_cookie_t *used)
+{
+	struct mpc_dma_chan *mchan = dma_chan_to_mpc_dma_chan(chan);
+	unsigned long flags;
+	dma_cookie_t last_used;
+	dma_cookie_t last_complete;
+
+	spin_lock_irqsave(&mchan->lock, flags);
+	last_used = mchan->chan.cookie;
+	last_complete = mchan->completed_cookie;
+	spin_unlock_irqrestore(&mchan->lock, flags);
+
+	if (done)
+		*done = last_complete;
+
+	if (used)
+		*used = last_used;
+
+	return dma_async_is_complete(cookie, last_complete, last_used);
+}
+
+/* Prepare descriptor for memory to memory copy */
+static struct dma_async_tx_descriptor *
+mpc_dma_prep_memcpy(struct dma_chan *chan, dma_addr_t dst, dma_addr_t src,
+					size_t len, unsigned long flags)
+{
+	struct mpc_dma_chan *mchan = dma_chan_to_mpc_dma_chan(chan);
+	struct mpc_dma_desc *mdesc = NULL;
+	struct mpc_dma_tcd *tcd;
+	unsigned long iflags;
+
+	/* Get free descriptor */
+	spin_lock_irqsave(&mchan->lock, iflags);
+	if (!list_empty(&mchan->free)) {
+		mdesc = list_first_entry(&mchan->free, struct mpc_dma_desc,
+									node);
+		list_del(&mdesc->node);
+	}
+	spin_unlock_irqrestore(&mchan->lock, iflags);
+
+	if (!mdesc)
+		return NULL;
+
+	mdesc->error = 0;
+	tcd = mdesc->tcd;
+
+	/* Prepare Transfer Control Descriptor for this transaction */
+	memset(tcd, 0, sizeof(struct mpc_dma_tcd));
+
+	if (IS_ALIGNED(src | dst | len, 32)) {
+		tcd->ssize = MPC_DMA_TSIZE_32;
+		tcd->dsize = MPC_DMA_TSIZE_32;
+		tcd->soff = 32;
+		tcd->doff = 32;
+	} else if (IS_ALIGNED(src | dst | len, 16)) {
+		tcd->ssize = MPC_DMA_TSIZE_16;
+		tcd->dsize = MPC_DMA_TSIZE_16;
+		tcd->soff = 16;
+		tcd->doff = 16;
+	} else if (IS_ALIGNED(src | dst | len, 4)) {
+		tcd->ssize = MPC_DMA_TSIZE_4;
+		tcd->dsize = MPC_DMA_TSIZE_4;
+		tcd->soff = 4;
+		tcd->doff = 4;
+	} else if (IS_ALIGNED(src | dst | len, 2)) {
+		tcd->ssize = MPC_DMA_TSIZE_2;
+		tcd->dsize = MPC_DMA_TSIZE_2;
+		tcd->soff = 2;
+		tcd->doff = 2;
+	} else {
+		tcd->ssize = MPC_DMA_TSIZE_1;
+		tcd->dsize = MPC_DMA_TSIZE_1;
+		tcd->soff = 1;
+		tcd->doff = 1;
+	}
+
+	tcd->saddr = src;
+	tcd->daddr = dst;
+	tcd->nbytes = len;
+	tcd->biter = 1;
+	tcd->citer = 1;
+
+	/* Place descriptor in prepared list */
+	spin_lock_irqsave(&mchan->lock, iflags);
+	list_add_tail(&mdesc->node, &mchan->prepared);
+	spin_unlock_irqrestore(&mchan->lock, iflags);
+
+	return &mdesc->desc;
+}
+
+static int __devinit mpc_dma_probe(struct of_device *op,
+					const struct of_device_id *match)
+{
+	struct device_node *dn = op->node;
+	struct device *dev = &op->dev;
+	struct dma_device *dma;
+	struct mpc_dma *mdma;
+	struct mpc_dma_chan *mchan;
+	struct resource res;
+	ulong regs_start, regs_size;
+	int retval, i;
+
+	mdma = devm_kzalloc(dev, sizeof(struct mpc_dma), GFP_KERNEL);
+	if (!mdma) {
+		dev_err(dev, "Memory exhausted!\n");
+		return -ENOMEM;
+	}
+
+	mdma->irq = irq_of_parse_and_map(dn, 0);
+	if (mdma->irq == NO_IRQ) {
+		dev_err(dev, "Error mapping IRQ!\n");
+		return -EINVAL;
+	}
+
+	retval = of_address_to_resource(dn, 0, &res);
+	if (retval) {
+		dev_err(dev, "Error parsing memory region!\n");
+		return retval;
+	}
+
+	regs_start = res.start;
+	regs_size = res.end - res.start + 1;
+
+	if (!devm_request_mem_region(dev, regs_start, regs_size, DRV_NAME)) {
+		dev_err(dev, "Error requesting memory region!\n");
+		return -EBUSY;
+	}
+
+	mdma->regs = devm_ioremap(dev, regs_start, regs_size);
+	if (!mdma->regs) {
+		dev_err(dev, "Error mapping memory region!\n");
+		return -ENOMEM;
+	}
+
+	mdma->tcd = (struct mpc_dma_tcd *)((u8 *)(mdma->regs)
+							+ MPC_DMA_TCD_OFFSET);
+
+	retval = devm_request_irq(dev, mdma->irq, &mpc_dma_irq, 0, DRV_NAME,
+									mdma);
+	if (retval) {
+		dev_err(dev, "Error requesting IRQ!\n");
+		return -EINVAL;
+	}
+
+	spin_lock_init(&mdma->error_status_lock);
+
+	dma = &mdma->dma;
+	dma->dev = dev;
+	dma->chancnt = MPC_DMA_CHANNELS;
+	dma->device_alloc_chan_resources = mpc_dma_alloc_chan_resources;
+	dma->device_free_chan_resources = mpc_dma_free_chan_resources;
+	dma->device_issue_pending = mpc_dma_issue_pending;
+	dma->device_is_tx_complete = mpc_dma_is_tx_complete;
+	dma->device_prep_dma_memcpy = mpc_dma_prep_memcpy;
+
+	INIT_LIST_HEAD(&dma->channels);
+	dma_cap_set(DMA_MEMCPY, dma->cap_mask);
+
+	for (i = 0; i < dma->chancnt; i++) {
+		mchan = &mdma->channels[i];
+
+		mchan->chan.device = dma;
+		mchan->chan.chan_id = i;
+		mchan->chan.cookie = 1;
+		mchan->completed_cookie = mchan->chan.cookie;
+
+		INIT_LIST_HEAD(&mchan->free);
+		INIT_LIST_HEAD(&mchan->prepared);
+		INIT_LIST_HEAD(&mchan->queued);
+		INIT_LIST_HEAD(&mchan->active);
+		INIT_LIST_HEAD(&mchan->completed);
+
+		spin_lock_init(&mchan->lock);
+		list_add_tail(&mchan->chan.device_node, &dma->channels);
+	}
+
+	tasklet_init(&mdma->tasklet, mpc_dma_tasklet, (unsigned long)mdma);
+
+	/*
+	 * Configure DMA Engine:
+	 * - Dynamic clock,
+	 * - Round-robin group arbitration,
+	 * - Round-robin channel arbitration.
+	 */
+	out_be32(&mdma->regs->dmacr, MPC_DMA_DMACR_EDCG |
+				MPC_DMA_DMACR_ERGA | MPC_DMA_DMACR_ERCA);
+
+	/* Disable hardware DMA requests */
+	out_be32(&mdma->regs->dmaerqh, 0);
+	out_be32(&mdma->regs->dmaerql, 0);
+
+	/* Disable error interrupts */
+	out_be32(&mdma->regs->dmaeeih, 0);
+	out_be32(&mdma->regs->dmaeeil, 0);
+
+	/* Clear interrupts status */
+	out_be32(&mdma->regs->dmainth, 0xFFFFFFFF);
+	out_be32(&mdma->regs->dmaintl, 0xFFFFFFFF);
+	out_be32(&mdma->regs->dmaerrh, 0xFFFFFFFF);
+	out_be32(&mdma->regs->dmaerrl, 0xFFFFFFFF);
+
+	/* Route interrupts to IPIC */
+	out_be32(&mdma->regs->dmaihsa, 0);
+	out_be32(&mdma->regs->dmailsa, 0);
+
+	/* Register DMA engine */
+	dev_set_drvdata(dev, mdma);
+	retval = dma_async_device_register(dma);
+	if (retval) {
+		devm_free_irq(dev, mdma->irq, mdma);
+		irq_dispose_mapping(mdma->irq);
+	}
+
+	return retval;
+}
+
+static int __devexit mpc_dma_remove(struct of_device *op)
+{
+	struct device *dev = &op->dev;
+	struct mpc_dma *mdma = dev_get_drvdata(dev);
+
+	dma_async_device_unregister(&mdma->dma);
+	devm_free_irq(dev, mdma->irq, mdma);
+	irq_dispose_mapping(mdma->irq);
+
+	return 0;
+}
+
+static struct of_device_id mpc_dma_match[] = {
+	{ .compatible = "fsl,mpc5121-dma", },
+	{},
+};
+
+static struct of_platform_driver mpc_dma_driver = {
+	.match_table	= mpc_dma_match,
+	.probe		= mpc_dma_probe,
+	.remove		= __devexit_p(mpc_dma_remove),
+	.driver		= {
+		.name	= DRV_NAME,
+		.owner	= THIS_MODULE,
+	},
+};
+
+static int __init mpc_dma_init(void)
+{
+	return of_register_platform_driver(&mpc_dma_driver);
+}
+module_init(mpc_dma_init);
+
+static void __exit mpc_dma_exit(void)
+{
+	of_unregister_platform_driver(&mpc_dma_driver);
+}
+module_exit(mpc_dma_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Piotr Ziecik <kosmo@semihalf.com>");