/*
   * Driver for the Cirrus Logic EP93xx DMA Controller
   *
   * Copyright (C) 2011 Mika Westerberg
   *
   * DMA M2P implementation is based on the original
   * arch/arm/mach-ep93xx/dma-m2p.c which has following copyrights:
   *
   *   Copyright (C) 2006 Lennert Buytenhek <buytenh@wantstofly.org>
   *   Copyright (C) 2006 Applied Data Systems
   *   Copyright (C) 2009 Ryan Mallon <rmallon@gmail.com>
   *
   * This driver is based on dw_dmac and amba-pl08x drivers.
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation; either version 2 of the License, or
   * (at your option) any later version.
   */
  
  #include <linux/clk.h>
  #include <linux/init.h>
  #include <linux/interrupt.h>
  #include <linux/dmaengine.h>
  #include <linux/module.h>
  #include <linux/platform_device.h>
  #include <linux/slab.h>
  
  #include <linux/platform_data/dma-ep93xx.h>
  
  #include "dmaengine.h"
  
  /* M2P registers */
  #define M2P_CONTROL			0x0000
  #define M2P_CONTROL_STALLINT		BIT(0)
  #define M2P_CONTROL_NFBINT		BIT(1)
  #define M2P_CONTROL_CH_ERROR_INT	BIT(3)
  #define M2P_CONTROL_ENABLE		BIT(4)
  #define M2P_CONTROL_ICE			BIT(6)
  
  #define M2P_INTERRUPT			0x0004
  #define M2P_INTERRUPT_STALL		BIT(0)
  #define M2P_INTERRUPT_NFB		BIT(1)
  #define M2P_INTERRUPT_ERROR		BIT(3)
  
  #define M2P_PPALLOC			0x0008
  #define M2P_STATUS			0x000c
  
  #define M2P_MAXCNT0			0x0020
  #define M2P_BASE0			0x0024
  #define M2P_MAXCNT1			0x0030
  #define M2P_BASE1			0x0034
  
  #define M2P_STATE_IDLE			0
  #define M2P_STATE_STALL			1
  #define M2P_STATE_ON			2
  #define M2P_STATE_NEXT			3
  
  /* M2M registers */
  #define M2M_CONTROL			0x0000
  #define M2M_CONTROL_DONEINT		BIT(2)
  #define M2M_CONTROL_ENABLE		BIT(3)
  #define M2M_CONTROL_START		BIT(4)
  #define M2M_CONTROL_DAH			BIT(11)
  #define M2M_CONTROL_SAH			BIT(12)
  #define M2M_CONTROL_PW_SHIFT		9
  #define M2M_CONTROL_PW_8		(0 << M2M_CONTROL_PW_SHIFT)
  #define M2M_CONTROL_PW_16		(1 << M2M_CONTROL_PW_SHIFT)
  #define M2M_CONTROL_PW_32		(2 << M2M_CONTROL_PW_SHIFT)
  #define M2M_CONTROL_PW_MASK		(3 << M2M_CONTROL_PW_SHIFT)
  #define M2M_CONTROL_TM_SHIFT		13
  #define M2M_CONTROL_TM_TX		(1 << M2M_CONTROL_TM_SHIFT)
  #define M2M_CONTROL_TM_RX		(2 << M2M_CONTROL_TM_SHIFT)
  #define M2M_CONTROL_NFBINT		BIT(21)
  #define M2M_CONTROL_RSS_SHIFT		22
  #define M2M_CONTROL_RSS_SSPRX		(1 << M2M_CONTROL_RSS_SHIFT)
  #define M2M_CONTROL_RSS_SSPTX		(2 << M2M_CONTROL_RSS_SHIFT)
  #define M2M_CONTROL_RSS_IDE		(3 << M2M_CONTROL_RSS_SHIFT)
  #define M2M_CONTROL_NO_HDSK		BIT(24)
  #define M2M_CONTROL_PWSC_SHIFT		25
  
  #define M2M_INTERRUPT			0x0004
  #define M2M_INTERRUPT_MASK		6
  
  #define M2M_STATUS			0x000c
  #define M2M_STATUS_CTL_SHIFT		1
  #define M2M_STATUS_CTL_IDLE		(0 << M2M_STATUS_CTL_SHIFT)
  #define M2M_STATUS_CTL_STALL		(1 << M2M_STATUS_CTL_SHIFT)
  #define M2M_STATUS_CTL_MEMRD		(2 << M2M_STATUS_CTL_SHIFT)
  #define M2M_STATUS_CTL_MEMWR		(3 << M2M_STATUS_CTL_SHIFT)
  #define M2M_STATUS_CTL_BWCWAIT		(4 << M2M_STATUS_CTL_SHIFT)
  #define M2M_STATUS_CTL_MASK		(7 << M2M_STATUS_CTL_SHIFT)
  #define M2M_STATUS_BUF_SHIFT		4
  #define M2M_STATUS_BUF_NO		(0 << M2M_STATUS_BUF_SHIFT)
  #define M2M_STATUS_BUF_ON		(1 << M2M_STATUS_BUF_SHIFT)
  #define M2M_STATUS_BUF_NEXT		(2 << M2M_STATUS_BUF_SHIFT)
  #define M2M_STATUS_BUF_MASK		(3 << M2M_STATUS_BUF_SHIFT)
  #define M2M_STATUS_DONE			BIT(6)
  
  #define M2M_BCR0			0x0010
  #define M2M_BCR1			0x0014
  #define M2M_SAR_BASE0			0x0018
  #define M2M_SAR_BASE1			0x001c
  #define M2M_DAR_BASE0			0x002c
  #define M2M_DAR_BASE1			0x0030
  
  #define DMA_MAX_CHAN_BYTES		0xffff
  #define DMA_MAX_CHAN_DESCRIPTORS	32
  
  struct ep93xx_dma_engine;
  
  /**
   * struct ep93xx_dma_desc - EP93xx specific transaction descriptor
   * @src_addr: source address of the transaction
   * @dst_addr: destination address of the transaction
   * @size: size of the transaction (in bytes)
   * @complete: this descriptor is completed
   * @txd: dmaengine API descriptor
   * @tx_list: list of linked descriptors
   * @node: link used for putting this into a channel queue
   */
  struct ep93xx_dma_desc {
  	u32				src_addr;
  	u32				dst_addr;
  	size_t				size;
  	bool				complete;
  	struct dma_async_tx_descriptor	txd;
  	struct list_head		tx_list;
  	struct list_head		node;
  };
  
  /**
   * struct ep93xx_dma_chan - an EP93xx DMA M2P/M2M channel
   * @chan: dmaengine API channel
   * @edma: pointer to to the engine device
   * @regs: memory mapped registers
   * @irq: interrupt number of the channel
   * @clk: clock used by this channel
   * @tasklet: channel specific tasklet used for callbacks
   * @lock: lock protecting the fields following
   * @flags: flags for the channel
   * @buffer: which buffer to use next (0/1)
   * @active: flattened chain of descriptors currently being processed
   * @queue: pending descriptors which are handled next
   * @free_list: list of free descriptors which can be used
   * @runtime_addr: physical address currently used as dest/src (M2M only). This
   *                is set via %DMA_SLAVE_CONFIG before slave operation is
   *                prepared
   * @runtime_ctrl: M2M runtime values for the control register.
   *
   * As EP93xx DMA controller doesn't support real chained DMA descriptors we
   * will have slightly different scheme here: @active points to a head of
   * flattened DMA descriptor chain.
   *
   * @queue holds pending transactions. These are linked through the first
   * descriptor in the chain. When a descriptor is moved to the @active queue,
   * the first and chained descriptors are flattened into a single list.
   *
   * @chan.private holds pointer to &struct ep93xx_dma_data which contains
   * necessary channel configuration information. For memcpy channels this must
   * be %NULL.
   */
  struct ep93xx_dma_chan {
  	struct dma_chan			chan;
  	const struct ep93xx_dma_engine	*edma;
  	void __iomem			*regs;
  	int				irq;
  	struct clk			*clk;
  	struct tasklet_struct		tasklet;
  	/* protects the fields following */
  	spinlock_t			lock;
  	unsigned long			flags;
  /* Channel is configured for cyclic transfers */
  #define EP93XX_DMA_IS_CYCLIC		0
  
  	int				buffer;
  	struct list_head		active;
  	struct list_head		queue;
  	struct list_head		free_list;
  	u32				runtime_addr;
  	u32				runtime_ctrl;
  };
  
  /**
   * struct ep93xx_dma_engine - the EP93xx DMA engine instance
   * @dma_dev: holds the dmaengine device
   * @m2m: is this an M2M or M2P device
   * @hw_setup: method which sets the channel up for operation
   * @hw_shutdown: shuts the channel down and flushes whatever is left
   * @hw_submit: pushes active descriptor(s) to the hardware
   * @hw_interrupt: handle the interrupt
   * @num_channels: number of channels for this instance
   * @channels: array of channels
   *
   * There is one instance of this struct for the M2P channels and one for the
   * M2M channels. hw_xxx() methods are used to perform operations which are
   * different on M2M and M2P channels. These methods are called with channel
   * lock held and interrupts disabled so they cannot sleep.
   */
  struct ep93xx_dma_engine {
  	struct dma_device	dma_dev;
  	bool			m2m;
  	int			(*hw_setup)(struct ep93xx_dma_chan *);
  	void			(*hw_shutdown)(struct ep93xx_dma_chan *);
  	void			(*hw_submit)(struct ep93xx_dma_chan *);
  	int			(*hw_interrupt)(struct ep93xx_dma_chan *);
  #define INTERRUPT_UNKNOWN	0
  #define INTERRUPT_DONE		1
  #define INTERRUPT_NEXT_BUFFER	2
  
  	size_t			num_channels;
  	struct ep93xx_dma_chan	channels[];
  };
  
  static inline struct device *chan2dev(struct ep93xx_dma_chan *edmac)
  {
  	return &edmac->chan.dev->device;
  }
  
  static struct ep93xx_dma_chan *to_ep93xx_dma_chan(struct dma_chan *chan)
  {
  	return container_of(chan, struct ep93xx_dma_chan, chan);
  }
  
  /**
   * ep93xx_dma_set_active - set new active descriptor chain
   * @edmac: channel
   * @desc: head of the new active descriptor chain
   *
   * Sets @desc to be the head of the new active descriptor chain. This is the
   * chain which is processed next. The active list must be empty before calling
   * this function.
   *
   * Called with @edmac->lock held and interrupts disabled.
   */
  static void ep93xx_dma_set_active(struct ep93xx_dma_chan *edmac,
  				  struct ep93xx_dma_desc *desc)
  {
  	BUG_ON(!list_empty(&edmac->active));
  
  	list_add_tail(&desc->node, &edmac->active);
  
  	/* Flatten the @desc->tx_list chain into @edmac->active list */
  	while (!list_empty(&desc->tx_list)) {
  		struct ep93xx_dma_desc *d = list_first_entry(&desc->tx_list,
  			struct ep93xx_dma_desc, node);
  
  		/*
  		 * We copy the callback parameters from the first descriptor
  		 * to all the chained descriptors. This way we can call the
  		 * callback without having to find out the first descriptor in
  		 * the chain. Useful for cyclic transfers.
  		 */
  		d->txd.callback = desc->txd.callback;
  		d->txd.callback_param = desc->txd.callback_param;
  
  		list_move_tail(&d->node, &edmac->active);
  	}
  }
  
  /* Called with @edmac->lock held and interrupts disabled */
  static struct ep93xx_dma_desc *
  ep93xx_dma_get_active(struct ep93xx_dma_chan *edmac)
  {
  	if (list_empty(&edmac->active))
  		return NULL;
  
  	return list_first_entry(&edmac->active, struct ep93xx_dma_desc, node);
  }
  
  /**
   * ep93xx_dma_advance_active - advances to the next active descriptor
   * @edmac: channel
   *
   * Function advances active descriptor to the next in the @edmac->active and
   * returns %true if we still have descriptors in the chain to process.
   * Otherwise returns %false.
   *
   * When the channel is in cyclic mode always returns %true.
   *
   * Called with @edmac->lock held and interrupts disabled.
   */
  static bool ep93xx_dma_advance_active(struct ep93xx_dma_chan *edmac)
  {
  	struct ep93xx_dma_desc *desc;
  
  	list_rotate_left(&edmac->active);
  
  	if (test_bit(EP93XX_DMA_IS_CYCLIC, &edmac->flags))
  		return true;
  
  	desc = ep93xx_dma_get_active(edmac);
  	if (!desc)
  		return false;
  
  	/*
  	 * If txd.cookie is set it means that we are back in the first
  	 * descriptor in the chain and hence done with it.
  	 */
  	return !desc->txd.cookie;
  }
  
  /*
   * M2P DMA implementation
   */
  
  static void m2p_set_control(struct ep93xx_dma_chan *edmac, u32 control)
  {
  	writel(control, edmac->regs + M2P_CONTROL);
  	/*
  	 * EP93xx User's Guide states that we must perform a dummy read after
  	 * write to the control register.
  	 */
  	readl(edmac->regs + M2P_CONTROL);
  }
  
  static int m2p_hw_setup(struct ep93xx_dma_chan *edmac)
  {
  	struct ep93xx_dma_data *data = edmac->chan.private;
  	u32 control;
  
  	writel(data->port & 0xf, edmac->regs + M2P_PPALLOC);
  
  	control = M2P_CONTROL_CH_ERROR_INT | M2P_CONTROL_ICE
  		| M2P_CONTROL_ENABLE;
  	m2p_set_control(edmac, control);
  
  	return 0;
  }
  
  static inline u32 m2p_channel_state(struct ep93xx_dma_chan *edmac)
  {
  	return (readl(edmac->regs + M2P_STATUS) >> 4) & 0x3;
  }
  
  static void m2p_hw_shutdown(struct ep93xx_dma_chan *edmac)
  {
  	u32 control;
  
  	control = readl(edmac->regs + M2P_CONTROL);
  	control &= ~(M2P_CONTROL_STALLINT | M2P_CONTROL_NFBINT);
  	m2p_set_control(edmac, control);
  
  	while (m2p_channel_state(edmac) >= M2P_STATE_ON)
  		cpu_relax();
  
  	m2p_set_control(edmac, 0);
  
  	while (m2p_channel_state(edmac) == M2P_STATE_STALL)
  		cpu_relax();
  }
  
  static void m2p_fill_desc(struct ep93xx_dma_chan *edmac)
  {
  	struct ep93xx_dma_desc *desc;
  	u32 bus_addr;
  
  	desc = ep93xx_dma_get_active(edmac);
  	if (!desc) {
  		dev_warn(chan2dev(edmac), "M2P: empty descriptor list
  ");
  		return;
  	}
  
  	if (ep93xx_dma_chan_direction(&edmac->chan) == DMA_MEM_TO_DEV)
  		bus_addr = desc->src_addr;
  	else
  		bus_addr = desc->dst_addr;
  
  	if (edmac->buffer == 0) {
  		writel(desc->size, edmac->regs + M2P_MAXCNT0);
  		writel(bus_addr, edmac->regs + M2P_BASE0);
  	} else {
  		writel(desc->size, edmac->regs + M2P_MAXCNT1);
  		writel(bus_addr, edmac->regs + M2P_BASE1);
  	}
  
  	edmac->buffer ^= 1;
  }
  
  static void m2p_hw_submit(struct ep93xx_dma_chan *edmac)
  {
  	u32 control = readl(edmac->regs + M2P_CONTROL);
  
  	m2p_fill_desc(edmac);
  	control |= M2P_CONTROL_STALLINT;
  
  	if (ep93xx_dma_advance_active(edmac)) {
  		m2p_fill_desc(edmac);
  		control |= M2P_CONTROL_NFBINT;
  	}
  
  	m2p_set_control(edmac, control);
  }
  
  static int m2p_hw_interrupt(struct ep93xx_dma_chan *edmac)
  {
  	u32 irq_status = readl(edmac->regs + M2P_INTERRUPT);
  	u32 control;
  
  	if (irq_status & M2P_INTERRUPT_ERROR) {
  		struct ep93xx_dma_desc *desc = ep93xx_dma_get_active(edmac);
  
  		/* Clear the error interrupt */
  		writel(1, edmac->regs + M2P_INTERRUPT);
  
  		/*
  		 * It seems that there is no easy way of reporting errors back
  		 * to client so we just report the error here and continue as
  		 * usual.
  		 *
  		 * Revisit this when there is a mechanism to report back the
  		 * errors.
  		 */
  		dev_err(chan2dev(edmac),
  			"DMA transfer failed! Details:
  "
  			"\tcookie	: %d
  "
  			"\tsrc_addr	: 0x%08x
  "
  			"\tdst_addr	: 0x%08x
  "
  			"\tsize		: %zu
  ",
  			desc->txd.cookie, desc->src_addr, desc->dst_addr,
  			desc->size);
  	}
  
  	switch (irq_status & (M2P_INTERRUPT_STALL | M2P_INTERRUPT_NFB)) {
  	case M2P_INTERRUPT_STALL:
  		/* Disable interrupts */
  		control = readl(edmac->regs + M2P_CONTROL);
  		control &= ~(M2P_CONTROL_STALLINT | M2P_CONTROL_NFBINT);
  		m2p_set_control(edmac, control);
  
  		return INTERRUPT_DONE;
  
  	case M2P_INTERRUPT_NFB:
  		if (ep93xx_dma_advance_active(edmac))
  			m2p_fill_desc(edmac);
  
  		return INTERRUPT_NEXT_BUFFER;
  	}
  
  	return INTERRUPT_UNKNOWN;
  }
  
  /*
   * M2M DMA implementation
   */
  
  static int m2m_hw_setup(struct ep93xx_dma_chan *edmac)
  {
  	const struct ep93xx_dma_data *data = edmac->chan.private;
  	u32 control = 0;
  
  	if (!data) {
  		/* This is memcpy channel, nothing to configure */
  		writel(control, edmac->regs + M2M_CONTROL);
  		return 0;
  	}
  
  	switch (data->port) {
  	case EP93XX_DMA_SSP:
  		/*
  		 * This was found via experimenting - anything less than 5
  		 * causes the channel to perform only a partial transfer which
  		 * leads to problems since we don't get DONE interrupt then.
  		 */
  		control = (5 << M2M_CONTROL_PWSC_SHIFT);
  		control |= M2M_CONTROL_NO_HDSK;
  
  		if (data->direction == DMA_MEM_TO_DEV) {
  			control |= M2M_CONTROL_DAH;
  			control |= M2M_CONTROL_TM_TX;
  			control |= M2M_CONTROL_RSS_SSPTX;
  		} else {
  			control |= M2M_CONTROL_SAH;
  			control |= M2M_CONTROL_TM_RX;
  			control |= M2M_CONTROL_RSS_SSPRX;
  		}
  		break;
  
  	case EP93XX_DMA_IDE:
  		/*
  		 * This IDE part is totally untested. Values below are taken
  		 * from the EP93xx Users's Guide and might not be correct.
  		 */
  		if (data->direction == DMA_MEM_TO_DEV) {
  			/* Worst case from the UG */
  			control = (3 << M2M_CONTROL_PWSC_SHIFT);
  			control |= M2M_CONTROL_DAH;
  			control |= M2M_CONTROL_TM_TX;
  		} else {
  			control = (2 << M2M_CONTROL_PWSC_SHIFT);
  			control |= M2M_CONTROL_SAH;
  			control |= M2M_CONTROL_TM_RX;
  		}
  
  		control |= M2M_CONTROL_NO_HDSK;
  		control |= M2M_CONTROL_RSS_IDE;
  		control |= M2M_CONTROL_PW_16;
  		break;
  
  	default:
  		return -EINVAL;
  	}
  
  	writel(control, edmac->regs + M2M_CONTROL);
  	return 0;
  }
  
  static void m2m_hw_shutdown(struct ep93xx_dma_chan *edmac)
  {
  	/* Just disable the channel */
  	writel(0, edmac->regs + M2M_CONTROL);
  }
  
  static void m2m_fill_desc(struct ep93xx_dma_chan *edmac)
  {
  	struct ep93xx_dma_desc *desc;
  
  	desc = ep93xx_dma_get_active(edmac);
  	if (!desc) {
  		dev_warn(chan2dev(edmac), "M2M: empty descriptor list
  ");
  		return;
  	}
  
  	if (edmac->buffer == 0) {
  		writel(desc->src_addr, edmac->regs + M2M_SAR_BASE0);
  		writel(desc->dst_addr, edmac->regs + M2M_DAR_BASE0);
  		writel(desc->size, edmac->regs + M2M_BCR0);
  	} else {
  		writel(desc->src_addr, edmac->regs + M2M_SAR_BASE1);
  		writel(desc->dst_addr, edmac->regs + M2M_DAR_BASE1);
  		writel(desc->size, edmac->regs + M2M_BCR1);
  	}
  
  	edmac->buffer ^= 1;
  }
  
  static void m2m_hw_submit(struct ep93xx_dma_chan *edmac)
  {
  	struct ep93xx_dma_data *data = edmac->chan.private;
  	u32 control = readl(edmac->regs + M2M_CONTROL);
  
  	/*
  	 * Since we allow clients to configure PW (peripheral width) we always
  	 * clear PW bits here and then set them according what is given in
  	 * the runtime configuration.
  	 */
  	control &= ~M2M_CONTROL_PW_MASK;
  	control |= edmac->runtime_ctrl;
  
  	m2m_fill_desc(edmac);
  	control |= M2M_CONTROL_DONEINT;
  
  	if (ep93xx_dma_advance_active(edmac)) {
  		m2m_fill_desc(edmac);
  		control |= M2M_CONTROL_NFBINT;
  	}
  
  	/*
  	 * Now we can finally enable the channel. For M2M channel this must be
  	 * done _after_ the BCRx registers are programmed.
  	 */
  	control |= M2M_CONTROL_ENABLE;
  	writel(control, edmac->regs + M2M_CONTROL);
  
  	if (!data) {
  		/*
  		 * For memcpy channels the software trigger must be asserted
  		 * in order to start the memcpy operation.
  		 */
  		control |= M2M_CONTROL_START;
  		writel(control, edmac->regs + M2M_CONTROL);
  	}
  }
  
  /*
   * According to EP93xx User's Guide, we should receive DONE interrupt when all
   * M2M DMA controller transactions complete normally. This is not always the
   * case - sometimes EP93xx M2M DMA asserts DONE interrupt when the DMA channel
   * is still running (channel Buffer FSM in DMA_BUF_ON state, and channel
   * Control FSM in DMA_MEM_RD state, observed at least in IDE-DMA operation).
   * In effect, disabling the channel when only DONE bit is set could stop
   * currently running DMA transfer. To avoid this, we use Buffer FSM and
   * Control FSM to check current state of DMA channel.
   */
  static int m2m_hw_interrupt(struct ep93xx_dma_chan *edmac)
  {
  	u32 status = readl(edmac->regs + M2M_STATUS);
  	u32 ctl_fsm = status & M2M_STATUS_CTL_MASK;
  	u32 buf_fsm = status & M2M_STATUS_BUF_MASK;
  	bool done = status & M2M_STATUS_DONE;
  	bool last_done;
  	u32 control;
  	struct ep93xx_dma_desc *desc;
  
  	/* Accept only DONE and NFB interrupts */
  	if (!(readl(edmac->regs + M2M_INTERRUPT) & M2M_INTERRUPT_MASK))
  		return INTERRUPT_UNKNOWN;
  
  	if (done) {
  		/* Clear the DONE bit */
  		writel(0, edmac->regs + M2M_INTERRUPT);
  	}
  
  	/*
  	 * Check whether we are done with descriptors or not. This, together
  	 * with DMA channel state, determines action to take in interrupt.
  	 */
  	desc = ep93xx_dma_get_active(edmac);
  	last_done = !desc || desc->txd.cookie;
  
  	/*
  	 * Use M2M DMA Buffer FSM and Control FSM to check current state of
  	 * DMA channel. Using DONE and NFB bits from channel status register
  	 * or bits from channel interrupt register is not reliable.
  	 */
  	if (!last_done &&
  	    (buf_fsm == M2M_STATUS_BUF_NO ||
  	     buf_fsm == M2M_STATUS_BUF_ON)) {
  		/*
  		 * Two buffers are ready for update when Buffer FSM is in
  		 * DMA_NO_BUF state. Only one buffer can be prepared without
  		 * disabling the channel or polling the DONE bit.
  		 * To simplify things, always prepare only one buffer.
  		 */
  		if (ep93xx_dma_advance_active(edmac)) {
  			m2m_fill_desc(edmac);
  			if (done && !edmac->chan.private) {
  				/* Software trigger for memcpy channel */
  				control = readl(edmac->regs + M2M_CONTROL);
  				control |= M2M_CONTROL_START;
  				writel(control, edmac->regs + M2M_CONTROL);
  			}
  			return INTERRUPT_NEXT_BUFFER;
  		} else {
  			last_done = true;
  		}
  	}
  
  	/*
  	 * Disable the channel only when Buffer FSM is in DMA_NO_BUF state
  	 * and Control FSM is in DMA_STALL state.
  	 */
  	if (last_done &&
  	    buf_fsm == M2M_STATUS_BUF_NO &&
  	    ctl_fsm == M2M_STATUS_CTL_STALL) {
  		/* Disable interrupts and the channel */
  		control = readl(edmac->regs + M2M_CONTROL);
  		control &= ~(M2M_CONTROL_DONEINT | M2M_CONTROL_NFBINT
  			    | M2M_CONTROL_ENABLE);
  		writel(control, edmac->regs + M2M_CONTROL);
  		return INTERRUPT_DONE;
  	}
  
  	/*
  	 * Nothing to do this time.
  	 */
  	return INTERRUPT_NEXT_BUFFER;
  }
  
  /*
   * DMA engine API implementation
   */
  
  static struct ep93xx_dma_desc *
  ep93xx_dma_desc_get(struct ep93xx_dma_chan *edmac)
  {
  	struct ep93xx_dma_desc *desc, *_desc;
  	struct ep93xx_dma_desc *ret = NULL;
  	unsigned long flags;
  
  	spin_lock_irqsave(&edmac->lock, flags);
  	list_for_each_entry_safe(desc, _desc, &edmac->free_list, node) {
  		if (async_tx_test_ack(&desc->txd)) {
  			list_del_init(&desc->node);
  
  			/* Re-initialize the descriptor */
  			desc->src_addr = 0;
  			desc->dst_addr = 0;
  			desc->size = 0;
  			desc->complete = false;
  			desc->txd.cookie = 0;
  			desc->txd.callback = NULL;
  			desc->txd.callback_param = NULL;
  
  			ret = desc;
  			break;
  		}
  	}
  	spin_unlock_irqrestore(&edmac->lock, flags);
  	return ret;
  }
  
  static void ep93xx_dma_desc_put(struct ep93xx_dma_chan *edmac,
  				struct ep93xx_dma_desc *desc)
  {
  	if (desc) {
  		unsigned long flags;
  
  		spin_lock_irqsave(&edmac->lock, flags);
  		list_splice_init(&desc->tx_list, &edmac->free_list);
  		list_add(&desc->node, &edmac->free_list);
  		spin_unlock_irqrestore(&edmac->lock, flags);
  	}
  }
  
  /**
   * ep93xx_dma_advance_work - start processing the next pending transaction
   * @edmac: channel
   *
   * If we have pending transactions queued and we are currently idling, this
   * function takes the next queued transaction from the @edmac->queue and
   * pushes it to the hardware for execution.
   */
  static void ep93xx_dma_advance_work(struct ep93xx_dma_chan *edmac)
  {
  	struct ep93xx_dma_desc *new;
  	unsigned long flags;
  
  	spin_lock_irqsave(&edmac->lock, flags);
  	if (!list_empty(&edmac->active) || list_empty(&edmac->queue)) {
  		spin_unlock_irqrestore(&edmac->lock, flags);
  		return;
  	}
  
  	/* Take the next descriptor from the pending queue */
  	new = list_first_entry(&edmac->queue, struct ep93xx_dma_desc, node);
  	list_del_init(&new->node);
  
  	ep93xx_dma_set_active(edmac, new);
  
  	/* Push it to the hardware */
  	edmac->edma->hw_submit(edmac);
  	spin_unlock_irqrestore(&edmac->lock, flags);
  }
  
  static void ep93xx_dma_tasklet(unsigned long data)
  {
  	struct ep93xx_dma_chan *edmac = (struct ep93xx_dma_chan *)data;
  	struct ep93xx_dma_desc *desc, *d;
  	dma_async_tx_callback callback = NULL;
  	void *callback_param = NULL;
  	LIST_HEAD(list);
  
  	spin_lock_irq(&edmac->lock);
  	/*
  	 * If dma_terminate_all() was called before we get to run, the active
  	 * list has become empty. If that happens we aren't supposed to do
  	 * anything more than call ep93xx_dma_advance_work().
  	 */
  	desc = ep93xx_dma_get_active(edmac);
  	if (desc) {
  		if (desc->complete) {
  			/* mark descriptor complete for non cyclic case only */
  			if (!test_bit(EP93XX_DMA_IS_CYCLIC, &edmac->flags))
  				dma_cookie_complete(&desc->txd);
  			list_splice_init(&edmac->active, &list);
  		}
  		callback = desc->txd.callback;
  		callback_param = desc->txd.callback_param;
  	}
  	spin_unlock_irq(&edmac->lock);
  
  	/* Pick up the next descriptor from the queue */
  	ep93xx_dma_advance_work(edmac);
  
  	/* Now we can release all the chained descriptors */
  	list_for_each_entry_safe(desc, d, &list, node) {
  		dma_descriptor_unmap(&desc->txd);
  		ep93xx_dma_desc_put(edmac, desc);
  	}
  
  	if (callback)
  		callback(callback_param);
  }
  
  static irqreturn_t ep93xx_dma_interrupt(int irq, void *dev_id)
  {
  	struct ep93xx_dma_chan *edmac = dev_id;
  	struct ep93xx_dma_desc *desc;
  	irqreturn_t ret = IRQ_HANDLED;
  
  	spin_lock(&edmac->lock);
  
  	desc = ep93xx_dma_get_active(edmac);
  	if (!desc) {
  		dev_warn(chan2dev(edmac),
  			 "got interrupt while active list is empty
  ");
  		spin_unlock(&edmac->lock);
  		return IRQ_NONE;
  	}
  
  	switch (edmac->edma->hw_interrupt(edmac)) {
  	case INTERRUPT_DONE:
  		desc->complete = true;
  		tasklet_schedule(&edmac->tasklet);
  		break;
  
  	case INTERRUPT_NEXT_BUFFER:
  		if (test_bit(EP93XX_DMA_IS_CYCLIC, &edmac->flags))
  			tasklet_schedule(&edmac->tasklet);
  		break;
  
  	default:
  		dev_warn(chan2dev(edmac), "unknown interrupt!
  ");
  		ret = IRQ_NONE;
  		break;
  	}
  
  	spin_unlock(&edmac->lock);
  	return ret;
  }
  
  /**
   * ep93xx_dma_tx_submit - set the prepared descriptor(s) to be executed
   * @tx: descriptor to be executed
   *
   * Function will execute given descriptor on the hardware or if the hardware
   * is busy, queue the descriptor to be executed later on. Returns cookie which
   * can be used to poll the status of the descriptor.
   */
  static dma_cookie_t ep93xx_dma_tx_submit(struct dma_async_tx_descriptor *tx)
  {
  	struct ep93xx_dma_chan *edmac = to_ep93xx_dma_chan(tx->chan);
  	struct ep93xx_dma_desc *desc;
  	dma_cookie_t cookie;
  	unsigned long flags;
  
  	spin_lock_irqsave(&edmac->lock, flags);
  	cookie = dma_cookie_assign(tx);
  
  	desc = container_of(tx, struct ep93xx_dma_desc, txd);
  
  	/*
  	 * If nothing is currently prosessed, we push this descriptor
  	 * directly to the hardware. Otherwise we put the descriptor
  	 * to the pending queue.
  	 */
  	if (list_empty(&edmac->active)) {
  		ep93xx_dma_set_active(edmac, desc);
  		edmac->edma->hw_submit(edmac);
  	} else {
  		list_add_tail(&desc->node, &edmac->queue);
  	}
  
  	spin_unlock_irqrestore(&edmac->lock, flags);
  	return cookie;
  }
  
  /**
   * ep93xx_dma_alloc_chan_resources - allocate resources for the channel
   * @chan: channel to allocate resources
   *
   * Function allocates necessary resources for the given DMA channel and
   * returns number of allocated descriptors for the channel. Negative errno
   * is returned in case of failure.
   */
  static int ep93xx_dma_alloc_chan_resources(struct dma_chan *chan)
  {
  	struct ep93xx_dma_chan *edmac = to_ep93xx_dma_chan(chan);
  	struct ep93xx_dma_data *data = chan->private;
  	const char *name = dma_chan_name(chan);
  	int ret, i;
  
  	/* Sanity check the channel parameters */
  	if (!edmac->edma->m2m) {
  		if (!data)
  			return -EINVAL;
  		if (data->port < EP93XX_DMA_I2S1 ||
  		    data->port > EP93XX_DMA_IRDA)
  			return -EINVAL;
  		if (data->direction != ep93xx_dma_chan_direction(chan))
  			return -EINVAL;
  	} else {
  		if (data) {
  			switch (data->port) {
  			case EP93XX_DMA_SSP:
  			case EP93XX_DMA_IDE:
  				if (!is_slave_direction(data->direction))
  					return -EINVAL;
  				break;
  			default:
  				return -EINVAL;
  			}
  		}
  	}
  
  	if (data && data->name)
  		name = data->name;
  
  	ret = clk_enable(edmac->clk);
  	if (ret)
  		return ret;
  
  	ret = request_irq(edmac->irq, ep93xx_dma_interrupt, 0, name, edmac);
  	if (ret)
  		goto fail_clk_disable;
  
  	spin_lock_irq(&edmac->lock);
  	dma_cookie_init(&edmac->chan);
  	ret = edmac->edma->hw_setup(edmac);
  	spin_unlock_irq(&edmac->lock);
  
  	if (ret)
  		goto fail_free_irq;
  
  	for (i = 0; i < DMA_MAX_CHAN_DESCRIPTORS; i++) {
  		struct ep93xx_dma_desc *desc;
  
  		desc = kzalloc(sizeof(*desc), GFP_KERNEL);
  		if (!desc) {
  			dev_warn(chan2dev(edmac), "not enough descriptors
  ");
  			break;
  		}
  
  		INIT_LIST_HEAD(&desc->tx_list);
  
  		dma_async_tx_descriptor_init(&desc->txd, chan);
  		desc->txd.flags = DMA_CTRL_ACK;
  		desc->txd.tx_submit = ep93xx_dma_tx_submit;
  
  		ep93xx_dma_desc_put(edmac, desc);
  	}
  
  	return i;
  
  fail_free_irq:
  	free_irq(edmac->irq, edmac);
  fail_clk_disable:
  	clk_disable(edmac->clk);
  
  	return ret;
  }
  
  /**
   * ep93xx_dma_free_chan_resources - release resources for the channel
   * @chan: channel
   *
   * Function releases all the resources allocated for the given channel.
   * The channel must be idle when this is called.
   */
  static void ep93xx_dma_free_chan_resources(struct dma_chan *chan)
  {
  	struct ep93xx_dma_chan *edmac = to_ep93xx_dma_chan(chan);
  	struct ep93xx_dma_desc *desc, *d;
  	unsigned long flags;
  	LIST_HEAD(list);
  
  	BUG_ON(!list_empty(&edmac->active));
  	BUG_ON(!list_empty(&edmac->queue));
  
  	spin_lock_irqsave(&edmac->lock, flags);
  	edmac->edma->hw_shutdown(edmac);
  	edmac->runtime_addr = 0;
  	edmac->runtime_ctrl = 0;
  	edmac->buffer = 0;
  	list_splice_init(&edmac->free_list, &list);
  	spin_unlock_irqrestore(&edmac->lock, flags);
  
  	list_for_each_entry_safe(desc, d, &list, node)
  		kfree(desc);
  
  	clk_disable(edmac->clk);
  	free_irq(edmac->irq, edmac);
  }
  
  /**
   * ep93xx_dma_prep_dma_memcpy - prepare a memcpy DMA operation
   * @chan: channel
   * @dest: destination bus address
   * @src: source bus address
   * @len: size of the transaction
   * @flags: flags for the descriptor
   *
   * Returns a valid DMA descriptor or %NULL in case of failure.
   */
  static struct dma_async_tx_descriptor *
  ep93xx_dma_prep_dma_memcpy(struct dma_chan *chan, dma_addr_t dest,
  			   dma_addr_t src, size_t len, unsigned long flags)
  {
  	struct ep93xx_dma_chan *edmac = to_ep93xx_dma_chan(chan);
  	struct ep93xx_dma_desc *desc, *first;
  	size_t bytes, offset;
  
  	first = NULL;
  	for (offset = 0; offset < len; offset += bytes) {
  		desc = ep93xx_dma_desc_get(edmac);
  		if (!desc) {
  			dev_warn(chan2dev(edmac), "couln't get descriptor
  ");
  			goto fail;
  		}
  
  		bytes = min_t(size_t, len - offset, DMA_MAX_CHAN_BYTES);
  
  		desc->src_addr = src + offset;
  		desc->dst_addr = dest + offset;
  		desc->size = bytes;
  
  		if (!first)
  			first = desc;
  		else
  			list_add_tail(&desc->node, &first->tx_list);
  	}
  
  	first->txd.cookie = -EBUSY;
  	first->txd.flags = flags;
  
  	return &first->txd;
  fail:
  	ep93xx_dma_desc_put(edmac, first);
  	return NULL;
  }
  
  /**
   * ep93xx_dma_prep_slave_sg - prepare a slave DMA operation
   * @chan: channel
   * @sgl: list of buffers to transfer
   * @sg_len: number of entries in @sgl
   * @dir: direction of tha DMA transfer
   * @flags: flags for the descriptor
   * @context: operation context (ignored)
   *
   * Returns a valid DMA descriptor or %NULL in case of failure.
   */
  static struct dma_async_tx_descriptor *
  ep93xx_dma_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
  			 unsigned int sg_len, enum dma_transfer_direction dir,
  			 unsigned long flags, void *context)
  {
  	struct ep93xx_dma_chan *edmac = to_ep93xx_dma_chan(chan);
  	struct ep93xx_dma_desc *desc, *first;
  	struct scatterlist *sg;
  	int i;
  
  	if (!edmac->edma->m2m && dir != ep93xx_dma_chan_direction(chan)) {
  		dev_warn(chan2dev(edmac),
  			 "channel was configured with different direction
  ");
  		return NULL;
  	}
  
  	if (test_bit(EP93XX_DMA_IS_CYCLIC, &edmac->flags)) {
  		dev_warn(chan2dev(edmac),
  			 "channel is already used for cyclic transfers
  ");
  		return NULL;
  	}
  
  	first = NULL;
  	for_each_sg(sgl, sg, sg_len, i) {
  		size_t sg_len = sg_dma_len(sg);
  
  		if (sg_len > DMA_MAX_CHAN_BYTES) {
  			dev_warn(chan2dev(edmac), "too big transfer size %d
  ",
  				 sg_len);
  			goto fail;
  		}
  
  		desc = ep93xx_dma_desc_get(edmac);
  		if (!desc) {
  			dev_warn(chan2dev(edmac), "couln't get descriptor
  ");
  			goto fail;
  		}
  
  		if (dir == DMA_MEM_TO_DEV) {
  			desc->src_addr = sg_dma_address(sg);
  			desc->dst_addr = edmac->runtime_addr;
  		} else {
  			desc->src_addr = edmac->runtime_addr;
  			desc->dst_addr = sg_dma_address(sg);
  		}
  		desc->size = sg_len;
  
  		if (!first)
  			first = desc;
  		else
  			list_add_tail(&desc->node, &first->tx_list);
  	}
  
  	first->txd.cookie = -EBUSY;
  	first->txd.flags = flags;
  
  	return &first->txd;
  
  fail:
  	ep93xx_dma_desc_put(edmac, first);
  	return NULL;
  }
  
  /**
   * ep93xx_dma_prep_dma_cyclic - prepare a cyclic DMA operation
   * @chan: channel
   * @dma_addr: DMA mapped address of the buffer
   * @buf_len: length of the buffer (in bytes)
   * @period_len: length of a single period
   * @dir: direction of the operation
   * @flags: tx descriptor status flags
   * @context: operation context (ignored)
   *
   * Prepares a descriptor for cyclic DMA operation. This means that once the
   * descriptor is submitted, we will be submitting in a @period_len sized
   * buffers and calling callback once the period has been elapsed. Transfer
   * terminates only when client calls dmaengine_terminate_all() for this
   * channel.
   *
   * Returns a valid DMA descriptor or %NULL in case of failure.
   */
  static struct dma_async_tx_descriptor *
  ep93xx_dma_prep_dma_cyclic(struct dma_chan *chan, dma_addr_t dma_addr,
  			   size_t buf_len, size_t period_len,
  			   enum dma_transfer_direction dir, unsigned long flags,
  			   void *context)
  {
  	struct ep93xx_dma_chan *edmac = to_ep93xx_dma_chan(chan);
  	struct ep93xx_dma_desc *desc, *first;
  	size_t offset = 0;
  
  	if (!edmac->edma->m2m && dir != ep93xx_dma_chan_direction(chan)) {
  		dev_warn(chan2dev(edmac),
  			 "channel was configured with different direction
  ");
  		return NULL;
  	}
  
  	if (test_and_set_bit(EP93XX_DMA_IS_CYCLIC, &edmac->flags)) {
  		dev_warn(chan2dev(edmac),
  			 "channel is already used for cyclic transfers
  ");
  		return NULL;
  	}
  
  	if (period_len > DMA_MAX_CHAN_BYTES) {
  		dev_warn(chan2dev(edmac), "too big period length %d
  ",
  			 period_len);
  		return NULL;
  	}
  
  	/* Split the buffer into period size chunks */
  	first = NULL;
  	for (offset = 0; offset < buf_len; offset += period_len) {
  		desc = ep93xx_dma_desc_get(edmac);
  		if (!desc) {
  			dev_warn(chan2dev(edmac), "couln't get descriptor
  ");
  			goto fail;
  		}
  
  		if (dir == DMA_MEM_TO_DEV) {
  			desc->src_addr = dma_addr + offset;
  			desc->dst_addr = edmac->runtime_addr;
  		} else {
  			desc->src_addr = edmac->runtime_addr;
  			desc->dst_addr = dma_addr + offset;
  		}
  
  		desc->size = period_len;
  
  		if (!first)
  			first = desc;
  		else
  			list_add_tail(&desc->node, &first->tx_list);
  	}
  
  	first->txd.cookie = -EBUSY;
  
  	return &first->txd;
  
  fail:
  	ep93xx_dma_desc_put(edmac, first);
  	return NULL;
  }
  
  /**
   * ep93xx_dma_terminate_all - terminate all transactions
   * @edmac: channel
   *
   * Stops all DMA transactions. All descriptors are put back to the
   * @edmac->free_list and callbacks are _not_ called.
   */
  static int ep93xx_dma_terminate_all(struct ep93xx_dma_chan *edmac)
  {
  	struct ep93xx_dma_desc *desc, *_d;
  	unsigned long flags;
  	LIST_HEAD(list);
  
  	spin_lock_irqsave(&edmac->lock, flags);
  	/* First we disable and flush the DMA channel */
  	edmac->edma->hw_shutdown(edmac);
  	clear_bit(EP93XX_DMA_IS_CYCLIC, &edmac->flags);
  	list_splice_init(&edmac->active, &list);
  	list_splice_init(&edmac->queue, &list);
  	/*
  	 * We then re-enable the channel. This way we can continue submitting
  	 * the descriptors by just calling ->hw_submit() again.
  	 */
  	edmac->edma->hw_setup(edmac);
  	spin_unlock_irqrestore(&edmac->lock, flags);
  
  	list_for_each_entry_safe(desc, _d, &list, node)
  		ep93xx_dma_desc_put(edmac, desc);
  
  	return 0;
  }
  
  static int ep93xx_dma_slave_config(struct ep93xx_dma_chan *edmac,
  				   struct dma_slave_config *config)
  {
  	enum dma_slave_buswidth width;
  	unsigned long flags;
  	u32 addr, ctrl;
  
  	if (!edmac->edma->m2m)
  		return -EINVAL;
  
  	switch (config->direction) {
  	case DMA_DEV_TO_MEM:
  		width = config->src_addr_width;
  		addr = config->src_addr;
  		break;
  
  	case DMA_MEM_TO_DEV:
  		width = config->dst_addr_width;
  		addr = config->dst_addr;
  		break;
  
  	default:
  		return -EINVAL;
  	}
  
  	switch (width) {
  	case DMA_SLAVE_BUSWIDTH_1_BYTE:
  		ctrl = 0;
  		break;
  	case DMA_SLAVE_BUSWIDTH_2_BYTES:
  		ctrl = M2M_CONTROL_PW_16;
  		break;
  	case DMA_SLAVE_BUSWIDTH_4_BYTES:
  		ctrl = M2M_CONTROL_PW_32;
  		break;
  	default:
  		return -EINVAL;
  	}
  
  	spin_lock_irqsave(&edmac->lock, flags);
  	edmac->runtime_addr = addr;
  	edmac->runtime_ctrl = ctrl;
  	spin_unlock_irqrestore(&edmac->lock, flags);
  
  	return 0;
  }
  
  /**
   * ep93xx_dma_control - manipulate all pending operations on a channel
   * @chan: channel
   * @cmd: control command to perform
   * @arg: optional argument
   *
   * Controls the channel. Function returns %0 in case of success or negative
   * error in case of failure.
   */
  static int ep93xx_dma_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
  			      unsigned long arg)
  {
  	struct ep93xx_dma_chan *edmac = to_ep93xx_dma_chan(chan);
  	struct dma_slave_config *config;
  
  	switch (cmd) {
  	case DMA_TERMINATE_ALL:
  		return ep93xx_dma_terminate_all(edmac);
  
  	case DMA_SLAVE_CONFIG:
  		config = (struct dma_slave_config *)arg;
  		return ep93xx_dma_slave_config(edmac, config);
  
  	default:
  		break;
  	}
  
  	return -ENOSYS;
  }
  
  /**
   * ep93xx_dma_tx_status - check if a transaction is completed
   * @chan: channel
   * @cookie: transaction specific cookie
   * @state: state of the transaction is stored here if given
   *
   * This function can be used to query state of a given transaction.
   */
  static enum dma_status ep93xx_dma_tx_status(struct dma_chan *chan,
  					    dma_cookie_t cookie,
  					    struct dma_tx_state *state)
  {
  	return dma_cookie_status(chan, cookie, state);
  }
  
  /**
   * ep93xx_dma_issue_pending - push pending transactions to the hardware
   * @chan: channel
   *
   * When this function is called, all pending transactions are pushed to the
   * hardware and executed.
   */
  static void ep93xx_dma_issue_pending(struct dma_chan *chan)
  {
  	ep93xx_dma_advance_work(to_ep93xx_dma_chan(chan));
  }
  
  static int __init ep93xx_dma_probe(struct platform_device *pdev)
  {
  	struct ep93xx_dma_platform_data *pdata = dev_get_platdata(&pdev->dev);
  	struct ep93xx_dma_engine *edma;
  	struct dma_device *dma_dev;
  	size_t edma_size;
  	int ret, i;
  
  	edma_size = pdata->num_channels * sizeof(struct ep93xx_dma_chan);
  	edma = kzalloc(sizeof(*edma) + edma_size, GFP_KERNEL);
  	if (!edma)
  		return -ENOMEM;
  
  	dma_dev = &edma->dma_dev;
  	edma->m2m = platform_get_device_id(pdev)->driver_data;
  	edma->num_channels = pdata->num_channels;
  
  	INIT_LIST_HEAD(&dma_dev->channels);
  	for (i = 0; i < pdata->num_channels; i++) {
  		const struct ep93xx_dma_chan_data *cdata = &pdata->channels[i];
  		struct ep93xx_dma_chan *edmac = &edma->channels[i];
  
  		edmac->chan.device = dma_dev;
  		edmac->regs = cdata->base;
  		edmac->irq = cdata->irq;
  		edmac->edma = edma;
  
  		edmac->clk = clk_get(NULL, cdata->name);
  		if (IS_ERR(edmac->clk)) {
  			dev_warn(&pdev->dev, "failed to get clock for %s
  ",
  				 cdata->name);
  			continue;
  		}
  
  		spin_lock_init(&edmac->lock);
  		INIT_LIST_HEAD(&edmac->active);
  		INIT_LIST_HEAD(&edmac->queue);
  		INIT_LIST_HEAD(&edmac->free_list);
  		tasklet_init(&edmac->tasklet, ep93xx_dma_tasklet,
  			     (unsigned long)edmac);
  
  		list_add_tail(&edmac->chan.device_node,
  			      &dma_dev->channels);
  	}
  
  	dma_cap_zero(dma_dev->cap_mask);
  	dma_cap_set(DMA_SLAVE, dma_dev->cap_mask);
  	dma_cap_set(DMA_CYCLIC, dma_dev->cap_mask);
  
  	dma_dev->dev = &pdev->dev;
  	dma_dev->device_alloc_chan_resources = ep93xx_dma_alloc_chan_resources;
  	dma_dev->device_free_chan_resources = ep93xx_dma_free_chan_resources;
  	dma_dev->device_prep_slave_sg = ep93xx_dma_prep_slave_sg;
  	dma_dev->device_prep_dma_cyclic = ep93xx_dma_prep_dma_cyclic;
  	dma_dev->device_control = ep93xx_dma_control;
  	dma_dev->device_issue_pending = ep93xx_dma_issue_pending;
  	dma_dev->device_tx_status = ep93xx_dma_tx_status;
  
  	dma_set_max_seg_size(dma_dev->dev, DMA_MAX_CHAN_BYTES);
  
  	if (edma->m2m) {
  		dma_cap_set(DMA_MEMCPY, dma_dev->cap_mask);
  		dma_dev->device_prep_dma_memcpy = ep93xx_dma_prep_dma_memcpy;
  
  		edma->hw_setup = m2m_hw_setup;
  		edma->hw_shutdown = m2m_hw_shutdown;
  		edma->hw_submit = m2m_hw_submit;
  		edma->hw_interrupt = m2m_hw_interrupt;
  	} else {
  		dma_cap_set(DMA_PRIVATE, dma_dev->cap_mask);
  
  		edma->hw_setup = m2p_hw_setup;
  		edma->hw_shutdown = m2p_hw_shutdown;
  		edma->hw_submit = m2p_hw_submit;
  		edma->hw_interrupt = m2p_hw_interrupt;
  	}
  
  	ret = dma_async_device_register(dma_dev);
  	if (unlikely(ret)) {
  		for (i = 0; i < edma->num_channels; i++) {
  			struct ep93xx_dma_chan *edmac = &edma->channels[i];
  			if (!IS_ERR_OR_NULL(edmac->clk))
  				clk_put(edmac->clk);
  		}
  		kfree(edma);
  	} else {
  		dev_info(dma_dev->dev, "EP93xx M2%s DMA ready
  ",
  			 edma->m2m ? "M" : "P");
  	}
  
  	return ret;
  }
  
  static struct platform_device_id ep93xx_dma_driver_ids[] = {
  	{ "ep93xx-dma-m2p", 0 },
  	{ "ep93xx-dma-m2m", 1 },
  	{ },
  };
  
  static struct platform_driver ep93xx_dma_driver = {
  	.driver		= {
  		.name	= "ep93xx-dma",
  	},
  	.id_table	= ep93xx_dma_driver_ids,
  };
  
  static int __init ep93xx_dma_module_init(void)
  {
  	return platform_driver_probe(&ep93xx_dma_driver, ep93xx_dma_probe);
  }
  subsys_initcall(ep93xx_dma_module_init);
  
  MODULE_AUTHOR("Mika Westerberg <mika.westerberg@iki.fi>");
  MODULE_DESCRIPTION("EP93xx DMA driver");
  MODULE_LICENSE("GPL");