/*
   * Driver for the Atmel AHB DMA Controller (aka HDMA or DMAC on AT91 systems)
   *
   * Copyright (C) 2008 Atmel Corporation
   *
   * 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 supports the Atmel AHB DMA Controller,
   *
   * The driver has currently been tested with the Atmel AT91SAM9RL
   * and AT91SAM9G45 series.
   */
  
  #include <linux/clk.h>
  #include <linux/dmaengine.h>
  #include <linux/dma-mapping.h>
  #include <linux/dmapool.h>
  #include <linux/interrupt.h>
  #include <linux/module.h>
  #include <linux/platform_device.h>

  #include <linux/slab.h>

  
  #include "at_hdmac_regs.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	ATC_DEFAULT_CFG		(ATC_FIFOCFG_HALFFIFO)
  #define	ATC_DEFAULT_CTRLA	(0)

  #define	ATC_DEFAULT_CTRLB	(ATC_SIF(AT_DMA_MEM_IF) \
  				|ATC_DIF(AT_DMA_MEM_IF))

  
  /*
   * 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)");
  
  
  /* prototypes */
  static dma_cookie_t atc_tx_submit(struct dma_async_tx_descriptor *tx);
  
  
  /*----------------------------------------------------------------------*/
  
  static struct at_desc *atc_first_active(struct at_dma_chan *atchan)
  {
  	return list_first_entry(&atchan->active_list,
  				struct at_desc, desc_node);
  }
  
  static struct at_desc *atc_first_queued(struct at_dma_chan *atchan)
  {
  	return list_first_entry(&atchan->queue,
  				struct at_desc, desc_node);
  }
  
  /**

   * atc_alloc_descriptor - allocate and return an initialized descriptor

   * @chan: the channel to allocate descriptors for
   * @gfp_flags: GFP allocation flags
   *
   * Note: The ack-bit is positioned in the descriptor flag at creation time
   *       to make initial allocation more convenient. This bit will be cleared
   *       and control will be given to client at usage time (during
   *       preparation functions).
   */
  static struct at_desc *atc_alloc_descriptor(struct dma_chan *chan,
  					    gfp_t gfp_flags)
  {
  	struct at_desc	*desc = NULL;
  	struct at_dma	*atdma = to_at_dma(chan->device);
  	dma_addr_t phys;
  
  	desc = dma_pool_alloc(atdma->dma_desc_pool, gfp_flags, &phys);
  	if (desc) {
  		memset(desc, 0, sizeof(struct at_desc));

  		INIT_LIST_HEAD(&desc->tx_list);

  		dma_async_tx_descriptor_init(&desc->txd, chan);
  		/* txd.flags will be overwritten in prep functions */
  		desc->txd.flags = DMA_CTRL_ACK;
  		desc->txd.tx_submit = atc_tx_submit;
  		desc->txd.phys = phys;
  	}
  
  	return desc;
  }
  
  /**

   * atc_desc_get - get an unused descriptor from free_list

   * @atchan: channel we want a new descriptor for
   */
  static struct at_desc *atc_desc_get(struct at_dma_chan *atchan)
  {
  	struct at_desc *desc, *_desc;
  	struct at_desc *ret = NULL;

  	unsigned long flags;

  	unsigned int i = 0;
  	LIST_HEAD(tmp_list);

  	spin_lock_irqsave(&atchan->lock, flags);

  	list_for_each_entry_safe(desc, _desc, &atchan->free_list, desc_node) {
  		i++;
  		if (async_tx_test_ack(&desc->txd)) {
  			list_del(&desc->desc_node);
  			ret = desc;
  			break;
  		}
  		dev_dbg(chan2dev(&atchan->chan_common),
  				"desc %p not ACKed
  ", desc);
  	}

  	spin_unlock_irqrestore(&atchan->lock, flags);

  	dev_vdbg(chan2dev(&atchan->chan_common),
  		"scanned %u descriptors on freelist
  ", i);
  
  	/* no more descriptor available in initial pool: create one more */
  	if (!ret) {
  		ret = atc_alloc_descriptor(&atchan->chan_common, GFP_ATOMIC);
  		if (ret) {

  			spin_lock_irqsave(&atchan->lock, flags);

  			atchan->descs_allocated++;

  			spin_unlock_irqrestore(&atchan->lock, flags);

  		} else {
  			dev_err(chan2dev(&atchan->chan_common),
  					"not enough descriptors available
  ");
  		}
  	}
  
  	return ret;
  }
  
  /**
   * atc_desc_put - move a descriptor, including any children, to the free list
   * @atchan: channel we work on
   * @desc: descriptor, at the head of a chain, to move to free list
   */
  static void atc_desc_put(struct at_dma_chan *atchan, struct at_desc *desc)
  {
  	if (desc) {
  		struct at_desc *child;

  		unsigned long flags;

  		spin_lock_irqsave(&atchan->lock, flags);

  		list_for_each_entry(child, &desc->tx_list, desc_node)

  			dev_vdbg(chan2dev(&atchan->chan_common),
  					"moving child desc %p to freelist
  ",
  					child);

  		list_splice_init(&desc->tx_list, &atchan->free_list);

  		dev_vdbg(chan2dev(&atchan->chan_common),
  			 "moving desc %p to freelist
  ", desc);
  		list_add(&desc->desc_node, &atchan->free_list);

  		spin_unlock_irqrestore(&atchan->lock, flags);

  	}
  }
  
  /**

   * atc_desc_chain - build chain adding a descripor
   * @first: address of first descripor of the chain
   * @prev: address of previous descripor of the chain
   * @desc: descriptor to queue
   *
   * Called from prep_* functions
   */
  static void atc_desc_chain(struct at_desc **first, struct at_desc **prev,
  			   struct at_desc *desc)
  {
  	if (!(*first)) {
  		*first = desc;
  	} else {
  		/* inform the HW lli about chaining */
  		(*prev)->lli.dscr = desc->txd.phys;
  		/* insert the link descriptor to the LD ring */
  		list_add_tail(&desc->desc_node,
  				&(*first)->tx_list);
  	}
  	*prev = desc;
  }
  
  /**

   * atc_assign_cookie - compute and assign new cookie
   * @atchan: channel we work on

   * @desc: descriptor to assign cookie for

   *
   * Called with atchan->lock held and bh disabled
   */
  static dma_cookie_t
  atc_assign_cookie(struct at_dma_chan *atchan, struct at_desc *desc)
  {
  	dma_cookie_t cookie = atchan->chan_common.cookie;
  
  	if (++cookie < 0)
  		cookie = 1;
  
  	atchan->chan_common.cookie = cookie;
  	desc->txd.cookie = cookie;
  
  	return cookie;
  }
  
  /**
   * atc_dostart - starts the DMA engine for real
   * @atchan: the channel we want to start
   * @first: first descriptor in the list we want to begin with
   *
   * Called with atchan->lock held and bh disabled
   */
  static void atc_dostart(struct at_dma_chan *atchan, struct at_desc *first)
  {
  	struct at_dma	*atdma = to_at_dma(atchan->chan_common.device);
  
  	/* ASSERT:  channel is idle */
  	if (atc_chan_is_enabled(atchan)) {
  		dev_err(chan2dev(&atchan->chan_common),
  			"BUG: Attempted to start non-idle channel
  ");
  		dev_err(chan2dev(&atchan->chan_common),
  			"  channel: s0x%x d0x%x ctrl0x%x:0x%x l0x%x
  ",
  			channel_readl(atchan, SADDR),
  			channel_readl(atchan, DADDR),
  			channel_readl(atchan, CTRLA),
  			channel_readl(atchan, CTRLB),
  			channel_readl(atchan, DSCR));
  
  		/* The tasklet will hopefully advance the queue... */
  		return;
  	}
  
  	vdbg_dump_regs(atchan);
  
  	/* clear any pending interrupt */
  	while (dma_readl(atdma, EBCISR))
  		cpu_relax();
  
  	channel_writel(atchan, SADDR, 0);
  	channel_writel(atchan, DADDR, 0);
  	channel_writel(atchan, CTRLA, 0);
  	channel_writel(atchan, CTRLB, 0);
  	channel_writel(atchan, DSCR, first->txd.phys);
  	dma_writel(atdma, CHER, atchan->mask);
  
  	vdbg_dump_regs(atchan);
  }
  
  /**
   * atc_chain_complete - finish work for one transaction chain
   * @atchan: channel we work on
   * @desc: descriptor at the head of the chain we want do complete
   *
   * Called with atchan->lock held and bh disabled */
  static void
  atc_chain_complete(struct at_dma_chan *atchan, struct at_desc *desc)
  {

  	struct dma_async_tx_descriptor	*txd = &desc->txd;
  
  	dev_vdbg(chan2dev(&atchan->chan_common),
  		"descriptor %u complete
  ", txd->cookie);
  
  	atchan->completed_cookie = txd->cookie;

  
  	/* move children to free_list */

  	list_splice_init(&desc->tx_list, &atchan->free_list);

  	/* move myself to free_list */
  	list_move(&desc->desc_node, &atchan->free_list);

  	/* unmap dma addresses (not on slave channels) */

  	if (!atchan->chan_common.private) {
  		struct device *parent = chan2parent(&atchan->chan_common);
  		if (!(txd->flags & DMA_COMPL_SKIP_DEST_UNMAP)) {
  			if (txd->flags & DMA_COMPL_DEST_UNMAP_SINGLE)
  				dma_unmap_single(parent,
  						desc->lli.daddr,
  						desc->len, DMA_FROM_DEVICE);
  			else
  				dma_unmap_page(parent,
  						desc->lli.daddr,
  						desc->len, DMA_FROM_DEVICE);
  		}
  		if (!(txd->flags & DMA_COMPL_SKIP_SRC_UNMAP)) {
  			if (txd->flags & DMA_COMPL_SRC_UNMAP_SINGLE)
  				dma_unmap_single(parent,
  						desc->lli.saddr,
  						desc->len, DMA_TO_DEVICE);
  			else
  				dma_unmap_page(parent,
  						desc->lli.saddr,
  						desc->len, DMA_TO_DEVICE);
  		}

  	}

  	/* for cyclic transfers,
  	 * no need to replay callback function while stopping */

  	if (!atc_chan_is_cyclic(atchan)) {

  		dma_async_tx_callback	callback = txd->callback;
  		void			*param = txd->callback_param;
  
  		/*
  		 * The API requires that no submissions are done from a
  		 * callback, so we don't need to drop the lock here
  		 */
  		if (callback)
  			callback(param);
  	}

  
  	dma_run_dependencies(txd);
  }
  
  /**
   * atc_complete_all - finish work for all transactions
   * @atchan: channel to complete transactions for
   *
   * Eventually submit queued descriptors if any
   *
   * Assume channel is idle while calling this function
   * Called with atchan->lock held and bh disabled
   */
  static void atc_complete_all(struct at_dma_chan *atchan)
  {
  	struct at_desc *desc, *_desc;
  	LIST_HEAD(list);
  
  	dev_vdbg(chan2dev(&atchan->chan_common), "complete all
  ");
  
  	BUG_ON(atc_chan_is_enabled(atchan));
  
  	/*
  	 * Submit queued descriptors ASAP, i.e. before we go through
  	 * the completed ones.
  	 */
  	if (!list_empty(&atchan->queue))
  		atc_dostart(atchan, atc_first_queued(atchan));
  	/* empty active_list now it is completed */
  	list_splice_init(&atchan->active_list, &list);
  	/* empty queue list by moving descriptors (if any) to active_list */
  	list_splice_init(&atchan->queue, &atchan->active_list);
  
  	list_for_each_entry_safe(desc, _desc, &list, desc_node)
  		atc_chain_complete(atchan, desc);
  }
  
  /**
   * atc_cleanup_descriptors - cleanup up finished descriptors in active_list
   * @atchan: channel to be cleaned up
   *
   * Called with atchan->lock held and bh disabled
   */
  static void atc_cleanup_descriptors(struct at_dma_chan *atchan)
  {
  	struct at_desc	*desc, *_desc;
  	struct at_desc	*child;
  
  	dev_vdbg(chan2dev(&atchan->chan_common), "cleanup descriptors
  ");
  
  	list_for_each_entry_safe(desc, _desc, &atchan->active_list, desc_node) {
  		if (!(desc->lli.ctrla & ATC_DONE))
  			/* This one is currently in progress */
  			return;

  		list_for_each_entry(child, &desc->tx_list, desc_node)

  			if (!(child->lli.ctrla & ATC_DONE))
  				/* Currently in progress */
  				return;
  
  		/*
  		 * No descriptors so far seem to be in progress, i.e.
  		 * this chain must be done.
  		 */
  		atc_chain_complete(atchan, desc);
  	}
  }
  
  /**
   * atc_advance_work - at the end of a transaction, move forward
   * @atchan: channel where the transaction ended
   *
   * Called with atchan->lock held and bh disabled
   */
  static void atc_advance_work(struct at_dma_chan *atchan)
  {
  	dev_vdbg(chan2dev(&atchan->chan_common), "advance_work
  ");
  
  	if (list_empty(&atchan->active_list) ||
  	    list_is_singular(&atchan->active_list)) {
  		atc_complete_all(atchan);
  	} else {
  		atc_chain_complete(atchan, atc_first_active(atchan));
  		/* advance work */
  		atc_dostart(atchan, atc_first_active(atchan));
  	}
  }
  
  
  /**
   * atc_handle_error - handle errors reported by DMA controller
   * @atchan: channel where error occurs
   *
   * Called with atchan->lock held and bh disabled
   */
  static void atc_handle_error(struct at_dma_chan *atchan)
  {
  	struct at_desc *bad_desc;
  	struct at_desc *child;
  
  	/*
  	 * The descriptor currently at the head of the active list is
  	 * broked. Since we don't have any way to report errors, we'll
  	 * just have to scream loudly and try to carry on.
  	 */
  	bad_desc = atc_first_active(atchan);
  	list_del_init(&bad_desc->desc_node);
  
  	/* As we are stopped, take advantage to push queued descriptors
  	 * in active_list */
  	list_splice_init(&atchan->queue, atchan->active_list.prev);
  
  	/* Try to restart the controller */
  	if (!list_empty(&atchan->active_list))
  		atc_dostart(atchan, atc_first_active(atchan));
  
  	/*
  	 * 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->chan_common),
  			"Bad descriptor submitted for DMA!
  ");
  	dev_crit(chan2dev(&atchan->chan_common),
  			"  cookie: %d
  ", bad_desc->txd.cookie);
  	atc_dump_lli(atchan, &bad_desc->lli);

  	list_for_each_entry(child, &bad_desc->tx_list, desc_node)

  		atc_dump_lli(atchan, &child->lli);
  
  	/* Pretend the descriptor completed successfully */
  	atc_chain_complete(atchan, bad_desc);
  }

  /**
   * atc_handle_cyclic - at the end of a period, run callback function
   * @atchan: channel used for cyclic operations
   *
   * Called with atchan->lock held and bh disabled
   */
  static void atc_handle_cyclic(struct at_dma_chan *atchan)
  {
  	struct at_desc			*first = atc_first_active(atchan);
  	struct dma_async_tx_descriptor	*txd = &first->txd;
  	dma_async_tx_callback		callback = txd->callback;
  	void				*param = txd->callback_param;
  
  	dev_vdbg(chan2dev(&atchan->chan_common),
  			"new cyclic period llp 0x%08x
  ",
  			channel_readl(atchan, DSCR));
  
  	if (callback)
  		callback(param);
  }

  
  /*--  IRQ & Tasklet  ---------------------------------------------------*/
  
  static void atc_tasklet(unsigned long data)
  {
  	struct at_dma_chan *atchan = (struct at_dma_chan *)data;

  	unsigned long flags;

  	spin_lock_irqsave(&atchan->lock, flags);

  	if (test_and_clear_bit(ATC_IS_ERROR, &atchan->status))

  		atc_handle_error(atchan);

  	else if (atc_chan_is_cyclic(atchan))

  		atc_handle_cyclic(atchan);

  	else
  		atc_advance_work(atchan);

  	spin_unlock_irqrestore(&atchan->lock, flags);

  }
  
  static irqreturn_t at_dma_interrupt(int irq, void *dev_id)
  {
  	struct at_dma		*atdma = (struct at_dma *)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_common.dev,
  			"interrupt: status = 0x%08x, 0x%08x, 0x%08x
  ",
  			 status, imr, pending);
  
  		for (i = 0; i < atdma->dma_common.chancnt; i++) {
  			atchan = &atdma->chan[i];

  			if (pending & (AT_DMA_BTC(i) | AT_DMA_ERR(i))) {

  				if (pending & AT_DMA_ERR(i)) {
  					/* Disable channel on AHB error */

  					dma_writel(atdma, CHDR,
  						AT_DMA_RES(i) | atchan->mask);

  					/* Give information to tasklet */

  					set_bit(ATC_IS_ERROR, &atchan->status);

  				}
  				tasklet_schedule(&atchan->tasklet);
  				ret = IRQ_HANDLED;
  			}
  		}
  
  	} while (pending);
  
  	return ret;
  }
  
  
  /*--  DMA Engine API  --------------------------------------------------*/
  
  /**
   * atc_tx_submit - set the prepared descriptor(s) to be executed by the engine
   * @desc: descriptor at the head of the transaction chain
   *
   * Queue chain if DMA engine is working already
   *
   * Cookie increment and adding to active_list or queue must be atomic
   */
  static dma_cookie_t atc_tx_submit(struct dma_async_tx_descriptor *tx)
  {
  	struct at_desc		*desc = txd_to_at_desc(tx);
  	struct at_dma_chan	*atchan = to_at_dma_chan(tx->chan);
  	dma_cookie_t		cookie;

  	unsigned long		flags;

  	spin_lock_irqsave(&atchan->lock, flags);

  	cookie = atc_assign_cookie(atchan, desc);
  
  	if (list_empty(&atchan->active_list)) {
  		dev_vdbg(chan2dev(tx->chan), "tx_submit: started %u
  ",
  				desc->txd.cookie);
  		atc_dostart(atchan, desc);
  		list_add_tail(&desc->desc_node, &atchan->active_list);
  	} else {
  		dev_vdbg(chan2dev(tx->chan), "tx_submit: queued %u
  ",
  				desc->txd.cookie);
  		list_add_tail(&desc->desc_node, &atchan->queue);
  	}

  	spin_unlock_irqrestore(&atchan->lock, flags);

  
  	return cookie;
  }
  
  /**
   * 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_chan	*atchan = to_at_dma_chan(chan);
  	struct at_desc		*desc = NULL;
  	struct at_desc		*first = NULL;
  	struct at_desc		*prev = NULL;
  	size_t			xfer_count;
  	size_t			offset;
  	unsigned int		src_width;
  	unsigned int		dst_width;
  	u32			ctrla;
  	u32			ctrlb;
  
  	dev_vdbg(chan2dev(chan), "prep_dma_memcpy: d0x%x s0x%x l0x%zx f0x%lx
  ",
  			dest, src, len, flags);
  
  	if (unlikely(!len)) {
  		dev_dbg(chan2dev(chan), "prep_dma_memcpy: length is zero!
  ");
  		return NULL;
  	}
  
  	ctrla =   ATC_DEFAULT_CTRLA;

  	ctrlb =   ATC_DEFAULT_CTRLB | ATC_IEN

  		| ATC_SRC_ADDR_MODE_INCR
  		| ATC_DST_ADDR_MODE_INCR
  		| ATC_FC_MEM2MEM;
  
  	/*
  	 * We can be a lot more clever here, but this should take care
  	 * of the most common optimization.
  	 */
  	if (!((src | dest  | len) & 3)) {
  		ctrla |= ATC_SRC_WIDTH_WORD | ATC_DST_WIDTH_WORD;
  		src_width = dst_width = 2;
  	} else if (!((src | dest | len) & 1)) {
  		ctrla |= ATC_SRC_WIDTH_HALFWORD | ATC_DST_WIDTH_HALFWORD;
  		src_width = dst_width = 1;
  	} else {
  		ctrla |= ATC_SRC_WIDTH_BYTE | ATC_DST_WIDTH_BYTE;
  		src_width = dst_width = 0;
  	}
  
  	for (offset = 0; offset < len; offset += xfer_count << src_width) {
  		xfer_count = min_t(size_t, (len - offset) >> src_width,
  				ATC_BTSIZE_MAX);
  
  		desc = atc_desc_get(atchan);
  		if (!desc)
  			goto err_desc_get;
  
  		desc->lli.saddr = src + offset;
  		desc->lli.daddr = dest + offset;
  		desc->lli.ctrla = ctrla | xfer_count;
  		desc->lli.ctrlb = ctrlb;
  
  		desc->txd.cookie = 0;

  		atc_desc_chain(&first, &prev, desc);

  	}
  
  	/* First descriptor of the chain embedds additional information */
  	first->txd.cookie = -EBUSY;
  	first->len = len;
  
  	/* set end-of-link to the last link descriptor of list*/
  	set_desc_eol(desc);

  	first->txd.flags = flags; /* client is in control of this ack */

  
  	return &first->txd;
  
  err_desc_get:
  	atc_desc_put(atchan, first);
  	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
   */
  static struct dma_async_tx_descriptor *
  atc_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
  		unsigned int sg_len, enum dma_data_direction direction,
  		unsigned long flags)
  {
  	struct at_dma_chan	*atchan = to_at_dma_chan(chan);
  	struct at_dma_slave	*atslave = chan->private;
  	struct at_desc		*first = NULL;
  	struct at_desc		*prev = NULL;
  	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
  ",
  			sg_len,

  			direction == DMA_TO_DEVICE ? "TO DEVICE" : "FROM DEVICE",
  			flags);
  
  	if (unlikely(!atslave || !sg_len)) {
  		dev_dbg(chan2dev(chan), "prep_dma_memcpy: length is zero!
  ");
  		return NULL;
  	}
  
  	reg_width = atslave->reg_width;

  	ctrla = ATC_DEFAULT_CTRLA | atslave->ctrla;

  	ctrlb = ATC_IEN;

  
  	switch (direction) {
  	case DMA_TO_DEVICE:
  		ctrla |=  ATC_DST_WIDTH(reg_width);
  		ctrlb |=  ATC_DST_ADDR_MODE_FIXED
  			| ATC_SRC_ADDR_MODE_INCR

  			| ATC_FC_MEM2PER
  			| ATC_SIF(AT_DMA_MEM_IF) | ATC_DIF(AT_DMA_PER_IF);

  		reg = atslave->tx_reg;
  		for_each_sg(sgl, sg, sg_len, i) {
  			struct at_desc	*desc;
  			u32		len;
  			u32		mem;
  
  			desc = atc_desc_get(atchan);
  			if (!desc)
  				goto err_desc_get;

  			mem = sg_dma_address(sg);

  			len = sg_dma_len(sg);
  			mem_width = 2;
  			if (unlikely(mem & 3 || len & 3))
  				mem_width = 0;
  
  			desc->lli.saddr = mem;
  			desc->lli.daddr = reg;
  			desc->lli.ctrla = ctrla
  					| ATC_SRC_WIDTH(mem_width)
  					| len >> mem_width;
  			desc->lli.ctrlb = ctrlb;

  			atc_desc_chain(&first, &prev, desc);

  			total_len += len;
  		}
  		break;
  	case DMA_FROM_DEVICE:
  		ctrla |=  ATC_SRC_WIDTH(reg_width);
  		ctrlb |=  ATC_DST_ADDR_MODE_INCR
  			| ATC_SRC_ADDR_MODE_FIXED

  			| ATC_FC_PER2MEM
  			| ATC_SIF(AT_DMA_PER_IF) | ATC_DIF(AT_DMA_MEM_IF);

  
  		reg = atslave->rx_reg;
  		for_each_sg(sgl, sg, sg_len, i) {
  			struct at_desc	*desc;
  			u32		len;
  			u32		mem;
  
  			desc = atc_desc_get(atchan);
  			if (!desc)
  				goto err_desc_get;

  			mem = sg_dma_address(sg);

  			len = sg_dma_len(sg);
  			mem_width = 2;
  			if (unlikely(mem & 3 || len & 3))
  				mem_width = 0;
  
  			desc->lli.saddr = reg;
  			desc->lli.daddr = mem;
  			desc->lli.ctrla = ctrla
  					| ATC_DST_WIDTH(mem_width)

  					| len >> reg_width;

  			desc->lli.ctrlb = ctrlb;

  			atc_desc_chain(&first, &prev, desc);

  			total_len += len;
  		}
  		break;
  	default:
  		return NULL;
  	}
  
  	/* set end-of-link to the last link descriptor of list*/
  	set_desc_eol(prev);
  
  	/* First descriptor of the chain embedds additional information */
  	first->txd.cookie = -EBUSY;
  	first->len = total_len;

  	/* first link descriptor of list is responsible of flags */
  	first->txd.flags = flags; /* client is in control of this ack */

  
  	return &first->txd;
  
  err_desc_get:
  	dev_err(chan2dev(chan), "not enough descriptors available
  ");
  	atc_desc_put(atchan, first);
  	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, enum dma_data_direction direction)
  {
  	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;
  	if (unlikely(!(direction & (DMA_TO_DEVICE | DMA_FROM_DEVICE))))
  		goto err_out;
  
  	return 0;
  
  err_out:
  	return -EINVAL;
  }
  
  /**
   * atc_dma_cyclic_fill_desc - Fill one period decriptor
   */
  static int
  atc_dma_cyclic_fill_desc(struct at_dma_slave *atslave, struct at_desc *desc,
  		unsigned int period_index, dma_addr_t buf_addr,
  		size_t period_len, enum dma_data_direction direction)
  {
  	u32		ctrla;
  	unsigned int	reg_width = atslave->reg_width;
  
  	/* prepare common CRTLA value */
  	ctrla =   ATC_DEFAULT_CTRLA | atslave->ctrla
  		| ATC_DST_WIDTH(reg_width)
  		| ATC_SRC_WIDTH(reg_width)
  		| period_len >> reg_width;
  
  	switch (direction) {
  	case DMA_TO_DEVICE:
  		desc->lli.saddr = buf_addr + (period_len * period_index);
  		desc->lli.daddr = atslave->tx_reg;
  		desc->lli.ctrla = ctrla;

  		desc->lli.ctrlb = ATC_DST_ADDR_MODE_FIXED

  				| ATC_SRC_ADDR_MODE_INCR

  				| ATC_FC_MEM2PER
  				| ATC_SIF(AT_DMA_MEM_IF)
  				| ATC_DIF(AT_DMA_PER_IF);

  		break;
  
  	case DMA_FROM_DEVICE:
  		desc->lli.saddr = atslave->rx_reg;
  		desc->lli.daddr = buf_addr + (period_len * period_index);
  		desc->lli.ctrla = ctrla;

  		desc->lli.ctrlb = ATC_DST_ADDR_MODE_INCR

  				| ATC_SRC_ADDR_MODE_FIXED

  				| ATC_FC_PER2MEM
  				| ATC_SIF(AT_DMA_PER_IF)
  				| ATC_DIF(AT_DMA_MEM_IF);

  		break;
  
  	default:
  		return -EINVAL;
  	}
  
  	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
   */
  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_data_direction direction)
  {
  	struct at_dma_chan	*atchan = to_at_dma_chan(chan);
  	struct at_dma_slave	*atslave = chan->private;
  	struct at_desc		*first = NULL;
  	struct at_desc		*prev = NULL;
  	unsigned long		was_cyclic;
  	unsigned int		periods = buf_len / period_len;
  	unsigned int		i;
  
  	dev_vdbg(chan2dev(chan), "prep_dma_cyclic: %s buf@0x%08x - %d (%d/%d)
  ",
  			direction == DMA_TO_DEVICE ? "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!
  ");
  		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!
  ");
  		return NULL;
  	}
  
  	/* Check for too big/unaligned periods and unaligned DMA buffer */
  	if (atc_dma_cyclic_check_values(atslave->reg_width, buf_addr,
  					period_len, direction))
  		goto err_out;
  
  	/* build cyclic linked list */
  	for (i = 0; i < periods; i++) {
  		struct at_desc	*desc;
  
  		desc = atc_desc_get(atchan);
  		if (!desc)
  			goto err_desc_get;
  
  		if (atc_dma_cyclic_fill_desc(atslave, desc, i, buf_addr,
  						period_len, direction))
  			goto err_desc_get;
  
  		atc_desc_chain(&first, &prev, desc);
  	}
  
  	/* lets make a cyclic list */
  	prev->lli.dscr = first->txd.phys;
  
  	/* First descriptor of the chain embedds additional information */
  	first->txd.cookie = -EBUSY;
  	first->len = buf_len;
  
  	return &first->txd;
  
  err_desc_get:
  	dev_err(chan2dev(chan), "not enough descriptors available
  ");
  	atc_desc_put(atchan, first);
  err_out:
  	clear_bit(ATC_IS_CYCLIC, &atchan->status);
  	return NULL;
  }

  static int atc_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
  		       unsigned long arg)

  {
  	struct at_dma_chan	*atchan = to_at_dma_chan(chan);
  	struct at_dma		*atdma = to_at_dma(chan->device);

  	int			chan_id = atchan->chan_common.chan_id;

  	unsigned long		flags;

  	LIST_HEAD(list);

  	dev_vdbg(chan2dev(chan), "atc_control (%d)
  ", cmd);

  	if (cmd == DMA_PAUSE) {

  		spin_lock_irqsave(&atchan->lock, flags);

  		dma_writel(atdma, CHER, AT_DMA_SUSP(chan_id));

  		set_bit(ATC_IS_PAUSED, &atchan->status);

  		spin_unlock_irqrestore(&atchan->lock, flags);

  	} else if (cmd == DMA_RESUME) {

  		if (!atc_chan_is_paused(atchan))

  			return 0;

  		spin_lock_irqsave(&atchan->lock, flags);

  		dma_writel(atdma, CHDR, AT_DMA_RES(chan_id));
  		clear_bit(ATC_IS_PAUSED, &atchan->status);

  		spin_unlock_irqrestore(&atchan->lock, flags);

  	} else if (cmd == DMA_TERMINATE_ALL) {
  		struct at_desc	*desc, *_desc;
  		/*
  		 * 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->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();
  
  		/* active_list entries will end up before queued entries */
  		list_splice_init(&atchan->queue, &list);
  		list_splice_init(&atchan->active_list, &list);
  
  		/* Flush all pending and queued descriptors */
  		list_for_each_entry_safe(desc, _desc, &list, desc_node)
  			atc_chain_complete(atchan, desc);
  
  		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->lock, flags);

  	} else {
  		return -ENXIO;
  	}

  	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);
  	dma_cookie_t		last_used;
  	dma_cookie_t		last_complete;

  	unsigned long		flags;

  	enum dma_status		ret;

  	spin_lock_irqsave(&atchan->lock, flags);

  
  	last_complete = atchan->completed_cookie;
  	last_used = chan->cookie;
  
  	ret = dma_async_is_complete(cookie, last_complete, last_used);
  	if (ret != DMA_SUCCESS) {
  		atc_cleanup_descriptors(atchan);
  
  		last_complete = atchan->completed_cookie;
  		last_used = chan->cookie;
  
  		ret = dma_async_is_complete(cookie, last_complete, last_used);
  	}

  	spin_unlock_irqrestore(&atchan->lock, flags);

  	if (ret != DMA_SUCCESS)
  		dma_set_tx_state(txstate, last_complete, last_used,
  			atc_first_active(atchan)->len);
  	else
  		dma_set_tx_state(txstate, last_complete, last_used, 0);

  	if (atc_chan_is_paused(atchan))

  		ret = DMA_PAUSED;
  
  	dev_vdbg(chan2dev(chan), "tx_status %d: cookie = %d (d%d, u%d)
  ",
  		 ret, cookie, last_complete ? last_complete : 0,

  		 last_used ? last_used : 0);

  
  	return ret;
  }
  
  /**
   * atc_issue_pending - try to finish work
   * @chan: target DMA channel
   */
  static void atc_issue_pending(struct dma_chan *chan)
  {
  	struct at_dma_chan	*atchan = to_at_dma_chan(chan);

  	unsigned long		flags;

  
  	dev_vdbg(chan2dev(chan), "issue_pending
  ");

  	/* Not needed for cyclic transfers */

  	if (atc_chan_is_cyclic(atchan))

  		return;

  	spin_lock_irqsave(&atchan->lock, flags);

  	if (!atc_chan_is_enabled(atchan)) {

  		atc_advance_work(atchan);

  	}

  	spin_unlock_irqrestore(&atchan->lock, flags);

  }
  
  /**
   * atc_alloc_chan_resources - allocate resources for DMA channel
   * @chan: allocate descriptor resources for this channel
   * @client: current client requesting the channel be ready for requests
   *
   * 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_desc		*desc;

  	struct at_dma_slave	*atslave;

  	unsigned long		flags;

  	int			i;

  	u32			cfg;

  	LIST_HEAD(tmp_list);
  
  	dev_vdbg(chan2dev(chan), "alloc_chan_resources
  ");
  
  	/* ASSERT:  channel is idle */
  	if (atc_chan_is_enabled(atchan)) {
  		dev_dbg(chan2dev(chan), "DMA channel not idle ?
  ");
  		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_common.dev);
  
  		/* if cfg configuration specified take it instad of default */
  		if (atslave->cfg)
  			cfg = atslave->cfg;
  	}
  
  	/* have we already been set up?
  	 * reconfigure channel but no need to reallocate descriptors */

  	if (!list_empty(&atchan->free_list))
  		return atchan->descs_allocated;
  
  	/* Allocate initial pool of descriptors */
  	for (i = 0; i < init_nr_desc_per_channel; i++) {
  		desc = atc_alloc_descriptor(chan, GFP_KERNEL);
  		if (!desc) {
  			dev_err(atdma->dma_common.dev,
  				"Only %d initial descriptors
  ", i);
  			break;
  		}
  		list_add_tail(&desc->desc_node, &tmp_list);
  	}

  	spin_lock_irqsave(&atchan->lock, flags);

  	atchan->descs_allocated = i;
  	list_splice(&tmp_list, &atchan->free_list);
  	atchan->completed_cookie = chan->cookie = 1;

  	spin_unlock_irqrestore(&atchan->lock, flags);

  
  	/* channel parameters */

  	channel_writel(atchan, CFG, cfg);

  
  	dev_dbg(chan2dev(chan),
  		"alloc_chan_resources: allocated %d descriptors
  ",
  		atchan->descs_allocated);
  
  	return atchan->descs_allocated;
  }
  
  /**
   * 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);
  	struct at_dma		*atdma = to_at_dma(chan->device);
  	struct at_desc		*desc, *_desc;
  	LIST_HEAD(list);
  
  	dev_dbg(chan2dev(chan), "free_chan_resources: (descs allocated=%u)
  ",
  		atchan->descs_allocated);
  
  	/* ASSERT:  channel is idle */
  	BUG_ON(!list_empty(&atchan->active_list));
  	BUG_ON(!list_empty(&atchan->queue));
  	BUG_ON(atc_chan_is_enabled(atchan));
  
  	list_for_each_entry_safe(desc, _desc, &atchan->free_list, desc_node) {
  		dev_vdbg(chan2dev(chan), "  freeing descriptor %p
  ", desc);
  		list_del(&desc->desc_node);
  		/* free link descriptor */
  		dma_pool_free(atdma->dma_desc_pool, desc, desc->txd.phys);
  	}
  	list_splice_init(&atchan->free_list, &list);
  	atchan->descs_allocated = 0;

  	atchan->status = 0;

  
  	dev_vdbg(chan2dev(chan), "free_chan_resources: done
  ");
  }
  
  
  /*--  Module Management  -----------------------------------------------*/
  
  /**
   * 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_platform_data *pdata;
  	struct resource		*io;
  	struct at_dma		*atdma;
  	size_t			size;
  	int			irq;
  	int			err;
  	int			i;
  
  	/* get DMA Controller parameters from platform */
  	pdata = pdev->dev.platform_data;
  	if (!pdata || pdata->nr_channels > AT_DMA_MAX_NR_CHANNELS)
  		return -EINVAL;
  
  	io = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	if (!io)
  		return -EINVAL;
  
  	irq = platform_get_irq(pdev, 0);
  	if (irq < 0)
  		return irq;
  
  	size = sizeof(struct at_dma);
  	size += pdata->nr_channels * sizeof(struct at_dma_chan);
  	atdma = kzalloc(size, GFP_KERNEL);
  	if (!atdma)
  		return -ENOMEM;
  
  	/* discover transaction capabilites from the platform data */
  	atdma->dma_common.cap_mask = pdata->cap_mask;
  	atdma->all_chan_mask = (1 << pdata->nr_channels) - 1;

  	size = resource_size(io);

  	if (!request_mem_region(io->start, size, pdev->dev.driver->name)) {
  		err = -EBUSY;
  		goto err_kfree;
  	}
  
  	atdma->regs = ioremap(io->start, size);
  	if (!atdma->regs) {
  		err = -ENOMEM;
  		goto err_release_r;
  	}
  
  	atdma->clk = clk_get(&pdev->dev, "dma_clk");
  	if (IS_ERR(atdma->clk)) {
  		err = PTR_ERR(atdma->clk);
  		goto err_clk;
  	}
  	clk_enable(atdma->clk);
  
  	/* 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->dma_desc_pool = dma_pool_create("at_hdmac_desc_pool",
  			&pdev->dev, sizeof(struct at_desc),
  			4 /* word alignment */, 0);
  	if (!atdma->dma_desc_pool) {
  		dev_err(&pdev->dev, "No memory for descriptors dma pool
  ");
  		err = -ENOMEM;
  		goto err_pool_create;
  	}
  
  	/* clear any pending interrupt */
  	while (dma_readl(atdma, EBCISR))
  		cpu_relax();
  
  	/* initialize channels related values */
  	INIT_LIST_HEAD(&atdma->dma_common.channels);

  	for (i = 0; i < pdata->nr_channels; i++) {

  		struct at_dma_chan	*atchan = &atdma->chan[i];
  
  		atchan->chan_common.device = &atdma->dma_common;
  		atchan->chan_common.cookie = atchan->completed_cookie = 1;

  		list_add_tail(&atchan->chan_common.device_node,
  				&atdma->dma_common.channels);
  
  		atchan->ch_regs = atdma->regs + ch_regs(i);
  		spin_lock_init(&atchan->lock);
  		atchan->mask = 1 << i;
  
  		INIT_LIST_HEAD(&atchan->active_list);
  		INIT_LIST_HEAD(&atchan->queue);
  		INIT_LIST_HEAD(&atchan->free_list);
  
  		tasklet_init(&atchan->tasklet, atc_tasklet,
  				(unsigned long)atchan);
  		atc_enable_irq(atchan);
  	}
  
  	/* set base routines */
  	atdma->dma_common.device_alloc_chan_resources = atc_alloc_chan_resources;
  	atdma->dma_common.device_free_chan_resources = atc_free_chan_resources;

  	atdma->dma_common.device_tx_status = atc_tx_status;

  	atdma->dma_common.device_issue_pending = atc_issue_pending;
  	atdma->dma_common.dev = &pdev->dev;
  
  	/* set prep routines based on capability */
  	if (dma_has_cap(DMA_MEMCPY, atdma->dma_common.cap_mask))
  		atdma->dma_common.device_prep_dma_memcpy = atc_prep_dma_memcpy;

  	if (dma_has_cap(DMA_SLAVE, atdma->dma_common.cap_mask)) {

  		atdma->dma_common.device_prep_slave_sg = atc_prep_slave_sg;

  		/* controller can do slave DMA: can trigger cyclic transfers */
  		dma_cap_set(DMA_CYCLIC, atdma->dma_common.cap_mask);

  		atdma->dma_common.device_prep_dma_cyclic = atc_prep_dma_cyclic;

  		atdma->dma_common.device_control = atc_control;

  	}

  	dma_writel(atdma, EN, AT_DMA_ENABLE);
  
  	dev_info(&pdev->dev, "Atmel AHB DMA Controller ( %s%s), %d channels
  ",
  	  dma_has_cap(DMA_MEMCPY, atdma->dma_common.cap_mask) ? "cpy " : "",
  	  dma_has_cap(DMA_SLAVE, atdma->dma_common.cap_mask)  ? "slave " : "",

  	  pdata->nr_channels);

  
  	dma_async_device_register(&atdma->dma_common);
  
  	return 0;
  
  err_pool_create:
  	platform_set_drvdata(pdev, NULL);
  	free_irq(platform_get_irq(pdev, 0), atdma);
  err_irq:
  	clk_disable(atdma->clk);
  	clk_put(atdma->clk);
  err_clk:
  	iounmap(atdma->regs);
  	atdma->regs = NULL;
  err_release_r:
  	release_mem_region(io->start, size);
  err_kfree:
  	kfree(atdma);
  	return err;
  }
  
  static int __exit at_dma_remove(struct platform_device *pdev)
  {
  	struct at_dma		*atdma = platform_get_drvdata(pdev);
  	struct dma_chan		*chan, *_chan;
  	struct resource		*io;
  
  	at_dma_off(atdma);
  	dma_async_device_unregister(&atdma->dma_common);
  
  	dma_pool_destroy(atdma->dma_desc_pool);
  	platform_set_drvdata(pdev, NULL);
  	free_irq(platform_get_irq(pdev, 0), atdma);
  
  	list_for_each_entry_safe(chan, _chan, &atdma->dma_common.channels,
  			device_node) {
  		struct at_dma_chan	*atchan = to_at_dma_chan(chan);
  
  		/* Disable interrupts */
  		atc_disable_irq(atchan);
  		tasklet_disable(&atchan->tasklet);
  
  		tasklet_kill(&atchan->tasklet);
  		list_del(&chan->device_node);
  	}
  
  	clk_disable(atdma->clk);
  	clk_put(atdma->clk);
  
  	iounmap(atdma->regs);
  	atdma->regs = NULL;
  
  	io = platform_get_resource(pdev, IORESOURCE_MEM, 0);

  	release_mem_region(io->start, resource_size(io));

  
  	kfree(atdma);
  
  	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(atdma->clk);
  }

  static int at_dma_prepare(struct device *dev)
  {
  	struct platform_device *pdev = to_platform_device(dev);
  	struct at_dma *atdma = platform_get_drvdata(pdev);
  	struct dma_chan *chan, *_chan;
  
  	list_for_each_entry_safe(chan, _chan, &atdma->dma_common.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->chan_common;
  
  	/* 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
  ");
  		atc_control(chan, DMA_PAUSE, 0);
  	}
  
  	/* 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 platform_device *pdev = to_platform_device(dev);
  	struct at_dma *atdma = platform_get_drvdata(pdev);

  	struct dma_chan *chan, *_chan;

  	/* preserve data */
  	list_for_each_entry_safe(chan, _chan, &atdma->dma_common.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(atdma->clk);
  	return 0;
  }

  static void atc_resume_cyclic(struct at_dma_chan *atchan)
  {
  	struct at_dma	*atdma = to_at_dma(atchan->chan_common.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 platform_device *pdev = to_platform_device(dev);
  	struct at_dma *atdma = platform_get_drvdata(pdev);

  	struct dma_chan *chan, *_chan;

  	/* bring back DMA controller */

  	clk_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_common.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 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		= __exit_p(at_dma_remove),
  	.shutdown	= at_dma_shutdown,

  	.driver = {
  		.name	= "at_hdmac",

  		.pm	= &at_dma_dev_pm_ops,

  	},
  };
  
  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_LICENSE("GPL");
  MODULE_ALIAS("platform:at_hdmac");